Contraindications
Positive airway pressure therapy may be contraindicated in some patients with the following pre-existing conditions:
- severe bullous lung disease 
- pneumothorax or pneumomediastinum 
- pathologically low blood pressure, particularly if associated with intravascular volume depletion 
- dehydration 
- cerebrospinal fluid leak, recent cranial surgery, or trauma. 
ASV therapy is contraindicated in patients with chronic, symptomatic heart failure (NYHA 2-4) with reduced left ventricular ejection fraction (LVEF ≤ 45%) and moderate to severe predominant central sleep apnea.