An asthma sufferer died after losing blood during an operation to remove a diseased lung, an inquest heard.

Leeds Coroner's Court heard that Loretta Margaret Lawton, 43, died on the operating table at Calderdale Royal Hospital, on May 20 last year.

The former spot welder had been admitted two days earlier after suffering respiratory problems and possible pneumonia.

She was discharged the same day, but hours later became short of breath and called an ambulance for herself. On May 19, she was admitted to the Intensive Care Unit at Calderdale Royal Hospital and transferred to Leeds General Infirmary the following day.

Dr Roderick Taylor, a consultant physician at Calderdale Royal Hospital, saw Mrs Lawton on May 18 just before she was discharged. He said her temperature was normal and her oxygen levels had raised satisfactorily.

"She said she felt much better," he told the court. "She told me she had decided to go home. She told me she had stopped coughing up phlegm and she was fully dressed with bags packed."

James Thorpe, a consultant thoracic surgeon at LGI, told the court that when she was at LGI, her oxygen levels were low, her carbon dioxide level was high and she was pale and anaemic. He decided that Mrs Lawton, of Firth Street, Rastrick, should undergo surgery.

"During the dissection process, there were problems getting control of one of the pulmonary veins," he said.

"During the handling of the tissues of the heart, there was a breach which lead to quite extensive bleeding. We got on top of that to a great extent during surgery, but we couldn't salvage this during the operation and she died on the operating table." He compared working on the inflamed tissues of Mrs Lawton's heart to "operating on damp blotting paper."

Dr Leslie Davison who carried out a post mortem on Mrs Lawton, said he found a two centimetre diametre hole in one of her heart chambers. He said this damage was likely to have been caused manually during surgery.

He said her death was caused by haemorrhaging due to a laceration caused by surgery for pneumonia. He said her left lung, which had not been removed, also showed signs of severe pneumonia.

In a statement, Mrs Lawton's husband Peter said his wife was so weak after her discharge from hospital he had to carry her into the house.

Coroner David Hinchliff recorded a verdict of death by misadventure. He said there was nothing to suggest that had the hole not occurred, Mrs Lawton would have made a full recovery immediately.

"Her left lung could have given her considerable problems," he said.