SINGAPORE: A man who drowned while practising a breathing method underwater likely suffered a shallow water blackout as a result of holding his breath underwater after he had hyperventilated, a coroner has found.
In findings made available on Friday (Jan 14), State Coroner Adam Nakhoda cautioned against practising prolonged underwater breath-holding after hyperventilating, advising such practitioners to have a buddy in the pool focusing on them at all times.
He ruled the death of Mr Danzel Goh Choon Meng, who leaves behind a wife and son, a misadventure. Mr Goh, a company director, was 29.
Mr Goh had gone to a swimming pool at Mimosa Park in the Yio Chu Kang area with his wife on the evening of Mar 27 last year.
At about 7.10pm, a resident entered the pool to swim some laps. He noted that Mr Goh appeared to be doing breathing exercises in the pool and was not swimming laps.
Mr Goh's wife left the pool area at about 7.20pm as she had household chores to do, but Mr Goh remained in the water. About 15 minutes later, the resident completed his laps and left too.
At about 7.50pm, Mr Goh's neighbour walked past the pool area and saw a handphone by the side of the pool. He recognised it as Mr Goh's and thought he must have forgotten to take it home.
He did not see anyone in the pool, but went closer to take a look as he heard sounds coming from the phone.
When he reached the locked gate to the pool area and looked over, the neighbour saw Mr Goh lying at the bottom of the pool. He immediately alerted the security guard at the main entrance to Mimosa Park.
Paramedics were called for while neighbours helped to pull Mr Goh out of the water. He was placed in the recovery position, but did not rouse despite cardiopulmonary resuscitation.
He was taken to hospital but did not regain consciousness, and was pronounced dead at about 9.30pm that night. Closed-circuit television footage showed that he had been submerged underwater for almost 38 minutes before he was rescued.
A forensic pathologist certified Mr Goh's cause of death as drowning.
Mr Goh's wife said her husband was a very fit person who exercised daily, running, lifting weights and doing static training. She described him as a person who would try to push his limits.
She said her husband downloaded the Wim Hof application and had been using it for about a week before his death.
THE WIM HOF METHOD
An expert in the Wim Hof method, Mr Tan Chun Yih, testified that it comprises three components. The first is the breathwork component, which involves breath intake involving controlled hyperventilation, breath retention or holding one's breath; and breath recovery.
Participants would take up to 30 breaths before holding their breath for a period of time. This was described as a form of meditation, where participants will gradually feel the urge to breathe build up.
The second component of the method is cold immersion, where participants immerse themselves in cold water of between 3 degrees Celsius to 6 degrees Celsius for not more than two minutes.
The third component is a mindset component. Mr Tan explained that he would emphasise the safety aspects of the two physical components to his students.
He said it is critical that the breathwork component should never be practised in or near water. Mr Tan said this is because the act of expelling carbon dioxide during hyperventilation would reduce the sensation of running out of breath, allowing the practitioner to hold his breath for longer.
The consequence of holding one's breath longer without the corresponding urge to breathe - that would usually be present if carbon dioxide has not been expelled through hyperventilating - was that the practitioner may faint due to lack of oxygen.
Once he has lost consciousness, he would no longer be able to consciously hold his breath, and would automatically inhale again.
If the person was in water when this happened, he could potentially drown in what is known as shallow water blackout, said Mr Tan.
He said the risks of shallow water blackout are "non-existent" if the breathing component of the Wim Hof method is done in the presence of trained instructors, as they would not allow students to perform it near or in water.
He also emphasised that the breathwork component should not be carried out concurrently during the cold immersion portion of the Wim Hof method.
Mr Tan said the Wim Hof app came with safety instructions and warnings. Before a person could start the breathwork component, a warning screen would pop up emphasising that the practitioner should not be in or near water.
Checks of Mr Goh's phone showed that he had logged records in the Wim Hof app of performing breathing basics from Mar 21 to Mar 26 last year, in the days preceding his death.
SHALLOW WATER BLACKOUT AND RELATED EDUCATION
According to the United States National Centre for Biotechnology Information, shallow water blackout has the potential to affect anyone in the water, even fit and experienced swimmers.
The Division Head for Sport Safety at SportSG, Madam Delphine Fong, said shallow water blackout is most common amongst physically fit swimmers, spear fishermen and free divers.
The most dangerous risk for shallow water blackout comes from repetitive, competitive prolonged breath-holding laps with little rest in between, especially if intentional or unintentional hyperventilation has occurred.
In shallow water blackouts, it takes about two-and-a-half minutes before brain damage and death, she said. In comparison, it takes between six to eight minutes for a person drowning but not experiencing shallow water black-out to suffer brain damage and death.
Mdm Fong said SportSG had been performing research, discussion and statistical analysis on shallow water blackout after an incident in 2008 where a boy drowned during a swimming class in a 1m-deep pool.
SportSG published the Water Surveillance Guide, which has been disseminated to all public swimming pools and at school talks and has a section on shallow water blackout.
SportSG plans to include this as a topic to be included in a technical reference code of practice for water safety to be disseminated to all swimming operators including private pool operators.
CORONER CAUTIONS AGAINST BREATH-HOLDING EXERCISES IN WATER AFTER HYPERVENTILATION
State Coroner Adam Nakhoda said it appeared that Mr Goh had carried out the breathwork component of the Wim Hof method on dry land for six days before his death.
However, he decided to carry it out while submerged in the pool on Mar 27, 2021.
"It was unclear why Mr Goh did not heed the warnings in the Wim Hof app and practised the breathing component whilst in the pool," said the coroner. "Suffice to say this was an activity that was fraught with danger."
"I found that Mr Goh had, of his own accord, embarked on very risky behaviour by choosing to do the breathwork component of the Wim Hof method underwater," he said. "As a result, Mr Goh very likely suffered from shallow water blackout and drowned."
He said a person should not hyperventilate and then practise prolonged underwater breath-holding on their own.
If a person is intending to practise prolonged underwater breath-holding then they should have a buddy in the pool focusing on them at all times.
This is to ensure that the person does not get into difficulties, or for the buddy to safely take the person out of the water if there are any difficulties and provide first aid.
The coroner urged SportSG to continue with its outreach in educating pool operators, lifeguards, swim coaches and the public on the dangers of breath-holding with hyperventilation.
He gave his condolences to Mr Goh's family for their loss.