A man from Nghe An Province in the northern central region woke up after three days Tuesday but his wife is still in a coma after inhaling toxic fumes from a mixture of coal they burned for heating.
Dr. Nguyen Duc Phuc at Nghe An General Friendship Hospital, who treated the couple after they were rushed in on Saturday last week, said they had been poisoned by carbon monoxide.
He said there is a good chance of Le Thi Thanh losing her memory when she wakes up, if she does.
Thanh, 61, and her husband Nguyen Van Ngo, 65, on Friday night burned a mixture of coal called than to ong (bee hive-shaped coal) that can produce toxic chemical compounds such as sulfur dioxide (SO2), nitrogen dioxide (NO2) and carbon monoxide (CO).
They slept with their doors shut. Their son found them unconscious the next morning.
Tran Danh Linh, director of the hospital, said the couple were not the only ones who have been brought to the hospital in recent days after burning than to ong.
Linh said fumes from the burned coal can cause bronchial asthma and heart conditions, and even coma and loss of memory.
As the northern region gets colder, doctors have warned people to keep themselves warm with proper food and clothes, instead of burning than to ong.
The cold weather itself has seen a lot of children and old people sent to hospitals around the province.
Sixty percent of patients at Linh's hospital are old people with asthma and heart conditions caused by low temperatures. High number of patients at Nghe An Children's Hospital has forced up to three children to share the same bed.