Ventilation and the critically ill parturient

Positive-pressure ventilation is the keystone in the management of pulmonary dysfunction in the critically ill. An increased understanding of both the benefits and hazards has led to a general consensus regarding the optimal techniques to ensure adequate gas exchange. Unfortunately, the same cannot be said for ventilation terminology which, due to a lack of standardization, lends itself to confusion. Pulmonary dysfunction in the parturient may arise from thoracic or extra-thoracic pathologies but both may be defined as acute lung injury. In its most severe form this constitutes acute respiratory distress syndrome. Acute lung injury results in reduced lung compliance and a marked decrease in the volume of functional lung. Ventilation strategies are now designed to recruit as much available lung tissue as possible while simultaneously minimizing the injurious effects of alveolar over-distension. Upon resolution of the underlying pathology mechanical ventilation may be withdrawn. Recent evidence suggests that this final stage need not be protracted, and if certain criteria are fulfilled, rapid weaning is feasible.