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Pulmonary Medicine
Volume 2011 (2011), Article ID 189205, 6 pages
http://dx.doi.org/10.1155/2011/189205
Research Article

The Effect of Arterial pH on Oxygenation Persists Even in Infants Treated with Inhaled Nitric Oxide

1Department of Pediatrics, Georgetown University Hospital, 3800 Reservoir Road NW, M3400, Washington, DC 20007, USA
2Department of Pediatrics, Women and Infants Hospital, 101 Dudley Street, Providence, RI 02905, USA

Received 22 January 2011; Accepted 6 May 2011

Academic Editor: Irwin Reiss

Copyright © 2011 Aimee M. Barton et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Objective. To validate the empiric observation that pH has an important effect on oxygenation in infants receiving iNO. Study Design. Demographics, ventilator settings, arterial blood gases (ABG), and interventions for up to 96 hours of life were extracted from the charts of 51 infants receiving iNO. Need for ECMO and survival to discharge were noted. Mean blood pressure (MBP) and mean airway pressure (MAP) were recorded. The arterial/alveolar (a/A) ratio was used as the primary outcome. Analysis was by simple linear regression and multiple linear regression analyses and Fisher's exact test. pH responsiveness was arbitrarily defined as a correlation coefficient (CC) of >0.40 with 𝑃 < 0 . 0 5 . Results. Mean gestational age was 38.8 weeks and mean birth weight was 3300 g. All patients had clinical diagnosis of PPHN. Clear responsiveness to pH was found in 31/51 infants. MAP and MBP did not correlate with a/A ratio. Three responders had a critical pH > 7.55. Of 11 patients requiring ECMO, only 3 exhibited responsiveness at any time in their course. Three responders required ECMO. Conclusion. This small study suggests that failure or inability to optimize pH may account for observed unresponsiveness to iNO. Maintaining a pH > 7.5 using hyperventilation is not recommended.