DECLINE this machine! The Luna G3 BiPAP does not have a backup rate. It is a discount Chinese fabricated bilevel with CPAP, Bilevel-S and Auto bilevel. It does not have the required ST therapy mode and its performance matches the clunky appearance you already noted. Since this device does not meet the prescription, you should be entitled to return it.
I'm going to suggest the Aircurve 10 ST is also not an ideal machine, but will work better than the VPAP-S due to the backup rate. There are a couple of options we can discuss. The VPAP-ST provides fixed inhale and exhale (IPAP/EPAP) pressure. There is no intelligence in the machine, and it is suited for individuals with good spontaneous breathing that need breath augmentation and pacing provided by the ST, however it is poorly suited to treat central apnea. Two alternatives should be considered, and I have no idea how your doctor figures things out, but doing an in-clinic titration test would seem prudent for prescribing an appropriate device and pressures for a pediatric patient.
The Resmed Aircurve 10 ASV (Adaptive Servo Ventilation), protects the patient's minute vent with adaptive pressure support. That means the IPAP pressure changes to increase respiratory volume as needed, and when needed. The normal operation is similar to the Aircurve 10 VPAP-S with a minimum EPAP and pressure support, but the pressure support can increase on a breath by breath basis to even treat central apnea. If the patient does not spontaneously initiate a breath, the ASV will increase pressure to cause a breath, and once the normal lung volume is achieved, it reduces pressure back to EPAP. Many of our members use this device to treat central and complex sleep apnea. The Resmed ASV does not have a settable ventilation target rate, and uses the patient's minute vent and respiration rate from the preceding 90 seconds as the target volume and rate. This is a problem in some hypoventilation patients because the target vent rate can become progressively lower, and that may be contraindicated for your son.
The Resmed Aircurve 10 iVAPS is an intelligent form of the ST therapy and includes an ST mode as well as iVAPS (intelligent volume assured pressure support). The iVAPS mose works similarly to ASV, but is more targeted to pulmonary and thoracic diseases that include hypoventilation and forms of central apnea as well as COPD and more severe disease related issues. It is a ventilator that can target alveolar ventilation and maintain that target through the entire night. We have had members that require full ventilation support use this machine.
Please read this Resmed Sleep Lab Titration Guide with a focus on understanding the recommended uses for ST, iVAPS and ASV. This will help you to understand how each machine works, and the conditions each device is intended to treat. Once again, do not accept the 3B Medical G3 Luna!
https://document.resmed.com/en-us/docume...er_eng.pdf
As an after-thought, if we could look at some data from the VPAP-S we might be able to suggest some modifications that would make that machine more successful. It has a number of functions, most clinicians are unaware of that can help encourage spontaneous breathing and reduce central apnea. It is clearly not intended for therapy of central apnea, but it would be interesting to analyze the issues your son had with this.