Acute oxygenation response to inhaled nitric oxide when combined with high-frequency oscillatory ventilation in adults with acute respiratory distress syndrome

Objective. To prospectively evaluate the oxygenation effect of inhaled nitric oxide (INO) delivered during high-frequency oscillatory ventilation in adult patients with the acute respiratory distress syndrome and oxygenation failure. Design. Prospective, clinical study. Setting. Intensive care unit of a university teaching hospital. Patients: A total of 23 adults (14 women, 9 men, 44.9 +/- 17.5 yrs, Acute Physiology and Chronic Health Evaluation II score of 28.6 +/- 7.1) with acute respiratory distress syndrome (lung injury score, 3.5 +/- 0.4) with F10(2) of greater than or equal to0.6 and mean airway pressure of 28 cm H2O. Interventions: INO was initiated at a dose of 5 ppm, and subsequently titrated according to a protocol, to determine the dose (5, 10, or 20 ppm) resulting in the greatest increase in Pao(2)/F10(2). Blood gas measurements were obtained 10-15 mins after initiation or any increase in INO dosage to assess the effect on Pao(2)/F10(2). Measurements and Main Results. Arterial blood gases and ventilator settings were recorded at four time points: during conventional ventilation just before initiating high-frequency oscillatory ventilation, during high-frequency oscillatory ventilation just before initiating INO, after 30 mins on the optimal dose of INO, and 8-12 hrs after starting INO. Oxygenation index ([F10(2) X mean airway pressure x 100]/Pao(2)) and Pao(2)/F10(2) ratios were calculated at the same time intervals. At 30 mins after INO initiation, 83% of patients had a significant increase in blood oxygen tension, defined as greater than or equal to20% increase in Pao(2)/F10(2). The mean change in Pao(2)/F10(2) at 30 mins was 38%. In these 19 patients, Pao(2)/F10(2) was highest at 20 ppm in four patients, at 10 ppm in eight patients, and at 5 ppm in seven patients. Compared with baseline measurements, Pao(2)/f10(2) improved significantly at both 30 mins (112 +/- 59 vs. 75 +/- 32, p = .01) and 8-12 hrs after INO initiation (146 +/- 52 vs. 75 +/- 32, p < .0001). In addition, oxygenation index was reduced at 8-12 hrs compared with baseline measurements (26 +/- 13 vs. 40 +/- 17, p = .08). Conclusions. INO delivered at doses of 5 to 20 ppm during high-frequency oscillatory ventilation increases Pao(2)/F10(2) and may be a safe and effective rescue therapy for patients with severe oxygenationt failure. (Crit Care Med 2003; 31:383-389).