Published Date: 2009-10-01 18:00:04
Subject: PRO/AH/EDR> Influenza pandemic (H1N1) 2009 (61): FLAARDS
Archive Number: 20091001.3419
INFLUENZA PANDEMIC (H1N1) 2009 (61): FLU A-ASSOCIATED ACUTE RESPIRATORY
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Tue 29 Sep 2009
Source: Bloomberg News [edited]
Inflamed, flooded lungs trigger death by swine flu
Swine flu [influenza pandemic (H1N1) 2009 virus infection] is most
dangerous when it causes the lungs to become inflamed, flood with fluid,
and fail to function, doctors in Australia and New Zealand have found.
While a majority of people infected with the virus have a mild illness, a
small number develop life-threatening disease, intensive care specialists
Steven Webb and Ian Seppelt said. They described the most common of 3 main
complications from the pandemic 2009 strain as "flu A-associated acute
respiratory disease syndrome", or "FLAARDS."
"FLAARDS -- sometimes with associated multiple organ failure -- is the most
common syndrome and has the highest attributable mortality," Webb and
Seppelt wrote in an editorial in the September  issue of the medical
journal Critical Care and Resuscitation [text and abstract not yet
available. - Mod.CP]
The new pandemic (H1N1) 2009 influenza strain has killed at least 3917
people and spread to 191 countries and territories since its discovery in
Mexico and the US in April 2009. Hospitals in the Northern Hemisphere are
bracing for a surge in flu cases in coming weeks, spurred by colder weather
that promotes its spread. In Australia, flu patients occupied a quarter of
beds in intensive care units last winter  and 178 died.
Cases may be peaking in Hong Kong. Average daily attendance at the city's
accident and emergency departments rose from 6354 in the last week of
August  to 7086 last week [week of 21 Sep 2009], according to a
government statement on 25 Sep 2009. The virus has killed at least 23
people in Hong Kong.
Intensive care doctors in Australia and New Zealand are pooling data on
more than 400 swine flu cases to describe disease patterns and treatment
strategies, and inform the Northern Hemisphere countries about what to
expect this winter [2009-10]. "ICUs [intensive care units] are the 'canary
in the coal mine'," Webb and Seppelt wrote in the editorial. "It is only by
documenting the severe cases requiring intensive care that it is possible
to get an idea of the overall impact of this new disease."
In Victoria, Australia's 2nd most-populous state, the pandemic virus
sickened about 5 per cent of the population, with 0.3 per cent of infected
patients being hospitalized, health officials said in a study yesterday [28
Sep 2009] in the Medical Journal of Australia. One in 5 people admitted to
the hospital were transferred to an ICU, mostly because of severe
respiratory failure. 85 per cent of critically ill patients survived after
staying an average of 9 days in ICU. Almost 3/4 of these patients required
mechanical ventilation to breathe and 7 per cent needed to have their blood
pumped through an artificial lung in a procedure known as extracorporeal
membrane oxygenation, or ECMO.
In most cases, flu remains in the nose, throat and bronchi, where it causes
a runny nose, sore throat, and cough until the body's immune systems
eliminates it, usually within a week. The new pandemic (H1N1) 2009 strain
may be at least 1000 times more adept than seasonal flu at infiltrating the
lower branches of the airway, said Yoshihiro Kawaoka, a virologist at the
University of Tokyo, who has studied the viruses in non-human primates. In
severe cases, influenza can damage the capillaries surrounding the tiny
grape-like sacs, known as alveoli, where gas is exchanged through the
blood. Damaged alveoli can bleed, causing pulmonary hemorrhage and blood
clots. Inflammatory substances are produced by the immune system to fight
the infection and repair the damage. An over-exuberant response can worsen
the effect by filling the lungs with fluid and cause permanent scarring
that restricts lung function.
Besides FLAARDS, the other predominant disease patterns associated with the
pandemic flu virus are community-acquired bacterial pneumonia and an
exacerbation by the virus of airflow limitation, Webb and Seppelt said.
Life-threatening infection may be more common in people with underlying
health conditions, including morbid obesity, type-2 diabetes, cancer, a
weakened immune system, and chronic lung disease, they said. Pregnant women
and those who recently gave birth also appear at higher risk.
Still, "many patients with FLAARDS are young and previously well," they
said. In Australia, the median age of people dying from seasonal flu is 83.
In the case of the novel pandemic (H1N1) 2009 virus, it is 51 years, the
health department said in a report last week [week of 21 Sep 2009].
[byline: Jason Gale]
ProMED-mail rapporteur Mary Marshall
[These observations reinforce those described in the preceding ProMED-mail
report [Influenza pandemic (H1N1) 2009 (60): bacterial coinfection
20090930.3410] that bacterial coinfection was observed frequently in lung
tissue specimens from fatal cases of influenza pandemic (H1N1) virus
infection in the USA. - Mod.CP]