Cardiopulmonary Bypass Management and Neurologic Outcomes: An Evidence-Based Appraisal of Current Practices

Abstract

Neurologic complications after cardiac surgery are of growing importance for an aging surgical population. In this review, we provide a critical appraisal of the impact of current cardiopulmonary bypass (CPB) management strategies on neurologic complications. Other than the use of 20-40 microm arterial line filters and membrane oxygenators, newer modifications of the basic CPB apparatus or the use of specialized equipment or procedures (including hypothermia and "tight" glucose control) have unproven benefit on neurologic outcomes. Epiaortic ultrasound can be considered for ascending aorta manipulations to avoid atheroma, although available clinical trials assessing this maneuver are limited. Current approaches for managing flow, arterial blood pressure, and pH during CPB are supported by data from clinical investigations, but these studies included few elderly or high-risk patients and predated many other contemporary practices. Although there are promising data on the benefits of some drugs blocking excitatory amino acid signaling pathways and inflammation, there are currently no drugs that can be recommended for neuroprotection during CPB. Together, the reviewed data highlight the deficiencies of the current knowledge base that physicians are dependent on to guide patient care during CPB. Multicenter clinical trials assessing measures to reduce the frequency of neurologic complications are needed to develop evidence-based strategies to avoid increasing patient morbidity and mortality.

Risks for Impaired Cerebral Autoregulation During Cardiopulmonary Bypass and Postoperative Stroke

“…11 Of particular concern is the potential for increased frequency of these complications, given the increasing proportion of surgical patients who are aged and have preexisting cerebral vascular disease. 12 13 Impaired CBF autoregulation might contribute to brain ischaemic injury when arterial pressure is low such as during CPB.…”

Effect of intravenous lidocaine on the transcerebral inflammatory response during cardiac surgery: a randomized-controlled trial

“…3,4 The mechanism(s) of POCD remains elusive, although several contributing factors have been proposed, 1 including the exacerbation of preoperative cognitive impairment, 5 genetic predisposition, cerebral embolism/hypoperfusion, hemodilution, hyperglycemia, anesthetic neurotoxicity, [6][7][8] and perioperative hyperthermia. 9 In addition to these mechanisms, cerebral inflammation in response to embolic and other events during CPB, manifested by transcerebral platelet activation, 10 has also been proposed as a mechanism linking POCD to cardiac surgery.…”

Value of Specialized Preanesthetic Clinic for Cardiac and Major Vascular Surgery Patients

“…These strategies can include carotid Doppler imaging and repair, if necessary; higher hematocrit and arterial blood pressure targets during cardiopulmonary bypass; use of epiaortic ultrasound scanning to avoid potential plaque dislodgement during aortic clamping; and near-infrared spectroscopy monitoring to optimize various intraoperative parameters. 26 Whether ''off'' versus ''on'' cardiopulmonary bypass surgery affects cognitive outcomes has been the subject of considerable debate. 27 If patients who are at risk of adverse neurologic outcomes are identified in the PAC, preventive measures may be undertaken.…”