Incidence and Location of Atelectasis Developed During Bronchoscopy Under General Anesthesia: The I-LOCATE Trial.

Background: Despite the many advances in peripheral bronchoscopy, its diagnostic yield remains suboptimal. With the use of cone-beam CT imaging we have found atelectasis mimicking lung tumors or obscuring them when using radial-probe endobronchial ultrasound (RP-EBUS), but its incidence remains unknown.

Research Question: What are the incidence, anatomic location, and risk factors for developing atelectasis during bronchoscopy under general anesthesia?

Study Design And Methods: We performed a prospective observational study in which patients undergoing peripheral bronchoscopy under general anesthesia were subject to an atelectasis survey carried out by RP-EBUS under fluoroscopic guidance. The following dependent segments were evaluated: right bronchus 2 (RB2), RB6, RB9, and RB10; and left bronchus 2 (LB2), LB6, LB9, and LB10. Images were categorized either as aerated lung ("snowstorm" pattern) or as having a nonaerated/atelectatic pattern. Categorization was performed by three independent readers.

Results: Fifty-seven patients were enrolled. The overall intraclass correlation agreement among readers was 0.82 (95% CI, 0.71-0.89). Median time from anesthesia induction to atelectasis survey was 33 min (range, 3-94 min). Fifty-one patients (89%; 95% CI, 78%-96%) had atelectasis in at least one of the eight evaluated segments, 45 patients (79%) had atelectasis in at least three, 41 patients (72%) had atelectasis in at least four, 33 patients (58%) had atelectasis in at least five, and 18 patients (32%) had atelectasis in at least six segments. Right and left B6, B9, and B10 segments showed atelectasis in > 50% of patients. BMI and time to atelectasis survey were associated with increased odds of having more atelectatic segments (BMI: OR, 1.13 per unit change; 95% CI, 1.034-1.235; P = .007; time to survey: OR, 1.064 per minute; 95% CI, 1.025-1.105; P = .001).

Interpretation: The incidence of atelectasis developing during bronchoscopy under general anesthesia in dependent lung zones is high, and the number of atelectatic segments is greater with higher BMI and with longer time under anesthesia.

Clinical Trial Registration: ClinicalTrials.gov; No.: NCT03523689; URL: www.clinicaltrials.gov.