The effect of proportional assist ventilation on diaphragm electrical activity

The diaphragm is the largest contributing muscle in a spontaneous breath. Classically, when failure in this muscle occurs, mechanical ventilation is implemented to reduce acute respiratory failure. The proportional assist ventilator (PAV) is a type of mechanical ventilator that can maintain gas homeostasis in dynamic exercise. However, PAV’s effect on the diaphragm, accessory respiratory muscles, and effectiveness during lower intensity exercise is still unclear. PURPOSE: To investigate the diaphragm electrical activity during low exercise intensity (10% below gas exchange threshold (GET)) while reducing the work of breathing via a PAV. METHODS: 8 participants (n = 4 male, n = 4 female; 26.8 ± 1 years) completed two days of testing. On day one, subjects performed a maximal VO2 exercise test on a cycle ergometer. On day 2, subjects cycled at 10% below GET while alternating breathing on the PAV and spontaneously. Electromyography of the diaphragm (EMGdi), scalenes (EMGSCA), and sternocleidomastoids (EMGSCM), work of breathing (WOB), pressure time product of the esophagus (PTPes), diaphragm (PTPdi) and gastric (PTPga) were measured throughout the experimental protocol. RESULTS: WOB was lower while breathing on the PAV during medium (p < 0.05) and high (p < 0.01) unloading conditions. PTPes was significantly lower while breathing on the PAV for low, medium, and high unloading assistance (p < 0.05; p < 0.01; p < 0.01) compared to spontaneous breathing. PTPdi was significantly lower while breathing on the PAV for low, medium, and high comparisons (p < 0.05, p < 0.01; p < 0.01) compared to spontaneous breathing. While PTPgas was significantly lower when breathing on the PAV during high levels of unloading (p < 0.01) compared to spontaneous breathing. EMGdi was lowered while breathing during all PAV unloading levels (low, medium, and high) compared to spontaneous breathing (p < 0.05; p < 0.05; p < 0.05). EMGSCA was reduced when breathing on the PAV during high unloading versus spontaneous breathing (p < 0.05). EMGSCM showed no reductions between PAV unloading levels and spontaneous breathing. CONCLUSION: PAV reduces WOB during exercise below 50% of VO2MAX and simultaneously reduces the diaphragm electrical activity.Education, Faculty ofKinesiology, School ofGraduat