Dynamic pupillometry to predict hypotension after spinal anesthesia in patients with diabetes mellitus – A prospective observational study

Abstract Background and Aims: Hypotension is a common adverse effect of spinal anesthesia and poses increased risks for patients with diabetes mellitus. While various tests exist for diagnosing diabetic autonomic neuropathy, dynamic pupillometry is a simple and cost-effective option. This study aimed to assess whether dynamic pupillometry can predict post-spinal hypotension in diabetic patients. Material and Methods: In this observational study, 75 patients with diabetes mellitus who were scheduled for surgery under spinal anesthesia underwent a pupillary examination the day prior. Both static and dynamic parameters were recorded. On the day of surgery, 3 ml of 0.5% hyperbaric bupivacaine was administered for spinal anesthesia, and instances of intraoperative hypotension and the use of vasopressors were noted. Results: Post-spinal hypotension occurred in 77% of the 75 patients studied, with 27 experiencing mild hypotension (20–30% drop in MAP) and 31 having severe hypotension (>30% drop). The severe hypotension group had a significantly lower baseline pupil radius (3.86 ± 0.52 mm) compared to the no hypotension group (4.37 ± 0.57 mm, P = 0.006). The area under the receiver operating characteristic curve for baseline pupil radius was 0.720, with a threshold of less than 4.01 mm showing 70.7% sensitivity and 70.6% specificity for predicting post-spinal hypotension. Conclusions: Baseline pupil radius measured using pupillometry may serve as a simple noninvasive marker to identify diabetic patients at risk of post-spinal hypotension.