Cardiac troponins and volatile anaesthetics in coronary artery bypass graft surgery: A systematic review, meta-analysis and trial sequential analysis.

BACKGROUND: Reports from animal studies indicate that volatile anaesthetics protect the myocardium against the effects of acute ischaemia-reperfusion injury by reducing infarct size. This cardioprotective effect in the clinical setting of coronary artery bypass graft (CABG) surgery, where the heart is subjected to global ischaemia-reperfusion injury, remains controversial. OBJECTIVE: The objective was to demonstrate that clinical studies investigating the cardioprotective effect of volatile anaesthetics on cardiac troponins in CABG are no longer warranted. We also investigated the effect of volatile anaesthetics on cardiac enzymes in off-pump cardiac surgery. DESIGN: Systematic review of randomised clinical trials, meta-analyses and trial sequential analysis (TSA). DATA SOURCES: Trials between January 1985 and March 2015 were obtained from electronic databases (Medline, Excerpta Medica Database (EMBASE), Cochrane Controlled Trial Register, abstracts from major anaesthesiology and cardiology journals and reference lists of relevant randomised trials and review articles. ELIGIBILITY CRITERIA: Relevant randomised clinical trials were included. We investigated the effect of volatile anaesthetics in both off-pump and on-pump CABG surgery with respect to troponin release [peak postoperative cardiac troponin I (cTnI) and cardiac troponin T (cTnT), cTnI/cTnT] and performed two separate meta-analyses. TSA was used to overcome the weakness of a type-1 error associated with repeated meta-analyses. RESULTS: From 30 studies, 2578 patients were pooled for the meta-analysis. The outcome significantly favours the use of peroperative volatile over non-volatile anaesthetics during on-pump CABG surgery with regard to peak postoperative cTnI (0.995 mg l; standard mean difference, 95% confidence interval, -1.316 to -0.673; P < 0.001). Meta-analysis of 11 off-pump studies showed no difference in peak postoperative cTnI (0.385 mg l; standard mean difference, 95% confidence interval, -0.857 to 0.087; P = 0.11). TSA indicated that the required information size for on-pump surgery was 1072 patients, and for off-pump surgery it was 1442; this latter figure has not yet been reached. CONCLUSION: Studies investigating the cardioprotective effect of volatile anaesthetics on cardiac troponins in on-pump CABG surgery are no longer warranted. This is not yet the case for off-pump surgery.

Reverse Trendelenburg position reduces intracranial pressure during craniotomy.

Cerebral swelling and herniation pose serious surgical obstacles during craniotomy for space-occupying lesions. Positioning patients head-up has been shown previously to reduce intracranial pressure (ICP) in neurotraumatized patients, but has not been investigated during intracranial surgery. The current study examined the effects of 10-deg reverse Trendelenburg position (RTP) on ICP and cerebral perfusion pressure (CPP). Forty adult patients subjected to craniotomy for supratentorial tumors were given standardized propofol-fentanyl-cisatracurium general anesthesia and were moderately hyperventilated. In 26 of 40 patients with expected poor clinical outcome, an additional catheter was placed in the internal jugular bulb to determine internal jugular bulb pressure (JBP). ICP was determined by subdural measurement using a 22-gauge needle advanced through the dura after removal of the bone flap. ICP was referenced to the level of the dural incision. ICP, mean arterial blood pressure, and CPP were compared with repeat measurements 1 minute after RTP. The tension of the dura was graded qualitatively by the surgeon by digital palpation and was compared to post-RTP. ICP decreased from 9.5 mm Hg to 6.0 mm Hg ( P <.001; all values are median) within 1 minute after 10-deg RTP. Mean arterial blood pressure decreased from 82.0 mm Hg to 78.5 mm Hg ( P <.001). CPP was unchanged (70.5 mm Hg versus 71 mm Hg after RTP), whereas JBP decreased from 8 mm Hg to 4 mm Hg ( P <.001). High initial ICP was correlated to the greatest magnitude of decrease in ICP. No significant correlation was found between change in ICP and change in JBP. Intracranial pressure after RTP resulted in decreased tension of the dura. RTP appears to be an effective means of reducing ICP during craniotomy, thereby reducing the risk of cerebral herniation. CPP is not affected. Studies over longer periods of time are warranted, however.