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NCT Number: NCT06979999

The Effects of Positive End-expiratory Pressure (PEEP) on Optic Nerve Sheath Diameter in Laparoscopic Cholecystectomy

This prospective interventional study will evaluate the effects of applying positive end-expiratory pressure (PEEP) at 10 cmH₂O on optic nerve sheath diameter (ONSD) in patients undergoing elective laparoscopic cholecystectomy under general anesthesia. A total of approximately 40 adult patients (ASA physical status I-II) will be included following informed consent.

ONSD will be measured using a high-frequency linear ultrasound probe at three predefined intraoperative time points: (T0) 10 minutes after initiation of mechanical ventilation, (T1) 10 minutes after pneumoperitoneum creation, and (T2) 30 minutes after pneumoperitoneum creation. Dynamic lung compliance, peak airway pressure (Ppeak), end-tidal CO₂ (EtCO₂), heart rate, mean arterial pressure, and SpO₂ will also be recorded.

The aim is to assess whether the application of PEEP influences intracranial pressure indicators, particularly ONSD, during laparoscopic procedures. The study may provide valuable insights into the neurophysiological effects of intra-abdominal pressure and mechanical ventilation strategies in surgical patients.

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Key information

Conditions

Positive End-expiratory Pressure (PEEP) Intracranial Pressure Mechanical Ventilation Optic Nerve Sheath Diameter

Age range

18 year–70 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Niğde Training and Research Hospital

Niğde, Niğde Province, 5200, Turkey (Türkiye)

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Adult patients (age ≥ 18 years)

American Society of Anesthesiologists (ASA) physical status I-III

Scheduled for elective laparoscopic cholecystectomy under general anesthesia

Signed informed consent

Exclusion criteria

  • resence of acute or chronic eye disease

Uncontrolled hypertension

Asthma or known chronic pulmonary disease

Any neurological disorders

Body mass index (BMI) > 35 kg/m²

Use of medications known to affect intracranial pressure

Refusal to participate after signing informed consent

Treatment and study plan

Positive End-Expiratory Pressure (PEEP)

Procedure

Application of 10 cmH₂O PEEP during mechanical ventilation after pneumoperitoneum creation in patients undergoing laparoscopic cholecystectomy.

Primary outcomes

  1. Change in Optic Nerve Sheath Diameter (ONSD)

    Time frame: Intraoperative; T0, T1, T2

    ONSD will be measured via ultrasound at 3 time points during surgery.

Secondary outcomes

  1. Change in Peak Airway Pressure (Ppeak)

    Time frame: Intraoperative measurement at T0, T1, and T2

    Peak airway pressure will be measured using the ventilator settings at three predefined intraoperative time points to evaluate respiratory mechanics during PEEP application.

  2. Change in Dynamic Lung Compliance

    Time frame: Intraoperative measurement at T0, T1, and T2

    Dynamic lung compliance will be calculated using the formula: Tidal Volume / (Ppeak - PEEP) and measured at three intraoperative time points.

  3. Change in End-Tidal Carbon Dioxide (EtCO₂)

    Time frame: Intraoperative measurement at T0, T1, and T2

    End-tidal CO₂ levels will be recorded intraoperatively to monitor changes in ventilation efficiency during surgery.

  4. Changes in Heart Rate (HR) and Mean Arterial Pressure (MAP) Time Frame

    Time frame: Intraoperative measurement at T0, T1, and T2

    Heart rate and mean arterial pressure will be recorded at predefined time points to assess hemodynamic stability during surgery.

  5. Peripheral Oxygen Saturation (SpO₂)

    Time frame: Intraoperative continuous monitoring and recorded at T0, T1, and T2

    Peripheral oxygen saturation will be monitored continuously and recorded at specified intraoperative time points.

Sponsors and collaborators

Lead sponsor

Nigde Omer Halisdemir University

Other

Registry information

Official study title

The Effects of Positive End-Expiratory Pressure (PEEP) on Optic Nerve Sheath Diameter (ONSD) in Patients Undergoing Laparoscopic Cholecystectomy Under General Anesthesia: A Prospective Interventional Study

Acronym: PEEPON

Important dates

Study start
2024
Primary completion
2025
Study completion
2025
First posted
May 20, 2025
Registry last updated
Jun 2, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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