Background/aim: The aim of this study was to evaluate changes in intracranial pressure following tourniquet deflation using noninvasive ultrasonographic optic nerve sheath diameter (ONSD) measurements. Materials and methods: Our study included 59 adult patients between the ages of 18 and 65 years from the American Society of Anesthesiologists (ASA) I/II risk groups who were scheduled to undergo elective orthopedic surgery of the lower extremities using a tourniquet under general anesthesia. ONSD and end-tidal CO2 (ETCO2) were measured 5 times: 15 min prior to the anesthesia induction; just prior to the deflation of the tourniquet; and at 5, 10, and 15 min after the deflation. Additionally, age, sex, weight, height, ASA score, and duration of operation and tourniquet usage were recorded. Results: The ONSD value measured 5 min after the deflation was significantly higher than all of the remaining measurements. There was a significant correlation between the ONSD and ETCO2 measurements at 5 and 10 min after deflation (r = 0.61, 95% CI 0.42-0.75, P < 0.0001 and r = 0.30, 95% CI 0.04-0.51, P < 0.05, respectively). Conclusion: The ultrasonographic ONSD measurements, which were obtained using a simple and noninvasive approach, increased significantly following tourniquet deflation, and this increase was correlated with an increase in ETCO2.
Keywords: Tourniquet; intracranial pressure; optic nerve sheath diameter.