Variables associated with the use of bubble continuous positive airway pressure (bCPAP)

Variables associated with the use of bubble continuous positive airway pressure (bCPAP): Evaluation through testing and simulation integration

Janssen, Luc (TU Delft Mechanical, Maritime and Materials Engineering)

Dankelman, J. (mentor)

Delft University of Technology

Mechanical Engineering | BioMechanical Design

2021-12-14

Background:
The leading cause of the death of children under the age of 5 are complications associated with premature birth. A widely used ventilation modality is bubble continuous positive airway pressure (bCPAP),which is used predominantly for neonates and infants with respiratory distress. bCPAP makes use of a flow of air and oxygen from an oxygen concentrator which is administered to the patient via an interface. The expiratory tube is placed into a water bottle which acts as a pressure valve and regulates the pressure inside the system.
Aim: The aim of this research is to identify and investigate the variables that influence the performance of the bCPAP system.
Methods:
The equipment that is used and investigated are different types of interfaces and tubings as well as different sizes of interfaces. The relation between flow and pressure setting on the oxygen concentrator and pressure output at the interface is essential to this system. Other variables that are investigated include leak, airway resistance, lung compliance and respiratory rate. Four different evaluation methods are used; Solidworks flow simulation, standalone testing, lung simulator testing and Simulink simulation.
The Solidworks flow simulation investigates the flow patterns through the interfaces and tubing. The standalone testing determines the pressure output at the interface without a simulated patient attached. A lung simulator is used to determine the effects of a respiratory cycle on the bCPAP system. The Simulink simulation investigates the various physiological aspects of airway resistance and lung compliance as well as the simulation of leak.
Results: The variable with the largest impact on the performance of the bCPAP system is the type of interface that is used. The Hudson prongs show a large increase in Work of Breathing (WOB) compared to the RAM cannula. The bCPAP system is mostly flow independent during continuous bubbling although Hudson prongs are more flow dependent compared to the RAM cannula. The air flow through the RAM cannula is slightly different for inspiration and expiration due to the connectors used, at the connectors the largest pressure drop occurs.
The respiratory characteristics of potential patients are crucial to ensure an effective use of the bCPAP system. When leak is introduced the air delivery is decreased significantly and the possibility of not achieving continuous bubbling increases as well as the possibility of rebreathing of oxygen poor air. No clear differences are found in types of tubing or between the resistance of the two interface types. If the pressure in the water bottle is increased by 1 cm H2O, the output pressure at the interface is increased by 0.94 cm H2O on average.
Conclusion: The variable with the largest impact on the performance of the bCPAP system is the type of interface that is used. The performance of bCPAP is above all dependent on matching the physiological characteristics of the potential patient to the possibilities and properties presented by the bCPAP system.

http://resolver.tudelft.nl/uuid:66f47edc-5bd0-4d7a-8c58-1ef48364c779

2023-12-14

Student theses

master thesis

© 2021 Luc Janssen