The Role of Oxygen Reserve Index (ORi) in Apneic Ventilation

NCT ID: NCT07119866

Last Updated: 2025-08-13

Basic Information

• Recruitment Status: NOT_YET_RECRUITING
• Total Enrollment: 60 participants
• Study Classification: OBSERVATIONAL
• Study Start Date: 2025-08-07
• Study Completion Date: 2025-08-30

Brief Summary

Background: The Oxygen Reserve Index (ORI) is a non-invasive parameter utilizing multi-wavelength pulse co-oximetry. ORI can provide early warnings of deteriorating oxygenation before changes are reflected in SpO₂ levels. This study aimed to investigate the feasibility of non-ventilated intubation in patients undergoing cholecystectomy as a means to achieve safe intubation without nasogastric tube placement, with reduced trauma and cost, and improved time efficiency.

Detailed Description

Obesity is a complex and chronic disease that significantly impacts respiratory physiology. It leads to increased work of breathing and reduced compliance of the chest wall. In morbidly obese individuals, there is a marked reduction in total lung capacity, vital capacity, forced expiratory volume in one second (FEV1), and forced vital capacity (FVC). Additionally, due to their elevated metabolic demands, these patients exhibit higher oxygen consumption rates.

The Oxygen Reserve Index (ORi) (Masimo Corp., Irvine, CA, USA) is an advanced, continuous, and non-invasive parameter that provides a relative indication of arterial partial pressure of oxygen (PaO₂).

ORI monitoring can be particularly beneficial in patients at risk for inadequate preoxygenation, those with difficult mask ventilation, hypoxemic patients with aspiration risk, rapid sequence induction scenarios, obese individuals, ICU intubations, and invasive ventilation cases. It has also been shown to provide early warnings of desaturation in select patient groups, contributing to improved patient safety.

Conditions

Oxygen Reserve Index; Apnea; Ventilation; Body Mass Index

Study Design

• Observational Model Type: OTHER
• Study Time Perspective: PROSPECTIVE

Study Groups

ORI>0.24

Patients, aged between 18 and 60 years, classified as ASA physical status I-II,and with a Mallampati score \<2, were enrolled.On the day of surgery, following identity verification and confirmation of the surgical site, patients were positioned on a warmed operating table.Standard monitoring was applied, including ECG, SBP and DBP, SpO₂, and the ORI.Preoxygenation was achieved by administering 100% oxygen via 8 deep breaths over 60 seconds.When the ORI value reached 0.4, intravenous anesthesia induction was initiated using propofol 2 mg/kg, fentanyl 2 mcg/kg, and rocuronium 0.6mg/kg.During muscle relaxation, patients were not ventilated via mask.The ORI value at the time of induction and at the 2nd minute post-induction was recorded.If the ORI dropped below 0.24 before the 2-minute mark, mask ventilation was initiated, and the time of intervention was noted.Endotracheal intubation was then performed using a standard,atraumatic technique after achieving adequate muscle relaxation.

OXYGEN RESERVE INDEX

Intervention Type: OTHER

Noted for each patient.

ORI<0.24

Patients, aged between 18 and 60 years, classified as ASA physical status I-II,and with a Mallampati score \<2, were enrolled.On the day of surgery, following identity verification and confirmation of the surgical site, patients were positioned on a warmed operating table.Standard monitoring was applied, including ECG, SBP and DBP, SpO₂, and the ORI.Preoxygenation was achieved by administering 100% oxygen via 8 deep breaths over 60 seconds.When the ORI value reached 0.4, intravenous anesthesia induction was initiated using propofol 2 mg/kg, fentanyl 2 mcg/kg, and rocuronium 0.6mg/kg.During muscle relaxation, patients were not ventilated via mask.The ORI value at the time of induction and at the 2nd minute post-induction was recorded.If the ORI dropped below 0.24 before the 2-minute mark, mask ventilation was initiated, and the time of intervention was noted.Endotracheal intubation was then performed using a standard,atraumatic technique after achieving adequate muscle relaxation.

OXYGEN RESERVE INDEX

Intervention Type: OTHER

Noted for each patient.

Interventions

OXYGEN RESERVE INDEX

Noted for each patient.

Intervention Type: OTHER

Eligibility Criteria

Inclusion Criteria

• 18-60 years
• ASA 1-2
• Mallampati score <2
• Scheduled for elective laparoscopic cholecystectomy under general anesthesia

Exclusion Criteria

• <18 and >60 years
• ASA 3-4
• Initial ORI value below 0.24

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 60 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Ankara City Hospital Bilkent

OTHER

Sponsor Role: lead

Responsible Party

Ayça Özcan

Prof.

Responsibility Role: PRINCIPAL_INVESTIGATOR

Locations

Ankara Bilkent City Hospital

Ankara, çankaya, Turkey (Türkiye)

Countries

Turkey (Türkiye)

Central Contacts

Ayşegül Özel Erdem

Role: CONTACT

aysegulozell@gmail.com

05549777289

Ayça Özcan

Role: CONTACT

draycaozcan@gmail.com

05057154125

Other Identifiers

Oxygen Reserve Index

Identifier Type: -

Identifier Source: org_study_id