Apneic Oxygenation, Endolarengeal Surgery, Oxygen Reserve Index
Conditions
Keywords
oxygen reserve index, pulse oximetry, apneic ventilation
Brief summary
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.
Detailed description
This prospective, single-center, randomized clinical trial was designed to evaluate the role of the Oxygen Reserve Index (ORi) in the early detection of hypoxemia during apneic intermittent ventilation in adult patients undergoing elective endolaryngeal surgery under general anesthesia. Endolaryngeal procedures require shared airway management and frequently involve apneic periods, during which conventional pulse oximetry may fail to provide timely warning of declining oxygen reserves due to the plateau phase of the oxyhemoglobin dissociation curve. Eligible patients aged 18 years and older with ASA physical status I-III were randomly assigned to either an ORi-monitored group or a control group monitored with standard peripheral oxygen saturation (SpO₂). All patients underwent standardized anesthesia induction, preoxygenation, and apneic intermittent ventilation. In the ORi group, the threshold for resuming ventilation was defined as ORi reaching zero, whereas in the control group ventilation was resumed when SpO₂ decreased to 90%. The primary outcome was the time from the onset of apnea to the predefined reventilation threshold. Secondary outcomes included arterial blood gas parameters (pH, PaO₂, PaCO₂) at the time of reventilation, end-tidal carbon dioxide levels, perioperative lung ultrasound findings, post-anesthesia care unit length of stay, and postoperative respiratory outcomes. This study aims to 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.
Interventions
PROCEDUREoxygen monitoring techniques
to 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.
Sponsors
Istanbul University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
SINGLE (Subject)
Masking description
Masking Description
Intervention model description
Model Description
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
* 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 * Ability to provide written informed consent
Exclusion criteria
* Age under 18 years * Preoperative chronic hypoxemia (baseline SpO₂ \< 95%) * Patients transferred from the intensive care unit * ASA physical status IV or higher * Refusal or inability to provide informed consent
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Time to Reventilation Threshold | From the onset of apnea until the predefined reventilation threshold is reached during the intraoperative period (within minutes). | 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. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Arterial Blood Gas Parameters at Reventilation | From the onset of apnea until the predefined reventilation threshold is reached during the intraoperative period (within minutes). | Arterial blood gas values including pH, partial pressure of oxygen (PaO₂), and partial pressure of carbon dioxide (PaCO₂) measured at the time of reventilation. |
| Perioperative Lung Ultrasound Findings | Preoperatively (before anesthesia induction) and postoperatively in the post-anesthesia care unit (within 1 hour after surgery). | Change in lung ultrasound (LUS) B-line count between preoperative and postoperative assessments. |
| Postoperative Oxygenation | postoperatively in the post-anesthesia care unit (within 1 hour after surgery). | Lowest peripheral oxygen saturation (SpO₂) recorded during PACU stay. |
| End-Tidal Carbon Dioxide (EtCO₂) Level | During the apneic period, measured at the time of reventilation during surgery. | First recorded EtCO₂ value during apnea prior to reventilation. |
Countries
Turkey (Türkiye)
Contacts
CONTACTDemet Altun, Prof
CONTACTece naz demir, resident
PRINCIPAL_INVESTIGATORece naz demir, resident
Istanbul University
STUDY_DIRECTORdemet altun, prof
Istanbul University
Outcome results
None listed