Purpose: The purpose of this study was to assess the extent of the increased intracranial pressure (ICP) resulting from CO₂ pneumoperitoneum and steep Trendelenburg positioning using ultrasonographic measurement of optic nerve sheath diameter (ONSD) in patients undergoing robot-assisted laparoscopic radical prostatectomy (RALRP). Patients and Methods: Twenty patients who underwent elective RALRP were enrolled in this study. ONSD and regional cerebral oxygen saturation (rSO₂) were investigated noninvasively using ocular ultrasonography and near-infrared spectroscopy before anesthesia (T0), 10 minutes after anesthesia induction in the supine position (T1), 10 and 30 minutes after CO₂ pneumoperitoneum with 30-degree Trendelenburg positioning (T2 and T3), and after returning to supine position without CO₂ pneumoperitoneum at the conclusion of the RALRP (T4). Results: The mean values of ONSD at all time points (T1, T2, T3, and T4) after general anesthesia significantly increased compared with that before general anesthesia (T0). During CO₂ pneumoperitoneum with 30-degree Trendelenburg positioning (T2, T3), a significant increase of 12.5% in ONSD was observed in comparison with ONSD after anesthesia induction in the supine position without CO₂ pneumoperitoneum (T1). Three patients had an ONSD value equivalent to an ICP above 20 mm Hg, and these patients did not experience a decrease of rSO₂ or any neurologic complications. Conclusions: In patients undergoing RALRP, the increase of 12.5% in ONSD during CO₂ pneumoperitoneum with steep Trendelenburg positioning was observed and thus the increase of ICP corresponding to this change of ONSD could be predicted. In 15% of the enrolled patients, ONSD increased by values equivalent to an ICP above 20 mm Hg without a deterioration of rSO₂ or any neurologic complications.

Background: Total laparoscopic hysterectomy (TLH) has become a widely accepted alternative to total abdominal hysterectomy (TAH). The aim of this study was to compare the incidence and grade of venous air embolism (VAE) in TLH to those in TAH using transesophageal echocardiography. Methods: Eighty-two American Society of Anesthesiologists physical status I patients scheduled for either TLH or TAH were enrolled. After induction of general anesthesia, a multiplane transesophageal echocardiography probe was inserted. The midesophageal four-chamber or bicaval view was continuously monitored. An independent transesophageal echocardiography-certified anesthesiologist graded VAE. Results: All patients undergoing TLH showed VAE, and 37.5% of patients had VAE grade higher than III. Fifteen percent of patients undergoing TAH showed VAE, and all of them were grade I. No patient in this study showed hemodynamic instability or electrocardiogram changes at the time of VAE occurrence. Most instances of VAE during TLH occurred during transection of the round ligament and dissection of the broad ligament. Conclusion: The incidence of VAE in patients undergoing TLH was 100%. VAE grade in TLH was higher compared to that in TAH, especially during transection of the round ligament and dissection of the broad ligament. Although the hemodynamic instability associated with VAE during TLH was not observed in this study, anesthesiologists must be vigilant for detection of VAE during TLH.