An early morning jogger raised the alarm when he spotted the man in “significant distress” at the home in the Grange just before 5.30am Thursday.
Police said his alleged attacker, a 44-year-old woman, then set several items alight and barricaded herself in the bathroom while the couple’s two children slept nearby.
The children – 11 year-old-boy and a nine-year-old girl – woke when the home’s fire alarms were activated.
Detective Superintendent Andrew Massingham said the injured 43-year-old man was lucky to be alive with the kitchen blade just missing his heart.
“He is extremely lucky … the gentleman would have lost a lot of blood very quickly and he may have become incapacitated up here and we simply would not have known,” Massingham said.
Police believe the injured man pulled the knife from his wound and tossed the blade into his front yard where it was later recovered by detectives.
“The man at that time was locked on the balcony … you’ll see the ladders in place,” Massingham said.
“The first thoughts of neighbours and that jogger was to try and remove him as quickly as possible from their balcony and save his life.”
Neighbours could also hear the panicked children calling for help and released them without injury.
Emergency services extinguished the fire before breaking into the locked bathroom and taking the woman into custody.
The woman was treated for smoke inhalation and taken to hospital for treatment, where she remains under police guard.
The injured man is undergoing emergency surgery and remains in a critical condition.
“Our early advice in relation to the 43-year-old man was that his life was in significant danger – paramedics work tirelessly on him,” Massingham said.
“He’s currently in surgery and he’s in critical condition at the Royal Brisbane and Women’s Hospital.”
He said the family was not known to police and no protection orders were in place at the address.
“This appears to be a tragic domestic violence-related incident of a couple who have been together for an extended period and the children aged 11 and nine are, in fact, their children.
“I’d like to thank those members of the public that came to the aid of those children. ”
Police hope to interview the woman later on Thursday as investigations continue.