chapter 17. supraglottic airway devices

8/11/2019 Chapter 17. Supraglottic Airway Devices

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Chapter 17

Supraglottic Airway DevicesP.462

Supraglott ic ai rway devices have become a standard f ixture in airway management,

f i l l ing a niche between the face mask and tracheal tube in terms of both anatomical

position and degree of invasiveness. These devices sit outside the trachea but

provide a handsfree means of achieving a gas-tight airway.

The f irst s uccessful supraglottic airway d evice, the Laryngeal Mask Airway (LMA)-

Classic, became available in 1989. As t ime went on, a ddit ional devices were added

to the LMA family to sat isfy specif ic needs, and a number of other devices were

developed (1,2). There are a large number of supraglott ic airway devices, some of

which appear similar to the LMA family and others that work under a different

concept. I t is not possible to discuss all of these devices, because they are being

introduced at a rapid rate while others are disappearing. Those that seem to be

gaining acceptance and longevity at the t ime this writ ing wil l be discussed.

Laryngeal Mask Airway Family

T y p e s

LMA-Classic

De s c r i p t i o n

The LMA-Classic (standard LMA, Classic LMA, LMA-C, cLMA) consists of a curved

tube (shaft) connected to an ell ipt ical spoon-shaped mask (cup) at a 30 angle (Fig.

17.1). There are two flexible vertical bars where the tube enters the mask to

prevent the tube from being obstructed by the epiglott is. An inf latable cuff

surrounds the inner r im of the mask. An inf lat ion tube and self-sealing pilot balloonare attached to the proximal wider end of the mask. A black l ine runs longitudinally

along the posterior aspect of the tube. At the machine end of the tube is a 15-mm

connector. The LMA is made from sil icone and contains no latex.


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View Figure

Figure 17.1LMA-Classic. Note the bars at the junction ofthe tube and mask. (Courtesy of LMA North America.)

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TABLE 17.1 Available LMA-Classics

LMA Size Patient Size

1 Neonates/infants up to 5 kg

1.5 Infants between 5 and 10 kg

2 Infants/children between 10 and 20 kg*

2.5 Children between 20 and 30 kg

3 Children 30 to 50 kg

4 Adults 50 to 70 kg


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5 Adults 70 to 100 kg

6 Adults over 100 kg

LMA, Laryngeal Mask Airway.*Size 2.5 may be more suitable for children of this size (16).

The classic laryngeal mask is available in eight sizes, as shown in Table 17.1. More

than one size should always be available, because the correct size cannot always

be predicted. When there is doubt, a larger rather than a smaller size should be

chosen for the f irst attempt (3).

Some studies have indicated that the appropriate size for most adult female

patients is number 4 while the most appropriate size f or adult males is 5

(4,5 ,6,7,8,9,10,11,12 ,13). Other studies found that both the size four and f ive may

be suitable for females (11 ,14 ). I t may be more appropriate to use a size 5 for l arge

adults and a size 4 for normal adults, regardless of gender (12,15 ).

Al te rnati ve formulas ba sed on we ight have been pro posed (17). A method to choose

the correct size laryngeal mask for children is to match the widest part of the mask

to the width of the second to fourth f ingers (18).

Too small an LMA wil l predispose to gas leaks during posit ive pressure venti lat ion.

Too large an LMA may tend to come up within the mouth, may interfere with

procedures in the mouth (5), and may also be associated with a higher incidence of

sore throat and other symptoms and a greater possibil i ty of pressure on t he l ingual

nerve.

I n s e r t i o n

Standard Technique

The standard insert ion technique uses a midline or sl i ght ly diagonal approach with

the cuff ful ly deflated (19 ,20 ,21 ,22). The head should be extended and the neck


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f lexed (snif f ing posit ion) (23). This posit ion is best maintained during insert ion by

using the noninsert ing hand to stabil ize the occiput (Fig. 17.2). The LMA can be

inserted without placing the head in this posit ion (24 ). The neutral posit ion may

cause a small decrease in successful placement compared with the snif f ing posit ion

(25,26,27). The jaw may be pulled down by an assistant to more fully open the

mouth.

The tube port ion is grasped as if i t were a pen, with the index f inger pressing on

the point where the tube joins the mask (Fig. 17.2). With the aperture facing

forward (and the black l ine facing the patient 's upper l ip), the t ip of the cuff is

placed against the inner surface

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of the upper incisors or gums. At this point, the tube should be parallel to the f loor

(23). I f the mouth is being held open, the jaw should be released during further

insert ion. In the patient with a restricted mouth opening an a lternative method is to

pass the LMA behind the molar teeth into the pharynx. The tubular part is then

maneuvered toward the midline (28 ).

View Figure

Figure 17.2Initial insertion of the laryngeal mask. Under

direct vision, the mask tip is pressed upward against thehard palate. The middle finger may be used to push thelower jaw downward. The mask is pressed upward as it is

advanced into the pharynx to ensure that the tip remainsflattened and avoids the tongue. The jaw should not be held

open once the mask is inside the mouth. The nonintubatinghand can be used to stabilize the occiput. (Courtesy of

Gensia Pharmaceuticals, Inc.)


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View Figure

Figure 17.3By withdrawing the other fingers and with aslight pronation of the forearm, it is usually possible to pushthe mask fully into position in one fluid movement. Notethat the neck is kept flexed and the head extended.(Courtesy of Gensia Pharmaceuticals, Inc.)

As th e LMA is ad vanced , the mask po rt io n is pres sed agains t th e hard pa la te by

using the index f inger. This means that the direct ion of applied pressure is dif ferent

from the direct ion in which the mask moves (29). I f resistance is felt , the t ip may

have folded on itself or impacted on an irregularity or the posterior pharynx. In this

case, a diagonal shif t in direct ion is often helpful, or a gloved f inger may be

inserted behind the mask to l i f t i t over the obstruct ion (30 ). I f at any t ime during

insert ion the mask fails to stay f lattened or starts to fold back, it should be

withdrawn and reinserted.

A chang e of direc t io n can be sensed as the mas k t ip en coun te rs th e posterio r

pharyngeal wall and follows it downward. By withdrawing the other f ingers as the

index f inger is advanced and slight ly pronating the forearm, it is often possible to

insert the mask fully i nto posit ion with a single movement (Fig. 17.3). I f this

maneuver is not successful, hand posit ion must be c hanged for the next movement.

The tube is grasped with the other hand, straightened slight ly, and then p ressed

down with a single quick but gentle movement unti l a definite resistance is felt (Fig.

17.4). This may co incide with anterior laryngeal displacement (30 ). The longitudinal

black l ine on the shaft should l ie in the midline facing the upper l ip. Any deviat ion

may indicate that the cuff is misplaced.

If the patient has a high, arched palate, a sl ight ly lateral approach may be needed.

The operator should check that the cuff t ip is correct ly f lattened against the palate

before proceeding (30 ). Dif f iculty encountered in negotiat ing the angle at the back


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View Figure

Figure 17.4The laryngeal mask is grasped with the otherhand and the index finger withdrawn. The hand that isholding the tube presses gently downward until resistance isencountered. (Courtesy of Gensia Pharmaceuticals, Inc.)

180-degree Technique

Another te chn iqu e is to ins ert the LMA wi th th e laryn gea l ape rtu re po int in g

cephalad and rotate it 180 degrees as i t enters the hypopharynx (45,81,82 ,83 ). A

dist inct pop may be felt by the introducing hand (81 ). This method may be as

satisfactory as the standard technique, especially in pediatric patients. I t has been

postulated that rotat ion of the bulky LMA cuff in the close proximity of the

hypopharynx could dislocate the arytenoid cart i lages (84 ).

Partial Inflation Technique

Yet another technique is to part ial ly or ful ly inf late the cuff before insert ion

(85,86,87,88 ,89 ,90). Although this technique may offer some advantages for an

inexperienced user, the device may frequently be malposit ioned (73 ,91). The

incidence of sore throat may be reduced with the partial inflation method ( 89 ).

Thumb Insertion Technique

The thumb insert ion technique is more suitable for patients where access to the

head from behind is dif f icult o r impossible. Insert ion is similar to the standard

technique except that the LMA

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is held with the thumb in the posit ion occupied by the index f inger in that technique.

As th e th umb nea rs the mouth, the f in ge rs are stre tc hed forward ov er th e pati en t' s


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face. The thumb is advanced to i ts ful lest extent. Before removing the thumb, the

tube is pushed into its f inal posit ion by using the other hand.

View Figure

Figure 17.5The laryngeal mask in place. (Courtesy ofGensia Pharmaceuticals, Inc.)

View Figure

Figure 17.6Laryngeal mask airway in place. The tip of themask rests against the upper esophageal sphincter while thesides face the puriform fossae.

T r ac h e al In t u b a t i o n w i t h t h e L MA -C l as s i c

The LMA can serve as a conduit through which a tracheal tube, stylet, or f iberscope

is passed (92,93,94,95,96,97 ,98,99 ,100). I t acts to posit ion the device over the

laryngeal aperture. The 30 angle between the tube and cuff was chosen because it

was found to be optimal for intubation through the LMA (10 1).


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3 6.0 cuffed 5.0

4 6.0 cuffed 5.0

5 7.0 cuffed 5.0

6 7.0 cuffed 5.0

LMA, Laryngeal Mask Airway; ID, internal diameter; OD, outer diameter.aIf the connector is removed, a larger tracheal tube can be inserted (104).

bA larger fiberscope may be accommodated if the aperture bars are removed (105).

