The correlation between peri-operative hyperglycemia and mortality in cardiac surgery patients: A systematic review

Background: Hyperglycemia occurs frequently in patients undergoing cardiac surgery. It has been identified as a risk factor for increased peri-operative morbidity and mortality. Aim: To review the evidence of the correlation of peri-operative hyperglycemia with mortality in cardiac surgery patients and to discuss the main results in order to provide evidence-based knowledge for the appropriate glycemic control. Methods: We searched the electronic databases MEDLINE, CINAHL and EMBASE in June 2010. The material of our study was articles published between 1 January 1990 and 31 May 2010, which investigated the correlation between perioperative hyperglycemia and in-hospital and/or 30-day cardiac surgery mortality. Results: Out of the 16 reviewed articles in our study, 12 (75%) significantly associated hyperglycemia and inadequate blood glucose control with increased mortality. In addition, four of the reviewed articles were controlled randomized trials and among them only one demonstrated strong correlation between poor glycemic control and mortality. No study was multi-centre and the reviewed articles were characterized by different definitions of peri-operative hyperglycemia, different intensity and duration of the applied therapy and heterogeneity of the population. Conclusion: It is clear that peri-operative hyperglycemia is harmful for cardiac surgery patients. The significant shortage of randomized controlled trials, the absence of multicentre studies, the different definitions of peri-operative hyperglycemia, the different intensity and duration of the applied insulin therapy protocol and the heterogeneity of the studied population (diabetics and non-diabetics) are significant limitations, which could explain the inconsistent findings of the literature. These limitations indicate the need for further research. © The European Society of Cardiology 2012

Blood flow measurements within optic nerve head during on-pump cardiovascular operations. A window to the brain?

This observational study is conducted to demonstrate optic nerve head (ONH) blood flow alterations during extracorporeal circulation (ECC) in routine on-pump cardiovascular operations in order to evaluate the perfusion status of important autoregulatory tissue vascular beds during moderate hypothermia. Twenty-one patients free from eye disease were prospectively enrolled in our database. Perioperative ONH blood flow measurements were performed using a hand-held portable ocular laser Doppler flowmeter just after administration of general anesthesia and during cardiopulmonary bypass (CPB) upon the lowest temperature point of moderate hypothermia. Important operative flow variables were correlated to optic nerve blood flow during surgical phases. Statistical analysis showed significant reduction of 32.1 +/- 14.5% of mean ONH blood flow in phase 2 (P<0.0001) compared to the reference flow values of phase 1. A negative univariate association between ECC time and ONH blood flow in phase 2 (P=0.031) is noted. This angiokinetic approach can detect changes of flow within autoregulatory vascular tissue beds like ONH, thus creating a 'window' on cerebral microvasculature. ONH blood flow is reduced during CPB. Our data suggest that it is of paramount importance to avoid extracorporeal prolongation even in moderate hypothermic cardiovascular operations. (C) 2011 Published by European Association for Cardio-Thoracic Surgery. All rights reserved