Evaluating the validity of responsiveness to inhaled nitric oxide in pediatric patients with ARDS: an analytic tool.

Abstract

OBJECTIVES: To determine whether improved oxygenation indicates a valid response to inhaled nitric oxide (iNO) therapy in patients with pediatric ARDS, and to establish an analytic tool to differentiate the iNO effects from those of other interactive factors in pediatric patients with ARDS. DESIGN: Consecutive case series evaluated by post hoc analysis tool. PATIENTS AND METHODS: Nineteen patients treated with iNO for ARDS or pulmonary hypertension were enrolled in our study. We evaluated the PaO(2)/fraction of inspired oxygen ratio (PF ratio), oxygenation index (OI), patient position (prone vs supine), PaCO(2), pH, and vasoactive drug support, and classified patients' responsiveness to iNO into three categories: (1) possible response, an increase in PF ratio, with no alteration of the aforementioned variables in a direction known to improve oxygenation; (2) nonspecific response, an increase in PF ratio with no increase in OI, and alteration of one or more of the other four criteria in a direction known to improve oxygenation; and (3) undetermined response, an increase in both the PF ratio and OI, indicating a deliberate augmentation in ventilator support. RESULTS: A total of 119 data points were evaluated. Fifty data points (42%) exhibited no response to iNO. Thirty-two data points (27%) were classified as having possible responses, 35 data points (29%) as nonspecific, and 2 data points (2%) as undetermined responses to the iNO treatment. CONCLUSIONS: In ARDS, improved oxygenation amid iNO treatment is multifactorial. In only 27% of our evaluated data points could the increase in PF ratio be attributed to iNO. We suggest that when clinically utilizing iNO, the interactive factors described by us should be taken into account for data analysis.