Article Text

Download PDFPDF
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
  1. Xiuxia Bao1,2,
  2. Juanjuan Huang1,
  3. Haorong Feng1,
  4. Yuying Qian1,
  5. Yajie Wang1,
  6. Qunying Zhang1,
  7. Huansheng Hu1 and
  8. Xianghe Wang1
  1. 1 Department of Anesthesiology, The 98th Clinical College of PLA, Anhui Medical University, Huzhou, China
  2. 2 Department of Anesthesiology, The First Affiliated Hospital Zhejiang University, Hangzhou, China
  1. Correspondence to Xianghe Wang, The 98th Clinical College of PLA, Anhui Medical University, Huzhou 313000, China; 863097{at}


Background and objectives Diaphragmatic 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.

Methods Eighty 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.

Results Block 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).

Conclusions The 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 number ChiCTR-IND-17012166.

  • supraclavicular block
  • ultrasound
  • electromyography
  • pulmonary function

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.


  • Competing interests None declared.

  • Patient consent Obtained

  • Ethics approval Institutional approval for this study was obtained from the Medical Ethics Committee at our institution (Medical ethics of the 98th Hospital of PLA of China).

  • Provenance and peer review Not commissioned; externally peer reviewed

Linked Articles