Nutritional support in long term intensive care with special reference to ventilator patients: a review

Patients requiring long term intensive care and/or prolonged ventilatory support, are frequently undergoing progressive malnutrition, occasionally complicated by a hypercatabolic state. Sepsis, fever and the requirements for postoperative healing will add further nutritional demands on such patients. In contrast to starvation, critically ill patients maintained on protein-free energy-deficient diet do not adapt to utilization of their lipid to provide energy needs. Mobilization of endogenous fat stores is reduced, and this reduction leads to increased gluconeogenesis from amino acids derived from muscle protein to meet the increased energy needs. Low serum albumin, possible low surfactant production, devitalization of the alveolo-capillary membrane and impaired immunocompetence could contribute to the development of pulmonary transudation, alveolar collapse, low compliance and pulmonary infection. Such sequelae of a protein-free energy-deficient diet would delay weaning patients off prolonged mechanical ventilation. Nutritional assessment, which may be determined serially, and means of nutritional support are outlined.