Impact of Intraoperative Hemodynamic Instability on Outcomes in Cardiac Surgery

Impact of Intraoperative Hemodynamic Instability on Postoperative Major Adverse Events in Cardiac Surgery Patients: A Prospective Cohort Study

Intraoperative hemodynamic instability (IOHI) is a common occurrence during cardiac surgery and is associated with organ hypoperfusion. However, the specific impact of IOHI on composite adverse outcomes remains unclear. This prospective cohort study aims to evaluate the association between intraoperative hemodynamic instability (defined as MAP < 65 mmHg or vasopressor requirement) and major postoperative complications (Delirium, Acute Kidney Injury, Stroke, or Mortality) in adult patients undergoing elective cardiac surgery with cardiopulmonary bypass.

Hemodynamic instability during cardiac surgery is a critical factor influencing postoperative recovery. While transient hypotension is common, prolonged instability may lead to end-organ damage due to hypoperfusion. This prospective observational study will be conducted at the University of Health Sciences Gazi Yasargil Training and Research Hospital.

Patients scheduled for elective cardiac surgery (Coronary Artery Bypass Grafting, Valve replacement/repair, or combined procedures) utilizing cardiopulmonary bypass will be enrolled. Intraoperative hemodynamic data, including Mean Arterial Pressure (MAP), heart rate, and vasoactive medication requirements, will be recorded.

Patients will be categorized into two groups based on intraoperative stability:

1. Hemodynamic Instability Group: Patients experiencing MAP < 65 mmHg for more than 5 minutes continuously or requiring significant vasopressor/inotropic support to maintain target pressure.
2. Stable Group: Patients maintaining hemodynamic stability without significant hypotensive episodes.

The primary endpoint is a composite of major adverse events within 30 days, including Postoperative Delirium (assessed via CAM-ICU), Acute Kidney Injury (KDIGO criteria), Stroke, and All-cause Mortality. Secondary endpoints include the duration of mechanical ventilation and length of ICU/hospital stay. The study aims to provide evidence-based thresholds for intraoperative blood pressure management to improve patient outcomes.

Inclusion Criteria:

• Patients aged 18 years or older.
• Scheduled for elective cardiac surgery (CABG, Valve replacement/repair, or combined procedures).
• Surgery performed under cardiopulmonary bypass (CPB).
• Preoperative sinus rhythm.
• Signed informed consent form.

Exclusion Criteria:

• Emergency or salvage surgery.
• Off-pump coronary artery bypass grafting.
• Preoperative mechanical circulatory support (IABP, ECMO) requirement.
• Pre-existing chronic renal failure requiring dialysis (HD/PD).
• Pre-existing cognitive impairment, dementia, or history of psychiatric disorders affecting cooperation.
• Pregnancy.