Cerebral Hemodynamic Effects of Individualized PEEP During Robotic Prostatectomy

August 23, 2026 updated by: Ezgi Budak Ozyalcın, Istanbul University

Comparison of the Effects of Individualized PEEP Titration Versus Standard PEEP on Transcranial Doppler-Measured Cerebral Hemodynamic Parameters and Postoperative Neurocognitive Functions in Patients Undergoing Robotic Prostatectomy in the Trendelenburg Position

This randomized clinical trial will compare two approaches to setting positive end-expiratory pressure (PEEP) during robot-assisted radical prostatectomy performed in the Trendelenburg position. The study aims to determine whether individualized PEEP, selected according to the lowest driving pressure, affects cerebral blood flow and brain oxygenation differently from standard PEEP.

Approximately 45 adult patients undergoing robot-assisted radical prostatectomy will be randomly assigned to receive either individualized PEEP or standard PEEP during general anesthesia. Cerebral blood flow will be assessed noninvasively using transcranial Doppler ultrasound, and brain oxygenation will be monitored using near-infrared spectroscopy. Participants will also undergo brief assessments of attention, cognitive function, delirium, and sedation before and after surgery, with follow-up continuing for up to 48 hours after the operation.

Both ventilation approaches are routinely used in clinical practice, and no experimental drug, device, or additional invasive procedure will be used as part of the study.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

This single-center, prospective, randomized, parallel-group clinical trial will evaluate the effects of individualized positive end-expiratory pressure (PEEP) titration compared with standard fixed PEEP on cerebral hemodynamics during robot-assisted laparoscopic radical prostatectomy performed in steep Trendelenburg position with pneumoperitoneum.

Approximately 45 adult patients aged 18-80 years with American Society of Anesthesiologists (ASA) physical status I-III who are scheduled for robot-assisted laparoscopic radical prostatectomy will be randomized in a 1:1 ratio to either an individualized PEEP group or a standard PEEP group. All patients will receive standardized general anesthesia and volume-controlled ventilation. Ventilation will initially be set with a tidal volume of 8 mL/kg predicted body weight, an inspiratory-to-expiratory ratio of 1:2, and an inspired oxygen fraction of 0.40, with end-tidal carbon dioxide maintained at 35-40 mmHg.

In the standard PEEP group, PEEP will be maintained at 6 cmH2O following a recruitment maneuver. In the individualized PEEP group, a decremental PEEP titration will be performed after recruitment. PEEP will be decreased from 15 to 5 cmH2O in 1-cmH2O steps, and respiratory mechanics will be assessed after 12 respiratory cycles at each level. The PEEP level associated with the lowest driving pressure will be selected as the individualized PEEP and maintained during the relevant intraoperative period.

Cerebral hemodynamics will be assessed using transcranial Doppler ultrasonography of the middle cerebral artery. Pulsatility index and resistance index will be recorded, and noninvasive estimated intracranial pressure will be calculated from the pulsatility index using the formula nICPPI = 10.93 × PI - 1.28. Transcranial Doppler measurements will be performed after anesthesia induction, 60 minutes after initiation of steep Trendelenburg position and pneumoperitoneum, and 10 minutes after termination of Trendelenburg position and pneumoperitoneum before emergence from anesthesia.

The primary outcome will be the between-group difference in the change in noninvasive estimated intracranial pressure from the post-induction measurement to the measurement obtained 60 minutes after initiation of Trendelenburg position and pneumoperitoneum (ΔnICPPI, T4-T2). Secondary assessments will include cerebral oxygenation measured using near-infrared spectroscopy, additional transcranial Doppler parameters, intraoperative hemodynamic and respiratory variables, and postoperative neurocognitive outcomes.

Postoperative attention and cognitive status will be assessed using the Months of the Year Backwards Test, delirium using the Nursing Delirium Screening Scale, and sedation/agitation using the Richmond Agitation-Sedation Scale. These assessments will be performed at predefined postoperative time points for up to 48 hours. Additional postoperative cognitive and delirium assessments will include the Mini-Mental State Examination and 3D-Confusion Assessment Method. The transcranial Doppler operator and postoperative outcome assessors will be blinded to group allocation, while the anesthesiologist performing the PEEP intervention cannot be blinded.

Study Type

Interventional

Enrollment (Estimated)

45

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Turkey (Türkiye)
      • Istanbul, Turkey (Türkiye), 34077
        • Istanbul University-Cerrahpasa, Cerrahpasa Faculty of Medicine
        • Contact:
        • Sub-Investigator:
          • Onur Kökçü
        • Principal Investigator:
          • Ezgi Budak Özyalçın

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Age 18 to 80 years American Society of Anesthesiologists (ASA) physical status I-III Scheduled for robot-assisted laparoscopic radical prostatectomy Provision of written informed consent

Exclusion Criteria:

  • Body mass index (BMI) >35 kg/m² History of surgery requiring at least 1 hour of mechanical ventilation within the previous 2 weeks Severe pulmonary disease New York Heart Association (NYHA) class III-IV heart failure Progressive neuromuscular disease Known cerebrovascular malformation Head or neck anatomical conditions preventing adequate transcranial Doppler ultrasonography Refusal to participate in the study Intraoperative conversion to open surgery

