Pediatric Anesthesia

Question 1

Why do neonates and infants have a lower FRC? What else contributes to their faster desaturation?

Answer 1

Fewer and smaller alveoli (therefore decreased lung compliance); cartilaginous rib cage (very compliant chest wall) – this combination promotes chest wall collapse during inspiration and low residual lung volumes during expiration. Therefore, lower FRC - more predisposed to atelectasis and hypoxemia. This is exaggerated by higher rate of oxygen consumption.

Question 2

How is the neonatal and infant airway different than older children and adults?

Answer 2

• larger head and tongue
• narrower nasal passage
• anterior and cephalad larynx (glottis is at C4 instead of C6 like in adults)
• longer epiglottis
• shorter trachea and neck

Question 3

What is the narrowest point of the airway in children <5?

Answer 3

Cricoid cartilage (in adults, the glottis is the narrowest)

Question 4

Describe what is different about CO in neonates and infants (think HRxSV)

Answer 4

SV is relatively fixed bc of non-compliant and immature left ventricle. Therefore, CO is very HR dependent

Question 5

Why are neonates more susceptible to heat loss?

Answer 5

Thin skin, low fat content, greater surface area relative to weight

Question 6

What are the most important mechanisms of heat production in neonates

Answer 6

Metabolism of brown fat (limited in premature infants or sick neonates with low fat stores. Volatiles agents inhibit thermogenesis in brown adipocytes); shifting of hepatic oxidative phosphorylation to a more thermogenic pathway

Question 7

At what age does kidney function approach normal values?

Answer 7

6 months

Question 8

Why are neonates predisposed to hypoglycemia? what are other risk factors in neonates for hypoglycemia?

Answer 8

Reduced glycogen stores.

Risk factors: premature, small for gestational age, diabetic mothers, receiving hyperalimentation

Question 9

What is the pediatric dose for atropine?

Answer 9

0.01-0.02mg/kg IV
0.02mg/kg IM
Minimum dose 0.1 mg

Question 10

What is the pediatric dose for diphenhydramine?

Answer 10

1mg/kg IM/IV/PO

Question 11

What is the pediatric dose for epinephrine bolus? endotracheal?

Answer 11

10mcg/kg bolus

100mcg/kg ETT

Question 12

What is the pediatric dose for fentanyl - pain and anesthetic induction?

Answer 12

Pain: 1-2mcg/kg

Anesthetic adjunct: 1-5mcg/kg

Question 13

What is the pediatric dose for ketamine induction? (IV and IM)

Answer 13

1-2mg/kg IV

6-10mg/kg IM

Question 14

What is the pediatric dose for ketoralac?

Answer 14

0.5-0.75mg/kg

Question 15

What is the premedication dose for midazolam? What is the max dose?

Answer 15

0.3-0.5mg/kg po

Max = 20mg po

Question 16

What is the pediatric dose for morphine for pain relief?

Answer 16

0.025-0.1mg/kg

Question 17

What is the pediatric dose of ondansetron?

Answer 17

0.1mg/kg IV

Question 18

What are the pediatric doses for rocuronium and succinylcholine?

Answer 18

Roc: 0.6-1.2mg/kg
Sux: children: 1-1.5mg/kg; infants: 2-3mg/kg
Sux IM: 4-6mg/kg)
*Should always premedicate with atropine if giving sux (0.1mg min; 0.02mg/kg if IM)

Question 19

What is the pediatric dose for cefazolin?

Answer 19

25mg/kg IV

Question 20

How does volume of distribution change with age?

Answer 20

Because total body water content decreases with age, so does volume of distribution. It is greatest in neonates.

Question 21

Why is induction speed with volatile anesthetic faster in infants and younger children?

Answer 21

Greater alveolar ventilation and reduced FRC

Question 22

How do MAC values compare for neonates, infants, small children and adults?

Answer 22

Highest MAC in infants, then then neonates, then small children, then adults

Question 23

Why do infants and young children require higher propofol doses?

Answer 23

greater volume of distribution. They also have a shorter elimination half-life and higher plasma clearance for propofol

Question 24

How does opioid potency compare in neonates vs older children/adults

Answer 24

More potent in neonates. Morphine in particular should be used with caution (particularly repeated doses) because reduced hepatic conjugation and renal clearance

Question 25

What are the worries with given succinylcholine to a child versus an adult?

Answer 25

• may have profound bradycardia and sinus node arrest following 1st dose (if no atropine pretreatment)
• more susceptible to cardiac arrythmias, hyperkalemia, rhabdo, myoglobinemia, masseter spasm and MH

Question 26

Where should the sat probe be placed on a neonate?

Answer 26

right hand or earlobe (pre-ductal)

Question 27

Describe fetal circulation, starting with blood entering from the placenta

Answer 27

Oxygenated blood from the placenta enters the IVC via the umbilical vein and mixes with deoxygenated blood from lower limbs. IVC to the R Atrium via ductus venosis. From R Atrium preferentially crosses the foramen ovale to L Atrium. L atrium to L ventricle and the oxygenated blood then perfuses brain and upper extremities. Blood returns via SVC and preferentially enters RV. RV to pulmonary artery, then given high pulmonary pressure 95% of blood is shunted across ductus arteriosis down the aorta and to lower body and the placenta. The blood that comes from placenta that does not pass through ductus venosis mixes with blood from portal vein and perfuses liver before entering heart

Question 28

What is the relative amount of SV of each ventricle in fetal circulation?

Answer 28

RV 2/3rds LV 1/3rd

Question 29

At what fetal age is there sufficient pulmonary surfactant?

Answer 29

34 weeks gestation