Experiences of the Department of Anesthesiology and Intensive Therapy of Semmelweis University during the 2009 pandemic H1N1 (pH1N1) influenza outbreak

Abstract

Abstract Introduction: The 2009 pandemic 2009 H1N1 (pH1N1) influenza A virus shows a markedly different disease pattern than seasonal strains, causing critical illness in relatively young, female, pregnant individuals as well as in comorbid patients. Materials and methods: The Department of Anesthesiology and Intensive Therapy of Semmelweis University served as a regional influenza center for the adult critically ill during the winter of pH1N1 outbreak. We analyzed data collected from 26 suspected pH1N1 critically ill patients treated in our unit during this period. Results: Sixteen cases were confirmed as pH1N1 infection with RT-PCR, while the other 10 patients with influenza like illness showed tendency to a different age and comorbidity, as well as outcome characteristics, suggesting a different pathogenesis. Confirmed pH1N1 patients showed a mean age of 50.5 years (median: 44; range: 20–85), with female predominancy (69%). Comorbidity was present in 69% of cases (chronic heart conditions, chronic pulmonary disease, previous history of malignancy present in 31; 25 and 19%, respectively). Twenty-five percent of the patients were pregnant women. Nineteen percent of the cases received previous pH1N1 vaccination. But two patients were later readmitted for worsening chronic conditions that led to death, which resulted in a total mortality rate of 31%. Mean APACHE II and SOFA scores on admittance were 12.2 and 5.3, respectively. Average length of treatment was 11.5 days (median: 6.5; range 2–50 days). All patients received ventilatory assistance, 69% of patients received invasive, while 31% of patients received non-invasive ventilatory assistance. The average number of days of invasive ventilation was 10.5 days (median: 5.5; range: 2–45). Forty-five percent of ventilated patients required rescue ARDS therapy. Complications included hemodynamic instability (56%); acute renal failure (13%) and pneumothorax (13%). Superinfection with other microbes were observed in 56% of the patients. Conclusions: In our study, pH1N1 infected critically ill patients had a wide age range, but were more commonly female, pregnant, or had a previously described underlying disease. Mortality, length of treatment, need for invasive mechanical ventilation, length of mechanical ventilation, major complication rates were similar to those previously described. A previously not reported relatively high occurrence of pneumothorax was noted, which is possibly a long-term complication of severe viral pneumonitis.