Effects of arterial hypoxia and beta-adrenoceptor blockade on cerebral blood flow and oxygen uptake following E. coli endotoxin in dogs

Delirium following vascular surgery: increased incidence with preoperative beta-blocker administration

PURPOSE

To determine if there is an association between perioperative administration of beta-blockers and postoperative delirium in patients undergoing vascular surgery.

METHODS

After Institutional Review Board approval, data were retrospectively collected on patients who underwent vascular surgery in an academic hospital during the period January 2006 to January 2007. Patients with preoperative altered level of consciousness, carotid endarterectomy, or discharge within 24 h of surgery were excluded from the study. Identification of delirium was based on evaluation of the level of consciousness with the NEECHAM Confusion Scale and/or a chart-based instrument for delirium. Multivariable logistic regression analysis was used to identify independent perioperative predictors of postoperative delirium. Beta-blockers were tested for a potential effect.

RESULTS

The incidence of postoperative delirium was 128/582 (22%). Independent predictors included age (OR 1.04, 95% CI [1.02-1.07]), history of cerebrovascular accident/transient ischemic attack (OR 2.64, 95% CI [1.57-4.55]), and depression (OR 3.56, 95% CI [1.53-8.28]). Open aortic reconstruction was associated with an OR of 5.34, 95% CI (2.54-11.2) and amputation with an OR of 4.66, 95% CI (1.96-11.09). Preoperative beta-blocker administration increased the odds of postoperative delirium 2.06 times (95% CI [1.18-3.6]). Statin administration reduced the odds of delirium by 44% (95% CI [0.37-0.88]). The model was reliable (Hosmer-Lemeshow test, P = 0.72) and discriminative (area under the receiver operating characteristic [ROC] curve = 0.729).

CONCLUSIONS

Preoperative administration of beta-blockers is associated with an increased risk of postoperative delirium after vascular surgery. Conversely, preoperative statin administration is associated with a lower risk of postoperative delirium. A randomized prospective controlled trial is required to validate these findings.

Localization of norepinephrine and serotonin transporter in mouse brain capillary endothelial cells

Monoamines function as a vasoactive modulator in the central nervous system (CNS) and are believed to regulate blood-brain barrier (BBB) function. Although monoamine transport is an essential process for regulating the extracellular monoamine concentration, the transport systems for monoamines at the BBB are poorly understood. mRNA expression of norepinephrine transporter (NET) and serotonin transporter (SERT) has been detected in a conditionally immortalized mouse brain capillary endothelial cell line (TM-BBB4) used as an in vitro model of the BBB, whereas no dopamine transporter (DAT) was detected. Western blot analysis showed the expression of NET and SERT protein in the membrane fraction of mouse brain capillaries and TM-BBB4 cells. Immunohistochemical analysis revealed that NET and SERT are localized at the brain capillaries in the mouse cerebral cortex, and suggests that NET is localized at the abluminal side of brain capillary endothelial cells, and SERT is localized at the luminal and abluminal sides. NET and SERT expressed at the BBB may be involved in the inactivation of monoamines released from neurons around the BBB.