Af ter the LMA is ins erted and f ixed into pos ition , the tra chea l tube is we ll lubricated

and inserted into the tube. Auscultat ing the end of the tube may be useful during

spontaneous breathing. The tracheal tube should be rotated 15 to 90

counterclockwise as i t is advanced to prevent the bevel f rom catching on the bars

at the junction of the tube and mask. A tracheal tube with a midline bevel point may

make this maneuver unnecessary. Once through the bars, the tracheal tube is

rotated clockwise, and the neck is extended to enable the t ip to pass anterior to the

arytenoids. The tracheal tube is then advanced unti l resistance is felt . The head is

then f lexed, permitt ing the tube to advance into the trachea.

An al ternate me thod of t rac he al intubatio n inc lu des load ing the lu bri cated tracheal

tube with the t ip placed at the level of the bars in the LMA so that when pushed

down, it will pass smoothly through the middle aperture ( 114).

I f the trachea is not entered init ial ly, i t is p ossible that the LMA is not well situatedover the laryngeal aperture or the epiglott is is blocking the aperture. Varying

degrees of neck f lexion and extension at the at lanto-occipital joint may be helpful

(111 ). I f the tube st i l l does not enter the trachea, it should be withdrawn unti l the

bevel is just behind the aperture bars. The LMA cuff should be

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deflated and the LMA pushed a litt le farther into the hypopharynx. This maneuver


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may cause elevation of the downfolded epiglott is. The tracheal tube is then pushed

downward.

Smaller tracheal tubes are easier to place than larger ones ( 115 ). I f the tube is not

large enough, it may be replaced by a larger tube by using a tube exchanger

(Chapter 19).

The LMA can be used to guide a stylet, bougie, or exchange catheter into the

trachea (42,95 ,99 ,116,11 7,118 ,119 ,120 ,121,122 ,123 ,124,125 ). It may be easier to

pass a stylet i f i ts angulated end is made to point anteriorly unti l i t passes through

the grill of the mask and then rotated 180 ( 126 ). Monitoring carbon dioxide through

a channel in the exchange catheter is a useful way of determining that the t ip is in

the trachea (127). After catheter placement is confirmed, the LMA can be withdrawn

and the tracheal tube inserted over the catheter.

F ib e r s c o p e G u i d e d

The LMA-Classic can be used to aid f iberoptic-guided intubation. The LMA is

inserted in the usual manner. The fiberscope, with a well-lubricated tracheal tube

and a fully deflated cuff threaded over i ts shaft, is advanced through the LMA. The

fiberscope is advanced into the trachea, and the tracheal tube is advanced over the

fiberscope into the trachea. The tube should be rotated as it is advanced. I t may be

useful to posit ion the tracheal tube in the LMA, just proximal to the aperture bars,

before inserting the fiberscope. A right angle bronchoscopic tracheal tube

connector with a seal is attached to the tracheal tube. This allows the f iberoptic

scope to be i nserted through the tracheal tube while the patient is being venti lated.

With this, posit ive end-expiratory pressure (PEEP) can be applied, which often

dramatically improves the view by stenting the collapsed upper airway (128)

Fiberscope size is important, especially in small pat ients. The maximum diameters

of scopes for various size tracheal tubes are given in Table 17.2.

The laryngeal mask has proved equal or superior to other devices designed to aid

with intubation using a f iberscope (129 ,130 ). This i ntubation method has been used

in infants as small as 3.6 kg (13 1). This method has a higher success rate than the

blind method and is associated with less risk of trauma or esophageal intubation

(96,132 ,133,134). An inspection of the tracheobronchial tree can be made. I t is

useful for patients in whom neck movement needs to be avoided (135).

A f ibers cop e ma y be us ed to insert a bo ugie or other gu ide into the tra che a th ro ugh

an LMA

(97,119 ,125,126,127 ,128 ,129,130,131 ,132,133 ,134,135 ,136,13 7,138,13 9,14 0,14 1,1


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42,143,144,145,14 6,147 ,148). The LMA can then b e removed and a tracheal tube

inserted over the guide. This technique allows a l arger tracheal tube to be placed

and avoids the danger of accidental extubation when the LMA is removed (97 ,143).

Re t r o g r a d e

The LMA can be used to facil i tate tracheal intubation by using a retrograde wire

technique (149,150 ,15 1) (Chapter 21). The guide wire is inserted through the

cricothyroid membrane and passed cephalad. A guide catheter is then threaded

antegrade over the wire. The LMA is then removed and a tracheal tube passed over

the catheter.

L i g h t e d S t y l e t G u i d e d

Tracheal intubation by using a l ighted stylet placed through a tracheal tube that is

inserted through an LMA-Classic has been described (152,15 3,15 4,155). The stylet

t ip is posit ioned at the pat ient end of the tracheal tube and is advanced through the

LMA. I f a central point of l ight in the anterior neck is observed, the LMA cuff is

suitably placed around the laryngeal inlet. I f transil lumination is not seen, the LMA

is reposit ioned in the pharynx according to the location of the l ight. Tracheal

intubation is accomplished by advancing the l ighted stylet unti l the suprasternal

notch is transil luminated. The success of intubation with this method is comparable

to blind intubation (15 5,156).

Na s o t r a c h e a l In t u b a t i o n

The LMA has been used to facil i tate nasotracheal intubation (15 7). The LMA is

inserted and a catheter placed in the trachea. Another catheter is inserted into the

nose and brought out through the mouth. The LMA is removed with the catheters in

place. The catheters are s utured together and tract ion applied to the nasal catheter

so that the cu rve in the mouth is removed. The tracheal tube is then inserted over

the catheters into the larynx.

Another metho d to pe rf orm na sotracheal in tu bation is to cu t a window in the

posterior aspect of the LMA's tube near the mask and remove the aperture bars

(158 ). A f iberscope mounted with a tracheal tube is inserted via the nose through

the window in the LMA and into the trachea.

Another metho d is to in sert the LMA and the n part ial ly wi thdra w the cuff into the

oropharynx, where it can s upply fresh gas to the spontaneously breathing patient

(159 ). Nasotracheal intubation is then accomplished by using a f iberscope.


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Problems Associated with Tracheal Intubation through the

LMA-Classic

Some standard tracheal tubes may not be long enough to insert through the LMA-

Classic (160). Deeper placement can be achieved by using a longer tracheal tube

(134 ,161,162,163 ,164,16 5,166 ,167 ,168,169 ,170 ,171 ,172,173 ,174 ), shortening the

LMA tube (139 ,175,176), removing the connector from the LMA, deflating the LMA

cuff (160 ) using a split LMA (92 ,102), or using a device such as a stylet to advance

the tracheal tube farther (108). Consideration should be given to using an airway

exchange catheter (17 7).

As th e trac hea l tube is pas sed th rough th e LMA -C las sic , the p ilot tube ma y be come

kinked (17 8).

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When intubating a pediatric patient with an uncuffed tracheal tube through an LMA-

Classic, the largest tube that wil l pass through the LMA may be too small to allow a

good seal during posit ive pressure venti lat ion. Leaving the LMA in place with the

cuff inf lated wil l reduce the leak (179 ). I f a cuffed tube is used, it may b e

impossible to remove the LMA without damaging the inflating device ( 18 0).

Cricoid pressure may make it more dif f icult to pass a tracheal tube

(38,181 ,182,183). I f intubation is ini t ial ly unsuccessful and intubation is deemed

vital, a second attempt should be made with transient release of cric oid pressure.

Changing from one-handed to bimanual cricoid pressure application may be helpful.

LMA-Classic Removal after Tracheal Intubation

The decision to remove the LMA-Classic after tracheal intubation or to leave it in

place depends on the circumstances. Reasons to remove the LMA include concern

about pressure on the soft t issues, the need to keep it away from the surgical f ield,

a possible increase in gastroesophageal ref lux, and dif f iculty in placing a gastric

tube (184).

Many users prefer to leave the LMA-Classic in place after intubation to provide an

alternative airway at the conclusion of the anesthetic (185 ,186,187 ). I f this is done,

the protruding end of the tracheal tube should be f irmly secured.

There is no simple way to remove the LMA without disturbing the trachea tube. An

LMA may be modif ied by split t ing the tube and cuff so that it can be more easily

removed over the tracheal tube (10 2,18 8). A small tracheal tube or other device


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may be placed in the end of the tracheal tube to act as a pusher (extender) to

prevent extubation as the LMA is withdrawn (94,18 9,190,191,19 2). A f iberscope,

bougie, jet stylet, or tube changer may be passed through the tracheal tube to

facil i tate reintubation if extubation occurs as the LMA is being removed (19 3).

LMA-Unique

The single-use LMA-Unique (disposable l aryngeal mask ai rway, DLMA) is shown in

Figure 17.7. Sizes are given in Table 17.3. I t is made of polyvinylchloride and costs

less than a reusable LMA. While the dimensions are identical to the standard LMA,

the tube is st if fer and the cuff less compliant. I t may be helpful to warm it prior to

insert ion to make it sof ter and more compliant.

Indicat ions are the same as for the LMA-Classic. I t may be a better choice for out-of-hospital or ward use, where it would be dif f icult to clean and s teri l ize a reusable

LMA after use. Insertion and placement of the LMA-Unique is similar to the LMA-

Classic. I f i t is used for f iberoptic intubation, shortening the tube may be helpful

(176 ).

Comparisons of the LMA-Unique with the LMA-Classic show litt le difference in ease

of insertion or performance (194 ,195 ,196 ), although the LMA-Unique may be

somewhat more dif f icult to insert (197 ). The intracuff pressure increases

signif icantly less in the LMA-Unique when nitrous oxide is used (198,199 ).

View Figure

Figure 17.7LMA-Unique.

