From inside his Mercedes van, Mike Loveless watched as a man stumbled towards him, his white shirt soaked in blood, dripping from his smashed up nose.

A few metres away another young man, his shirt sleeves also stained blood red, slumped against a parked car and punched uselessly at the keyboard of his mobile phone.

All around others staggered; dazed and confused, some crying and bloodied, like survivors in the aftermath of a disaster. But there had been no bomb, no train crash or motorway pile up. This was the fallout from the last Saturday night before Christmas when hundreds of young men and women, their flimsy tops no barrier to the freezing temperatures, swarmed from bar to club to bar in search of pleasure.

Parked on a strip of Cardiff city centre known as "animal farm", Mr Loveless, a paramedic with 18 years experience, had the unenviable task of picking up the pieces.

In a pilot scheme running in south Wales, Mr Loveless spends his 10pm to 4am shift at the heart of the Christmas revelry answering 999 calls to leave the main fleet of ambulances free to answer serious incidents elsewhere.

He assesses the patients at the scene, carries out treatment and, if necessary, sends them to hospital in a non-emergency back-up ambulance.

The government has been keen to appear tough on alcohol-fuelled violence and the Home Office has launched a "Christmas blitz" on binge drinking. Police can hand out on-the-spot fines of £80 to troublemakers and are targeting pubs and shops selling alcohol to under-18s.

Critics, including the Conservatives, greeted the scheme with scepticism and claim it is intended to grab headlines rather than make a real difference, but a similar scheme in the summer resulted in 4,000 on-the-spot fines and more than 5,000 arrests.

Since then, the police have been given more powers, including the introduction of instant fines for buying or selling alcohol to under-18s and the penalty for being drunk and disorderly rising to £80.

As part of the Christmas crackdown on anti-social behaviour, Mr Loveless works with police officers who roam the streets of the city centre. They call on his medical skills when needed, and in turn go to his aid if the crowd becomes hostile.

"I am linked into the police radio for security," said Mr Loveless. "There are a lot more people carrying weapons these days. A lot feeling they have nothing to lose, all drink and drugs fuelled.

"I've had my arm broken and I've been given a black eye in this job, so I am in constant touch with the officers."

The night is still in its infancy when the radio crackles to life with a 999 call to the Old Borough pub, where a young woman has fallen head first down some steps. A group of young women, fuelled by the festive offer of any three bottles for £5, chants: "Get your kit off for the girls."

It takes half an hour to check the young woman over, lay her on a spinal board and lift her up the stairs and into a waiting ambulance to be ferried to hospital.

Moments later a call for assistance at Edwards bar comes in from the police - "male assault victim hyperventilating".

At the scene, two girls dressed as Christmas tree angels weep and hover over a young man, lying flat on his back on a bench, his face a mess of blood. As the casualty is put into the back-up ambulance for treatment, a teenage boy runs across the street screaming and sobbing to the paramedic: "Pentwyn, pentwyn, pentwyn, I need to get to Pentwyn, please I only got a £1, please."

"Listen mate, I'm not a taxi service okay. Go away or I'll call the police," Mr Loveless responds. "You have to be a bit assertive with them sometimes," he says. "Because otherwise it is like the lunatics running the asylum."

Throughout the night the rapid response van races up and down the street and its offshoots, where every second building is a late night bar, dealing with everything from intoxicated, weeping girls who have fallen off their high-heeled shoes to testosterone-fuelled men with bloody faces, suspected heart attacks and broken legs, and female victims of assault, like Sophie.

Her Christmas celebrations came to an end when a man in The Yard bar punched her in the face, splitting her cheek and plumping her eye out in a black, blue and red mess.

"I've never in my life had a mark on my face, oh my God, look at me, my mum is going to kill me," weeps the 20-year-old, before being ferried away to the University College hospital, Wales.

As night becomes early morning the response team flies from one call to another.

As Mr Loveless treats his patients, around him more police pour into the street, blue sirens flash the length of the road, a fire engine adds its wail to the mayhem and the ambulance control sends a message over the radio to all crews: "A lot of fighting going on in the city centre, it's very dangerous, be careful."

"Merry Christmas to you all," shouts a reveller as the response van pulls up to a ruck outside the Chip Shop.

A well dressed businessman, out with his wife, slips and spills curry sauce over the T-shirt of another man. "He just went for him.

"He went ballistic, and headbutted him," said the businessman's wife.

Then there is the 20-year-old subject of three 999 calls; one over a broken leg which turns out to be a grazed knee, another for an assault and the third when she collapses shivering and drunk in the street.

"I've had enough of this," said the paramedic, sending her to hospital.

Heading back to police HQ at 4am - after answering 21 calls and treating nearly double the number of patients - he adds: "Roll on New Year's Eve."