Inhaled olprinone improves contractility of fatigued canine diaphragm

Background. Diaphragmatic fatigue is implicated as a cause ofrespiratory failure. This study was undertaken to evaluate theeffects of inhaled olprinone, a newly developed phosphodiesteraseIII inhibitor, on the contractility of fatigued diaphragm indogs. Methods. Diaphragmatic fatigue was induced by intermittent supramaximalbilateral electrophrenic stimulation at a frequency of 20 Hzstimulation applied for 30 min. When fatigue was established,group I (n=8) received inhaled vehicle; group II (n=8) receivedinhaled olprinone 1 mg; group III (n=8) received inhaled olprinone2 mg. Diaphragmatic contractility was assessed by transdiaphragmaticpressure (Pdi, cm H₂O). Results. In the presence of fatigue, in each group, Pdi at low-frequency(20 Hz) stimulation decreased from baseline values (P<0.05),whereas Pdi at high-frequency (100 Hz) stimulation did not change.In groups II and III, during olprinone administration, Pdi atboth stimuli increased from fatigued values (20 Hz stimulation:group II (mean (SD)) 10.8 (1.0) to 12.5 (1.3), group III 10.9(1.7) to 15.0 (3.0); 100 Hz stimulation: group II 20.1 (1.9)to 22.6 (1.3), group III 20.6 (2.0) to 24.5 (2.0), P<0.05).The increase in Pdi was larger in group III than in group II(P<0.05). Conclusions. Inhaled olprinone produces a dose-dependent improvementin contractility of fatigued canine diaphragm. Br J Anaesth 2002; 88: 408–11