Correlation Between Baseline Perfusion Index and Post-Spinal Hypotension in Patients Undregoing Orthopaedic Surgery

Objective: To determine the correlation between baseline perfusion index and post-spinal hypotension. Study Design: Prospective longitudinal study Place and Duration of Study: Combined Military Hospital, Rawalpindi from April to July, 2021. Methodology: Male and female ASA I and II adult patients undergoing elective orthopaedic surgery under spinal anaesthesia were included in the study. Non-randomized, consecutive sampling was used. Brachial Non Invasive Blood Pressure (NIBP) was measured before administration of spinal anaesthesia and immediately post-spinal plus 2 additional readings at 3 minute intervals. Lowest post-spinal NIBP reading for a subject was considered in determining occurrence of hypotension. Hypotension was defined as either a drop of systolic B.P. to 100 mmHg or lower, or a drop to 80% baseline or lower. Results: Of the 371 subjects, 189(50.9%) were male. Mean age was 47.19±18.93 years. 203(54.7%) subjects were ASA I. Most frequently performed procedure was Knee Arthroscopy (n=54 [14.6%]). Mean Perfusion Index at baseline was 3.52±2.05 (from 0.3 to 7.7). At baseline, mean systolic B.P. was 135.53±17.12 mmHg, mean diastolic B.P. was 76.10 ±12.27 mmHg, and mean MAP was 95.92±10.09 mmHg. Post-spinal mean values were 112.37±17.24 mmHg for systolic, 68.19±11.65 mmHg for diastolic, and 82.60±10.85 mmHg for MAP, respectively. Overall, 201(54.2%) of the subjects exhibited post-spinal hypotension. Correlation between PI and Post-spinal Hypotension revealed a statistically significant association (p =0.043). Conclusion: A higher PI score at baseline could have predictive value for development of post-spinal hypotension in orthopaedic procedures. Further studies are needed to determine utility of PI as a predictor of ..