Emergency rooms and intensive care units worldwide will experience the heaviest burden of patient care during the H1N1 influenza pandemic, the World Health Organization (WHO) said.

Some H1N1 patients are developing severe pneumonia, which causes respiratory failure within 24 hours, and therefore require immediate admission to an ICU for mechanical ventilation, the WHO said.

Conventional ventilatory support did not help some of these patients, making the treatment more difficult and demanding, doctors from across the world said at the WHO-hosted meeting on 14–16 October.