Breathing pattern and its variability in young individuals with obesity.

Changes in breathing pattern and breathing pattern variability have been associated with a wide spectrum of pathological states. Obesity is associated with changed mechanical properties of the chest potentially influencing breathing pattern. However, there is only limited information on changes in the breathing pattern in young individuals with obesity and the variability of the breathing pattern has not yet been investigated. Therefore, the aim of this study was to assess the breathing pattern changes in young individuals with obesity, focusing on its variability. We investigated 47 patients with obesity and 47 sex and age matched control subjects, mean age 17.6 years. Tidal volume and duration of inspiration and expiration were breath-to-breath recorded using respiratory inductive plethysmography method during five consecutive phases. Further we calculated following parameters: respiratory cycle duration (Ttot), respiratory rate (fR), minute ventilation (MV), the duty cycle (Ti/Ttot), mean inspiratory flow (Vt/Ti) and a measure of rapid shallow breathing (fR/Vt). Mean values of all respiratory parameters were used as representative values for the given phase and their variability was quantified using standard deviation (SD) and coefficient of variation (CV). Patients with obesity were characterized by reduced Vt and increased fR mostly at rest and by a decreased expiration duration resulting in an increase in Ti/Ttot ratio. While Vt/Ti did not differ between two groups, fR/Vt ratio was significantly increased in the obese group. Concerning respiratory variability, we found an increased variability of several respiratory parameters (respiratory rate, minute ventilation, inspiratory flow, Ti/Ttot ratio, fR/Vt ratio) in patients with obesity mostly at rest. We conclude that initial changes in breathing pattern and breathing pattern variability are already present in young patients with obesity. These changes could serve as a potential marker to distinguish patients with increased risk of developing obesity related respiratory complications.