TORONTO - Intensive care specialists who rode H1N1's rocky first wave are warning colleagues who've yet to see many of these difficult patients what they have in store.

ICU specialists from Mexico, Toronto and Winnipeg laid out their experiences before a standing room-only crowd Monday at the Critical Care Canada Forum, an annual meeting of intensive care specialists.

"There's very limited capacity to care for patients from the perspective of manpower and the perspective of machines and ventilators in certain parts of the country," Dr. Rob Fowler, an intensive care specialist at Toronto's Sunnybrook Health Sciences Centre, said on the sidelines of the meeting.

"That's because usually the need isn't there. And we're coming into a time when the need may be there and may be disproportionately there in some regions over others."

Fowler was one of the speakers and is one of several researchers internationally who are involved in trying to detail for the rest of the medical community what severely ill swine flu patients go through and how ICU teams have managed to pull survivors through.

He thinks the country will face a challenging time.

"Our system, whether we're in the middle of an urban centre in Canada or if we're in Nunavut or Northwest Territories is, I think, at the baseline usually stretched pretty tightly," said Fowler.

"We operate in the Canadian health-care system without a lot of margin. And that holds for the ability to transport people from one place to another. It certainly holds for transportation capacity in the North."

The bulk of the first wave activity was centred around a few places, Toronto and Winnipeg among them. That means many doctors elsewhere have only seen a few of these cases and may not fully understand what it will be like if their area gets hit with a lot of activity, said Dr. Anand Kumar.

Kumar is an infectious diseases and intensive care specialist in Winnipeg; he was in the thick of it last spring when that city's ICUs were jammed with more than five dozen gravely ill H1N1 patients.

"You've got to see it to believe it," he said. "Honestly, when we got hit, I had a little bit of a difficult time convincing people that we had a serious problem."

The "it" Kumar referred to is bed after bed filled with patients whose lungs are so overwhelmed by their infection they cannot breathe on their own. These aren't the seniors who flu normally attacks. They are teens. They are people in their 20s, 30s, 40s and 50s.

In terms of the overall population, their numbers aren't enormous. But the gravity of their illness makes a huge impact on ICU staff who have had to resort to extraordinary measures to keep these patients alive.

Those who haven't seen it haven't necessarily believed it, Kumar said. But he thinks that may be starting to change.

Kumar noted a friend in Victoria, a fellow ICU doctor, has been calling swine flu "the scam-demic." The friend didn't see the outbreak as much more than seasonal flu making the rounds early.

"He was unconvinced, was what he was telling me," Kumar said.

"He was completely unconvinced as he got his first case, and then as he got his second case. He said he changed his mind on Wednesday when, during that week, he got six patients. And now he's going `Oh my God, my unit is half filled with H1N1 patients.' So he's convinced now."

From the conversations Fowler is having at this meeting, he thinks doctors elsewhere are getting nervous. "I think lots of people are very concerned that they may not have capacity to treat those that are most severely affected."

He is too, especially in regards to capacity to get severely ill patients from where they live to where there are the ICU beds available to care for them.

"Am I concerned? It would be completely wrong of me to say I'm not concerned. Do I think that lots of work has been done? Absolutely. But I'm still worried that our capacity will be stretched."

He said the vast majority of patients who become critically ill with swine flu can be brought through their infection with "aggressive, conventional means of ventilation." But that won't be enough for everyone.

"There's a portion -- and whether that portion ends up being 10 to 25 per cent that can't get that kind of lung help from our usual means -- then those patients are going to need to be considered for transport to other places," he said.

"And if you're in the Miramichi, that can be challenging to get them to Saint John or Moncton or Fredericton. If you're in Iqaluit, well it's doubly challenging because you have a hard time getting people to Manitoba or some place else."

"It goes without saying that because of the geography of this country, it's challenging to provide the same care in all geographies in the same period of time. And it's a concern that people definitely need to work on."

-- Follow Medical Reporter Helen Branswell's flu coverage on Twitter at CP_Branswell.