Objective:

To describe the characteristics of patients with influenza A subtype H3N2 requiring ventilatory support during the 2017 outbreak, as well as the evolution of the disease and clinical results.

Materials and Methods:

Retrospective cohort. We included all patients admitted to the Emergency Department with confirmed diagnosis of H3N2 during June 2017, requiring invasive or noninvasive mechanical respiratory assistance, high-flow nasal cannula treatment or continuous airway pressure.

Results:

34 patients were included; 52.9% men, mean age 81 years (Standard Deviation [SD] 10).

Main comorbidities of patients on admission were:

73.5% hypertension, 44.1% chronic obstructive pulmonary disease and 76.5% congestive heart failure. The mean Charlson Index score was 6 (SD 2), the APACHE II median (Acute Physiology and Chronic Health Evaluation II) was 17 (IQR 14-20) and the SOFA median (Sequential Organ Failure Assessment) on day 1 was 5 (IQR 3-7). On admission, 23 patients required noninvasive ventilation, 5 continuous positive airway pressure, 4 invasive mechanical ventilation and 2 high-flow nasal cannula therapy. The rate of noninvasive ventilation failure was 47.8% (95% CI [confidence interval] 26.8-69.4) and finally 38.2% of patients were intubated and mechanically ventilated. Hospital mortality was 52.9% (95% CI 35.1-70.2).

Conclusions:

A high mortality rate was observed among elderly patients with comorbidities during the H3N2 outbreak. Most patients underwent a noninvasive ventilation trial on admission, however a high percentage failed. The initial condition could have been interpreted as acute chronic obstructive pulmonary disease or congestive heart failure.