Equis ISSN 2398-2977

Peri-operative lidocaine infusion: IV

Contributor(s): Craig Johnson, Joanna Murrell

Introduction

  • A large multi-centered epidemiological study investigating peri-operative equine fatalities, demonstrated a significantly higher peri-operative mortality rate in horses, compared to small animals and humans. The reasons for the high incidence of deaths have not been fully elucidated, however limitations in current equine anesthetic techniques are almost certainly a contributing factor.
  • In horses, anesthesia is commonly maintained using high concentrations of volatile agents that have significant depressant effects on the equine cardiovascular (CVS) system.
  • In man and small animals multi-modal techniques have evolved:
    • Anesthesia is maintained with a combination of intravenous and volatile agents.
    • These techniques combine anesthetic agents with different specific actions to provide unconsciousness, muscle relaxation and analgesia.
    • This enables the dose of each individual agent to be reduced and minimizes adverse side effects, particularly on the cardiovascular system.
  • In man potent opioids are an integral part of the anesthetic protocol, providing analgesia throughout surgery with minimal cardiovascular side effects.
  • Unfortunately potent opioids have excitatory side effects in horses that render them problematic for clinical use. Limb fracture is relatively common during stormy recoveries from anesthesia in the horse. Horses that attempt to stand early in the recovery period, when ataxic, are obviously at greater risk. There could be many explanations for this agitation, however peri-operative pain is probably a significant factor. Current equine anesthetic protocols provide poor peri-operative analgesia compared to those used in man and small animals.
  • Therefore, incorporation of an intravenous agent that provides peri-operative analgesia and reduces the concentration of volatile agent required to maintain anesthesia into anesthetic regimens, may have significant advantages.
  • Lidocaine   Lidocaine  , administered by continuous IV infusion (systemically), appears to provide both analgesia and a volatile agent sparing effect. Currently studies investigating the use of lidocaine by infusion during anesthesia, in horses and other species, are limited. However the results appear to be promising, with systemic lidocaine providing improved peri-operative analgesia with minimal cardiovascular side effects.

Studies in man

  • Intravenous lidocaine has been used peri-operatively in man as a supplement to general anesthesia.
  • More recently systemic lidocaine has been administered to treat chronic pain, particularly pain of neuropathic origin.

Studies in horses

  • Systemic administration of lidocaine during anesthesia in horses has undergone limited evaluation.
  • One study investigated the effect of intravenous lidocaine on the minimum alveolar concentration (MAC) of halothane:
    • Lidocaine decreased MAC of halothane in a dose dependent manner, demonstrating a halothane-sparing effect.
    • Plasma concentrations of lidocaine administered at two different infusion rates (low and high) were measured. Concentrations varied between 1-3 ug/ml and 3-7 ug/ml respectively <2 h after the start of the infusion, suggesting that the lidocaine concentration gradually increased with time.
  • Another study used EEG changes as a marker for nociception (pain) during anesthesia and surgery to investigate the antinociceptive (analgesic) effects of intravenous lidocaine as an adjunct to halothane anesthesia in ponies during castration; lidocaine abolished EEG changes during castration suggesting an analgesic action.
  • In both of these investigations the infusion of lidocaine was associated with good CVS stability. These studies highlight the potential for systemic lidocaine to be incorporated into clinical equine anesthetic protocols.

Mechanism of action

  • Lidocaine hydrochloride is a widely used local anesthetic agent. Local anesthetic agents applied directly to nerve fibers block conduction of action potentials by modifying sodium channels in the cell membrane.
  • The mechanisms whereby systemic lidocaine exerts an analgesic action have not been fully elucidated. Both peripheral and central sites of action have been proposed.
  • Peripherally, lidocaine analgesia may result from specific peripheral blockade of ectopic discharges in neurones involved in nociception. A direct action of lidocaine on spinal transmission in the spinal cord has also been suggested, although the cellular mechanism of such a spinal action is not clear.
  • The relationship between plasma lidocaine concentration and analgesic efficacy in man has been determined and suggests that there may be a divergence in the specificity of the analgesic action of systemic lidocaine according to the nature of the pain inducing process.
  • It appears that low concentrations of lidocaine are effective at suppressing neuropathic pain, while higher concentrations suppress both neuropathic and ischemic pain, eg pain produced by a tourniquet placed around the arm.
  • The greater efficacy of systemic lidocaine, against neuropathic pain, may reflect the changes in neuronal sodium channels that occur in chronic pain states.

