Complications of Regional Anesthesia: Upper and Lower Extremity Blockade

  • Stephen Choi
  • Patrick B. Y. Wong
  • Kristen Gadbois
  • Colin J. L. McCartney

Key Points

  • Nerve injury after peripheral nerve blocks can be due to needle trauma, chemical neurotoxicity, ischemia, or compression.

  • Intraneural needle placement can cause significant injury, either from direct needle trauma or pressure-related ischemia after injection. Although this probably occurred without sequelae prior to the advent of ultrasound-guided regional anesthesia, there is no evidence to support deliberate intraneural injection. On the contrary, current guidelines recommend utmost care should be taken to avoid accidental intraneural needle placement.

  • The hypothesis that performing peripheral nerve blocks under ultrasound guidance can prevent direct needle injury has not been proven. However, there is evidence to suggest that ultrasound use may decrease the incidence of local anesthetic systemic toxicity (LAST ) for peripheral nerve blocks.

  • Local anesthetics have been shown to have neurotoxic effects during in vitro studies. Although the dose and concentration used in clinical practice is generally safe, it is prudent to use the lowest concentration possible to achieve the desired effect.

  • After peripheral nerve block temporary neurologic deficits may occur in 3 % of patients with most symptoms resolving within days or weeks of surgery. Permanent injury is rare, occurring on average 2.4 instances per 10,000 blocks.

  • Practitioners must be familiar with the potential complications specific to each nerve block prior to performance.


