Gasping? OSA? If you are asking why you're still gasping for air even with your CPAP or bipap, then either you need an adjustments to your settings or there are other factors than obstructive sleep apnea (osa) occurring that your provider needs to address or explain.
Something is up. Gasping suggests central apnea, medicine effects, or pulmonary disease. Many meds can cause respiratory suppression including opiates, benzodiazepines, antidepressants esp ssri's, and any medicine for that matter - best defined by the chronology of its introduction and the onset of symptoms. The set on CPAP could be off and as well consider anxiety as a potential cause.