Anesthesia Anesthesia AndAnd

The NeonateThe Neonate

Dr: M.A. ZaghloulDr: M.A. Zaghloul

Prof. of Anesthesia Prof. of Anesthesia

Ain-Shams UniversityAin-Shams University

Main differences Between Main differences Between

Adults and NeonatesAdults and Neonates

1- METABOLISM1- METABOLISM

The resting OThe resting O22 consumption of the neonate is double consumption of the neonate is double

that of the adult ( 6 ml/kg/min ).that of the adult ( 6 ml/kg/min ).

COCO2 2 production is also doubled.production is also doubled.

So pulmonary ventilation must be increased ( RR of So pulmonary ventilation must be increased ( RR of neonate is 50 ± 10 ).neonate is 50 ± 10 ).

If resp. obstruction occurs, neonates become seriously If resp. obstruction occurs, neonates become seriously hypoxic in about half the time than adults.hypoxic in about half the time than adults.

They are more susceptible to lack of food & water & They are more susceptible to lack of food & water & become more rapidly hypoglycemic & dehydrated.become more rapidly hypoglycemic & dehydrated.

Neonates have high resting C.O. to supply enough ONeonates have high resting C.O. to supply enough O2 2

& remove metabolites.& remove metabolites.

2- Respiratory System2- Respiratory System

Neonates are Neonates are obligate nasal breathers.obligate nasal breathers. The combination of small nares & large tongue, The combination of small nares & large tongue,

abundant lymphoid tissue, big head, short neck, abundant lymphoid tissue, big head, short neck, increases susceptibility of air way obstruction.increases susceptibility of air way obstruction.

The long, narrow, omega, shaped epiglottis & The long, narrow, omega, shaped epiglottis & more cephalad vocal cords makes more cephalad vocal cords makes intubation intubation more difficult.more difficult.

The narrowest part of upper airwayThe narrowest part of upper airway is opposite is opposite cricoid cartilage ( up to 10 years).cricoid cartilage ( up to 10 years).

A rough estimate of endotracheal tube size is:A rough estimate of endotracheal tube size is:

Diameter (mm) = Age/4 + 4 (above 4y)Diameter (mm) = Age/4 + 4 (above 4y)

OrOr

ID = ( 16 + age )/4 over 2 yID = ( 16 + age )/4 over 2 y

The length of neonatal trachea 2.5 cm.The length of neonatal trachea 2.5 cm. Nasal tubes need to be longer by 2 cmNasal tubes need to be longer by 2 cm. .

3- Pulmonary Ventilation3- Pulmonary Ventilation Because of horizontally placed, flexible ribs & Because of horizontally placed, flexible ribs &

relatively underdeveloped intercostal muscles relatively underdeveloped intercostal muscles they are diaphragmatic breathers & they are diaphragmatic breathers & susceptible to ventilatory embarrassment by susceptible to ventilatory embarrassment by abdominal distension.abdominal distension.

The diaphragm can fatigue under repeated The diaphragm can fatigue under repeated stress especially in prematures.stress especially in prematures.

The alveolar bed is incompletely developed at The alveolar bed is incompletely developed at birth, it reach adult type by 8 years.birth, it reach adult type by 8 years.

Tidal vol. are the same as in adults on terms Tidal vol. are the same as in adults on terms of cc/kg, but of cc/kg, but OO2 2 reserve during apnea is reserve during apnea is smaller .smaller .

Age dependent Respiratory variablesAge dependent Respiratory variables

NB 6m 1y 5y ANB 6m 1y 5y A

RRRR(b/min)(b/min) 50±10 30±5 24±6 18±5 1250±10 30±5 24±6 18±5 12

TV TV (ml)(ml) 21 45 78 270 575 21 45 78 270 575

MVMV(L/min)(L/min) 1 1.35 1.8 5.5 6.41 1.35 1.8 5.5 6.4

AVAV(ml/min)(ml/min) 385 - 1245 1800 3100385 - 1245 1800 3100

DS/TV DS/TV 0.3 0.3 0.3 0.3 0.30.3 0.3 0.3 0.3 0.3

OO2 2 consump.consump.6 -8 ml/kg/min 3-46 -8 ml/kg/min 3-4

PPa co2 (mmHg) 30 - 35 30 - 40 30 - 40

Pa O2 (mmHg) 60-90 80 -100 80 - 100

4- Heat loss & Temperature Controle4- Heat loss & Temperature Controle

There is increased heat loss & decreased There is increased heat loss & decreased

heat production up to 6m of age.heat production up to 6m of age.

