Evaluation of Oxygen Reserve Index (ORi) in Obese and Non-Obese Patients Over 65 Years Old

NCT07679724 | Completed

• 1 other identifier: AnkaraCHBilkent-AR-CT-01
• Study Type: observational
• Target: 90
• Locations: 1 country
• Sites: 1

Brief Summary

After obtaining ethical committee approval, this single-center, prospective, observational study included volunteer patients of both sexes, aged 65 years and older, with ASA II-III risk scores, who were scheduled for elective surgery with endotracheal intubation under general anesthesia (GAA). 90 patients were divided into two groups: those with normal BMI (19 \< BMI \< 25 kg/m² (GROUP 1)) and those who were obese (30 \< BMI \< 40 kg/m² (GROUP 2)). In addition to standard ASA monitoring, a finger sensor (Rainbow® SET, Masimo Inc., Irvine, Ca., USA) was implanted for ORi measurement, and baseline values were recorded. Patients were preoxygenated until EtO2 (endtidal oxygen) concentration reached at least 85%. After ORi reached a plateau level, general anesthesia was induced and endotracheal intubation was performed. After confirming the tube's position, the breathing circuit was disconnected from the endotracheal tube, and patients were allowed to be apneic until SpO2 reached 94%. Throughout this process, patients' other vital signs, SpO₂, and ORi were continuously monitored. The time elapsed when ORi triggered an alarm, when SpO2 reached 97%, and when SpO2 reached 94% was recorded. The 'ORi warning time', 'SpO2 warning time', and the 'additional warning time provided by ORi' (the difference between 'ORi warning time' and 'SpO2 warning time') were recorded.

Conditions

Obesity &Amp;Amp; Overweight; Elderly (People Aged 65 or More); Oxygen Reserve Index

Outcome Measures

Primary Outcomes (1)

• Oxygen reserve index (ORi) warning time, SpO2 warning time, and added warning time defined as the difference between the two

  The primary aim of this study was to determine whether ORi provides an early warning of impending desaturation compared to pulse oximetry in both obese (30 \< BMI \< 40 kg/m²) and normal body mass index (19 \< BMI \< 25 kg/m²) patients over 65 years of age scheduled for elective surgery will be assesed until SpO2 drops to 94%

  15 minutes after preoxygenation

Secondary Outcomes (1)

• Oxygen reserve index (ORi) warning time, SpO2 warning time, and added warning time defined as the difference between the two

  15 minutes after preoxygenation

Study Arms (2)

Group 1

Patients with normal BMI (19 \< BMI \< 25 kg/m²)

Group 2

Obese patients (30 \< BMI \< 40 kg/m² )

Eligibility Criteria

• Age: 65 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

90 patients aged 65 and over, ASA II-III

You may qualify if:

• Patients of both sexes aged 65 years and older with ASA II-III risk scores who are scheduled to undergo elective surgical procedures with endotracheal intubation under general anesthesia.

You may not qualify if:

• Patients under 65 years of age
• Patients with heart and lung disease
• Patients in situations where the patient is unable to cooperate (e.g., dementia, Alzheimer's)
• Patients suspected of having airway difficulties

Sponsors & Collaborators

• Ankara City Hospital Bilkent: lead

Study Sites (1)

Ankara Bilkent City Hospital

Ankara, Turkey (Türkiye)

Location

Related Publications (2)

• Tsymbal E, Ayala S, Singh A, Applegate RL 2nd, Fleming NW. Study of early warning for desaturation provided by Oxygen Reserve Index in obese patients. J Clin Monit Comput. 2021 Aug;35(4):749-756. doi: 10.1007/s10877-020-00531-w. Epub 2020 May 18.

  PMID: 32424516 BACKGROUND

• Fleming NW, Singh A, Lee L, Applegate RL 2nd. Oxygen Reserve Index: Utility as an Early Warning for Desaturation in High-Risk Surgical Patients. Anesth Analg. 2021 Mar 1;132(3):770-776. doi: 10.1213/ANE.0000000000005109.

  PMID: 32815872 BACKGROUND

MeSH Terms

Conditions

Obesity; Overweight

Condition Hierarchy (Ancestors)

Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Study Design

• Study Type: observational
• Observational Model: CASE CONTROL
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Medical Doctor

Study Record Dates

• First Submitted: May 2, 2026
• First Posted: July 1, 2026
• Study Start: November 1, 2023
• Primary Completion: May 1, 2024
• Study Completion: July 1, 2024
• Last Updated: July 1, 2026

Record last verified: 2026-06

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)