Neonatal Med.  2020 Aug;27(3):133-140. 10.5385/nm.2020.27.3.133.

Response to Inhaled Nitric Oxide and Clinical Outcome in Very Low Birth Weight Infants with Early Pulmonary Hypertension

• Cho JY
• Lee BS
• Oh MY
• Cha T
• Jeong J
• Jung E
• Kim AR
• Kim KS

• KMID: 2505664
• DOI: http://doi.org/10.5385/nm.2020.27.3.133

Abstract

Purpose
To determine the efficacy of inhaled nitric oxide (iNO) in very low birth weight (VLBW) infants with early pulmonary hypertension (PH).
Methods
We reviewed the medical records of 22 preterm infants who were born <30 weeks of gestational age with birth weight <1,500 g, diagnosed with early PH, and treated with iNO within the first 72 hours after birth. Responders were defined by a reduction in FiO 2 >20% and/or oxygenation index (OI) >20% from the baseline values at 1 hour after beginning iNO therapy. Cardiorespiratory support indices including OI, oxygen saturation index, and vasoactive-inotropic score (VIS) were serially obtained for 96 hours following iNO therapy.
Results
The mean gestational age of the patients was 26.1±2.0 weeks and the mean birth weight was 842±298 g. The mean OI at the start of iNO was 63.8±61.0. Impro vement in oxygenation indicated by prompt decrease in FiO 2 and OI from the base line values were observed 1 hour after beginning iNO therapy and lasted up to 96 hours. After iNO therapy, VIS increased until 24 hours and decreased thereafter. At 1 hour after iNO, 16 patients (73%) were classified as responders and six (27%) as nonresponders. Compared with nonresponders, responders did not demonstrate the beneficial effect of iNO in terms of short-term survival and neonatal complications. The 1-year mortality rate did not differ between responders (56%) and nonresponders (67%).
Conclusion
Although iNO treatment immediately improved oxygenation in most VLBW infants with early severe PH, the long-term mortality rate was high. A largescale study is needed to determine whether the initial response to iNO can predict patients’ survival.

Keyword

Infant, very low birth weight; Hypertension, pulmonary; Nitric oxide

Figure

• 

  Figure 1. Flow chart of the study population. A total of 22 preterm infants were included in the analysis. Sixteen infants (72%) are classified as responders to inhaled nitric oxide, and six infants (28 %) as nonresponders. Abbreviations: iNO, inhaled nitric oxide; GA, gestational age.

• 

  Figure 2. Comparison of treatment response to inhaled nitric oxide between the responders and nonresponders. (A) Oxygenation index (OI), (B) oxygen saturation index (OSI), (C) fraction of inspired oxygen (FiO2), (D) vasoactive-inotropic score (VIS). Each vertical line represents confidence interval and each dot on the line represents predicted value.

• 

  Figure 3. Kaplan-Meier survival estimates of infants in the responders and nonresponders.

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