Peds Week 1 Flashcards
Neonate is defined as:
0-30 days old
Infants are defined as:
1 month- 1 year
Children are defined as:
older than 1 year
A fetus is considered “viable” outside the mother at how many weeks?
24 weeks gestation
Alveolar formation begins at ___-___ weeks gestation.
32-36 weeks
Surfactant production begins at ___ weeks gestation.
27 weeks.
Surfactant is produced by____?
Type II pneumocytes.
The absence contributes to RDS in premies.
For a preterm delivery, the mother is given betamethasone or dexamethasone 48 hours prior to delivery. Why?
- Accelerates lung maturation in the premie
- Stimulates surfactant production
- Decreases mortality after 30 weeks gestation
The first breath of an infant needs a pressure of 40-80 cm H2O. why?
(normal is ~20 cm H2O)
-To overcome surface tension forces
-To introduce air into fluid filled lungs
(adequate surfactant is needed to achieve this)
The lecithin/sphingomeylin (L/S) ratio in amniotic fluid correlates with what?
Lung maturity
Surfactant synthesis is increased by:
- Glucocorticoids
- thyroxine
- Heroin
- cAMP
Surfactant is inactivated by:
- Alveolar-capillary leak
- Pulmonary edema
- Hemhrrhage (hemoglobin)
- Alveolar cell injury
- Meconium
Synthetic surfactant is used to treat:
- Premies with surfactant deficiency
- Pulmonary HTN
- Congenital diaphragmatic hernia (one lung collapsed)
- Meconium aspiration syndrome
- ARDS (Adults and Children)
Lung development continues until a child is about ___ years old.
10 years old
- The number and size of alveoli increases until age 8
- Developmet of alveoli from saccules is completed by age 18 months
Neonatal lung compliance and chest wall compliance are high. Why?
- cartilaginous ribs
- limited thoracic muscle mass
- more prone to atelectasis
Diaphragm is most important muscle of breathing in infants
Infants are obligate nose breathers until:
5 months
The larynx is located:
Cephalad C3-C4
Adults=C5-C6
____ is the narrowest part of the airway in children.
Cricoid Cartilage
Adults = vocal cords
Compared to adults, the pediatric epiglottis is:
Long and U shaped and often stiffer than the adult epiglottis and more difficult to displace.
T/F In neonates, hypoxia depresses ventilation via suppression of medullary centers.
True.
Macroglossia
Large Tongue
Trisomy 21 (Down’s) and many more
Airway Retrognathia (micrognathia)
Small jaw/mouth; retrognathia =posterior mandible or “overbite”
Bohr effect:
Explains how hydrogen ions and carbon dioxide affect the affinity of oxygen in Hemoglobin. If pH was lower than it normally was (normal physiological pH is 7.4), then the hemoglobin does not bind oxygen as well.
Apnea in infants =
pause in ventilation lasting > 20 seconds that is accompanied by bradycardia and cyanosis.
Periodic breathing =
Apneic spells <10 seconds, no bradycardia or cyanosis.
Periodic breathing is a NORMAL phenonmenon.
100% of premies
80% of term neonates
30% of infants age 10-12 months.
-Can be abolished by adding 3% CO2 to inspired gas.
Central Apnea =
No initiation of breath. Most common in premature.
Obstructive Apnea =
breaths initiated, but no passage of gas due to obstruction in airway
Apnea of Prematurity is exacerbated by:
- Anesthetic gases
- Narcotics
- Hypo: thermia, glycemia, anemia
- Hyper: thermia, glycemia
Apnea of Prematurity is diminished (not eliminated) by:
- Caffeine 10mg/kg IV
- Theophylline (not used often)
- Stimulation
- Avoidance of general anesthesia
- Avoidance of narcotics
Why do infants desaturate so rapidly?
- Decreased FRC (less than adults)
- Greater VO2 consumption
- Shunts
- Anesthetic technique
- Patient cooperation
Key Concept FRC is the available reservoir of O2 during apnea (already have decreased FRC). VO2 reflects the rate that reservoir is depleted
Factors that contribute to increased right atrial pressure, therefore causing R to L shunting if patent foramen ovale.
- Hypoxia
- Hypercarbia
- High airway pressures
- Hypothermia
- Pain
How long does the Foramen Ovale stay patent?
- A patent Foramen Ovale (PFO) is NORMAL in neonates. PFO persists for months.
- at 1 year, 50% of infants will have a probe patent FO.
- 25% of adults have a probe patent FO.
ANS in adults: Sympathetic dominant
ANS in infants: Parasympathetic dominant
What does this mean for infants vs adults?
- Laryngoscopy in adults: tachycardia/HTN; infants: bradycardia/decreased CO.
- Hypoxia in adults: +/- Tachycardia; infants: Bradycardia
- Adult high spinal: Hypotension; Infant: no hypotension.
Key Concept Protect the heart rate of infants and children. Their CO is HR driven.
Hypoglycemia in a neonate=
<30mg/dl
Hypoglycemia in an infant =
<40mg/dl
When does the Ductus close? how?
