Key result
Tourniquet deflation is linked to increased ONSD at five minutes, correlating strongly with elevated ETCO2.
Why the study?
Changes in intracranial pressure following tourniquet deflation during lower extremity surgery were not well characterized using noninvasive ultrasonographic optic nerve sheath diameter measurements.
Does tourniquet deflation during lower extremity surgery affect optic nerve sheath diameter and end-tidal CO2?
Observational (n=59)
Does tourniquet deflation during lower extremity surgery affect optic nerve sheath diameter and end-tidal CO2?
Effect estimate: r = 0.61 (95% CI 0.42-0.75)
p-value: p=<0.0001
Tourniquet deflation during lower extremity surgery causes a transient increase in optic nerve sheath diameter, which correlates with an increase in end-tidal CO2.
ONSD rise after tourniquet deflation signals possible transient ICP increase; leaves open clinical relevance and need for outcome studies.
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.
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Beşi̇r et al. (2018) conducted an observational in Elective orthopedic surgery of the lower extremities (n=59). Tourniquet deflation vs. Pre-deflation measurements was evaluated on Correlation between ONSD and ETCO2 measurements at 5 min after deflation (r = 0.61, 95% CI 0.42-0.75, p=<0.0001). Tourniquet deflation significantly increased optic nerve sheath diameter at 5 minutes, correlating with increased end-tidal CO2 (r=0.61; 95% CI 0.42-0.75; P<0.0001).
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