Prone positioning and inhaled nitric oxide: synergistic therapies for acute respiratory distress syndrome.
BACKGROUND
Inhaled nitric oxide (INO) and prone positioning have both been advocated as methods to improve oxygenation in patients with acute respiratory distress syndrome (ARDS). This study was designed to evaluate the relative contributions of INO and prone positioning alone and in combination on gas exchange in trauma patients with ARDS.


METHODS
Sixteen patients meeting the consensus definition of ARDS were studied. Patients received mechanical ventilation in the supine position, mechanical ventilation plus INO at 1 part per million in the supine position, mechanical ventilation in the PP, and mechanical ventilation in the prone positioning plus INO at 1 part per million. A stabilization period of 1 hour was allowed at each condition. After stabilization,hemodynamic and gas exchange variables were measured.


RESULTS
INO and prone positioning both increased PaO2/FIO2 compared with ventilation in the supine position. PaO2/FIO2 increased by 14% during use of INO, and 10 of 16 patients (62%) responded to INO in the supine position. PaO2/FIO2 increased by 33%, and 14 of 16 patients (87.5%) responded to the prone position. The combination of INO and prone positioning resulted in an improvement in PaO2/FIO2 in 15 of 16 patients(94%), with a mean increase in PaO2/FIO2 of 59%. Pulmonary vascular resistance was reduced during use of INO, with a greater reduction in pulmonary vascular resistance seen with INO plus prone positioning (175 +/- 36 dynes x s/cm5 vs. 134 +/- 28 dynes x s/cm5) compared with INO in the supine position (164 +/- 48 dynes x s/cm5 vs.138 +/- 44 dynes x s/cm5). There were no significant hemodynamic effects of INO or prone positioning and no complications were seen during this relative short duration of study.


CONCLUSIONS
INO and prone positioning can contribute to improved oxygenation in patients with ARDS. The two therapies in combination are synergistic and may be important adjuncts to mechanical ventilation in the ARDS patient with refractory hypoxemia.
Johannigman
J A
JA
Department of Surgery, University of Cincinnati, College of Medicine, Ohio 45267-0558, USA. jay.johannigman@uc.edu
Davis
K
K
Miller
S L
SL
Campbell
R S
RS
Luchette
F A
FA
Frame
S B
SB
Branson
R D
RD
D000280:Administration, Inhalation; D000328:Adult; D000368:Aged; D001784:Blood Gas Analysis; D001993:Bronchodilator Agents / Q000008:administration & dosage*; D003131:Combined Modality Therapy; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D009104:Multiple Trauma / Q000150:complications; D009569:Nitric Oxide / Q000008:administration & dosage*; D010100:Oxygen / Q000097:blood; D011175:Positive-Pressure Respiration / Q000379:methods; D016684:Prone Position; D011446:Prospective Studies; D011652:Pulmonary Circulation / Q000187:drug effects; D011659:Pulmonary Gas Exchange / Q000187:drug effects; D011669:Pulmonary Wedge Pressure / Q000187:drug effects; D012128:Respiratory Distress Syndrome / Q000209:etiology / Q000378:metabolism / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D016683:Supine Position; D016019:Survival Analysis; D016896:Treatment Outcome; D014655:Vascular Resistance / Q000187:drug effects
D001993:Bronchodilator Agents; D009569:Nitric Oxide; D010100:Oxygen