Arterio venous carbon dioxide removal (AVCO₂R) for severe respiratory failure

Arteriovenous carbon dioxide removal (AVCO₂R) by a low-resistance gas exchanger in a simple arteriovenous shunt is capable of achieving near total CO₂ removal and lung rest during ARDS. We evaluated AVCO₂R effect on a LD₅₀ smoke/burn (36 breath, 40% III° TBSA) ARDS model in a prospective, randomized, controlled, unblinded 7-day outcomes study of ventilator free days and survival. All AVCO₂R sheep survived, while only 2 SHAM animals survived the 7-day study. AVCO₂R had 2.4 ventilator dependent days versus 6.5 days with SHAM. Four our initial patient experience, 5 adults in unresponsive, severe ARDS were successfully cannulated for AVCO₂R at bedside and completed the 72-h trial and 3/5 patients were discharged. AVCO₂R removed approximately 70% of CO₂. 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 AVCO₂R was performed on 8 subjects with ARDS. PaCO₂ decreased significantly despite a decrease in minute ventilation from baseline and normalization of pH. We propose the normalization of CO₂ and decreased minute ventilation allows amelioration of the pathophysiology of ARDS.