One study found that a 3 -mm or 4-mm internal diameter (ID) tracheal tube could not

be inserted through the LMA-Unique (200). A structural problem result ing in a leak

has been reported (201 ).


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LMA-Flexible


The LMA-Flexible (wire-reinforced, reinforced LMA, RLMA, FLMA, f lexible LMA)

(Fig. 17.8) dif fers from the LMA-Classic in that it has a f lexible, wire-reinforced

tube (202,203,20 4). This tube is longer and narrower than the tube on the LMA-

Classic. I t is available in the s izes shown in Table 17.4. The cuff sizes are the

same as for the LMA-Classic. A single-use v ersion is also available. The sizes for

the single-use version are the same as for the mult iuse one.

TABLE 17.3 Sizes of the LMA-Unique

MaskSize

Patient Size(kg)

Maximum CuffVolume (mL of air )

Largest TrachealTube (ID in mm)a

Largest F lexibleEndoscope (ID in mm)b

1 Up to5

4 3.5 2.7

1.5 5 to 10 7 4.0 3.0

2 10 to

20

10 4.5 3.5

2.5 20 to

30

14 5.0 4.0

3 30 to

50

20 6.0 5.0

4 50 to70

30 6.0 5.0

5 70 to100

40 7.0 5.5


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ID, internal diameter.aIf the connector is removed, a larger tracheal tube can be inserted (104).bA larger fiberscope may be accommodated if the aperture bars are removed (105).

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View Figure

Figure 17.8LMA-Flexible. The wire-reinforced tube islonger and has a smaller diameter than the standard LMA.

The f lexible tube can be bent to any angle without kinking. This allows it to be

posit ioned away from the surgical f ield without occluding the lumen or los ing the

seal against the larynx. I t is less l ikely to be displaced during head rotat ion or tube

reposit ioning than the LMA-Classic.

I n s e r t i o n


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The LMA-Flexible is more dif f icult to i nsert than the LMA-Classic. A stylet, small

tracheal tube, or other device may be i nserted into the tube to st if fen i t

(205 ,206,207,208 ,209,21 0,211 ,212 ,213,214 ,215 ). The manufacturer recommends

that it be held between the thumb and index finger at the junction of the tube and

cuff and posit ioned by insert ing the index f inger to i ts ful lest extent into the oral

cavity until resistance is encountered. It may be necessary to use the other hand to

achieve full insert ion. I t may be easier to insert b y using the thumb, index, and

middle f ingers at the junction of the tube and bowl, then using the index and middle

f inger to advance it into the hypopharynx (21 6). A modif ied Magil l forceps or o ther

device may be useful (59 ,21 2,217 ). Other methods for insert ion have been

described (21 8). Some techniques such as the 180-degree technique may not work

with this LMA (202 ). After insertion, the tube may be brought out through the nose

(219 ).

Use

The LMA-Flexible is designed for use with surgery on the head, neck, and upper

torso where the LMA-Classic would be in the way. A throat pack should be used if

there is a r isk of dental fragments becoming wedged behind the cuff (202). I f

malocclusion test ing is needed, the tubing can be coiled inside the mouth (220).

Comparisons between the LMA-Classic and LMA-Flexible reveal that both are

similar in terms of mask posit ion, cl inical performance, and pharyngeal mucosal

pressures (22 1,222 ).

P r o b l em s

The wire reinforcement makes the LMA-Flexible more resistant to kinking and

compression than the LMA-Classic but does not prevent obstruct ion from bit ing.

Ai rway obs tructi on an d los s of sea l hav e been re po rte d wh en a Boyle Davis ga g

was used (223 ,224 ,225 ). This can usually be corrected by reposit ioning the gag.

The spiral reinforcing wire in the LMA-Flexible may become disrupted. Sometimes,

the disruption is internal and can only be discovered by looking carefully down the

shaft (22 6). Defects in the wire may c ause obstruct ion if the tube is bent, or pieces

of wire could break off and migrate into the tracheobronchial tree (22 6,227).

The small diameter of the tube l imits the size endoscope or tracheal tube that can

be passed through the LMA-Flexible (10 5). It has been recommended that

prolonged spontaneous venti lat ion be avoided because the smaller tube causes

increased resistance (202,228 ).


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The LMA-Flexible is unsuitable for magnetic resonance imaging (MRI) scanning if

image quality in the region of the LMA is important (229). The metall ic r ings wil l

cause image distort ion (22 9).

Malposit ion is less easily diagnosed with the LMA-Flexible than with the LMA-

Classic because the tube gives no c lear indicat ion of cuff orientat ion (23 0).

TABLE 17.4 Size Comparison between Standard and Flexible Laryngeal Mask Airways

LMA

Size

Patient Size

(kg)

LMA-Flexible

(ID in mm)

LMA-Classic

(I D in mm)

LMA-Flexible

Tube Length

(cm)

Maximum Cuff

I nfl ation Volume

(mL)

2 10 to

20

5.1 7.0 21.5 Up to 10

2.5 20 to30

6.1 8.4 23.0 Up to 14

3 30 to50

7.6 10.0 25.5 Up to 20

4 50 to70

7.6 10.0 25.5 Up to 30

5 70 to100

8.7 11.5 28.5 Up to 40

6 >100 8.7 28.5 23.5 Up to 50

LMA, Laryngeal Mask Airway; ID, internal diameter.

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LMA-Fastrach


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The LMA-Fastrach (intubating LMA, ILMA, ILM, intubating laryngeal mask airway)

was designed to overcome some of the l imitat ions of the LMA-Classic during

tracheal intubation (231,232,233,234 ,235 ,23 6,237,23 8). The LMA-Classic was too

floppy to optimize alignment with the glott is, and the long narrow tube could not

accommodate a standard tracheal tube. Another objective was to eliminate the

need to distort the anterior pharyngeal anatomy in order to v isualize the laryngeal

inlet, making the device applicable to patients with a history of dif f icult intubation

and a high or anterior larynx (234 ).


The LMA-Fastrach (Fig. 17.9) has a short, curved stainless steel shaft with a

standard 15-mm connector. The tube is of sufficient diameter that a cuffed 9-mmtracheal tube can be inserted and short enough to allow a standard tracheal tube

cuff to pass beyond the vocal cords. The metal handle is securely bonded to the

shaft near the connector end to facil i tate one-handed insert ion, posit ion

adjustment, and maintain the device in a steady posit ion during tracheal tube

insert ion and removal. There is a si ngle, movable epiglott ic elevator bar in place of

the two vert ical bars (Fig. 17.10A). A V-shaped guiding ramp is built into the f loor

of the mask aperture to di rect the tracheal tube toward the glott is. The t ip is sl ight ly

curved to permit atraumatic insert ion. Figure 17.10Bshows tracheal tube protruding

through the LMA tube and into the bowl.

The LMA-Fastrach does not contain latex. I t is available in sizes 3, 4, and 5. These

fit the same s ize patients as the LMA-Classic. Both reusable and disposable

versions are available.

I n s e r t i o n

The LMA-Fastrach was designed for use with the patient in the neutral posit ion

(231 ). This i ncludes using a head support, such as a pi l low, but no head extension.

The insert ion technique consists of one-hand movements in the sagit tal plane. I t

does not require placing f ingers into the patient 's mouth, thus minimizing the risk of

injury or infect ion transmission as well as allowing insert ion from almost any

posit ion (234,239 ).


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View Figure

Figure 17.9LMA-Fastrach with tracheal tube. The tube onthe LMA is shorter and wider than on the LMA-Classic andhas a metal handle. Note that the tracheal tube connector has

been removed. (Courtesy of LMA North America.)

The LMA-Fastrach should be deflated and lubricated in a manner similar to the

LMA-Classic. I t is held by the handle, which should be approximately parallel to the

patient 's chest. The mask t ip is posit ioned f lat against the hard palate immediately

posterior to the upper

P.471

incisors, then slid back a nd forth over the palate to distr ibute the lubricant. After

the mask is f lattened against the hard palate, i t is inserted with a rotat ional

movement along the hard palate and the posterior pharyngeal wall. The mouth

opening may need to be increased momentari ly to permit the widest part of the

mask to enter the oral cavity. The handle should not be used as a lever to force the

mouth open. As the mask moves toward the pharynx, it should be firmly pressed to

the soft palate and posterior pharyngeal wall to keep the tip from folding. The

curved part of the metal tube should be advanced without rotat ion unti l i t contacts

the patient 's chin, then kept in contact with the chin as the device is rotated inward.

The handle should not be used to lever upward during insert ion, because this wil l

cause the mask to press into the tongue.


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View Figure

Figure 17.10LMA-Fastrach. A:Note the single, movableepiglottic elevator bar and the V-shaped guiding ramp builtinto the floor of the mask aperture to direct the tracheal tubetoward the glottis. B:Tracheal tube emerging from theLMA.

When properly inserted, the tube should emerge from the mouth directed somewhat

caudally. Aligning the internal LMA-Fastrach aperture and the glott ic opening by

f inding the posit ion that produces optimal venti lat ion and then applying a slight

anterior l i f t with the LMA-Fastrach handle facil i tates correct posit ioning and blind

intubation (24 0).

The LMA-Fastrach can be inserted with a 180 rotation technique (24 1).

Use

Al though the LMA-Fas tra ch ha s been designed to fac i l i tate tra che al intu ba tio n, i t

can also be used as a primary airway device. I t is especially useful for the

anticipated or unexpected dif f icult airway

(231 ,240,242,243 ,244,24 5,246 ,247 ,248,249 ,250 ,251 ,252,253 ,254 ,255,256,25 7,25 8,

259,260 ,261 ,26 2,263,26 4,26 5,26 6,267,26 8,269).

