Purpose: We aimed to introduce a simple, lightweight continuous positive airway pressure (CPAP)-delivery device for the nondependent lung during one-lung ventilation, to investigate how the type of three-way stopcocks, and the compliance and resistance of a test lung affect the relationship between the oxygen flow rate and CPAP level produced, and to examine how the device works in a clinical setting.
Methods: In the test lung study, the bronchial blocker of a Univent tube was connected to a test lung. The effects of oxygen-flow rate, types of three-way stopcocks, and compliance and resistance of the test lung on the CPAP levels were studied. In the clinical study, the lightweight device was used to treat hypoxia in seven patients during one-lung ventilation with the bronchial blocker.
Results: In the test lung study, the CPAP level produced by the device was proportional to the oxygen-flow rate, dependent on the type of three-way stopcock used, and independent of the compliance or resistance of the test lung. There was no discrepancy between the plateau pressures of the test lung and the monitoring port of an additional stopcock at any degree of compliance or resistance of the test lung at any oxygen-flow rate. Therefore, the relationship between the oxygen-flow rate and CPAP level can be ensured in advance before application to the lung, with an additional three-way stopcock of which the distal end is occluded. In the clinical study, peripheral oxygen sataration Sp(O2) improved while the CPAP level ranged from 2.8 to 5.4 cmH2O.
Conclusion: The lightweight CPAP delivery-device can provide variable CPAP levels by adjusting the oxygen-flow rate without real-time monitoring of the pressure.