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  • Clinical effect of normal saline injectate into interscalene nerve block catheters given within one hour of local anesthetic bolus on analgesia and hemidiaphragmatic paralysis

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Original research
Clinical effect of normal saline injectate into interscalene nerve block catheters given within one hour of local anesthetic bolus on analgesia and hemidiaphragmatic paralysis
  1. Lynn Ngai Gerber1,2,
  2. Lisa Y Sun3,
  3. Wen Ma2,
  4. Shruthi Basireddy1,
  5. Nan Guo1,
  6. John Costouros4,
  7. Emilie Cheung5,
  8. Jan Boublik1,
  9. Jean-Louis Horn1 and
  10. Ban CH Tsui1
  1. 1Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University, Stanford, California, USA
  2. 2Department of Anesthesiology, Santa Clara Valley Medical Center, San Jose, California, USA
  3. 3Department of Anesthesiology, University of Minnesota, Minneapolis, Minnesota, USA
  4. 4Orthopedic Surgery, Institute for Joint Restoration and Research, Menlo Park, California, USA
  5. 5Department of Orthopedic Surgery, Stanford University, Stanford, California, USA
  1. Correspondence to Dr. Ban CH Tsui, Anesthesiology, Perioperative and Pain Medicine, Stanford University, Palo Alto, CA 94305, USA; bantsui{at}stanford.edu

Abstract

Background Previous case reports describe the reversal of phrenic nerve blockade from the interscalene nerve block using normal saline injectate washout. This randomized clinical trial aimed to evaluate whether using normal saline injectate to wash out local anesthetic from an interscalene nerve block catheter would restore phrenic nerve and diaphragm function, while preserving analgesia.

Methods Institutional review board approval, clinical trial registration and consent were obtained for patients undergoing shoulder surgery with an interscalene nerve block catheter. 16 patients were randomized to receive three 10 mL aliquots of normal saline injectate (intervention group, n=8) or three sham injectates (control group, n=8) via their perineural catheters in the postanesthesia care unit (PACU). Primary outcome measures were the effects on ipsilateral hemidiaphragmatic paralysis, and secondary outcome measures included PACU opioid consumption, pain scores and change in brachial plexus sensory examination and motor function.

Results There was no significant difference in reversal of hemidiaphragmatic paralysis. However, there was a greater number of patients in the intervention group who ultimately displayed partial, as opposed to full, paralysis of the hemidiaphragm (p=0.03). There was no significant difference in pain scores, PACU opioid requirement, and brachial plexus motor and sensory examinations between the two groups.

Conclusions All patients had persistent hemidiaphragmatic paralysis after the intervention, but fewer patients in the intervention group progressed to full paralysis, suggesting that a larger bolus dose of normal saline may be needed to completely reverse hemidiaphragmatic paralysis. Although normal saline injectate in 10mL increments given through the interscalene nerve block catheter had no clinically significant effect on reversing phrenic nerve blockade, it also did not lead to a reduction in analgesia and may be protective in preventing the progression to full hemidiaphragmatic paralysis.

Trail registration number NCT03677778.

  • regional anesthesia
  • nerve block
  • postoperative complications

https://doi.org/10.1136/rapm-2020-101922

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    Footnotes

    • Twitter @lynn_n_gerber, @drcostouros, @janboublikMDPhD, @hornjl, @bantsui

    • Presented at American Society of Regional Anesthesia (ASRA) 2020: Best of Meeting Fellow Travel Award.

    • Contributors LNG: This author conceived, drafted, contributed, revised, approved and is accountable for the final manuscript. LYS: This author contributed, revised, approved and is accountable for the final manuscript. WM: This author contributed, approved and is accountable for the final manuscript. SB: This author contributed, revised, approved and is accountable for the final manuscript. NG: This author contributed, revised, approved and is accountable for the final manuscript. JC: This author contributed, approved and is accountable for the final manuscript. EC: This author contributed, approved and is accountable for the final manuscript. JB This author contributed, approved and is accountable for the final manuscript. J-LH. This author contributed, approved and is accountable for the final manuscript. BCHT. This author conceived, drafted, contributed, revised, approved, supervised and is accountable for the final manuscript.

    • Funding Support was provided solely by funding from the Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University.

    • Disclaimer Normal saline injectate via the interscalene nerve block catheter does not reverse hemidiaphragmatic paralysis due to phrenic nerve blockade, but it may prevent progression to full hemidiaphragmatic paralysis without affecting analgesia.

    • Competing interests None declared.

    • Patient consent for publication Not required.

    • Ethics approval Institutional Review Board (IRB, Stanford Health Care) approval was obtained for this single-institution, randomized and double-blinded study.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data availability statement All data relevant to the study are included in the article or uploaded as online supplemental information. N/A.