Effects of inhaled nitric oxide on respiratory system mechanics, hemodynamics, and gas exchange after cardiac surgery.
OBJECTIVE
To evaluate the hemodynamic and respiratory effects of inhaled nitric oxide (NO) in postoperative cardiac patients.


METHODS
A prospective evaluation.


METHODS
A university hospital intensive care unit.


METHODS
Fourteen adults with pulmonary hypertension, studied postoperatively.


METHODS
60 minutes of NO inhalation (20 ppm).


RESULTS
Respiratory mechanics were analyzed by inflating the relaxed respiratory system with constant flow, followed by rapid airway occlusion at end-inflation, which was maintained until a plateau in tracheal pressure was obtained. Gas exchange and hemodynamics were evaluated by conventional means. The data were studied using the analysis of variance for repeated measures. Minimum airway resistance (Rmin) increased significantly from 8.87+/-3.24 cm H2O/L x s to 9.69 +/-3.22 cm H2O/L x s at the end of NO inhalation and remained elevated after NO was discontinued. A selective vasodilator effect on pulmonary vasculature was observed in the pulmonary-systemic vascular resistance ratio, which decreased from 0.18+/-0.11 to 0.13+/-0.08 at the end of inhalation and returned to baseline values after gas suspension. No significant alterations in oxygenation were observed.


CONCLUSIONS
The effects of NO as a powerful and useful vasodilator agent were confirmed. However, it is important to be aware that the effects observed on respiratory mechanics may interfere with the final response of the respiratory system to NO.
Carmona
M J
MJ
Department of Anesthesiology and Intensive Care, Heart Institute of the University of São Paulo-Hospital das Clinicas, Brazil.
Auler
J O
JO
D000280:Administration, Inhalation; D000328:Adult; D000368:Aged; D000403:Airway Resistance / Q000187:drug effects; D006348:Cardiac Surgical Procedures; D005260:Female; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D006976:Hypertension, Pulmonary / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000008:administration & dosage / Q000494:pharmacology*; D011184:Postoperative Period; D011652:Pulmonary Circulation / Q000187:drug effects; D011659:Pulmonary Gas Exchange / Q000187:drug effects*; D012119:Respiration / Q000187:drug effects*; D012189:Retrospective Studies; D014655:Vascular Resistance / Q000187:drug effects; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000494:pharmacology*
D014665:Vasodilator Agents; D009569:Nitric Oxide