Atelectasis in Obese Patients Undergoing Bariatric Surgery

Pulmonary atelectasis is commonly present in obese patients even before surgery. 

The goal of a cross-sectional was to assess the prevalence and extent of preoperative atelectasis in obese individuals undergoing bariatric surgery and to determine if variations in preoperative oxygen saturation (Spo2) at room air in the seated position are linked to the extent of atelectasis seen in the supine position.

This study was undertaken at a bariatric surgery center––preoperative chest CT scans were reviewed to measure atelectasis as a percentage of total lung volume. Atelectasis was defined as ≥2.5% lung volume. 

The study included 236 patients with a median BMI of 40.3 kg/m² (range 30.0–77.3 kg/m²). The overall prevalence of atelectasis was 32.6%. Prevalence rates varied by BMI category – 30 to 35 kg/m² had 12.7%; 35 to 40 kg/m² had 28.3%; 40 to 45 kg/m² had 12.3%; 45 to 50 kg/m² had 48.4%; and ≥50 kg/m² had 100%. Higher BMI categories (≥45 kg/m²) showed significantly greater atelectasis prevalence and percentage coverage than those with lower BMI. Specifically, BMI ≥45 kg/m² had an adjusted prevalence ratio of 3.52 to 8.0 and an adjusted odds ratio of 7.5 to 91.5 for increased atelectasis coverage. Atelectasis accounted for 70.2% of the variation in preoperative Spo2, with 81.5% of the effect of BMI on Spo2 <96% mediated through atelectasis.

From the results, it was inferred that preoperative atelectasis is prevalent in obese patients undergoing bariatric surgery, especially in those with a BMI ≥45 kg/m². This atelectasis significantly impacts preoperative Spo2 levels and should be considered when planning perioperative care and interpreting postoperative outcomes.

Source: Mancilla-Galindo J, Ortiz-Gomez JE, Pérez-Nieto OR, et al. Anesthesia & Analgesia. 2022 Mar 18:10-213.