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Triple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Individualized PEEP Group
Patients assigned to this group will undergo a recruitment maneuver followed by decremental PEEP titration from 15 to 5 cmH2O in 1-cmH2O steps. After 12 respiratory cycles at each PEEP level, the PEEP associated with the lowest driving pressure will be selected and maintained.
Other: Individualized PEEP Titration
Following a recruitment maneuver, PEEP will be decreased from 15 to 5 cmH2O in 1-cmH2O steps. Respiratory mechanics will be assessed after 12 respiratory cycles at each step, and the PEEP level producing the lowest driving pressure will be selected as the individualized PEEP and maintained.
Other Names:
  • Driving Pressure-Guided PEEP
Active Comparator: Standard PEEP Group
Patients assigned to this group will undergo a recruitment maneuver followed by standard fixed PEEP of 6 cmH2O during mechanical ventilation.
Other: Standard PEEP Group
Following a recruitment maneuver, PEEP will be maintained at a fixed level of 6 cmH2O during mechanical ventilation.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in Noninvasive Estimated Intracranial Pressure
Time Frame: After anesthesia induction and 60 minutes after initiation of steep Trendelenburg position and pneumoperitoneum
Noninvasive estimated intracranial pressure (nICPPI), expressed in mmHg, will be calculated from the middle cerebral artery pulsatility index (PI) measured by transcranial Doppler ultrasonography using the formula nICPPI = 10.93 × PI - 1.28. The outcome is the change in nICPPI from after anesthesia induction to 60 minutes after initiation of steep Trendelenburg position and pneumoperitoneum, calculated as the later value minus the post-induction value.
After anesthesia induction and 60 minutes after initiation of steep Trendelenburg position and pneumoperitoneum

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Middle Cerebral Artery Pulsatility Index
Time Frame: After anesthesia induction; 60 minutes after initiation of steep Trendelenburg position and pneumoperitoneum; and 10 minutes after termination of Trendelenburg position and pneumoperitoneum, before emergence from anesthesia
Middle cerebral artery pulsatility index (PI) will be measured using transcranial Doppler ultrasonography. PI is a dimensionless index derived from the cerebral arterial blood flow velocity waveform. PI values will be recorded at each predefined assessment time point.
After anesthesia induction; 60 minutes after initiation of steep Trendelenburg position and pneumoperitoneum; and 10 minutes after termination of Trendelenburg position and pneumoperitoneum, before emergence from anesthesia
Middle Cerebral Artery Resistance Index
Time Frame: After anesthesia induction; 60 minutes after initiation of steep Trendelenburg position and pneumoperitoneum; and 10 minutes after termination of Trendelenburg position and pneumoperitoneum, before emergence from anesthesia
Middle cerebral artery resistance index (RI) will be measured using transcranial Doppler ultrasonography. RI is a dimensionless index derived from the cerebral arterial blood flow velocity waveform. RI values will be recorded at each predefined assessment time point.
After anesthesia induction; 60 minutes after initiation of steep Trendelenburg position and pneumoperitoneum; and 10 minutes after termination of Trendelenburg position and pneumoperitoneum, before emergence from anesthesia
Regional Cerebral Oxygen Saturation Measured by Near-Infrared Spectroscopy
Time Frame: Before anesthesia induction; after anesthesia induction; 30 and 60 minutes after initiation of steep Trendelenburg position and pneumoperitoneum; immediately before termination of Trendelenburg position; and 10 minutes after termination, before emergence
Regional cerebral oxygen saturation (rSO2) will be measured using bilateral frontal near-infrared spectroscopy (NIRS) and expressed as a percentage (%). Left and right frontal rSO2 values will be recorded separately at each predefined intraoperative assessment time point.
Before anesthesia induction; after anesthesia induction; 30 and 60 minutes after initiation of steep Trendelenburg position and pneumoperitoneum; immediately before termination of Trendelenburg position; and 10 minutes after termination, before emergence
Months Backward Test Performance Score
Time Frame: Preoperatively and at 12, 24, 36, and 48 hours after surgery
Attention and cognitive performance will be assessed using the Months Backward Test (MBT), in which participants are asked to recite the months of the year in reverse order. Performance will be rated using the detailed 0-to-10-point grading system described by Meagher et al. Higher scores indicate better test performance, based on the participant's ability to understand and engage with the task, sustain and shift attention, complete the reverse sequence, recognize or correct errors, complete the test without errors, and complete the task within the specified time.
Preoperatively and at 12, 24, 36, and 48 hours after surgery
Nursing Delirium Screening Scale Total Score
Time Frame: In the post-anesthesia care unit or intensive care unit, and at 12, 24, 36, and 48 hours after surgery
Postoperative delirium symptoms will be assessed using the Nursing Delirium Screening Scale (NuDESC). The NuDESC total score ranges from 0 to 10 points, with higher scores indicating greater delirium symptom severity. The outcome will be reported as the NuDESC total score in points at each assessment.
In the post-anesthesia care unit or intensive care unit, and at 12, 24, 36, and 48 hours after surgery
Richmond Agitation-Sedation Scale Score
Time Frame: In the post-anesthesia care unit or intensive care unit, and at 12, 24, 36, and 48 hours after surgery
Sedation and agitation will be assessed using the Richmond Agitation-Sedation Scale (RASS). The RASS score ranges from -5 (unarousable) to +4 (combative), with 0 indicating an alert and calm state. The outcome will be reported as the RASS score in points at each assessment.
In the post-anesthesia care unit or intensive care unit, and at 12, 24, 36, and 48 hours after surgery

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Istanbul University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

August 19, 2026

Primary Completion (Estimated)

November 19, 2026

Study Completion (Estimated)

November 30, 2026

Study Registration Dates

First Submitted

August 18, 2026

First Submitted That Met QC Criteria

August 23, 2026

First Posted (Actual)

August 25, 2026

Study Record Updates

Last Update Posted (Actual)

August 25, 2026

Last Update Submitted That Met QC Criteria

August 23, 2026

Last Verified

August 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • E-24687260-604.01-1662792

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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