QUANTITATIVE EVALUATION OF INSPIRATORY EFFORT AND ITS REDUCTION.

我们研究了11只杂种犬横膈膜肌张力与横膈膜压差的关系。[方法]在颈部暴露膈神经并进行刺激（20赫兹和50赫兹的破伤风刺激），通过附着在膈下表面的换能器测量双侧膈肌张力。在食管和胃内分别插入2根球囊导管，测量并计算压力差。我们通过减少膈神经的刺激来控制膈肌收缩，并研究膈肌收缩与横膈膜压差的关系。然后继续以15/ min的速率对膈神经进行强直刺激30 min。[结果]膈肌张力降低的同时，压差也减小，但经膈压差减小的程度始终小于肌张力减小的程度。在30分钟的最大刺激期间，肌肉张力和横膈膜压差随时间下降。肌张力下降较快，但横膈膜压差下降较慢，两参数出现不一致。【讨论】横膈膜压差被认为是吸气力的一个指标，但横膈膜肌张力和横膈膜压差之间存在差异。当使用横膈膜压力差来估计吸气力时，有可能低估膈肌疲劳。[结论]膈肌张力与横膈膜压差之间存在差异。当使用横膈膜压差作为吸气努力的指标时，吸气努力和肌肉疲劳可能被低估。

WE INVESTIGATED THE RELATIONSHIP BETWEEN DIAPHRAGMATIC MUSCLE TENSION AND TRANSDIAPHRAGMATIC PRESSURE DIFFERENCE IN ELEVEN MONGREL DOGS.[METHOD]PHRENIC NERVES WERE EXPOSED AND STIMULATED AT NECK REGION (TETANUS STIMULATION FOR ISEC AT 20Hz AND 50Hz), AND BILATERAL DIAPHRAGMATIC MUSCLE TENSIONS WERE MEASURED THROUGH TRANSDUCERS ATTACHED TO INFRADIAPHRAGMATIC SURFACE.TWO BALOON-CATHETERS WERE INSERTED TO ESHOPHAGUS AND STOMACH,THEN THE PRESSURE DIFFERENCES WERE MEASURED AND CALUCULATED.WE CONTROLLED THE DIAPHARAGMATIC CONTRACTION BY REDUCING THE STIMULI TO PHRENIC NERVE,AND INVESTIGATED THE RELATIONSHIP BETWEEN CONTRACTION AND TRANSDIAPHRAGMATIC PRESSURE DIFFERENCES.THEN WE CONTINUED TO STIMULATE THE PHRENIC NERVES BY TETANIC STIMULI FOR 30 MIN AT A RATE OF 15/MIN.[RESULTS] THOUGH REDUCING THE DIAPHRAGMATIC MUSCLE TENSION,PRESSURE DIFFERENCE ALSO DECREASED,THE EXTENT OF DECREASE WERE ALWAYS SMALLER IN TRANSDIAPHRAGMATIC PRESSURE DIFFERENCE THAN THOSE IN MUSCLE TENSION.DURING 30 MIN SUPRAMAXIMAL STIMULATION,BOTH MUSCLE TENSION AND TRANSDIAPHRAGMATIC PRESSURE DIFFERENCE DECREASED WITH TIME.THOUGH THE MUSCLE TENSION DECREASED RAPIDLY,THE TRANSDIAPHRAGMATIC PRESSURE DEFFERENCE DECREASED SLOWLY,SO THE DESCREPANCY BETWEEN TWO PARAMETERS APPEARED.[DISCUSSION] TRANSDIAPHRAGMATIC PRESSURE DDIFFERENCE IS RECOGNIZED AS A INDICATOR OF INSPIRATORY EFFORT,BUT THERE IS A DESCREPANCY BETWEEN THE DIAPHRAGMATIC MUSCLE TENSION AND TRANSDIAPHRAGMATIC PRESSURE DIFFERENCE.THERE IS A POSSIBILITY TO UNDERESTIMETE AN DIAPHRAGMATIC MUSCLE FATIGUE WHE THE TRANSDIAPHRAGMATIC PRESSURE DIFFERENCE IS USED FOR ESTIMATION OF INSPIRATORY EFFORT.[CONCLUSIONS]THERE IS A DESCREPANCY BETWEEN DIAPHRAGMATIC MUSCLE TENSION AND TRANSDIAPHRAGMATIC PRESSURE DIFFERENCE.INSPIRATORY EFFORT AND MUSCLE FATIGUE CAN BE UNDERESTIMATED WHEN THE TRANSDIAPHRAGMATIC PRESSURE DIFFERENCE IS USED AS AN INDICATOR OF INSPIRATORY EFFORT.