Arterio venous carbon dioxide removal (AVCO/sub 2/R) for severe respiratory failure

Arteriovenous carbon dioxide removal (AVCO/sub 2/R) by a low-resistance gas exchanger in a simple arteriovenous shunt is capable of achieving near total CO/sub 2/ removal and lung rest during acute respiratory distress syndrome (ARDS). We evaluated AVCO/sub 2/R effect on a LD/sub 50/ smoke/burn (36 breath, 40% III/spl deg/ TBSA) ARDS model in a prospective, randomized, controlled, unblinded 7-day outcomes study of ventilator free days and survival. All AVCO/sub 2/R sheep survived, while only 2 SHAM animals survived the 7-day study. AVCO/sub 2/R had 2.4 ventilator dependent days versus 6.5 days with SHAM. For our initial patient experience, 5 adults in unresponsive, severe ARDS were successfully cannulated for AVCO/sub 2/R at bedside and completed the 72-h trial and 3/5 patients were discharged. AVCO/sub 2/R removed approximately 70% of CO/sub 2/. Changes in ventilator parameters from baseline to 48 h included a decrease in tidal volume, peak inspiratory pressure, minute ventilation, and respiratory rate. Next, a before-after study of AVCO/sub 2/R was performed on 8 subjects with ARDS. PaCO/sub 2/ decreased significantly despite a decrease in minute ventilation from baseline and normalization of pH. We propose the normalization of CO/sub 2/ and decreased minute ventilation allows amelioration of the pathophysiology of ARDS.