Keys to managing cases of severe influenza A (H1N1)v in the emergency department

Boqué MC, Rello J

An outbreak of new influenza A (H1N1)v was declared in April 2009, and on Juny 11 the

World Health Organization declared a level 6 pandemic. The diagnostic criteria are the

same as those for seasonal influenza: the sudden onset of a high fever, cough, sore

throat, and muscle pain. Symptoms are usually mild and remit within 3 days, but a small

percentage of patients have fever and progressive respiratory difficulty beyond that

point. Paradoxically, in contrast with seasonal flu, patients over the age of 65 years who

have chronic diseases make up less than 10% of the cases of the new influenza. A

minority have primary viral pneumonia and respiratory distress. The patient profile is a

35-year-old male who, after 3 days with fever, develops progressive hypoxemia requiring

intubation within 24 hours of admission. Adolescents and young adults make up the

largest population group affected and illness is particularly severe during pregnancy,

during the postpartum period., and in obese patients. In children, this influenza often

presents with croup and bronchiolitis, although the respiratory syncytial virus is the main

cause of those clinical pictures. Respiratory frequency should be monitored and a rate of

more than 25 breaths/min considered a warning sign of severity. Continuous monitoring

with a pulse oximeter is also advised and a fall in oxyhemoglobin saturation below 95%

is another marker of severity. Steps should be taken to isolate patients to prevent

transmission of the virus to health care staff or other patients. If complications or risk

factors are present, oseltamivir should be started promptly, even if the patient has been

ill for longer than 48 hours.

Boqué MC, Rello J