A physiotherapist from Derry who died after visiting an Indonesian volcano may not have had an adequate supply of oxygen to her brain, an inquest has heard.
A court in Singapore also heard Lisa Orsi may not have received timely medical care.
The 22-year-old fell critically ill during a holiday on February 20 this year and never regained consciousness.
An inquest into her death heard she was likedly to have suffered from high-altitude cerebral oedema - an accumulation of fluid and resultant swelling to the brain.
Ms Orsi had been on a trek to a high mountainous region with friends on Mount Bromo in East Java when she took ill.
Investigation officer Chia Hong Kai told the inquest Ms Orsi had flown to Surabaya on February 18 and met five friends.
During the journey to their hostel - which was located 2,300m above sea level - she was observed to be unwell.
Her friends said she had been blowing her nose a lot and hard and she had complained of an earache and feeling tired during the trek to the volcanic crater.
She was flushed and panting following a walk outside the hostel and complained of stomach cramps.
Ms Orsi was found lying face up in the shower the following day.
The court heard she was taken to a clinic before being transferred to a hospital and then to Surabaya’s Siloam Hospital for neurological treatment - seven hours after she collapsed.
It was revealed she Ms Orsi vomited twice on the way to hospital and a doctor found her brain had swelled.
She had also fallen into unconsciousness.
She was moved to Singapore General Hospital on February 25 and put on mechanical ventilation.
Dr John Ng, an associate consultant at the department of neurology, said Ms Orsi was likely suffering from high-altitude cerebral oedema - an accumulation of fluid and resultant swelling to the brain.
She was pronounced dead on March 4.
Her organs were donated and had the potential of helping save more than 50 lives.
State Coroner Marvin Bay is scheduled to give his findings on September 22.