Design of a Virtual Instrument to Correlate Tagged Exhaled Nitric Oxide Breaths and Pulmonary Mechanics Measurements for Ventilated Pediatric Patients

The Biomedical Engineering Department at Texas Children's Hospital developed a portable virtual instrument using object oriented programming to combine an existing nitric oxide analyzer with a respiratory profile monitor. Pulmonary mechanics and exhaled nitric oxide (eNO) measurements for pre and post cardiopulmonary bypass procedures (CPB) are of primary concern to pediatric physicians. Patients with normal lung function prior to CPB demonstrate a transient gas exchange abnormality and some develop acute lung injury. The relationship of pulmonary mechanics to changes in eNO is described by opposing views (Pearl JM, 2000 and Morita K, 1996). As such, quantification of lung mechanics is important and can lead to better understanding of the mechanism for eNO changes and its clinical management. The goals of this project were twofold. First, to provide portable means for accurate measurements of eNO and pulmonary mechanics in the operating rooms and critical care environments. Second, to synchronize pulmonary mechanics data on a breath-by-breath basis with eNO tagged breaths. Validation procedure for respiratory profile monitor was performed and the average error (±SD) for compliance (ranges 2–8 ml/cm H2O) and volume measurements were 3.49% ± .11 and 1.99% ± .34 respectively. A portable system that met space and environment requirements for eNO is described as well as its ability to capture serial data streams from each device and correlation of nitric oxide analyzer tagged breaths with those of the respiratory profile monitor.

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