half that of Mexico because of the wide use of lung machines.
The study found that 29 people (17 per cent) died — most within the
first 14 days after becoming critically sick. Twenty-one (72 per cent)
of those who died were female.
Photograph by: File, AFP/Getty
A "striking" proportion of severe swine flu infections are occurring
among young women, according to Canadian research that shows severe
H1N1 can hit previously healthy teens and young adults hard and fast
in a pattern previously only ever seen with 1918 Spanish flu.
The study shows that severe disease and death in the outbreak is
concentrated in relatively healthy young people, aged 10 to 60. Only
30 per cent had serious underlying health problems, such as cancer,
chronic kidney failure or medication-dependent diabetes.
"Seventy per cent of them would have said to you, 'I'm pretty
healthy.' I think that's pretty startling, quite frankly," said Dr.
Anand Kumar, an intensivist with the Winnipeg Regional Health
Authority and an associate professor of critical care and infectious
disease at the University of Manitoba.
The study found that of the 113 women and 55 men admitted to an
intensive care unit between April and August, the mean age was 32.
Overall, 29 people (17 per cent) died — most within the first 14 days
after becoming critically sick. Twenty-one (72 per cent) of those who
died were female.
"It's a high mortality rate for young people," Kumar said. "When you
bear in mind that these are people from the age of 15 to 55 years old,
you don't see a lot of diseases that have that kind of mortality in a
large group of people that age. These people are people in the prime
of their lives."
Another study, also released Monday, found an H1N1 death rate twice as
high in Mexico. By 60 days, 24 of the 58 patients (41 per cent)
admitted to intensive care with H1N1 in the Mexican study had died.
The major difference between Mexico and Canada is access to high-tech
care, Kumar said.
But there were striking similarities in the findings from both
countries, investigators said: Once admitted to hospital, people with
severe H1N1 rapidly got worse, suffering severe hypoxemia — lower than
normal oxygen in the blood — that required, on average, 12 days of
mechanical ventilation and extraordinary "rescue" therapies to keep
them alive. One such therapy is a machine that takes blood out of the
body, oxygenates it and returns it to the body, similar to a bypass
machine for heart surgery.
"Unlike (heart) surgery, when you do this for a couple of hours, some
of these guys required it for a week or two weeks, or longer," said
"Rescue therapies are therapies that we use when we've got nothing
else left," he said. They are also not widely available in Canada.
Shock and multiple organ failure were also common in the sickest
The Canadian study, by members of the Canadian Critical Care Trials
Group, represents the largest series of patients with severe swine flu
yet described, and includes both adults and children treated at 38
ICUs across Canada.
Apart from usual flu symptoms, the cases "stand out" for the number
that involved gastrointestinal tract symptoms, shortness of breath and
"occasional frothy lung fluid" on cough, or during aspiration, the
Writing in the Journal of the American Medical Association, the team
warns that, if H1N1 infections increase in coming months as expected,
intensive care units will become the choke point.
And an accompanying editorial from doctors at the University of
Pittsburgh School of Medicine warns hospitals need to develop explicit
policies to determine "who will and will not receive life support" if
resources become scarce.
During an outbreak of H1N1 in Winnipeg in the spring, "we went from no
cases to 40 cases simultaneously in the ICU in about three weeks,"
Kumar said in an interview. "It was really quite frightening, because
you don't know where the ceiling is and these guys are absolutely
critically ill. They're the sickest group of patients that I've seen
as a group in my life."
"They typically require two to three weeks of ventilation. That
completely overwhelms your ICU capacity. Your regular patients don't
disappear. You're still at 90 per cent capacity in your beds, but now
you've got to handle an extra 50 or 60 per cent of patients. It has
the potential to be life-threatening, in terms of bed capacity."
Kumar said that, for every three or four people hospitalized with
H1N1, one requires intensive care. "You can overload the ICU well
before you overload the hospital."
About one-third of critically ill patients in the Canadian study were
aboriginal Canadians. Fifty of the 168 patients were children.
As to why women are disproportionately hit, "nobody knows," Kumar
said. In most infectious disease, males make up a lager proportion of
cases, and have a higher death rate. Pregnancy is a risk factor for
severe H1N1 disease. And women, on average, have less lung capacity
As well, obesity has been shown to be a risk factor for severe H1N1
disease. Excess fat tissue might further compromise a woman's lung
Overall, the average time from the onset of symptoms to admission to
hospital was four days, and from hospitalization to admission to an
ICU one day.
Most times influenza should improve after two to three days. "What
you're seeing here is people who are not improving, toughing it out
and then coming into hospital when they start to struggle," Kumar
The most common underlying health problems among critically ill
patients in the study were lung disease obesity, hypertension and a
history of smoking or diabetes.
He said the findings underscore the benefit of vaccination.
"The vaccine risk-benefit ratio is crazy in favour of getting
vaccinated. People should be getting vaccinated."
© Copyright (c) Canwest News Service