Monday, November 23, 2009

Novel H1N1 influenza in hospitalized patients

JAMA has a recent issue devoted to this topic. Here’s what stands out:

In a series from California admitted patients tended to be younger (27) but of those admitted, those over 50 had the highest mortality (11% overall, 18-20% for those over 50). 66% of chest xrays showed infiltrates and 31% of patients required ICU. Viral pneumonia and ARDS were the most common causes of death. Secondary bacterial infection was only found in 4%.

A Canadian series looked at critically ill patients. Mean age was 32 and 28 day mortality was 14%. Patients’ illnesses progressed rapidly with a mean of 1 day from hospital admission to ICU transfer. Shock and nonpulmonary organ failure were common. Hypoxemia tended to be severe with the mean PO2/FiO2 of 147. 81% got mechanical ventilation with a mean duration of 12 days. Lung rescue therapies were commonly used.

A series from Mexico reported similar outcomes with additional findings of note: 31% were obese and antiviral treatment (adjusting for those with no opportunity for treatment due to early death) improved survival.

Investigators from Australia and New Zealand reported on a series of patients referred for ECMO. Those patients had a 21% mortality by study end. Patients transitioning to ECMO had a median PO2/FiO2 of 56 on a median of 18cm PEEP.

An editorial, commenting on a trial published in the same issue showing non-inferiority of surgical masks compared with N-95s noted that we still don’t have enough evidence on this issue and the controversy will continue.

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