Impact of mannitol on intracranial pressure assessed by optic nerve sheath ultrasonography during video-laparoscopic prostatectomy: a randomized clinical trial

TL;DR

This study found that giving mannitol during prostate surgery did not significantly affect intracranial pressure, as measured by optic nerve sheath diameter.

Contribution

The study is the first to evaluate mannitol's intraoperative effects on intracranial pressure during video-laparoscopic prostatectomy using optic nerve sheath ultrasonography.

Findings

ONSD increased in both groups during surgery but decreased similarly at the final measurement.

Mannitol did not significantly alter ONSD trajectory or extubation time compared to the control group.

The dose and timing of mannitol used were ineffective in modifying intraoperative intracranial pressure measures.

Abstract

Intracranial pressure can increase during video-laparoscopic prostatectomy due to the Trendelenburg position and pneumoperitoneum, potentially leading to complications. The Optic Nerve Sheath Diameter (ONSD) has emerged as a reliable, non-invasive method to assess ICP. Mannitol is commonly used to reduce ICP, but its intraoperative effects in this surgical setting remain unclear. This study aimed to evaluate the impact of mannitol administration on ICP, as assessed by ONSD.

This single-center, randomized, parallel-group, non-blinded clinical trial, 1:1 allocation, included 48 patients undergoing video-laparoscopic prostatectomy at a tertiary hospital in Brazil. Participants were randomly assigned to either the Mannitol Group, receiving 0.5 g.kg-1 of intravenous mannitol after 120 minutes in Trendelenburg, or the Control Group, which did not receive mannitol. ONSD was measured using ultrasonography at four intraoperative time points (T1–T4). Additional variables analyzed included hemodynamic and respiratory parameters, surgery duration, and extubation time. Statistical analysis was conducted using a linear mixed-effects model.

ONSD increased in both groups between T1 and T3, followed by a reduction at T4. However, the decrease in ONSD in the Mannitol Group was not statistically significant compared to the Control Group. Regarding extubation, the mean extubation time was 24.04 ± 15.71 minutes in the Mannitol Group and 22.79 ± 15.37 minutes in the Control Group (p = 0.782).

Mannitol administration during video-laparoscopic prostatectomy did not result in significant differences in ONSD trajectory or extubation time compared with the control group. At the dose and timing used, mannitol did not modify intraoperative surrogate measures of intracranial pressure.

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