Response to nitric oxide inhalation in early acute lung injury.
OBJECTIVE
To evaluate the dose response of inhaled nitric oxide (NO) on gas exchange and central haemodynamics in patients with early acute lung injury (ALI).


METHODS
Prospective, multicentre clinical study.


METHODS
General ICUs in university and regional hospitals.


METHODS
18 Patients with early ALI according to specified criteria.


METHODS
During controlled ventilation an inhalation system was used to deliver NO (1000 ppm in N2) and O2/air to the low pressure fresh gas inlet of a Siemens 900C ventilator. Haemodynamics and pulmonary gas exchange variables were measured at baseline and at stepwise increased inspiratory NO concentrations of 0.1, 0.3, 1, 3, 10, 30 and 100 ppm, each dose being maintained for 15 min. Dose testing was repeated the next day, and the response to prolonged (2 h) NO inhalation at 1 and 10 ppm was also tested.


RESULTS
Inhalation of NO produced a significant increase in PaO2 (P < 0.0025). The degree of response, as well as the optimal NO dose varied in individual patients and between different days. Venous admixture (QVA/QT) was reduced (P < 0.02) from 38% (31-46%) to 33% (26-41%). In our patients with early acute lung injury and only a moderate elevation in pulmonary arterial pressure NO inhalation did not reduce mean pulmonary artery pressure significantly, being 27.0 (21-30) mmHg at baseline and 26.0 (21-30) mm Hg at 100 ppm.


CONCLUSIONS
This study shows that improvements in arterial oxygenation in response to inhaled NO may show great inter- as well as intraindividual variability, and that improvements in arterial oxygenation occur without any measurable lowering of the pulmonary artery pressure.
Lundin
S
S
Department of Anaesthesia and Intensive Care, Sahlgrenska University Hospital, Göteborg, Sweden.
Westfelt
U N
UN
Stenqvist
O
O
Blomqvist
H
H
Lindh
A
A
Berggren
L
L
Arvidsson
S
S
Rudberg
U
U
Frostell
C G
CG
D000280:Administration, Inhalation; D000328:Adult; D000368:Aged; D004305:Dose-Response Relationship, Drug; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D008875:Middle Aged; D009569:Nitric Oxide / Q000494:pharmacology* / Q000627:therapeutic use; D010100:Oxygen / Q000097:blood; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange / Q000187:drug effects*; D011669:Pulmonary Wedge Pressure / Q000187:drug effects; D012121:Respiration, Artificial; D012128:Respiratory Distress Syndrome / Q000188:drug therapy / Q000503:physiopathology*; D018709:Statistics, Nonparametric
D009569:Nitric Oxide; D010100:Oxygen