Evaluation of Cerebral Perfusion in Supine and Steep Trendelenburg Positions During Robotic Prostatectomy

Evaluation of Cerebral Perfusion in Supine and Steep Trendelenburg Positions During Robotic Prostatectomy Robotic endoscopic radical prostatectomy requires pneumoperitoneum and the steep Trendelenburg position to ensure optimal surgical visualization. However, this combination may increase intracranial pressure (ICP) and alter cerebral blood flow and oxygenation.

This study aimed to evaluate cerebral perfusion changes in patients undergoing robotic prostatectomy by using Transcranial Doppler (TCD) and Near-Infrared Spectroscopy (NIRS). Cerebral blood flow velocity in the middle cerebral artery and pulsatility index (PI) were measured to estimate ICP, while NIRS was used to assess cerebral oxygen saturation.

Additionally, arterial blood gas parameters (PCO₂, PO₂, Hb), end-tidal CO₂, and mean arterial pressure (MAP) were recorded. Pre- and postoperative Mini-Mental State Examination (MMSE) scores were compared to evaluate potential cognitive effects.

The aim was to determine the relationship between ICP estimation, cerebral oxygenation, and hemodynamic variables during supine and steep Trendelenburg positions in robotic prostatectomy.

Study Overview

• Status: Not yet recruiting
• Conditions: Cerebral Perfusion Pressure; Trendelenburg

Detailed Description

The use of robotic endoscopic radical prostatectomy has the potential to improve surgical outcomes and reduce complications compared to open radical prostatectomy. Robotic endoscopic abdominal surgery involves carbon dioxide (CO₂) insufflation to create pneumoperitoneum and requires the Trendelenburg position to provide adequate surgical visualization.

An increase in intra-abdominal pressure due to pneumoperitoneum leads to various physiological changes. The combination of steep Trendelenburg positioning and pneumoperitoneum during robotic prostatectomy is known to cause intracranial hypertension. The elevation of intra-abdominal pressure and Trendelenburg positioning increases intracranial pressure (ICP) and alters cerebral blood flow (CBF). These changes in cerebral hemodynamics may have detrimental effects on cerebral oxygenation.

Several invasive and non-invasive techniques are available for monitoring ICP and cerebral perfusion pressure (CPP). Among non-invasive methods, Transcranial Doppler ultrasonography (TCD) and Near-Infrared Spectroscopy (NIRS) are reliable and safe monitoring tools.

TCD measures blood flow velocities in the major arteries of the Circle of Willis. Based on TCD-derived data, several formulas have been proposed to estimate ICP, such as the Pulsatility Index (PI) and Resistance Index (RI).

PI is calculated using the formula:

PI = (Peak systolic velocity - End diastolic velocity) / Mean velocity. A normal PI typically ranges between 0.5 and 1.2. Under normal systemic hemodynamic conditions, an elevated PI (particularly >2) suggests reduced cerebral perfusion pressure (CPP).

RI is calculated as:

RI = (Peak systolic velocity - End diastolic velocity) / Peak systolic velocity.

An RI greater than 0.75-0.8 is considered abnormal. RI is conceptually similar to PI (both increase in cases of low CPP), although PI is more widely used in clinical practice.

Normal ICP values vary with age and body position, but are generally 5-15 mmHg in healthy supine adults, 3-7 mmHg in children, and 1.5-6 mmHg in infants.

In cases of elevated ICP or circulatory hypotension, cerebral perfusion pressure (CPP) decreases. CPP is calculated as the difference between mean arterial pressure (MAP) and ICP. MAP is obtained by adding one-third of the pulse pressure (the difference between systolic and diastolic pressure) to the diastolic pressure.

NIRS technology was recently developed to enable continuous and non-invasive monitoring of regional cerebral tissue oxygen saturation for various clinical indications. The differing absorption spectra of oxygenated and deoxygenated hemoglobin at different light wavelengths allow for assessment of the balance between cerebral oxygen supply and demand.

In this study, the correlation between cerebral oxygen saturation measured by NIRS and estimated ICP calculated from TCD-derived middle cerebral artery (MCA) flow velocity and pulsatility index was evaluated. In addition, arterial blood gas parameters (PCO₂, PO₂, hemoglobin), end-tidal CO₂ (EtCO₂), and mean arterial pressure (MAP) were included in the analysis.

Preoperative and postoperative Mini-Mental State Examination (MMSE) tests were administered to assess potential cognitive changes and to compare our non-invasive monitoring results with clinical outcomes.

• Study Type: Observational
• Enrollment (Estimated): 60

Contacts and Locations

• Study Contact: Name: Hanife Kabukcu; Phone Number: +905337319555; Email: hanifekabukcu@akdeniz.edu.tr
• Study Contact Backup: Name: Sinem Omca; Phone Number: +905061187398; Email: snmomca@gmail.com

Study Locations

• Turkey (Türkiye)
  • Antalya
    • Antalya, Antalya, Turkey (Türkiye)
      • Akdeniz University
      • Contact: Hanife Kabukcu; Phone Number: +905337319555; Email: hanifekabukcu@akdeniz.edu.tr
      • Contact: Sinem Omca; Phone Number: +905061187398; Email: snmomca@gmail.com
      • Principal Investigator: Sinem Omca
      • Sub-Investigator: Hanife Kabukcu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Male patients aged 18 to 80 years undergoing robotic prostate surgery under general anesthesia.

