Carbon dioxide removal device: how long is long enough?

In 1969 Kolobow and coworkers [2] described use of VVCO2R in healthy sheep for 1 week, and they later demonstrated improved survival in injured sheep [3]. Clinical trials, however, failed to show improved outcomes [4]. Arteriovenous carbon dioxide removal (AVCO2R), as a simple arteriovenous shunt, eliminates several circuit components. AVCO2R removes near total carbon dioxide production with only 1 l/min (approximately 15% of cardiac output) blood flow and appears to be effective in acute respiratory distress disorder (ARDS), as shown in prospective randomized large animal and preliminary clinical trials. Our sheep model of severe ARDS is based on a third degree burn to 40% of the total body surface area and 48-breath smoke inhalation injury [5]. Because the median duration of AVCO2R treatment for ARDS is 4.8 days, our model allows comparison of ventilatory techniques over 5 days to evaluate pathophysiology and outcomes [6].