Short-term effects of inhaled nitric oxide and prone position in pulmonaryand extrapulmonary acute respiratory distress syndrome

Inhaled nitric oxide (NO) and prone position (PP) are frequently used in th e treatment of acute respiratory distress syndrome (ARDS). We compared the gas exchange and hemodynamic effects induced by the combination of NO inhal ation and PIP in patients with ARDS and analyzed whether or not pulmonary ( Pu) and extrapulmonary (Epu) ARDS patients behave differently. Eight Pu and seven Epu ARDS patients were studied in four situations: supine position ( SP); SP with NO inhalation at 5 ppm (SP + NO); PP; and PP with NO inhalatio n (PP + NO). In comparison with SP, NO inhalation and PP induced significan t increases in Pa-O2/Fl(O2) (from 106 +/- 58 in SP to 131 +/- 69 mm Hg in S P + NO, p = 0.01, and to 184 +/- 67 mm Hg in PP, p < 0.001). Pu and Epu ARD S showed a similar improvement in Pa-O2 /Fl(02) with PP. Only Pu ARDS patie nts showed a significant increase (p < 0.001) in oxygenation induced by NO inhalation from 81 +/- 45 to 100 +/- 50 mm Hg in SP, and from 146 +/- 53 to 197 +/- 98 mm Hg in PP. In conclusion, PP is associated with a marked impr ovement in oxygenation, irrespective of the causes of ARDS, and additive ef fects of NO inhalation are mainly seen in patients with Pu ARDS.