The Third American Society of Regional Anesthesia and Pain Medicine Practice Advisory on Local Anesthetic Systemic Toxicity

Abstract

The American Society of Regional Anesthesia and Pain Medicine's Third Practice Advisory on local anesthetic systemic toxicity is an interim update from its 2010 advisory. The advisory focuses on new information regarding the mechanisms of lipid resuscitation, updated frequency estimates, the preventative role of ultrasound guidance, changes to case presentation patterns, and limited information related to local infiltration anesthesia and liposomal bupivacaine. In addition to emerging information, the advisory updates recommendations pertaining to prevention, recognition, and treatment of local anesthetic systemic toxicity. WHAT'S NEW IN THIS UPDATE?: This interim update summarizes recent scientific findings that have enhanced our understanding of the mechanisms that lead to lipid emulsion reversal of LAST, including rapid partitioning, direct inotropy, and post-conditioning. Since the previous practice advisory, epidemiological data have emerged that suggest a lower frequency of LAST as reported by single institutions and some registries, nevertheless a considerable number of events still occur within the general community. Contemporary case reports suggest a trend toward delayed presentation, which may mirror the increased use of ultrasound guidance (fewer intravascular injections), local infiltration techniques (slower systemic uptake), and continuous local anesthetic infusions. Small patient size and sarcopenia are additional factors that increase potential risk for LAST. An increasing number of reported events occur outside of the traditional hospital setting and involve non-anesthesiologists.

Local anesthetic systemic toxicity: current perspectives

“… 46 The American Society of Regional Anesthesia and Pain Medicine guidelines further recommend that dosing should be based on lean body weight. 47 …”

“…Prevention should be the priority for reducing the frequency and severity of LAST. 47 No single intervention eliminates the risk, and therefore, prevention is a multifactorial process.…”

“…This latter measure is still useful despite a false-negative rate of around 2%. 47 Markers such as epinephrine may also mitigate the risk of intravascular injection, where addition of 15 µg⋅mL −1 will increase the heart rate by ≥10 beats per minute or systolic blood pressure by ≥15 mmHg. Practical interventions such as clear labeling of LA-containing syringes and meticulous handling of these syringes may be of benefit.…”

Lipofundin MCT/LCT Inhibits Levcromakalim-Induced Vasodilation by Inhibiting Endothelial Nitric Oxide Release

“…Furthermore, lipid emulsion attenuates the NO-mediated relaxation induced by acetylcholine [11]. This pathophysiological state, including hypotension, acidosis and hypoxia induced by local anaesthetic systemic toxicity, causes K ATP channel-induced vasodilation as a protective response through the attenuation of calcium influx and lipid emulsion has been used to alleviate cardiovascular collapse induced by toxic doses of a local anaesthetic mainly through indirect mechanisms [1,3,12,13]. However, the direct effect of lipid emulsion alone, such as Intralipid and Lipofundin MCT/LCT, on the vasodilation induced by K ATP channels remains to be determined.…”

Regional anesthesia during the COVID-19 pandemic: a time to reconsider practices? (Letter #1)

“…While ultrasound guidance may not decrease the risk of nerve injury, it has been shown to decrease the incidence of LAST by 65%. 5 In addition, a neuraxial anesthetic on an awake (preferably quiet and non-coughing) patient who is wearing a surgical mask may not require continuous capnography monitoring or oxygen supplementation A ; this can be especially useful in cases of shortages of antimicrobial breathing circuit filters or in austere/ resource-poor environments. Furthermore, an awake patient may be transferred to their hospital room with minimal recovery time.…”