Abstract
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.
Highlights
Pneumatic tourniquets have frequently been used in orthopedic surgeries in order to provide a bloodless surgical area and reduce blood loss via wrapping around the extremities
heart rate (HR), Heart rate; mean blood pressure (MAP), mean arterial pressure; BIS, bispectral index; ONSD, optic nerve sheath diameter. a: Significant reduction compared to T0 (P < 0.05) and Ti (P < 0.05). b: Significant increase compared to Td5 (P < 0.05). c: Significant increase compared to T0 (P < 0.05) and Ti (P < 0.05). d: Significant increase compared to T0 (P < 0.05). e: Significant increase compared to other periods (P < 0.05)
Following the application of the inclusion and exclusion criteria, only 59 adult patients aged between 18 and 65 years who were American Society of Anesthesiologists (ASA) I–II and were scheduled to undergo elective orthopedic surgery of the lower extremities using a tourniquet were included for study analysis between April 2016 and January 2017
Summary
Pneumatic tourniquets have frequently been used in orthopedic surgeries in order to provide a bloodless surgical area and reduce blood loss via wrapping around the extremities. When the tourniquet is inflated, metabolic changes such as increases in carbon dioxide (CO2), lactic acid, and potassium and reductions in PaO2 and pH are observed in the ischemic extremity These ischemic products are secreted into the general circulation following deflation of the tourniquet [2]. The sudden increase in ETCO2 observed after the deflation is associated with a 50% increase in the middle cerebral artery blood flow velocity, which peaks at approximately 2–4 min and regresses to normal values after 8–10 min [4]. This transient increase is well tolerated in ICP is monitored in many clinical studies using both invasive and noninvasive methods. The aim of our investigation was to define the change in ONSD and the correlation between this change and ETCO2 after tourniquet deflation
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