Arterial and venous blood gas analyses during retrograde cerebral perfusion

OBJECTIVE: To examine arterial and venous blood gas analyses during retrograde cerebral perfusion to quantify oxygen uptake and carbon dioxide production. DESIGN: Prospective. SETTING: Community hospital, university setting, single institution. PARTICIPANTS: Twelve patients undergoing reconstructive aortic surgery with profound hypothermic circulatory arrest and retrograde cerebral perfusion. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: After 10 minutes of retrograde cerebral perfusion, blood gas analysis (measured at 37 degrees C, without temperature correction) was performed on blood samples drawn simultaneously from the arterial inflow and venous return (collected via aortic arch vessels) sites. Compared with arterial blood samples, PO2 (deltaPO2: 431.2+/-154.9 mm Hg; p<0.05), pH (deltapH: 0.16+/-0.09, p<0.05) and base excess (deltaBE: 1.0+/-0.85; p<0.05) decreased in venous blood samples, whereas PCO2 increased (deltaPCO2: 18.2+/-8.8 mm Hg; p<0.05). An arteriovenous content difference of 2.5+/-1.9 mL/dL reflected a total oxygen extraction of 20.5%+/-15.7%, although most extraction occurred from oxygen in solution. CONCLUSION: These findings suggest that retrograde cerebral perfusion produces cerebral aerobic metabolism.