Low- vs high-dose almitrine combined with nitric oxide to prevent hypoxia during open-chest one-lung ventilation

Abstract

Background. Almitrine combined with inhaled nitric oxide (NO) can prevent hypoxia during one-lung ventilation (OLV). The optimal dose of almitrine that would provide therapeutic advantage with few side-effects during open-chest OLV has not been established. Methods. Forty-two patients undergoing thoracotomy were randomly allocated to three groups: placebo, almitrine 4 μg kg-1 min-1 and inhaled NO 10 p.p.m. (ALM4+NO), and almitrine 16 μg kg-1 min-1 and inhaled NO 10 p.p.m. (ALM16+NO). Gas exchange, haemodynamic and respiratory variables and plasma concentrations of almitrine and lactate were monitored. Measurements were obtained with the patient awake (baseline), after induction of anaesthesia with two-lung ventilation (control 2LV), 20 min after treatment (2LV+T), and then at 10, 20 and 30 min of OLV (OLV10′, OLV20′ and OLV30′) with FlO21. Results. In the placebo group, OLV impaired PaO2 and increased pulmonary shunt [16 (SD7) kPa and 42 (10)% respectively]. These improved with ALM4+NO [26 (10) kPa and 31 (7)%; P<0.001]. ALM16+NO further improved PaO2 to 36 (13) kPa (P<0.0001) but gave no improvement in the shunt. Mean pulmonary artery pressure was similar in the placebo and ALM4+NO groups [20 (4) vs 23 (5) mm Hg], whereas it was increased in the ALM16+NO group to 28 (8) mm Hg (P<0.01). Plasma concentrations of almitrine and lactate were unaltered by the treatments. Conclusions. Low-dose almitrine (4 μg kg-1 min-1) together with inhaled NO significantly improves oxygenation during open-chest OLV, without modifying pulmonary haemodynamics. An increased dose of almitrine (16 μg kg-1 min-1) with inhaled NO further improves arterial oxygenation, but also increases mean pulmonary artery pressure. © The Board of Management and Trustees of the British Journal of Anaesthesia 2005. All rights reserved.