Introduction Prolonged tourniquet inflation during surgery frequently leads to tourniquet hypertension (TH), which is thought to arise from compression of A-δ fibers leading to sympathetically mediated C fiber activation. In the lower extremity, C fibers and other sympathetic nerve fibers are carried along the femoral artery. We hypothesized that blockade of these fibers at the femoral artery would decrease the incidence of TH.
Methods Thirty American Society of Anesthesia 1–3 patients aged 18–75 undergoing total ankle arthroplasty were randomized to receive 15 mL of injectate (mepivacaine 1.5% or saline placebo) at the anteromedial aspect of the common femoral artery at the level of the inguinal crease under ultrasound guidance. Both groups received preoperative popliteal sciatic and saphenous nerve blocks for analgesia and a standardized general anesthetic. Esmolol was administered if systolic blood pressure rose >30% above baseline. Incidence of TH was the primary outcome.
Results TH was present in 93.3% of sham patients versus 33.3% of block patients. Mean systolic pressure at 120 min and 150 min of tourniquet time was significantly higher in the sham group compared with the block group. Esmolol requirement (95.3+107.6 v 8.0+14.2, p=<0.001) was also significantly higher in the sham group. No differences were noted in pain scores or opioid consumption, and no patient experienced sensory or motor block of the femoral nerve.
Discussion Under these experimental conditions, injection of local anesthetic around the femoral artery reduced the incidence of TH and intraoperative esmolol requirement.
Trial registration number www.clinicaltrials.gov (NCT03390426; December 28, 2017).
- lower extremity
- ambulatory care
- autonomic nerve block
- nerve block
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Contributors Project was conceived by SAG, WMB, and JG. IRB was prepared by WMB and CW. Data collected and analyzed by CW, MTR, and WMB. Manuscript written by CW, SAG, JG, MTR, and WMB.
Funding This manuscript was supported by the Department of Anesthesiology at Duke University Medical Center.
Competing interests SAG reports other from SPR Therapeutics, personal fees from B. Braun, outside the submitted work; JG reports grants and personal fees from Pacira Biosciences, grants from Mallinckrodt Pharmaceuticals, outside the submitted work; WMB reports personal fees from Pacira Biosciences, outside the submitted work.
Patient consent for publication Not required.
Ethics approval This study was approved by the Duke University Hospital Institutional Review Board (Pro00089161), with patient enrollment beginning on May 18, 2018.
Data availability statement Data are available upon reasonable request. All data relevant to the study are included in the article or uploaded as supplementary information. Data is stored on a secure Duke REDCap database (https://redcap.duke.edu/redcap/)