INTRAOPERATIVE HYPOTENSION AND THE INCIDENCE OF POSTOPERATIVE ACUTE KIDNEY INJURY FOLLOWING ELECTIVE SURGERY IN ELDERLY PATIENTS

ARIYARATHNA D1, NAN K1, WONG G1, NIM J1, HUANG C1, BHONSLE A1, SIM N1, HONG J1, LIM A2

1Department of General Medicine, Monash Health, Clayton, Australia, 2Department of General Medicine, Monash Health, Department of Nephrology, Monash Health, Monash University Department of Medicine School of Clinical Sciences , Clayton, Australia

Background: Elderly patients are susceptible to intraoperative hypotension. A systolic blood pressure (SBP) <80 mmHg occurs in 40% of patients undergoing anaesthesia. Intraoperative hypotension may be a major contributor to postoperative AKI in elderly patients.

Aims: To determine the incidence of postoperative AKI in elderly patients after elective surgery and the association with intraoperative hypotension.

Methods: We conducted a retrospective cohort study of elective noncardiac surgery patients aged ≥65 years at Monash Health from 2017-2020. Patients with preoperative AKI, length of stay <48 hours or did not require a general anaesthetic were excluded. Intraoperative hypotension was defined as a mean arterial pressure (MAP) <60 mmHg or a SBP <90 mmHg. Postoperative AKI was defined using the KDIGO creatinine criteria.

Results: We included 653 patients (mean age 74 years, 52% male, 28% diabetics, median length of stay 5 days) with a median baseline creatinine of 77 (IQR, 64-93) µmol/L. The median duration of surgery was 151 min (IQR, 100-238 min). The incidence of intraoperative hypotension was 49%, with 21% experiencing 2 or more episodes. Most episodes of hypotension were mild and brief, with 95% of low SBP and 85% of low MAP lasting ≤10 minutes. The incidence of AKI was 1.2% (all Stage 1). Perioperative nephrotoxin exposure and contrast scans occurred in 21.6% and 7.4% of patients, respectively. Blood loss needing transfusions occurred in 4.4%. AKI was associated with higher baseline serum creatinine (OR 1.05 per 10 µmol, 95% CI: 1.01-1.10, p=0.02) but not with intraoperative hypotension.

Conclusion: Most episodes of intraoperative hypotension were brief and were not associated with postoperative AKI in elderly patients after elective noncardiac surgery. A larger cohort is needed for confirmation.


Biography:

MBBS UNSW 2011

Nephrology Advance Trainee- Liverpool Network

UNSW Conjoint lecturer

Geriatric Advance Trainee- Monash Health Network

RACP Continuing Professional Development Completion

Monash University Associate

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