Perfusion Index as a Predictor of post-Spinal Anaesthesia Hypotension in Geriatric Patients: A Prospective Observational Study

Post-spinal anaesthesia hypotension increases the risk of morbidity and mortality in elderly compared to the non-elderly population, making it a critical concern in perioperative care for geriatric population. Various modalities have been studied to predict the occurrence of hypotension following spinal anaesthesia, but they are invasive, expensive and need a significant level of expertise. The perfusion index is a simple, non-invasive and cost-effective monitoring tool to monitor peripheral vascular tone and various studies documented its potential as an early predictor of hypotension. Given the increasing number of elderly patients undergoing surgery with spinal anaesthesia, the accurate prediction of post-spinal anaesthesia hypotension is crucial for timely intervention and better patient outcomes, and the perfusion index shows potential as an early indicator of hypotension. However, its predictive accuracy in the geriatric population is not well established. This study aims to evaluate the efficacy of baseline PI as a predictor of post-spinal anaesthesia hypotension in geriatric patients.

After taking informed consent 92 patients of age more than 60 years with ASA II-III patients of either sex  undergoing elective surgery under spinal anaesthesia will be enrolled. Patient  with ASA status IV,  peripheral vascular disease, Significant cardiac disease ( more than grade II LV diastolic dysfunction, arrhythmia, pacemaker, LV or RV heart failure, ejection fraction  less than 50%, moderate to severe valvular heart disease), renal, pulmonary, hepatic and neurological disease, uncontrolled hypertension, history of brain injury or cerebrovascular disease, on psychiatric medication, especially lithium and patients undergoing Complex surgical procedures with anticipated substantial fluid shifts and intraoperative hemodynamic instability and patints having contraindications to spinal anaesthesia (bleeding tendency, allergy to local anaesthetics, sepsis, infection of the needle insertion site) will be excluded. Each patints will receive spinal anaesthesia as per study protocol and PI and other haemodynamic parameters (HR, SBP, DBP. MAP) will be recorded at baseline (after a 5-minute stabilization period following monitor attachment), just after administration of spinal anaesthesia, then 2.5-minute intervals for the first 30 minutes and every 5-minute intervals for a further 60 minutes and then at 15 minutes interval till the end of surgery.

SPSS software or an equivalent program will be used for analysis. The correlation between various parameters will be assessed using the Pearson correlation coefficient for linear relationships and the Spearman correlation coefficient for non-linear relationships. Regression analysis with Spearman’s rank correlation coefficient will be used to assess the correlation between baseline PI with post-spinal hypotension. Multiple linear regression analysis will be performed to explore the relationships between patients’ characteristics and baseline parameters with post-spinal hypotension. A receiver operating characteristic (ROC) curve will be generated for baseline PI compared with hypotension. The area under the curve (AUC) will be calculated to measure the accuracy of the parameter, and the optimal cut-off point, which minimizes false-positive and false-negative rates, will be identified. A significance level of P < 0.05 will be considered statistically significant. A significance level of P < 0.05 will be considered indicative of statistically significant differences.