Sergeant Jonothan Rattenbury and PC colleagues Lewis Williams, Chloe Morgan, Harry Matharu also arrived to help restrain the man and carry him down three flights of stairs to the waiting ambulance.
Birmingham Police Inspector Mat Minton, said: "I believe the actions of these officers saved the man's life. They were met with the sight of someone who'd mutilated himself and was outwardly displaying hostility and aggression towards them.
"They had to deal with that while trying to provide emergency first aid. It's hard to imagine how challenging that scene must have been for the officers who first attended - they did a brilliant job.
"Sergeant Rattenberry later described it as a bloodbath and the most gruesome scene he's encountered in 26 years police service."
The man went on to recover in hospital and has since been receiving specialist support.
West Midlands Police has recently joined forces with a drug referral agency in a push to raise awareness of the devastating effects of Black Mamba and to protect members of the homeless community who are being targeted by dealers.
'Black Mamba' mimics the effects of tetrahydrocannabinol (THC), the main psychoactive ingredient of cannabis.
But it is far more potent than natural cannabis and can cause harmful side effects - including hallucinations, psychosis, muscle weakness and paranoia.
Black Mamba is now a class-B drug after it was designated a controlled drug in 2013.
It and other so-called legal highs, like Spice, were completely outlawed when the Psychoactive Substances Act became law last year.
Drug experts have warned of a Spice epidemic that is spreading from the North West, driving a wave of crime and casualties that the police and emergency services are struggling to cope with.
Distressing videos of users on Spice have gone viral, with some shown twitching or in a catatonic state.
Discussing the October incident, Birmingham Police Superintendent Andy Parsons said: "Some people are still viewing Black Mamba as a low-risk drug substitute and are taking it without any consideration for their safety.
"But our view is that there is no safe way to use Spice or Mamba.
"The reality is that these psychoactive substances can have catastrophic effects.
Unscrupulous distributors are making it using dangerous, potent chemicals which can be lethal effect, while the psychological impact can be devastating and lead people to self-harm or harm others.
"We cannot stress enough that Black Mamba is a very dangerous drug. It is also now illegal to possess synthetic cannabis like Black Mamba and Spice so users could end up with criminal records."
What is 'Black Mamba'?
* Black Mamba is a variation of Spice, a synthetic cannabinoid which has similar effects to natural cannabis.
* However it is much more potent and reacts more strongly with the brain's receptors.
* Regular use can cause a relapse of mental health illness or increase the risk of developing a mental illness especially if someone has a family history of mental illness.
* Reported effects include convulsions, shortness of breath, kidney failure and cardiac arrest, as well as hallucinations and irreparable damage to the user's mental health.
