Hemophagocytic Lymphohistiocytosis and Other Culture Negative Sepsis-Like Syndromes in the ICU

There are many sepsis-like inflammatory syndromes that may be encountered by critical care practitioners. Clinically, these syndromes may imitate sepsis and are often identified after an extensive, but unrevealing evaluation for infection. In some instances, these syndromes are anticipated complications of advanced therapies for malignancy. It is vitally important to identify these disorders and treat them with specific chemotherapeutic or immunomodulating therapies. This chapter will focus on hemophagocytic lympho-histiocytosis (HLH), a rare disorder of pathologic immune system activation that presents as a sepsis-like illness in the critically ill. While treatment of HLH with chemotherapy and immunosuppression should be guided by an expert hematologist, the diagnosis is often made by the critical care medicine practitioner. We present a case illustrating the challenges of defining this syndrome in a patient with recurrent critical illness, and review the evidence underlying diagnostic and prognostic criteria for this protean syndrome. We also review several of the more common sepsis-like inflammatory syndromes that are encountered in the critical care unit along with their specific treatments.