Local anaesthetic toxicity during an awake tracheal intubation course

Modified anterior approach versus traditional posterior approach for ultrasound-guided superior laryngeal nerve block in awake endotracheal intubation: a randomized non-inferiority clinical trial

STUDY OBJECTIVE

This study was undertaken to compare the effect of the modified ultrasound-guided anterior superior laryngeal nerve block (SLNB) with the traditional ultrasound-guided posterior SLNB in providing intubation conditions during awake tracheal intubation (ATI) in patients without difficult airway.

DESIGN

Randomized, assessor-blind. Registration number: ChiCTR2200058086.

SETTING

West China Hospital of Sichuan University, Chengdu, China.

PATIENTS

104 patients aged 18-65 years, of American Society of Anesthesiologists status I-III, posted for elective general surgery with general endotracheal anesthesia.

INTERVENTIONS

The patients were randomized into two groups (modified group, n = 52; traditional group, n = 52). Modified anterior SLNB or traditional posterior SLNB was performed under ultrasound guidance.

MEASUREMENTS

The primary outcome was the proportion of acceptable intubation condition (AIC), which was analyzed in both per-protocol (PP) and intention-to-treat (ITT) populations. The prespecified non-inferiority margin was -4.8%. Secondary outcomes included intubation success rate on the first attempt, hemodynamic parameters during ATI, time taken for airway anesthesia and intubation, recall of intubation, patient perception of comfort, and incidence and severity of postoperative complications.

MAIN RESULTS

In the PP population, the proportion of AIC in the modified group was 49/49 (100%) and that in the traditional group was 49/49 (100%), absolute difference 0, lower limit of 1-sided 95% CI, -0.3%. In the ITT population, the primary outcomes in the modified and traditional group were 52/52 (100%) and 51/52 (98.1%), respectively, with an absolute difference of 1.9% and a lower limit of 1-sided 95% CI of -1.2%. The non-inferiority of modified ultrasound-guided anterior SLNB was confirmed in both populations.

CONCLUSIONS

Among adults without difficult airways during videolaryngoscope-assisted ATI, the modified ultrasound-guided anterior SLNB, compared to the traditional posterior approach, showed a statistically non-inferior effect in terms of providing AIC.

Airway nerve blocks for awake tracheal intubation: A meta-analysis of randomized control trials and trial sequential analysis

STUDY OBJECTIVE

This systematic review and meta-analysis aimed to assess the superiority of airway nerve blocks versus airway anesthesia without nerve blocks for awake tracheal intubation (ATI).

DESIGN

Systematic review and meta-analysis of randomized controlled trials (RCTs).

SETTING

All studies that assessed the superiority of airway anesthesia technique for awake tracheal intubation were searched in PubMed, Web of Science, Cochrane Library, Ovid Medline, Embase and Chinese databases (including China National Knowledge Infrastructure, Wanfang database, and VIP databases) and trial registry databases from their inception to December 2022.

PATIENTS

Adult patients included in randomized controlled trials comparing airway anesthesia with or without airway nerve blocks for ATI.

INTERVENTIONS

Airway nerve (including superior laryngeal nerve, glossopharyngeal nerve, or recurrent laryngeal nerve) blocks for ATI.

MEASUREMENTS

The primary outcome was the intubation time. Secondary outcomes were quality of intubating conditions (including patient reaction to placement of the flexible scope and tracheal tube, coughing and gagging, and patient satisfaction) and overall complications during ATI.

MAIN RESULTS

Fourteen articles with 658 patients were identified for analysis. When compared with airway anesthesia without nerve blocks, airway nerve blocks significantly reduced intubation time (standardized mean difference [SMD] -2.57, 95% CI -3.59- -1.56, p < 0.00001), improved anesthesia quality of ATI with higher no reaction to placement of the flexible scope and tracheal tube (relative risk [RR] 9.87; 95% CI 4.10-23.75, p < 0.00001), lower cough or gag reflex during intubation (RR 0.35, 95% CI 0.27-0.46, p < 0.00001), higher excellent patient satisfaction rate (RR 1.88, 95% CI 1.05-3.34, p = 0.03), and lower overall complications (RR 0.29, 95% CI 0.19-0.45, p < 0.00001). The overall quality of evidence was moderate.

CONCLUSIONS

Based on current published evidence, airway nerve blocks provide better airway anesthesia quality for ATI with a shorter intubation time, better intubation conditions including higher no reaction to placement of the flexible scope and tracheal tube, lower cough or gag reflex during intubation, higher excellent patient satisfaction, and lower overall complications.

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

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.