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Hyperoxemia and Oxygen Reserve Index During Neurointerventional Anesthesia

30 septembre 2026 mis à jour par: Cansu Ofluoğlu, Fatih Sultan Mehmet Training and Research Hospital

Arterial Hyperoxemia and Oxygen Reserve Index During Elective Neurointerventional Procedures Under General Anesthesia: A Prospective Observational Study

The goal of this observational study is to learn how often high blood oxygen levels (hyperoxemia) occur in adults receiving general anesthesia for planned (elective) neurointerventional procedures, such as brain aneurysm coiling or other catheter-based treatments of brain vessels. It will also look at how well a non-invasive finger sensor measurement called the Oxygen Reserve Index (ORi) reflects arterial oxygen levels.

The main questions it aims to answer are:

  • How often is the arterial oxygen pressure (PaO2) 150 mmHg or higher in blood gas samples taken as part of routine care during these procedures?
  • How does ORi relate to PaO2, and can ORi help identify high oxygen levels?

Participants will:

  • Receive anesthesia and their procedure exactly as planned by their care team; the study does not change any treatment, oxygen setting, or ventilator setting.
  • Have a painless ORi sensor placed on a finger, similar to a standard pulse oximeter, during anesthesia.
  • Have their routine monitoring values and the results of arterial blood gas samples taken for routine clinical care recorded.

No extra blood samples will be taken for the study, and ORi values will not be used to guide care.

Aperçu de l'étude

Statut

Pas encore de recrutement

Les conditions

Intervention / Traitement

Description détaillée

Background and rationale:

Oxygen is routinely given during general anesthesia to prevent hypoxemia. However, oxygen given beyond the patient's needs may cause arterial hyperoxemia, which has been linked to vasoconstriction, oxidative stress, and absorption atelectasis. Normobaric hyperoxia has been shown to reduce cerebral blood flow, and cumulative hyperoxemia exposure has been associated with unfavorable outcomes in ventilated patients with aneurysmal subarachnoid hemorrhage. Although these findings come from critically ill populations, they provide a physiological rationale for describing arterial oxygen levels in patients undergoing elective neurointerventional procedures, in whom maintaining cerebral perfusion is essential.

Standard pulse oximetry (SpO2) plateaus at high arterial oxygen levels and cannot detect hyperoxemia. The Oxygen Reserve Index (ORi) is a continuous, non-invasive, dimensionless index (0 to 1) derived from multi-wavelength pulse co-oximetry, reported to reflect oxygenation changes in the moderately hyperoxic range (approximately PaO2 100-200 mmHg). The ORi-PaO2 relationship varies across populations and clinical settings, and it has not been described in stable adults undergoing elective neurointerventional procedures under general anesthesia.

Study design:

This is a single-center, prospective, observational study conducted at the Department of Anesthesiology and Reanimation and the Interventional Radiology Unit of University of Health Sciences Fatih Sultan Mehmet Training and Research Hospital, Istanbul, Türkiye. No randomization, group allocation, or clinical intervention will be performed.

Procedures:

Anesthesia induction and maintenance, ventilator settings, FiO2, fluids, vasoactive drugs, and all other management will follow the attending anesthesiologist's routine practice. In addition to standard monitoring, an ORi-capable pulse co-oximetry sensor will be applied. ORi values will be recorded by the investigator but will not be used for clinical decision-making, and no changes in FiO2, ventilation, or treatment will be made based on ORi.

ORi, SpO2, FiO2, heart rate, mean arterial pressure, end-tidal carbon dioxide, body temperature, perfusion index, and signal quality will be recorded at the following time points: 5 minutes after intubation and initiation of mechanical ventilation (T1), 30 minutes (T2) and 60 minutes (T3) after the start of the procedure, every 60 minutes thereafter starting at 120 minutes if the procedure continues (T4 onward), and at the end of the procedure before FiO2 is increased for emergence (Tend).

Whenever an arterial blood gas sample is drawn by the clinical team for routine care, PaO2, PaCO2, pH, SaO2, hemoglobin, and lactate will be recorded and matched with ORi, SpO2, FiO2, perfusion index, and hemodynamic values recorded at the time of sampling or within 1 minute. No additional blood samples will be drawn for research purposes, and the timing and number of routine samples will not be altered.

Patients without a routine arterial blood gas will remain in the cohort for descriptive analyses; PaO2-based analyses will include all valid matched ORi-PaO2 pairs.

Sample size and statistical analysis:

Assuming an expected hyperoxemia proportion of 50%, a 95% confidence level, and a precision of +/-10%, the minimum required sample size is 96 patients; 100 patients will be enrolled to account for missing data. The proportion of matched measurements with PaO2 >=150 mmHg will be reported with 95% confidence intervals. Repeated measurements will be analyzed with mixed-effects models. The ORi-PaO2 relationship, including possible nonlinearity and plateau behavior, will be evaluated with appropriate regression models. The ability of ORi to discriminate PaO2 >=150 and >=200 mmHg will be explored with ROC analysis, accounting for within-patient clustering. A p value <0.05 will be considered statistically significant.

