Neonatal Emergencies Flashcards
The left shift on the oxyhemoglobin curve for neonates is primarily due to what factor?
- No 2,3 DPG
What is the oxygen consumption rate of the Neonate?
- 4-7 mL/kg/min
In periods of hypoventilation, what factor in the neonatal physiology leads to a decrease in blood oxygen levels?
- High rate of 02 consumption
Body composition of water of a fetus?
- 90%
Body composition of water of a preterm infant?
- 80%
Body composition of water of a full-term infant?
- 70%
Body composition of water of a 6-12 month old?
- 60%
Factors that have implications for drug dosing in infants?
- High relative body water composition
- Increased volume of distribution
- Decreased body fat percentage
- Decreased muscle
What effect does anesthesia induction have on infants?
- Higher incidence of cardiovascular instability and cardiac arrest
What two classes of medications do neonates have an increased sensitivity?
- Barbiturates
- Morphine
T/F, Neonates have a decreased response to pain relative to that of adults.
- False
- Physiologic response to pain is similar to adults
Because neonates are sensitive to barbiturates and morphine, what is a good alternative?
- Remifentanil
Relative to their body size, what is the proportion of neonatal lung volumes?
- Disproportionately small
What effect does the high metabolic rate and minute ventilation have in the oxygen consumption of neonates?
- 02 consumption per body weight is twice as high that of adults
What two factors put the neonate at high risk for desaturation?
- Less reserve lung volumes
- Less gas excahnge surface area
The increased Cardiac Output in the neonate has what effect on volatile anesthetic delivery?
- Increased delivery to vessel rich group
- Partial pressure of VAA in venous blood rapidly approaches that of alveoli and speeds FA/FI. “Whisking away”
What effect do more soluble VAA have on anesthetic delivery?
- Faster rate of rise of FA/FI
- Halothane, Isoflurane
What effect do less soluble VAA have on anesthetic delivery?
- No change from adults
- Sevoflurane, Desflurane
- What effect does a right/left shunt have on VAA delivery?
- Slows rate of rise of FA/FI, prolonged induction
- More “whisking away”
How are less soluble volatile agents effected in a right to left shunt?
- More prolonged induction compared to more soluble agents
- Soluble agents are already “whisked away” more in the alveoli. Therefore less soluble agents are more affected by the shunt.
What type of fluids are best to use with neonates
- Non-glucose containing (plasmalyte, LR)
Unless glucose is indicated
What is the normal hemoglobin range at birth for a neonate?
- 14-20 g/dL
What is the hematologic reason for increased risk of infection in neonates?
- Immature leukocyte function
What hematologic reasons puts the neonate at risk for hemorrhage?
- Immature liver causes low levels of Vitamin-K dependent factors
- All infants are administered Vitamin K
Which part of the Central Nervous System is dominant in utero?
- Parasympathetic Nervous System
What is the premature heart rate?
- 120-170 bpm
What is the mean heart rate at birth?
- 12o bpm
What is the normal heart rate range at one month?
- 100-160 bpm
What is the mean systolic blood pressure at birth?
- 65 mmHg
- Except in coarctation of the aorta, there is increased blood pressure in the upper extremities and decreased in the lower extremities
How does the neonate control cardiac output?
- Neonates are highly dependent on HR to maintain CO
- CO= 200 mL/kg/min
What are the factors that contribute to the rapid decompensation of the cardiac output of the neonate?
- Low compliance of ventricles
- Sensitivity to drugs that produce negative inotropic and chronotropic drugs
- Parasympathetic Nervous System is fully mature at birth
- Sympathetic Nervous System is immature at birth
What are the major physiologic implications of the neonatal renal system?
- Decreased ability to excrete saline
- Decreased ability to excrete water loads
- Decreased ability to excrete and drugs
- Normal renal function occurs at 6 months, reaches adult levels at 2 years old
- GFR is 15-30% at birth, reaches adult values by end of first year
Why does physiologic acidemia occur at birth?
- Low renal tubular threshold for bicarbonate (reduced acid buffer)
- Low level of production and excretion of urea
What is the major carrier protein in the fetus?
- Alpha fetoprotein
Albumin production begins in the first 3-4 months of gestation and levels are normal at birth. However, what albumin-dependent blood components remain low for the first few weeks of life?
- Clotting factors
What is a consequence of the immature liver in neonates?
- Impaired conjugation
- Increased bilirubin
- Drug metabolism is not effective in first few weeks of life
What are the primary causes of reflux in the neonate?
- Absent peristaltic waves in the lower esophageal sphincter
- Immature pharyngoesophageal sphincter
- LES becomes normal after 3-6 weeks
- 40% incidence of regurgitation in newborns
What GI condition is associated with neonatal apnea and bradycardia?
- GERD
- Peds should be induced with RSI
What three factors contribute to rapid heat loss to the environment in the neonate?
- Thin skin
- High surface area relative to weight
- low fat content
What condition delays awakening from anesthesia, causes cardiac irritability, respiratory depression, increased pulmonary resistance, and altered drug response?
- Hypothermia
- Please note that pulmonary resistance, cardiac irritability, and respiratory depression are all factors associated with persistent fetal circulation
Compared to adults, what are the anatomical differences of the neonatal tongue?
- Larger than in adults
- Difficulty viewing larynx
- Difficult to stabilize tongue with larygoscope
Describe Poiseuille’s Law.
- Resistance is inversely proportional to the 4th power of the radius
- Increased resistance in small airways
What is airway resistance in neonates? In adults? And what anatomical region is responsible for increased resistance?
- 19-28 cmH20/L/sec
- 2 cmH20/L/sec
- trachea-12th bronchial generation
- Resistance is normal at five years old
What is an anesthesia-related concern int he immature trachea?
- Tracheal collapse can occur during inspiration or expiration
- Airways may collapse without PEEP during PPV
What are the differences between the neonatal and the adult trachea?
- More cephalad in the neck
- @ level C3-C4 (C4-C5 in adults)
- Hyoid bone is at C2-C3
- Trachea is more anterior
Describe the neonatal epiglottis
- Narrow
- Omega-shaped (U-shaped)
- More difficult to lift with a laryngoscope
- Miller-0 or Miller-1 common in pediatrics
Describe the neonatal subglottic region
- The narrowest part of the larynx is the cricoid cartilage
- Funnel-shaped
- Edema of tracheal mucosa reduces luminal diameter and increases airway resistance (Poiseuille’s Law)
- Do not inflate cuff or use uncuffed ETT
What is the consequence of the narrow airways of the neonate?
- Obligate mouth breathers