Hello dear, thanks for your question on HCM. I can understand your situation and problem. RSV (respiratory syncytial virus) infection in asthmatic patients is very dangerous and causing severe bronchospasm with super added bacterial infection. Both these conditions cause poor oxygenation of lungs. This ventilation perfusion mismatch occur. So deoxygenated blood will not be properly oxygenated. And this causes low oxygenation.