Airway topicalization
Myron Yaster MD, Melissa Brooks Peterson MD, and Lynne G. Maxwell MD
Pediatric anesthesiologists provide sedation or anesthesia to children undergoing procedures in which airway topicalization is employed (e.g. microlaryngoscopy/bronchoscopy, bronchoscopy +/- dilation, supraglottoplasty). Though the individual administering the local anesthetic can vary (anesthesiologists, surgeons, pulmonologists being the most common) anesthesiologists are the gatekeepers who determine, advise and monitor the safe administration of local anesthetic for airway topicalization. What evidence exists to inform our advice?
The study reviewed today is a survey of airway topicalization practices. One of the universal problems with survey studies is a low response rate. While we suspect this survey is no different, the authors met their goal of ideally getting 1,000 responses. The authors do report that 84% of their respondents were consultant anesthetists or equivalent, they do not provide or approximate a denominator for the number of recipients of the survey request, so cannot comment on response rate. Although the results of this survey really don’t provide us with definitive guidance, they do provide a snapshot of what is happening in “real life” practice and suggest a roadmap for future studies. Myron Yaster MD, Melissa Brooks Peterson MD
Original article
Iliff HA, Baxter A, Chakladar A, Endlich Y, McGuire B, Peyton J. Airway topicalization in pediatric anesthesia: An international cross-sectional study. Paediatr Anaesth. 2024 Feb;34(2):145-152. doi: 10.1111/pan.14783. Epub 2023 Oct 11. PMID: 37818989.
Airway topicalization with lidocaine is commonly used in pediatric anesthesia prior to tracheal intubation and by ENT surgeons and pulmonologists prior to laryngoscopy and bronchoscopy. The recommended amount of lidocaine varies widely, ranging from 1-10 mg/kg. Although local anesthetic toxicity (LAST) is theoretically possible because of the rapid absorption of lidocaine from the trachea and lungs, it has rarely been reported when used intraoperatively.1 “The primary aim of today’s study was to ascertain current international dosing practices (mg.kg−1and concentration of solution) for lidocaine airway topicalization in children. The secondary aims included examining aftercare instructions for those receiving lidocaine airway topicalization and instances of LAST secondary to the use of lidocaine for airway topicalization in pediatric patients.”2
“After initial exclusions, 1501 participants from 69 countries across six continents were included" in this survey study. 1262/1501 (84.1%) responses were from “consultant anesthetists or those with an equivalent level of experience. The maximum dose reported by participants who use lidocaine for airway topicalization as part of their normal practice was 5 mg.kg−1 (4–6 mg.kg−1 [0.5–50]) median (interquartile range [range]) over 2 h (1-4 h [0– 30]).”2 It is critical for us to point out the upper limit of the range of maximum dose – a whopping 50 mg/kg. No typo there – 50 mg/kg is insanely high, and we hope this dose resulted in some sort of case review at that institution. That being said, a median of 5 mg/kg does seem reasonable and serves as a good “baseline” for future study design.
The maximum dose of lidocaine for topicalization remains unknown. As it is usually based on body weight, the authors point out that with the increasing incidence of childhood obesity, future studies need to look at what body weight metric should be used: real? ideal? Should a maximum dose be used regardless of body weight? Finally, the most commonly used concentration in this survey study is 4% (40 mg/mL). We agree with the authors’ interpretation of this concentration as probably reflecting medication availability and manufacturing, and not any choice or home-made preparation of local anesthetic. In our clinical practice, there is some variability in “who uses which concentration” – with pediatric anesthesiologists administering 4% and pulmonologists tending to administer lower concentration (1% most commonly). Practice differences were not evaluated in this study, but could be included in future investigations.
A secondary outcome was to identify any incidences of toxicity (LAST). The survey asked for any incidents of toxicity and if there had been, for the clinical details. “Ten participants reported a single incident of local anesthetic systemic toxicity secondary to airway topicalization with lidocaine in which they were personally involved. Two could not provide any additional details.” The remaining eight occurred across five continents, with two children who had seizures receiving doses of 6 and 5 mg.kg-1 over 1 hour. Three other children had doses of 7 and 3 mg.kg-1 over 1 hour and 5 mg.kg-1 over an unknown period of time, two of whom had somnolence and one who had a seizure. Other signs/symptoms included twitches, tachyarrhythmia or perioral tingling. We think that the occurrence of LAST is likely an underestimation in this pediatric population, given that children may not be able to report less severe symptoms of LAST and most children will be anesthetized under general anesthesia. We hope that ongoing efforts at capturing intra- and peri-operative complications in electronic medical records systems will encourage reporting of complications from anesthesia, and give our field an opportunity to examine best practices for complications (which are thankfully rare, but deserve to be studied).
The authors conclude: “The results support the need for further research and consensus in this area, in order to provide safe provision of lidocaine airway topicalization in children. It is hoped the results of this study can support future collaborative work in this area.”2 We wholeheartedly agree with this conclusion, and look forward to seeing future – and more impactful – investigations.
Send your thoughts to Myron who will post in a Friday reader response.
References
1. Eisenberg J, Tedford NJ, Weaver N, Becker S, Moss MJ. Adverse Outcomes in Topical Lidocaine Exposure: A Pediatric Case Series From the United States National Poison Data System. Clinical pediatrics. Nov 2023;62(11):1390-1397. doi:10.1177/00099228231159646
2. Iliff HA, Baxter A, Chakladar A, Endlich Y, McGuire B, Peyton J. Airway topicalization in pediatric anesthesia: An international cross-sectional study. Paediatric anaesthesia. Feb 2024;34(2):145-152. doi:10.1111/pan.14783