Monitoring Diaphragmatic Function

The diaphragm is the main respiratory muscle. Its contractile function can be adversely affected by several mechanisms including infection, surgery, trauma, nutritional deficiencies, metabolic derangements, and prolonged mechanical ventilation. Monitoring of diaphragmatic motion and contractile force can be used to estimate respiratory function and also to identify patients at risk of developing acute postoperative respiratory distress and predicting weaning failure. Unfortunately, clinical monitoring is currently poor in this field and neither sensitive nor specific. Several technical challenges remain to be overcome, with regard to pressure assessments and electrical measurements of muscle activity. Imaging evaluation using CT and ultrasound of the diaphragm wall motion and size is currently under investigation. The future will likely combine ultrasound evaluation of diaphragm motion and thickness along with a simultaneous evaluation of the electrical activity of the diaphragm in order to clinically monitor respiratory function in real time.