Effects of nitric oxide inhalation on periodic breathing in awake patients with chronic heart disease.
BACKGROUND
Periodic breathing, an abnormal pattern of respiration consisting of alternating hyperpnea and hypopnea, has been recognized in patients with heart failure. Although fluctuations in pulmonary blood flow have been considered as a possible cause of this type of breathing, its patho-physiological mechanisms are not fully understood. In this study, we sought to determine whether inhaled nitric oxide (NO), a selective pulmonary vasodilator, attenuates periodic breathing.


METHODS
Eight cardiac patients who exhibited clear oscillatory ventilation while awake (age: 62 +/- 16 years, left ventricular ejection fraction: 48 +/- 20%) were enrolled in the study. After breathing room air (RA) for 15 min, the subjects inhaled air containing 30 ppm of NO for 15 min. Respiratory gas variables including minute ventilation (VE) were measured on a breath-by-breath basis throughout the test.


RESULTS
There were no differences in VE (10.7 +/- 1.5 vs. 11.0 +/- 1.7 l/min) or among any of the other hemodynamic or respiratory gas variables studied in the control and NO tests, with the exception of the end-tidal CO(2) partial pressure (5.0 +/- 0.4 vs. 4.8 +/- 0.5%; p = 0.018). The % magnitude of oscillation (i.e., the difference between the peak and nadir of oscillating VE, divided by the mean VE) was 40.0 +/- 22.4% in RA and not influenced by inhaled NO (43.9 +/- 20.8%, p = 0.57).


CONCLUSIONS
Inhaled NO at a concentration of 30 ppm did not attenuate periodic breathing in awake patients with mild heart failure.
Koike
Akira
A
The Cardiovascular Institute, Minato-ku, Tokyo, 106-0032 Japan. koike@cepp.ne.jp
Itoh
Haruki
H
Oohara
Reiko
R
Kubozono
Takuro
T
Koyama
Yoshiharu
Y
Shimizu
Noritaka
N
Aizawa
Tadanori
T
Iinuma
Hiroyuki
H
Fu
Long Tai
LT
D000280:Administration, Inhalation; D000368:Aged; D001993:Bronchodilator Agents / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006333:Heart Failure / Q000150:complications*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000008:administration & dosage / Q000494:pharmacology*; D010507:Periodicity; D012119:Respiration / Q000187:drug effects*
D001993:Bronchodilator Agents; D009569:Nitric Oxide