Difficult Weaning From Mechanical Ventilation And The Role Of Noninvasive Ventilation

Abstract

Mechanical ventilation refers to any method of breathing in which a mechanical apparatus is used to maintain adequate gas exchange. It is indicatd when the patient’s spontaneous ventilation is not adequate to sustain life or when it is necessary to take control of the patient’s ventilation to prevent impending collapse of the organ functions. Although mechanical ventilation could be life saving it is also associated with numerous complications. The incidence of some complications increases with duration of mechanical ventilation. This together with the observation that complications increase the length of stay, increase mortality, and increase costs provides a compelling rationale for efforts to reduce the duration of mechanical ventilation. Weaning from mechanical ventilation can be defined as the process of abruptly or gradually withdrawing ventilator support. This is usually simple in patients with known good pulmonary functions prior to an acute reversible event. It is not simple in patients recovering from a prolonged ventilatory support . Determining when a patient is ready to wean continue to be a concern of clinicians and invistigators. Premature attempts of weaning and extubtion can be deleterious to patient physilogic and psychological well being. Weaning indiced are objective criteria that are used to predict the readiness of patients to maintain spontaneous breathing .Despite the popularity of many of these predictors, Littile evidence indicates that they are in fact predictive. In general, they are good negative predictors but poor positive predictors. A significant number of patients will experience prolonged weaning failure despite multiple weaning attempts following SBTs. Assuming that reversible factors have been optimized (e.g. Cardiac, metabolic, ...etc ), the eventual clinical outcome of patients with prolonged weaning failure will depend on the long term trajectory of the underlying disease. A significant number of patients with prolonged weaning failure remain ventilator dependant, requiring long-term ventilatory support, which may now be provided as NIV in the home setting.

In patients with persistent weaning failure, earlier extubation with NIV can decrease the duration of ventilatory support, length of hospital stay, incidence of nosocomial pneumonia and septic shock, and improved survival, compared with patients following conventional weaning approach.