Intraneural Needle trauma Chemical neurotoxicity Compression Neurologic deficits 


  1. 1.
    Brull R, McCartney CJ, Chan VW, El-Beheiry H. Neurological complications after regional anesthesia: contemporary estimates of risk. Anesth Analg. 2007;104:965–74.CrossRefPubMedGoogle Scholar
  2. 2.
    Cope RW. The Woolley and Roe case. 1954. Anaesthesia. 1995;50:162–73.CrossRefPubMedGoogle Scholar
  3. 3.
    Kennedy F, Effron AS, Perry G. The grave spinal cord paralyses caused by spinal anesthesia. Surg Gynecol Obstet. 1950;91:385–98.PubMedGoogle Scholar
  4. 4.
    Dripps RD, Vandam LD. Long-term follow-up of patients who received 10,098 spinal anesthetics: failure to discover major neurological sequelae. J Am Med Assoc. 1954;156:1486–91.CrossRefPubMedGoogle Scholar
  5. 5.
    Hadzic A, Dilberovic F, Shah S, Kulenovic A, Kapur E, Zaciragic A, Cosovic E, Vuckovic I, Divanovic KA, Mornjakovic Z, Thys DM, Santos AC. Combination of intraneural injection and high injection pressure leads to fascicular injury and neurologic deficits in dogs. Reg Anesth Pain Med. 2004;29:417–23.CrossRefPubMedGoogle Scholar
  6. 6.
    Selander D, Dhuner KG, Lundborg G. Peripheral nerve injury due to injection needles used for regional anesthesia. An experimental study of the acute effects of needle point trauma. Acta Anaesthesiol Scand. 1977;21:182–8.CrossRefPubMedGoogle Scholar
  7. 7.
    Rice AS, McMahon SB. Peripheral nerve injury caused by injection needles used in regional anaesthesia: influence of bevel configuration, studied in a rat model. Br J Anaesth. 1992;69:433–8.CrossRefPubMedGoogle Scholar
  8. 8.
    Barrington MJ, Watts SA, Gledhill SR, Thomas RD, Said SA, Snyder GL, Tay VS, Jamrozik K. Preliminary results of the Australasian Regional Anaesthesia Collaboration: a prospective audit of more than 7000 peripheral nerve and plexus blocks for neurologic and other complications. Reg Anesth Pain Med. 2009;34:534–41.CrossRefPubMedGoogle Scholar
  9. 9.
    Orebaugh SL, Kentor ML, Williams BA. Adverse outcomes associated with nerve stimulator-guided and ultrasound-guided peripheral nerve blocks by supervised trainees: update of a single-site database. Reg Anesth Pain Med. 2012;37:577–82.CrossRefPubMedPubMedCentralGoogle Scholar
  10. 10.
    Johnson ME, Saenz JA, DaSilva AD, Uhl CB, Gores GJ. Effect of local anesthetic on neuronal cytoplasmic calcium and plasma membrane lysis (necrosis) in a cell culture model. Anesthesiology. 2002;97:1466–76.CrossRefPubMedGoogle Scholar
  11. 11.
    Lambert LA, Lambert DH, Strichartz GR. Irreversible conduction block in isolated nerve by high concentrations of local anesthetics. Anesthesiology. 1994;80:1082–93.CrossRefPubMedGoogle Scholar
  12. 12.
    Williams BA, Hough KA, Tsui BY, Ibinson JW, Gold MS, Gebhart GF. Neurotoxicity of adjuvants used in perineural anesthesia and analgesia in comparison with ropivacaine. Reg Anesth Pain Med. 2011;36:225–30.CrossRefPubMedPubMedCentralGoogle Scholar
  13. 13.
    Popping DM, Elia N, Marret E, Wenk M, Tramer MR. Clonidine as an adjuvant to local anesthetics for peripheral nerve and plexus blocks: a meta-analysis of randomized trials. Anesthesiology. 2009;111:406–15.CrossRefPubMedGoogle Scholar
  14. 14.
    Choi S, Rodseth R, McCartney CJ. Effects of dexamethasone as a local anaesthetic adjuvant for brachial plexus block: a systematic review and meta-analysis of randomized trials. Br J Anaesth. 2014;112:427–39.CrossRefPubMedGoogle Scholar
  15. 15.
    Abdallah FW, Dwyer T, Chan VW, Niazi AU, Ogilvie-Harris DJ, Oldfield S, Patel R, Oh J, Brull R. IV and perineural dexmedetomidine similarly prolong the duration of analgesia after interscalene brachial plexus block: a randomized, three-arm, triple-masked, placebo-controlled trial. Anesthesiology. 2016;124:683–95.CrossRefPubMedGoogle Scholar
  16. 16.
