Pharmacological Cerebral Protection in Cardiac Surgery: An Update

Abstract

Aim of review:Postoperative cognitive dysfunction (POCD) remains a major issue in cardiovascular surgery, although advances have been made in anesthesia, surgery and neuroprotective measures. Pharmacological prevention and management of POCD has achieved some progress over the last one to two decades, yet no consensus or guideline being established. Method:The following key words in PubMed were searched: cerebral protection, brain protection, cardiac surgery, and postoperative cognitive decline, etc. Recent articles and literatures were searched and reviewed on the risk factors for POCD and the cerebral protective effects of pharmacological agents, in order to make a comprehensive review and offer an update. Recent findings: Risk factors for POCD reported in literatures include older age, male gender, cardiopulmonary bypass (CPB) use, cerebral embolization, pre-existing cognitive disturbance and genetic predisposition. The pharmacological agents with potential neuroprotective effects include volatile anesthetics, intravenous anesthetic agents, steroids, N-methyl-D -aspartate (NMDA) antagonists, nitric oxide carriers and some traditional Chinese herbal medicine such as gastrodin. Cerebral protection in current practice is achieved by a combination of different strategies including surgical (cerebral perfusion during CPB, aortic filter, carotid stents, avoidance of aortic atheroma) and nonsurgical measures (hypothermia, lumbar drain, management of mean arterial pressure, central venous pressure, cerebral perfusion pressure, pre-and postconditioning, and cerebral regional oxygenation monitoring, etc). Summary: Multiple factors are associated with the incidence of POCD. Numerous pharmacological agents have been found to have certain degree of neuroprotective effects. Large-scale, randomized, multicenter clinical trials will be needed for the integration of these agents into our clinical practice. ABSTRACT

Enhanced Recovery Pathways for Cardiac Surgery

“…Insulin resistance and increased glucose production are an additional concern as a result of the hormonal changes [6]. This pro-inflammatory process is particularly important for cardiac surgery because of the inflammation-inducing nature of cardiopulmonary bypass (CPB) [9]. In fact, CPB produces an immune response similar to what occurs in sepsis or systemic inflammatory response syndrome [7].…”

“…In fact, carbohydrate intake has been shown to decrease postoperative insulin resistance, surgical site infections, total number of complications, hospital length of stay, and hasten the return of bowel function [12,13]. Most protocols recommend a form of glucose-rich drink 2-3 h prior to surgery and some also recommend a carbohydrate drink the night before surgery [10,14]. Clearfast, Powerade, and Gatorade are common choices for most ERAS programs.…”

“…Making the best choice will usually depend upon information gathered from invasive monitors, institutional tradition, and physicians' clinical judgment. See Table 1 for a summary of the effects of specific vasoactive drugs [9,31,36]. Maintaining relatively stable hemodynamic parameters (≤ 20% deviation from the baseline) is critical for the success of ERAS protocol and patients' clinical outcomes [37].…”

“…Colloids are more costly than colloids, and colloids have not been shown any benefit in perioperative morbidity. Ultimately, the decision to administer intravenous fluids requires comprehensive clinical judgment [9,25].…”

Neuroprotection against stroke and encephalopathy after cardiac surgery

“…The variability in expected outcomes of volatile anesthetics use is a result of confusion surrounding their anesthetic mechanisms [19]. Volatile anesthetics can ideally provide neuroprotective effects through increased intracellular calcium, increased cerebral blood flow, downregulation of metabolism, excitotoxicity inhibition, reduction of oxidative stress, and increased potassium channel activity, although there is uncertainty about which agents are optimal and how dose dependent their effects are [19][20][21]. Overall, meta-analyses comparing isoflurane versus sevoflurane determined volatile anesthetic choice that does not affect postoperative outcomes for cardiac surgery patients [22].…”