PROLONGED HEMODYNAMIC STABILITY DURING ARTERIOVENOUS CARBON-DIOXIDE REMOVAL FOR SEVERE RESPIRATORY-FAILURE

Objective: The effects of prolonged arteriovenous carbon dioxide remov al on hemodynamics during severe respiratory failure were evaluated in adult sheep with severe smoke inhalation injury. Methods: Adult femal e sheep (n = 6, 33.8 +/- 5.2 kg) were subjected to intratracheal cotto n severe smoke insufflation to a mean carboxyhemoglobin level of 83% /- 3%. Twenty-four hours after injury, a low-resistance 2.5 m(2) membr ane oxygenator was placed in a carotid-to-jugular pumpless arterioveno us shunt at unrestricted flow to allow complete carbon dioxide removal and reductions in ventilator support. Animals remained conscious, and heart rate, cardiac output, mean arterial pressure, and pulmonary art erial pressure were measured at baseline, after injury, and daily duri ng support with the arteriovenous carbon dioxide removal circuit for 7 days. Results: All animals survived the study period. Carbon dioxide removal ranged from 99.7 +/- 13.7 to 152.2 +/- 16.2 ml/min, and five ( 83%) of the six animals were successfully weaned from the ventilator b efore day 7. During full support with the arteriovenous carbon dioxide removal circuit, shunt flow ranged from 1.24 +/- 0.06 to 1.43 +/- 0.0 8 L/min and accounted for 20.1% +/- 1.4% to 25.9% +/- 2.4% of cardiac output. No statistically significant changes in heart rate, cardiac ou tput, mean arterial pressure, or pulmonary artery pressure were demons trated over the study course despite the extracorporeal shunt flow. Co nclusions: Arteriovenous carbon dioxide removal as a simplified means of extracorporeal gas exchange support is relatively safe without adve rse hemodynamic effects or complications.