Electromyographic registration of diaphragmatic fatigue during sustained trunk flexion in cervical cord injured patients

When performing forward trunk flexion, cervical cord injured (CCI) patients exhibit continuous and high EMG activity in the diaphragm and elevated abdominal pressures. This study addressed the question whether the trunk flexion manoeuvres cause such a high force development in the diaphragm that this muscle shows EMG signs of fatigue. Six patients with complete cervical cord lesions were tested sitting in their own wheelchairs. The tension-time indices obtained when patients were sitting in a relaxed position were moderately to markedly higher than in normal subjects. The force developed during trunk flexion averaged 30% of the maximal transdiaphragmatic pressure and was accompanied by clear EMG findings of diaphragmatic fatigue in all patients except one. The acute diaphragmatic load in certain CCI patients may well produce ischaemia and increase the risk of tissue impairment. Therefore, there appears to be a need for differing strategies in the short and in the long term treatment of CCI patients; longitudinal evaluation of main diaphragmatic function may be useful for an adequate amount of respiratory muscle training.