Am. J. Respir. Crit. Care Med., Vol 151, No. 1, 01 1995, 116-122.
Improvement in VA/Q distributions during inhalation of nitric oxide in pigs with methacholine-induced bronchoconstriction
C Putensen, J Rasanen and FA Lopez
Department of Anesthesiology, University of South Florida, College of Medicine, Tampa 33612-4799.
Effects of nitric oxide (NO) and aerosolized terbutaline inhalation on
ventilation-perfusion (VA/Q) distributions were determined during
methacholine-induced bronchoconstriction in nine mechanically ventilated
pigs. Animals inhaled, in random order, zero, 20, and 80 parts per million
(ppm) of NO or aerosolized terbutaline. Inhalation of either 20 ppm NO or
terbutaline produced similar reduction in pulmonary resistance and increase
in lung compliance. Bronchodilation was most pronounced during inhalation
of 80 ppm NO. NO inhalation increased PaO2 from 65 +/- 4 to 90 +/- 5 (20
ppm NO) and 104 +/- 6 mm Hg (80 ppm NO) (p < 0.05), and oxygen delivery
(DO2) from 484 +/- 49 to 565 +/- 25 (20 ppm NO) and 619 +/- 43 ml/kg/min
(80 ppm NO) (p < 0.05) compared with control. Aerosolized terbutaline
did not increase PaO2 and DO2. NO inhalation accounted for a decrease in
blood flow to shunt units (20 ppm NO: 14 +/- 1%, 80 ppm NO: 19 +/- 2%; p
< 0.05) and an increase in the perfusion of normal VA/Q units (20 ppm
NO: 12 +/- 1%, 80 ppm NO: 18 +/- 1%; p < 0.05). Perfusion of shunt and
normal VA/Q units was similar in the absence of NO inhalation with and
without aerosolized terbutaline. Pulmonary vascular resistance decreased
from 510 +/- 55 to 332 +/- 22 dyn.s/cm5 with 20 ppm NO (p < 0.05) and to
329 +/- 41 dyn.s/cm5 with 80 ppm NO (p < 0.05) but did not change with
terbutaline.(ABSTRACT TRUNCATED AT 250 WORDS)