A 30-stone woman had a fatal heart as emergency services were trying to decide how to rescue her, an inquest has heard.
Carol Beverley suffered a blood clot in her lung before going into cardiac arrest at her home in Wareham, Dorset in April last year.
A series of mistakes were made when on-call paramedics were not told about her size and her blood clot was initially misdiagnosed.
When they arrived paramedics were unable to transfer Ms Beverly from her home to the ambulance as one of their two extra-large vehicles was being used on the other side of the county.
Firefighters were called and were discussing whether to remove a window to get her out when she died.
Giving evidence at the inquest in Bournemouth, Dr Rob Torock said treatment had been missed for pulmonary embolism but it was "unclear" about whether her death could have been avoided.
Ms Beverly’s sister Tessa Griffiths paid tribute to the "beautiful, kind and loving" science teacher and said she missed her "terribly", the BNPS news agency reports.
When the news of the 43-year-old’s death was first announced, staff and students at her school - Lytchett Minster School - described as a dedicated, hardworking teacher.
Headmaster Andrew Mead told the Bournemouth Daily Echo: "Teaching was Carol's life, it was her passion.
"She adored working with young people and inspired many to continue their study of physics to A-level and beyond. Her commitment and dedication were exemplary. She will be sorely missed."
Dorset coroner Sheriff Payne recorded a verdict of death by natural causes.
He said: "An opportunity was missed to provide treatment that may have altered her death. It appears that lessons have been learned and changes are being considered."
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