Oxygen Reserve Index (ORi) in Identifying Desaturation
Trial statusNot yet recruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age18+
SponsorIstanbul University
About this trial
This randomized clinical trial investigates whether Oxygen Reserve Index (ORi) monitoring enables earlier detection of impending hypoxemia compared with conventional pulse oximetry during apneic intermittent ventilation in adult patients undergoing endolaryngeal surgery under general anesthesia. By providing continuous, noninvasive assessment of oxygen reserve in the hyperoxic range, ORi may offer an earlier warning of oxygen depletion before peripheral oxygen saturation declines. The study compares time to reventilation thresholds, arterial blood gas parameters, and perioperative respiratory outcomes between ORi-guided and standard SpO₂-guided monitoring strategies.
Eligibility criteria
This trial accepts healthy volunteersQualifiers
Age 18 years or older
Scheduled for elective endolaryngeal surgery
Planned general anesthesia with apneic intermittent ventilation
American Society of Anesthesiologists (ASA) physical status I-III
Disqualifiers
Age under 18 years
Preoperative chronic hypoxemia (baseline SpO₂ < 95%)
Patients transferred from the intensive care unit
ASA physical status IV or higher
Trial design
Design model
Parallel
Treatments tested in this trial
oxygen monitoring techniques
Procedure/Surgeryto determine whether ORi monitoring provides earlier and clinically meaningful warning of oxygen reserve depletion compared with conventional pulse oximetry, potentially improving patient safety during shared-airway surgery.
Treatment groups
80 Participants
are divided into 2 treatment groupsGroup A: Oxygen Reserve IndexExperimental treatment 1 intervention
Group B: Peripheral oxygen saturationNo intervention 0 interventions
Trial outcomes
Primary outcomes
1
Time to Reventilation Threshold
Time from the onset of apnea to the predefined reventilation threshold, defined as Oxygen Reserve Index (ORi) reaching zero in the ORi group and peripheral oxygen saturation (SpO₂) decreasing to 90% in the control group, measured in seconds.
Time frame
From the onset of apnea until the predefined reventilation threshold is reached during the intraoperative period (within minutes).Secondary outcomes
1
Arterial Blood Gas Parameters at Reventilation
Arterial blood gas values including pH, partial pressure of oxygen (PaO₂), and partial pressure of carbon dioxide (PaCO₂) measured at the time of reventilation.
Time frame
From the onset of apnea until the predefined reventilation threshold is reached during the intraoperative period (within minutes).2
Perioperative Lung Ultrasound Findings
Change in lung ultrasound (LUS) B-line count between preoperative and postoperative assessments.
Time frame
Preoperatively (before anesthesia induction) and postoperatively in the post-anesthesia care unit (within 1 hour after surgery).3
Postoperative Oxygenation
Lowest peripheral oxygen saturation (SpO₂) recorded during PACU stay.
Time frame
postoperatively in the post-anesthesia care unit (within 1 hour after surgery).4
End-Tidal Carbon Dioxide (EtCO₂) Level
First recorded EtCO₂ value during apnea prior to reventilation.
Time frame
During the apneic period, measured at the time of reventilation during surgery.Sponsors and contacts
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Source ClinicalTrials.gov
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