Effect of smoking on perfusion index in assessment of the brachial plexus blockage success

Peripheral nerve block methods are increasingly used in extremity surgery. In order to evaluate the success of the block, non-invasive, easy and objective methods that provide rapid evaluation and do not require patient cooperation are required. It is known that there are changes in the peripheral vessels in terms of vasoconstruction in smokers. Perfusion index (PI) is an objective method used in the assessment of nerve block success and is affected by flow changes in the peripheral vasculature. The aim of the study is to evaluate the effect of smoking on PI values used in the assessment of success of the blockage in patients who underwent peripheral nerve blockage in upper extremity surgery. Ninety patients between the ages 18-60, with ASA physical status I-III, who will undergo upper extremity peripheral nerve block in Gaziantep University Faculty of Medicine, Anesthesiology and Reanimation Clinic, were enrolled to the study. The patients were divided into 2 groups each with 45 smokers and non-smokers. Nerve block was applied to all patients with in-plane technique by visualizing the nerve with the linear probe of ultrasound. After negative aspiration, 20 ml 0.25% bupivacaine + 1% lidocaine combination was injected. After the block process was completed, HR, MAP, SpO2 values at 0, 10, 20, 30. minutes were recorded. PI, capillary filling time, and distal skin temperature were measured and recorded simultaneously in both the limb where the block was performed and the contralateral limb at the same time. In the same time periods; Sensory examination with heat loss test, motor strength assessment with Modified Bromage scale and sensory block with pinprick test were evaluated and recorded. The compliance of the data to normal distribution was tested with the Shaphiro Wilk test, the Mann Whitney U test was used to compare the non-normally distributed features in 2 independent groups, and the Wilcoxon test was used for the comparison of 2 dependent groups. In this study, it was observed that the PI value in smoking patients was significantly higher than in non-smokers. PI values at the 10th, 20th and 30th minutes were also found to be significantly higher in smokers. (p <0.05). It was observed that the body temperature at the 20th minute was significantly higher in non-smoking patients (p = 0.014). There was no significant difference between the two groups in terms of cold sense block time, motor block onset time, pinprick test time, and capillary filling time.PI is a practical and effective method for evaluating the success of block in PSB applications in the upper extremity. According to our results PI values after nerve blockage were increased in smokers. If PI will be used to evaluate the success of PNB in patients with chronic smoking, prospective studies with higher sample sizes are needed to establish a corrected PI value.