    Desmet M, Braems H, Reynvoet M, Plasschaert S, Van Cauwelaert J, Pottel H, Carlier S, Missant C, Van de Velde M. I.V. and perineural dexamethasone are equivalent in increasing the analgesic duration of a single-shot interscalene block with ropivacaine for shoulder surgery: a prospective, randomized, placebo-controlled study. Br J Anaesth. 2013;111:445–52.CrossRefPubMedGoogle Scholar
  17. 17.
    Upton AR, McComas AJ. The double crush in nerve entrapment syndromes. Lancet. 1973;2:359–62.CrossRefPubMedGoogle Scholar
  18. 18.
    Chan VW, Brull R, McCartney CJ, Xu D, Abbas S, Shannon P. An ultrasonographic and histological study of intraneural injection and electrical stimulation in pigs. Anesth Analg. 2007;104:1281–4. tablesCrossRefPubMedGoogle Scholar
  19. 19.
    Auroy Y, Benhamou D, Bargues L, Ecoffey C, Falissard B, Mercier FJ, Bouaziz H, Samii K. Major complications of regional anesthesia in France: The SOS Regional Anesthesia Hotline Service. Anesthesiology. 2002;97:1274–80.CrossRefPubMedGoogle Scholar
  20. 20.
    Neal JM, Hebl JR, Gerancher JC, Hogan QH. Brachial plexus anesthesia: essentials of our current understanding. Reg Anesth Pain Med. 2002;27:402–28.CrossRefPubMedGoogle Scholar
  21. 21.
    DeHart MM, Riley Jr LH. Nerve injuries in total hip arthroplasty. J Am Acad Orthop.Surg. 1999;7:101–11.CrossRefPubMedGoogle Scholar
  22. 22.
    Robards C, Hadzic A, Somasundaram L, Iwata T, Gadsden J, Xu D, Sala-Blanch X. Intraneural injection with low-current stimulation during popliteal sciatic nerve block. Anesth Analg. 2009;109:673–7.CrossRefPubMedGoogle Scholar
  23. 23.
    Macaire P, Singelyn F, Narchi P, Paqueron X. Ultrasound- or nerve stimulation-guided wrist blocks for carpal tunnel release: a randomized prospective comparative study. Reg Anesth Pain Med. 2008;33:363–8.PubMedGoogle Scholar
  24. 24.
    Bigeleisen PE. Nerve puncture and apparent intraneural injection during ultrasound-guided axillary block does not invariably result in neurologic injury. Anesthesiology. 2006;105:779–83.CrossRefPubMedGoogle Scholar
  25. 25.
    Lupu CM, Kiehl TR, Chan VW, El-Beheiry H, Madden M, Brull R. Nerve expansion seen on ultrasound predicts histologic but not functional nerve injury after intraneural injection in pigs. Reg Anesth Pain Med. 2010;35:132–9.CrossRefPubMedGoogle Scholar
  26. 26.
    Tsui BC, Pillay JJ, Chu KT, Dillane D. Electrical impedance to distinguish intraneural from extraneural needle placement in porcine nerves during direct exposure and ultrasound guidance. Anesthesiology. 2008;109:479–83.CrossRefPubMedGoogle Scholar
  27. 27.
    Sites BD, Taenzer AH, Herrick MD, Gilloon C, Antonakakis J, Richins J, Beach ML. Incidence of local anesthetic systemic toxicity and postoperative neurologic symptoms associated with 12,668 ultrasound-guided nerve blocks: an analysis from a prospective clinical registry. Reg Anesth Pain Med. 2012;37:478–82.CrossRefPubMedGoogle Scholar
  28. 28.
    Thomas SE, Winchester JB, Hickman G, DeBusk E. A confirmed case of injury to the long thoracic nerve following a posterior approach to an interscalene nerve block. Reg Anesth Pain Med. 2013;38:370.CrossRefPubMedGoogle Scholar
  29. 29.
    Sinha SK, Abrams JH, Barnett JT, Muller JG, Lahiri B, Bernstein BA, Weller RS. Decreasing the local anesthetic volume from 20 to 10 mL for ultrasound-guided interscalene block at the cricoid level does not reduce the incidence of hemidiaphragmatic paresis. Reg Anesth Pain Med. 2011;36:17–20.CrossRefPubMedGoogle Scholar
  30. 30.
    Lee JH, Cho SH, Kim SH, Chae WS, Jin HC, Lee JS, Kim YI. Ropivacaine for ultrasound-guided interscalene block: 5 mL provides similar analgesia but less phrenic nerve paralysis than 10 mL. Can J Anaesth. 2011;58:1001–6.CrossRefPubMedGoogle Scholar
  31. 31.
    Riazi S, Carmichael N, Awad I, Holtby RM, McCartney CJ. Effect of local anaesthetic volume (20 vs 5 ml) on the efficacy and respiratory consequences of ultrasound-guided interscalene brachial plexus block. Br J Anaesth. 2008;101:549–56.CrossRefPubMedGoogle Scholar
