3 Cheng KS, NG JM. Airway loss during

tracheostomy. Canadian Journal of

Anesthesia 2002; 49: 110.

Simple monitoring of cufftracheal pressures

In 1984 Seegoblin and Hasselt exam-

ined tracheal cuff pressure and mucosal

blood flow [1], recommending that cuff

inflation pressure should not exceed

30 cm H2O ⁄ 22 mmHg. Adequacy of

cuff inflation is conventionally deter-

mined by palpation of the external

balloon. Previous studies suggest that

this approach is unreliable; Fernandez

et al. [2] found that accuracy for esti-

mation by this method was 69% for

high pressures and 73% for low pres-

sures. Under-inflation is also deleteri-

ous. Micro-aspiration of secretions can

occur, leading to ventilator associated

pneumonia. When not measured, staff

are more likely to over-inflate cuffs to

prevent these problems [3].

We conducted a two-phase audit

cycle over 6 months, separated by a

clinical intervention. The phases

involved a survey of tracheal cuff pres-

sures on the Intensive Care Unit at

Wrexham Maelor Hospital, Wrexham,

UK. Fifteen consecutive patients were

monitored in each phase; cuff pressures

were recorded on admission (or on

intubation) and 24 h after intubation.

Pressures were measured by the same

investigator using an inflation-deflation

device (Portex, Smiths Medical Inter-

national, Watford, Herts, UK). Pressure

was measured during the inspiratory

phase. One month after completion of

phase one, the following clinical inter-

ventions took place: cuff pressure mea-

surement devices were made available at

each bedside; staff were trained in their

use; and twice daily measurements of

cuff pressure were made, and the mea-

sure incorporated onto daily record

chart. Re-audit (phase two) took place

one month following this intervention.

The data were compared, examining

two main elements: magnitude of dif-

ference between measured cuff pressure

and recommended pressure; and intra-

patient variability in cuff pressure over

24 h. The desirable range chosen for

audit purposes was set at 18–24 mmHg.

Before clinical intervention 12 out of 15

patents had an initial cuff pressure over

the desired range. On average these

pressure were 19 mmHg above the

upper acceptable limit. In phase two,

once again 12 out of 15 patients’

pressures were out of the desirable

range but on average these pressures

were only 8 mmHg above the upper

limit. In phase two the range of cuff

pressures seen was smaller at 22–

38 mmHg (range of 16 mmHg) com-

pared to the range of pressures seen in

phase one: 18–68 mmHg (range of

50 mmHg). Data from both phases

were also compared with regard to

intrapatient cuff pressure variability over

the 24 h studied. During phase one,

pressures differed, on average, by

9 mmHg over 24 h for any individual

patient. This figure fell to 3 mmHg in

phase two.

Numerous articles conclude that reg-

ular cuff pressure monitoring is key in

maintaining pressures within certain

limits [3–5]. This audit supports these

findings. We found reduced variability

in cuff pressure in individual patients

over 24 h, something less emphasised in

the literature. We suggest that regular

cuff pressure monitoring creates a

smoother profile in cuff pressure for

individual patients. Few studies examine

the significance of fluctuations in tra-

cheal cuff pressure with relation to

mucosal blood flow. The avoidance of

wide fluctuation in an individual’s tra-

cheal cuff pressure may prevent an

ischaemia-reperfusion-ischaemia cycle

affecting tracheal mucosa.

D. Huckle

P. Hughes

Wrexham Maelor Hospital

Wrexham, Wales, UK

E-mail: daniellehuckle009@hotmail.com

References1 Seeglobin RD, Hasselt GL. Endotra-

cheal cuff pressure and tracheal mucosal

blood flow, endoscopic study of effects

of four large volume cuffs. British

Medical Journal 1984; 288: 965–8.

2 Fernandez R, Blanch L. Endotracheal

cuff pressure assessment: pitfalls of fin-

ger estimation and need for objective

measurement. Critical Care Medicine

1990; 18: 1423–6.

3 Vyas D, Inweregbu K, Pittard A.

Measurement of tracheal cuff pressure

in Critical Care. Anaesthesia 2002; 57:

275–7.

4 Braz JR, Navarro LH, Takata IH,

Nascimento Junior P. Endotracheal cuff

pressure: need for precise measurement.

Sao Paulo Medical Journal 1999; 117:

243–7.

5 Jaber S, El Kamel M. Endotracheal cuff

pressure in intensive care unit: the need

for pressure monitoring. Intensive care

Medicine 2007; 33: 917–8.

Do we do as we say we do?

Questionnaires that involve surveys of

clinical practice are widely used for data

collection in the National Health

Service. In our experience, they are

enthusiastically thrust into our pigeon

holes and e-mail inboxes with alarming

regularity. We were interested in the

reliability of results obtained in this way,

so we e-mailed the authors of five postal

surveys to ask if they had been able to

verify their results. We received three

responses all confirming that they had

not.

Poorly designed studies with ill

defined targets, insufficient sample size

and ambiguous questions resulting in a

low response rate are just some of the

potential pitfalls. In addition to these,

we would like to pose the question ‘do

we actually do what we say we do?’ If

the answer is ‘no’, then even the most

robust survey will fail because the results

are fundamentally flawed. We are not

suggesting that responses are deliber-

ately intended to be dishonest or mis-

leading, rather that they are reflections

of our best intentions that we may or

may not fulfil.

