A comparison of expiratory flow rates in two breathing circuits used for manual inflation of the lungs

Abstract

Manual inflation of the lungs by the 'bag squeezing method' (bagging) is commonly used by physiotherapists in the management of intubated patients. A wide variety of 'bagging' circuits are available and the peak expiratory flow rate that can be achieved is influenced by the circuit components. A high expiratory flow rate is desirable as it is believed to be one of the factors that determines the effectiveness of secretion mobilisation during a simulated cough in intubated patients. This study was designed to compare the expiratory flow rates resulting from the elastic recoil of a test-lung using the Mapleson-C breathing system and the Laerdal self-inflating resuscitator. Our data demonstrated that for any given pressure gradient the measured peak expiratory flow was higher with the Laerdal self-inflating resuscitator (p < 0.001). Further studies are required to assess the influence of circuit-type pulmonary secretion mobilisation in clinical practice.