  32. 32.
    Perlas A, Lobo G, Lo N, Brull R, Chan VW, Karkhanis R. Ultrasound-guided supraclavicular block: outcome of 510 consecutive cases. Reg Anesth Pain Med. 2009;34:171–6.CrossRefPubMedGoogle Scholar
  33. 33.
    Bhatia A, Lai J, Chan VW, Brull R. Case report: pneumothorax as a complication of the ultrasound-guided supraclavicular approach for brachial plexus block. Anesth Analg. 2010;111:817–9.CrossRefPubMedGoogle Scholar
  34. 34.
    Gauss A, Tugtekin I, Georgieff M, Dinse-Lambracht A, Keipke D, Gorsewski G. Incidence of clinically symptomatic pneumothorax in ultrasound-guided infraclavicular and supraclavicular brachial plexus block. Anaesthesia. 2014;69:327–36.CrossRefPubMedGoogle Scholar
  35. 35.
    Lecours M, Levesque S, Dion N, Nadeau MJ, Dionne A, Turgeon AF. Complications of single-injection ultrasound-guided infraclavicular block: a cohort study. Can J Anaesth. 2013;60:244–52.CrossRefPubMedGoogle Scholar
  36. 36.
    Pousman RM, Mansoor Z, Sciard D. Total spinal anesthetic after continuous posterior lumbar plexus block. Anesthesiology. 2003;98:1281–2.CrossRefPubMedGoogle Scholar
  37. 37.
    Capdevila X, Macaire P, Dadure C, Choquet O, Biboulet P, Ryckwaert Y, D’Athis F. Continuous psoas compartment block for postoperative analgesia after total hip arthroplasty: new landmarks, technical guidelines, and clinical evaluation. Anesth Analg. 2002;94:1606–13. tableCrossRefPubMedGoogle Scholar
  38. 38.
    Capdevila X, Coimbra C, Choquet O. Approaches to the lumbar plexus: success, risks, and outcome. Reg Anesth Pain Med. 2005;30:150–62.PubMedGoogle Scholar
  39. 39.
    Capdevila X, Pirat P, Bringuier S, Gaertner E, Singelyn F, Bernard N, Choquet O, Bouaziz H, Bonnet F. Continuous peripheral nerve blocks in hospital wards after orthopedic surgery: a multicenter prospective analysis of the quality of postoperative analgesia and complications in 1,416 patients. Anesthesiology. 2005;103:1035–45.CrossRefPubMedGoogle Scholar
  40. 40.
    Bernstein IT, Hansen BJ. Iatrogenic psoas abscess. Case report. Scand J Urol Nephrol. 1991;25:85–6.CrossRefPubMedGoogle Scholar
  41. 41.
    Klein SM, D’Ercole F, Greengrass RA, Warner DS. Enoxaparin associated with psoas hematoma and lumbar plexopathy after lumbar plexus block. Anesthesiology. 1997;87:1576–9.CrossRefPubMedGoogle Scholar
  42. 42.
    Horlocker TT, Wedel DJ, Rowlingson JC, Enneking FK, Kopp SL, Benzon HT, Brown DL, Heit JA, Mulroy MF, Rosenquist RW, Tryba M, Yuan CS. Regional anesthesia in the patient receiving antithrombotic or thrombolytic therapy: American Society of Regional Anesthesia and Pain Medicine Evidence-Based Guidelines (Third Edition). Reg Anesth Pain Med. 2010;35:64–101.CrossRefPubMedGoogle Scholar
  43. 43.
    Weller RS, Gerancher JC, Crews JC, Wade KL. Extensive retroperitoneal hematoma without neurologic deficit in two patients who underwent lumbar plexus block and were later anticoagulated. Anesthesiology. 2003;98:581–5.CrossRefPubMedGoogle Scholar
  44. 44.
    Bickler P, Brandes J, Lee M, Bozic K, Chesbro B, Claassen J. Bleeding complications from femoral and sciatic nerve catheters in patients receiving low molecular weight heparin. Anesth Analg. 2006;103:1036–7.CrossRefPubMedGoogle Scholar
  45. 45.
    Cuvillon P, Ripart J, Lalourcey L, Veyrat E, L’hermite J, Boisson C, Thouabtia E, Eledjam JJ. The continuous femoral nerve block catheter for postoperative analgesia: bacterial colonization, infectious rate and adverse effects. Anesth Analg. 2001;93:1045–9.CrossRefPubMedGoogle Scholar
  46. 46.
    Feibel RJ, Dervin GF, Kim PR, Beaule PE. Major complications associated with femoral nerve catheters for knee arthroplasty: a word of caution. J Arthroplasty. 2009;24:132–7.CrossRefPubMedGoogle Scholar
  47. 47.
    Sharma S, Iorio R, Specht LM, Davies-Lepie S, Healy WL. Complications of femoral nerve block for total knee arthroplasty. Clin Orthop Relat Res. 2010;468:135–40.CrossRefPubMedGoogle Scholar
