The parents of a four-month-old boy who died after his ventilator failed at a Birmingham hospital are considering legal action.

Lisa Weale and Jason Smith, of Longbridge, spoke out yesterday after the city's coroner Aidan Cotter recorded a narrative verdict on their son Thomas's death at Birmingham Children's Hospital in December 2004.

The family's solicitor said the case highlighted the crisis in the NHS with vastly over-stretched services and the acceptance that, as a result, mistakes would occur.

A three-day inquest at Birmingham Coroner's Court heard how he died five days after surgery to correct a congenital heart defect, common in babies with Down syndrome.

He was placed on a ventilator in the intensive care unit after the operation on December 10 and was making good progress. But Thomas suffered a heart attack the next daywhen the machine failed.

Doctors spent nearly twoand-a-half hours resuscitating him before he was transferred onto a heart bypass machine. A locum doctor, Simon McGuirk, accidentally switched it off 24 hours later and did not know how to turn it back on, the inquest heard.

Instead he put the machine into reverse mode, so it pumped oxygenated blood through the baby's body. Despite several attempts to remove Thomas from the bypass machine, he died on December 15, 2004.

Ms Weale, a 36-year-old administrator, said: "We've not ruled out the possibility of going to court, but we're still deciding what to do next.

"I wanted the coroner to acknowledge the fact it was the ventilator, which I've known from the very beginning, that triggered Thomas's problems.

"I really feel disappointed that he praised the hospital after what happened. I feel that Thomas would not have been in that position if the ventilator had not failed or was inadequately operated in the first place."

She added: "We've still not been told why the ventilator failed, and they shouldn't be taking chances with the such vital equipment it should be working 100 per cent.

"I feel that the care Thomas received was not good enough for him. He deserved to have adequate care. Mistakes were made and they have never actually said that they are sorry."

Recording a verdict that Thomas died of cardiac failure, congenital heart disease and Down syndrome, Mr Cotter said he "suffered irreparable damage" as a result of the prolonged resuscitation.

"I find that it's more likely than not that the ventilator malfunction caused Thomas's cardiac arrest," he said.

"Experts witnesses agreed that irreparable damage had already been suffered before he was placed on the heart bypass machine.

"Although that attempt was unsuccessful, I would want my daughter to be given that chance, however poor the chance of success may be. In my view the hospital was right to do what they tried to do, even though it did not work."

He added that the heart bypass machine being accidentally switched off "played no part in Thomas's death".

"The choice they faced was stark. Either allow him to die or try to use a machine and staff in a way which neither the machine or staff were intended to be used," said Mr Cotter. "However in my view the hospital should be praised for trying to give Thomas that chance."

Afterwards, Mandy Williams, of Birmingham-based law firm Irwin Mitchell who represented the family, said: "It is the family's view that the narrative verdict given by the coroner failed to address a number of key issues of concern that were heard in evidence during the inquest.

"The inquest has gone some way to identifying the reasons for these failings.

"What has been made clear is that both patients receiving cardiac services and staff working in these units are facing a crisis situation.

"Such services in this country are vastly overstretched and it is accepted that as a consequence, mistakes will inevitably occur."

Alan Taman, the hospital's spokesman, said the coroner's verdict was "fair and balanced".

He said: "The trust hope that it has provided the family with answers to their questions and clarification as to the issues surrounding Thomas' tragic death. We hope this will provide some comfort to Thomas' family.

"Once again, the trust wishes to extend its condolences and sympathy to the family."

A spokeswoman for the Down's Heart Group, a charity offering support and information relating to cardiac conditions associated with Down syndrome, said the inquest should serve as a wake up call to the Department of Health.

The spokeswoman said: "Sadly the situation cannot be changed for Thomas' parents, but urgent action is needed to ensure that other parents don't have to face the loss of a much-loved child because the expertise is available to save them but the resources aren't."