ADRB2 gly16gly Genotype, Cardiac Output, and Cerebral Oxygenation in Patients Undergoing Anesthesia for Abdominal Aortic Aneurysm Surgery.

BACKGROUND: Gly16arg polymorphism of the adrenergic beta(2)-receptor is associated with the elevated cardiac output (Q) in healthy gly16-homozygotic subjects. We questioned whether this polymorphism also affects Q and regional cerebral oxygen saturation (Sco(2)) during anesthesia in vascular surgical patients. METHODS: One hundred sixty-eight patients (age 71 +/- 6 years) admitted for elective surgery were included. Cardiovascular variables were determined before and during anesthesia by intravascular pulse contour analysis (Nexfin) and Sco(2) by cerebral oximetry (INVOS 5100C). Genotyping was performed with the TaqMan assay. RESULTS: Before anesthesia, Q and Sco(2) were 4.7 +/- 1.2 L/min and 66% +/- 8%, respectively, and linearly correlated (r = 0.35, P<.0001). In patients with the gly16gly genotype baseline, Q was approximately 0.4 L/min greater than in arg16 carriers (CI95: 0.0-0.8, P-t test =.03), but during anesthesia, the difference was 0.3 L/min (Pmixed-model=.07). Post hoc analysis revealed the change in Sco(2) from baseline to the induction of anesthesia to be on average 2% greater in gly16gly homozygotes than in arg16 patients when adjusted for the change in Q (P =.03; CI95: 0.2-4.0%). CONCLUSIONS: This study suggests that the beta(2)-adrenoceptor gly16gly genotype is associated with the elevated resting Q. An interesting trend to greater frontal lobe oxygenation at induction of anesthesia in patients with gly16gly genotype was found, but because of insufficient sample size and lack of Pco(2) control throughout the measurements, the presented data may only serve as the hypothesis generating for future studies. The confidence limits indicate that the magnitude of the effects may range from clinically insignificant to potentially important.