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Studies: No In-Between With Swine Flu. It's Either Mild -- Or Critical.

Either you get a mild case - or it almost kills you, and they still don't know why: Swine flu is mild for most people, but some become so gravely ill

Either you get a mild case - or it almost kills you, and they still don't know why:

Swine flu is mild for most people, but some become so gravely ill that they require sophisticated techniques, equipment, and aggressive treatment in intensive-care units to survive, according to three new studies.

"This is the most severely ill that we've ever seen people," said Anand Kumar, lead author of one of the studies and ICU attending physician for the Winnipeg Regional Health Authority in Canada. "There's almost two diseases. Patients are either mildly ill or critically ill and require aggressive ICU care. There isn't that much of a middle ground."

Some of the patients Dr. Kumar and his colleagues saw were so sick they had to be saved with a technology similar to one used for patients undergoing heart bypass.

The studies of critically ill patients in Canada, Mexico, Australia and New Zealand, published online Monday in the Journal of the American Medical Association, suggest that intensive-care units could be stretched as a second wave of H1N1 swine flu builds in Northern Hemisphere countries such as the U.S.

American public-health and hospital officials have expressed concern that the country's intensive-care facilities may not be up to accommodating the swell of patients they could potentially end up with in large-scale outbreaks.

An advisory panel to President Barack Obama warned in August of one scenario in which as many as 300,000 patients could require intensive care, occupying between half and all of ICU beds in affected regions at the peak of infection. Such a scenario "could place enormous stress on ICU units, which normally operate close to capacity," the panel warned in a widely publicized report, which also said as many as 90,000 people could die of the disease.

The patients analyzed in the three JAMA studies deteriorated very rapidly after entering the hospital, quickly progressing to respiratory failure, shock, and organ dysfunction and failure. They spent prolonged periods on mechanical ventilators, and some required frequent "rescue therapies," or treatment to save them from life-threatening conditions.

In Canada, Australia and New Zealand, doctors turned to an advanced technology similar to one used for cardiovascular surgery when prolonged mechanical ventilation and other therapies proved not to be enough for some H1N1 patients. "Extracorporeal membrane oxygenation," or ECMO, acts as a lung machine, circulating a patient's blood through a system that adds oxygen. The severely ill patients' lungs were so filled with fluid they couldn't get oxygen to their blood.

Of 68 patients treated with ECMO in Australia and New Zealand, 54 survived and 14 died, according to one of the JAMA studies conducted by researchers in those countries. The median age of the patients was 34 years and included pregnant women and obese patients.

In the study led by Dr. Kumar, 168 critically ill patients in Canada, with an average age of 32 years, generally had symptoms for about four days before being hospitalized, but they deteriorated rapidly after that, ending up in the ICU within a day or two. Most had an aggressive form of viral pneumonia, he said. About 98% suffered from other health conditions, but only 30% had serious underlying health problems such as congestive heart failure or immune suppression.

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