Clinical Studies
Combined effects of nitric oxide and oxygen during acute pulmonary vasodilator testing

Presented in part at the 45th Annual Scientific Sessions of the American College of Cardiology, Orlando, Florida, March 1996.
https://doi.org/10.1016/S0735-1097(98)00668-8Get rights and content
Under an Elsevier user license
open archive

Abstract

OBJECTIVES

We compared the ability of inhaled nitric oxide (NO), oxygen (O2) and nitric oxide in oxygen (NO+O2) to identify reactive pulmonary vasculature in pulmonary hypertensive patients during acute vasodilator testing at cardiac catheterization.

BACKGROUND

In patients with pulmonary hypertension, decisions regarding suitability for corrective surgery, transplantation and assessment of long-term prognosis are based on results obtained during acute pulmonary vasodilator testing.

METHODS

In group 1, 46 patients had hemodynamic measurements in room air (RA), 100% O2, return to RA and NO (80 parts per million [ppm] in RA). In group 2, 25 additional patients were studied in RA, 100% O2and 80 ppm NO in oxygen (NO+O2).

RESULTS

In group 1, O2decreased pulmonary vascular resistance (PVR) (mean ± SEM) from 17.2 ± 2.1 U·m2to 11.1 ± 1.5 U·m2(p < 0.05). Nitric oxide caused a comparable decrease from 17.8 ± 2.2 U·m2to 11.7 ± 1.7 U·m2(p < 0.05). In group 2, PVR decreased from 20.1 ± 2.6 U·m2to 14.3 ± 1.9 U·m2in O2(p < 0.05) and further to 10.5 ± 1.7 U·m2in NO+O2(p < 0.05). A response of 20% or more reduction in PVR was seen in 22/25 patients with NO+O2compared with 16/25 in O2alone (p = 0.01).

CONCLUSIONS

Inhaled NO and O2produced a similar degree of selective pulmonary vasodilation. Our data suggest that combination testing with NO+O2provides additional pulmonary vasodilation in patients with a reactive pulmonary vascular bed in a selective, safe and expeditious fashion during cardiac catheterization. The combination of NO+O2identifies patients with significant pulmonary vasoreactivity who might not be recognized if O2or NO were used separately.

Abbreviations

FiO2
fraction of inspired oxygen
NO
nitric oxide
NO2
nitrogen dioxide
O2
oxygen
Paco2
partial pressure of carbon dioxide, arterial
Pco2
partial pressure of carbon dioxide
ppm
parts per million
PVR
pulmonary vascular resistance
RA
room air

Cited by (0)

Dr. Atz is supported by an award from the National Institutes of Child Health and Human Development and a grant from the United States Food and Drug Administration. Dr. Wessel is supported by grants from the United States Food and Drug Administration and the Research Endowment of Children’s Hospital.