Studies indicate that most insert ion attempts with the LMA-Fastrach are successful,

and a patent airway is secured in nearly all pat ients

(231 ,237,240,245 ,247,25 0,253 ,258 ,265,270 ,271 ,272 ,273,274 ,275 ). It has been

used successfully in children (276), morbidly obese patients (277,278 ,279), and

acromegalic patients (280).

The LMA-Fastrach can be inserted with the same or better success than the LMA-

Classic (28 1,282,28 3,284 ). It is easier to place than the LMA-Classic when manual

in-l ine stabil izat ion is used (285 ). However, in patients with limited neck movement,

intubation may be less l ikely to be successful and take longer than if a l ighted

intubation stylet is used (286 ).


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The LMA-Fastrach has been used successfully in the emergency department and

prehospital care (265,282,287 ,288,289 ,290 ). It can be used with the patient in the

lateral posit ion (291 ,292,293 ,29 4).

T r a c h e a l In t u b a t i o n

Muscle relaxants are not necessary for intubation through the LMA-Fastrach but

may increase the success rate (295 ,296 ,297,29 8,299 ). Cricoid pressure wil l

decrease the likelihood of success and may need to be released to allow intubation

(182 ).

The tracheal tube recommended by the manufacturer for use with the LMA-Fastrach

is a si l icone, wire-reinforced, cuffed tube with a tapered patient end and a blunt t ip

(236 ,300,301) (Chapter 19). This tube is f lexible, which allows negotiat ion aroundthe anatomical curves of the airway. I t has a high-pressure, low-volume cuff that

reduces resistance during intubation and makes cuff perforation as the tube passes

through the LMA less l ikely. There is a stabil i izer that allows the LMA to be

removed without extubating the patient.

When using the LMA-Fastrach, standard curved plast ic tracheal tubes are

associated with a greater likelihood of laryngeal trauma (302 ,303). Warming a

plast ic tube wil l result in success and complicat ion rates similar to that of the tube

from the LMA-Fastrach manufacturer (301 ). A s piral-embedded tube should not be

used. I f a curved plast ic tracheal tube is used, it may be helpful to orient the curve

opposite the LMA curve (265,272,303).

Whatever tracheal tube is used, i t is essential that it is possible to remove the

connector (304). I t is important to lubricate the tracheal tube well and pass it

through the LMA several t imes before use (305).

Blind Intubation

The patient's head is maintained in the neutral position. The tracheal tube

connector should be loosely f i t ted for easy removal. The tracheal tube should be

lubricated with a water-soluble lubricant and passed into the metal shaft of the

LMA-Fastrach unti l the tube t ip is about to e nter the mask aperture. With the

sil icone tracheal tube specially designed for the LMA-Fastrach, the longitudinal l ine

should face the handle of the LMA, and the tracheal tube should not be passed

beyond the point where the transverse l ine on the tube is level with the outer r im of

the LMA-Fastrach airway tube.

The LMA-Fastrach handle is grasped with one hand to steady it while the tracheal

tube is being inserted, then l i f ted l ike a laryngoscope (not levered) to draw the


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larynx forward a few millimeters. This increases the seal pressure and helps to

align the axes of the trachea and the tracheal tube. It also corrects the tendency for

the mask to f lex.

As i t is adv an ced into the LMA-Fas trach, the tube sho uld be rota ted an d mov ed up

and down to distr ibute the lubricant. Venti lat ion and carbon dioxide monitoring can

be performed during tracheal tube insert ion by connecting the tracheal tube to the

anesthesia breathing system.

The tracheal tube should be advanced gently. The LMA-Fastrach handle should not

be pressed downward. I f no resistance if felt , i t is l ikely that the epiglott ic elevating

bar is l i f t ing the epiglott is upward, allowing the tracheal tube to pass into the

trachea. When the tracheal tube is thought to be in the trachea, the cuff should be

inf lated and its posit ion in the trachea confirmed (Chapter 19).

I f the tracheal tube fails to enter the trachea, a number of problems may have

contributed to the lack of

P.472

success (234,270 ). The epiglottis may have folded downward, or the tube may have

impacted on the periglott ic structures. The LMA-Fastrach may be too small or too

large for the patient. The l arynx may have been pushed downward during insert ion.

There may have been inadequate anesthesia or muscle relaxation so that the vocal

cords were closed.

During blind tracheal intubation, the operator relies on tact i le perceptions,

especially a feeling of resistance, while advancing the tracheal tube (23 4). I f the

mask is not aligned with the glott ic opening or the size of the LMA-Fastrach is

inappropriate, resistance will be encountered as the tracheal tube tip pushes

against glott ic or periglott ic structures, such as the downfolded epiglott is,

valleculae, arytenoids, or aryepiglott ic folds.

If resistance is felt after the tracheal tube leaves the LMA-Fastrach, there are a

number of maneuvers that can be taken to relieve the situat ion. I f resistance is felt

at 2 cm beyond the 15-cm mark on the tracheal tube, it is l ikely that the tube has

impacted on the vestibular wall. Rotating the tracheal bevel may overcome the

impaction. Another problem at this level may be a downfolded epiglott is. Without

deflat ing the cuff, the device should be s wung outward for 6 cm and reinserted

(234 ). I f resistance is e ncountered 3 cm beyond 15 cm, the epiglott is may be out of

the reach of the elevating bar, and a larger LMA should be used. If resistance

occurs immediately after the tracheal tube leaves the LMA-Fastrach, the LMA may


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be too large and should be replaced with a smaller one (270). I f resistance is felt at

15 plus 4 cm, the LMA may be too large, and a smaller size should be used (239 ).

Other maneuvers that can be tr ied include slight ly rotat ing the LMA-Fastrach in the

sagit tal plane by using the metal handle unti l the least resistance to manual

venti lat ion is achieved, removing the head support, pull ing the metal handle toward

the user (extension), or pushing it away from the user (flexion) ( 237 ,240 ,258 ,265).

The LMA-Fastrach can be used to place an airway exchange catheter, which can

then be used to di rect a tracheal tube into the trachea (30 6).

Blind intubation using the LMA-Fastrach is faster than f iberoptic-guided intubation

or intubation using direct laryngoscopy (27 2,307 ). It can be performed awake (248 ).

When compared with awake f iberoptic intubation for patients with k nown dif f icult

airways, patient sat isfact ion was greater with the LMA-Fastrach (250 ).

The success rate of b lind intubation varies from 40% to 100%

(231 ,235,237,240 ,243,24 5,248 ,256 ,258,265 ,270 ,271 ,272,275 ,276 ,280,300,30 7,30 8,

309,310 ,311 ,31 2,313,31 4,31 5,31 6,317,31 8), depending on the number of attempts

and the experience of the operator.

The blind technique can be time consuming and may result in trauma or esophageal

intubation (23 7,245,27 1,30 9,31 0,31 2,31 9,320,321,32 2,32 3). I f dif f iculty is

encountered, the use of an LMA-CTrach should be considered.

Blind Nasal Intubation

Blind nasal in tubation can be accomplished (324 ). A f lexible tracheal tube is

inserted into the trachea through the LMA, which is then removed. A Foley catheter

is introduced into the nose and withdrawn from the mouth. The Foley catheter is

inserted into the end of the tracheal tube and inflated with saline to grip the inner

walls. The Foley catheter is then withdrawn unti l the machine end of the tracheal

tube exits through the nose.

Fiberscopic-guided Intubation

The LMA-Fastrach is useful for f iberoptic intubation in the dif f icult-to-intubate

patient (26 3). The f iberscope is used to observe correct tracheal tube passage

through the LMA. The epiglott ic elevating bar is too s t if f to be elev ated by a

f iberscope without r isk of damaging the t ip or direct ing it downward (239 ,325,32 6).

I t should be l i f ted by the distal end of the tracheal tube (32 7).

The tracheal tube is advanced approximately 1.5 cm past the mask aperture while

the intubating metal handle of the LMA-Fastrach is held to stabil ize it . The t ip of the

tracheal tube should now have lifted the fiberscope away from the bowl of the


25/260

mask, exposing the glott ic structures. The f iberoptic scope is inserted and

advanced to, but not beyond, the distal end of the tracheal tube. The tracheal tube

is advanced unti l the glott is is brought into view. The tracheal tube is then

advanced into the trachea.

If dif f icult ies are encountered, the patient 's head and neck may be maneuvered or

the LMA-Fastrach posit ion adjusted by using the metal handle (22 8).

Fiberoptic intubation has a high success rate (134,24 0,27 2,31 1,32 8). It can be

performed awake (257 ,261,32 9,330,33 1). I t has been used in patients with unstable

necks (261,32 8,33 0). I t is easier than intubation with a r igid laryngoscope or using

only a f iberscope in p atients with manual in-l ine stabil izat ion (259 ,328 ). It allows an

examination of the lower airway. I t can be performed easier and in less t ime if the

recommended tracheal tube is used (33 2).

During f iberoptic intubation with a size 3 or 4 LMA-Fastrach, venti lat ion may be

inadequate (333). With a s ize 5 LMA, venti lat ion is generally acceptable.

The LMA-Fastrach can be used with an optical stylet (334).

Light-guided Intubation

An i l lumina ted f lex ib le f iber or a ligh ted intub ati on style t in serte d through the

tracheal tube extending just beyond the tracheal tube tip can be used to guide a

tracheal tube into the glott ic opening

(247 ,270,291,292 ,308,31 0,312 ,322 ,335,336 ,337 ,338 ,339,340 ,341 ,342,343,34 4). A

dist inct central point of l ight without a halo in the midline indicates correct

placement. Once correct posit ion is achieved, the tracheal tube is advanced.

