Why supine with head of the bed flat is an optimal position for breathing in a patient with C5 SCI, ASIA-A? The book says that supine holds the abdominal contents under diaphragm to improve zone of apposition and height of diaphragm dome. I think, this position hinders diaphragm to contract and thus decrease efficiency during inspiration. Whereas, I feel the Semi-Fowler’s position should be better for this patient, as it helps in inspiration better, while expiration is passive. Please explain.

A spinal cord injury at the level of C5 would indicate that the diaphragm is denervated.

The Semi-Fowler position means that gravity pulls the diaphragm walls downwards which in turn compresses the abdominal contents making inhalation difficult (if not near impossible for an SCI patient with such a high vertebral lesion). So, the literature is indeed correct that the supine position holds the abdominal contents under diaphragm to improve the zone of apposition and the height of the diaphragm dome – in other words, for this patient in the supine position, the diaphragm is in the high dome position thus enhancing inspiration and overall respiration.