The initial response to inhaled nitric oxide treatment for intensive care unit patients with acute respiratory distress syndrome.
BACKGROUND
Inhaled nitric oxide (INO) can improve hypoxemia and reduce pulmonary hypertension, but there is a wide range of response to INO.


OBJECTIVE
The aim of this study was to evaluate the effect of different INO concentrations in acute respiratory distress syndrome (ARDS) patients.


METHODS
Thirty-two adult ARDS patients who were supported by mechanical ventilator were included. INO was given at a concentration of 1, 5, 10, 20 and 40 ppm, sequentially. Arterial blood gas and mean pulmonary artery pressure (MPAP) were measured 30 min after INO concentrations changed.


RESULTS
There was a significant increase in PaO(2)/FiO(2) (p < 0.0001) and a decrease in pulmonary vascular resistance index and MPAP (p < 0.0001) after INO use. INO concentrations required for improving oxygenation were in the range of 1-20 ppm, whereas concentrations required for decreasing MPAP were in the range of 1-40 ppm. PaO(2)/FiO(2) worsened when the INO dose was adjusted above 20 ppm. Sixty-nine percent of ARDS patients were responders; 31% of them were nonresponders. Among responders, 64% of patients responded at 1 ppm, 36% at 5 ppm.


CONCLUSIONS
The optimal doses for improving oxygenation and reducing PAP differ. The maximum PaO(2)/FiO(2) was observed at a lower INO concentration than that required for the minimal MPAP. There was no further improvement in PaO(2)/FiO(2) when the INO dose was adjusted above 20 ppm. Higher doses of INO treatment worsened oxygenation.
Hsu
Chien-Wei
CW
Intensive Care Unit, Internal Medicine Department, Veterans General Hospital Kaohsiung, Kaoshiung, Taiwan, ROC. cwhsu2003@yahoo.com
Lee
David Lin
DL
Lin
Shoa-Lin
SL
Sun
Shu-Fen
SF
Chang
Hsueh-Wen
HW
D018806:APACHE; D000280:Administration, Inhalation; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004305:Dose-Response Relationship, Drug; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000008:administration & dosage*; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange; D012128:Respiratory Distress Syndrome / Q000188:drug therapy* / Q000453:epidemiology; D012307:Risk Factors; D016896:Treatment Outcome
D009569:Nitric Oxide