An observational study in Oxygen Reserve Index, Apnea and Ventilation, sponsored by Ankara City Hospital Bilkent. Not yet recruiting at 1 site in Turkey (Türkiye). Open to participants aged 18 Years to 60 Years. Per ClinicalTrials.gov, last updated 2025-08-13.
Sponsored by Ankara City Hospital Bilkent · Observational
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.
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.
282 studies on the registry are indexed under Apnea; 54 are open to participants now.
This study's planned enrollment of 60 is close to the median of 60 across 78 observational studies indexed under Apnea.
Browse Apnea studies →Ankara City Hospital Bilkent is the lead sponsor of 443 studies on the registry; 111 are open to participants now.
Counted across the registry records on this site, refreshed daily.
60 patients between the ages of 18-60 years, ASA 1-2, scheduled for elective laparoscopic cholecystectomy under general anesthesia.
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Exclusion Criteria:
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.
Other: OXYGEN RESERVE INDEX
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.
Other: OXYGEN RESERVE INDEX
Noted for each patient.
TIME FOR ORI TO FALL BELOW 0.24
TIME THE PATIENT STARTED TO WEAR A MASKS.
Time frame: WITHIN 10 MINUTES BEFORE INTUBATION
INITIAL ORI VALUE
Noted for each patient.
Time frame: WITHIN 10 MINUTES BEFORE INTUBATION
ORI VALUE AT 2 MINUTES
Noted for each patient.
Time frame: WITHIN 10 MINUTES BEFORE INTUBATION
AGE
Noted for each patient.
Time frame: WITHIN 10 MINUTES BEFORE INTUBATION
American Society of Anesthesiologists (ASA) Score
Noted for each patient.
Time frame: WITHIN 10 MINUTES BEFORE INTUBATION
SEX
Noted for each patient.
Time frame: WITHIN 10 MINUTES BEFORE INTUBATION
BMI
Noted for each patient.
Time frame: WITHIN 10 MINUTES BEFORE INTUBATION
PRESENCE OF A NASOGASTRIC TUBE
Noted for each patient.
Time frame: 10 MINUTES BEFORE EXTUBATION
Surgeon satisfaction
Noted for each patient. Surgeon satisfaction according to ng usage status.
Time frame: 10 MINUTES BEFORE EXTUBATION
PRESENCE OF LARYNGOSPASM
Noted for each patient.
Time frame: 10 MINUTES BEFORE EXTUBATION
Start is estimated for Aug 2025; primary completion for Aug 2025, 0 months later.
Of 35 observational studies under Apnea, half reached primary completion within 23 months of starting (the median), counting those still running; a quarter within 14 and three quarters within 38. This study's planned 0 months is below that.
How these figures are worked out, and which studies are left out of them.
This study is not yet recruiting, as verified in Aug 2025. You cannot join it, but the record below documents what was studied.
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