Complete sevoflurane anesthetic for myringotomy tubes is associated with an increased rate of emergence delirium

The current anesthetic standard for bilateral myringotomy tube (BMT) placement in children is induction and maintenance with sevoflurane delivered via mask inhalation. Due to the quick nature of this procedure, the use of an intravenous line (IV) for the delivery of adjuncts has generally been deemed unnecessary. BMT with mask sevoflurane has been commonly associated with a high rate of emergence delirium (ED) as is evidenced by the number of studies offering suggestions to mitigate ED[1] and work highlighting the complications of tympanostomy.[2] The exact cause of this affect is still unclear but recent research points towards patient risk factors, fast onset and offset, and even direct central nervous system stimulating or neurotoxic effects of sevoflurane.[3] Surprisingly, the literature is lacking formal demonstration that patients receiving BMT with sevoflurane have a higher rate of ED than other procedures nor have there been attempts to quantify this difference. We conducted a retrospective cohort study looking at children below 5 years old who underwent either BMT placement or a similarly stimulating short procedure, namely, gastrointestinal endoscopy or laser for dermatologic lesions (non-BMT). This study's protocol was approved by the institutional review board of Oregon Health and Science University (approval No. STUDY00021224; April 7, 2020). Previously validated scales including the modified Yale preoperative anxiety score and Pediatric Emergence Delirium Scale (PAED) were collected from patient charts. Severe delirium was defined as a PAED score of greater than or equal to 10. The time to place an IV measured by the difference between anesthesia start and surgery start between the two groups was also collected. All children in the study received a mask induction with sevoflurane while the BMT patients also received mask sevoflurane maintenance for the entirety of their procedure. Non-intravenous adjunct medications including but not limited to, pre-operative midazolam, intramuscular ketorolac, intranasal dexmedetomidine or intranasal fentanyl were used in the BMT patients at the discretion of the anesthesiologist. All non-BMT patients had an IV placed and received IV medication either as maintenance or adjuvants. These included propofol, alfentanil, fentanyl, dexamethasone and ondansetron and were at the discretion of the anesthesiologist. Data were analyzed using Mann-Whitney U test, Student's t-test, or chi-square test where appropriate (STATA Corp., College Station, TX, USA). This was originally part of a larger quality project to reduce the stress of BMT patients upon an overburdened recovery staff but Institutional Review Board of Oregon Health & Science University, approval was obtained later. Data on 141 (92 BMT and 49 non-BMT) patients were collected from October 2018 through June 2019. The average age of the BMT group was younger than the non-BMT group (2.1 vs. 3.1 years, P < 0.001). The PAED scores were significantly higher in the BMT group that received both induction and maintenance with sevoflurane (7.87 vs. 5.20, P = 0.008). Notably, the percentage of patients with severe PAED was also higher in the BMT group with complete sevoflurane anesthetic (40% vs. 18%, P = 0.02). The modified Yale preoperative anxiety score was significantly higher in the non-BMT group (6.64 vs. 5.25, P = 0.03). The mean time to place the IV in the non-BMT group was 6 minutes. Here we further strengthen the association that has long been suspected; patients undergoing myringotomy tube placement with complete sevoflurane general anesthesia suffer a higher degree of ED and double the rate of severe delirium compared to patients receiving similar procedures with adjunct IV medications. This was despite the non-BMT group having higher anxiety levels preoperatively, a known risk factor for ED4 and all of the non-BMT receiving a sevoflurane induction. This builds on the work of Chandler et al.[5], where they found that total intravenous anesthetic was superior to a sevoflurane induction for strabismus surgery. We found that the use of IV medications was associated with a lower incidence of ED even with a sevoflurane induction. Interestingly, non-IV adjuncts appeared to have little overall effect to mitigate ED in the BMT group, strengthening the association of ED with the use of sevoflurane for induction and maintenance anesthetic. BMT placement is one of the most common surgical procedures in children and burden of ED on patients, caregivers, and hospital staff is enormous. These findings suggest that having the option to give medications intravenously could reduce the incidence of ED. Limitations include small sample size from a single institution and a small, but arguably clinically insignificant, age difference between the two groups. Comparison between these two categories of procedures highlights the difficulty in finding similar procedures in similar patient groups. Nonetheless, here we demonstrate a higher rate of ED among BMT patients receiving complete sevoflurane anesthesia and a starkly higher rate of severe ED. Identifying and quantifying ED in this population is a large step in improving the quality of care for these patients and highlights the need for further investigation into how inhaled anesthetics affect perioperative care in pediatric patients.