Inquest rules Buckinghamshire woman died from complications of laughing gas use
Ellen Mercer, 24, inhaled two to three "big bottles" of the substance each day, Berkshire coroner's court heard.
Laughing gas abuse contributed to the death of a student from a blood clot, a coroner has concluded.
Ellen Mercer, 24, inhaled two to three "big bottles" of the substance each day, Berkshire coroner's court heard.
She was taken to hospital by the emergency services in the early hours of February 9 last year, after she reported that she was unable to walk and would fall over when she tried.
She was treated by medical staff at Wexham Park Hospital Emergency Department, but she was found unresponsive about 24 hours later, at 00.52am on February 10, and was declared dead at 1.15am.
The inquest heard that a post-mortem examination report found Ms Mercer's death to have been caused by bilateral pulmonary thromboembolism, deep vein thrombosis, and "long-term complications of nitrous oxide use".
Ms Mercer was said to have spent the previous two weeks unable to leave her bed because of her abuse of the substance.
In her conclusions, senior coroner Heidi Connor said that this immobility had contributed to her death.
"Ellen Mercer's death was caused by nitrous oxide abuse and immobility that led to the development of a pulmonary embolism," she said.
Ms Connor said: "This case has highlighted how hugely dangerous it is to use nitrous oxide.
"It is the nitrous oxide which has been the significant cause of her immobility."
The inquest also heard that Ms Mercer had been diagnosed with bi-polar disorder, but local services had failed to follow up on her mental health review.
The inquest heard that emergency services attended the student's home on February 8.
Michaela Kirtley, an emergency medical technician from Phoenix Response Services, a contractor for South Central Ambulance Service, gave evidence to the inquest.
When she arrived she was shown to the bedroom by Ms Mercer's boyfriend.
"There were no sheets on the bed at all. There was just the duvet, severely stained. The room was bare."
She said the scene made it clear to her that she was dealing with a "vulnerable person".
She said Ms Mercer "was talking as normal", and the only one of her vital signs that was outside the normal range was her heart rate, which could have been because of anxiety.
Ms Mercer told her that she had burned her legs after spilling a gas canister on them and that she had been unable to walk or go to the toilet for two weeks, she said.
She said Ms Mercer looked six months pregnant.
She checked the wounds on Ms Mercer's legs, which she described as "pussy".
Ms Mercer's boyfriend showed her a box of gas canisters, which she identified as nitrous oxide.
"I had never seen such big bottles," she said.
She told the inquest that the canisters were 600g and that Ms Mercer's boyfriend said she took "two to three bottles" per day, but had slowed down in the last couple of weeks.
Ms Mercer told her she had passed out and the bottle had fallen on her legs.
An ambulance took Ms Mercer to hospital.
Ms Mercer spent the last 24 hours of her life in the emergency department.
The inquest heard that during that time staff failed to carry out a venous thromboembolism (VTE) assessment.
This could have identified that Ms Mercer was at a higher risk of developing a blood clot.
However, Ms Connor concluded that the failure to carry out the VTE risk assessment did not cause Ms Mercer's death.
The coroner said she would write a regulation 28 report into the use of VTE risk assessments in emergency departments.
This report will be addressed to Frimley Health Foundation Trust, the Royal College of Emergency Medicine, the Royal College of Physicians, NHS England, and the National Institute for Health and Care Excellence.
At the time of the student's death, possession of laughing gas with the intent of getting high was not illegal. It was banned by the Government, and made a Class C drug, in November 2023.