BBC Health Correspondent James Westhead reports from the inquest

The malfunction happened just hours after an unauthorised trainee fitted it with the wrong piece of equipment.

A coroner ruled on Wednesday that baby Hannah Shepherd had died of natural causes at Guy's Hospital, London.

But she added that it was of concern that an unsupervised trainee had been allowed to change essential parts of the machinary.

She called on the government to consider introducing greater regulation in this part of the medical profession.

Heart condition

Although Hannah had appeared healthy at birth, it soon became obvious that she had serious heart problems, an inquest at Southwark Coroner's Court heard.

She had been put on a ecmo-machine which took over the function of her heart and, to a lesser extent, her lungs following a major operation last May.

During the night the machine needed to have a filter replaced, the court heard.

A perfusionist, who is responsible for maintaining and regulating such life-support machines, was called out to deal with the repairs.

However, the court heard that Dr Mohammed Majeed was unaccredited in the UK, even though he had 12 years experience in South Africa.

Under Guy's hospital regulations this meant that he should have been supervised while he carried out his work, as in the UK he only counts as a trainee.

Two senior technicians have had their management responsibilities suspended since the incident.

Clogged

A few hours after the filter had been replaced, the machine clogged up with blood and, when the pressure became too great, sprayed blood around the room.

Gillian Satterly was the sister on duty that night. She told the inquest at Southwark coroner's court that she had been "concerned" about the position of the filter.

She said: "The locks on the circuit concerned me. We didn't normally have a clamp or a bag like we had with Hannah.

"A tube blew off and whirled around the room. I immediately put my finger on the end of the tube to stop the blood coming out.

"Hannah lost a lot of blood and her blood pressure dropped after the incident."

Revival efforts

Despite doctors' efforts to revive her, Hannah died shortly afterwards.

The pathologist's report said that her heart condition was so serious that she would have died anyway.

Pathologist Professor Anthony Risdon said: "The failure of the ecmo-machine brought to an end a period of suspended animation but it did not cause her death."

But the coroner said it was still a cause for concern that the machine had been attended by a trainee, as this had led to such distressing consequences.

The Society of Perfusionists of Great Britain and Ireland said regulation of the profession was long overdue.

Dr Gerry Webb is a perfusionist and secretary of the society. He said that in the past there had been fatalities caused by perfusion accidents.