A- HEAT LOSSA- HEAT LOSS Great surface area in relation to body weight.Great surface area in relation to body weight. Preterms has less subcutaneous fat.Preterms has less subcutaneous fat. Evaporation from exposed wound.Evaporation from exposed wound. Infusion of cold fluids. Infusion of cold fluids.

B- Heat productionB- Heat production

Newborns are unable to shiver.Newborns are unable to shiver. Reduced metabolism of brown fat & Reduced metabolism of brown fat &

carbohydrates due to block sympathetic carbohydrates due to block sympathetic system by GA.system by GA.

Hypothermia may cause difficulty in Hypothermia may cause difficulty in reversing muscle relaxants, hypoglycemia reversing muscle relaxants, hypoglycemia &. lactic acidosis&. lactic acidosis

5- CIRCULATORY SYSTEM5- CIRCULATORY SYSTEM

The resting C.O. is 2-3 times of adults.The resting C.O. is 2-3 times of adults. The resting H.R. is variable ( 110 – 160 ).The resting H.R. is variable ( 110 – 160 ). The resting blood volume is about 85 ml/kg.The resting blood volume is about 85 ml/kg. The haemoglobin is high (16 – 18 gm/100ml).The haemoglobin is high (16 – 18 gm/100ml).

Blood should be given if 10% of bl. vol. is lost Blood should be given if 10% of bl. vol. is lost & should be accurate.& should be accurate.

Give Ca gluconate (0.1 of 10% sol./10 ml bl.). Give Ca gluconate (0.1 of 10% sol./10 ml bl.).

Age Related Circulatory VariablesAge Related Circulatory Variables

NB 6m 1y 5y ANB 6m 1y 5y A

HRHR (b/min) (b/min) 133 120 120 90 75133 120 120 90 75

SBPSBP(mmHg) (mmHg) 80 90 96 95 12080 90 96 95 120

DBPDBP(mmHg) (mmHg) 46 60 66 55 80 46 60 66 55 80

SVSV(ml/b) (ml/b) 4.5 7.5 11.5 27.5 85 4.5 7.5 11.5 27.5 85

CICI(L/min/m(L/min/m22) ) 2.5 2 2.5 3.7 3.72.5 2 2.5 3.7 3.7

HbHb(g/dl) (g/dl) 16.5 11.516.5 11.5 12 12.5 1412 12.5 14

Normal & Accepted Hematocrit Normal & Accepted Hematocrit Value In Pediatric PatientValue In Pediatric Patient

Age Normal AcceptedAge Normal Accepted

( mean/range)( mean/range)

Premature 45 (40-45) 35Premature 45 (40-45) 35

NB 54 (45-65) 30 - 35NB 54 (45-65) 30 - 35

3m 36 (30-42) 253m 36 (30-42) 25

1y 38 (34-42) 20 – 251y 38 (34-42) 20 – 25

6y 38 (35-43) 20 - 256y 38 (35-43) 20 - 25

6- Water And Electrolyte Balance6- Water And Electrolyte Balance Water electrolyte turnover in neonate is 2 – 3 Water electrolyte turnover in neonate is 2 – 3

times of the adult.times of the adult. However the ability to deal with excess or However the ability to deal with excess or

deficiencies is less ( immature renal function).deficiencies is less ( immature renal function). Age And Distribution of Body WaterAge And Distribution of Body Water ECF ICFECF ICFNeonate 40% 35% of BWNeonate 40% 35% of BW

Adult 20% 40% of BWAdult 20% 40% of BW

7- Renal Function7- Renal Function Renal Function of Infants, Children & AdultsRenal Function of Infants, Children & Adults GFR U.cl. Urine exc.GFR U.cl. Urine exc. ml/min/1.73mml/min/1.73m2 2 ml/min/1.73mml/min/1.73m22 ml/24 h. ml/24 h.

