Pediatric Anesthesia Flashcards
Is pyloric stenosis considered an emergency?
Yes
prior to 37 weeks gestational age
pre-term
1-28 days of life
neonate
28 days to 1 year
infant
> 1 year
child
most significant part of transition occurs within the first ___ to ____ hours after birth
24 to 72
________ changes occur in all organ systems
adaptive
Adaptive changes (4)
establish FRC, convert circulation, recover from birth asphyxia, maintain ccore temperature
During fetal respiration, gas exchange occurs in the ______. 02 transport is accomplished by fetal hemoglobin which totals ____ to ___%.
placenta / 70 - 90%
Fetal Hgb shifts the oxyhemoglobin dissociation curve to the ______.
Left / increased 02 loading in the lungs/placenta, decreased 02 unloading at tissues
02 unloading adequate for fetus becomes insufficient after _______
birth
Hgb of full term neonate
18-20 g/dL
Lowest acceptable hemoglobin on a child under the age of 1 is what?
10
Fetal lung at 4 weeks
primitive lung buds develop from foregut
fetal lung at 16 weeks
branching of bronchial tree complete to 28 divisions, no further formation of cartilaginous airways
Fetal lung at 24 weeks
primitive alveoli (saccules) and type II cells present; surfactant detectable; survival possible with artifical ventilation
From a respiratory standpoint, at what fetal age is it viable
24 weeks
Fetal lung 28-30 weeks
capillary network surrounds saccules; unsupported survival
Fetal lung 36-40 weeks
true alveoli present, roughly 20 million at birth
Birth - 3 months
Pa02 rises as R to L mechanical shunts close
Birth - 6 yrs
rapid increase in alveoli and have 350 million by age 6
Fetus makes respiratory movments in utero called _____ ______ in utero
guppy breathing
Guppy breathing isFrom 30 weeks gestation, present 30% of the time at a rate of _____ breaths/min and responds to ______ ______
60 breaths/min / Chemical stimuli
Guppy breathing serves as ______ _______ to ensure that respiratory system is developed and ready at birth
prenatal practice
Proven in fetal lambs that denervation of the diaphragm leads to lung _______
hypoplasia
Traditional view of adapation of breathing
hypoxemia, hypercarbia and acidosis of birth asphyxia stimulates chemoreceptors that produce gasping followed by rhythmic breathing
Fetal lamb studies have shown that total devervation of carotid, aortic and peripheral chemoreceptors does not alter fetal breathing or initiation of _______ at birth
ventilation
Looks at normal blood gas values in smith anesthesia
page 27
Current view of adaptation of breathing- rhythmic breathing occurs with clamping of the umbilical cord and increasing 02 tensions from ___ _____
air breathing
Respiratory system transition – The primary event of the respiratory system transition is _____ ____ _____
initiation of ventilation
Initiation of ventilation changes the alveoli from a fluid-filled to an ___ _____ state
air-filled
Large surface tension forces are overcome by the small radius of the curvature of the diaphragm. Infant must generate a high negative presesure of ____ to inflate the lungs
(-70 cmH20)
Respiratory System Transition - With the onset of ventilation, pulmonary vascular resistance decreases dramatically and the pulmonary blood flow increases allowing ___ ______ to occur
gas exchange
Respiratory System Transition - Changes in P02, PC02, and pH are responsible for the decreases in ______
PVR
Respiratory System Transition - Increase in P02, decrease in C02 and decrease in ______
PVR
With nenonates, ______ is your best friend
PEEP
FRC of approximately __ to ___ ml/kg is established to act as a buffer against cyclical alterations in P02 and PC02 between breaths
25-30 ml/kg
Neonate and infant lungs prone to collapse due to
weak elastic recoil, weak intercostal muscles, intrathoracic airways collapse during exhalation
High closing volume encroaches upon FRC - small airway closure begins at volumes at or above _____ leading to lung collapse and ___ _____
FRC / VQ mismatch
Why don’t infants have lung collapse all of the time? Infants terminate the expiratory phase of breathing before reaching true ____ which results in ______ _______ and higher FRC. When anesthetized however, this protective mechanism is ________. The opposing tonic state of the intercostal muscles is overridden and atelectasis occurs. The moral of this story – PEEP of 5 cmH20 can help maintain FRC/lung inflation in the neonate during anesthesia.
