Comparison of Two Different Technique of Interscalene Block in Orthopedic Patients Undergoing Shoulder Surgery

ABSTRACT

The traditional Interscalene brachial plexus block has a 100% incidence of diaphragmatic paralysis, resulting in a 25-30% reduction in forced vital capacity (FVC). A modified or low Interscalene block is defined as a brachial plexus nerve block below C6 but above the supraclavicular fossa. The purpose of our study was to determine if a modified Interscalene block would prevent diaphragmatic paralysis while providing an adequate pain control for patients undergoing shoulder surgery. Methods: 50 patients who were scheduled to undergo shoulder surgery were incorporated in the study. Patients were randomized to receive either a low (LI) or a traditional (TI) interscalene nerve block. Both groups received 15ml of 0.5% Bupivacaine diluted to 30ml for brachial plexus block. Post-block lung function was assessed using incentive spirometry. Results: The average decrease in lung volume in the group receiving the low-modified interscalene block was 900ml, while the decrease in the traditional group was 860ml. The decrease in lung volumes between the two groups was determined to be not significant (p= 0.525). Conclusion: Low interscalene brachial plexus blockade is often described as a technique used to prevent phrenic nerve blockade and hemi-diaphragmatic paralysis. Our study found that phrenic nerve blockade was low in LI group as compared to TI group. Postoperative pain scores, respiratory complications, need for supplemental oxygen, and delay in discharge did not occur in either group. We found that LI interscalene brachial plexus blockade not better than TI interscalene block.