重症监护室患者呼吸肌肌力的评价

Evaluation of respiratory muscle strength for patients in the intensive care unit

ICU患者呼吸肌肌力的测定对预测撤机后的结局具有重要的作用 ,要求测定方法简便、精确 ,并适用于对危重患者呼吸肌疲劳 (RMW)的测定。肺活量测量是一种非特异性的、受主观影响、且相对不敏感的简便实用方法 ;最大呼吸压是用记录呼吸肌产生压力的大小来评价呼吸肌肌力的方法 ,它易于测定 ,但受主观因素影响。膈神经电刺激、膈神经磁刺激具有不受主观影响的优点 ,后者克服了前者的某些缺点 ,将来可能成为评估ICU患者膈肌肌力的一种无创性检查方法。在ICU ,患者RMW主要取决加载于呼吸肌泵的通气负荷 ,负荷 /能力比具有决定性作用。临床上脱机失败是因为相对于呼吸肌的能力呼吸负荷过重触发了“疲劳过程”。

The determination of respiratory muscle strength in the intensive care unit(ICU)plays a potential role in prediction of weaning outcome.An easy and accurate method would also allow investigation of respiratory muscle weakness(RMW)in critically ill patients.Vital capacity is a nonspecific,volitional and relatively insensitive method for the measurement of strength.The maximum respiratory pressures are easily measured by documenting the capacity of respiratory muscles to generate pressure.However,it also is a volitional test.Electrical phrenic nerve stimulation(EPNS) and magnetic phrenic nerve stimulation(MPNS) have the great advantages of being nonvolitional measures of diaphragm strength.Since it is less painful,MPNS is more acceptable than EPNS for patients,and the MPNS overcomes some of the difficulties encountered during EPNS.Therefore,the MPNS may become an important noninvasive method for evaluation of diaphragmatic strength in ICU in future.The RMW in the ICU depends on the ventilatory load imposed on the respiratory muscle pump.Clinically,weaning failure may be due to “fatiguing process” initiated in the excessively loaded respiratory muscles in relation to their capacity.