If resistance is felt , correct transil lumination is not observed or the l ight point is

seen moving laterally, the tracheal tube should be withdrawn 1 cm beyond

P.473

the epiglott ic elevator bar and one or more of the following adjust ing maneuvers

applied, depending on the cause of resistance and observation of the l ight before

each addit ional intubation attempt: f lexion or extension of the handle, withdrawing

the LMA-Fastrach by 5 cm followed by reinsert ion, performing manual venti lat ion

and adjust ing the LMA-Fastrach posit ion unti l the optimal seal is obtained, f lexing

the neck and extending the head, using a smaller tracheal tube, using a larger or

smaller LMA-Fastrach, or twist ing the L MA handle (27 0,32 2,33 5,33 6,338,340,34 5).


26/260

Light-guided intubation can decrease the time to successful intubation and the

number of attempts and failures when insert ing a tracheal tube through the L MA-

Fastrach compared with blind intubation (308 ,310,312,336,339,340).

Removing the LMA-Fastrach after Intubation

Af ter the tra che a ha s been intuba ted , the de c ision need s to be made whether to

remove the LMA-Fastrach or to leave it in place. It is usually recommended that the

LMA-Fastrach be removed (346,34 7,348). Alternately, the cuff can be deflated to 20

to 30 cm H2O and the LMA-Fastrach left in s itu (34 9). The LMA-Fastrach may exert

mucosal pressures in excess of capil lary perfusion pressure (34 8). Patients in

whom the LMA-Fastrach is retained have a higher incidence of hoarseness, sore

throat, and dysphagia (246,346).Removing the LMA is associated with a hemodynamic response (350). Delaying

removal for a few minutes may s light ly decrease the associated p ressor response

(273 ,351).

The tracheal tube needs to be stabilized to prevent extubation during LMA-Fastrach

removal. The tube connector needs to be removed. A stabil izer rod (extender) that

is placed in the end of the tracheal tube is available from the manufacturer (Fig.

17.11). Insert ing the t ip of a smaller tracheal tube into the end of the inserted

tracheal tube will allow ventilation while the LMA-Fastrach is being removed (35 2).

View Figure

Figure 17.11To stabilize the tracheal tube and to prevent

extubation during LMA-Fastrach removal, a stabilizer rod(extender) is placed in the end of the tracheal tube.

The LMA-Fastrach cuff is deflated, and the LMA-Fastrach is swung out of the

pharynx into the oral cavity while applying counterpressure to the tracheal tube

(239 ). The stabil izing rod is removed when the LMA-Fastrach cuff is clear of the


27/260

mouth. The tracheal tube is then f irmly grasped while unthreading the inf lat ion tube

and pilot balloon from the LMA-Fastrach. Finally, the tracheal tube connector is

replaced.

Problems with Intubation

Pharyngeal pathology may make intubation through the LMA-Fastrach impossible

(311 ,331,353).

Currently, the smallest size available of the LMA-Fastrach is the number 3. This

has been found to work well for intubation of patients over 30 kg, but for patients

under this weight, successful intubation through this device is less certain (313 ).

The LMA-Fastrach tracheal tube is expensive and should not remain in place for

long periods of t ime because it has a high-pressure cuff.The LMA-Fastrach requires more t ime for i ntubation and results in more esophageal

intubations and mucosal trauma than rigid laryngoscopy (309 ). Blind intubation

through the LMA-Fastrach generates cardiovascular responses s imilar to tracheal

intubation using direct laryngoscopy (309,35 0,354).

When the LMA-Fastrach is removed, the tracheal tube may be d isplaced downward

or dislodged (276 ).

P r o b l em s

The rigid LMA-Fastrach shaft cannot easily adapt to a change in the posit ion of thepatient 's neck. I t is more l ikely to be dislodged than the LMA-Classic if head or

neck manipulat ion is required. I t should not be used in cases where the patient wil l

be in the prone posit ion.

The LMA-Fastrach is unsuitable for use in the MRI unit .

A cas e of obs truct io n after the LMA -Fastra ch was ins erte d has bee n rep ort ed (355 ).

Fiberoscopy revealed that the epiglott ic elevating bar was in the laryngeal aperture,

and though it l i f ted the epiglott is, the arytenoid cart i lage was pressed anteriorly by

the LMA-Fastrach cuff, part ial ly obstruct ing the laryngeal aperture. Despite the

obstruct ion, the trachea was intubated successfully.

The large diameter of the LMA-Fastrach airway tube can cause dif f iculty during

insert ion in the patient with a l imited mouth opening and may put dentit ion at r isk

(356 ,357). Compared with the LMA-Classic, the L MA-Fastrach causes an increased

incidence of sore throat, sore mouth, and dif f iculty swallowing (358).

While LMA-Fastrach is easier to place than the LMA-Classic and placement is more

likely to be successful in

P.474


28/260

pat ients with immobil ized cervical spines (24 0,28 5,329), the LMA-Fastrach may

exert pressure on the cervical spine (348,35 9). Intubation through the LMA-

Fastrach may cause signif icant motion of the cervical spine. I t may be dif f icult to

insert in the patient with a cervical collar, especially if cricoid pressure is used

(256 ).

Anesthes ia prov ide rs who hav e l imi ted us e of the lef t arm wi l l fi nd th e LMA -

Fastrach dif f icult to use (360 ).

LMA-CTrach


The LMA-CTrach (Fig. 17.12) is si milar in construct ion to the LMA-Fastrach

(361 ,362). I t has two built- in f iberoptic channels, one to convey l ight from and the

other to convey the image to the viewer. These emerge at the distal end of the

airway tube under the epiglott ic elevating bar, which l i f ts the epiglott is as the

tracheal tube passes through the LMA-CTrach into the larynx. The fiberoptic system

is sealed and robust, so the LMA-CTrach can be autoclaved.

The monitor (viewer) is attached to the LMA-CTrach via a magnetic latch connector.

I t has controls for focusing and image adjustment. The viewer is battery operated.

The battery provides up to 30 minutes of continuous use and can be recharged.The LMA-CTrach is available in sizes 3, 4, and 5 and is reusable up to 20 t imes

(361 ).

View Figure

Figure 17.12The LMA-CTrach. It has two built-in

fiberoptic channels, one to convey light from and the otherto convey the image to the viewer. The monitor (viewer) is

attached to the LMA-CTrach via a magnetic latchconnector.


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Use

The LMA-CTrach is lubricated and inserted similar to the LMA-Fastrach without the

viewer attached (361 ). An antifogging solut ion should be applied to the optical l ens.

Af ter the LMA has bee n inserted , the airway sec ured, an d the pa tie nt ventilated, the

viewer is s witched ON and attached. A real-t ime image of the larynx is then

displayed. I f posit ioning is not sat isfactory, various maneuvers can be performed to

improve the view (361). After a s at isfactory glott ic aperture image is achieved, the

tracheal tube is advanced and viewed as it enters the trachea. Once the patient is

intubated, the viewer is detached and the laryngeal mask removed, leaving the

tracheal tube in place.

E v a l u a t i o n

The LMA-CTrach has poorer image quality than a f lexible f iberoptic endoscope. In

contrast to the view through a laryngoscope, the viewer provides visualizat ion from

the underside of the tracheal tube. I ts advantages include the abil i ty to align the

LMA outlet with the larynx and a high first intubation attempt success rate with

minimal neck movement. As with the LMA-Fastrach, the LMA-CTrach cannot be

used easily in the patient with a l imited mouth opening.

Tracheal intubation was successful at the f irst or s econd attempt in more than 96%

of patients, higher than blind intubation via the LMA-Fastrach (36 1,362 ). The viewmay be obstructed by secret ions, lubricant, or blood. I t has proved useful during

awake intubation in the presence of an unstable cervical spine (363).

LMA-ProSeal


The LMA-ProSeal (LMA-PROSEAL, PLM) (Fig. 17.13) has four main parts: the cuff,

inf lat ion l ine with pilot balloon, airway tube, and drain (gastric access) tube

(364 ,365,366,367 ). All components are made from sil icone and are l atex-free. I t is

available in six sizes (Table 17.5). Studies indicate that the size 4 is preferable for

P.475

most adult women and the size 5 f or most adult men (368 ,369).


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View Figure

Figure 17.13LMA-ProSeal. Note theintegral bite block.

TABLE 17.5 LMA-ProSeal

LMA

Size

Patient

Size (kg)

Maximu

m Cuff

Inflation

Volume

(mL)

Maximu

m Gastr ic

Tube Size

(French)

Maximu

m

Fiberopti

c Scope

Size (mm)

Length

of Drain

Tube

(cm)

Largest

Tracheal

Tube (ID in

mm)

1.5

5to10

7 10 18.2

4.0uncuffe

d

2 10to

20

10 10 19.0

4.0uncuffe

d

2.5

20to30

14 14 23.0

4.5uncuffe

d

3 30to50

20 16 26.5

5.0uncuffe

d


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4 50to

70

30 16 4 27.5

5.0uncuffe

d

5 70to

100

40 18 5 28.5

6.0cuffed

ID, internal diameter.

The airway (breathing, venti lat ion) tube of the LMA-ProSeal is s horter and smaller

in diameter than that of the LMA-Classic and is wire reinforced, which makes it

more f lexible. There is a locating strap on the anterior distal tube to prevent the

finger sl ipping off the tube and to provide an insert ion slot for the introducer tool.

An ac cessory ven t unde r the dra inage tube in th e bo wl prev en ts secre ti ons f ro m

pooling and acts as an accessory venti lat ion port. The LMA-ProSeal has a deeper

bowl than the LMA-Classic and does not have aperture bars. There is a bite block

between the tubings at the level where the teeth would contact the device.

