Atelectasis, Hyperoxia, Lung Ultrasonography Score
Conditions
Keywords
Atelectasis, ORI, robotic surgery, lung ultrasound score, hyperoxia
Brief summary
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.
Detailed description
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.
Interventions
PROCEDUREPeripheral Oxygen Saturation (SpO₂) Group
FiO₂ adjusted based on pulse oximetry to maintain SpO₂ ≥98%
PROCEDUREPeripheral Oxygen Saturation and Oxygen Reserve Index (SpO₂-ORI) Group
FiO₂ adjusted using both SpO₂ and ORI to maintain ORI between 0-0.3
Sponsors
Antalya Training and Research Hospital
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
TRIPLE (Subject, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
18 Years to 75 Years
Healthy volunteers
No
Inclusion criteria
* American Society of Anesthesiologists Physical Status Classification System (ASA) physical status I-III * Elective robotic surgery under general anesthesia * Surgery duration \>2 hours * Requires invasive arterial cannulation * Signed informed consent
Exclusion criteria
* ASA IV or higher * Room air SpO₂ \<92% * Chronic pulmonary disease * Hemoglobinopathy * Pregnancy * Refusal to participate
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Postoperative LUS score at 30 min | At 30 minutes following tracheal extubation at the end of surgery | 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 |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Preoperative LUS score | 30 minutes prior to patient transfer to the operating room | 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 |
| Intraoperative arterial partial pressure of oxygen (PaO₂) | At baseline (immediately before incision), and at 1st, 2nd, and 3rd hour intraoperatively | 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). |
| Intraoperative fraction of inspired oxygen (FiO₂) | At baseline (immediately before incision), and at 1st, 2nd, and 3rd hour intraoperatively | 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. |
| Intraoperative Oxygen Reserve Index (ORI) | At baseline (immediately before incision), and at 1st, 2nd, and 3rd hour intraoperatively | 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. |
| Number of episodes with severe hyperoxia (PaO₂ > 200 mmHg) | At baseline (immediately before incision), and at 1st, 2nd, and 3rd hour intraoperatively | 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. |
Countries
Turkey (Türkiye)
Outcome results
None listed