Effect of Percutaneous Tracheostomy on Optic Nerve Sheath Diameter [TONS Trial]

Elective percutaneous tracheostomy [PCT] is the widely performed procedure in neurocritically ill patients as an airway management choice in neurocritical care unit [NICU]. Intracranial pressure [ICP] is a vital parameter to be monitored in these patients while undergoing any surgical procedure including PCT. Optic nerve sheath diameter [ONSD], being a surrogate of ICP, can be done bedside and carries less complications than invasive ICP monitoring. The aim of our study was to assess the effect of PCT on ONSD at different stages of PCT.

A total of 158 patients with various intracranial pathologies scheduled for PCT in NICU were screened for eligibility in our study. We assessed mean values of ONSD, HR, MBP, and SpO₂ for changes over various time points during PCT using generalized estimating equation (GEE). A p value of <0.05 was considered significant.

A total of 135 patients who underwent PCT were analyzed for the study. The values of ONSD changed significantly at different stages of PCT procedure compared to baseline. The baseline ONSD value was 0.39 ± 0.05 cm. ONSD rose significantly to 0.40 ± 0.06 cm during positioning, 0.41 ± 0.06 cm during skin incision, 0.42 ± 0.07 cm during dilatation of tract, 0.41 ± 0.07 cm during insertion of tracheostomy, and 0.41 ± 0.06 cm at the end of the procedure.

PCT leads to a significant rise of ONSD values during all stages of PCT. The available evidences point toward detrimental rise in ICP during PCT. ICP can be monitored noninvasively by measuring ONSD using bedside ultrasound.

Kapoor I, Wanchoo J, Mahajan C, Singhal V, Roy H, Kumar S, et al. Effect of Percutaneous Tracheostomy on Optic Nerve Sheath Diameter [TONS Trial]. Indian J Crit Care Med 2021;25(4):382-387.