Dear Editor,

Acute kidney injury (AKI) frequently occurs as a complication in patients undergoing cardiac surgery, with reported incidence rates ranging from 20 to 40% [1]. The development of cardiac surgery-associated AKI (CSA-AKI) is linked to adverse outcomes such as increased short- and long-term mortality, as well as prolonged hospital stays [1].

Despite its significance, the underlying mechanisms of CSA-AKI remain inadequately understood and research concerning optimization of perioperative management to mitigate CSA-AKI is needed [2].

While a link between mean arterial pressure (MAP) under 65 mmHg and AKI has been established in noncardiac surgery patients [3], there is still controversy regarding this association in cardiac surgery patients, particularly during cardiopulmonary bypass (CPB), a critical period with nonpulsatile albeit constant flow, altered hemodynamics, decreased oxygen delivery and oxidative stress, each of which potentially contribute to CSA-AKI [2].

We hypothesized that an increase in time-weighted average (TWA) MAP under 65 mmHg during CPB is associated with the development of CSA-AKI.

To generate reproducible and transparent results, we analyzed the publicly available INSPIRE-research-dataset, which provides high-resolution multi-parameter data of patients who underwent anesthesia for surgery at an academic institution in South Korea between 2011 and 2020 [4].

All patients who underwent CPB during cardiac surgery with availability of invasive MAP data with at least five-minute resolution were included.