Shabih Manzar, MD, MPH

A preterm infant is admitted to the NICU for management of respiratory distress. The gestational age was 23 1/7 weeks, and the birth weight was 595 grams. The infant was intubated in the delivery room, and one dose (2.5 mL/kg) of surfactant was given. The x-ray was obtained after line placement (Figure 1, panel A). The infant was weaned to 21% O₂ while on the high-frequency ventilator. The blood gas from the umbilical arterial catheter showed a pHof 7.38/ pCO₂ 37, paO2 41, HCO3 22, and base deficit -2.3. At 10 hours of life, oxygen requirement went up to 70%. A repeat x-ray was obtained (Figure 1, panel B).

The NICU team was contemplating redosing with surfactant. However, based on the physical examination, a relatively clear lung field on the repeat x-ray and an oxygen saturation difference of 11% was noted between preductal (SpO₂ 95%) and postductal (84%); we decided to hold off on surfactant therapy suspecting persistent pulmonary hypertension (PPHN). An echocardiogram was ordered, and inhaled nitric oxide (iNO) was started as a rescue treatment for suspected PPHN. An immediate response was noted, and the infant was weaned back to 21% O₂ (Figure 1, panel C). The echocardiogram showed a patent ductus arteriosus, with a small, very low velocity left to right shunt consistent with near systemic RV systolic pressure.

[FIGURE 1: Lung x-rays at 45 minutes and 10 hours after birth, and response to INO]

Recently, Lanciotti et al. (1) described significant surfactant redosing in preterm infants born to mothers with hypertension in pregnancy and those who were small for gestational age (SGA). The authors mentioned the antiangiogenic environment caused by maternal hypertension and the possibility of fetal and neonatal pulmonary vasculature underdevelopment. Interestingly, their paper did not consider persistent pulmonary hypertension (PPHN) as a possible cause of increased O2 requirement in their cohort. Also, there was no mention of echocardiograms performed in infants requiring a second dose of exogenous surfactant. In a recent report, Mirza et al. (2) described the importance of recognizing PH in preterm infants. Although iNO is not a standard treatment in preterm infants with respiratory failure, it could be tried with the echocardiographic findings of PPHN (3).

Considering our anecdotal experience with the case described above, we would like to raise the question about surfactant redosing in preterm infants merely based on increased oxygen requirements without targeted neonatal echocardiography.

References:

1. Lanciotti L, Pasqualini M, Correani A, et al. Who Needs a Second Dose of Exogenous Surfactant? J Pediatr. 2023;261:113535. doi:10.1016/j.jpeds.2023.113535
2. Mirza H, Mandell EW, Kinsella JP, McNamara PJ, Abman SH. Pulmonary Vascular Phenotypes of Prematurity: The Path to Precision Medicine. J Pediatr. 2023;259:113444. doi:10.1016/j.jpeds.2023.113444
3. Stritzke A, Bhandari V, Lodha A. Use of Inhaled Nitric Oxide in Preterm Infants: Is There Sufficient Evidence?. Indian J Pediatr. 2022;89(3):262-266. doi:10.1007/s12098-021-03827-0

Disclosure: There are no disclosures noted.