CPAP Failure in a Very Preterm Infant With RDS
A 28-week, 1,100-g male infant is 6 hours old in the NICU. He was born by emergency cesarean delivery for fetal bradycardia. The mother received one dose of antenatal betamethasone 12 hours before delivery. He is on nasal CPAP 6 cm H2O with FiO2 0.35. SpO2 is 88% to 92%, respiratory rate 72/min, with grunting, subcostal retractions, and nasal flaring; Silverman-Andersen score is 7. Arterial blood gas: pH 7.22, PaCO2 58 mm Hg, PaO2 50 mm Hg, HCO3 21 mEq/L. Chest radiograph shows low lung volumes with diffuse reticulogranular opacities and air bronchograms; no pneumothorax. He has received no surfactant. He has had two apneic episodes requiring stimulation in the last hour. The resident asks whether this is CPAP failure and whether to intubate for surfactant or continue CPAP.
1. Does this infant meet criteria for CPAP failure? Justify using the FiO2 requirement, blood gas, and clinical signs.
Read the worked answer
Yes. CPAP failure is commonly judged by a need for FiO2 above 0.30–0.40 to maintain the target SpO2, persistent severe respiratory distress, recurrent apnea, or worsening respiratory acidosis. This infant needs FiO2 0.35 but still has SpO2 88–92%, a Silverman-Andersen score of 7, two apneic episodes in one hour, and a blood gas with pH 7.22 and PaCO2 58 mm Hg. The radiograph is classic for respiratory distress syndrome, and he has not received surfactant. Continuing CPAP alone would risk fatigue, worsening acidosis, and a crash intubation. The appropriate judgement is that CPAP is failing and surfactant is indicated now, not after further deterioration. If the team elects less-invasive surfactant administration, it should be done urgently with experienced personnel and readiness to intubate.
2. Compare LISA and INSURE for surfactant administration. Which would you choose here and why? Include drug and dose, and what you monitor.
Read the worked answer
LISA delivers surfactant through a thin catheter while the infant breathes spontaneously on CPAP, avoiding intubation; it requires an experienced operator and a breathing infant. INSURE means intubate, give surfactant, and extubate back to CPAP; it is more reliable when apnea or severe distress makes LISA unsafe. Because this infant has already had recurrent apneas, INSURE or a brief intubation is the safer choice unless the NICU has a highly experienced LISA team and can manage the airway immediately. Typical doses are poractant alfa 200 mg/kg (2.5 mL/kg) initially or beractant 100 mg/kg (4 mL/kg). Monitor heart rate, SpO2, chest rise, endotracheal tube position, blood glucose, and blood gas. Watch for pneumothorax, pulmonary hemorrhage, and bradycardia during administration. Start or continue caffeine for apnea of prematurity.
3. State the SpO2 and PaCO2 targets after surfactant and list two complications that change your monitoring.
Read the worked answer
Target SpO2 90–95%, avoiding sustained hyperoxia, and target PaCO2 approximately 45–55 mm Hg with permissive hypercapnia up to about 60 mm Hg if pH remains above 7.20. PaO2 is usually kept around 50–70 mm Hg. After surfactant, compliance improves rapidly, so FiO2 often needs to be reduced to avoid hyperoxia. Two complications that should change monitoring are pneumothorax and pulmonary hemorrhage. Pneumothorax may present with sudden desaturation, asymmetric chest movement, hypotension, or bradycardia; pulmonary hemorrhage may cause fresh blood from the airway and sudden worsening gas exchange. Also monitor for patent ductus arteriosus, intraventricular hemorrhage, and bronchopulmonary dysplasia.