Transcutaneous Auricular Vagus Nerve Stimulation for Preventing Emergence Agitation and Delirium After Pediatric Tonsillectomy and Adenoidectomy: A Randomized, Double-Blind, Interventional Study

Background and Rationale Emergence delirium (ED) in pediatric patients is a common postoperative complication linked to exposure to volatile anesthetics, particularly sevoflurane. The proposed mechanism involves dysregulation of the autonomic nervous system, characterized by reduced vagal tone and sympathetic hyperactivity. Transcutaneous auricular vagus nerve stimulation (taVNS) is a non-invasive neuromodulation technique designed to increase vagal activity by delivering low-intensity electrical currents to the auricular branch of the vagus nerve in the ear. Preclinical and clinical evidence suggests taVNS can exert anti-inflammatory, analgesic, and anxiolytic effects via central and peripheral pathways. This trial is designed to investigate whether perioperative taVNS can mitigate ED by modulating autonomic balance.

Intervention and Blinding Methodology The study employs a double-blind, sham-controlled design. Active and sham stimulation devices are physically identical. The active device delivers electrical stimulation with parameters set at a frequency of 25 Hz, a pulse width of 300 μs, and a cyclic mode of 30 seconds on followed by 30 seconds off. Stimulation intensity is individually titrated to a perceptible but non-painful tingling sensation. The sham device follows an identical placement and titration procedure but ceases output after the initial adjustment phase. This methodology ensures participants, caregivers, and outcome assessors are blinded to group assignment. Stimulation is initiated in the preoperative holding area, continues intraoperatively, and concludes upon discharge from the post-anesthesia care unit (PACU). Supplemental stimulation sessions are administered on postoperative days 1 and 2.

Study Procedures Overview Following enrollment and randomization, the stimulation device is applied to the left auricular concha. Standardized general anesthesia is administered per protocol, utilizing sevoflurane for maintenance with titration guided by bispectral index (BIS) monitoring. Intraoperative vital signs and anesthetic depth are recorded. Upon cessation of anesthetics, continuous behavioral observation begins in the PACU.

Technical and Mechanistic Considerations The selection of the left auricle for stimulation is based on anatomical studies indicating a lower density of cardiac vagal fibers compared to the right side. The chosen stimulation parameters (25 Hz, 300 μs) are derived from prior neurophysiology studies suggesting efficacy in activating afferent vagal pathways. The cyclic on/off pattern is intended to prevent nerve accommodation. The perioperative timing of stimulation is designed to preemptively modulate autonomic tone prior to the emergence phase, a period of high neurophysiological lability.

Data Collection and Management Primary and secondary outcome data are collected at predetermined time points by trained, blinded assessors. Data pertaining to device adherence (session timing, wear status) are recorded by nursing staff. All data are entered into a secure, electronic data capture system. Source data verification is performed per the monitoring plan.