Prod...Prematurity Flashcards
What is the definition of a premature infant?
Birth before 37 weeks gestation
What are the normal vital signs for a preterm infant?
- HR = 120 to 160
- RR = 30 to 60 (increase to 100 to 150 when lung compliance is decreased)
- BP of a 1000 gram baby 50/25
- BP of a 4000 gram baby 70/40
How are premature infants classified according to birth weight?
- <1000 grams = extreme low birth weight
Can digitalis be used to promote increased cardiac contractility int the premature infant?
- NO
- does not increase contractility or ventricular ejection, but it does slow the heart rate which is bad.
What is retinopathy of prematurity?
- occurs in half of babies <1500 grams
- Related to
- vasoconstriction of retinal vessels to high O2
- O2 radicals on retinal spindle cells
- induction of vascular endothelial growth factor
Why would indomethacin be administered to a premature neonate?
-Potent prostaglandin inhibitor (helps close the ductus arteriosus)
Is nitrous effective in premature infants?
Not really…it is a poor choice.
How does MAC compare between premature infants and full term infants.
-MAC is decreased in premature infants. (Can reduce systolic BP by 30%)
What airway abnormalities commonly associated with prematurity result in a decreased airway diameter and increased resistance to airflow?
- Subglottic stenosis
- Tracheal stenosis
- Tracheobronchomalacia
Which agents are commonly used in the treatment of apnea in the premature infant?
-Theophylline 10 mg/kg (converted into caffeine in the liver)
Why do premature infants have a decreased ability to compensate for hypovolemia?
- Immaturity of the contractile cells
- Immature autoregulation
- Anesthesia blunts the limited compensatory mechanism
What two significant condition can occur due to the presence of a patent ductus arteriosus?
- Pulmonary hypertension
- Congestive heart failure
How do low surfactant levels in the premature infant predispose th patient to hypoxia?
-Causes intrapulmonary shunting and V/Q mismatch resulting in hypoxia especially during anesthesia
What are the factors that contribute to the development of postoperative apnea in the premature infant?
- Postconceptual age < 50 - 60 weeks
- Hypothermia
- anemia
- necrotizing enterocolitis
- neurologic problems
- sepsis
What factor increases apnea the most postoperative?
-Postconceptual age < 50 - 60 weeks
How does the heart of a premature infant differ from that of a full term neonate?
- Premature hear contain more connective tissue
- Contractile elements are less organized
- contractility has more dependence upon the extracellular calcium concentration
What are the treatment regimens for postoperative apnea in the premature infant?
- Cardiorespiratory monitoring
- correction of anemia or hypovolemis
- IV caffeine to stimulate respiration (Theophylline)
- Nasal CPAP
Does regional anesthesia eliminate the risk for postoperative apnea in the premature infant?
-NO (only reduces apnea)
What are the effects of increased pulmonary vascular resistance on a patient with a patent ductus arteriosus?
-Increase the right to left shunt
What is the definition of postoperative apnea?
- Apnea greater than 15 second
- Apnea that is accompanied by bradycardia
Why is apnea common postoperatively in premature infants?
Anesthetic combined with the underdeveloped medullary respiratory control center predispose the patient to:
- Hypercapnia
- hypoxia
- apnea
Does the premature infant’s heart exhibit a greater or less sensitivity to catecholamines?
Less sensitive to catecholamines due to maximal level of beta adrenergic stimulation
What are the ventilatory goals during the anesthesia of a premature infant?
- minimize inspired O2 concentraion and peak inspiratory pressures
- Have adequate O2 and ventilation
When does surfactant production in the lungs begin?
23 - 24 weeks (typically inadequate until 36 weeks of gestation)
