Nitric oxide inhalation as a chemical assist for circulation in patients after cardiovascular surgery

The objective of this study was to investigate whether nitric oxide (NO) in halation might be an alternative strategy as a chemical assist for the circ ulation in patients showing a deterioration in oxygen delivery. Twelve adul t patients whose oxygen delivery indices (Do,I) were less than 400 ml/min/m (2) after cardiovascular surgery were included in this study. NO was admini stered via a premixing system or a side stream system at doses between 1 an d 10 (5.1 +/- 2.4) ppm. Data obtained before and during a 120 min NO inhala tion were compared using the paired Student's t-test. The increase in Pao(2 )/Fio(2) resulting from NO inhalation was significant (from 162 to 251 mm H g). Do(2)I increased significantly from 326 to 417 ml/min/m(2) concomitantl y with significant increases in both arterial oxygen content (Cao,) and car diac index (CI) (from 14.1 to 15.4 vol% and from 2.31 to 2.71 L/min/m(2), r espectively). The increase in Svo(2) during NO inhalation was significant ( from 55.2 to 62.6%). Among the other hemodynamic parameters, both total pul monary resistance and systolic pulmonary arterial pressure (SPAP) showed si gnificant decreases during NO inhalation, but right atrial pressure did not change significantly. There was a close relationship between the baseline SPAP level (bSPAP) and the decrease in SPAP during NO inhalation (dSPAP) (r = -0.88). However, negative correlations were observed between bSPAP and p ercentage increase in CI (%CI) (r = -0.61) and between bSPAP and percentage increase in Do,I (%Do(2)I) (r = -0.48). Moreover, positive relationships w ere observed between dSPAP and %CI (r = 0.62) and between dSPAP and %Do(2)I (r = 0.45). Hemoglobin (Hb) increased significantly from 11.0 to 11.4 g/dl . There were no significant changes in Fio(2), pH, Paco(2), or base excess (BE) during NO inhalation. The level of methemoglobin measured during the s tudy period remained within the normal range (0.86 +/- 0.23%). In conclusio n, NO inhalation could be an efficient and alternative assist for the circu lation in patients whose oxygen delivery deteriorates after cardiovascular surgery.