Using the ASL 5000 Breathing Simulator as the basis of our method, we wanted to explore the question: how effective is the delivery of neonatal nasal CPAP through a variety of devices like the SiPAP, regular oxygen nasal prongs, and specialty prongs like the RAM cannula? The challenges we faced were: building a nasal simulation attachment for the ASL 5000, creating a spontaneously breathing neonatal model on the ASL 5000, and displaying the data so that we could comparatively study the results.
The first challenge was to make a representative neonatal nasal interface for the ASL 5000. Initially we modified several mannequin models where we had problems with leaks and attaching the prongs properly to the model. The best solution we tried is a simple plastic connector with precisely drilled holes to represent the neonatal nares. The advantages of this interface is that the size of the nares can be precisely controlled, we could test a variety of sized nares, and the different types of test prongs could be reliably attached to the ASL 5000.
Creating a neonatal spontaneously breathing model on the ASL 5000 is easily done but several unique questions arose such as: What is the lung / thoracic compliance of a preterm patient who is in respiratory distress due to lung disease? What would the inspiratory flow, Ti, or I:E ratio of such a patient would be? Even with all these unanswered questions we did eventually agree on a standard breathing model.
Our last challenge was the analysis of the data and here we were aided by the vast array of data and waveforms available from the ASL 5000 software. The difficulty for us was to retrieve the desired waveforms of pressure, volume, and flow for each of the different devices and reproduce them for comparative analysis. To make our desired graphic images we used the ASL 5000 “export” function to load the waveforms into Adobe Photoshop. In Photoshop the line colors and background were removed and the lines sharpened. The final assembly of the images required that they be sized to an exact scale and for this we used Microsoft PowerPoint. Within PowerPoint, a background grid was created and then the images were overlaid and manipulated by being stretched/expanded to fit the required scale.
The results justified our efforts as the data created on the ASL 5000 is reproducible, our nasal adaptor works well, and can we can demonstrate our data effectively. From this study we can confidently demonstrate the subtle differences of nasal CPAP delivered through the different devices commonly used in our NICUs under simulated spontaneous breathing conditions.
Now we face the last monumental challenge of writing up the study and possibly submitting it for publication.