York Hospital was not to blame for the death of a 59-year-old teacher during a routine operation, an inquest heard.

Susan Dorothy Lumsden, of Sinderby, near Thirsk, died on January 30, 2002, while undergoing exploratory surgery on her throat at the hospital.

But York Coroner Donald Coverdale said Mrs Lumsden's death, which was caused by gas embolism - oxygen entering the right side of the heart, due to surgical emphysema, when air escapes into the tissues of the neck and chest - was not the fault of the surgeon or anaesthetist. He recorded a verdict of death by misadventure.

He said: "It seems a curious course of events. I haven't received evidence that there was any error or mishap or any matter that could, even with the benefit of hindsight, have been done differently."

The coroner said the technique used by hospital staff was a recognised one and there was no record that it had ever caused gas embolism in the past.

Mrs Lumsden, who was a keen soprano, had visited York consultant Andrew Grace complaining of hoarseness and excess catarrh. He discovered a white patch on the back of her larynx and advised her to have a biopsy and exploratory surgery.

During the surgery, Mrs Lumsden's oxygen levels fell and attempts to resuscitate her failed.

Her widower, David Lumsden, said he had left his wife at the hospital that morning while he carried out some business in York. He returned at lunchtime to discover she had died in the operating theatre.

Pathologist Carl Gray said the source of the oxygen, which entered Mrs Lumsden's heart, was most likely to be from an 8cm needle, which was placed through her neck by the anaesthetist to ventilate her for part of her operation.

The anaesthetist, Ian Jackson, said he no longer took part in ear, nose and throat operations and the jet ventilation technique using the needle was no longer used in York Hospital.

He said: "I have done a lot of soul searching in the past 15 months. For the past few months I have not done any ear, nose and throat surgery at all.

"I felt so anxious about it when anaesthetising patients, I just couldn't do it any more."

The anaesthetist said he still didn't know how Mrs Lumsden's death had happened.

A spokesman at York Hospital said: "We understand that this has been an extremely difficult time for Mrs Lumsden's family and would like to extend our deep regret and sincere sympathies to them. Indeed, everyone involved has been utterly devastated by this tragic incident.

"We have been in close contact with Mrs Lumsden's family and share their concern around the uncertainly surrounding her death.

"The trust is constantly reviewing its operating theatre systems and procedures and learning from how other trusts operate to see if we can do things better.

"Despite not knowing how this sad event occurred, we have taken the opportunity to look again at these systems and procedures."

Updated: 10:30 Friday, May 16, 2003