Oxygen Reserve Index in Laparoscopic Colorectal Surgery

Comparison of the Effects of 100% and 80% Oxygen Use During Extubation on Oxygen Reserve Index in Laparoscopic Colorectal Surgery

During laparoscopic procedures, certain physiological changes occur due to the creation of pneumoperitoneum. One such change is the reduction in portal venous blood flow, which can lead to decreased liver perfusion and acute liver cell injury. Additionally, due to an increased alveolar-arterial oxygen pressure gradient, postoperative atelectasis may occur, leading to hypoxia.

In other words, the increased intra-abdominal pressure during laparoscopic surgery-along with the effects of patient positioning and mechanical ventilation used during anesthesia-can worsen low blood oxygen levels, especially in patients with already reduced lung compliance and higher metabolic demands. This makes close monitoring of oxygenation crucial.

The Oxygen Reserve Index (ORI) is a relatively new tool that can help monitor both high oxygen levels (hyperoxemia) and drops in oxygen (desaturation) before they become clinically apparent. Studies have shown that ORI values range from 0 to 1, with an ORI of 0 typically corresponding to a PaO₂ level between 80-125 mmHg. A downward trend in ORI can act as an early warning sign of hypoxemia, giving clinicians a chance to act before it's too late.

Many studies have highlighted the potential harms of using high oxygen concentrations during surgery. For example, while most hospitals still give patients 100% oxygen before anesthesia (a process called preoxygenation), recent evidence suggests this might increase the risk of atelectasis. Therefore, using 80% or less oxygen is now being recommended in many settings. High oxygen levels have also been linked to increased oxidative stress in the body.

In this study, we aim to investigate whether monitoring ORI during extubation can help us detect and prevent both hyperoxemia and hypoxemia-situations that standard pulse oximetry often misses. We plan to compare two groups of patients: one receiving conventional 100% oxygen during extubation, and another receiving 80% oxygen. By monitoring ORI values in both groups, we hope to better understand how different oxygen levels affect patient safety and outcomes.

Study Overview

• Status: Completed
• Conditions: Laparoscopic Colorectal Surgery
• Intervention / Treatment: Behavioral: Oxygen Administration During Extubation

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

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Kartal
    • Istanbul, Kartal, Turkey (Türkiye), 34865
      • Kartal Dr. Lütfi Kırdar Eğitim ve Araştırma hastanesi

Participation Criteria

Eligibility Criteria

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

• Sampling Method: Probability Sample

Study Population

Sixty volunteer patients, aged between 18 and 75, with a Body Mass Index (BMI) below 35 and ASA class I and II, who are scheduled to undergo laparoscopic hysterectomy, will be included.

Description

Inclusion Criteria:

• Age: 18-75
• ASA: I-II
• Scheduled for elective laparoscopic surgery
• BMI <35

Exclusion Criteria:

• Patients undergoing emergency surgery due to trauma
• Patients with ASA physical status classification III or IV
• Patients requiring intensive care unit admission
• Patients with active, clinically symptomatic anemia
• Patients with heart failure
• Patients with known allergy to the sensor material to be used
• Patients with difficult mask ventilation or difficult intubation
• Patients with a platelet count below 30,000/mm³
• Patients with a history of gastrointestinal bleeding within the past 6 months
• Patients with a history of bleeding diathesis or increased risk of intracerebral hemorrhage
• Patients with oliguria and/or those who required dialysis or underwent dialysis within one month prior to surgery
• Patients with a known hypersensitivity reaction to any anesthetic or analgesic drug used in the study
• Patients who do not wish to participate in the study