In an attempt to assess the value of

questionnaires, we carried out a simple

two-part study of fresh gas flow rates

used with the circle system during

anaesthesia. The first part involved the

discrete observation of the fresh gas

flow being used by 51 permanent

members of staff in a teaching hospital.

The fresh gas flow was recorded when

the anaesthetist concerned was seated

and writing the notes (approximately

30 min into the case) as we assumed

this indicated the anaesthetist was

Anaesthesia, 2010, 65, pages 207–217 Correspondence......................................................................................................................................................................................................................

� 2010 The Association of Anaesthetists of Great Britain and Ireland 215

satisfied with the settings. This was

repeated for the same 51 anaesthetists at

a later date in order to obtain a mean

figure. The second part of the study

involved a questionnaire sent to the

same 51 anaesthetists asking what fresh

gas flow they would use when anaes-

thetising a patient with the circle

system.

The data for both parts of the study

were completely anonymous and there-

fore comparison between individual

stated and actual fresh gas flow was

not possible, but as we were able to

obtain a 100% response to the ques-

tionnaire this ensured that group com-

parison was valid. Our findings were

plotted on a graph and a median (IQR)

was obtained for both stated and

observed fresh gas flow. We found that

the written results revealed a median

(IQR) fresh gas flow of 1.5 (1-2)

l.min)1. However in the observed

results, the median (IQR) value for

fresh gas flow was 2 (1.5-3) l.min)1.

The graph (Fig. 1) illustrates the dis-

crepancy between the two sets of data

much more clearly.

There is undoubtedly potential for

error in the observed results as we had

to assume maintenance fresh gas flow

had been set. Furthermore, we were

unable to establish whether there were

extenuating circumstances as this would

have revealed that a survey was being

carried out.

Consent for the secret observations of

the first survey could not be obtained

from each individual as this would have

invalidated the survey. The project was

discussed with the clinical service direc-

tor and the lead consultant for audit,

and permission was given for it to be

completed for internal presentation.

Subsequently, after presentation to the

department, retrospective consent was

given for publication for which we are

most grateful.

W. King

J. Kemp

M. Crosse

Portsmouth Hospitals NHS Trust

Portsmouth, UK

Poole Hospital NHS Trust

Poole, UK

Southampton University Hospital

NHS Trust Southampton, UK

E-mail: wendyking@doctors.org.uk

An unseen obstruction

A 9-year-old child required general

anaesthesia for laparotomy. Surgery

and intra-operative anaesthesia were

uneventful. The child’s trachea was

extubated and oxygen was administered

via a size-3 Intersurgical facemask

(Wokingham, Berkshire, UK). Carbon

dioxide was not observed on capnogra-

phy and the child’s breathing pattern

was clearly obstructed. Airway manoeu-

vres were performed with the addition

of a small amount of positive end-

expiratory pressure to counter any pre-

sumed laryngospasm.

A second anaesthetist arrived at this

point to start the next operating list and,

standing adjacent to the first, noticed

that fogging was occurring: not in the

mask as it should but over the nose and

mouth. This was un-observable from

the first anaesthetist’s position at the

head of the patient. The mask was

removed and the plastic backing of a

SkintactTM ECG electrode (Skintact,

Gloucestershire, UK) was found adher-

ent to the inside of the mask, perfectly

occluding the internal aperture. It was

removed, oxygen successfully delivered

to the patient, with immediate resolu-

tion of the obstructed breathing. The

child remained 99% saturated through-

out and suffered no adverse sequelae.

Anaesthesia related complications are

not uncommon in the paediatric pop-

ulation [1], occurring at a rate of

between 2.4% and 8.6% of anaesthetics,

varying with age [2], with the highest

complication rates in children under the

age of three [3]. Marcus found that

42.5% of in-theatre incidents during

paediatric anaesthesia were due to hu-

man factors, the most common of

which were errors in judgement, fol-

lowed by failure to check equipment

[2]. The disastrous consequences of

equipment failure was highlighted by

the 2001 case from the Broomfield

Hospital in Essex, where a 9-year-old

child for routine minor surgery died as a

result of an intravenous line cap that was

occluding the anaesthetic circuit. This

case, and ten others like it, prompted a

formal police investigation (Operation

Orcadian), a response from the Depart-

ment of Health [4] and guidelines from

the Association of Anaesthetists of Great

Britain and Ireland [5].

Although we had checked our equip-

ment at the beginning of the case in

accordance with the published guide-

lines, the colourless ECG electrode

backing, with residual adhesive, had

been accidentally discarded into the tray

intended for the mask and laryngo-

scope, coming into contact with the

facemask and causing complete obstruc-

tion. Had a second pair of eyes, observ-

ing the events from a different angle,

not been present, the problem may not

have been resolved so quickly. To our

knowledge this is the first time a case

such as this has been reported and it

highlights the need for constant vigi-

lance, not just with equipment, but also

when discarding unwanted items.

B. Stanley

P. Roe

Cambridge University Hospital NHS

Foundation Trust

Cambridge, UK

E-mail: paul.roe@addenbrookes.nhs.uk

Figure 1 Questionnaire responses ( ) and observed fresh gas flow ( ).

Correspondence Anaesthesia, 2010, 65, pages 207–217......................................................................................................................................................................................................................

216 � 2010 The Association of Anaesthetists of Great Britain and Ireland