Exhaled nitric oxide level decreases after cardiopulmonary bypass in adultpatients

Objective: To measure exhaled nitric oxide (NO) and compare it with lung fu nction after cardiopulmonary bypass (CPB) in adult patients. Pulmonary dysf unction is sometimes observed after CPB. Impaired production of NO may acco unt for this dysfunction. Design: Prospective, single-center, observational study. Setting: University hospital operating room, intensive care unit. Patients: Sixteen adult patients undergoing cardiac surgery with CPB. Interventions: None except cardiac surgery with OPE. Measurements and Main Results: Exhaled NO was measured continuously by the chemiluminescence method and was expressed as the peak and mean NO concentr ations, and the NO output (V-NO). These parameters were calculated by avera ging four sequential tidal NO values. The data were obtained serially from before CPB to 16 hrs after GPB. Lung function was evaluated by monitoring l ung compliance, pulmonary artery pressure, and alveolar-arterial oxygen dif ference (P(A-a)O-2). The cardiac index did not change except for a signific ant increase at 16 hrs compared with 6 hrs after CPB. Peak NO, mean NO, and V-NO decreased from 15.4 +/- 2.0 ppb (before OPE) to 8.2 +/- 0.8 ppb (6 hr s after CPB), from 5.7 +/- 0.7 ppb to 2.8 +/- 0.6 ppb, and from 29.2 +/- 3. 1 nL/min to 15.7 +/- 2.2 nL/min, respectively These changes were associated with the increases in pulmonary artery pressure and alveolar-arterial oxyg en difference, and the decrease in lung compliance. V-NO recovered to the l evel measured before CPB 16 hrs after CPB, which was consistent with the ph ysiologic recovery in pulmonary hypertension, lung compliance, and gas exch ange. Conclusion: Measurement of exhaled NO as V-NO, which was associated with lu ng dysfunction, may he an indicator of lung injury in adult patients after cardiopulmonary bypass.