Severe COPD and blood pressure

Hi everyone, my mum has severe copd and palliative care at home. She has suffered extremely high blood pressure for many year, for the last week her systolic sitting on her usual of 160 above but diastolic has dropped down under 75, very unusual for mum. Should i be concerned about this?

She is on 24/7 oxygen which she drops under her required level on occasions nothing alarming. Mum has been in hospital on numerous occasions (i lost count).

Thanks in advance for any advice. 🤔🙂