Lung lobes most commonly affected by Aspiration (Upright vs. Supine)

Aspiration events have a gravity-based predilection, meaning the lobes/ lung segments in the most dependent positions are likely affected. Also, the right main bronchus has a larger luminal diameter and more vertical trajectory than the left main bronchus making it more susceptible to aspirated content.

Lobes of the lungs most likely to be affected by aspiration include:

Upright: The lower lobes (Right>Left)

Supine: Superior segments of the lower lobes (Right>Left) or posterior segment of the RIGHT upper lobe. This is typically in patients with altered LoC (i.e Alcoholics, Intubated patients etc.).  

REFERENCES:

1. Kuhajda, Ivan et al. “Lung Abscess-Etiology, Diagnostic and Treatment Options.” Annals of Translational Medicine 3.13 (2015): 183. PMC. Web. 14 Sept. 2018.
2. Kim M, Lee KY, Lee KW et-al. MDCT evaluation of foreign bodies and liquid aspiration pneumonia in adults. AJR Am J Roentgenol. 2008;190 (4): 907-15.
3. Moreira Jda S, Camargo Jde J, Felicetti JC, et al. Lung abscess: analysis of 252 consecutive cases diagnosed between 1968 and 2004. J Bras Pneumol 2006;32:136-43.