Effect of Autonomic Nervous System Dysfunction in Breast Cancer Patients on Post-induction and Early Intraoperative Hypotension: A Prospective Observational Study

BACKGROUND: Autonomic nervous system (ANS) dysfunction is increasingly recognized as a significant complication in cancer patients, potentially affecting perioperative hemodynamic stability. We evaluated the prevalence of ANS dysfunction in breast cancer patients and its association with post-induction hypotension during surgery. METHODS: This prospective, observational, double-blinded study was conducted from September 2018 to August 2019 at the All India Institute of Medical Sciences (AIIMS), New Delhi. Sixty-nine adult female patients with breast cancer scheduled for surgery under general anesthesia were enrolled. Preoperative autonomic function was assessed using standardized cardiovascular tests, including heart rate response to deep breathing, Valsalva maneuver, handgrip test, cold pressor test, and postural challenge test. ANS dysfunction was defined as abnormal results in two or more tests. Post-induction hypotension was defined as >30% decrease from baseline systolic blood pressure or absolute SBP <90 mm Hg. RESULTS: Among 62 patients with complete autonomic test results, ANS dysfunction was highly prevalent (49/62, 79.0%). Sympathetic dysfunction was present in 38 of 62 (61.3%), parasympathetic dysfunction in 25 of 62 (40.3%), and combined dysfunction in 14 of 62 (22.6%) of patients. The overall incidence of post-induction hypotension was 22 of 69 (32%). However, no significant association was found between ANS dysfunction and post-induction hypotension (sympathetic: odds ratio [OR], 1.04; 95% confidence interval [CI], 0.35-3.07; P = 1.00 and parasympathetic: OR, 1.17; 95% CI, 0.40-3.41; P = .79 and combined: OR, 1.11; 95% CI, 0.32-3.87; P = 1.00). Age was significantly associated with parasympathetic dysfunction (mean ± standard deviation [SD], 52.3 ± 9.7 vs 42.8 ± 9.9 years; P < .001), whereas comorbidities were not significantly associated (8/25 [32.0%] vs 4/37 [10.8%]; P = .052). CONCLUSIONS: Despite a high prevalence of ANS dysfunction in breast cancer patients, it was not associated with post-induction hypotension. The occurrence of hypotension appears independent of autonomic status in this population, suggesting that other mechanisms may contribute to perioperative hemodynamic instability.