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Group 1 - 100% Oxygen Group; Patients in this group will receive 100% oxygen during tracheal extubation in laparoscopic colorectal surgery. Oxygenation will be monitored continuously using the Oxygen Reserve Index (ORI) and arterial PaO₂. The intervention is non-invasive and administered via standard anesthesia breathing systems.	Behavioral: Oxygen Administration During Extubation; This intervention involves the administration of oxygen during tracheal extubation in patients undergoing laparoscopic surgery. Two different oxygen concentrations are compared: the control group receives 100% oxygen, while the study group receives 80% oxygen during the extubation phase. All patients are monitored using the Oxygen Reserve Index (ORI) to assess oxygenation status continuously. The goal is to evaluate the effect of oxygen concentration on peri-extubation hyperoxia and hypoxia, as detected by ORI values. The intervention is non-invasive and administered via standard anesthesia breathing systems.
Group 2 - 80% Oxygen Group; Patients in this group will receive 80% oxygen during tracheal extubation in laparoscopic colorectal surgery. Oxygenation will be monitored continuously using the Oxygen Reserve Index (ORI) and arterial PaO₂. The intervention is non-invasive and administered via standard anesthesia breathing systems.	Behavioral: Oxygen Administration During Extubation; This intervention involves the administration of oxygen during tracheal extubation in patients undergoing laparoscopic surgery. Two different oxygen concentrations are compared: the control group receives 100% oxygen, while the study group receives 80% oxygen during the extubation phase. All patients are monitored using the Oxygen Reserve Index (ORI) to assess oxygenation status continuously. The goal is to evaluate the effect of oxygen concentration on peri-extubation hyperoxia and hypoxia, as detected by ORI values. The intervention is non-invasive and administered via standard anesthesia breathing systems.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Oxygen Reserve Index (ORI ) at 5 minutes post-extubation	Oxygen Reserve Index (ORI) will be continuously monitored using a Masimo Radical-7 pulse co-oximeter from the time of extubation until 60 minutes post-extubation. The ORI value recorded at the 5th minute after tracheal extubation will be used for primary outcome analysis.	ORI will be recorded at 5 minutes post-extubation using a Masimo Radical-7 pulse co-oximeter to assess peri-extubation oxygen reserve.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Peripheral Oxygen Saturation (SpO₂, %) trends during and after extubation		Continuous monitoring during and up to 60 minutes after tracheal extubation
Arterial oxygen partial pressure (PaO₂, mmHg) at 5 minutes post-extubation	Arterial blood gas analysis will be performed to measure PaO₂ and evaluate early postoperative oxygenation status following extubation.	5 minutes after tracheal extubation
Oxygen Reserve Index (ORI) at 60 minutes post-extubation	ORI will be continuously monitored from extubation until 60 minutes post-extubation using a Masimo Radical-7 device. The ORI value at the 60th minute will be recorded to assess sustained postoperative oxygen reserve.	60 minutes after tracheal extubation
Arterial oxygen partial pressure (PaO₂, mmHg) at 60 minutes post-extubation	Arterial blood gas analysis will be used to measure PaO₂ at 60 minutes post-extubation to evaluate sustained oxygenation differences between study groups.	60 minutes after tracheal extubation
Heart rate during the first postoperative hour	Heart rate will be continuously monitored to evaluate hemodynamic stability during emergence and the early postoperative period.	From extubation until 60 minutes post-extubation
Mean arterial pressure (mmHg) during the first postoperative hour	Mean arterial pressure will be continuously monitored to assess hemodynamic changes during emergence and the early postoperative period.	From extubation until 60 minutes post-extubation

Collaborators and Investigators

• Sponsor: Dr. Lutfi Kirdar Kartal Training and Research Hospital

Study record dates

Study Major Dates

• Study Start (Actual): January 7, 2025
• Primary Completion (Actual): December 30, 2025
• Study Completion (Actual): February 10, 2026

Study Registration Dates

• First Submitted: September 19, 2025
• First Submitted That Met QC Criteria: February 25, 2026
• First Posted (Actual): March 3, 2026

Study Record Updates

• Last Update Posted (Actual): March 3, 2026
• Last Update Submitted That Met QC Criteria: February 25, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: extubation; laparoscopic colorectal surgery; ORİ; FİO2; pao2
• Other Study ID Numbers: 2025/01/990

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

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