Uses

  • Lidocaine   Lidocaine  can be administered continuously by IV infusion as an adjunct to maintenance of anesthesia with volatile agents (such as halothane   Halothane  or isoflurane   Isoflurane  ). Two infusion regimens have been described:
    • 5 mg/kg-1 lidocaine loading dose, 100 ug/kg/min-1 continuous intravenous infusion (HIGH DOSE).
    • 2.5 mg/kg-1 lidocaine loading dose, 50 ug/kg/min-1 continuous intravenous infusion (LOW DOSE).
  • The loading dose of lidocaine is administered slowly over 15 min.

Advantages

  • Improved peri-operative analgesia.
  • Reduction in the concentration of volatile agent needed to maintain anesthesia (decreased CVS side effects).
  • Good CVS stability during the lidocaine infusion.

Disadvantages

  • Limited data has been published describing this technique, although anecdotal evidence suggests that the use of lidocaine infusions during anesthesia in horses is increasing.
  • Potential for hypotension during administration of the lidocaine loading dose if it is given too quickly. This can be effectively managed by administration of an inotrope such as dobutamine   Dobutamine  .
  • Although the CVS stability during this technique appears to be good in healthy horses, there are limited data regarding use of the technique in very CVS compromised patients such as horses presented for exploratory laparotomy   Abdomen: laparotomy  .
  • Potential for accumulation of lidocaine if a prolonged infusion is given (>2 h), with a risk of prolonged recovery from anesthesia. After 2 h infusion of the higher dose rate (100 ug/kg/min-1) the infusion rate should be halved (50 ug/kg/min-1).

Requirements

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Procedure

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Aftercare

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Valverde A et al (2010) Comparison of cardiovascular function and quality of recovery in isoflurane-anaesthetised horses administered a constant rate infusion of lidocaine or lidocaine and medetomidine during elective surgery. Equine Vet J 42 (3), 192-199 PubMed.
  • Williams J M et al (2010) Effect of intravenous lidocaine administration on laminar inflammation in the black walnut extract model of laminitis. Equine Vet J 42 (3), 261-269 PubMed.
  • Koppert W, Ostermeirer N, Sittl R, Weidner C & Schmelz M (2000) Low-dose lidocaine reduces secondary hyperalgesia by a central mode of action. Pain 85 (1-2), 217-224 PubMed.
  • Doherty T & Frazier D (1998) Effect of intravenous lidocaine on halothane minimum alveolar concentration in ponies. Equine Vet J 30 (4), 300-303 PubMed.
  • Ferrante F, Paggioli J, Cherukuri S & Arthur G (1996) The analgesic response to intravenous lidocaine in the treatment of neuropathic pain. Anesthesia and Analgesia 82 (1), 91-97 PubMed.
  • Wallace M, Dyck J, Rossi S & Yaksh T (1996) Computer controlled lidocaine infusion for the evaluation of neuropathic pain after peripheral nerve injury. Pain 66 (1), 69-77 PubMed.
  • Waterman A (1996) Equine anesthesia - HBLB workshop. Equine Vet J 28 (1), 10-14 Wiley Online Library.
  • Johnston G, Taylor P & Holmes M (1995) Confidential enquiry of perioperative equine fatalities (CEPEF-1) - Preliminary results. Equine Vet J 27 (3), 193-200 PubMed.
  • Pascoe P, Black W, Claxton J & Sanson R (1991) The pharmacokinetics and locomotor activity of alfentanil in the horse. J Vet Pharmacol Therap 14 (3), 317-325 PubMed.
  • Tanelian D & MacIver M (1991) Analgesic concentrations of lidocaine suppress tonic A-delta and C fiber discharges produced by acute injury. Anesthesiology 74 (5), 934-936 PubMed.
  • Kastrup J, Petersen P, Dejgard A, Angelo H & Hilsted J (1987) Intravenous lidocaine infusion - A new treatment of chronic painful diabetic neuropathy. Pain 28 (1), 69-75 PubMed.
  • Woolf C & Wiesenfeld-Hallin Z (1985) The systemic administration of local anaesthetics produces a selective depression of C-afferent fibre evoked activity in the spinal cord. Pain 23 (4), 361-374 PubMed.
  • Boas R, Covino B & Shahnarian A (1982) Analgesic responses to IV lignocaine. British J Anesthesia 54 (5), 501-505 PubMed.
  • Bartlett E & Hutaserani O (1961) Xylocaine for the relief of postoperative pain. Anesthesia and Analgesia 40, 296-304 PubMed.
  • DeClive-Lowe SD, Desmond J & North J (1958) Intravenous lignocaine anesthesia. Anesthesia 13 (2), 138-146 PubMed.

Other sources of information

  • Murrell J (2001)Spontaneous EEG Changes in the Equine Surgical Patient.In:PhD Thesis. University of Bristol.
  • Taylor P (2000)Is Intravenous Anaesthesia in Horses Better than Volatile Agents?In:Proceedings of the Association of Veterinary Anesthetists - Spring 2000 Conference. Cambridge, UK.


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