Effect of local anesthetic volume (20 mL vs 30 mL ropivacaine) on electromyography of the diaphragm and pulmonary function after ultrasound-guided supraclavicular brachial plexus block: a randomized controlled trial

Abstract

Background and objectivesDiaphragmatic paralysis following supraclavicular brachial plexus block (SCBPB) is ascribed to phrenic nerve palsy. This study investigated the effect of 2 volumes of 0.375% ropivacaine on efficacy of block as a surgical anesthetic and as an analgesic and examined diaphragm compound muscle action potentials (CMAPs) and pulmonary function before and after SCBPB.MethodsEighty patients scheduled for removal of hardware for internal fixation after healing of an upper limb fracture distal to the shoulder were randomized to receive ultrasound-guided SCBPC for surgical anesthesia with 20 mL (Group A) or 30 mL (Group B) 0.375% ropivacaine. The latency and amplitude of diaphragm CMAPs and forced vital capacity (FVC), FVC% predicted, and forced expiratory volume in 1 s (FEV1) were measured before and 30 min after SCBPB.ResultsBlock success as primary anesthetic in addition to analgesia was 81% in Group A and 91% in Group B. There were no obvious differences in the effectiveness of analgesia between the two groups. The mean time to onset of motor block was significantly longer in Group A (8.1±2.7 min) than in Group B (5.4 ± 2.8 min; p<0.05). The mean amplitude of the diaphragm CMAP was significantly lower in Group B than in Group A (p=0.03). The changes in FVC (Group A, − 8.1% vs Group B, −16.5%), FVC% (Group A, −8.0% vs Group B, −17.1%), and FEV1 (Group A, −9.5% vs Group B, −15.2%) from pre-SCBPB to post-SCBPB were significantly less in Group A than in Group B (all p=0.03).ConclusionsThe incidence rates of phrenic nerve palsy and diaphragm paralysis were reduced, and lung function was less impaired in patients who received 20 mL vs 30 mL of 0.375% ropivacaine without any differences in block success. Selecting a lower volume of anesthetic for nerve block may be especially beneficial in obese patients or patients with cardiopulmonary disease.Trial registration numberChiCTR-IND-17012166.

A Case Report of Bilateral Phrenic Nerve Dysfunction After Unilateral Supraclavicular Brachial Plexus Block: Unveiling Preexisting Diaphragmatic Dysfunction

“…Specifically, 20 mL or less of local anesthetic volume has been demonstrated to have a lower incidence of diaphragmatic dysfunction than 30 mL for supraclavicular block. 3,4 The patient's presentation and point-of-care ultrasound were consistent with bilateral phrenic nerve dysfunction, from blockade of the phrenic nerve related to supraclavicular block on the right and postoperative phrenic nerve injury on the left. While she ultimately tolerated surgery with minimal sedation, supplemental oxygen, and the head of the bed elevated to optimize respiratory mechanics, our team was prepared for possible intubation and mechanical ventilation, given her risk of complete respiratory collapse.…”

The Amplitude of Diaphragm Compound Muscle Action Potential Correlates With Diaphragmatic Excursion on Ultrasound and Pulmonary Function After Supraclavicular Brachial Plexus Block

“…These data highlight the unmet clinical need to raise awareness about diaphragmatic paralysis as a complication of brachial plexus block and identify novel methods to measure diaphragmatic paralysis. Previously, we explored the effect of 20 and 30 ml of 0.375% ropivacaine on electromyography of the diaphragm and pulmonary function before and after ultrasound-guided SCBPB ( 21 ).…”

Sequential supraclavicular brachial plexus and stellate ganglion neurolysis for upper limb pain in metastatic breast cancer

“…As there was a risk of phrenic nerve blockade and inadvertent spread, the total volume injected was kept to a minimum in both blocks to avoid complications. [ 11 12 ] It is worthwhile to mention that radiofrequency ablation could have been performed for the brachial plexus block. We chose to proceed with the chemical neurolysis as the plexus was compressed and not visualized properly, and hence, it would have been difficult to locate all the trunks and incomplete lesion was a possibility.…”