Data included in the current analysis were collected between March 25th and October 1st, 2019 (Emory) and December 16th, 2020, and April 15th, 2021 (Wake Forest and Cleveland Clinic Florida) and represent pilot data from an ongoing large registry currently enrolling at centers across the country. We prospectively enrolled elective and emergent adult cardiac surgery patients at three large academic medical centers in the USA, undergoing a variety of on and off-pump cardiac surgical procedures needing open sternotomy. The Accuryn Monitoring System intra-abdominal pressure and CUO Foley catheter was inserted after induction of anesthesia and stayed in place along with the bedside measurement system util the patient stayed in the intensive care unit (ICU) or did not need a urinary catheter (whichever came first). While CUO data displayed as continuous output per unit time was used as part of routine care, IAP was not and was recorded passively and extracted retrospectively from the system.
We collected additional data such as age, gender, race and ethnicity, body mass index (BMI), vasopressors, inotropes, transfusions and extubation times from the electronic medical record. Data were deidentified on-site. BMI was further used to classify overweight and obesity according to the Center of Disease Control (CDC) . Accuryn Monitoring System data (IAP, CUO) were related to EMR data using a deidentified patient identifier. We excluded patients if they had less than 24 h of data from the Accuryn Monitoring System or if data variables were missing (extubation times were exempt from this missing data exclusion). Time to extubation was calculated from surgery end to better align with Fig. 1. We performed a separate analysis to describe IAP in the patients in whom the Accuryn Monitoring System was in place for less than 24 h. Data collection from the Accuryn Monitoring System was seized when Foley catheters were pulled, or patients left the ICU.
Intra-abdominal pressure and urinary output intra-operatively and for the first 48 postoperative hours. The red line represents surgery end. IAP intra-abdominal pressure; UO urinary output; IQR interquartile range; mmHg millimeter Hydrargyrum (Mercury); ml/kg/h milliliter/kilogram/hour
Histogram of median intra-abdominal pressure from surgery end to 24 h postoperatively. The median IAP within the first 24 postoperative hours was 15.9 [13.6, 18.7] mmHg. IAP intra-abdominal pressure; mmHg millimeter Hydrargyrum (Mercury)
IAP was measured beginning with induction of anesthesia and continued intraoperatively and after that for a median of 56.0 [46.8, 77.5] hours postoperatively. Intraoperatively (1 h or more before the end of surgery), most patients, 77% (105/137) remained within a normal IAP (
We qualitatively looked at the UO in relation to IAP (Fig. 1). In this postoperative timeline, UO appears lower with increased IAP during the study period, with higher UO seen intraoperatively than during the postoperative time in the ICU. Low UO is a hallmark of acute kidney injury (AKI), and KDIGO defines AKI as UO less than 0.5 ml/kg/h for more than 6 h (stage I) . AKI is a frequent form of IAH- induced organ dysfunction [12, 40]. In patients with ACS, AKI is established with anuria and the necessity for renal replacement therapy unless early intervention prevents these sequelae . A recent meta-analysis established the link between AKI and IAH in various patient populations including cardiac surgery . 153554b96e