One major problem of jet ventilation is CO 2 clearance due to very low V t . There are two options in resolving this problem. The simplest approach is to establish spontaneous breathing. However, patients might be sedated and therefore need superimposed CPAP/ASB to improve tidal inflation until sedation is adapted. In the case of severe hypercapnia, the use of Interventional Lung Assist (ILA) can improve CO 2 clearance. We observed a high mortality rate, which can be -explained, in part, by patient selection. All of our patients presented in this report were admitted with fixed hypoxemia despite optimized conventional ventilation. Two patients presented a prolonged period of hypoxemia and mechanical ventilation before admission. One of these patients was already on mechanical ventilation 14 days due to septic CMV-colitis and Pneumocystis jiroveci pneumonia with poor prognosis. The other patient was admitted to our ICU after a prolonged period of severe hypoxemia and septic shock with hypoperfusion. All five patients had a HSV-PCR-positive BAL, confirmed via lung biopsy in one patient. Viral coinfection with HSV may cause and prolongs a status of persistent immunosuppression during severe H1N1 infection, which is associated with a high risk of death. This hypothesis is supported by findings of Monsalvo and colleagues, who found pathogenic immune complexes as previously unknown biological mechanism for the unusual age distribution of severe H1N1 infections [11] .