Emma Currell, 32, was rushed to Watford General Hospital when she suffered a seizure in hospital transport taking her home from dialysis treatment in 2020.

The inquest at Hatfield Coroners' Court heard that Emma, who lived with nephrotic syndrome - a kidney disorder that means too much protein is passed into protein in the urine - suffered a second seizure as she waited to be seen in Accident and Emergency.

She needed a CT scan and an anaesthetic team was called to sedate her as her tongue swelled and she bled from the mouth.

A tube that should have been placed in her trachea, the windpipe, to allow her to breathe was mistakenly placed in her oesophagus, the food pipe.

Emma, who lived in Hatfield and was mother to a six year old, went into cardiac arrest and died that night on September 5, 2020.

After the inquest Emma Currell's sister Lauren said: 'Today was the hardest thing to bear for my family since Emma died. We're glad at least to have some clearer answers as to what happened.

'We will never get over Emma's death. The hospital has said that they have now put in place improved procedures and training to ensure this type of devastation never happens to anyone else. We trust they will fulfil their promise.'

Emma Kendall, representing the family in an ongoing civil claim, said that 'The Royal College of Anaesthetists ran the No Trace=Wrong Place campaign in 2019 precisely so that this type of catastrophe never occurs.

'All it takes is a few minutes training so that staff can operate safely. This tragedy should simply not have happened.'

Dr Sabu Syed, a trainee anaesthetist, told the hearing: 'Initially the tongue was incredibly swollen and a lot of blood was coming from the mouth. I used suction to remove blood and I was able to push the tongue to the side and got a partial view.'

She said she believed she inserted the tube into the trachea, but now knows it was the oesophagus.

Dr Syed said she asked her senior colleague Dr Prasun Mukherjee to check the position of the tube. 'Dr Mukhejee was busy doing other tasks.

I had a look myself. Unfortunately her tongue was more swollen.'

Technician Nicholas Healey said he tested the machinery when there was no carbon dioxide reading. He said: 'There was nothing to indicate a leak in the machine.

'I was not confident the tube was in the right place. I escalated that to the team.

'A couple of doctors listened to her chest and they were confident there was a reaction.'

He said that both he and Dr Syed had raised concerns about the tube being in the wrong place.

Dr Mukherjee told the hearing: 'I had confidence in my colleague that the tube was appropriately placed.'

Graham Danbury, the deputy coroner for Hertfordshire, asked him: 'Did you, with greater experience, consider that you should have done the administration?'

He replied: 'It is difficult.' He said younger colleagues needed to gain more experience.

Dr Mukherjee said he still detected breathing after the tube was inserted and had assumed the machine readings had malfunctioned and there was a problem with the monitor.

He said he was also concerned about the risks of removing the tube and the danger of surgery.

Asked if it had crossed his mind to summon a more senior colleague, he said: 'I probably did not have enough time to ask for external help.'

He said: 'Retrospectively and with hindsight we know the tube was in the wrong place.'

He agreed he had made the wrong decision, saying that at the time they were dealing with the Covid pandemic.

Dr Thomas Sanbach, who carried out a serious investigation report after Emma's death, said a guideline checklist had been drawn up for trachea procedures outside the operating theatre at Watford Hospital.

There is also to be simulation training for staff and the presentation of a video to staff from the Royal College of Anaesthetists entitled No Trace = Wrong Place, a safety campaign aimed at those who manage patients' airways.

In his conclusion the coroner said: 'Because she was fitting she needed to be sedated to be fit to go into CT machine. Her tongue was swollen making viewing into her mouth difficult. Dr Syed had the responsibility of inserting the tube.

'It was inserted and we now know it was inserted into the oesophagus rather than the trachea.'

He said possible 10 minutes elapsed before it was noted her blood pressure was low and the disappearance of carbon dioxide readings had not been acted on for a considerable period of time. She suffered cardiac arrest and it was not possible to resuscitate her.

'It is accepted by the hospital that the tube was initially in the wrong place and Dr Mukherjee said action should have been taken sooner,' he said.