Abstract

Background: Positive end-expiratory pressure (PEEP) influences respiratory mechanics, ventilation distribution, and lung aeration. However, comparative responses to incremental PEEP among healthy individuals, cigarette smokers, electronic cigarette users, and individuals with asthma remain poorly understood. This study aimed to characterize differential respiratory responses to incremental PEEP across these populations. Methods: A secondary analysis was conducted using an open-access respiratory physiology dataset obtained from PhysioNet. Eighty adults were included and categorized into four groups (n = 20 per group): healthy controls, cigarette smokers, electronic cigarette users, and individuals with asthma. Airway pressure, respiratory flow, tidal volume, chest circumference, abdominal circumference, and global aeration were evaluated across incremental PEEP levels ranging from 4 to 12 cmH2O. Results: Increasing PEEP significantly affected all respiratory and aeration outcomes (all p < 0.001). Significant Group × PEEP interactions were observed for airway pressure (p < 0.001), respiratory flow (p = 0.009), chest circumference (p = 0.002), and abdominal circumference (p = 0.005), indicating differential physiological responses among groups. In contrast, tidal volume (p = 0.067) and global aeration (p = 0.170) demonstrated similar response patterns across groups despite significant overall PEEP effects. Conclusions: Incremental PEEP significantly influenced respiratory mechanics, thoracoabdominal motion, and lung aeration. Respiratory responses differed among healthy controls, cigarette smokers, electronic cigarette users, and individuals with asthma, suggesting group-specific adaptations to increasing PEEP.

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