The drain (drainage, esophageal drain) tube is parallel and lateral to the ai rway

tube unti l i t enters the cuff bowl, where it continues to an opening in the t ip that is

sloped anteriorly (Fig. 17.14). When the LMA-ProSeal is correct ly posit ioned, the

cuff t ip l ies behind the cricoid cart i lage at the origin of the esophagus. I t al lows

liquids and gases to escape from the stomach, reduces the risks of gastric

insuff lat ion and pulmonary aspirat ion, allows devices to pass into the esophagus,

and provides information about the LMA-ProSeal posit ion. The drain tube is

designed to prevent the epiglott is from occluding the airway tube, eliminating the

need for airway bars (368). A gastric tube, Doppler probe, thermometer,

stethoscope, or medication can be passed into the esophagus through the drainage

port (37 0,37 1,372,37 3,37 4). A plast ic support ing ring around the distal drain tube

prevents the tube from collapsing when the cuff is inf lated.


32/260

View Figure

Figure 17.14Patient end of LMA-ProSeal. The drain tubecontinues to an opening in the tip.

The LMA-ProSeal has a second dorsal cuff (Fig. 17.15). This pushes the mask

anteriorly to provide a better seal around the glott ic aperture and helps to anchor

the device in place (367 ). The dorsal cuff is not present on sizes 11/2 to 2

1/2. The

cuff is softer than that on an LMA-Classic. The ventral cuff is larger proximally to

improve the seal.

A silicone-c oated ma l le ab le me ta l in tr od uc er to fac il itate pl ac ement of the LMA -

ProSeal is available (Fig. 17.16). I t has a curved, malleable si l icone-coated blade

P.476

with a guiding handle. The distal end f its into the locating strap, and the proximal

end f its i nto the airway tube.


33/260

View Figure

Figure 17.15Posterior of the LMA-ProSeal, showing thedorsal cuff.

View Figure

Figure 17.16Metal introducer used to facilitate placementof the LMA-ProSeal.

I n s e r t i o nInsertion Methods

I t is recommended that the LMA-ProSeal cuff be deflated into a wedge shape, as

with the LMA-Classic. The patient should be in the snif f ing posit ion (lo wer neck

flexion and head extension). I t may be necessary to brief ly release cricoid pressure

to allow the L MA-ProSeal to pass (375 ).

In t r o d u c e r T ec h n i q u e


34/260


35/260

With this technique, a lubricated stylet, bougie, f iberoptic endoscope, suction

catheter, lightwand, or gastric tube is first placed through the drain tube

(366 ,378,379,380 ,381,38 2,383 ,384 ,385,386 ,387 ,388 ,389,390 ,391 ). The patient end

of the device is then inserted into the esophagus under laryngoscopic or f iberscopic

guidance. The bougie should be point ing posteriorly, opposite to when it is used for

intubation. The LMA-ProSeal is then advanced into place over the device. This

method avoids folding the t ip backward. I t is more successful and less traumatic

than using the introducer tool or digital me thods (381 ,385,388,392 ). This method

has been used for patients with known dif f icult airways (39 3,39 4), after failed

posit ioning of an LMA-Flexible (395 ), and to exchange an LMA-ProSeal (39 6).

Cuff InflationAf ter the LMA -ProSea l has be en inserted, th e cuff shou ld be inf la ted wi th enough

air to achieve an intracuff pressure of up to 60 cm H 2O. During insert ion and cuff

inf lat ion, the front of the neck s hould be observed to see if the c ricoid cart i lage

moves forward, indicat ing that the mask has correct ly passed behind it . The cuff

volume required for the LMA-ProSeal to f orm an effect ive seal with the respiratory

tract is lower than for the LMA-Classic (397 ). In fact, an adequate seal can be

obtained i n most patients with no air in the cuff; however, the cuff should be

inflated with at least 25% of the maximum recommended volume to ensure an

effect ive seal with the gastrointest inal tract (398).

Tests after Insertion

A smal l amou nt (1 to 2 mL ) of wa te r-b as ed gel or a soap bubble shou ld be plac ed

on the end of the drainage tube that protrudes from the mouth and posit ive

pressure applied to the airway tube (399 ,400 ,401,40 2,403 ). If the LMA-ProSeal is

properly placed, there should

P.477

be a slight up/down movement of the lubricant/soap. The soap bubble may move

when the lubricant gel does not ( 40 4). I f there is no movement or the bolus is

ejected, the mask may not be correct ly placed.

The drainage tube should be tested for patency. This can be done by passing a

gastric tube, a flexible endoscope, or a lighted stylet through the drainage tube

(405 ,406). Easy passage indicates c orrect posit ioning; dif f iculty suggests that the

mask should be reposit ioned, even if venti lat ion is sat isfactory.


36/260

The suprasternal notch tap test involves tapping the suprasternal notch or cricoid

cart i lage and observing simultaneous movement of the soap bubble at the proximal

end of the d rainage tube (36 6,40 0). However, this can produce both false posit ive

and false negative results (40 7).

Proper LMA-Proseal posit ioning can also be detected by insert ing a l ighted stylet

(406 ). I f the t ip is folded over, the stylet wil l meet resistance 1 to 2 cm from the t ip

of the drain tube.

Insertion Problems

Several malpositions for the LMA-ProSeal have been described, including

insuff icient depth, the t ip inserted into the glott is, the t ip folded backward, and

severe epiglott ic downfolding (408,409 ).I f the LMA-ProSeal is inserted to an insuff icient depth, there wil l be a poor seal. I f

a bubble of air is se en or the bolus of gel is ejected when the lungs are inf lated

with less than 20 cm H 2O, the respiratory and gastrointest inal tracts are not

isolated from one another. I f advancing the LMA-ProSeal does not correct the

problem, it should be removed and reinserted.

If the LMA-ProSeal has entered the v estibule of the larynx, venti lat ion may be

obstructed and gas may leak up the drainage tube or cause the gel in the drain

tube to move up and down with the cardiac rhythm (401 ,403 ). Pressure on the chest

leading to bubble formation confirms that the laryngeal vest ibule has been entered

(409 ). Advancing the mask deeper wil l exacerbate the obstruct ion. The mask should

be removed and reinserted (377).

I f the LMA-ProSeal t ip folds backward, the drain tube wil l be pinched off , leaving

the upper esophageal sphincter open (41 0,411 ,412 ,413). Aspirat ion of gastric

contents secondary to this malposit ion has been reported (414). The lubricant/soap

bubble at the end of the drain tube wil l not move, even with gentle tapping on the

suprasternal notch (39 9,40 0). This malposition may be associated with resistance

to insert ion, unexpectedly high inf lat ion pressures, and the bi te block port ion

protruding from the mouth. Inabil i ty to pass a gastric tube freely to the t ip of the

drain tube confirms the malposit ion. Several techniques may be used to correct the

situation, including reinsert ion with a lateral approach; reinsert ion with the drainage

tube st if fened by a gastric tube, bougie, or s tylet; bougie-guided reinsert ion; and

sweeping a finger behind the cuff (366 ).

Severe epiglott ic downfolding occurs when the epiglott is is dragged inferiorly and

completely covers the glott ic inlet. To correct this problem, the LMA-ProSeal should


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be reinserted with the head and neck in a more extreme snif f ing posit ion, with a jaw

thrust applied or with the epiglott is elevated by using a laryngoscope (366 ).

In s e r t i n g a Dev i c e t h r o u g h t h e D r a i n T u b e

The device to be inserted through the drain tube should be well lubricated and

passed slowly and c arefully, not forced. Warming the device may fac il i tate passage

(415 ). Some resistance may be felt where the drain tube angulates (41 6). It may be

helpful to use back-and-forth motions while insert ing a gastric tube to advance

lubricant into the curved segment and to ease passage through this port ion of the

drain tube (41 7). Inabil i ty to pass a gastric tube indicates mask misplacement

(407 ).

Suction should not be applied to the end of the drain tube as the LMA is beinginserted, because this may cause the drain tube to c ollapse and injure the upper

esophageal sphincter. Suction should not be applied to a gastric tube unti l i t has

reached the stomach. The gastric tube may be used to reinsert the LMA-ProSeal if

i t becomes displaced (38 0). The drain tube should not be c lamped.

A gas tric tu be ins erted th rough the LMA -ProSeal can be conv erte d to a nasoga stric

tube (418).

T r ac h e al In t u b a t i o n t h r o u g h t h e LMA - P r o S ea l

Tracheal intubation through the LMA-ProSeal requires a long narrow tracheal tubeor an a irway exchange catheter (41 9). After the LMA-ProSeal is removed, a larger

tube can be substituted, if necessary.

Use

The LMA-ProSeal can be used for both spontaneous and controlled venti lat ion, but

is more suited to controlled venti lat ion (409,420 ). The sealing pressure is higher

than with the LMA-Classic in adult and pediatric patients, making it a better choice

for situations where higher airway pressures are required, where better airway

protect ion is desirable, and for surgical p rocedures in which intraoperative gastricdrainage or decompression is needed

(364 ,365,397,398 ,411,41 3,421 ,422 ,423,424 ,425 ,426 ,427,428 ,429 ,430,431,43 2,43 3,

434,435 ,436 ,43 7,438,43 9,44 0,44 1,442). Case reports show no aspirat ion of gastric

contents despite regurgitat ion or v omit ing unless the LMA-ProSeal is malposit ioned

(414 ,436,443,444 ,445,44 6,447 ,448 ,449,450 ,451 ,452 ,453,454 ). However, aspiration

has been reported with malposit ioning (45 5).


