An observational study in Postoperative Atelectasis, sponsored by Istanbul University - Cerrahpasa. Completed at 1 site in Turkey (Türkiye). Open to participants aged 18 Years to 80 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-07-06.
Sponsored by Istanbul University - Cerrahpasa · Observational
Atelectasis frequently develops during and after general anesthesia due to factors such as anesthesia-induced diaphragmatic dysfunction, reduced functional residual capacity, altered ventilation-perfusion matching, and surgical positioning. The development of atelectasis has been associated with postoperative hypoxemia and other pulmonary complications.
Lung ultrasound (LUS) has emerged as a reliable, radiation-free bedside imaging modality for the detection and monitoring of atelectasis. LUS allows assessment of lung aeration through standardized ultrasound patterns and scoring systems, enabling dynamic evaluation in the perioperative period.
This is a prospective, observational cohort study designed to compare the incidence and severity of atelectasis in patients undergoing surgery in the supine position versus the prone position under general anesthesia. Adult patients undergoing elective surgical procedures will be enrolled. No experimental intervention will be applied, and all anesthetic and surgical management will follow routine clinical practice.
Lung ultrasound examinations will be performed at predefined time points after induction of anesthesia and before extubation. A standardized lung ultrasound protocol and scoring system will be used to assess lung aeration loss and detect the presence of atelectasis.
The primary outcome of the study is the difference in atelectasis detected by lung ultrasound between supine and prone surgical positions. The secondary outcome is the change in lung ultrasound scores over time.
This study aims to clarify the effects of supine and prone positions on perioperative atelectasis and to support the clinical use of lung ultrasound as a noninvasive monitoring tool in perioperative and anesthetic practice..
301 studies on the registry are indexed under Pulmonary Atelectasis; 80 are open to participants now.
This study's enrollment of 80 is above the median of 72 across 73 observational studies indexed under Pulmonary Atelectasis.
Browse Pulmonary Atelectasis studies →Istanbul University - Cerrahpasa is the lead sponsor of 680 studies on the registry; 208 are open to participants now.
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The study population consists of adult patients aged 18 years and older who are scheduled to undergo elective surgical procedures under general anesthesia. Patients will be evaluated according to surgical positioning (supine or prone) during routine perioperative care.
Exclusion Criteria:
Patients undergoing surgery in the supine position under general anesthesia.
Patients undergoing surgery in the prone position under general anesthesia.
Difference in lung ultrasound-detected atelectasis between supine and prone surgical positions
Lung aeration will be evaluated using the Lung Ultrasound Score (LUS), a semiquantitative scoring system assessing aeration loss in 12 lung regions. In the supine position, lung ultrasound assessment will be performed along: the parasternal line (intercostal spaces 1-4 and 4-8), the anterior axillary line (intercostal spaces 1-6 and 6-12), and the posterior axillary line (intercostal spaces 1-6 and 6-12). In the prone position, lung ultrasound assessment will be performed along: the paravertebral line (intercostal spaces 1-6 and 6-12), the posterior axillary line (intercostal spaces 1-6 and 6-12), and the anterior axillary line (intercostal spaces 1-6 and 6-12). Each lung region will be scored from 0 to 3, resulting in a total LUS ranging from 0 to 36, where higher scores indicate greater loss of aeration and more severe atelectasis. Assessments will be performed after induction of general anesthesia and before extubation.
Time frame: Perioperative (After induction of general anesthesia and before extubation)
Plan to share: No — Individual participant data will not be shared, as this is a single-center observational study conducted for a postgraduate thesis.
This study is completed, as verified in Mar 2026. You cannot join it, but the record below documents what was studied.
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Istanbul University - Cerrahpasa