Do not underestimate the serious impact of the H1N1 virus, say researchers

A research team has warned medical experts in the Northern Hemisphere not to underestimate the serious impact of the H1N1 (Swine flu) virus with a new report showing that many patients who were critically ill with the virus required prolonged life support treatment with heart-lung machines.

The latest report, released today in the Journal of American Medical Association (JAMA) revealed the extent to which doctors in Australia and New Zealand used extracorporeal membrane oxygenation (ECMO) during the height of the pandemic during June to August 2009.

ECMO is the most advanced and invasive form of life support available for lung failure and has previously been used rarely. This winter, 68 patients suffering severe acute respiratory distress syndrome (ARDS) - a major symptom of the H1N1 virus - were treated with ECMO.

At the time of the report, 54 of the 68 patients had survived and 14 (21 per cent) had died. Six patients remained in ICU, including two who were still receiving ECMO. Sixteen patients were still in hospital but had moved out of ICU, and 32 had been discharged from the hospital.

ECMO takes blood from the body through large plastic tubes and circulates it through a system that adds oxygen. ECMO is generally used for a limited time because of the risks of bleeding, clotting, infection and organ failure. ARDS is a very severe condition where the lungs fail due to the rapid accumulation of fluid within the lungs.

The team was led by Monash University researcher Dr Andrew Davies, Senior Research Fellow at the Australian and New Zealand Intensive Care Research Centre, who said the H1N1 patients admitted to ICU's were suffering symptoms of respiratory failure and there seemed no choice but to use ECMO to try and save their lives.

"We had not used ECMO machines to treat swine flu patients before because the disease was new to us - but now we know the treatment works and despite the severity of patients' symptoms, most survived," Dr Davies said.

The average duration of ECMO treatment was ten days and the patients stayed in the hospital for an average of 39 days.

The research team - Australia and New Zealand Extracorporeal Membrane Oxygenation (ANZ ECMO) Influenza Investigators - conducted the observational study in 15 intensive care units (ICUs) in Australia and New Zealand between June 1 and August 31, 2009.

The researchers looked at a range of factors including degree of lung dysfunction in patients, how many patients were admitted, the duration of treatment and survival.

Dr David Gattas, Intensive Care Specialist at the Royal Prince Alfred Hospital in Sydney said the research information would better prepare ICU's in the Northern Hemisphere for the patients who develop the more severe cases of the virus.

"The findings of the study should be widely read in the Northern Hemisphere and we hope this knowledge will help medical teams who may have to make fast decisions about starting advanced life supports such as ECMO. Many of these severely affected flu victims can survive," Dr Gattas said.