- About 12-15 hours after birth from muscular contraction.
- As SVR rises (umbilical cord clamped/cut), and PVR decreases (breathing, increased pO2), the shunt reverses. Blood flows from L to R and closes the ductus.
- Persistent Fetal Circulation (PFC) is a structural heart disease. Critical medical/surgical illness. Hypoxemia and or acidosis: reverse/prevents shunt closure
Fetal hemoglobin has a greater or lesser affinity for O2 than Adult hemoglobin?
Fetal hemoglobin has a GREATER affinity for oxygen.
Fetal HgB: p50 is 19
Adult HgB: p50 is 26
Packed Red Cells are replaced a dose of:
10ml/kg
FFP: 10ml/kg Platelets: 1 unit/10kg, raises platelets by 50k Cryoprecipitate 1 unit/10kg Crystaloids 3:1 Colloids 1:1
Why does a neonate require a higher minute ventilation?
-Increased oxygen consumption.
Neonate= 6ml/kg/min Adult = 3.5ml/kg/min
-Increased ventilation to FRC ratio.
Do neonates have a faster or slower inhalation induction compared to older children/adults?
Faster.
They have a decreased FRC (smaller volume) and increased alveolar ventilation. The anesthetic partial pressure can be achieved quicker due to the faster turnover of the FRC and increased alveolar ventilation
T/F: the intercostal muscles are the main muscles of inspiration for neonates and infants?
False: The diaphragm is the primary muscle of inspiration, the intercostals are underdeveloped and contribute very little to ventilation.
Describe Type 1 muscle fibers.
Does the neonate have more or less Type 1 muscle fibers at birth?
- Slow twitch fibers for endurance, resist fatigue
- Fewer Type 1 muscle fibers at birth (25% at birth and 55% in Adulthood. Preterm infants have ~10% slow twitch fibers. This explains the decrease in neonatal ventilatory reserve. Tachypnic infants will eventually fatigue and progress from resp distress to failure.
Describe Type 2 muscle fibers.
Does the neonate have more or less Type 2 than Type 1 fibers?
Fast twitch fibers for short bursts of heavy work, they tire easily.
Neonates have more Type 2 fast twitch fibers at birth than Type 1 slow twitch.
What age group of peds patients is most at risk for post-anesthesia apnea?
- Patients less than 60 weeks post conceptual age.
- They should be admitted for 24 hours following anesthesia for observation with an apnea monitor.
- the younger the patient = increased risk for post op apnea.
What is given prophylacticly for post op apnea?
Caffeine (10mg/Kg IV).
Theophylline can be used too. Neonate physiology converts it into caffeine. Theophylline is associated with greater risk of toxicity.
Lung volumes and capacities compared to adults
In the Adult, chest wall expands and the lungs tend to collapse. this creates negative pressure in the pleural space.
Compared to the adult, neonates have:
- Decreased lung compliance
2 Increased Chest wall compliance d/t cartilaginous rib cage and decreased structural support.
These conditions favor paradoxical breathing (chest wall collapse during inspiration.
Fetal Hemoglobin P50 =?
Fetal Hemoglobin P50= 19 mmHg
Left shift of the oxygen dissociation curve.
The lower PP of Oxygen is favorable to the fetus by creating a lower gradient across the placental membrane that facilitates passage of O2 from mother to fetus.
Hgb at birth = ___ g/dL
17 g/dL
Fetal hemaglobin (HgbF) has a greater affinity for oxygen because…..?
Adult hemoglobin (HgbA) consists of 2 Alpha and 2 Beta chains while HgbF has 2 Alpha and 2 Gamma chains. 2,3 DPG causes a R shift of the oxyhemoglobin curve. The binding site for 2,3 DPG is only on the Beta chain on HgbA. HgbF does not bind 2,3 DPG, therefore HgbF has an increased affinity for oxygen and the curve shifts L.
At what age is HgbF replaced by HgbA?
When does one expect to see physiologic anemia in an infant as HgbG is replaced by HgbA?
- by 4-6 months of age, HgbA has completely replaced HgbF and P50= 26.5 mmHg (adult physiology)
- At 2-3 months of age, infants experience physiologic anemia (Hgb 10g/dL) related to replacement of HgbF with HgbA. At 4 months, erythropoiesis increases and hemoglobin concentration begins to increase.
What is the relative transfusion trigger for pediatrics?
-For children with severe cardiopulmonary disease:
Hgb <13
-For children with moderate cardiopulmonary disease:
Hgb<10
Transfusion should be guided by ongoing blood loss, anticipated blood loss, baseline H&H as well as signs of inadequate oxygenation and end-organ dysfunction rather than on the sole basis of a trigger value.
What is the dose of RBC’s for pediatric transfusion?
10-15ml/Kg
10ml/kg wil raise the Hgb by 1-2g/dL
Renal maturation in the neonate vs the adult.
At birth, the neonate kidney is immature, in what ways is it different than the adult kidney?
