A Study on Predicting Succesfull Sub Arachnoid Block Using Pulse Oximetry Perfusion Index.

Abstract

Aim: To analyse the role of perfusion index variations after performing regional anaesthesia in predicting a successful spinal anaesthesia.

Materials and methods: The study was conducted with a sample size of 100 patients, at Saveetha College of Allied Health Sciences (SCAHS) from August 2021 to February 2022. Following approval from the Institutional Review Board (IRB) and Ethical Committee Clearance, eligible patients were enrolled after obtaining written informed consent. Perfusion index (PI) measurements were recorded before regional anesthesia and at 1, 2, 3, 5, and 10 minutes after needle withdrawal to assess the role of PI variations in predicting a successful nerve block. A multiparameter patient monitor equipped with PI functionality will be utilized for data collection. Additionally, sensory responses to cold (ice test), tactile sensation, and motor function will be documented before regional anesthesia and at the specified time points post-needle withdrawal on the limb undergoing the block.

Results: At 1-minute post-needle withdrawal, the mean PI value was 1.847. As time progressed, there was a noticeable increase in PI values, with the mean PI reaching 3.681 at 3 minutes, 6.03 at 5 minutes, and 9.595 at 10 minutes post-needle withdrawal. At 1-minute post-needle withdrawal, the average level of sensory loss was 9.6. This level decreased to 6.1 at 3 minutes, then further decreased to 4.12 at 5 minutes, and remained relatively stable at around 4.0 from 10 to 15 minutes post-needle withdrawal.

Conclusion: PI has demonstrated utility in assessing the efficacy of spinal block procedures when compared to the pin prick test. However, the determination of cutoff values should be tailored individually and considered alongside the ascending trend in PI. Application of these study findings in the operating room setting may be beneficial for patients with limited compliance with the pin prick test. Spinal anesthesia induces differential blood flow distribution between blocked and unblocked areas. Toe PI increases in response to vasodilation after spinal anesthesia,