The Role of Theophylline

Dr Richard H. T Edwards: I will deal first with respiratory muscle fatigue before coming to talk about weakness, from which fatigue must be distinguished. Table 1’ is a summary of the different types of fatigue, based on what can be demonstrated both in isolated muscle preparations and in man. This sequence should be the basis for thinking about drug strategies aimed at reversing fatigue in respiratory muscles.2 There are many different steps in the chain of command that may produce loss of force in a muscular contraction. These can be graphically represented by what can be called the catastrophe theory of muscle fatigue (Fig 1), which is one method of describing the delicate balance among loss of force, energy depletion, and reduction in excitation or activation of the muscle.3 This figure is not to suggest that fatigue is a catastrophe, although, of course, it may be in the case of respiratory muscles,