Early Changes in Optic Nerve Sheath Diameter Associated with Endotracheal Tube Versus Laryngeal Mask Airway in Children Undergoing Elective Surgery Under General Anesthesia: A Prospective Observational Study

Purpose: Ultrasonographic optic nerve sheath diameter (ONSD) has been investigated as a noninvasive sonographic marker associated with intracranial pressure. This study aimed to compare the early change in ONSD after airway placement between children managed with an endotracheal tube (ETT) and those managed with a laryngeal mask airway (LMA). Methods: This single-center prospective, non-randomized observational study included 160 children stratified into age groups of 1–4 and 5–11 years, with 40 patients in each airway subgroup. Bilateral mean ONSD was measured before airway placement (T0), immediately after airway placement and initiation of mechanical ventilation (T1), and after airway removal but before full awakening (T2). The primary outcome was the between-device difference in the change in ONSD from T0 to T1. Repeated measurements were analyzed using a linear mixed-effects model, with Holm adjustment for multiple comparisons. Results: The increase in bilateral mean ONSD from T0 to T1 was 0.269 mm greater in the ETT group than in the LMA group (95% confidence interval [CI], 0.131–0.408; Holm-adjusted p < 0.001). The age-specific ETT–LMA difference in change was 0.293 mm in children aged 1–4 years (95% CI, 0.097–0.488; Holm-adjusted p = 0.0068) and 0.246 mm in those aged 5–11 years (95% CI, 0.050–0.442; Holm-adjusted p = 0.0137). The age group × airway device × time interaction was not significant (Holm-adjusted p = 0.743). In exploratory analyses, peak inspiratory and plateau pressures were higher in the ETT group in both age strata. Conclusions: In the early period after airway placement, ETT use was associated with a greater increase in bilateral mean ONSD than LMA use. Although the association was directionally consistent in both age strata, there was no evidence that the magnitude of the effect differed by age group. Because ONSD is not a direct measurement of intracranial pressure, these findings should not be interpreted as evidence of clinical intracranial hypertension or causality. The airway device was not randomized but was determined by surgical and clinical factors and the attending anesthesiologist’s judgment, and the clinical significance of the 0.269 mm difference is uncertain.