The aim of this study was to assess whether hypoxemia during one-lung ventilation (OLV) can be prevented by inhaled nitric oxide (NO) (Part I) or by its combination with intravenous (IV) almitrine (Part II) in 40 patients undergoing thoracoscopic procedures. In Part I, 20 patients were divided into two groups: one received O2 (Group 1) and one received O2/NO (Group 2). In Part II, 20 patients were divided into two groups: one received O2 (Group 3) and one received O2/NO/almitrine (Group 4). In Groups 2 and 4, NO (20 ppm) was administered during the entire period of OLV, and almitrine was continuously infused (16 microg x kg(-1) x min[-1]) in Group 4. Arterial blood gases were measured during two-lung ventilation with patients in the supine position, after positioning in the lateral decubitus position, and then every 5 min for a 30-min period during OLV. During OLV, Pao2 values decreased similarly in Groups 1 and 2. After 30 min of OLV, the mean Pao2 values in Groups 1 and 2 were 132 +/- 14 mm Hg (mean +/- sem) and 149 +/- 27 mm Hg (not significant [NS]), and the Pao2 value was less than 100 mm Hg in four patients in Group 1 and five patients in Group 2. Pao2 values were greater in Group 4 than in Group 3 after 15 and 30 min of OLV. After 30 min of OLV, the mean Pao2 values were 146 +/- 16 mm Hg in Group 3 and 408 +/- 33 mm Hg in Group 4 (P < 0.001). Pao2 was less than 100 mm Hg during OLV (NS) in four patients in Group 3 and in no patient in Group 4. We conclude that NO inhalation alone has no effect on Pao2 evolution during OLV, although its combination with IV almitrine limits the decrease of Pao2 during OLV. This beneficial effect of NO/almitrine could be attributed to an improvement in ventilation-perfusion relationships.
Implications: Decrease in oxygenation during one-lung ventilation is quite common. Our study showed that inhaled nitric oxide alone did not influence Pao2 evolution. We then tried adding intravenous almitrine to nitric oxide with amazingly good results on Pao2. This nonventilatory technique should be of great use during special thoracic acts, such as thoracoscopic procedures.