Data protection:

All data will be de-identified, recorded on study case report forms, and used by the study team for scientific purposes only.

Type d'étude

Observationnel

Inscription (Estimé)

100

Contacts et emplacements

Cette section fournit les coordonnées de ceux qui mènent l'étude et des informations sur le lieu où cette étude est menée.

Coordonnées de l'étude

Lieux d'étude

      • Istanbul, Turquie (Türkiye), 34000
        • University of Health Sciences Fatih Sultan Mehmet Training and Research Hospital Scientific Research
        • Contact:

Critères de participation

Les chercheurs recherchent des personnes qui correspondent à une certaine description, appelée critères d'éligibilité. Certains exemples de ces critères sont l'état de santé général d'une personne ou des traitements antérieurs.

Critère d'éligibilité

Âges éligibles pour étudier

18 ans et plus (Adulte, Adulte plus âgé)

Accepte les volontaires sains

Non

Sexes éligibles pour l'étude

Tout

Méthode d'échantillonnage

Échantillon non probabiliste

Population étudiée

Adult patients (ASA I-III) scheduled for elective neurointerventional procedures under general anesthesia with routine invasive arterial monitoring at the Interventional Radiology Unit of University of Health Sciences Fatih Sultan Mehmet Training and Research Hospital, Istanbul, Türkiye. Eligible patients will be enrolled consecutively.

La description

Inclusion Criteria:

  • Age 18 years or older
  • American Society of Anesthesiologists (ASA) physical status I-III
  • Scheduled for an elective neurointerventional procedure
  • Procedure performed under general anesthesia
  • Invasive arterial pressure monitoring and arterial blood gas sampling planned as part of routine clinical care
  • Written informed consent obtained from the patient or, when required, the legal representative

Exclusion Criteria:

  • Refusal to participate
  • Emergency neurointerventional procedure
  • ASA physical status IV or higher
  • Pregnancy
  • Mechanical ventilation before the procedure
  • Chronic respiratory failure requiring long-term home oxygen therapy
  • Severe peripheral circulatory impairment or technical signal failure preventing reliable ORi measurement

Plan d'étude

Cette section fournit des détails sur le plan d'étude, y compris la façon dont l'étude est conçue et ce que l'étude mesure.

Comment l'étude est-elle conçue ?

Détails de conception

  • Modèles d'observation: COHORT
  • Perspectives temporelles: PROSPECTIVE

Cohortes et interventions

Groupe / Cohorte
Intervention / Traitement
Elective Neurointerventional Procedures Under General Anesthesia

Adult patients (ASA I-III) undergoing elective neurointerventional procedures under general anesthesia with routine invasive arterial pressure monitoring. All anesthetic, ventilatory, and oxygen management follows routine clinical practice. An ORi-capable pulse co-oximetry sensor is applied for observational recording only; ORi values are not used for clinical decisions. Routine monitoring data and results of arterial blood gas samples drawn for clinical care are recorded. No additional blood samples are taken for research purposes.

Non-invasive ORi measurement via multi-wavelength pulse co-oximetry, recorded blinded to the anesthesia team and not used to guide care.

Que mesure l'étude ?

Principaux critères de jugement

Mesure des résultats
Description de la mesure
Délai
Proportion of Matched Arterial Blood Gas Measurements With PaO2 >=150 mmHg
Délai: Intraoperative period, from intubation to the end of the procedure before FiO2 is increased for emergence (approximately 1-4 hours)

Number of valid matched ORi-PaO2 measurement pairs with PaO2 >=150 mmHg divided by the total number of valid matched pairs, multiplied by 100. Only arterial blood gas samples drawn for routine clinical care and matched to a valid ORi value recorded at the time of sampling or within 1 minute are included. Reported with 95% confidence interval.

Intraoperative period, from intubation to the end of the procedure before FiO2 is increased for emergence (approximately 1-4 hours)

Mesures de résultats secondaires

Mesure des résultats
Description de la mesure
Délai
Proportion of Matched Arterial Blood Gas Measurements With PaO2 >=200 mmHg
Délai: Intraoperative period, from intubation to the end of the procedure before FiO2 is increased for emergence (approximately 1-4 hours)

Number of valid matched ORi-PaO2 pairs with PaO2 >=200 mmHg divided by the total number of valid matched pairs, multiplied by 100, reported with 95% confidence interval.

Intraoperative period, from intubation to the end of the procedure before FiO2 is increased for emergence (approximately 1-4 hours)
Proportion of Patients With at Least One PaO2 >=150 mmHg and >=200 mmHg Measurement
Délai: Intraoperative period, from intubation to the end of the procedure before FiO2 is increased for emergence (approximately 1-4 hours)

Percentage of patients with at least one valid matched arterial blood gas measurement showing PaO2 >=150 mmHg, and separately >=200 mmHg, among patients with at least one valid matched measurement.

