# Identification of Risk Factors for Postoperative Hypotension Following Transurethral Bladder Tumor Resection Performed With Oral 5-Aminolevulinic Acid: A Multivariate Analysis of a Single-Center Retrospective Cohort Study

## TL;DR

This study identifies risk factors for postoperative low blood pressure after bladder tumor surgery using 5-ALA, focusing on kidney function and pre-surgery blood pressure.

## Contribution

The study is the first to identify risk factors specifically for postoperative hypotension following TUR-Bt with 5-ALA.

## Key findings

- Impaired renal function (eGFR ≤ 45-60 or < 45 mL/min/1.73 m2) increases risk of postoperative hypotension.
- Lower preoperative mean blood pressure (< 95 mmHg) is associated with higher risk of postoperative hypotension.
- Risk factors were consistent across both general and spinal anesthesia groups.

## Abstract

Background

Transurethral resection of bladder tumors (TUR-Bt) using 5-aminolevulinic acid (5-ALA) is increasingly performed to visualize tumors. However, oral administration of 5-ALA frequently induces perioperative hypotension. Although several risk factors for intraoperative hypotension have been reported, those associated with postoperative hypotension have not yet been identified. We retrospectively evaluated risk factors for postoperative hypotension following TUR-Bt with 5-ALA administration.

Methods

The enrolled participants were patients who underwent TUR-Bt with 5-ALA under general or spinal anesthesia between July 2020 and December 2023. Patients who developed postoperative hypotension or used postoperative vasopressors were assigned to the hypotension group, and those who did not were assigned to the non-hypotension group. Postoperative mean blood pressure (mBP) was sampled from the electronic medical record at 1, 2, 3 and 6 hours after surgery. Postoperative hypotension was defined as an mBP of < 70 mmHg, noted at least once in the electronic medical records. Risk factors were identified using multivariate analysis. In addition, a subset of spinal anesthesia cases was similarly analyzed.

Results

Among 111 patients who underwent TUR-Bt with 5-ALA under general or spinal anesthesia, 46 and 65 were categorized into the hypotension and non-hypotension groups, respectively. Risk factors identified were estimated glomerular filtration rate (eGFR) ≤ 45-60 mL/min/1.73 m2, eGFR < 45 mL/min/1.73 m2, and mBP < 95 mmHg upon entering the operating room (odds ratio (OR) 3.026, 95% confidence interval (CI) 1.140-8.003, P = 0.027; OR 4.851, 95% CI 1.550-15.177, P = 0.007; and OR 2.443, 95% CI 1.018-5.865, P = 0.046, respectively). From the 111 patients, 88 underwent spinal anesthesia (38 hypotensive, 50 non-hypotensive). Risk factors identified among these patients were body mass index, eGFR ≤ 45-60 mL/min/1.73 m2, eGFR < 45 mL/min/1.73 m2, and mBP < 95 mmHg upon entering the operating room (OR 1.290, 95% CI 1.079-1.542, P = 0.006; OR 3.757, 95% CI 1.153-12.249, P = 0.029; OR 7.295, 95% CI 01.804-29.501, P = 0.006; and OR 3.134, 95% CI 1.061-9.262, P = 0.039, respectively).

Conclusion

Regardless of anesthesia method, impaired renal function increased postoperative hypotension, whereas higher blood pressure before anesthesia was less likely to result in postoperative hypotension.