Weaning from the ventilator in patients with respiratory failure

textabstractWeaning from the ventilator is the gradual withdrawal of mechanical ventilatory support. Mechanical ventilation is well-accepted as rescue therapy in patients with life-threatening respiratory failure. As this treatment is associated with substantial morbidity and mortality, ventilatory support is only considered beneficial when applied during a limited period. In many patients however weaning from the ventilator is a cumbersome process. In this chapter the issues related to the weaning process will be discussed. Firstly, the cardio-pulmonary diseases present before the acute respiratory failure necessitating ventilatory support, will be reviewed with emphasis on respiratory function before the critical illness. The nutritional status of the patients will be discussed, as this is known to affect the clinical course during ventilatory support and weaning. Secondly, the conditions leading to the institution of mechanical ventilation will be discussed with emphasis on the pathophysiology of the acute respiratory failure. The effects of mechanical ventilation on respiratory muscle function as well as the effects of critical illness on body composition will be considered. Finally, factors related to the withdrawal of ventilatory support as respiratory load and neuromuscular function will be elucidated