The Rewarming Rate and Increased Peak Temperature Alter Neurocognitive Outcome After Cardiac Surgery

Abstract

Slower rewarming during cardiopulmonary bypass (CPB) was associated with better cognitive performance at 6 wk. These results suggest that a slower rewarming rate with lower peak temperatures during CPB may be an important factor in the prevention of neurocognitive decline after hypothermic CPB.

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

“…1,4,5 Elevated peak temperature, in concert with an increased rate of rewarming, has been associated with increased neurocognitive dysfunction following CPB. 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.…”

“…1,5,7,8 This increased awareness has likely led to an evolution of temperature management. As a result, we hypothesize that both the maximum temperature, as well as the incidence of cerebral hyperthermia, during cardiac surgery has decreased over time at our institution.…”

“…EREBRAL hyperthermia commonly occurs during rewarming from hypothermic cardiopulmonary bypass (CPB) and has been associated with increased neurocognitive dysfunction after cardiac surgery. 1 Rewarming from hypothermic CPB is principally accomplished by delivering energy to the blood as it circulates through the heat exchanger of the CPB apparatus. Elevated arterial inflow temperatures (> 37°C) have been used extensively in the past to facilitate a more rapid rewarming from hypothermic CPB.…”

Limiting brain and lung damage after coronary artery bypass grafting: An alternative to conventional coronary artery bypass graft

“…19 Thus, despite intense interest in hypothermia, studies comparing various temperatures and rewarming approaches have not clarified this issue. 20,21 (4) Normal, physiologic pulsatile flow is replaced by nonpulsatile flow during cardiopulmonary bypass. Cerebral blood flow and microvascular blood flow both decrease, while the expression of inflammatory mediators in blood and vascular cells increases when pulsatile flow is replaced with nonpulsatile flow.…”

Hypothermia or normothermia after cardiac arrest? Do not throw the baby out with the bath water?

“…However, in the Nielsen trial, the control group was also a TTM group keeping the normothermia group meticulously at 36°C. These 1.3-1.6°C differences in temperature compared to the Bernard and the HACA studies should be interpreted as relevant, and may be an explanation for differences in effects among TTM studies [14,15]. Thus the ''normothermia group'' in the Nielsen TTM trial in fact is a TTM group, with body temperature targets purposely, rigorously and actively kept at 36°C.…”