Neonates have:
- Decreased perfusion pressure (remember their SBP is in the mid 60s with a MAP near their gestational age (40 weeks, etc)
- Decreased GFR (GFR reaches adult levels around 8-24 months)
- Decreased ability to dilute and concentrate urine.
Neonates have a poor ability to conserve water and poor ability to excrete large volumes of water. Therefore they cannot tolerate fluid restrictions or overloads. The neonate is an obligate sodium LOSER in the 1st few days of life, and tend to also lose glucose.
-Renal tubular function does not achieve adult function until about 2 yrs old.
What is the dose for Fresh Frozen Plasma for Peds?
Dose of FFP = 10-20ml/kg
FFP is not indicated for IV volume expansion
When is platelet transfusion indicated for pediatric patients?
indicated during invasive procedures to maintain platelets >50,000
What is the dose for platelet transfusion for Pediatric patients?
Dose if obtained from apheresis = 5ml/Kg
Dose if pooled platelet concentrate= 1 pack /10 kg of body wt.
WTF is apheresis vs pooled platelets?
Pooled random donor platelet concentrates are prepared from platelets that have been harvested by centrifuging units of whole blood. … Apheresis platelets are collected from a single donor and are equivalent to ~4-6 pooled units. An apheresis platelet concentrate contains 200-400mL of plasma.
What are common complications associated with transfusions in pediatric patients?
- Alkalosis from citrate metabolism to bicarbonate in the liver.
- Hypothermia from cold blood
- Hypocalcemia from citrate binding to Ca
-Hyperkalemia from admin of older blood.
Risk of hyperK is decreased by transfusing wased or fresh cells less than 7 days old.
Body water distribution:
T/F: Adults have a higher % ICF vs % of EFC. This is the opposite in premature and neonates.
TRUE!!
Premature and term neonates have a larger EFC than IFC. There is a diuresis after birth that reduces ECF volume.
For older children and adults, a higher IFC provides a volume reserve in times of intravascular volue loss: fever, fasting, diarrhea, etc and allows for fluid shifts that premies and neonates cannot do.
% Total body water for a premie and neonate=
85% for premie
75% for term neonate
-By age 1 year, children have the same values as adults
60% for child and adult
% EFC and % ICF for premie and neonate:
Premie: EFC= 60% and ICF = 25%
Neonate: EFC= 40% and ICF = 35%
Hence babies are considered “water bags”
-By age 1 year, children have the same values as adults
Older child and adult:
EFC= 20% and IFC = 40%
A glucose of ____ is considered hypoglycemic. What is the treatment for hypoglycemia?
Glucose <40 mg/dL
Tx: 10% glucose at 2ml/Kg IV.
If Seizures are present, 4ml/Kg IV.
After bolus, start gtt of D10 at 8mg/kg/min and titrate to a glucose >40mg/dL.
Routine use of maintenance fluids containing dextrose is not recommended. Only use dextrose if a child is premature, less than 48 hrs old, small for gestational age, newborn of diabetic mother, children with diabetes who receive insulin on day of surgery, children receiving glucose-based parental nutrition.
MAC is Highest as a neonate or infant?
Infant (1-6 months) MAC Highest (higher than adult)
Infant 2-3 months MAC Peaks
Neonate: 0-28 days MAC is lower than infant
Premature: MAC is lowest (lower than neonate)
MAC for SEVO:
0-6 months MAC is 3.2%
6mo-12 yrs old MAC is 2.5% (adult is 2-2.2)
Neonates are more or less sensitive to Succinylcholine?
Neonates have a normal sensitivity to succinylcholine (Scholine)
However, the combination of increased ECF, normal sensitivity to Scholine and the fact that all NMBs are water-soluble necessitates an increased dose of Scholine. 2mg/kg (adults= 1mg/kg)
Neonates are more or less sensitive to non-depolarizing NMBs?
MORE sensitive.
HOWEVER…
However, the combination of increased ECF, increased sensitivity to non-depolarizing NMBs and the fact that all NMBs are water-soluble assumes any dosing changes to be a wash. The duration of action may be prolonged due to immature metabolic/renal clearance.
What is the appropriate size for a cuffed oral ETT and correct depth of insertion from teeth to mid trachea for a healthy 1 yo patient weighing 10kg?
4.0 ETT at 12.5 cm at the teeth.
TUBE SIZE: (16 + age in years) / 4 (round to the nearest half size)
TUBE DEPTH: (age/2) + 12 from mid trachea to teeth
OR
For measurement from ETT cm mark at the lip:
10+age in years.
Tube depth and measurement to the lip/teeth will be different values (read question carefully when making calculation)
At birth, where does the spinal cord extend to?
L3 at birth
By age 1, the spinal cord takes the adult position around L1.
The development of a gas lead should occur between ____ and ____ cm H2O in a pediatric patient.
An air leak should be present between 20 and 25 cm H2O, if not, then the ETT should be changed to the next half size smaller.
LMA size for a 15kg patient:
2.O LMA
