An EIT-based assessment of regional ventilation delay under incremental PEEP: Influence of sex, smoking, vaping, asthma, and BMI

Abstract

Background and Objective

Therapies such as positive airway pressure (PAP), which maintain positive end-expiratory pressure (PEEP) settings, are widely used in the management of respiratory diseases. However, most research has focused on patient outcomes, such as oxygenation, mortality rates, or ventilator-free days. There is a lack of focus on lung-specific responses, for example, atelectasis rate or aeration heterogeneities. This study aims to use Electrical Impedance Tomography (EIT) to investigate variations in lung aeration heterogeneity with increasing PEEP and how factors such as sex, smoking/vaping history, asthma, and BMI influence lung aeration dynamics.

Methods

Eighty participants were recruited and categorized into four groups: asthmatics, smokers, vapers, and healthy individuals. Each group comprises 20 subjects evenly distributed by sex (10 females and 10 males). Varying PEEP was applied on each subject during the trial, which began at zero end-expiratory pressure (ZEEP) and subsequently increased from 4 to 12 cmH₂O on non-invasive ventilation (NIV). EIT data were collected at each pressure level. Lung aeration heterogeneity was assessed using regional ventilation delay (RVD), a promising metric derived from EIT data for evaluating lung-specific responses to mechanical ventilation. RVD and its standard deviation (SDRVD) of each subject were calculated accordingly at ZEEP and the highest PEEP level.

Results

Results demonstrated that female participants exhibited a significant increase in RVD when pressure was elevated from ZEEP to higher levels, whereas male participants showed no such significant change. Overweight subjects experienced no significant alterations in RVD under highest PEEP, whereas non-overweight subjects showed significantly increased RVD under higher pressure levels. Vaping was associated with a statistically significant increase in RVD when pressure was at the highest PEEP level, whereas no significant RVD changes were observed among smokers or subjects with mild asthma within this relatively young population.

Conclusions

These findings emphasize the importance of considering individualized factors when optimizing respiratory therapy, including sex and BMI. These factors significantly influence regional lung aeration and ventilation dynamics, and play important roles in optimising mechanical ventilation settings, which could potentially enhance therapeutic effectiveness and patient outcomes.