Physician preference and, more recently, hospital protocol, generally dictate the choice of weaning, but certain other conditions may come into play as well. For example, patients who are extremely debilitated or have congestive heart failure or severe myopathy may fare better with a combination of synchronized intermittent mandatory ventilation and pressure support ventilation, which is less demanding on respiratory muscles.9 As a result, the increase in metabolic demand and venous blood flow that accompanies the transition from MV to spontaneous breathing is less likely to overwhelm the heart's ability to compensate in these patients.9 Here's a description of each method: