The Effect of Positive End-Expiratory Pressure Levels on Perfusion Index and Neurocognitive Functions in Geriatric Patients

Investigation of the Effect of Different Positive End-Expiratory Pressure (PEEP) Levels on Perfusion Index (PI) and Neurocognitive Functions in Geriatric Patients Undergoing Laparoscopic Cholecystectomy Surgery

With the increasing geriatric population, age-related physiological changes and common comorbidities increase the risk of surgical and anesthesia-related complications in this patient group. Therefore, careful planning of anesthesia management and ventilation strategies is crucial to achieve safe and successful clinical outcomes. Positive end-expiratory pressure (PEEP), one of these strategies, should be applied with careful consideration of the balance between ensuring oxygenation and maintaining cardiovascular stability in geriatric patients. Early detection of hypoperfusion during the intraoperative period is also an important part of perioperative management. To this end, near-infrared spectroscopy (NIRS) is used as a noninvasive monitoring method to assess cerebral oxygenation, while the perfusion index (PI) is used to evaluate peripheral circulation, providing clinicians with valuable information for predicting potential complications. However, one of the most important neurological complications that can occur after surgery in geriatric patients is postoperative cognitive dysfunction (POCD). The Mini-Mental State Examination (MMSE) is widely preferred for assessing cognitive function during the perioperative period due to its ease of application and reliability.

The primary objective of this study is to investigate the effects of different PEEP levels on PI in geriatric patients undergoing laparoscopic cholecystectomy and to reveal changes in neurocognitive function by comparing preoperative and postoperative MMSE scores. Our secondary objectives are to evaluate the effects of PEEP on NIRS values and to analyze the possible relationships between NIRS, PI, hemodynamic parameters, and MMSE scores.

Study Overview

• Status: Completed
• Conditions: General Anesthesia; Elective Laparoscopic Cholecystectomy
• Intervention / Treatment: Other: PEEP levels

Detailed Description

This study was conducted at the General Surgery Operating Room of Ankara Bilkent City Hospital, Ministry of Health, Turkey, with a total of 78 patients aged 65 years and older who were scheduled to undergo elective laparoscopic cholecystectomy. The study was designed as a prospective randomized controlled trial. Using a computer-assisted randomization method, the 78 patients were divided into three groups. Group 5 was ventilated with 5 cmH₂O PEEP, Group 7 with 7 cmH₂O PEEP, and Group 9 with 9 cmH₂O PEEP. On the day of surgery, patients' age, gender, height, weight, body mass index (BMI), comorbidities, medications taken regularly, surgical history, and education level were recorded using a standardized data form in the preoperative waiting area. The Mini Mental State Examination (MMSE) was administered to all patients 2 hours before surgery. After patients were taken to the operating room, noninvasive arterial blood pressure, electrocardiography (ECG), and pulse oximetry were performed as part of standard monitoring. Additionally, four-channel frontal EEG-based SedLine® (Patient State Index, PSI; Masimo Corporation, Irvine, CA, USA) monitoring was used to monitor anesthesia depth, and NIRS (O3® regional oximetry, Masimo Corporation, Irvine, CA, USA) monitoring was used to assess cerebral oxygenation. After cleaning the forehead area with an appropriate antiseptic, the SedLine® PSI electrode and O3® NIRS sensors were placed, and baseline values were recorded. For peripheral perfusion monitoring, the PI probe (Masimo Rainbow® Pulse CO-Oximetry, Masimo Corporation, Irvine, CA, USA) was placed on the third finger of the hand without the noninvasive blood pressure cuff. The hand was wrapped to reduce optical interference from ambient light and maintain thermal equilibrium. Before anesthesia induction, 3 minutes of preoxygenation was administered with 100% oxygen via a balloon mask. Anesthesia induction was then performed with fentanyl (2 mcg/kg), lidocaine (1 mg/kg), propofol (2 mg/kg), and rocuronium (0.6 mg/kg); midazolam was not administered. After achieving adequate depth of anesthesia, an endotracheal tube of appropriate size was placed in the patient. Ventilator settings were adjusted to a 50:50 oxygen-air mixture and a fresh gas flow of 2 L/min, targeting a tidal volume of 6-8 mL/kg based on ideal body weight and maintaining EtCO₂ within the range of 35-45 mmHg. PEEP was applied at a level determined by randomization in each patient. Anesthesia maintenance was achieved with sevoflurane and remifentanil infusion (0.01-0.1 mcg/kg/min) to maintain a target PSI range of 25-50. An orogastric tube was placed for gastric decompression. The surgical procedure was performed using the standard laparoscopic cholecystectomy technique. Pneumoperitoneum pressure was adjusted and maintained at 10-12 mmHg; the operating table was positioned at approximately 30° reverse Trendelenburg. Operating room temperature was maintained at 18-20 °C. Parameters evaluated (SAP, DAP, MAP, heart rate, SpO₂, PI, PSI, NIRS left and right) before and after anesthesia induction; after intubation; before pneumoperitoneum and at 1, 5, 10, 15, 30, 45, and 60 minutes after the start of pneumoperitoneum; every 30 minutes thereafter; and also at the end of pneumoperitoneum, at the end of surgery, and after extubation. Additionally, the hemoglobin levels at admission and discharge, the total amount of fluid administered, and the duration of anesthesia and surgery were also recorded. For postoperative pain management, patients received standard tramadol 1 mg/kg IV and paracetamol 1 g IV after gallbladder removal. Following the operation, 2 mg/kg sugammadex IV was administered, and patients were extubated once they began spontaneous breathing. After recovery in the operating room, patients were transferred to the postoperative recovery room. On postoperative day 1, patients underwent the MMSE test, and the results were recorded. Additionally, if any complications developed during the postoperative period, this was noted.

• Study Type: Interventional
• Enrollment (Actual): 78
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Çankaya
    • Ankara, Çankaya, Turkey (Türkiye), 06800
      • Ankara Bilkent City Hospital

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Patients who are 65 years and older
• Patients in the ASA I-III risk group
• Under elective conditions, patients those undergo elective laparoscopic cholecystectomy
• Voluntary patients

Exclusion Criteria:

• Patients under age 65
• Emergency surgical procedures
• Patients with neurological or psychiatric disorders
• Patients with severe restrictive or obstructive lung disease
• Patients with serious cardiac pathology (EF<40 or presence of arrhythmia)
• Patients with peripheral artery disease
• Patients with increased intracranial pressure
• Morbidly obese patients
• Patients do not want to participate in the study

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Screening
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: 5 cmH₂O PEEP Ventilation; Group 5 was ventilated with 5 cmH₂O PEEP.	Other: PEEP levels; 78 patients undergoing elective surgery in the General Surgery Operating Room were divided into three groups using a computer-assisted randomization method. Group 5 was ventilated with 5 cmH₂O PEEP, Group 7 with 7 cmH₂O PEEP, and Group 9 with 9 cmH₂O PEEP.
Active Comparator: 7 cmH₂O PEEP Ventilation; Group 7 was ventilated with 7 cmH₂O PEEP.	Other: PEEP levels; 78 patients undergoing elective surgery in the General Surgery Operating Room were divided into three groups using a computer-assisted randomization method. Group 5 was ventilated with 5 cmH₂O PEEP, Group 7 with 7 cmH₂O PEEP, and Group 9 with 9 cmH₂O PEEP.
Active Comparator: 9 cmH₂O PEEP Ventilation; Group 9 was ventilated with 9 cmH₂O PEEP.	Other: PEEP levels; 78 patients undergoing elective surgery in the General Surgery Operating Room were divided into three groups using a computer-assisted randomization method. Group 5 was ventilated with 5 cmH₂O PEEP, Group 7 with 7 cmH₂O PEEP, and Group 9 with 9 cmH₂O PEEP.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Neurocognitive functions	The diagnosis of postoperative cognitive dysfunction is based on the evaluation of differences in preoperative and postoperative cognitive performance. One of the most commonly used methods for assessing cognitive functions is the Mini-Mental State Examination (MMSE). The MMSE covers subheadings such as orientation, memory, language, attention, calculation, and recall, and is scored out of 30 points. Results are interpreted as follows: 24-30 points indicate normal cognitive function, 18-23 points indicate mild cognitive impairment, and 0-17 points indicate moderate to severe cognitive impairment.	2 hours before the operation and on the first postoperative day, The MMSE test was administered again to patients and the results were recorded.
Evaluate changes in perfusion index (PI)	Perfusion index (PI) is defined as the ratio of the pulsatile signal obtained by photoplethysmography to the nonpulsatile signal. Photoplethysmography is a noninvasive, rapidly applicable method widely used in intraoperative patient monitoring. PI is an indirect indicator of central and peripheral perfusion and is primarily determined by the sympathetic-parasympathetic balance that regulates cardiac output and vascular tone. Changes in PI were evaluated at different applied PEEP levels.	Baseline, 1 minute after anesthesia induction; 1 minute after intubation; 1 minute before pneumoperitoneum;at 1, 5, 10, 15, 30, 45, 60, 90, 120 and 150 minutes after pneumoperitoneum;1 minutes after at the end of pneumoperitoneum, surgery and extubation.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Evaluate changes in near infrared spectroscopy (NIRS)	NIRS is a method that uses near-infrared spectroscopy technology to noninvasively assess the oxygenation status of tissues. In NIRS monitoring, an initial rSO₂ level below 40% or a decrease of more than 25% from the baseline measurement is considered indicative of cerebral ischemia. Changes in NIRS were evaluated at different applied PEEP levels.	Baseline, 1 minute after anesthesia induction; 1 minute after intubation; 1 minute before pneumoperitoneum;at 1, 5, 10, 15, 30, 45, 60, 90, 120 and 150 minutes after pneumoperitoneum;1 minutes after at the end of pneumoperitoneum, surgery and extubation.
To determine the possible correlations between NIRS and hemodynamic data		Baseline, 1 minute after anesthesia induction; 1 minute after intubation; 1 minute before pneumoperitoneum;at 1, 5, 10, 15, 30, 45, 60, 90, 120 and 150 minutes after pneumoperitoneum;1 minutes after at the end of pneumoperitoneum, surgery and extubation.
To determine the possible correlations between PI and hemodynamic data		Baseline, 1 minute after anesthesia induction; 1 minute after intubation; 1 minute before pneumoperitoneum;at 1, 5, 10, 15, 30, 45, 60, 90, 120 and 150 minutes after pneumoperitoneum;1 minutes after at the end of pneumoperitoneum, surgery and extubation.
To determine the possible correlations between PI and MMSE scores	PI was recorded before and after anesthesia induction; 1 minute after intubation; before pneumoperitoneum; at 1, 5, 10, 15, 30, 45, 60, 90, 120 and 150 minutes after pneumoperitoneum; and at the end of pneumoperitoneum and surgery. MMSE was assessed 2 hours before surgery and on postoperative day 1.	2 hours before surgery through postoperative day 1

Collaborators and Investigators

• Sponsor: Ankara City Hospital Bilkent

Study record dates

Study Major Dates

• Study Start (Actual): April 2, 2025
• Primary Completion (Actual): August 15, 2025
• Study Completion (Actual): August 29, 2025

Study Registration Dates

• First Submitted: February 18, 2026
• First Submitted That Met QC Criteria: March 27, 2026
• First Posted (Actual): April 1, 2026

Study Record Updates

• Last Update Posted (Actual): April 1, 2026
• Last Update Submitted That Met QC Criteria: March 27, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Near Infrared Spectroscopy; Laparoscopic Cholecystectomy; Positive End-Expiratory Pressure; Perfusion Index; Geriatric Patient; Post-Operative Cognitive Dysfunction
• Other Study ID Numbers: Geriatric and PEEP

Drug and device information, study documents

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