New approaches to the ventilatory management of the adult respiratory distress syndrome

A Pressure-Targeted Strategy for Ventilatory Management of the Adult Respiratory Distress Syndrome. Skeptics argue that none of the recently introduced approaches to the ventilatory management of ARDS has been proven unequivocally to be better than traditional management. In my view, however, the data currently available (although indirect) argue eloquently that alternatives to conventional ventilation strategies must be developed; the experimental evidence of pressure-induced lung injury is simply too compelling to ignore (Table 4). The scant epidemiologic data available, although hardly definitive, support the adoption of a less aggressive approach to ventilation and new target values for blood gases .^50,52 Pathologic, physiologic, and theoretical arguments strongly favor a strategy that attempts to control alveolar pressure, not arterial PCO₂. The repeated use of tidal volumes and pressures greater than the lung was designed to sustain should be avoided; tidal transalveolar pressures should be limited to 35 cm H₂O or less. At the same time, end-expiratory alveolar pressure, the sum of PEEP plus auto-PEEP, must be sufficient to avoid end-tidal collapse of alveolar units (approximately 7 to 15 cm H₂O). The oxygen demands of the patient with ARDS should be minimized to lower the needs for ventilation and pressure, and the least mean alveolar pressure necessary to accomplish unequivocal therapeutic goals should be used. Once adequate end-expiratory alveolar pressure has been assured, any increases of mean airway pressure that are intended to raise arterial oxygen saturation should be made by extending the inspiratory time fraction, not by raising PEEP further. Finally, when permissive hypercapnia is considered inadvisable or the necessary level of hypercapnia seems too extreme, consideration should be given to adjunctive measures of removing carbon dioxide rather than to the application of alveolar pressures that would put the lung at risk for further damage.