Six members of the Washington Capitals skated through a light practice in Bloomington, Minn., yesterday and General Manager Max McNab said, "I'm holding my breath until they get back."

He was not kidding. There is little incentive for jokes among the Capitals these days. Instead, there is an almost fatalistic mood of waiting to see who will be next to be listed on the medical report.

The most recent victim was defenseman Paul MacKinnon, who suffered a fractured cheekbone, when he was struck in the face by a puck during Saturday's 7-1 loss to the Minnesota North Stars.

MacKinnon and Pierre Bouchard, who apparently suffered a cracked sternum Friday night in Winnipeg, returned here yesterday while the rest of the team journeyed to Montreal for tonight's contest (8:05 p.m.) with the Canadiens.

Bouchard was feeling much better yesterday and there was hope, albeit slim, that the crack shown in the X rays might have been the aftermath of a previous injury. Another examination will be conducted this morning by Dr. Pat Palumbo.

McNab found MacKinnon's injury almost unfathomable, since it appeared when MacKinnon left the ice that he was merely headed for a brief stiching job.

"He kept in the play," McNab said. "Ninety-nine out of a hundred with that type of injury would drop to the knees. I don't know how long he'll be out, but eventually we'll have to come up with some sort of protective device for him to wear."

'To replace Bouchard and MacKinnon tonight, Pete Scamurra and Gord Lane were summoned from the rapidly dwindling stockpile of players here. Scamurra has not played since he suffered a jammed thumb in Vancouver Oct. 27. Lane has been idle since taking a foolish penalty late in the game at Edmonton the following night.

Tonight's visit to Montreal marks the Capitals' ninth road game in their first 13 and concludes a portion of the schdule that has proven every bit as difficult as was foreseen at the start of the season.

"It's been murder," said Coach Danny Belisle. "We have a young team and to get your feet wet in this league starting out with nine of 13 on the road, it isn't easy.

"A few wins early would have been a great confidence-builder. Even if we'd started at a .500 pace against reasonable opposition, the guys could have gotten confidence before going against Montreal and other good hockey clubs.

"The injuries could have meant a couple of games of the first 12, too. Every time we turn around, every game we play somebody gets hurt. I've never seen anything like it in all my years in hockey."

The Canadians scored twice in the last two minutes to tie the Capitals here on Tuesday, 2-2, and maintain their record of never losing to Washington in 33 meetings. Criticized by the Montreal media for that tie and a previous loss to Quebec, the Canadians rebounded to whip Minnesota, 5-1.

Saturday, the stumbling Stanley Cup champions were beaten at home by Philadelphia, 5-3. It seems certain they will face more critcism from perfectionists in the French press and they are likely to be snarling tonight. p

Bunny Larocque will be in the nets for the Canadians in place of Denis Herron, who played a stellar game in that 2-2 tie. Herron suffered a bruised shoulder Saturday night, but is expected to return to action later in the week.

Still, it is not a cheering prospect for the Capitals, especially with that added burden of wondering who is going to feature the next medical report.