New research using electrical impedance tomography (EIT) shows that lateral, prone, and sitting positions significantly redistribute airflow in the lungs compared to supine position.
RT’s Three Key Takeaways:
- Lateral Positioning Impact: Lateral decubitus positions produce the most significant gravity-dependent shifts in ventilation, with the effect appearing more asymmetric when participants lie on their right side.
- Influencing Factors: Body mass index, cardiothoracic ratio, and diaphragmatic movement are associated with how ventilation redistributes when gravitational loading changes.
- Clinical Monitoring: Electrical impedance tomography (EIT) provides a sensitive, real-time method for quantifying how different postures affect regional respiratory physiology compared to a supine baseline.
Body position reshapes ventilation distribution in healthy lungs, with lateral positioning producing the strongest gravity-dependent shifts, according to a study published in Respiratory Physiology & Neurobiology.
Researchers used electrical impedance tomography (EIT) to examine how regional ventilation changed across five body positions in 10 healthy male volunteers. EIT is a noninvasive, radiation-free technique that continuously measures breathing-related changes in thoracic impedance, allowing investigators to assess regional ventilation in real time.
The study compared within-person changes relative to the supine position while participants were prone, sitting, and lying in right and left lateral decubitus positions. Lateral positioning produced the clearest ventilation redistribution, with airflow shifting toward the dependent lung regions and away from the nondependent regions.
While overall dorsoventral ventilation patterns appeared broadly similar between the supine, prone, and sitting positions, an analysis identified smaller but statistically significant shifts during prone positioning and sitting when compared to the supine baseline. The findings indicate that proportional ventilation measurements alone may overlook subtle redistribution, and measuring within-person changes against a common baseline may provide a more sensitive method for characterizing position-related respiratory physiology.
The researchers also investigated factors explaining individual variations in ventilation distribution. Redistribution during lateral positioning was associated with body mass index (BMI) and cardiothoracic ratio, suggesting that body composition and thoracic morphology may influence the effect of gravity on the lungs. Changes during sitting were associated with diaphragmatic excursion, indicating that diaphragm movement contributes to ventilation redistribution.
These exploratory findings establish a physiological framework for quantifying how posture affects regional ventilation, which could support future research into positioning strategies, respiratory rehabilitation, and ventilation monitoring in people with respiratory disease or those receiving mechanical ventilation.
However, the study included only 10 healthy male volunteers with a relatively narrow BMI range. The results may not be generalizable to women, older adults, or people with cardiopulmonary disease, and larger studies are required before the findings can guide clinical positioning decisions.
Reference
Tsuji H et al. Posture-related ventilation redistribution and associated factors in healthy subjects assessed by electrical impedance tomography. Respir Physiol Neurobiol. 2026;doi:10.1016/j.resp.2026.104619. https://www.sciencedirect.com/science/article/abs/pii/S1569904826000789?via%3Dihub
This article was originally published by AMJ and was made available under the terms of the Creative Commons Attribution-Non Commercial 4.0 License.
