Related Experiment Video
Updated: Oct 7, 2025
Optic Nerve Sheath Point of Care Ultrasound: Image Acquisition
Published on: August 18, 2023
Change in the optic nerve sheath diameter after deflation of a pneumatic tourniquet: a prospective observational
Ha-Jung Kim1, Yeon Ju Kim1, Jiyoung Kim1
1Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, South Korea.
Abstract:
Applying a pneumatic tourniquet provides surgeons with a bloodless surgical field. However, application of the tourniquet induces various physiological changes. We evaluated the effect of tourniquet deflation on the intracranial pressure by using ultrasonography to measure the optic nerve sheath diameter (ONSD) in patients undergoing lower limb surgery. The ONSD was measured in 20 patients at five time points: after anesthetic induction (T0) and immediately before (T1), immediately after (T2), 5 min after (T3), and 10 min after tourniquet deflation (T4). Hemodynamic and respiratory variables were recorded. The ONSD showed significant differences at each point (P < 0.001). The ONSDs at T2 and T3 were significantly greater than that at T1 (P = 0.0007 and < 0.0001, respectively). The change in the end-tidal carbon dioxide partial pressure (EtCO2) was similar to the change in the ONSD. The change in the ONSD was significantly correlated with the change in the EtCO2 after tourniquet deflation (r = 0.484, P = 0.030). In conclusion, the ONSD, as an indicator of intracranial pressure, increased after tourniquet deflation in patients undergoing lower limb surgery. This was correlated with an increased EtCO2 and arterial carbon dioxide partial pressure.Trial registration: ClinicalTrials.gov (NCT03782077).
