P2C177: Echocardiographic Evidence of Pulmonary Hypertension and Oxygenation Response Predict Survival Following Nitric Oxide Therapy in Preterm Infants

Background: Inhaled nitric oxide (iNO) is approved by FDA in term infants for treatment of hypoxemic respiratory failure (HRF). Routine rescue therapy for preterm infants with HRF with iNO is not recommended by AAP. However, American Heart Association guidelines recommend selective therapy with iNO in the presence of pulmonary hypertension physiology. Selective use of iNO in subcategories of preterm infants with HRF where it has been shown to improve survival may potentially reduce costs.

Methods: We conducted a retrospective individual case review of < 34-week gestation preterm infants exposed to iNO during 2010-2020 in Kaiser Permanente Southern California healthcare system. We evaluated FiO2, SpO2, SpO2/FiO2 (S/F) ratio and echocardiographic findings at initiation of iNO. Response to iNO was defined as an increase in S/F ratio by >/= 30 by 2 hours after initiation.

Results: Between 2010-20, 270 preterm infants (median, range: 26.1, 22 5/7-33 5/7 weeks’ gestation, mean weight 783g, range 270-3200g birth weight) were exposed to iNO, representing 2.63% of infants born at < 34 weeks’ gestation. Median FiO2 at initiation of iNO was 1.0 (IQR 0.94-1.0). Survival to discharge overall was 63% (169/270). 58% of iNO exposure was initiated during the first postnatal week. 43 infants had echocardiograms done < 24h prior to initiation of iNO during the first postnatal week and 29 of them had evidence of pulmonary hypertension (PH) and had higher survival (76%) compared to infants without PH (36%) - figure 1.
Oxygenation responders (with increase in SpO2/FiO2 >/= 30) by 2 hours of iNO initiation had better survival compared to infants with low or no oxygenation response (table 1)

Conclusion: Presence of echocardiographic evidence of pulmonary hypertension prior to initiation of iNO and immediate oxygenation response to iNO are predictive of survival. These findings support the current AHA guidelines recommending the use of iNO selectively in preterm infants with pulmonary hypertension physiology. These criteria can potentially be incorporated into guidelines for initiation and continuation of iNO in preterm infants.