Postoperative Hyperthermia Is Associated With Cognitive Dysfunction After Coronary Artery Bypass Graft Surgery

Abstract

Background and Purpose-Temperature is a well-known modulator of experimental cerebral injury. We hypothesized that hyperthermia would be associated with a worsened cognitive outcome after coronary artery bypass graft surgery (CABG). Methods-Three hundred consenting patients undergoing cardiopulmonary bypass for CABG had hourly postoperative temperatures recorded. The degree of postoperative hyperthermia was determined by using the maximum temperature within the first 24 hours as well as by calculating the area under the curve for temperatures Ͼ37°C. Patients underwent a battery of cognitive testing both before surgery and 6 weeks after surgery. By use of factor analysis, 4 cognitive domains (scores) were identified, and the mean of the 4 scores was used to calculate the cognitive index (CI). Cognitive change was calculated as the 6-week CI minus the baseline CI. Multivariable linear regression (controlling for age, baseline cognitive function, and temperature during cardiopulmonary bypass) was used to compare postoperative hyperthermia with the postoperative cognitive change. Results-The maximum temperature within the first 24 hours after CABG ranged from 37.2°C to 39.3°C. There was no relationship between area under the curve for temperatures Ͼ37°C and cognitive dysfunction (Pϭ0.45). However, the maximum postoperative temperature was associated with a greater amount of cognitive dysfunction at 6 weeks (Pϭ0.05). Conclusions-This is the first report relating postoperative hyperthermia to cognitive dysfunction after cardiac surgery.Whether the hyperthermia caused the worsened outcome or whether processes that resulted in the worsened cognitive outcome also produced hyperthermia requires further investigation. In addition, interventions to avoid postoperative hyperthermia may be warranted to improve cerebral outcome after cardiac surgery. (Stroke. 2002;33:537-541.)

Predictors of Early Neurocognitive Deficits in Low-Risk Patients Undergoing On-Pump Coronary Artery Bypass Surgery

“…However, specific maneuvers performed during the surgical procedure, eg, manipulation of an atherosclerotic ascending aorta, prolonged cardiopulmonary bypass time, and cerebral hyperthermia have been associated with poorer neurologic outcome. 7,14,15 Most studies examining predictors of POCDs have identified both patient-related and surgery-related factors, suggesting a multi-factorial etiology.…”

“…19 Yet other studies have shown a detrimental effect of hyperthermia on cognitive outcomes. 15 The heterogeneity in the method, degree, and duration of hypothermia used are probably responsible, in large part, for the variability in the findings. A key feature of our study is the use of sustained hypothermia (without rewarming) compared with other trials, which may protect against the potentially harmful effects of cerebral hyperthermia.…”

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. 10,11 Given the mechanistic uncertainty behind POCD, it is not surprising that few interventions to date have been successful in ameliorating POCD in patients undergoing cardiac surgery.…”

Rapport sommaire: l’incidence décroissante de l’hyperthermie cérébrale pendant la cardiochirurgie, sept ans d’expérience auprès de 6 334 patients

“…1 Similarly, postoperative hyperthermia has also been reported to have adverse neurocognitive consequences. 4 These clinical deleterious effects of hyperthermia have been mirrored experimentally where the risk of damage after cerebral ischemia is increased by hyperthermia. 6 These factors suggest that either hyperthermia causes some de novo injury or further complicates injury once it has already occurred.…”