FRC / intrinsic PEEP / abolished
The very first attempt to compensate is ________ and is usually the first sign of ______ ______
tachypnea / respiratory distress
Respiratory control is poorly developed in neonates. The system is normal by __ to ___ weeks of age, but likely remains immature for some time, especially in pre-term babies
3 to 4 weeks
________ control is present at birth so can respond to hypercarbia
chemoreceptor
If under 60 days of gestational age, will stay ________
overnight
Newborns respond to hypercarbia by increasing _________, but the slope of the response curve is decreased
ventilation
Hypoxia depresses the neonate’s response to _____
C02
Response to hypoxia is _______ - initial hypernea followed by depression of respiration in about ____ min
biphasic / 2 min
Initial hyperpneic response is abolished by ______ and low levels of _____ ______
hypothermia and anesthetic gases
______ is a common response and real danger, especially in pre-term infants
apnea
By 3 weeks, hypoxia produces sustained ________
hyperventilation
Apnea of infancy are respiratory pauses exceeding _____ sec or those accompanied by _______ or ______
20 sec / bradycardia / cyanosis
Hypoxia causes profound _______ in babies
BRADYCARDIA
Ventilate the baby. The number one reason you get into trouble with kids is not _______ for them
breathing
Contributing factors for apnea of infancy
increased work of breathing = FATIGUE
Apnea of infancy factors - Very _______ upper airway structures and ribcage which tend to collapse during inspiration, inefficient diaphragmatic _______, and 25% of muscles fibers in diaphragm are Type I fatigue-resistant work horse fibers whereas it’s _____% in adults
compliant / contraction / 55%
Apnea of infancy factors - Increased 02 consumption at ___ ml/kg, decreased FRC, and _______ closing volume
6 ml/kg | increased
Once hypoxia ensues, these factors will result in abnormal breathing patterns and ______ much more quickly than in the older child or adult
apnea
How do fetal needs differ from those of the newborn
gas exchange occurs in the placenta AND lungs required only nutrient flow of 5-10% of cardiac output
Fetal intracardiac and extracardiac shunts exist to minimized blood flow to the _____ while maximizing flow/02 delivery to _______ _____
lungs / organ systems
Ducuts Venosus, foramen ovale, ducuts arteriosus
look into these further
PVR drops at _____
birth
Fetal Circulation - _________ blood travels the descending aorta to the umbilical arteries to the placenta (very low resistance to flow). Oxygenated blood returns via the _______ ________ (P02 35 mmHg). Ducuts venosus diverts approx 50% of blood away from the ________ into the _______ then to the ______.
deoxygenated / umbilical veins / liver / IVC / RA
Fetal circulation - Preferential streaming causes 02 rich blood to be directed across the _____ _____ which connects the right and left ________. 02 rich blood fed to the ______and ejected into the aorta, thereby feeding the coronary and cerebral circulations.
foramen ovale / atrium / LV
Fetal Circulation - SVC and hepatic flow delivered to the _____. Pulmonary vasuclar resistance is _______. RV output is delivered across the ______ ________ which connects the _____ to the descending aorta. Blood entering the descending aorta returns to the _________ and feeds the lower body (P02 22mmHg)
RV / HIGH / ductus arteriosus / PA / placenta
Watch Dr. Najeeb
slide 31
Transitional circulation
umbilical cord is cut: increased SVR, reversal of shunts, onset of breathing decreases PVR and you have reversal of shunts
At birth, placental vessels are clamped and _______ increases dramatically
SVR
Initiation of ventilation increases ________ and _______ P02 which _______ pulmonary vasculature – this results in _____ decreases dramatically and pulmonary blood flow increases by ______%
arterial and alveolar / dilates / PVR / 450%
Transitional circulation - LA pressure increases and ____ pressure decreases. The _____ _______ will close (25-30% of adults have PFO)
RA / Foramen ovale
Transitional circulation - ductus arteriosus constricts within several minutes due to increased ____ and decreased circulating _________. Physiologic closure in ____ to _____ hrs and anatomic closures in 2-3 weeks.
P02 / prostaglandins / 10-15 hrs
Ductus venosus closes and becomes ______ over time
fibrous
The ______ ______, _____ _____ and _____ ______ are the shunts needed for effective fetal circulation that must close after birth to allow effect newborn circulation.
foramen ovale / ductus arteriosus / ductus venosus
At birth increased SVR and decreased PVR causes flow through the FO and DA to become ___ to ____, shunts _____ and circulation becomes more like that of an adult
left to right / close
In utero - PVR is ____ and SVR is _____
high / low
Born - SVR is _____ and PVR is _______ and shunts _____
high / low / close
Persistant Pulmonary Hypertension of the Newborn (PPHN) is persistance of fetal shunting beyond the normal transition period in the absence of structural ____ _____
heart defect
Because shunts are not anatomically closed immediately after birth, certain clinical conditions may contribute to either the persistance of OR a return to _____ _____
fetal circulation
Etiology of PPHN
hypoxia and acidosis
Consequences of PPHN
increased PVR, pulm HTN, decreased PBF, RAP > LAP, increased ductal flow
Can the consequnces of PPHN open the foramen ovale?
