Lecture 1-Pediatric Anesthesia 2020 Flashcards
Transition = the change from fetal to ___ life
Extrauterine
Pre-term = prior to ___ weeks gestational age
37
Neonate = ___-___ days of life
1-28
Infant = ___ days to ___ year
29 days to 1 year
Child > ___ year
> 1 year
Most significant part of transition occurs within the first ___-___ hours after birth
24-72 hours
Adaptive changes of the newborn—establish ___; convert ___; recover from birth ___; maintain core ___
Establish FRC; convert circulation; recover from birth asphyxia; maintain core temperature
Fetal respiration—gas exchange occurs in the ___
Placenta
Fetal Hgb shifts oxyhemoglobin dissociation curve to the ___ (right/left)—___ (increased/decreased) O2 loading in the lungs/placenta, ___ (increased/decreased) O2 unloading at tissues
Left—increased O2 loading in the lungs/placenta, decreased O2 unloading at tissues
Hgb for full term neonate = ___-___ g/dL
18-20 g/dL
Fetal lung development—___-___ weeks—capillary network surrounds saccules; unsupported survival is possible (will probably still need CPAP or positive pressure ventilation)
28-30 weeks
Fetal lung development—___-___ weeks—true alveoli present, roughly 20 million at birth
36-40 weeks
Fetal lung development—___-___ months—PaO2 rises as R to L mechanical shunts close
Birth-3 months
Fetal lung development—up to __ years—rapid increase in alveoli—350 million at this age
6 years
Fetus makes respiratory movements in utero, aka “___ breathing in utero”
Guppy
Fetal respiratory movements serve as prenatal practice to ensure that respiratory system is developed and ready at birth—T/F?
True
Adaptation of breathing—traditional view—___emia, ___carbia, ___osis of birth asphyxia stimulate ___ that produce ___ followed by rhythmic breathing
Hypoxemia, hypercarbia, acidosis of birth asphyxia stimulate chemoreceptors that produce gasping followed by rhythmic breathing
With the onset of ventilation, pulmonary vascular resistance ___ (increases/decreases) dramatically, and the pulmonary blood flow ___ (increases/decreases) allowing gas exchange to occur
PVR decreases dramatically, and the pulmonary blood flow increases
Changes in PO2, PCO2, and pH are responsible for the decrease in PVR—___ (increase/decrease) in PO2, ___ (increase/decrease) in CO2
Increase in PO2, decrease in CO2
Adaptation of breathing—current view—rhythmic breathing occurs with ___ of the umbilical cord and ___ (increasing/decreasing) O2 tension from air breathing
Rhythmic breathing occurs with clamping of the umbilical cord and increasing O2 tension from air breathing
The primary event of the respiratory system transition is initiation of ___
Ventilation
Initiation of ventilation changes the alveoli from a ___-filled to an ___-filled state
Fluid-filled to an air-filled state
Infants must generate high negative pressure, -___ cm H2O, to inflate the lungs—___ initiates this high negative pressure
-70 cm H2O—crying initiates this high negative pressure
FRC of approximately ___-___ ml/kg is established to act as a buffer against cyclical alterations in PO2 and PCO2 between breaths
25-30 ml/kg
Neonate and infant lungs are prone to collapse—weak elastic recoil, weak intercostal muscles, and intrathoracic airways collapse during exhalation—T/F?
True
Small airway closure begins at volumes at or above FRC, leading to lung collapse and V/Q mismatch—T/F?
True
Why don’t infants have lung collapse all of the time?—infants terminate the expiratory phase of breathing before reaching their true ___, which results in intrinsic ___ and a ___ (higher/lower) FRC
Before reaching their true FRC, which results in intrinsic PEEP and a higher FRC
When infants are anesthetized, their protective mechanism of terminating the expiratory phase of breathing before reaching their true FRC is abolished, causing atelectasis to occur—T/F?
