EXTRACORPOREAL CARBON-DIOXIDE REMOVAL TECHNIQUE IMPROVES OXYGENATION WITHOUT CAUSING OVERINFLATION

Extracorporeal CO2 removal combined with low frequency positive pressu re ventilation (ECCO(2)R-LFPPV) improves gas exchange and decreases pe ak pressures, respiratory rates, and tidal volumes in animals and in h umans. Recent evidence suggests that pulmonary barotrauma results from lung overinflation rather than from high pressures. This study was to test the hypothesis whether ECCO(2)R-LFPPV could improve gas exchange without causing lung overinflation, despite the use of higher levels of PEEP, when compared with conventional mechanical ventilation. Eleve n patients with severe adult respiratory distress syndrome (ARDS) who failed to respond to different modes of mechanical ventilation were tr eated with ECCO(2)R-LFPPV. Risk of pulmonary barotrauma was evaluated by static pressure-volume (P-V) curves and dynamic changes in volumes monitored by respiratory inductive plethysmography (Respitrace). ECCO( 2)R-LFPPV Pa-O2/Fl(O2) increased from 79 +/- 21 to 207 +/- 108 (p = 0. 003). Risk of barotrauma, as shown by the shape of the P-V curve, was present in all patients receiving mechanical ventilation even though m ost of them were treated with permissive hypoventilation. By contrast, no evidence of persistent lung overinflation could be detected by eit her static P-V curves or dynamic measurements in nine of 11 patients w ho were treated by ECCO(2)R-LFPPV. The two remaining patients had seve re airway obstruction because of bleeding, and they remained ventilate d with persistent risk of barotrauma. We conclude that ECCO(2)R-LFPPV improves gas exchange without causing lung overinflation in a majority of patients with ARDS.