INTRODUCTION
Different hypothermia regimens alone or combined with selective cerebral perfusion can be used for cerebral protection during surgical interventions involving the aortic arch. Historically, cooling of the brain to profoundly hypothermic levels seemed safe. However, transitions to warmer hypothermic temperatures in conjunction with antegrade cerebral perfusion has become the trend in the last decades1-3. Despite favorable clinical results reported with newer techniques, a variation in hypothermia regimes persists to exist between centers worldwide.
Evidence on outcome differences between the proposed techniques and different levels of hypothermia during aortic arch surgery is scattered across many publications. Over the last decades, several meta-analyses have compared different levels of hypothermia in different combinations in a pairwise fashion 4-7. However, no meta-analysis has compared all 3 levels of hypothermia, deep, moderate and mild.
Network meta-analysis (NMA) allows comparisons between more than 2 treatment arms. The advantage of network meta-analysis is that it facilitates indirect comparisons of multiple interventions that have not been studied in a head-to-head fashion 8. Hence we have used a network meta-analysis approach to compare the effect of deep hypothermic circulatory arrest (DHCA), moderate hypothermic circulatory arrest (MHCA) and mild hypothermic circulatory arrest (mild HCA) on the operative mortality, postoperative occurrence of stroke and acute kidney renal failure (AKI) after aortic arch surgery.