MHC class I (H-2D b ) pentamers presenting the selected peptide MV-H 22-30 (D b MV-H 22-30 -pentamers) were ordered from ProImmune Ltd (Oxford, UK). Cells were washed with FACS buffer and stained with 5 mL pentamer-solution diluted in 100 ml FACS buffer at 4uC for 30 min. After one washing step the cells were analyzed using the FACSCalibur. MV-specific cells were gated as CD8 + and CD19-negative lymphocytes to exclude pentamer + CD19 + cells. Superimposed high-frequency jet ventilation combined with continuous positive airway pressure/assisted spontaneous breathing improves oxygenation in patients with H1N1-associated ARDS BACKGROUND: Numerous cases of swine-origin 2009 H1N1 influenza A virus (H1N1)-associated acute respiratory distress syndrome (ARDS) bridged by extracorporeal membrane oxygenation (ECMO) therapy have been reported; however, complication rates are high. We present our experience with H1N1-associated ARDS and successful bridging of lung function using superimposed high-frequency jet ventilation (SHFJV) in combination with continuous positive airway pressure/assisted spontaneous breathing (CPAP/ASB). METHODS: We admitted five patients with H1N1 infection and ARDS to our intensive care unit. Although all patients required pure oxygen and controlled ventilation, oxygenation was insufficient. We applied SHFJV/CPAP/ASB to improve oxygenation. RESULTS: Initial PaO(2)/FiO(2 )ratio prior SHFJV was 58-79 mmHg. In all patients, successful oxygenation was achieved by SHFJV (PaO(2)/FiO(2 )ratio 105-306 mmHg within 24 h). Spontaneous breathing was set during first hours after admission. SHFJV could be stopped after 39, 40, 72, 100, or 240 h. Concomitant pulmonary herpes simplex virus (HSV) infection was observed in all patients. Two patients were successfully discharged. The other three patients relapsed and died within 7 weeks mainly due to combined HSV infection and in two cases reoccurring H1N1 infection. CONCLUSIONS: SHFJV represents an alternative to bridge lung function successfully and improve oxygenation in the critically ill. The swine-origin 2009 H1N1 influenza A virus has become the predominant influenza virus worldwide since its identification. H1N1 influenza might cause acute respiratory distress syndrome (ARDS) and potentially result in extracorporeal membrane oxygenation (ECMO) therapy [1] . Experience from Australia and New Zealand describes an incidence of mechanical ventilation in 64.6% of H1N1 patients and 11.6% ECMO (with a mortality of approximately 21%) treated within the intensive care unit (ICU) [2] .