True
___ can help maintain FRC/lung inflation in the neonate during anesthesia
PEEP of 5 cm H2O
As kid is going to sleep and protective respiratory mechanisms are abolished, turn APL valve to about ___ to maintain PEEP
5
Respiratory control is well developed in neonates—T/F?
False—even though their respiratory systems are normal by 3-4 weeks of age, the system likely remains immature for sometime, especially in pre-term babies
Chemoreceptor control ___ (is/is not) present at birth
Is present at birth—can respond to hypercarbia
Newborns respond to hypercarbia by ___ (increasing/decreasing) ventilation; the slope of the response curve is ___ (increased/decreased)
Increasing ventilation; the slope of the response curve is decreased
___ia depresses the neonate’s response to CO2
Hypoxia
Neonate’s response to hypoxia is biphasic—initial ___nea followed by ___ of respiration in about 2 min.
Initial hyperpnea followed by depression of respiration in about 2 min.
The initial hyperpneic response to hypoxia in neonates is abolished by ___thermia and ___ (low/high) levels of anesthetic gases
Hypothermia and low levels of anesthetic gases
___ is a common response and a real danger, especially in pre-term infants
Apnea
By ___ weeks of age, hypoxia produces sustained hyperventilation
3
Apnea of infancy = respiratory pauses exceeding ___ seconds or those accompanied by ___cardia or ___osis
Exceeding 20 seconds or those accompanied by bradycardia or cyanosis
Hypoxia causes profound ___cardia in babies
Bradycardia
HR 60 in a baby = ___, need to start ___
Hypoxia, need to start compressions
Increased work of breathing in infants leads to ___
Fatigue
Contributing factors for apnea of infancy—infants have very compliant upper airway structures and ribcage that tend to collapse during inspiration—T/F?
True
Contributing factors for apnea of infancy—infants have inefficient ___ contraction; ___% of muscle fibers in the infant’s diaphragm are type I fatigue-resistant (in adults, 55% are this type)
Inefficient diaphragmatic contraction; 25% of muscle fibers in the infant’s diaphragm are type I fatigue-resistant
Contributing factors for apnea of infancy—___ (increased/decreased) O2 consumption—___ml/kg; ___ (increased/decreased) FRC; ___ (increased/decreased) closing volume; once hypoxia ensues, these factors will result in abnormal breathing patterns and apnea much more quickly than in the older child or adult
Increased O2 consumption—6 ml/kg; decreased FRC; increased closing volume
CV in the fetus—gas exchange occurs in the ___
Placenta
CV in the fetus—lungs require only ___-___% of cardiac output
5-10%
Fetal intracardiac and extracardiac shunts exist to minimize blood flow to the ___ while maximizing flow/O2 delivery to ___ systems
Minimize blood flow to the lungs while maximizing flow/O2 delivery to organ systems
(3) fetal shunts:
- Ductus venosus
- Foramen ovale
- Ductus arteriosus
Fetal circulation (parallel)—deoxygenated blood travels to the ___ aorta to the ___ arteries to the ___ (very ___ (high/low) resistance to flow)
Deoxygenated blood travels to the descending aorta to the umbilical arteries to the placenta (very low resistance to flow)
Fetal circulation (parallel)—blood becomes oxygenated in the ___
Placenta
Fetal circulation (parallel)—oxygenated blood returns to the fetus via the ___ vein (PO2 ___ mm Hg)
Oxygenated blood returns to the fetus via the umbilical vein (PO2 35 mm Hg)
Fetal circulation (parallel)—ductus ___ diverts approximately ___% of oxygenated blood away from the fetal ___ (bypassing ___ circulation) into the ___ vena cava then to the ___ atrium
Ductus venosus diverts approximately 50% of oxygenated blood away from the fetal liver (bypassing hepatic circulation) into the inferior vena cava then to the right atrium
Fetal circulation (parallel)—oxygenated blood passes through the ___ into the ___ atrium, to the ___ ventricle, and is ejected out from the ___, feeding the coronary and cerebral circulations
Oxygenated blood passes through the foramen ovale into the left atrium, to the left ventricle, and is ejected out from the aorta, feeding the coronary and cerebral circulations
Fetal circulation—deoxygenated blood from the fetus’ body is delivered into the ___, through the ___ atrium, to the ___ ventricle, to the main ___ artery
