Grandmother Lynn Hadley, 67, died in the blaze at her end-terrace house in New Street, Shelfield, at around 5pm on Easter Monday.
Black Country Coroners Court opened an inquest into her death on Thursday.
Paramedics were called to the house after Mrs Hadley had been displaying symptoms of coronavirus but, as crews started oxygen treatment, sparks from the device set fire to the armchair where Mrs Hadley was sat, the inquest heard.
Mrs Hadley's husband Dave, daughter Kelly and granddaughter Mackenzie escaped the blaze along with the two paramedics but Mrs Hadley could not be rescued and she died in the chair.
Police, firefighters, two more ambulances and the Hazardous Area Response Team were sent to the scene and the Health and Safety Executive is now investigating.
At the inquest opening a medical cause of death was given as fatal burn injuries.
Senior coroner for the Black Country Zafar Siddique said: "There was an incident on April 13, a severe fire in the living room of the property in New Street.
"The deceased had been suffering from a high temperature and fatigue, so her daughter called 999. The ambulance crew assessed her for suspected Covid-19.
"Her oxygen levels were low so oxygen therapy was needed. Within minutes of the paramedic plugging in the oxygen cylinder, sparks were witnessed. It set fire to the armchair where the device was sat.
"Paramedics escaped the house, and family members also left the house.
"By the time the paramedics went back in to rescue Mrs Hadley, the fire had developed too much. She was recovered from the armchair.
"A medical cause of death has been given as 1a) fatal burn injuries.
"I will adjourn this hearing to allow the Health and Safety Executive to investigate and give a report."
Hannah Fullerton launched a fundraising page shortly after Mrs Hadley's death with a target of £10,000 and it has now raised more than £9,000.
To see more, or donate, visit justgiving.com/crowdfunding/hadleyfamily.
Mr Siddique expressed his condolences to the family of Mrs Hadley and adjourned the hearing for a pre-inquest review to take place on June 30, so he can receive an update on an investigation by the Health and Safety Executive.