The Impact of Intra-Abdominal Pressure on Mortality and Morbidity in Patients Undergoing Open-Heart Surgery

This prospective observational cohort study investigated perioperative changes in intra-abdominal pressure in patients undergoing elective open-heart surgery with cardiopulmonary bypass and examined whether increased intra-abdominal pressure was associated with postoperative recovery and adverse clinical outcomes.

Intra-abdominal pressure was assessed indirectly through urinary bladder pressure using a standardized measurement technique. Patients were placed in the supine position, 25 mL of sterile saline was instilled into the bladder, and pressure was recorded at end-expiration after zeroing the pressure transducer at the mid-axillary line. Measurements were obtained after induction of anesthesia, after sternal closure, and two hours after admission to the intensive care unit.

Intra-abdominal hypertension was defined as an intra-abdominal pressure of 12 mmHg or higher at any measurement time point. Patients meeting this definition were compared with patients whose intra-abdominal pressure remained below 12 mmHg at all measurements. Demographic, clinical, hemodynamic, laboratory, surgical, and postoperative data were collected prospectively.

No study-specific treatment or intervention was assigned. Anesthetic management, cardiopulmonary bypass management, fluid therapy, hemodynamic support, and postoperative care were provided according to routine institutional practice. The analyses were designed to evaluate associations between intra-abdominal hypertension and postoperative outcomes and to explore perioperative factors associated with increased intra-abdominal pressure. Because the study was observational, the findings were interpreted as associations rather than evidence of causality

Inclusion criteria

• Age 18 years or older
• Scheduled for elective open-heart surgery using cardiopulmonary bypass
• Left ventricular ejection fraction of 40% or higher
• Provision of written informed consent

Exclusion criteria

• Age under 18 years
• Requirement for emergency cardiac surgery
• Open-heart surgery performed without cardiopulmonary bypass
• Body mass index of 35 kg/m² or higher
• Uncontrolled diabetes mellitus
• History of urinary bladder or urinary tract surgery
• Active urinary tract infection
• Acute or chronic renal failure
• Neurogenic bladder
• History or presence of cerebrovascular disease