Can Atelectasis Be Prevented With Oxygen Reserve Index (ORI) Monitoring?

NCT ID: NCT07050719

Last Updated: 2025-12-10

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 58 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2025-07-15
• Study Completion Date: 2025-12-08

Brief Summary

This single-center randomized controlled trial aims to evaluate whether intraoperative monitoring using the Oxygen Reserve Index (ORI) reduces the incidence of postoperative atelectasis, as assessed by lung ultrasound (LUS), in adult patients undergoing elective robotic surgery under general anesthesia.

Detailed Description

Postoperative atelectasis is observed in 60-90% of patients undergoing general anesthesia. Factors such as high inspired oxygen concentration, muscle relaxation, and reduced functional residual capacity contribute to its development through mechanisms like absorption atelectasis. The persistence of atelectasis increases the risk of pneumonia, hypoxia, prolonged hospital stay, healthcare costs, and mortality. Despite the well-known pathophysiology, the optimal intraoperative fraction of inspired oxygen (FiO₂) remains unclear.

The Oxygen Reserve Index (ORI) is a non-invasive, continuous parameter that reflects the oxygen reserve within the moderate hyperoxia range (100-200 mmHg). It may facilitate individualized FiO₂ titration to avoid hyperoxia-related atelectasis. Lung ultrasound (LUS) is a reliable, radiation-free bedside tool for detecting atelectasis.

This study hypothesizes that ORI-guided oxygen therapy will reduce the incidence of postoperative atelectasis compared to standard Peripheral Capillary Oxygen Saturation (SpO₂)-guided therapy.

Conditions

Atelectasis; Lung Ultrasonography Score; Hyperoxia

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: PREVENTION
• Blinding Strategy: TRIPLE

Study Groups

Peripheral Oxygen Saturation (SpO₂) Group

FiO₂ adjusted based on pulse oximetry to maintain SpO₂ ≥98%

Group Type: ACTIVE_COMPARATOR

Peripheral Oxygen Saturation (SpO₂) Group

Intervention Type: PROCEDURE

FiO₂ adjusted based on pulse oximetry to maintain SpO₂ ≥98%

Peripheral Oxygen Saturation and Oxygen Reserve Index (SpO₂-ORI) Group

FiO₂ adjusted using both SpO₂ and ORI to maintain ORI between 0-0.3

Group Type: ACTIVE_COMPARATOR

Peripheral Oxygen Saturation and Oxygen Reserve Index (SpO₂-ORI) Group

Intervention Type: PROCEDURE

FiO₂ adjusted using both SpO₂ and ORI to maintain ORI between 0-0.3

Interventions

Peripheral Oxygen Saturation (SpO₂) Group

FiO₂ adjusted based on pulse oximetry to maintain SpO₂ ≥98%

Intervention Type: PROCEDURE

Peripheral Oxygen Saturation and Oxygen Reserve Index (SpO₂-ORI) Group

FiO₂ adjusted using both SpO₂ and ORI to maintain ORI between 0-0.3

Intervention Type: PROCEDURE

Eligibility Criteria

Inclusion Criteria

• American Society of Anesthesiologists Physical Status Classification System (ASA) physical status I-III
• Elective robotic surgery under general anesthesia
• Surgery duration >2 hours
• Requires invasive arterial cannulation
• Signed informed consent

Exclusion Criteria

• ASA IV or higher
• Room air SpO₂ <92%
• Chronic pulmonary disease
• Hemoglobinopathy
• Pregnancy
• Refusal to participate

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 75 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Antalya Training and Research Hospital

OTHER_GOV

Sponsor Role: lead

Responsible Party

Nilgun Kavrut Ozturk

PROFESSOR MD

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

NILGUN KAVRUT OZTURK, PROFESSOR MD

Role: STUDY_CHAIR

Antalya Training and Research Hospital

AYSE MERVE ERDEM, RESIDENT

Role: PRINCIPAL_INVESTIGATOR

Antalya Training and Research Hospital

Locations

Antalya Training and Research Hospital

Antalya, Muratpasa, Turkey (Türkiye)

Countries

Turkey (Türkiye)

Other Identifiers

AEAHAE001

Identifier Type: -

Identifier Source: org_study_id