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I t may be easier to place the LMA-ProSeal than the LMA-Classic during manual in-

l ine neck stabil izat ion (424 ). I t has been used in cases of known dif f icult airway

(428 ) and has been successfully used after fai lure with an LMA-Classic (375,427 ).

The LMA-ProSeal may be useful in cases where it is important to avoid airway

trauma, as it exerts lower pressures against the pharyngeal mucosa than the LMA-

Classic (39 7). However, airway trauma as evidenced by

P.478

blood on the device after removal is higher for the LMA-ProSeal than for the LMA-

Classic (40 9).

The LMA-ProSeal has been found to be s afe for use in an MRI unit , but imaging

quality may be compromised, depending on the pulse sequence that is used and

whether the area of interest is near the LMA (45 6).

P r o b l em s w i t h t h e LMA -P r o S e a l

The LMA-ProSeal is less s uitable as an intubation device than the LMA-Fastrach

because of the narrower airway tube. The fiberscope and tracheal tube sizes that

can be accommodated by the LMA-ProSeal are given in Table 17.5. The high

resistance associated with the smaller lumen may make it l ess suitable for use with

spontaneously breathing patients than other devices ( 45 7).

The LMA-ProSeal may be somewhat more dif f icult and take s light ly longer to insert

than the LMA-Classic in adults, although overall success is equivalent

(364 ,365,397,408 ,411,41 3,421 ,422 ,432,433 ,458 ). The incidence of intraoperative

complicat ions and postoperative sore throat are similar. In chi ldren, the ease of

insert ion is similar to the LMA-Classic (43 4,435 ,437,459 ). The LMA-ProSeal

requires a greater depth of anesthesia for insert ion than does the LMA-Classic

(460 ).

The LMA-ProSeal can cause airway obstruction after insertion, either by

compressing the supraglottic and glott ic s tructures or by cuff infolding (462 ,463).

Removing air from the cuff or p lacing the patient in the snif f ing posit ion may relieve

the obstruction.

Part ial upper airway obstruct ion during spontaneous v enti lat ion may result in

aspirat ing air through the drain tube into the esophagus (40 4,46 3). Esophageal

insuff lat ion can occur s imultaneously with venting from the drainage tube during

posit ive pressure venti lat ion with malposit ion (46 4,46 5). This may result in

inadequate venti lat ion.


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I t may not be possible to insert a gastric tube in some patients (466 ,467 ). This may

be due to select ion of too large a tube, inadequate lubricat ion, using a cooled

gastric tube, cuff overinf lat ion, or malposit ion (415).

The LMA-ProSeal is relat ively contraindicated for intraoral surgery because it

cannot be moved easily around the mouth, the drainage tube is vulnerable to

occlusion, and the larger proximal cuff could interfere with the surgical f ield (36 5).

The LMA-ProSeal has a shorter l i fe span than the LMA-Classic (468 )

Us i n g t h e LMA Fam i ly

An LMA of th e cho sen size plus on e s ize smal le r and larg er sho uld alwa ys be

immediately available. The sy ringe used to inf late the LMA should contain only air.

Inject ing organic substances such as propofol from a previously used syringe may

damage the LMA (469 ).

Preuse Inspection

V i s u a l In s p e c t i o n

The f irst s tep is to examine the tube. The airway tube should not be discolored, as

this would prevent seeing f luids that may enter the tube. There should be no cuts or

tears in the tube, and the spiral wires should not be kinked. The rest of the LMA's

external surface should be examined for damage such as cuts, tears, scratches, or

foreign part icles.

The interior should be free f rom obstruct ion or foreign part icles. The LMA-Flexible

should be examined to make certain that the reinforcing wire is wholly contained

within the wall of the tube.

The tube should be f lexed up to, but not beyond, 180. Kinking should not occur.

Bending the tube beyond 180 could cause permanent damage.

The next test is to examine the mask aperture. The bars should be gently probed to

make certain that they are not damaged and the space between them is free from

particulate matter. If the drain tube in the LMA-ProSeal bowl is torn or perforated,

the LMA should not be used.

The connector should f i t t ight ly into the outer end of the airway tube. I t should not

be possible to remove it easily. The connector should not be twisted. If the

connector has cracks or surface irregularit ies, i t should not be used.

De f l a t i o n / I n f l a t i o n

The next step is to withdraw air from the cuff so that the walls a re f lattened against

each other. Excessive force should be avoided. The cuff should not reinf late. The


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syringe should be removed from the inf lat ion valve and the cuff checked to make

certain that it remains deflated. I f i t reinf lates, there is a faulty valve or leaking

cuff. An LMA cuff with a hole may not reinflate after the air had been removed

(470 ).

The next step is to inf late the cuff with 50% more ai r than the recommended

maximum inf lat ion volume (Table 17.6).

The cuff should hold the pressure for at least 2 minutes. Any herniat ion, wall

thinning, or asymmetry is an indicat ion to discard the LMA. The balloon should be

ell ipt ical, not spherical or irregularly shaped. Excessive pilot balloon width

indicates weakness and imminent rupture. Failure to perform this test may miss

problems with the cuff (467 ,471 ).

Mask Preparation

The cuff should be fully deflated with a dry syringe to form a f lat oval disc (Fig.

17.17) This can be done by pressing the hollow side down against a c lean, hard,

f lat surface. The d eflated cuff should be wrinkle-free.

A cuf f-d ef lati ng too l is av ailabl e from the ma nu fac tu re r (Fig. 17.18). This device wil l

provide a superior and more consistent shape than either hand manipulat ion or free

deflat ion but does not offer any benefits in

P.479

terms of residual volume (472 ). The use of this device wil l lengthen the cuff l i fe

(473 ).

TABLE 17.6 Maximum Test Cuff Inflation Volumes


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Size LMA-Classic or LMA-

Unique (mL)

LMA-Flexible

(mL)

LMA-Fastrach

(mL)

LMA-ProSeal

(mL)

1 6

1.5 10

2 15 15

2.5 21 21

3 30 30 30

4 45 45 45 45

5 60 60 60 60

6 75 75

Lubricat ion should be a pplied to the posterior cuff surface cuff just b efore insert ion,

taking care to avoid gett ing lubricant on the anterior (bowl) su rface. The

manufacturer recommends water-soluble jelly and does not recommend the use of

analgesic-containing gels or sprays, because this may delay the return of protect ive

ref lexes and may provoke an allergic reaction. While some studies show that

lubricat ion with l idocaine gel or spray wil l result in a l ower incidence of retchingand coughing on emergence (87,47 4), another study showed increased intra- and

postoperative problems (475). Lubricants or sprays that contain si l icone may cause

the mask to soften and s well.


42/260

View Figure

Figure 17.17The laryngeal mask ready for insertion. Thecuff should be deflated as tightly as possible, with the rimfacing away from the mask aperture. There should be nofolds near the tip. (Courtesy of Gensia Pharmaceuticals,Inc.)

Anesthetic Induction

Insert ion of the LMA requires suff icient general or topical anesthesia to obtund the

airway ref lexes. A depth similar to that necessary for insert ing an oropharyngeal

airway but not as deep as is needed for tracheal in tubation is required (476).Abs ence of a mo to r respo ns e to a ja w thrust is a re liab le me thod for assessing th e

adequacy of anesthesia for LMA insertion (477). Greater depth is needed for

insert ing the LMA-ProSeal than for the LMA-Classic (46 0).

Awake Placement

The laryngeal mask can be inserted in an awake patient fol lowing topical

anesthesia of the upper airway and/or nerve blocks

(99,100 ,135,248,478 ,479 ,480,481,482 ,483). Mask insertion should be coordinated


43/260

with swallowing. I t may be helpful to part ial ly inf late the cuff to simulate a bolus of

food (484).

Cuff Inflation and Assessing Position and FunctionThe cuff should be inf lated to a pressure of approximately 60 cm H 2O (485,486 ). A

cuff pressure gauge is recommended for proper inflation pressure. Cuff pressure

can be est imated by feeling the tension in the pilot balloon. A spherical pi lot

balloon is an indicat ion that there is too much gas in the cuff.

The cuff should be inf lated over 3 to 5 seconds without holding the tube unless the

posit ion is obviously unstable (e.g., in edentulous patients with slack t issues). This

usually causes slight upward movement of the airway tube, and a s light bulging at

the front of the neck is commonly seen. There should be a smooth oval swell ing inthe neck and no cuff visible in the oral cavity.

The recommended maximum inflation volumes are given in Table 17.7. In pract ice,

it is rarely necessary to

P.480

use the full volume (30,485 ,487 ,488). Using greater-than-recommended volumes

wil l not improve the seal against the larynx and may worsen it (19 4). A rational

approach is to inf late the mask with half the maximum inf lat ion volume and to

determine the oropharyngeal leak pressure, adding more air i f necessary. Cuff size

is probably more important than inf lat ing volume in determining the seal, so

upsizing the LMA may provide a better seal than adding more air to the cuff of a

smaller LMA (10,16 ,489,49 0).


44/260

View Figure

Figure 17.18Cuff-deflating device for the Laryngeal MaskAirway. A:The laryngeal mask is inserted into the device.The cuff is deflated by using a syringe. At the same time,the device is compressed. B:After cuff deflation, the LMAis ready for insertion.

I f posit ive-pressure venti lat ion is to be used, the leak pressure should be greater

than 20 cm H2O (30 cm H 2O with the LMA-ProSeal). If spontaneous respiration is to

be used, the leak pressure should be greater than 10 cm H 2O. This is the

approximate pressure of f luid at the posterior pharyngeal wall i f the oral cavity is

flooded (49 1). Unti l spontaneous respirat ion has resumed, it may be helpful to

occlude the nose and seal the mouth around the tube to allow posit ive-pressure

venti lat ion (492 ).