Intraoperative period, from intubation to the end of the procedure before FiO2 is increased for emergence (approximately 1-4 hours)
Per-Patient Proportion of Hyperoxemic Measurements
Délai: Intraoperative period, from intubation to the end of the procedure before FiO2 is increased for emergence (approximately 1-4 hours)

For each patient, the number of matched measurements with PaO2 >=150 mmHg (and >=200 mmHg) divided by that patient's total number of matched measurements, summarized across patients.

Intraoperative period, from intubation to the end of the procedure before FiO2 is increased for emergence (approximately 1-4 hours)
Perioperative Changes in ORi, SpO2, FiO2, and Hemodynamic Parameters
Délai: Intraoperative period, from intubation to the end of the procedure before FiO2 is increased for emergence (approximately 1-4 hours)

ORi (dimensionless, 0-1), SpO2 (%), FiO2 (%), heart rate (beats/min), mean arterial pressure (mmHg), end-tidal CO2 (mmHg), body temperature (degrees C), and perfusion index recorded at T1 (5 min after intubation), T2 (30 min), T3 (60 min), every 60 min thereafter from 120 min, and Tend (end of procedure before FiO2 increase). Changes over time analyzed with mixed-effects models.

Intraoperative period, from intubation to the end of the procedure before FiO2 is increased for emergence (approximately 1-4 hours)
Relationship Between ORi and PaO2
Délai: Intraoperative period, from intubation to the end of the procedure before FiO2 is increased for emergence (approximately 1-4 hours)

Association between ORi and PaO2 in matched measurement pairs, evaluated with linear and nonlinear regression models accounting for repeated measurements within patients, including assessment of a possible plateau in ORi at higher PaO2 values.

Intraoperative period, from intubation to the end of the procedure before FiO2 is increased for emergence (approximately 1-4 hours)
Discriminative Ability of ORi for PaO2 >=150 mmHg and >=200 mmHg
Délai: Intraoperative period, from intubation to the end of the procedure before FiO2 is increased for emergence (approximately 1-4 hours)

Area under the receiver operating characteristic curve (AUROC) of ORi for detecting PaO2 >=150 mmHg and >=200 mmHg in matched pairs, with optimal cut-off, sensitivity, and specificity. Exploratory analysis accounting for within-patient clustering.

Intraoperative period, from intubation to the end of the procedure before FiO2 is increased for emergence (approximately 1-4 hours)
Factors Associated With Hyperoxemia
Délai: Intraoperative period, from intubation to the end of the procedure before FiO2 is increased for emergence (approximately 1-4 hours)

Association of hyperoxemia (PaO2 >=150 mmHg) with patient characteristics (age, sex, body mass index, ASA class, comorbidities), anesthesia characteristics (FiO2, anesthesia duration), and procedure characteristics (procedure type, duration, contrast volume), evaluated with multivariable mixed-effects models.

Intraoperative period, from intubation to the end of the procedure before FiO2 is increased for emergence (approximately 1-4 hours)

Collaborateurs et enquêteurs

C'est ici que vous trouverez les personnes et les organisations impliquées dans cette étude.

Parrainer

Dates d'enregistrement des études

Ces dates suivent la progression des dossiers d'étude et des soumissions de résultats sommaires à ClinicalTrials.gov. Les dossiers d'étude et les résultats rapportés sont examinés par la Bibliothèque nationale de médecine (NLM) pour s'assurer qu'ils répondent à des normes de contrôle de qualité spécifiques avant d'être publiés sur le site Web public.

Dates principales de l'étude

Début de l'étude (Estimé)

1 octobre 2026

Achèvement primaire (Estimé)

1 avril 2027

Achèvement de l'étude (Estimé)

1 avril 2027

Dates d'inscription aux études

Première soumission

30 septembre 2026

Première soumission répondant aux critères de contrôle qualité

30 septembre 2026

Première publication (Réel)

6 octobre 2026

Mises à jour des dossiers d'étude

Dernière mise à jour publiée (Réel)

6 octobre 2026

Dernière mise à jour soumise répondant aux critères de contrôle qualité

30 septembre 2026

Dernière vérification

1 septembre 2026

Plus d'information

Termes liés à cette étude

Autres numéros d'identification d'étude

  • FSM-ORİ-ANGİO-2026
  • 2026/09-80 (Autre identifiant: University of Health Sciences Fatih Sultan Mehmet Training and Research Hospital Scientific Research Ethics Committee)

Informations sur les médicaments et les dispositifs, documents d'étude

Étudie un produit pharmaceutique réglementé par la FDA américaine

Non

Étudie un produit d'appareil réglementé par la FDA américaine

Non

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