Anestesia e Investigación Clínica
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abstracto

Optic Nerve Sheath Diameter Changes with Changing Intra-abdominal Pressure and End-Tidal CO2 in Laparoscopic Surgery: A Prospective, Observational Study

Anjali Kumari*

Introduction: Measurement of ONSD by ultrasonography is a surrogate measure of ICP in laparoscopic surgeries. This study aimed to evaluate the change in ONSD with changes in IAP and EtCO₂ in patients undergoing laparoscopic cholecystectomy.

Methods: After approval from IEC and BOS, 60 adult patients undergoing elective surgery were selected for the study. Optic nerve aligned directly opposite the 6 MHz-13 MHz linear probe of USG machine of Hitachi Aloka F31 and ONSD measured 3 mm behind the globe perpendicular to axis of the scanning plane at T0, T1, T2, T3 i.e. after intubation, at IAP of 10 mm Hg, 15 mm Hg and after desufflation. Further, the changes in ONSD corresponding to changes in IAP were measured after standardizing EtCO₂ to normal level (35 mm Hg-40 mm Hg).

Result: There was significant variation in ONSD (p<0.001) with reference to IAP. EtCO₂ went beyond 40 mm Hg in 30% of cases and the increase in ONSD was significantly more (p<0.001) as compared to the patients in whom EtCO₂ was within the normal range.

Conclusion: ONSD is a non-invasive, easily performed approach and varies significantly with IAP. Therefore we can imply that increase in IAP can indirectly lead to increase in ICP in clinical scenarios of acute elevations of IAP. A rise in EtCO₂>40 mm Hg can also be used as an individual evidence of a rise in ICP in cases where ONSD cannot be measured.