Term Term 38.5 36 15 – 6038.5 36 15 – 606m 6m 110 22-46 250 – 450110 22-46 250 – 4501y 1y 117.5 17 500 – 600 117.5 17 500 – 6003y 3y 127 75 500 – 600127 75 500 – 600Adult Adult 127 75 500 – 600127 75 500 – 600

Neonates have difficulty in reabsorbing bicarbonate Neonates have difficulty in reabsorbing bicarbonate from their urine. Which results in from their urine. Which results in persistent persistent metabolic acidosis.metabolic acidosis.

By 6 m, renal function is 80 – 90 % of adult.By 6 m, renal function is 80 – 90 % of adult. Sodium loading & conservation is not efficient Sodium loading & conservation is not efficient

in neonates.in neonates.

Weight And Hourly Fluid requirementsWeight And Hourly Fluid requirements

Wt. (Kg) Fluid (ml/h) Wt. (Kg) Fluid (ml/h) < 10 4 ml/Kg< 10 4 ml/Kg 10 - 20 40 + 2 ml/kg > 1010 - 20 40 + 2 ml/kg > 10 > 20 60 + 1 ml/kg > 20> 20 60 + 1 ml/kg > 20

Fluid ReplacementFluid Replacement

Clinical situation vol.( ml/Kg/h)Clinical situation vol.( ml/Kg/h)

Intra-abdominal S. 2Intra-abdominal S. 2

Peritonitis/Perforation 4Peritonitis/Perforation 4

Two cavity S. 6Two cavity S. 6

• Halve of the deficit fluid is given in the Halve of the deficit fluid is given in the 11stst hour& the other ½ is divided equally hour& the other ½ is divided equally

in the subsequent 2 hoursin the subsequent 2 hours

Clinical Significance Of DehydrationClinical Significance Of Dehydration

Sig. Estimated vol. loss(%)Sig. Estimated vol. loss(%)

Poor skin turg., dry mouthPoor skin turg., dry mouth 5 5

Sunken font.,tachycard.,olig.Sunken font.,tachycard.,olig. 10 10

Sunken eyes & fontanel's 15 Sunken eyes & fontanel's 15 Coma 20 Coma 20

HYPOGLYCEMIAHYPOGLYCEMIA The 1The 1stst day of the baby have low BG level & low day of the baby have low BG level & low

glycogen stores in the liver.glycogen stores in the liver. It may be necessary to estimate BG conc. It may be necessary to estimate BG conc.

during anesthesia & give 10% G if needed. during anesthesia & give 10% G if needed. Normal BG of full term neonate is 60 – 80 mg/dlNormal BG of full term neonate is 60 – 80 mg/dl Hypoglycemia if < 30 mg/dl in FT.Hypoglycemia if < 30 mg/dl in FT. Hypoglycemia if < 20 mg/dl in preterm, which is Hypoglycemia if < 20 mg/dl in preterm, which is

common especially if BW< 2.5 Kg. common especially if BW< 2.5 Kg.

Caloric RequirementsCaloric Requirements

Up to 10 Kg = 100 cal/Kg/dayUp to 10 Kg = 100 cal/Kg/day 10–20 Kg = 1000 cal+50 cal/Kg/day 10–20 Kg = 1000 cal+50 cal/Kg/day for each Kg >10for each Kg >10

> 20 Kg = 1500 cal+20 cal/Kg/day > 20 Kg = 1500 cal+20 cal/Kg/day for each Kg >20for each Kg >20

Drugs In Pediatric AnesthesiaDrugs In Pediatric Anesthesia Always Remember That NB Has:Always Remember That NB Has: Higher metabolic rate.Higher metabolic rate. More water content, 75% ( more vol. of dist.).More water content, 75% ( more vol. of dist.). Less plasma & tissue protein.Less plasma & tissue protein. Lesser fat & muscle.Lesser fat & muscle. Large dist. of C.O. to vessel rich tissue.Large dist. of C.O. to vessel rich tissue. Uptake of inhalation agents is more rapid.Uptake of inhalation agents is more rapid. Diminished liver & kidney function.Diminished liver & kidney function. NB are sensitive to CNS depressants.NB are sensitive to CNS depressants. Intramuscular absorption is unreliable.Intramuscular absorption is unreliable.