The airway sealing pressure is determined by observing the pressure gauge in the

breathing system as the bag is squeezed and the pressure increases. Several

methods can be used to determine the leak pressure (493,494). A s tethoscope can

be placed just lateral to the thyroid cartilage. Another method is to listen over the

mouth for a noise when the bag is squeezed. Carbon dioxide may be detected by

placing the sample l ine in the oral cavity. Another method is determining a steady

airway pressure after closing the adjustable pressure l imit ing (APL) valve in the

circle s ystem.

It may be possible to improve the seal by adding more air to the cuff ( i f the

maximum recommended volume has not been injected) or by flexing or rotating the

head and neck slight ly (22 2,495,496). The leak pressure wil l be higher if the head

and neck are f lexed or rotated (222 ,433,497,498 ). Higher pressures may be

achieved by applying pressure on the front and/or side of the neck, by applying

continuous forward pressure on the LMA, or by lift ing the handle of the LMA-

Fastrach (499,50 0,501 ,502,503 ,50 4).


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Indications that the LMA is properly positioned include normal breath sounds, chest

movements, pressure-volume loops and volume monitoring not showing a leak , and

carbon dioxide waveforms with posit ive-pressure venti lat ion. I f the patient is

breathing spontaneously, normal reservoir bag excursions and absence of signs of

obstruct ion are indicat ions of proper

P.481

placement (506 ). A f iberscope or r igid endoscope can be inserted through the LMA

to confirm its posi t ion and rule out airway obstruct ion (73 ,79 ,10 9,506 ,507). X-ray or

MRI can also be used to confirm the posit ion (75,508 ). An esophageal detector

device can be used (50 9,510), although its ut i l i ty has been questioned (511).

TABLE 17.7 Maximum Cuff Dimensions

Mask

Size

Air Volum

(mL)

Maximum Bulge of

Cuff Ti p (mm)

Maximum Bulge of

Wide End of Cuf f (mm)

Maximum Transverse

Diameter of Cuff (mm)

1 6 7.8 8.6 26.3

1.5 10 9.5 10.2 32.6

2 15 11.5 13.0 39.0

2.5 21 13.0 14.5 45.0

3 30 14.8 16.6 51.2

4 45 17.0 19.0 58.5

5 60 21.1 22.4 68.3

I f the airway is obstructed, the cause may be incorrect mask posit ion, a downfolded

epiglott is, a closed glott ic sphincter, or an overinf lated cuff. In most cases,

removing and reinsert ing the mask wil l el iminate the obstruct ion. Another technique

is to l i f t the anterior neck structures by using a gloved hand inserted into the


46/260

mouth, deflate the cuff, and rotate the mask 360 (512). In some cases, the

epiglott is may be straightened digital ly (513). Jaw manipulat ion or reposit ioning the

head usually does not relieve airway obstruct ion. Removing air from the cuff may

be helpful (51 4). I f despite these efforts sat isfactory v enti lat ion cannot be achieved,

the device should be withdrawn and reinserted or a dif ferent size LMA or tracheal

tube should be used.

Fixation

A bi te bloc k or ro l l of gauze should be inserted into th e mouth bes ide th e tube to

prevent the patient from bit ing the tube and to i mprove stabil i ty. This is not

necessary with the LMA-ProSeal. Various other devices have been used

(515 ,516,517,518 ). An oropharyngeal airway should not be used, because both itand the LMA are designed to be placed in the midline, and the airway t ip might

compromise the LMA cuff or cause tube compression (519 ). Also, an oropharyngeal

airway may not prevent the tube from being bi t ten (121 ,520).

The tube should be secured with tape, taking care that it does not become twisted.

This can be accomplished by aff ixing the tape f irst to the maxil la, winding over the

cephalad side of the tube, and down around the caudal side to f ix the tube and bite

block f irmly to each other and to the opposite maxil la (521). Further security can be

provided by taping from zygoma to zygoma under the mandible (52 2) or around the

neck (52 3,52 4). A tracheal tube holder may be used (525 ). Other fixation methods

have been described (526 ,527 ). The f ixat ion method should not obstruct the

surgery. A suture around a tooth may be used if tape wil l be in the way.

Bending the tube against its natural curvature may cause it to become dislodged or

kink, unless the LMA-Flexible is used. Tract ion from the breathing system should

be avoided, and several methods to achieve this have been suggested (527,529).

Intraoperative Management

During surgery, airway patency and correct LMA orientat ion should be verif ied at

regular intervals. The patient 's upper abdomen should be periodically observed for

signs of distention and epigastric auscultat ion performed. A l ighter level of

anesthesia than would be required if a tracheal tube were used is usually possible.

I f laryngospasm, wheezing, swallowing, coughing, straining, or breath holding

occurs, anesthesia should be deepened or muscle relaxants administered. An

aerosol can be administered by using an LMA (530 ).

Nitrous oxide and carbon dioxide can dif fuse into the cuff, increasing intracuff

pressure and volume


47/260

(198 ,199,531,532 ,533,53 4,535 ,536 ,537,538 ,539 ,540 ,541,542 ,543 ,544). Cuff volume

increases less with the LMA-Unique than with the LMA-Classic ( 198 ). The increase

in volume may cause airway obstruct ion (514 ). Inf lat ing the cuff with n itrous oxide

wil l avoid this increase (54 5,546).

The manufacturer recommends that cuff pressure be checked periodically with a

pressure gauge, transducer, or other device ( Fig. 19.29) and adjusted to keep it at

approximately 60 cm H2O. The pilot balloon should feel compliant. I f the balloon

feels st if f or ol ive shaped, the pressure may be excessive. Others have suggested

that the logical method of controll ing cuff pressures during nitrous oxide anesthesia

may be to take the just seal p ressure as a control value and withdrawn volume to

maintain values close to this pressure ( 546).

The LMA can be used with controlled (including mechanical) or spontaneous

venti lat ion. Patient outcome has been found to be s imilar in nonparalyzed patients

with posit ive-pressure venti lat ion or spontaneous breathing (547). I f controlled

venti lat ion is used, the peak i nspiratory pressure should be kept below 20 cm H 2O

(30 cm H2O with the ProSeal). Higher pressures may result in a leak around the

mask, gastric distention, and operating room pollut ion (15 ,54 8,54 9,550 ,551,55 2).

Changes in the venti latory pattern to reduce t idal volume and using muscle

relaxants may result in a lower peak pressure. I f higher pressures are required,

considerat ion should be given to exchanging the LMA for a tracheal tube. I f cricoid

pressure is applied, the airway pressures at which the patient is venti lated can

often be increased to over 30 cm H2O without gastric insuff lat ion occurring (553 ).

Pressure control venti lat ion (Chapter 12), with or without PEEP, which is available

on newer anesthesia venti lators, may be the mode of choice for controlled

venti lat ion with the laryngeal mask because it al lows a lower peak pressure for the

same t idal volume with less leak around the LMA (439,55 4,555 ). For patients

breathing spontaneously, pressure-support venti lat ion i mproves gas exchange and

reduces the work of breathing (556,55 7). The work of breathing can also be

reduced by using CPAP (558 ).

A sudde n increas e in lea kag e, sno ri ng , o r ot her sounds often sign als the need for

more muscle relaxation, although other causes such as LMA displacement, l ight

anesthesia causing glott ic closure, airway obstruct ion, a leaking cuff, and a

decrease in lung c ompliance related to the surgical procedure are other possible

causes

P.482


48/260

(559 ). Adding air to the cuff wil l not al ways co rrect a leak and may make it worse

by increasing tension in the cuff and pushing it away from the larynx (560).

Sometimes, removing some air from the cuff wil l help.

I f regurgitat ion occurs, the f irst s ign may be the appearance of f luid traveling up the

LMA tube. Breath holding or coughing may occur. The patient should be placed in

the head-down position, the breathing circuit disconnected, and the airway tube

suctioned. I t may not be necessary to remove the LMA, although preparations for

tracheal intubation should be made and the patient intubated, if indicated.

Insert ing a nasogastric tube behind a non-ProSeal LMA can be aided by using a

nasal airway or a f lexible endoscope to displace the LMA forward (561).

Emergence from Anesthesia

I t is important that the bite block or roll of gauze be left in place unti l the LMA is

removed to maintain patency and prevent damage to the LMA (56 2,563 ). Cuff

deflat ion should be performed only when the LMA is removed (564 ,565). I f the cuff

remains inf lated as the LMA is removed, a greater mass of secret ions wil l also be

removed (566), but this technique increases the incidence of blood staining (but not

sore throat) (56 7). Taking off a glove tha t was worn when the LMA was removed

and invert ing it over the device wil l minimize the spread of contamination (56 8).

Keeping the LMA in place during transfer to the postanesthesia care unit (PACU)

wil l maintain a patent airway, while l eaving the anesthesia provider's hands free for

other tasks. During recovery, supplementary oxygen can be delivered with the L MA

in place by using a T-piece or other device

(569 ,570,571,572 ,573,57 4,575 ,576 ,577,578 ,579 ,580 ). With the T-piece, respirat ion

may be assisted manually by in termittently occluding the expiratory l imb (19).

There is controversy regarding the optimal t ime for LMA removal. I t should either

be removed with the patient in a deep level of anesthesia or when full recovery of

airway ref lexes has occurred. Leaving the LMA in posit ion unti l airway ref lexes

have recovered and the patient can phonate

chapter 17. supraglottic airway devices

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