Intraoperative Hypotension: Immediate and Short Term Impact on Mortality. Findings from a High Dependency Cardiac and Vascular Surgical Center in Nigeria

Abstract: Introduction: Intraoperative hypotension in cardiac surgery could be complicated by acute kidney injury (AKI), cardiac arrest and death due to poor organ perfusion. We studied intraoperative hypotension (IOH) and its immediate and short term relationship with post-operative mortality. Materials & Methods: A retrospective study of participants, 16-86 years old who underwent cardiac and vascular surgery at Tristate Heart and Vascular Center, Ilishan-Remo, Nigeria, a high dependency cardiac and vascular surgical center between January 2015 and March 2021. Study participants were grouped into three cohorts and primary outcome was all-cause post-operative death. Results: The records of four hundred and fifteen (258 males and 157 females) cohorts were studied, with mean age of 56.6 ± 5.4 years, 14.69% of the participants were 65 years or older. The surgeries were coronary artery bypass graft (CABG) alone (26.03%), CABG with valve surgery (38.31%) and, valves surgery alone (35.66%). The mean arterial pressure (MAP) pre-induction, and intra-operative and immediate post-op were 71.37 ± 14 09 mmHg, 68.6 ± 11.24 mmHg and 72.24 ± 33 mmHg respectively. The incidence of IOH was 86.30%, prevalence of background kidney dysfunction was 29.40% and incidence of AKI was 25.54%. Eleven (2.65%) participants died, all (100%) had IOH, 1 (9.09%) was intradialytic. The predictors of mortality were aging (aOR-4.23, 1.65-5.85), IOH (aOR-1.55, CI-0.34-1.96), background kidney disease (aOR-3.96, CI-1.43-4.78), comorbidity (aOR-2.77, CI-0.87-3.17), emergency surgery (aOR-4.62, CI-1.35-5.12), pre-induction MAP (aOR-4.22, CI-3.15-6.49) and, combined CABG and valve surgery (aOR-2.17, CI-1.69-4.57)). Conclusion: Intraoperative hypotension commonly results from cardiac and vascular surgeries and could be complicated by AKI, cardiac arrest and death. The risk of these complications is increased by background kidney disease, comorbidities and episodes of IOH. Keywords: Intraoperative hypotension, Coronary artery bypass graft, Acute kidney injury, Cardiac arrest, Mortality, Mean arterial pressure.