An interventional study of Peripheral Oxygen Saturation (SpO₂) Group and Peripheral Oxygen Saturation and Oxygen Reserve Index (SpO₂-ORI) Group in Atelectasis, Lung Ultrasonography Score and Hyperoxia, sponsored by Antalya Training and Research Hospital. Completed at 1 site in Turkey (Türkiye). Open to participants aged 18 Years to 75 Years. Per ClinicalTrials.gov, last updated 2025-12-10.
Sponsored by Antalya Training and Research Hospital · Not applicable, Interventional, and Prevention
This single-center randomized controlled trial aims to evaluate whether intraoperative monitoring using the Oxygen Reserve Index (ORI) reduces the incidence of postoperative atelectasis, as assessed by lung ultrasound (LUS), in adult patients undergoing elective robotic surgery under general anesthesia.
Postoperative atelectasis is observed in 60-90% of patients undergoing general anesthesia. Factors such as high inspired oxygen concentration, muscle relaxation, and reduced functional residual capacity contribute to its development through mechanisms like absorption atelectasis. The persistence of atelectasis increases the risk of pneumonia, hypoxia, prolonged hospital stay, healthcare costs, and mortality. Despite the well-known pathophysiology, the optimal intraoperative fraction of inspired oxygen (FiO₂) remains unclear.
The Oxygen Reserve Index (ORI) is a non-invasive, continuous parameter that reflects the oxygen reserve within the moderate hyperoxia range (100-200 mmHg). It may facilitate individualized FiO₂ titration to avoid hyperoxia-related atelectasis. Lung ultrasound (LUS) is a reliable, radiation-free bedside tool for detecting atelectasis.
This study hypothesizes that ORI-guided oxygen therapy will reduce the incidence of postoperative atelectasis compared to standard Peripheral Capillary Oxygen Saturation (SpO₂)-guided therapy.
377 studies on the registry are indexed under Pulmonary Atelectasis; 93 are open to participants now.
This study's enrollment of 58 is close to the median of 60 across 268 interventional studies indexed under Pulmonary Atelectasis.
Browse Pulmonary Atelectasis studies →Antalya Training and Research Hospital is the lead sponsor of 104 studies on the registry; 12 are open to participants now.
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Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The anaesthetists’ scale of health before surgery: I is healthy, II has a mild illness that is under control, III a severe one, IV a severe illness that is a constant threat to life. V and VI are used for the critically ill and for organ donors.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
ASA physical status
The anaesthetists’ scale of health before surgery: I is healthy, II has a mild illness that is under control, III a severe one, IV a severe illness that is a constant threat to life. V and VI are used for the critically ill and for organ donors.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
FiO₂ adjusted based on pulse oximetry to maintain SpO₂ ≥98%
Procedure: Peripheral Oxygen Saturation (SpO₂) Group
FiO₂ adjusted using both SpO₂ and ORI to maintain ORI between 0-0.3
Procedure: Peripheral Oxygen Saturation and Oxygen Reserve Index (SpO₂-ORI) Group
FiO₂ adjusted based on pulse oximetry to maintain SpO₂ ≥98%
FiO₂ adjusted using both SpO₂ and ORI to maintain ORI between 0-0.3
Postoperative LUS score at 30 min
Lung ultrasound (LUS) measurements will be performed by an anesthesiologist blinded to the study groups, who is experienced in lung ultrasonography with at least 100 prior examinations. LUS will be performed and recorded 30 minutes before surgery while patients are in the supine position, using a linear probe (6-12 MHz). The total LUS score will be calculated as the sum of the scores for the 12 quadrants of each hemithorax (range: 0-36). Higher scores will indicate more severe loss of aeration. Loss of aeration will be scored as follows: * 0: Presence of A-lines or fewer than two B-lines * 1: Three or more well-defined B-lines * 2: Presence of multiple coalescent B-lines * 3: Presence of lung consolidation characterized by dynamic air bronchograms
Time frame: At 30 minutes following tracheal extubation at the end of surgery
Preoperative LUS score
Lung ultrasound (LUS) measurements will be performed by an anesthesiologist blinded to the study groups, who is experienced in lung ultrasonography with at least 100 prior examinations. LUS will be performed and recorded 30 minutes before surgery while patients are in the supine position, using a linear probe (6-12 MHz). The total LUS score will be calculated as the sum of the scores for the 12 quadrants of each hemithorax (range: 0-36). Higher scores will indicate more severe loss of aeration. Loss of aeration will be scored as follows: • 0: Presence of A-lines or fewer than two B-lines • 1: Three or more well-defined B-lines • 2: Presence of multiple coalescent B-lines • 3: Presence of lung consolidation characterized by dynamic air bronchograms
Time frame: 30 minutes prior to patient transfer to the operating room
Intraoperative arterial partial pressure of oxygen (PaO₂)
Arterial blood samples will be collected intraoperatively at baseline (immediately before skin incision) and at the 1st, 2nd, and 3rd hour to measure the partial pressure of oxygen (PaO₂).
Time frame: At baseline (immediately before incision), and at 1st, 2nd, and 3rd hour intraoperatively
Intraoperative fraction of inspired oxygen (FiO₂)
The fraction of inspired oxygen administered to the patient will be recorded at baseline (immediately before skin incision) and hourly at the 1st, 2nd, and 3rd hour during surgery.
Time frame: At baseline (immediately before incision), and at 1st, 2nd, and 3rd hour intraoperatively
Intraoperative Oxygen Reserve Index (ORI)
Continuous monitoring of the Oxygen Reserve Index (ORI) will be performed, and values will be documented at baseline (immediately before skin incision) and at 1st, 2nd, and 3rd hour intraoperatively.Intraoperative Oxygen Reserve Index (ORI) will be measured. ORI is a unitless index ranging from 0.00 to 1.00, with higher values indicating a greater oxygen reserve.
Time frame: At baseline (immediately before incision), and at 1st, 2nd, and 3rd hour intraoperatively
Number of episodes with severe hyperoxia (PaO₂ > 200 mmHg)
The number of severe hyperoxia episodes, defined as PaO₂ levels exceeding 200 mmHg, will be recorded at baseline (immediately before skin incision) and at the 1st, 2nd, and 3rd hour during surgery.Each time point will be evaluated independently, and the number of measurements exceeding 200 mmHg will be counted.This is a binary threshold-based event count, not a continuous scale; thus, no scoring system or scale interpretation is applicable.
Time frame: At baseline (immediately before incision), and at 1st, 2nd, and 3rd hour intraoperatively
This study is completed, as verified in Dec 2025. You cannot join it, but the record below documents what was studied.
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