Related Experiment Video
Updated: Aug 26, 2026

Measurement of the Pressure-volume Curve in Mouse Lungs
Published on: January 27, 2015
The effect on expiratory flow rate of maintaining bag compression during manual hyperinflation
Lyndal J Maxwell1, Elizabeth R Ellis
1University of Sydney, Lidcombe, NSW, 2141, Australia. L.Maxwell@fhs.usyd.edu.au
Abstract:
Operator performance during the expiratory phase of manual hyperinflation appears to vary between physiotherapists for Mapleson-B or C circuits. Some physiotherapists release the valve but maintain compression of the bag, whereas others release both the valve and the bag. The effect of this difference on peak expiratory flow rate (PEFR) has not been reported. The aim of this study was to document the effect of maintaining bag compression during expiration on PEFR and inspiratory to expiratory flow rate ratio (I:E). Six physiotherapists with experience using manual hyperinflation participated. A within-subjects repeated measures design was used. Subjects performed manual hyperinflation using a Mapleson-C circuit with 'rapid release', releasing the valve only, or releasing both the bag and the valve, during expiration in a test lung model. Inspiratory time was controlled using a metronome and flows were measured with a heated pneumotachometer. Maintaining bag compression significantly reduced PEFR (1.54 (0.08) vs 2.00 (0.07) l/sec, p = 0.008) and increased I:E flow rate ratio (0.65 (0.04) vs 0.50 (0.02), p = 0.02) for the Mapleson-C circuit at a 1.4 litre target volume. There were no significant differences for these measures between techniques when subjects emptied the bag. The effect needs to be confirmed in the clinical setting.
Related Concept Videos
Pulmonary Cycle: Exhalation
Atelectasis II: Pathophysiology
Pulmonary Ventilation: Inhalation
Boyle's law becomes particularly pertinent when examining respiratory...
Hyperpnea and Hyperventilation
Related Rates
Pressure Relationships in Thoracic Cavity
Breathing Mechanisms
Both intra-alveolar and intrapleural pressures rely on specific lung properties. The ability to breathe—allowing air to enter the lungs during...