Deoxygenated blood from the fetus’ body is delivered into the SVC, through the right atrium, to the right ventricle, to the main pulmonary artery
Fetal circulation (parallel)—pulmonary vascular resistance is ___ (low/high), so right ventricular output bypasses the ___ through the ___, which connects the ___ artery to the ___ aorta
PVR is high, so right ventricular output bypasses the lungs through the ductus arteriosus, which connects the pulmonary artery to the descending aorta
Fetal circulation (parallel)—deoxygenated blood from the descending aorta feeds the ___ body of the fetus (PO2 ___ mm Hg)
Lower body of the fetus (PO2 22 mm Hg)
Fetal circulation (parallel)—deoxygenated blood leaves the fetus through the ___ arteries to get back to the ___ to pick up oxygen
Leaves the fetus through the umbilical arteries to get back to the placenta to pick up oxygen
Transitional circulation (series)—at birth, placental vessels are clamped—SVR ___ (increases/decreases) dramatically, causing ___ of shunts
SVR increases dramatically, causing reversal of shunts
Transitional circulation (series)—initiation of ventilation ___ (increases/decreases) arterial and alveolar PO2, which ___ (constricts/dilates) pulmonary vasculature—PVR ___ (increases/decreases) dramatically, pulmonary blood flow ___ (increases/decreases) 450%, ___ of shunts
Initiation of ventilation increases arterial and alveolar PO2, which dilates pulmonary vasculature—PVR decreases dramatically, pulmonary blood flow increases 450%, reversal of shunts
Transitional circulation (series)—LA pressure ___ (increases/decreases), RA pressure ___ (increases/decreases)
LA pressure increases, RA pressure decreases
Transitional circulation (series)—foramen ovale closes ___
Immediately
Transitional circulation (series)—ductus arteriosus constricts within several minutes due to ___ (increased/decreased) PO2 and ___ (increased/decreased) circulating prostaglandins (PGI2, PGE1); physiologic closure occurs in ___-___ hours, anatomic closure occurs in ___-___ weeks
Ductus arteriosus constricts within several minutes due to increased PO2 and decreased circulating prostaglandins; physiologic closure occurs in 10-15 hours, anatomic closure occurs in 2-3 weeks
Transitional circulation (series)—ductus venosus becomes ___ over time; no specific time frame for closure
Fibrous
The foramen ovale, ductus arteriosus, and ductus venosus are the shunts needed for effective fetal circulation that must close after birth to allow effective newborn circulation—T/F?
True
___ (increased/decreased) SVR, ___ (increased/decreased) PVR allow for closure of fetal shunts; flow through FO and DA becomes ___ to ___, shunts close, and circulation becomes like that of an adult
Increased SVR, decreased PVR allow for closure of fetal shunts; flow through FO and DA becomes left to right, shunts close, and circulation becomes like that of an adult
Circulation in utero—PVR ___ (high/low), SVR ___ (high/low)
PVR high, SVR low
Extrauterine circulation—SVR ___ (high/low), PVR ___ (high/low); shunts physiologically close
SVR high, PVR low
Pulmonary blood flow in fetus—___-___%
5-10% of CO (remember, goal in utero is to minimize blood flow to the lungs and maximize flow/O2 delivery to organ systems)
Pulmonary blood flow in neonate—___%
100%
PPHN =
Persistent pulmonary hypertension of newborn
What does this describe?—persistence of fetal shunting beyond the normal transition period in the absence of a structural heart defect
PPHN
Etiology of PPHN = ___ia and ___osis
Hypoxia and acidosis
Consequences of PPHN—___ (increased/decreased) PVR; pulmonary ___tension; ___ (increased/decreased) pulmonary blood flow; ___ atrial pressure > ___ atrial pressure; ___ (increased/decreased) ductal flow; this can reopen the ___
Increased PVR; pulmonary hypertension; decreased pulmonary blood flow; right atrial pressure > left atrial pressure; increased ductal flow; this can reopen the foramen ovale
Signs and symptoms of PPHN—marked ___; ___pnea; ___osis; ___ to ___ shunt across foramen ovale and ductus arteriosus = marked ___
Marked cyanosis; tachypnea; acidosis; right to left shunt across foramen ovale and ductus arteriosus = marked cyanosis
Before anatomic closure of the fetal shunts, transient right to left shunting may occur in normal neonates during coughing, bucking, or straining during anesthetic induction or emergence—T/F?
