Journal of cardiothoracic anesthesia
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J Cardiothorac Anesth · Oct 1989
The mechanism of nitrous oxide-induced changes in pulmonary vascular resistance in a dog model of left atrial outflow obstruction.
Nitrous oxide has been reported to increase pulmonary vascular resistance (PVR) in patients with pulmonary hypertension secondary to mitral stenosis. Additional data suggest this response involves sympathetic stimulation because the increase in PVR can be prevented by alpha-adrenergic and ganglionic blockade. Whether or not active pulmonary vasoconstriction occurs remains unclear. ⋯ The inspired gas was then changed to 67% N2O and 33% O2 for 10 minutes, and then returned to the N2/O2 mixture. Once baselines had been reestablished (about 10 minutes), phentolamine, 0.75 mg/kg, was administered, and the response to 10 minutes of N2O again observed. N2O did not change vascular resistance in the isolated lobe, but increased intact-lung PVR.(ABSTRACT TRUNCATED AT 250 WORDS)