Consensus on hypothermia in aortic arch surgery

Abstract

Considered a standard part of aortic arch surgery, hypothermia can sufficiently reduce cerebral metabolic demand to permit reasonable periods of circulatory arrest. Yet despite its ubiquitous application and critical importance, temperature classification in hypothermic circulatory arrest is still without clear definition. The following Consensus from experts in high-volume aortic institutions defines 'profound', 'deep', 'moderate', and 'mild' hypothermia and recommends standardized monitoring sites, so as to facilitate more consistent reporting and robust analysis.

Keywords: Aortic arch surgery; cerebral protection; consensus statement; hypothermic circulatory arrest.

Figure 1

The proportion of patients for whom electrocerebral silence is achieved at a given nasopharyngeal temperature. Proposed categories are superimposed in dark red. (Modified from Stecker et al.)

Figure 2

Cumulative probability representation that electrocerebral silence (ECS) is not achieved for temperatures above that indicated. For example, at 20 °C, 75% of patients have not achieved ECS. Proposed categories are superimposed in dark red. (Modified from Stecker et al.)

Figure 3

Cerebral metabolic rate, as percentage of baseline, at various esophageal temperatures, and estimated safe duration of HCA. Proposed categories are superimposed in dark red. (Modified from McCullough et al.)

Figure 4

Temperature variations at various sites as compared to the brain during cerebral aneurysm repair. Each coloured bar represents change compared to brain temperature at various stages of cooling. The esophageal temperature most closely resembles cortical temperature, followed by the pulmonary artery and nasopharyngeal temperature. The rectum and bladder are considerably warmer than the brain during cooling and cooler during rewarming, while the opposite is true for the perfusate temperature (Modified from Stone et al.)