Updates in our understanding of local anaesthetic systemic toxicity: a narrative review

Abstract

Summary Despite advances in clinical practice, local anaesthetic systemic toxicity continues to occur with the therapeutic use of local anaesthesia. Patterns of presentation have evolved over recent years due in part to the increasing use of ultrasound which has been demonstrated to reduce risk. Onset of toxicity is increasingly delayed, a greater proportion of clinical reports are secondary to fascial plane blocks, and cases are increasing where non‐anaesthetist providers are involved. The evolving clinical context presents a challenge for diagnosis and requires education of all physicians, nurses and allied health professionals about these changing patterns and risks. This review discusses: mechanisms; prevention; diagnosis; and treatment of local anaesthetic systemic toxicity. The local anaesthetic and dose used, site of injection and block conduct and technique are all important determinants of local anaesthetic systemic toxicity, as are various patient factors. Risk mitigation is discussed including the care of at‐risk groups, such as: those at the extremes of age; patients with cardiac, hepatic and specific metabolic diseases; and those who are pregnant. Advances in the changing clinical landscape with novel applications and settings for the use of local anaesthesia are also described. Finally, we signpost future directions to potentially improve the management of local anaesthetic systemic toxicity. The utility of local anaesthetics remains unquestionable in clinical practice, and thus maximising the safe and appropriate use of these drugs should translate to improvements in patient care.

Updates on Wound Infiltration Use for Postoperative Pain Management: A Narrative Review

“…Whenever WI is combined with regional anesthesia, it is important to carefully calculate the total safe dose of LA in order to reduce the risk of toxicity. The incidence of local anesthetic systemic toxicity after subcutaneous infiltration is 11%, and other resources discuss more on this topic [55]. It is vital to limit the LA dose based on patient ideal body weight (IBW) [56] and risk factors (age, lower muscle mass, lower ejection fraction, liver and renal insufficiency, and metabolic disorders) [55].…”

“…The incidence of local anesthetic systemic toxicity after subcutaneous infiltration is 11%, and other resources discuss more on this topic [55]. It is vital to limit the LA dose based on patient ideal body weight (IBW) [56] and risk factors (age, lower muscle mass, lower ejection fraction, liver and renal insufficiency, and metabolic disorders) [55]. Intralipid availability is mandatory for immediate use "at the first signs" of LAST, together with resuscitation equipment and benzodiazepines [37].…”

“…Intralipid availability is mandatory for immediate use "at the first signs" of LAST, together with resuscitation equipment and benzodiazepines [37]. Although bupivacaine has higher potential for cardiac toxicity compared to lidocaine, lidocaine is more frequently involved in LAST [55]. In our practice, surgeons are reluctant to give lidocaine without previous dosage calculation, especially to top up regional blocks with WI.…”

Lido-OH, a Hydroxyl Derivative of Lidocaine, Produced a Similar Local Anesthesia Profile as Lidocaine With Reduced Systemic Toxicities

“…With the strategies such as ultrasound-guided technique, limitation of total drug dose, and co-application of vessel constrictors, the incidence of LAST seems to have decreased to a clinically non-important level, but is by no means unignorable ( Gitman and Barrington, 2018 ) ( Macfarlane et al, 2021 ) In addition, it is now more and more popular to use intravenous local anesthetics for intra-operative analgesia and chronic pain control ( Vanstone and Rockett, 2016 ; Weibel et al, 2016 ; Song et al, 2017 ; Farahmand et al, 2018 ; Soto et al, 2018 ; Clivio et al, 2019 ), however, it may increase the incidence of LAST, because plasm drug concentration would increase more rapidly than local application ( Gitman et al, 2019 ; Torp and Simon, 2020 ). A fundamental method to increase the safety of local anesthetics is to ensure that even if all drugs applied are accidentally injected into the circulation system, there could be a margin wide enough from the actual plasma concentration to the concentration responsible for the earliest toxicities.…”

Perioperative Intravenous Lidocaine and Metastatic Cancer Recurrence - A Narrative Review

“…In addition, as recently proposed, adoption of institutional guidelines regarding administration, monitoring, detection and treatment of systemic toxicity appears prudent wherever i.v. lidocaine is administered, and training of all involved staff should be mandatory ( 178 ). Perhaps, as recently suggested by Pandit and McGuire, use of intravenous lidocaine is currently best confined to subjects participating in clinical trials (including VAPOR-C) under rigorous safety conditions and where the results of usage can contribute to establishing definitive evidence of clinical benefits or otherwise ( 179 ).…”