Pathophysiology of respiratory muscles in course of undernutrition.

Derangements of respiratory muscle function play a key role in the pathogenesis of respiratory failure, as they are able to determine respiratory pump failure and ventilatory insufficiency. Undernutrition negatively influences respiratory muscle function both directly through loss of contractile elements, and indirectly, through worsening or induction of muscle composition derangements. The present review focuses on the importance of undernutrition as a pathogenetic factor of altered respiratory muscle function: respiratory muscle structure and function derangements in both animal models of undernutrition and in undernourished subjects without lung disease are described. The pathophysiology of respiratory muscles in undernourished patients with lung disease is also discussed, along with the complex relationships between undernutrition and some other "metabolic" factors of ventilatory insufficiency.