Effect of lidocaine on improving cerebral protection provided by retrograde cerebral perfusion: a neuropathologic study

Prophylactic effect of intravenous lidocaine against cognitive deficit after cardiac surgery: A PRISMA-compliant meta-analysis and trial sequential analysis

BACKGROUND

This study aimed at providing an updated evidence of the association between intraoperative lidocaine and risk of postcardiac surgery cognitive deficit.

METHODS

Randomized clinical trials (RCTs) investigating effects of intravenous lidocaine against cognitive deficit in adults undergoing cardiac surgeries were retrieved from the EMBASE, MEDLINE, Google scholar, and Cochrane controlled trials register databases from inception till May 2021. Risk of cognitive deficit was the primary endpoint, while secondary endpoints were length of stay (LOS) in intensive care unit/hospital. Impact of individual studies and cumulative evidence reliability were evaluated with sensitivity analyses and trial sequential analysis, respectively.

RESULTS

Six RCTs involving 963 patients published from 1999 to 2019 were included. In early postoperative period (i.e., 2 weeks), the use of intravenous lidocaine (overall incidence = 14.8%) was associated with a lower risk of cognitive deficit compared to that with placebo (overall incidence = 33.1%) (relative risk = 0.49, 95% confidence interval: 0.32-0.75). However, sensitivity analysis and trial sequential analysis signified insufficient evidence to arrive at a firm conclusion. In the late postoperative period (i.e., 6-10 weeks), perioperative intravenous lidocaine (overall incidence = 37.9%) did not reduce the risk of cognitive deficit (relative risk = 0.99, 95% confidence interval: 0.84) compared to the placebo (overall incidence = 38.6%). Intravenous lidocaine was associated with a shortened LOS in intensive care unit/hospital with weak evidence.

CONCLUSION

Our results indicated a prophylactic effect of intravenous lidocaine against cognitive deficit only at the early postoperative period despite insufficient evidence. Further large-scale studies are warranted to assess its use for the prevention of cognitive deficit and enhancement of recovery (e.g., LOS).

Administration of lidocaine to prevent cognitive deficit in patients undergoing coronary artery bypass grafting and valve plasty: a systematic review and meta-analysis

INTRODUCTION

The administration of lidocaine to maintain cognitive function following coronary artery bypass grafting (CABG) and valve plasty is a controversial concept in terms of its effectiveness. We performed a systematic review to determine the effectiveness of treatment with lidocaine in preventing the occurrence of cognitive deficit after cardiac surgery. Area covered: To review the current literature on the subject, we searched the PubMed database and the Cochrane Library database (up to May 2015) and compiled a list of retrieved articles. Our final review includes only randomized controlled trials (RCTs) that compared lidocaine to a control (placebo) following CABG and valve plasty. Statistical analysis of the odds ratio (OR) and corresponding 95% confidence interval (CI) were used to determine the overall effectiveness of lidocaine for the prevention of cognitive deficit with both procedures. The Mantel-Haenszel method was used to pool data of the outcomes of cognitive deficit occurrence into fixed-effect model meta-analyses. Five RCTs were included in this study, with a total of 688 patients. Perioperative administration of lidocaine in patients undergoing cardiac surgery reduced occurrence of cognitive deficit (OR 0.583 [95% CI 0.438-0.777]; Z = -3.680; P = 0.00; I² = 52%). No significant difference in the early occurrence of cognitive deficit was revealed in patients after cardiac surgery (OR 0.909 [95% CI 0.600-1.376]; Z = -0.451; P = 0.652; I² = 11%). Expert commentary: Cognitive deficit associated with cardiac surgery is a common postoperative event. Lidocaine is contributed to a significantly reduced occurrence of cognitive deficit. Cognitive deficit management is recommended.

The effect of lidocaine on early postoperative cognitive dysfunction after coronary artery bypass surgery

We investigated the effect of lidocaine on the incidence of cognitive dysfunction in the early postoperative period after cardiac surgery. One-hundred-eighteen patients undergoing elective coronary artery bypass surgery with cardiopulmonary bypass (CPB) were randomized to receive either lidocaine (1.5 mg/kg bolus followed by a 4 mg/min infusion during operation and 4 mg/kg in the priming solution of CPB) or placebo. A battery of nine neuropsychological tests was administered before and 9 days after surgery. A postoperative deficit in any test was defined as a decline by more than or equal to the preoperative SD of that test in all patients. Any patient showing a deficit in two or more tests was defined as having postoperative cognitive dysfunction. Eighty-eight patients completed pre- and postoperative neuropsychological tests. Plasma lidocaine concentrations (microg/mL) were 4.78 +/- 0.52 (mean +/- SD), 5.38 +/- 0.95, 4.52 +/- 0.39, 5.82 +/- 0.76, and 7.10 +/- 1.09 at 10 min before CPB; 10, 30, and 60 min of CPB; and at the end of operation, respectively. The proportion of patients showing postoperative cognitive dysfunction was significantly reduced in the lidocaine group compared with that in the placebo group (18.6% versus 40.0%; P = 0.028). We conclude that intraoperative administration of lidocaine decreased the occurrence of cognitive dysfunction in the early postoperative period.

IMPLICATIONS

Postoperative cognitive dysfunction is a commonly recognized complication after cardiac surgery. Intraoperative cerebral microembolism and hypoperfusion have been proposed to be the major mechanisms. The results of this study show that intraoperative administration of lidocaine decreased the occurrence of early postoperative cognitive dysfunction, perhaps because of its neuroprotective effects.

Retrograde cerebral perfusion as a method of neuroprotection during thoracic aortic surgery

Retrograde cerebral perfusion is commonly used as an adjunct to hypothermic circulatory arrest to enhance cerebral protection during thoracic aortic surgery. This review summarizes a large number of studies that demonstrate a spectrum of beneficial, neutral, and detrimental effects of retrograde cerebral perfusion in humans and experimental animal models. It remains unclear whether retrograde cerebral perfusion provides effective cerebral perfusion, metabolic support, washout of embolic material, and improved neurological and neuropsychological outcome.

Neuroprotection with anaesthetic agents

The term 'neuroprotection' is used to refer to any prophylactic measure that is initiated during the peri-ischaemic period in order to improve neuronal survival. Cell death after ischaemia has an immediate, necrotic and a delayed, apoptotic origin. The major biochemical mechanisms that are involved in this process include transmembrane ionic fluxes and intracellular calcium increase, excitotoxicity, free radical formation, peroxynitrite production, release of inflammatory mediators, mitochondrial dysfunction, cytochrome c release, and activation of caspases and transcription factors. Strategies of neuroprotection essentially impact on those biochemical pathways. The label 'neuroprotectant' requires that the therapy has basic properties that are consistent with potential mechanisms of neuroprotection, and that conclusive results are available from animal studies that can be converted into clinical benefit. The present review focuses on neuroprotective effects of anaesthetics and is based on the most recently published reports.