  48. 48.
    Mizner RL, Petterson SC, Stevens JE, Vandenborne K, Snyder-Mackler L. Early quadriceps strength loss after total knee arthroplasty. The contributions of muscle atrophy and failure of voluntary muscle activation. J Bone Joint Surg Am. 2005;87:1047–53.CrossRefPubMedPubMedCentralGoogle Scholar
  49. 49.
    Stevens JE, Mizner RL, Snyder-Mackler L. Quadriceps strength and volitional activation before and after total knee arthroplasty for osteoarthritis. J Orthop Res. 2003;21:775–9.CrossRefPubMedGoogle Scholar
  50. 50.
    Memtsoudis SG, Danninger T, Rasul R, Poeran J, Gerner P, Stundner O, Mariano ER, Mazumdar M. Inpatient falls after total knee arthroplasty: the role of anesthesia type and peripheral nerve blocks. Anesthesiology. 2014;120:551–63.CrossRefPubMedGoogle Scholar
  51. 51.
    Chen J, Lesser JB, Hadzic A, Reiss W, Resta-Flarer F. Adductor canal block can result in motor block of the quadriceps muscle. Reg Anesth Pain Med. 2014;39:170–1.CrossRefPubMedGoogle Scholar
  52. 52.
    Veal C, Auyong DB, Hanson NA, Allen CJ, Strodtbeck W. Delayed quadriceps weakness after continuous adductor canal block for total knee arthroplasty: a case report. Acta Anaesthesiol Scand. 2014;58:362–4.CrossRefPubMedGoogle Scholar
  53. 53.
    Jaeger P, Nielsen ZJ, Henningsen MH, Hilsted KL, Mathiesen O, Dahl JB. Adductor canal block versus femoral nerve block and quadriceps strength: a randomized, double-blind, placebo-controlled, crossover study in healthy volunteers. Anesthesiology. 2013;118:409–15.CrossRefPubMedGoogle Scholar
  54. 54.
    Kwofie MK, Shastri UD, Gadsden JC, Sinha SK, Abrams JH, Xu D, Salviz EA. The effects of ultrasound-guided adductor canal block versus femoral nerve block on quadriceps strength and fall risk: a blinded, randomized trial of volunteers. Reg Anesth Pain Med. 2013;38:321–5.CrossRefPubMedGoogle Scholar
  55. 55.
    Gautier PE, Hadzic A, Lecoq JP, Brichant JF, Kuroda MM, Vandepitte C. Distribution of Injectate and Sensory-Motor Blockade After Adductor Canal Block. Anesth Analg. 2016;122:279–82.CrossRefPubMedGoogle Scholar
  56. 56.
    Cheney FW, Domino KB, Caplan RA, Posner KL. Nerve injury associated with anesthesia: a closed claims analysis. Anesthesiology. 1999;90:1062–9.CrossRefPubMedGoogle Scholar
  57. 57.
    Fanelli G, Casati A, Garancini P, Torri G. Nerve stimulator and multiple injection technique for upper and lower limb blockade: failure rate, patient acceptance, and neurologic complications. Study Group on Regional Anesthesia. Anesth Analg. 1999;88:847–52.CrossRefPubMedGoogle Scholar
  58. 58.
    Gaertner E, Fouche E, Choquet O, Hadzic A, Vloka JD. Sciatic nerve block. Textbook of Regional Anesthesia and Acute Pain Management. Hadzic A. McGraw-Hill; 2007.Google Scholar
  59. 59.
    Sala-Blanch X, Ribalta T, Rivas E, Carrera A, Gaspa A, Reina MA, Hadzic A. Structural injury to the human sciatic nerve after intraneural needle insertion. Reg Anesth Pain Med. 2009;34:201–5.CrossRefPubMedGoogle Scholar
  60. 60.
    Blanch XS, AM L, Carazo J, Hadzic A, Carrera A, Pomes J, Valls-Sole J. Intraneural injection during nerve stimulator-guided sciatic nerve block at the popliteal fossa. Br J Anaesth. 2009;102:855–61.CrossRefGoogle Scholar
  61. 61.
    Bier A. Uber einen neuen weg lokalanasthesie an den gliedmassen zu erzeugen. Verh Dtsch Ges Chir. 1908; 37:204–14. Ref Type: Abstract.Google Scholar
  62. 62.
    Kim DD, Shuman C, Sadr B. Intravenous regional anesthesia for outpatient foot and ankle surgery: a prospective study. Orthopedics. 1993;16:1109–13.PubMedGoogle Scholar
  63. 63.
    Brown EM, McGriff JT, Malinowski RW. Intravenous regional anaesthesia (Bier block): review of 20 years’ experience. Can J Anaesth. 1989;36:307–10.CrossRefPubMedGoogle Scholar
  64. 64.
    Guay J. Adverse events associated with intravenous regional anesthesia (Bier block): a systematic review of complications. J Clin Anesth. 2009;21:585–94.CrossRefPubMedGoogle Scholar
