The Annals of Thoracic Surgery, Vol 44, 189-191, Copyright © 1987 by The Society of Thoracic Surgeons
Nitrous oxide for blood pressure control after coronary artery surgery: a dose-response hemodynamic study in postoperative patients
VJ DiSesa, JB Mark, JP Gold, F Kidwell, RJ Shemin, JJ Collins Jr and LH Cohn
The inhaled anesthetic nitrous oxide is used for sedation in the coronary
care unit and has been advocated as an antihypertensive agent in patients
after a cardiac operation. To delineate the hemodynamic effects of nitrous
oxide after cardiac surgery, we studied 11 patients with a mean age of 63
years who had undergone isolated coronary artery bypass grafting. All
patients had major coronary artery disease and normal preoperative
hemodynamic function. When patients were in stable condition in the
intensive care unit, hemodynamic measurements were made at an inspired
oxygen concentration of 40% with progressive doses of nitrous oxide (0, 10,
20, 40, and 60%). Measured and calculated hemodynamic data were compared
using analysis of variance. Nitrous oxide caused significant decreases in
mean arterial pressure in a dose- related fashion; pressure fell 6 mm Hg at
10% nitrous oxide and 11 mm Hg at 60% nitrous oxide (6 and 13% decreases).
These changes were not associated with significant alteration in pulmonary
artery pressure or cardiac index. Left ventricular stroke work index
decreased significantly with the administration of nitrous oxide. We
conclude that, in patients with normal hemodynamic and ventricular
function, the administration of nitrous oxide for its sedative and
antihypertensive effects is safe in the postoperative period and may be
useful, especially in patients who are candidates for early extubation.
