Preoperative Subclavian/Infraclavicular Axillary Vein Collapsibility Index for Predicting Hypotension After Spinal Anaesthesia in Geriatric Patients Undergoing Lower-Limb Surgery: A Prospective Observational Study

Background: Hypotension after spinal anaesthesia is common in older adults and may compromise organ perfusion. This study evaluated whether preoperative subclavian/infraclavicular axillary vein collapsibility index (SCV/AV-CI) predicts post-spinal hypotension in geriatric patients undergoing lower-limb surgery. Material and Methods: In this prospective observational study, 100 patients aged >60 years with American Society of Anesthesiologists physical status I-III were evaluated. Right SCV/AV maximum and minimum diameters were measured during normal and deep breathing, and collapsibility indices were calculated. Hypotension was defined as a >20% reduction in mean arterial pressure from baseline. Diagnostic performance was assessed using receiver-operating characteristic analysis. Multivariable logistic models adjusted for age, ASA III status, baseline mean arterial pressure, and fasting duration. Results: Hypotension occurred in 69 patients (69%). Normal-breathing CI was higher in patients with hypotension than in those without hypotension (32.63 ± 7.59% vs 17.42 ± 7.97%; P<0.001), as was deep-breathing CI (39.07 ± 7.76% vs 23.43 ± 8.43%; P<0.001). Normal-breathing CI yielded an area under the curve of 0.910 (95% confidence interval [CI], 0.839-0.964); a cutoff of ≥21.3% provided 92.8% sensitivity and 74.2% specificity. Deep-breathing CI yielded an area under the curve of 0.911 (95% CI, 0.839-0.966); a cutoff of ≥26.3% provided 97.1% sensitivity and 74.2% specificity. Each 5% increase independently increased the odds of hypotension (adjusted odds ratio, 3.60 and 3.48, respectively; both P<0.001). Conclusion: Preoperative SCV/AV-CI showed strong discrimination for post-spinal hypotension. Deep-breathing CI had high sensitivity and negative predictive value, but external validation is required before routine clinical use.

Keywords: Geriatrics; anaesthesia, spinal; hypotension; subclavian vein; ultrasonography; vascular collapsibility.