The Effectiveness of Oxygen Reserve Index in Early Detection of Desaturation in Geriatric Patients Scheduled for Oncological Surgery

NCT ID: NCT07326293

Last Updated: 2026-01-08

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

RECRUITING

Total Enrollment

44 participants

Study Classification

OBSERVATIONAL

Study Start Date

2025-12-16

Study Completion Date

2026-02-16

Brief Summary

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This prospective observational study aims to evaluate the relationship between the Oxygen Reserve Index (ORI) and tolerable apnea time in geriatric patients undergoing elective oncologic surgery under general anesthesia.

Patients aged 65 years and older will be monitored using standard anesthesia monitoring and Masimo Rainbow SET® Pulse CO-Oximetry during anesthesia induction and tracheal intubation.

Tolerable apnea time will be defined as the duration from the end of ventilation after intubation to a decrease in peripheral oxygen saturation (SpO₂) to 94%.

The primary objective is to assess the association between ORI warning time and tolerable apnea time. Secondary objectives include evaluating the association between ORI values, arterial blood gas parameters at predefined time points, and the Clinical Frailty Scale.

Detailed Description

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This study is a prospective, observational study. Patients aged 65 years and older who are scheduled for elective oncologic surgery at Ankara Bilkent City Hospital will be included. In all patients, the Clinical Frailty Scale will be routinely assessed during the preoperative period.

In this study, tolerable apnea time will be defined as the time until peripheral oxygen saturation (SpO₂), measured by pulse oximetry, decreases to 94%. Although SpO₂ values of 90% and above have been accepted in the literature, the World Health Organization defines normal SpO₂ as 95% and above and considers values of 94% and below as an indication for treatment.

The Oxygen Reserve Index (ORI) ranges from 0 to 1, and the ORI alarm value triggered by the device due to a downward trend will be recorded. ORI is a dimensionless index ranging from 1 (high oxygen reserve) to 0 (no oxygen reserve), which is measured by optically detecting changes in venous oxygen saturation (SvO₂) after arterial oxygen saturation (SpO₂) reaches 100%. ORI is measured using a multi-wavelength pulse co-oximeter placed on a fingertip.

In addition to routine anesthesia monitoring, including electrocardiography, pulse oximetry, and hemodynamic monitoring, patients will also be monitored using Masimo Rainbow SET® Pulse CO-Oximetry. Due to the oncologic nature of the surgeries and the associated risk of bleeding, close hemodynamic monitoring is required; therefore, invasive arterial blood pressure monitoring will be established in all patients before anesthesia induction.

All patients will be preoxygenated with 100% oxygen for 3 minutes. After establishing intravenous access, anesthesia induction will be performed using intravenous propofol at a dose of 2 mg/kg and fentanyl at a dose of 1 µg/kg. Neuromuscular blockade will be achieved with rocuronium at a dose of 0.6 mg/kg.

All patients will be intubated by an experienced anesthesiologist using a videolaryngoscope. Oxygen Reserve Index (ORI) and peripheral oxygen saturation (SpO₂) values will be recorded, and arterial blood gas analyses will be performed at five predefined time points: baseline (initial values), after 3 minutes of preoxygenation, after 2 minutes of bag-mask ventilation following intubation, during apnea when SpO₂ decreases to 94% without ventilation, and after 2 minutes of ventilation with 100% oxygen.

ORI warning time will be defined as the interval from the onset of the ORI alarm to the decrease of SpO₂ to 94%. SpO₂ warning time will be defined as the duration of the decrease in SpO₂ from 97% to 94%.

Conditions

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Desaturation Apnea, Hypoxia Oxygen Reserve Index

Study Design

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Observational Model Type

COHORT

Study Time Perspective

PROSPECTIVE

Eligibility Criteria

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Inclusion Criteria

Records of patients aged 65 years and older, classified as ASA physical status I-III, who are scheduled for elective oncologic surgery.

Exclusion Criteria

Records of patients with advanced coronary artery disease; advanced heart failure and/or valvular heart disease; carotid artery stenosis; left ventricular ejection fraction below 30%; rapid atrial fibrillation; body mass index (BMI) greater than 35 kg/m²; anticipated difficult airway; advanced-stage malignancy; or dementia.
Minimum Eligible Age

65 Years

Maximum Eligible Age

100 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

No

Sponsors

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Ankara City Hospital Bilkent

OTHER

Sponsor Role lead

Responsible Party

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Responsibility Role SPONSOR

Locations

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Ankara Bilkent City Hospital

Ankara, Çankaya, Turkey (Türkiye)

Site Status RECRUITING

Countries

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Turkey (Türkiye)

Central Contacts

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Muhlis Kuru

Role: CONTACT

+905312089322

Facility Contacts

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Muhlis Kuru

Role: primary

+905312089322

Other Identifiers

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E2-24-8204

Identifier Type: -

Identifier Source: org_study_id

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