BOSTON – Trailing 2-1 with 12 minutes to play on Saturday night, the Toronto Maple Leafs could ill afford to lose another centre. Nazem Kadri’s helmet had just been knocked askew by a thundering open ice hit from Johnny Boychuk and Kadri was adamant about staying in the game.

However, Toronto’s head athletic therapist Paul Ayotte wouldn’t have it.

Ayotte put his arm around Kadri and instructed him that they had to find a quiet room at TD Garden to go through the "Modified SCAT 2" test – something required by the NHL in instances where a player may have suffered a concussion.

"They pretty much forced me to (take it)," Kadri said after Toronto’s 3-1 loss to the Boston Bruins. "As I was going through the test, I was getting pretty agitated. I just wanted to get back out there."

It is an example of the more cautious approach that teams now seem to be taking towards head injuries. The NHL quietly introduced a new protocol for assessing concussions coming out of the general managers meeting in March 2011, a time where they were under heavy scrutiny because of the injury that kept Pittsburgh Penguins captain Sidney Crosby on the sidelines for several months.

More than two years later, it is now common practice. The Leafs removed James Reimer from a game against Carolina last month after he was accidentally kneed by teammate Josh Leivo even though the goaltender thought he could continue. And in last year’s Stanley Cup final, Chicago Blackhawks coach Joel Quenneville refused to put captain Jonathan Toews on the ice in Game 5 after he had his "bell rung."

The most notable aspect of the NHL’s concussion protocol is a requirement that players must leave the bench to be examined, something that is much easier said than done in the heat of battle.

The "Modified SCAT 2" test they are administered includes a quick series of questions and exercises that allow trainers to check everything from memory loss to concentration to co-ordination – all of which can be used to determine if a player has suffered head trauma. In Kadri’s case against the Bruins, he passed with flying colours.

"It’s very generic," he said of the test. "(Recite the) month, date, who we played last. It’s things like that. They make you say (the months) backwards and then you’ve got to remember four or five words.

"It’s something that’s mandatory now."

The new protocol is designed to work hand-in-hand with recent changes to rules governing hits to the head and boarding to make the game safer. Brendan Shanahan, who heads the NHL’s department of player safety, has also been given a mandate to hand out stiffer supplemental discipline.

In particular, he has suspended players who make direct contact with an opponent’s head – something Boychuk appeared to do on the play where he hit Kadri. The Bruins defenceman may hear from the league as a result.

Shanahan played a rough-and-tumble game for two decades in the NHL and believes there has been a significant culture change when it comes to how head injuries are dealt with.

"I didn’t have a reported concussion in my career until one occasion in my 19th year when I was actually knocked out cold," Shanahan said this week at the Hockey Hall of Fame. "I know I must have had plenty of concussions. We just didn’t know. I remember having fights and getting hit where I didn’t feel right.

"Just think about it – what is the point of smelling salts on the bench? What is that telling you? (You sniff) and you’re cured? That’s the era that we lived in. The players are a lot smarter now and they know a lot more."

However, in some cases, the players still need to be protected from themselves. Kadri was clearly unhappy that roughly four crucial minutes of game time elapsed between his shifts on Saturday – it would have been even longer if not for two television timeouts – but that was what it took for Ayotte to assess his condition.

"I wanted to get back out there as quick as possible, but obviously there’s a procedure you’ve got to run through," said Kadri. "I didn’t have much of a choice."