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H1N1 (Swine Flu): Preparing for the Sickest of the Sick – Three Studies of ICU Treatment of Critically Ill H1N1 Patients

October 13, 2009

In the latest issue of the Journal of the American Medical Association (JAMA) there were three reports on the treatment of critically ill H1N1 patients.  This is an important body of work and will assist clinicians in intensive care units (ICUs) this fall that have been treating patients largely without empirical data about the nature and severity of disease.  I think you will find it pretty interesting too!

The Mexican and Canadian study noted striking similarities in their findings:

  • The Mexican researchers conducted an observational study of 58 patients admitted to 6 ICUs in Mexico City with H1N1-related disease during the initial outbreak in spring 2009.
  • The Canadian colleagues conducted a similar study of 168 critically ill patients in 38 Canadian ICUs –  29 people died, including 21 women and four children. Most died quickly.
  • Patients tended to be relatively healthy adolescents and young adults who developed a brief illness followed by rapidly progressive respiratory failure.
  • Shock and multisystem organ failure were common.
  • Patients experienced low levels of oxygen in their arterial blood (Hypoxemia ) which was prolonged and severe, requiring on average 12 days of mechanical ventilation and frequent use of significant rescue therapies.
  • In Canada, the average patient was 32.3 years old, but 50 patients were children.
  • The influenza outbreak lasted about 3 months in both countries, but the peak lasted just a few weeks, during which time hospitals struggled to accommodate the increased patient load, with 4 Mexican patients dying while awaiting ICU beds.
  • Notably, the Mexican study group incurred a mortality rate twice as high as that in Canada. In both cases there were no documented cases of hospital transmission.

The Australia and New Zealand is based on data from all centers providing extracorporeal membrane oxygenation (ECMO) for H1N1-related disease in Australia and New Zealand during the 2009 Southern hemisphere winter.

  • The cases were typically young adults with little underlying diseases who developed severe hypoxemia and multisystem organ failure.
  • The median duration of ECMO support was 10 days, and the case-fatality rate was 21%.
What is extracorporeal membrane oxygenation (ECMO)?  ECMO is a special procedure that uses an artificial heart-lung machine to take over the work of the lungs (and sometimes also the heart). ECMO is used most often in newborns and young children, but it also can be used as a last resort for adults whose heart or lungs are failing.

What is extracorporeal membrane oxygenation (ECMO)? ECMO is a special procedure that uses an artificial heart-lung machine to take over the work of the lungs (and sometimes also the heart). ECMO is used most often in newborns and young children, but it also can be used as a last resort for adults whose heart or lungs are failing.

How then might hospitals within a given region respond to the unique needs of the sickest patients with H1N1?

  • One possibility is regionalization of care for patients with advanced respiratory failure. This would allow a few centers to accumulate experience managing the sickest patients, while preserving the resources at outlying hospitals for other patients. Strengths of this approach are the possibility for improved outcomes due to accumulated experience and the potential for streamlined conduct of clinical trials of promising treatments.
  • A second possibility is the development of telemedicine consultation for clinicians at outlying hospitals who may benefit from expert clinical advice for such tenuous patients. Demonstration projects are ongoing for telemedicine during a public health emergency.
  • A third possibility is for hospitals to make temporary staffing changes to ensure the continuous presence of clinicians competent to handle these cases. This approach lacks some of the potential benefits of regionalization and may be infeasible because of foreseeable workforce shortages during a severe influenza outbreak.
ECMO Machine in an ICU

ECMO Machine in an ICU

The large proportion of critically ill patients with H1N1 who survived is an important reminder that the medical response to a respiratory pandemic is very different today than it was for the 1918 influenza pandemic. The widespread availability of antibiotics, antiviral agents, vasopressors, and mechanical ventilation makes it possible to save many patients who would not have survived in 1918. With this potential comes an obligation for hospitals and public health systems to collaboratively develop strategies to ensure that, if there is a resurgence of 2009 influenza A(H1N1), the benefits of intensive care medicine can be offered to the maximum number of patients. Although guidelines and recommendations exist for augmenting hospital surge capacity, their implementation in individual hospitals is far from complete.

The investigators from both Mexico and Canada noted that the health care systems struggled to meet the demands created by the increased patient volume, a sobering observation given that the absolute number of excess ICU admissions was modest.

The authors concluded that hospitals must develop explicit policies to equitably determine who will and will not receive life support should absolute scarcity occur. This triage or rationing will be difficult but as in Katrina there may be no other choice. Any deaths from 2009 influenza A(H1N1) will be regrettable, but those that result from insufficient planning and inadequate preparation will be especially tragic.

JAMA. 2009;302(17):(doi:10.1001/jama.2009.1539) http://jama.ama-assn.org/cgi/content/full/2009.1539

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