The judge was staggered by Patel's blood-alcohol reading of 406 milligrams per 100 millilitres of blood - more than five times the legal limit of 80 milligrams.
"I'm quite astounded that someone with that reading could manage to engage a car into gear and drive it,'' Judge Callaghan said.
Patel also admitted a dangerous driving charge when the smash happened on Ohoka Rd in Kaiapoi at 3.15pm on August 16 this year.
He crossed a raised centre island, veered towards several groups of high school students walking on the footpath, before swerving left, and colliding head-on with a van.
The level of Patel's drunkenness stunned officers at the scene.
"It's definitely the highest reading I've come across in 16 years of policing,'' said Senior Constable Mike Farrall of Kaiapoi police.
"To speak to (after the crash) he was incoherent. He didn't have a clue what was going on.''
The court was earlier told Patel was convicted of drink-driving two years ago when he was caught with a breath alcohol level of three times the legal limit.
Mr Brandts-Giesen said Patel was stressed because his home and business had been affected by the earthquakes.
He said his client had arrived in New Zealand as an immigrant nine years ago with "only had the clothes he wore'' but had gone on to become a successful businessman.
He said earlier media publicity, with his photograph being published in the New Zealand Herald and local media, had been a heavy punishment for his client, who was contrite.
Patel had not touched "a single drop'' of alcohol since this year's incident and was addressing his alcohol problem through counselling.
He had apologised to the victim, and paid $5800 in van repairs.
His own $10,000 car had been written off.
Mr Brandts-Giesen asked for name suppression because Patel's wife had been verbally abused in the street.
But Judge Callaghan said the public deserved to know what happened to him.
In sentencing Patel, the judge said "There are clearly issues here with the protection of the public and sending out messages to others who might choose to drink and drive; especially at this very high level.''