True
Treatment of PPHN—___ventilation to maintain ___osis; pulmonary vaso___ (i.e.: prostaglandin); minimal handling; avoidance of ___
Hyperventilation to maintain alkalosis; pulmonary vasodilators (i.e.: prostaglandin); minimal handling; avoidance of stress
Treatment of PPHN—adequate ___ and ___ is key!
Adequate ventilation and oxygenation is key!
Renal system—major function in fetus is passive production of urine, which contributes to the formation of ___ fluid
Amniotic fluid
Amniotic fluid is important for normal development of the fetal ___ and acts as a ___ absorber for the fetus
Important for normal development of the fetal lung and acts as a shock absorber for the fetus
Characteristics of the fetal kidney—___ (high/low) renal blood flow; ___ (high/low) glomerular filtration rate
Low renal blood flow; low glomerular filtration rate
Why does the fetus have low RBF and GFR?—kidneys are structurally immature with small size and number of glomeruli; ___ (high/low) systemic arterial pressure; ___ (high/low) renal vascular resistance; ___ (high/low) permeability of glomerular capillaries
Low systemic arterial pressure; high renal vascular resistance; low permeability of glomerular capillaries
Transitional changes in the newborn (renal)—systemic arterial pressure ___ (increases/decreases); renal vascular resistance ___ (increases/decreases); ___ (increase/decrease) in size and function of kidney occurs through maturity
Systemic arterial pressure increases; renal vascular resistance decreases; increase in size and function of kidney occurs through maturity
By ___ weeks, all nephrons are developed, so a premature baby has incomplete renal development
34 weeks
In the first several days of life in the full term infant, there is diminished ability to ___ urine, resulting from the low GFR at birth; urine osmolarity is ___-___ mOsm/L; creatinine is ___-___ mg/dL
Concentrate; urine osmolarity is 700-800 mOsm/L; creatinine is 0.8-1.2 mg/dL
Full term infants’ inability to concentrate urine in the first several days of life is d/t inadequate ___ conservation
Sodium
Neonates have a normal RAAS that facilitates reabsorption of sodium in the distal tubule; however, immature neonatal tubules do not completely reabsorb sodium under the stimulus of aldosterone—T/F?
True
Neonates will continue to excrete sodium, even in the presence of a severe sodium deficit d/t immaturity of their renal tubules—T/F?
True
The neonate is considered an “obligate ___”
“Obligate sodium loser”
Neonates can conserve filtered sodium—1st week = ___%; 2nd week = ___%; adults ___%
1st week = 70%; 2nd week = 84%; adult = 99.5%
Adult urine sodium = ___-___ meq/L
5-10
Neonate urine sodium = ___-___ meq/L
20-25 meq/L
Since neonates cannot completely conserve sodium, a baby will continue to produce dilute urine to the point of ___ without adequate fluid replacement; IVF must contain ___ to prevent this
To the point of dehydration; IVF must contain sodium to prevent this
___ (increased/decreased) renal blood flow and ___ (increased/decreased) renal vascular resistance result in rapid improvement in renal function within the first 3-4 days of life; this is reflected in the increased ability of the infant to ___ urine with time
Increased renal blood flow and decreased renal vascular resistance result in rapid improvement in renal function within the first 3-4 days of life; this is reflected in the increased ability of the infant to concentrate urine with time
IV fluid replacement given to the neonate must contain ___; most facilities utilize ___ or ___
Must contain sodium; most facilities utilize NS or LR
Maintenance fluid in the neonate—___ needs of the neonate must also be addressed
Glucose needs
Maintenance fluid for neonates should contain ___
Glucose
Balanced maintenance fluid in a baby = ___
D5.2NS
In the face of ongoing surgical blood loss, neonates and infants will require red cell replacement sooner than later—T/F?
