Characteristics and outcomes of critically ill patients with influenza A (H1N1) in the Western Balkans during the 2019 post-pandemic season

Background: This study looked at the characteristics and outcomes of critically ill patients with confirmed influenza A (H1N1) pdm09 infection in the Western Balkans in the post-pandemic period. Materials and Methods: This retrospective observational study of medical records and associated data collected during the post-pandemic period included all mechanically ventilated adult patients of two university-affiliated hospitals of the Western Balkans between 1 January and 31 March 2019 who had influenza A (H1N1) pdm09 infection confirmed by real-time reverse transcriptase-polymerase chain reaction from nasopharyngeal swab specimens and respiratory secretions. Results: The study included 89 patients, 49 males (55.1%), aged 56.09 +/- 12.64 years. The median time from shift from hospital time to intensive care unit was 1 day (range: 1-2). In the post-pandemic period, cases observed in this study were found to have the following comorbidities: cardiovascular diseases in 44 (49.4%) patients and diabetes in 21 (23.6%) patients. Thirty-one patients (34.8%) in this study were obese. All 89 patients (100%) experienced some degree of acute respiratory distress syndrome, and 39 (44%) had multiorgan failure. Eighty-three patients (93%) were intubated and mechanically ventilated, 6 (7%) received non-invasive mechanical ventilation, 12 (13%) were treated with vvECMO and 36 (40%) received renal replacement therapy. Vasoactive support was needed by 56 (63%) patients. The median duration of mechanical ventilation was 9 (6-15.5) days. The hospital mortality rate was 44%. Conclusion: Critically ill patients with confirmed influenza A (H1N1) pdm09 infection in the post-pandemic season were older, required vasoactive drugs more often, and there was a trend of higher survival compared to H1N1 infection patients in the previous pandemic seasons.