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Inhaled nitric oxide enhances oxygenation but not survival in infants with alveolar capillary dysplasia
R H Steinhorn1, P N Cox, J R Fineman
1Department of Pediatrics, Children's Hospital, Buffalo, NY 14222, USA.
Insights
Alveolar capillary dysplasia (ACD) is a lung vascular abnormality causing persistent pulmonary hypertension. Inhaled nitric oxide (NO) offers only temporary improvement, not long-term survival, in infants with ACD.
Area of Science:
- Neonatal Medicine
- Pediatric Cardiology
- Pulmonary Medicine
Background:
- Alveolar capillary dysplasia (ACD) is a rare congenital lung vascular malformation.
- It is increasingly recognized in infants with persistent pulmonary hypertension of the newborn (PPHN).
- Infants with ACD and PPHN often have refractory hypoxemia and poor outcomes despite maximal support, including ECMO.
Purpose of the Study:
- To evaluate the efficacy and long-term impact of inhaled nitric oxide (NO) in neonates with confirmed alveolar capillary dysplasia (ACD).
- To assess the clinical course and survival of infants with ACD treated with inhaled NO.
Main Methods:
- Retrospective case series of five infants with autopsy-confirmed ACD and PPHN.
- Inhaled nitric oxide (NO) was administered to treat refractory hypoxemia.
- Clinical data, response to NO, need for ECMO, and survival were analyzed.
Main Results:
- Inhaled NO initially improved oxygenation (PaO2) in all five infants.
- The beneficial response to NO was transient and not sustained in any patient.
- Increasing concentrations of NO (≥80 ppm) were required to maintain oxygenation as responsiveness diminished.
- Four infants ultimately required extracorporeal membrane oxygenation (ECMO) support.
- All five infants died, with diagnoses confirmed by autopsy or lung biopsy.
Conclusions:
- Inhaled nitric oxide (NO) provides only short-term hemodynamic and oxygenation benefits in infants with alveolar capillary dysplasia (ACD).
- NO does not improve long-term survival in this condition.
- Increased awareness of ACD is crucial to avoid prolonged, invasive, and costly treatments like ECMO before definitive therapies are available.
Abstract:
A complex vascular abnormality in the lungs, termed alveolar capillary dysplasia (ACD) and misalignment of the lung vessels, has been recently recognized in some infants with persistent pulmonary hypertension. These infants die despite maximal medical support including extracorporeal membrane oxygenation (ECMO). Inhaled nitric oxide has been reported to improve oxygenation in neonates with persistent pulmonary hypertension of the newborn, and may allow some infants to avoid the need for ECMO. We identified five infants who had received inhaled nitric oxide to treat refractory hypoxemia caused by persistent pulmonary hypertension of the newborn, and who subsequently died and had autopsy confirmation of ACD. Each infant received care at a different medical center. In each patient, inhaled NO increased the arterial partial pressure of oxygen dramatically. Despite initial clinical improvement, the response to NO was not sustained in any patient. As responsiveness was lost, each infant with ACD required inhaled NO concentrations of 80 ppm or higher to sustain oxygenation. Each infant died, four after extensive periods of ECMO support. This experience demonstrates that a short-term improvement after inhalation of nitric oxide does not lead to long-term survival in ACD. Further, in three infants the diagnosis of ACD was established by lung biopsy before death. Increasing awareness of this clinical entity may allow for the avoidance of costly, invasive procedures such as ECMO until more specific therapies become available.
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