CLINICAL-ASSESSMENT OF THE RESPIRATORY MUSCLES

This review examines approaches to evaluation of the respiratory muscles and describes new techniques that may, be more quantitative, less effort dependent, and less invasive than conventional methods. To evaluate strength of the respiratory muscles, maximum inspiratory and expiratory pressures remain useful measures. Potential methodologic errors, however, necessitate careful technique. Evaluation of the twitch response to direct phrenic nerve stimulation may ultimately prove more quantitative and less effort dependent than measurements of maximum pressure. Many techniques are also available to measure endurance of respiratory muscles belt most are less than satisfactory outside the research environment because of poor reproducibility and other procedural difficulties. The maximum incremental resistive loading test, however; has pl oven to be practical and well tolerated. There is little substitute for careful clinical observation of respiratory muscle coordination and movement, particularly in the patient with suspected respiratory muscle weakness or chest wall distortion In conclusion, though the respiratory muscles are difficult to evaluate, techniques are available that can be quite helpful for assessment, particularly in response to interventions such as rehabilitation.