  65. 65.
    Quinton DN, Hughes J, Mace PF, Aitkenhead AR. Prilocaine leakage during tourniquet inflation in intravenous regional anaesthesia: the influence of fracture manipulation. Injury. 1988;19:333–5.CrossRefPubMedGoogle Scholar
  66. 66.
    Lawes EG, Johnson T, Pritchard P, Robbins P. Venous pressures during simulated Bier’s block. Anaesthesia. 1984;39:147–9.CrossRefPubMedGoogle Scholar
  67. 67.
    Davies JA, Walford AJ. Intravenous regional anaesthesia for foot surgery. Acta Anaesthesiol Scand. 1986;30:145–7.CrossRefPubMedGoogle Scholar
  68. 68.
    Clarkson CW, Hondeghem LM. Mechanism for bupivacaine depression of cardiac conduction: fast block of sodium channels during the action potential with slow recovery from block during diastole. Anesthesiology. 1985;62:396–405.CrossRefPubMedGoogle Scholar
  69. 69.
    Schurg R, Biscoping J, Bachmann M, Hempelmann G. Intravenous regional anesthesia of the foot using prilocaine. Clinical aspects, pharmacokinetic and pharmacodynamic studies. Reg Anaesth. 1990;13:118–21.PubMedGoogle Scholar
  70. 70.
    Armstrong P, Power I, Wildsmith JA. Addition of fentanyl to prilocaine for intravenous regional anaesthesia. Anaesthesia. 1991;46:278–80.CrossRefPubMedGoogle Scholar
  71. 71.
    Arthur JM, Heavner JE, Mian T, Rosenberg PH. Fentanyl and lidocaine versus lidocaine for Bier block. Reg Anesth. 1992;17:223–7.PubMedGoogle Scholar
  72. 72.
    Kleinschmidt S, Stockl W, Wilhelm W, Larsen R. The addition of clonidine to prilocaine for intravenous regional anaesthesia. Eur J Anaesthesiol. 1997;14:40–6.CrossRefPubMedGoogle Scholar
  73. 73.
    Dunbar RW, Mazze RI. Intravenous regional anesthesia: experience with 779 cases. Anesth Analg. 1967;46:806–13.CrossRefPubMedGoogle Scholar
  74. 74.
    Plourde G, Barry PP, Tardif L, Lepage Y, Hardy JF. Decreasing the toxic potential of intravenous regional anaesthesia. Can J Anaesth. 1989;36:498–502.CrossRefPubMedGoogle Scholar
  75. 75.
    El-Hassan KM, Hutton P, Black AM. Venous pressure and arm volume changes during simulated Bier’s block. Anaesthesia. 1984;39:229–35.CrossRefPubMedGoogle Scholar
  76. 76.
    Kalman S, Linderfalk C, Wardell K, Eintrei C, Lisander B. Differential effect on vasodilatation and pain after intradermal capsaicin in humans during decay of intravenous regional anesthesia with mepivacaine. Reg Anesth Pain Med. 1998;23:402–8.PubMedGoogle Scholar
  77. 77.
    Sukhani R, Garcia CJ, Munhall RJ, Winnie AP, Rodvold KA. Lidocaine disposition following intravenous regional anesthesia with different tourniquet deflation technics. Anesth Analg. 1989;68:633–7.PubMedGoogle Scholar
  78. 78.
    Song L, Wu C, Liu J, Zuo Y, Volinn E, Yao J. Potential advantages of an additional forearm rubber tourniquet in intravenous regional anesthesia: a randomized clinical trial. J Anesth. 2015;29:551–6.CrossRefPubMedGoogle Scholar
  79. 79.
    Arslanian B, Mehrzad R, Kramer T, Kim DC. Forearm Bier block: a new regional anesthetic technique for upper extremity surgery. Ann Plast Surg. 2014;73:156–7.PubMedGoogle Scholar
  80. 80.
    Larsen UT, Hommelgaard P. Pneumatic tourniquet paralysis following intravenous regional analgesia. Anaesthesia. 1987;42:526–8.CrossRefPubMedGoogle Scholar
  81. 81.
    Perlas A, Peng PW, Plaza MB, Middleton WJ, Chan VW, Sanandaji K. Forearm rescue cuff improves tourniquet tolerance during intravenous regional anesthesia. Reg Anesth Pain Med. 2003;28:98–102.CrossRefPubMedGoogle Scholar

Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  • Stephen Choi
    • 1
  • Patrick B. Y. Wong
    • 2
  • Kristen Gadbois
    • 2
  • Colin J. L. McCartney
    • 2
  1. 1.Department of AnesthesiaSunnybrook Health Sciences Centre, University of TorontoTorontoCanada
  2. 2.Department of Anesthesiology and Pain MedicineUniversity of OttawaOttawaCanada

Personalised recommendations