Preoperative EvaluationPreoperative Evaluation

History:History:

course of preg. Mode of deliver, premature course of preg. Mode of deliver, premature labor, sickle cell dis.,…..labor, sickle cell dis.,…..

NB of IDDM have a sig. decrease in NB of IDDM have a sig. decrease in myocardial contractility in 1myocardial contractility in 1stst few days of life. few days of life.

There is sig. dep. Of neonates if the mother There is sig. dep. Of neonates if the mother received large doses of narcotics or MgSoreceived large doses of narcotics or MgSo33 . .

Evaluation of organ systems is necessary. Evaluation of organ systems is necessary.

Premedication Premedication

The only premedication is atropine < 10 Kg.The only premedication is atropine < 10 Kg.

Older children IM opiates + atropine or Older children IM opiates + atropine or hyoscine are commonly used.hyoscine are commonly used.

Ketamine is also commonly used in children Ketamine is also commonly used in children but not neonates.but not neonates.

Induction Of AnesthesiaInduction Of Anesthesia

Awake intubation.Awake intubation.

Inhalational induction.Inhalational induction.

IV induction.IV induction.

Maintenance Of anesthesiaMaintenance Of anesthesia

Inhalational + MR + CMV.Inhalational + MR + CMV.

Reverse MR at the end of surgery.Reverse MR at the end of surgery.

Awake extubation.Awake extubation.

Return to incubator.Return to incubator.

Monitoring Monitoring Precordial stethoscope.Precordial stethoscope. BP with suitable cuff size.BP with suitable cuff size. ( width of cuff = 2/3 length of arm )( width of cuff = 2/3 length of arm ) IBP through umbilical artery catheter in NB.IBP through umbilical artery catheter in NB. ECG.ECG. Oxygen saturation.Oxygen saturation. End-tidal COEnd-tidal CO2 2 .. Inspired OInspired O2 2 conc.conc. Temperature.Temperature.

Doses of Some Drugs Used InDoses of Some Drugs Used InPediatric AnesthesiaPediatric Anesthesia

Atropine 0.01mg/KgAtropine 0.01mg/Kg

Morphine 0.1mg/KgMorphine 0.1mg/Kg

Meperidine 1mg/KgMeperidine 1mg/Kg

Prostigmine 0.02 – 0.04 mg/KgProstigmine 0.02 – 0.04 mg/Kg + atropine 0.02 -0.03 mg/Kg + atropine 0.02 -0.03 mg/Kg

Caudal AnesthesiaCaudal Anesthesia

Use 23 gauge & ¾ inch long needle.Use 23 gauge & ¾ inch long needle. For cont. Epidural a 22 g cannula can be used.For cont. Epidural a 22 g cannula can be used. The dose of Lidocaine calculated by the The dose of Lidocaine calculated by the

equation: y = 0.056 × BW (Kg )equation: y = 0.056 × BW (Kg ) It produce analgesia up to T 6 – 8.It produce analgesia up to T 6 – 8. Or ½ ml/Kg of 1.5 % lidocaine.Or ½ ml/Kg of 1.5 % lidocaine. Infants have less toxicity than adults.Infants have less toxicity than adults.

Always Remember That:Always Remember That: Our 1Our 1stst responsibility in any critically ill patient is to responsibility in any critically ill patient is to

resuscitate & then give anesthesia as tolerate.resuscitate & then give anesthesia as tolerate.

NB feel pain as children & adults.NB feel pain as children & adults.

It is unacceptable technique to give only MR in It is unacceptable technique to give only MR in NB even if stable.NB even if stable.

Always monitor fluid balance and keep IV fluids warm.Always monitor fluid balance and keep IV fluids warm.