Data Extraction
Microsoft Office Excel 2016 (Microsoft Corp., Redmond, WA, USA) was used
for data extraction. Two reviewers (D.A. and G.T.) independently
extracted the data and recorded all data with a standardized form. All
two-arm (two groups reported) studies with a within-study comparison of
different hypothermia regimens, regardless of cerebral perfusion
strategy, were extracted. The different levels of hypothermia were
classified as following: deep hypothermia (≤20°C), moderate hypothermia
(20.1°C to 25°C), mild hypothermia (≥ 25.1°C). The cutoff of 20°C to
separate the patients into moderate vs. deep hypothermia cohorts was
consistent with the International Aortic Arch Surgery Study Group
(IAASSG) consensus guideline regarding the nomenclature of hypothermia
during aortic arch surgery 10. In the literature,
moderate hypothermia is often referred to as low-MHCA, while mild
hypothermia is often considered high-MHCA. Concerning the location of
temperature measurement, the rectal temperature was reported in almost
all studies. If no rectal temperature was present in a publication, the
nasopharyngeal temperature was reported. Outcomes were considered early
outcomes when they occurred within 30 days postoperatively or during the
period of initial hospital admission. Extracted baseline characteristics
and outcome measures are provided in Supplementary Material, Table S1.