True
Higher Hgb/Hct is required in neonates/infants because of ___ (high/low) oxygen demand with limited ability to increase cardiac ___; Hct ___% is the lowest acceptable
High oxygen demand with limited ability to increase cardiac output; Hct 35% is the lowest acceptable
Neonates/infants have ___ (increased/decreased) blood volume per unit weight
Increased
Neonates/infants have ___ (increased/decreased) cardiac output per unit weight
Increased
___ ml/kg blood volume in term baby
90 ml/kg
___ ml/kg blood volume in pre-term baby
100 ml/kg
Ability of infants to thermoregulate is significantly limited and easily overwhelmed—T/F?
True
The neonate’s limited thermal range is a function of their ___ size; ___ (increased/decreased) surface area to volume ratio; ___ (increased/decreased) thermal conductance
Small size; increased surface area to volume ratio; increased thermal conductance
Heat loss occurs in two stages in neonates/infants—transfer of heat from body ___ to skin ___ (internal temperature gradient); dissipation of heat from the skin surface to the ___ (external heat gradient)
Transfer of heat from body core to skin surface (internal temperature gradient); dissipation of heat from the skin surface to the environment (external heat gradient)
Heat loss is governed by what (4) methods:
- Radiation
- Convection
- Conduction
- Evaporation
What heat loss method is this describing?—electromagnetic energy from the body to colder objects in the room (requires no direct contact, heat emitted from an object or body); highest percentage of heat loss
Radiation
What heat loss method is this describing?—heat loss from surface to air currents
Convection
What heat loss method is this describing?—surface to surface heat loss
Conduction
What heat loss method is this describing?—heat loss via vaporization
Evaporation
Heat production is achieved by ___ and ___ muscle activity; ___ thermogenesis—major component in the neonate
Voluntary and involuntary muscle activity; non-shivering thermogenesis—major component in the neonate
Non-shivering thermogenesis = metabolism of ___
Brown fat
Non-shivering thermogenesis develops in the fetus between ___-___ weeks gestation; comprises ___-___% of the neonate’s total body weight; located in the ___stinum, between the ___, around the ___, in the ___
26-30 weeks gestation; comprises 2-6% of the neonate’s total body weight; located in the mediastinum, between the scapulae, around the adrenals, in the axilla
Brown fat in the neonate has an abundant ___ supply and rich innervation from the ___ nervous system
Has an abundant vascular supply and rich innervation from the sympathetic nervous system
Non-shivering thermogenesis occurs with ___ stress; is mediated by the ___ nervous system; ___ is produced as a product of fatty acid metabolism
Occurs with cold stress; is mediated by the sympathetic nervous system; heat is produced as a product of fatty acid metabolism
Consequences of non-shivering thermogenesis = ___ (increased/decreased) O2 consumption»_space; ___ia»_space; ___osis;
___ (increased/decreased) glucose utilization»_space; release of ___ acid»_space; ___glycemia
___ (increased/decreased) surfactant production»_space; ___ of alveoli»_space; ___ of fetal circulation (foramen ovale and ductus arteriosus)
Increased O2 consumption»_space; hypoxia»_space; acidosis
Increased glucose utilization»_space; release of lactic acid»_space; hypoglycemia
Decreased surfactant production»_space; collapse of alveoli»_space; reopening of fetal circulation (foramen ovale and ductus arteriosus)