Description

Inclusion Criteria:

Male patients aged 18 to 80 years

ASA physical status I-III

Scheduled for robotic prostate surgery under general anesthesia

Able and willing to provide written informed consent

Exclusion Criteria:

Decline or inability to provide informed consent

Age <18 years or >80 years

Inability to perform ultrasonographic measurements or to maintain the required surgical position

Presence of intracranial space-occupying lesions

History of cerebrovascular accident (CVA) or carotid artery occlusion

Known neurological disorders (e.g., epilepsy)

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort
Patients Robotic Prostate Surgery; Men aged 18 to 80 undergoing robotic prostate surgery

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Cerebral Oxygenation Measured by Near-Infrared Spectroscopy (NIRS)	Cerebral oxygenation will be assessed using near-infrared spectroscopy (NIRS). Regional cerebral oxygen saturation (%) will be continuously monitored, and values will be recorded at predefined perioperative time points.	1.Upon arrival in the operating room (baseline) 2.10 minutes after endotracheal intubation 3.30 minutes after placement in the Trendelenburg position 4.10 minutes before returning to the supine position 5. Postoperative 1 hour
Middle Cerebral Artery Blood Flow Velocity Measured by Transcranial Doppler Ultrasonography (TCD)	Middle cerebral artery (MCA) blood flow velocity will be measured using transcranial Doppler ultrasonography (TCD). MCA mean flow velocity (cm/s) will be recorded at predefined perioperative time points.	1.Supine position, 10 minutes after endotracheal intubation 2.30 minutes after placement in the Trendelenburg position 3.10 minutes before returning to the supine position 4.After returning to the supine position 5.Postoperative 1 hour

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mean Arterial Pressure (MAP) at Predefined Perioperative Time Points	Mean arterial pressure (mmHg) will be recorded continuously and extracted at predefined perioperative time points to assess hemodynamic changes associated with patient positioning.	1.Upon arrival in the operating room 2.10 minutes after endotracheal intubation 3.30 minutes after placement in the Trendelenburg position 4.10 minutes before returning to supine 5.Postoperative 1 hour
End-Tidal CO₂ (EtCO₂) at Predefined Perioperative Time Points	End-tidal carbon dioxide (mmHg) will be monitored continuously and documented at several standardized perioperative time points to assess potential effects of Trendelenburg positioning and pneumoperitoneum on ventilation.	1.Upon arrival in the operating room 2.10 minutes after endotracheal intubation 3.30 minutes after placement in the Trendelenburg position 4.10 minutes before returning to supine 5.Postoperative 1 hour

Collaborators and Investigators

• Sponsor: Hanife Kabukcu
• Investigators: Study Director: Hanife Kabukcu, Akdeniz University; Principal Investigator: Sinem Omca, Akdeniz University

Publications and helpful links

General Publications

• Kalmar AF, Foubert L, Hendrickx JF, Mottrie A, Absalom A, Mortier EP, Struys MM. Influence of steep Trendelenburg position and CO(2) pneumoperitoneum on cardiovascular, cerebrovascular, and respiratory homeostasis during robotic prostatectomy. Br J Anaesth. 2010 Apr;104(4):433-9. doi: 10.1093/bja/aeq018. Epub 2010 Feb 18.
• Kalmar AF, Dewaele F, Foubert L, Hendrickx JF, Heeremans EH, Struys MM, Absalom A. Cerebral haemodynamic physiology during steep Trendelenburg position and CO(2) pneumoperitoneum. Br J Anaesth. 2012 Mar;108(3):478-84. doi: 10.1093/bja/aer448. Epub 2012 Jan 17.

Study record dates

Study Major Dates

• Study Start (Estimated): January 1, 2026
• Primary Completion (Estimated): October 30, 2026
• Study Completion (Estimated): November 1, 2026

Study Registration Dates

• First Submitted: November 17, 2025
• First Submitted That Met QC Criteria: December 24, 2025
• First Posted (Actual): January 5, 2026

Study Record Updates

• Last Update Posted (Actual): January 5, 2026
• Last Update Submitted That Met QC Criteria: December 24, 2025
• Last Verified: November 1, 2025

More Information

Terms related to this study

• Keywords: EEG; NIRS; TRANSCRANİAL DOPPLER USG; CEREBRAL PERFUSİON; TRENDELENBURG; PATİENT STATE İNDEKS; ROBOTİC SURGERY; PROSTATEKTOMİ
• Other Study ID Numbers: Cerebral Perfusion in Position

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: IPD used in publishing the results
• IPD Sharing Time Frame: The data will be available from October 5, 2025, to October 30, 2026, and will be shared after the study results have been finalized and published.
• IPD Sharing Access Criteria: finalization of the results
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No