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Three societies issue recommendations on temperature management during adult cardiopulmonary bypass surgery
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New clinical practice guidelines released jointly by the Society of Thoracic Surgeons, the Society of Cardiovascular Anesthesiologists and the American Society of ExtraCorporeal Technology provide recommendations on temperature management during cardiopulmonary bypass surgery, such as the best site for temperature monitoring and how to avoid hyperthermia.
“Numerous strategies are currently invoked by perfusion teams to manage the requirements of cooling, temperature maintenance and rewarming patients during cardiac surgical procedures. To date, there have been very few evidence-based recommendations for the conduct of temperature management during perfusion,” Richard Engelman, MD, from the department of surgery at Baystate Medical Center and Tufts University School of Medicine, Springfield, Massachusetts, and colleagues wrote in the Annals of Thoracic Surgery.
Based on existing research, during cardiopulmonary bypass (CPB) surgery, oxygenator arterial outlet blood temperature should be used as a surrogate for cerebral temperature measurement, according to the new guidance.
The authors also concluded that “to monitor cerebral perfusate temperature during warming, it should be assumed that the oxygenator arterial outlet blood temperature underestimates cerebral perfusate temperature.”
It is reasonable for surgeons to perform core temperature management by pulmonary artery or nasopharyngeal temperature recording.
Based on current research on hyperthermia, there is strong evidence that arterial outlet blood temperature should be limited to 37°C to prevent cerebral hyperthermia, according to the document.
Previous research on peak cooling temperature gradient and cooling rate indicated that temperature gradients upon cooling of more than 10°C are linked with gas emboli formation, so gradients between the arterial outlet and venous inflow blood temperatures should not exceed 10°C, the authors wrote.
Likewise, previous research on peak warming temperature gradient and rewarming rate indicated that outgassing can occur when the patient receives warm blood and temperature gradients between the arterial outlet and venous inflow blood temperatures exceeded 10°C, so the authors strongly cautioned against that practice.
When the arterial blood outlet temperature is 30°C or higher, it is reasonable to maintain a temperature gradient 4°C or lower, and it is reasonable to have a rewarming rate 0.5°C/minute or lower, according to the guidance. However, when arterial blood outlet temperature is less than 30°C, “it is reasonable to maintain a maximal gradient of 10°C between the arterial outlet and venous inflow temperature,” they wrote.
The current evidence base did not yield enough evidence to make a recommendation about the optimal temperature for weaning from CPB, according to the authors.
“The importance of accurately recording and reporting temperature management during CPB cannot be overstated,” Engelman and colleagues wrote. “Unfortunately, many published articles fail to document temperature management strategies during and after CPB. Temperature management during CPB remains controversial, with gaps in our knowledge concerning a variety of aspects of temperature management.” – by Erik Swain
Disclosures: The authors report no relevant financial disclosures.
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