Severe refractory hypoxaemia in H1N1 (2009) intensive care patients: initial experience in an Asian regional hospital

The management of Influenza A (H1N1) patients with acute respiratory distress syndrome (ARDS) is an emerging challenge, especially during the 2009 pandemic. These patients frequently require advanced mechanical ventilation (MV) and on occasion, rescue therapy. We describe the demographics, presentation, course and outcomes of the first 12 H1N1 patients with ARDS who were admitted to our institution.

This was a retrospective chart review of H1N1 patients with ARDS who were admitted to our intensive care unit (ICU) between July and September 2009.

Seven of the 12 patients were female. The median age was 46 (range 27-66) years. 25 percent of the patients had good health prior to the infection. The presenting symptoms were mainly cough (100 percent), fever (92 percent) and dyspnoea (64 percent). The median times from symptom onset to both hospitalisation and ICU admission were five (range 2-9) days. Ten (83 percent) patients required invasive MV within 24 hours of presentation. The mean PaO2/ FiO2 ratio was 87.9 +/- 37.3 mmHg, with a mean positive end expiratory pressure at 16.1 +/- 7.3 cm H2O. Three patients required either unconventional MV and/or prone positioning, inhaled nitric oxide or nebulised prostacyclin. The mean Acute Physiology and Chronic Health Evaluation II score was 12.7 +/- 9.1. Among survivors, the median number of ventilator days was 7.5 (range 5-11), with a median length of ICU stay of ten (range 6-14) days. The median length of hospitalisation was 13.5 (range 9-31) days. The mortality rate in our case series was 50 percent.

Unlike patients of seasonal influenza, our severe H1N1 patients were of a younger age. A significant proportion had no underlying risk factors. Despite high ventilatory requirements, unconventional MV and adjunct therapy, the mortality rate remained high.