YES
Signs and symptoms of PPHN
marked cyanosis, tachypnea, acidosis, right to left shunt across FO and DA = marked cyanosis
Right to left shunt =
cyanotic shunt
PPHN - before anatomic closure of the fetal shunts, transient right to left shunting may occur in normal neonates during coughing, bucking, or straining during anesthetic __________ or __________
induction or emergence
PPHN treatment
hyperventilation (maintain alkalosis), Pulmonary vasodilators (prostaglandin), minimal handling, avoidance of stress
What is key with PPHN treatment
adequate ventilation and oxygenation
With PPHN you do not want them to get ____ or ____
cold or acidosis
Amniotic fluid is important for normal development of the ___ ______ and acts as a shock absorber for the fetus
fetal lung
The fetal kidney has ____ renal blood flow and _____ GFR
low / low
The fetal kidney has low renal blood flow and low GFR due to structurally immature - small sized ______, low systemic ______ _____, high renal ______ ______ and low permability of ________ capillaries
glomeruli / arterial pressure / vascular resistance / glomerular
Transitional changes to the renal system in the newborn - Systemic arterial pressure ______, renal vascular resistance _______ and increase in size and function occur through _______
increases / decreases / maturity
Renal system - Renal function at the time of birth and in the first few weeks of life depends upon ____ _______ age as well as the extent of transition. By _____ weeks all nephrons are developed, so premature babies have incomplete renal development.
post conceptual / 34 weeks
In a pre-term baby we talk about ____ ______ age
post conceptual
In the first several days of life in the full term infant there is a diminished ability to concentrate _______ resulting from the low _____ at birth. This is partially due to inadequte _______
urine / GFR / sodium
Urine osmolality at birth
700-800 mOsm/L
Urine creatinine at birth
0.8-1.2 g/dL
Inadequate sodium conservation - Neonates have a normal renin-angiotensin-aldosterone system and _________ fascilitates reabsorption of NA in the distal tubule. Immature neonatal tubules do not completely reabsorb ____ under the stimulus of aldosterone
aldosterone / NA
The neonate will excrete ______ even in the presence of a severe ____ deficit
Na / Na
The neonate is considered an _______ _____ _____
obligate sodium loser
Neonates can conserve filtered Na the first week at ___% and 2nd week ____%
70% / 84%
Urine Na neonate
20-25 mEq/L
The renin-angiotensin-aldosterone system is the primary ________ mechanism for the reabsorption of the Na and H20 losses of plasma, blood, GI tract fluid and third space fluid during ______
compensatory / surgery
IV fluid must contain ______. Why? Neonates cannot completely conserve Na, so a baby will continue to produce dilute urine to the point of dehydration without adequate fluid replacement.
Na
All neonates they will run a background infusion of ____
D5
Increased renal blood flow and decreased Renal vascular resistance result in rapid improvement in renal function within the first ___ to ___ days of life. This is reflected in the increased ability of the infant to _____ ____ with time.
3 to 4 / concentrate urine
Glucose needs of the neonate is addressed by having maintenance fluid of _______
D5 .2NS
In the face of ongoing surgical blood loss, neonates and infants will require red cell replacement _______
sooner
Higher Hgb/Hct because of high 02 demand with limited ability to increase ____ _____
cardiac output
lowest acceptable Hct
35%
_______ blood volume per unit weight
increased
_______ cardiac output per unit weight
increased
term baby blood volume
90 ml/kg
pre-term baby blood volume
100 ml/kg
Are infants homeotherms?
yes
ability of infants to thermoregulate is significantly _____ and easily ______
limited / overwhelmed
Homeostasis is accomplished by balancing
heat production with heat loss
The neonate’s limited thermal range is a function of their (what 3 things)
small size, increased surface area to volume ration, increased thermal conductance
Heat loss occurs in two stages: Transfer of heat from body core to ____ ______ AND dissipation of heat from the skin surface to the ______
skin surface / environment
Both stages of heat loss are governed by the laws of _____, ______, ______ and ______
conduction, convection, radiation, evaporation
Temperature in the OR should be
80 degrees
Factors that control conductive loss in infants are _______ ______ flow and ________ - the amount of subcutaneous tissue.
cutaneous blood / insulation
Prevention of conductive losses
warm blankets, heating mattress, and bair hugger
Factors that control convetion losses (3)
air temp, air velocity, volume of air flow
Prevention of convection losses
keep OR at 80 degrees and reduce air movment across body surface
Factors that control radiation heat losses
temperature gradient b/t skoin and surrounding surfaces and total radiating surface of the infant
Prevention of readiation losses
keep OR warm, radiant lamps (french fry lights)
Factors that control evaporation losses from skin and respiratory system
relative humidity and minute ventilation
Prevention of evaporation losses
cover exposed body cavities, heat and humidify inspired gases
Heat production is achieved by
voluntary muscles activity, involuntary muscle activity and NON-SHIVERING THERMOGENESIS
Major component of thermal regulation in the neonate
non-shivering thermogenesis
Non- shivering thermogenesis is achieved by metabolism of _____ ______. This develops in the fetus between ___ and ____ weeks gestation and comprises 2-6% of the neonat’s total body weight.
brown fat / 26-30 weeks
Brown fat is located in the _______, b/t the scapulae, around the adrenals and in the ________
mediastinum /axilla
Brown fat has an ________ vascular supply and rich innervation of the ______
abundant / SNS
Non-shivering thermogenesis occurs with ____ ____, is mediated by the ______, and the heat produced is a product of ____ _____ metabolism
cold stress / SNS / fatty acid
