Introduction: The effect of hypothermic circulatory arrest temperature on postoperative acute kidney injury (AKI) has not been evaluated. This study examined the association between hypothermic circulatory arrest temperatures on AKI for patients undergoing proximal aortic or aortic arch repair.
Methods: N=759 patients who underwent proximal aortic surgery including arch replacement requiring hypothermic circulatory arrest between July 2005-Decmember 2016 were identified from a prospectively maintained institutional aortic surgery database. The primary outcome was AKI as defined by RIFLE criteria. The association between minimum nasopharyngeal (NP) and bladder temperatures during hypothermic circulatory arrest and postoperative acute kidney injury was assessed, adjusting for patient level factors using multivariable logistic regression.
Results: Of the overall cohort, 85% underwent deep hypothermia (14.1-20.0C), 11% low-moderate hypothermia (20.1-24.0C), and 4% high-moderate hypothermia (24.1-28.0C ) as classified by NP temperature. When analyzed by bladder temperature, 59% underwent deep hypothermia, 22% low-moderate, 16% high-moderate, and 3% mild (28.1-34.0C) hypothermia. The incidence of AKI did not differ between hypothermia groups, whether analyzed using minimum NP or bladder temperature. In multivariable analysis, the association between degree of hypothermia and AKI remained non-significant whether analyzed as a categorical variable (hypothermia group) or as a continuous variable (minimum NP or bladder temperature) (all p>0.05).
Conclusions: In patients undergoing proximal aortic surgery including arch replacement requiring hypothermic circulatory arrest, degree of hypothermia was not associated with risk of AKI. These data suggest that moderate hypothermia does not confer increased risk of AKI for patients requiring circulatory arrest, although additional prospective data is needed.