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Updated: Aug 20, 2026

Investigation into Deep Breathing through Measurement of Ventilatory Parameters and Observation of Breathing Patterns
Published on: September 16, 2019
Influence of proportional assist ventilation on diaphragmatic activity in normal subjects
1Vivantes-Klinikum Neukölln, Klinik für Innere Medizin-Pneumologie und Infektiologie, Rudower Strasse 48, D-12351 Berlin, Germany. wulf.pankow@vivantes.de
Abstract:
In six awake healthy adults we studied the physiological effects of mechanical unloading of the respiratory muscles during increased ventilatory demand. We were interested in whether respiratory muscle activity is down regulated and if this is mainly a consequence of chemical factors, i.e. CO2-reduction, or non-chemical neuromuscular inhibition. With 33 mmHg inspiratory CO2 we induced modest hyperpnea of 24.4 +/- 3.9 L/min. Proportional assist ventilation (PAV) was applied with flow-related assist of 2.5 cm H2O/L/s and volume-related assist of 6 cm H2O/L. Respiratory muscle activity was measured by transdiaphragmatic pressure. Unloading caused a 57 percent reduction of the inspiratory transdiaphragmatic pressure-time product (p<0.05), while tidal volume, breathing frequency, and breathing pattern did not significantly change. These observations suggest that during increased ventilatory requirements, PAV results in down regulation of respiratory muscle activity and that this effect is mainly a consequence of neuromechanical inhibition.
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