ОПРЕДЕЛЕНИЕ И ВСТУПЛЕНИЕ ПО ПРОБЛЕМЕ ПАРЕЗОВ И ПАРАЛИЧЕЙ ДИАФРАГМЫ
The diaphragm is the principal inspiratory muscle. The diaphragm descends with contraction, which leads to increased thoracic volume, negative intrathoracic pressure, and air entry into the lungs. The diaphragm is responsible for about two thirds of the tidal volume during tidal breathing.1 Diaphragmatic paresis is characterized by decreased strength of the muscle, while diaphragmatic paralysis is extreme muscle weakness such that no force of contraction is detectable. Diaphragmatic paresis and paralysis may be unilateral or bilateral. Diaphragmatic weakness may be caused by any lesion along the neuromuscular axis, including motor neurons of the spinal cord, the phrenic nerve, the neuromuscular junctions, and of the muscle itself. Unilateral diaphragmatic paresis or paralysis is often asymptomatic. However, bilateral diaphragmatic paralysis can lead to dyspnea on exertion, orthopnea, and even respiratory failure, particularly if other respiratory muscles are weak or if there is an underlying lung disease. Diaphragmatic weakness might be suggested by radiographic findings or the results of pulmonary function tests, but the diagnosis must be confirmed by a fluoroscopic sniff test, measurement of the transdiaphragmatic pressure, or electromyography (EMG) and nerve conduction studies. Treatment options include positive pressure ventilation, phrenic nerve pacing, and diaphragmatic plication.
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