咖啡因对膈肌收缩力及膈肌疲劳的影响

本文用21只实验犬探讨了咖啡因对正常及疲劳后膈肌收缩功能的影响,探讨了可能的机理。用双气囊导管-差分换能器系统测定跨膈压-刺激频率(Pdi-F)曲线,以 Pdi-F 曲线作为评价膈肌收缩力的指标。膈肌疲劳模型用连续电刺激两侧膈神经的方法制备。结果表明,无论是在正常或疲劳后膈肌,咖啡因(20mg/kg)均可显著地增强其收缩力。而且,咖啡因对膈肌的正性肌力作用与心输出量、肺总阻力及动态肺顺应性变化无关。指出咖啡因在治疗慢阻肺呼吸肌疲劳方面可能有一定的临床价值。

Effect of caffeine on diaphragmatic contractility and fatigue

We investigated the effect of caffeine on diaphragmatic contractility and fatigue in 21 dogs. Diaphragmatic contractility was assessed by measuring transdiaphragmatie pressure (Pdi) during supermaximal stimulation of the phrenie nerves at different frequencies,and Pdi was measured with a pair of balloons.In protocol 1,the effect of caffeine on contractility of non-fatigued diaphragm was studied in 7 dogs.Caffeine infusion increased Pdi significantly at all frequencies of stimulation.In protocol 2,diaphragmatic fatigue was induced by electrophrenic stimulation (30 Hz,duty cycle 1.0,30 min).The recovery profile after fatigue run was observed in 5 dogs.In another group of 9 dogs,caffeine was infused during stable fatigue peroid and Pdi increased significantly at all frequencies of stimulation after caffeine infusion.The increase in Pdi was not due to changes in cardiac output or lung mechanics (Cdyn and Rtot),neither of which changed significantly after caffeine infusion.We conclude that caffeine improves muscle contractility both in non-fatigued and fatigued diaphragm in dogs.