Presenting Author Scarsdale High School Scarsdale, New York
Chronic obstructive pulmonary disease (COPD) is a common lung disease characterized by limited expiratory airflow due to lung destruction or airway obstruction. Chest wall strapping (CWS) is a potential therapy technique that restricts the upper abdomen, inducing breathing at lower lung volumes and opening small airways. Although the respiratory impacts of CWS have been examined, the relationship between CWS and the cardiovascular system, which is closely tied to ventilation, has not been well-established. Additionally, COPD patients have reduced autonomic nervous system activity, which may be reflected in cardiorespiratory coupling. Cardiorespiratory coupling causes increased heart rate during inhalation to accommodate for increased blood return. The strength of this relationship was evaluated during CWS in five COPD and six control patients by analyzing heart rate changes during ventilation cycles. Heart rate and ventilatory data were collected during baseline, CWS, and post-CWS removal periods. Average heart rate during each inhalation and exhalation was plotted against tidal volume, with the slope of the linear regression representing the strength of the cardiorespiratory coupling relationship (BPM/L). Multi-factor ANOVA statistics showed a significantly diminished strength in COPD patients compared to control (p lt; 0.001). There was no significant change in either group post-CWS, suggesting that the same-sized breaths will cause the heart to respond similarly regardless of the total lung capacity. A potential consequence of diminished cardiorespiratory coupling in COPD patients is strain on the right side of the heart, which then has to pump larger stroke volumes. Blunted cardiorespiratory coupling is not further impaired by CWS.
Sample patient derivations for reflex strength. Linear regressions to derive slope (reflex strength), were performed in Excel. Each point represents the average heart rate during an inhalation or exhalation breath, with negative tidal volume representing inhalations and positive representing exhalations.; COPD and control reflex slopes. Slopes for control and COPD participants plotted as a function of time with time points for baseline, CWS, and post-CWS conditions. The slope equals the change in heart rate per change in volume (BPM/L). A more negative slope (heart rate/tidal volume) represents a stronger reflex. Data points and error bars reflect the average reflex slopes for the control and COPD groups.
