peds anesthesia 2018 Rachel Flashcards by Sarah Horvath

pre-term

prior to 37 weeks gestational age

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neonate

1-28 days of life

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infant

28 days - 1 year

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child

> 1 year

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most significant transition occurs when?

first 24-72h after birth

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what are 4 main adaptive changes

establish FRC, convert circulation, recover from birth asphyxia, maintain core temo

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what is the % for fetal hb

70-90%

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what is the Hgb for full term neonate

18-20g/dl

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the fetal hgb shifts the oxyhemoglobin dissociation curve to the left, meaning…

increased 02 loading in the lungs/placenta, decreased unloading at the tissues. (remember left=love, right=release, so decreased unloading)

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what happens in the fetal lungs at 4 weeks

primitive lung buds develop from forgut

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what happens in the fetal lungs at 16 weeks

branching of bronchial tree complete to 28 divisions, no further formations of cartilaginous airways

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what happens in the fetal lungs at 24 weeks

primitive alveoli (saccules) and type 1 cells are present; surfactant is detectable, and survival is possible with artificial ventilation

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what happens in the lungs 28-30 weeks

capillary networks surrounds saccules; unsupported survival

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what happens in the lungs 36-40 weeks

true alveoli present, roughly 20 million at birth

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lungs birth - 3 months

pa02 rises are R to L mechanical shunts close

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lungs up to 6 years

rapid increase in alveoli at 350 million at age 6

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does guppy breathing in utero respond to chemical stimuli ?

yes

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what have fetal lamb studies shown

can remove all of the chemoreceptors and they will still breathe, but if you de-enervate the diaphragm, they will not breathe.

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normal ABG for mother at term

7.4 90 30

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normal ABG for umb vein placenta–> fetus

7.35 30 40

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normal ABG for umb artery fetus —> placenta

7.3 20 50

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normal ABG for newborn at 10 min

7.2 50 50

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normal ABG for newborn at 1 hr

7.35 60 30

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normal ABG for newborn at 24h

7.35 70 30

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the primary event for resp system transition is

initiation of ventiliation

in order to inflate the lungs what does the infant need

high negative pressure, -70mmHg

with the onset of ventilation, what happens to PVR and pulm blood flow

PVR decreases and blood flow increases

with the onset of ventilation what happens to PO2, CO2

Po2 up, CO2 down

what is the FRC in newborn

25-30ml/kg

why dont infants have lung collapse all of the time

because infants terminate the expiratory phase of breathing before reaching their true FRC which results in intrinsic PEEP and higher FRC

how to do you prevent lung collapse in an infant

want at least PEEP 5cm/h20

when is respiratory control system normal in neonate

3-4 weeks

how do infants respond to hypercarbia at birth

increasing ventilation, but the slope of the response curve is decreased.

hypoxia ___ the neonate's response to CO2

depresses

response to hypoxia is biphasic meaning

initial hyperpnea followed by depression of resp in about 2 min

what abolishes the initial hyperpneic response

hypothermia and low levels of anesthetic gases

by __ weeks of age, hypoxia produces sustained hyperventailiton

what is apnea of infancy defined as

resp pauses exceeding 20 sec or those accompanied by bradycardia or cyanosis

type 1 muscle fibers in diaphragm are __ and make up ___ in infant and ___ in adult

fatigue resistant , 25%, 55%

when the umbilical cord is cut, SVR is ___.

increased

during onset of breathing, PVR is ___

decreased

how many adults have a PFO

25-30%

physiologic closure of shunts happens in

10-15 hours

anatomic closure of shunts happens in

2-3 weeks

what are the 3 shunts

foramen ovale, ductus arteriosus, and ductus venosus

when shunts close, flow through FO and DA becomes __ to __

left to right

in utero, PVR is ___ and SVR is ___

high, low

born - PVR is ___ and SVR is ___

low, high

PPHN is

persistant pulm htn of the newborn.

PPHN is the persistence of ___ beyond the normal transition period in absence of ____

fetal shunting , structural heart defect.

etiology of PPHN is

hypoxia and acidosis

before anatomic closure of the fetal shunts, transient ____ to ____ shunting may occur in normal neonates during coughing bucking or straining during induction or emergence

right to left

PPHN tx

adequate ventilation and oxygenation - hyperventilation (maintain alkalosis), pulmonary vasodilators (prostaglandin), minimal handling, avoidance of stress

what is the function of the renal system in a fetus

passive production of urine which contributes to the formation of amniotic fluid.

2 characteristics of the fetal kidney

low renal blood flow, low GFR

the renal system in a neonate - systemic pressure is ___ and RVR is ___

low, high

newborn renal - systemic pressure ___ and RVR ___

rises, falls

by __ weeks all nephrons are developed

why cant an infant concentrate urine?

immature neonatal tubules do not completely reabsorb NA under teh stimulus of aldosterone - so the neonate will continue to excrete NA even in the presence of a severe Na deficit. neonate is an "obligate sodium loser"

urine osmolarity at birth

700-800

creatinine at birth

0.8-1.2 mg/dl

in the first week of life, what percentage of filtered NA can neonates conserve

70%

in the second week of life, what percentage of filtered NA can neonates conserve

neonate urine na level

20-25 meq/L

maintenance fluid for a baby should be

d5.2NS (need the glucose!)

lowest acceptable hct

35% because of high o2 demand with limited ability to increase CO

do not let hemoglobin fall below

___ ml/kg blood volume in term baby

___ ml/kg blood volume in pre-term baby

100

neonates and infants have an ___ blood volume and cardiac output per unit weight

increased

two stages of heat loss in an infant

transfer of heat from body core to skin surface (internal temp gradient) and dissipation of heat from skin surface to the environment (external heat gradient)

how do you prevent convection in a neonate

reduce air movement across body surface

how do you prevent radiation in a neonate

warm operating room - radiant lamps

how do you prevent evaporation in neonate

cover exposed body cavities, heat and humidify inspired gases

non shivering thermogenesis is metabolism of

brown fat

brown fat develops in the fetus between ____ weeks gestation

26-30

brown fat comprises ___% of the neonates total body

2-6%

non-shivering thermogenesis occurs with ___ stress and is mediated by the ___

cold, SNS

heat produced during non-shivering thermogenesis is a product of

fatty acid metabolism

cold stress causes ___ surfactant production which causes

decreased, collapse of alveoli and reopening of fetal circulation