Inhaled nitric oxide reverses hypoxic pulmonary vasoconstriction in dogs. A practical nitric oxide delivery and monitoring system.
Nitric oxide (NO) is a potent dilator of vascular smooth muscle that likely represents an important endothelium-dependent relaxing factor. Recent interest has focused on inhaled NO as a pulmonary vasodilator. The purpose of this study was to design a reliable NO delivery system with on-line monitoring of NO and nitrogen dioxide (NO2) concentrations, and to test the effects of inhaled NO in a dog model of acute hypoxic pulmonary vasoconstriction (HPV). Six canines were studied. Marked HPV was induced using a hypoxic gas mixture. Using a standard blender. NO was delivered through a volume-cycled ventilator. We were able to rapidly adjust the delivered NO concentration using this system. An on-line chemoluminescence analyzer was used to continuously measure NO and NO2 concentrations. Inhaled NO at 40 and 80 ppm for 30 min rapidly reversed HPV in all animals (PVR 502 +/- 154 dynes.s.cm-5 with hypoxia, 244 +/- 52 with 40 ppm NO, 227 +/- 47 with 80 ppm NO). No significant NO2 or methemoglobin production was noted during the study. We conclude that inhaled NO can be easily delivered through a ventilator and the dose rapidly adjusted, NO and NO2 concentrations can be monitored continuously on-line, inhaled NO rapidly reverses HPV in dogs, and with short-term NO inhalation, there is no significant NO2 or methemoglobin formation. Inhaled NO may, therefore, have a future clinical role as a new agent in the diagnosis and treatment of other forms of pulmonary hypertension.
Channick
R N
RN
Pulmonary and Critical Care Division, University of California, San Diego Medical School.
Newhart
J W
JW
Johnson
F W
FW
Moser
K M
KM
D000280:Administration, Inhalation; D000818:Animals; D004285:Dogs; D004867:Equipment Design; D000860:Hypoxia / Q000188:drug therapy*; D008163:Luminescent Measurements; D009569:Nitric Oxide / Q000008:administration & dosage / Q000032:analysis / Q000627:therapeutic use*; D009585:Nitrogen Dioxide / Q000032:analysis; D011651:Pulmonary Artery / Q000187:drug effects*; D011667:Pulmonary Veins / Q000187:drug effects*; D012138:Respiratory Therapy / Q000295:instrumentation*; D014661:Vasoconstriction / Q000187:drug effects; D012122:Ventilators, Mechanical
D009569:Nitric Oxide; D009585:Nitrogen Dioxide