Diminished intestinal IL-13 production is present in UC patients and wanes further with clinical disease progression. These findings suggest that UC patients may be differentiated from CD patients by intestinal IL-13 quantitation, and UC patients may benefit from IL-13 enhancing therapies.

Cardiac abnormalities seen in patients with subarachnoid hemorrhage (SAH) are considered to be a neurally mediated process rather than a manifestation of coronary artery disease. In patients with SAH, myocardial injury evidenced by troponin elevation appears to predict short and long-term outcomes independently of other conventional risk. Although incidence of electrocardiographic changes, arrhythmias and left ventricular systolic dysfunction do not independently predict the outcomes, monitoring these changes and optimizing hemodynamic status in high-grade SAH is crucial to ensure adequate cerebral perfusion and arterial oxygenation. Novel interventions that go beyond blood pressure control, prevention of re-bleeding, and aneurysm obliteration should target early physiologic derangements seen in the acute phase of SAH. The early resuscitation phase in SAH represents the greatest opportunity for impacting clinical outcome and is thus the most promising window of opportunity to demonstrate a benefit when investigating novel therapeutic strategies related to protection and modulation of cardiovascular function. Specific measures, such as the early use of beta-adrenergic antagonists, to prevent these cardiac abnormalities and ameliorate its impact on morbidity and mortality are yet to be established.

Please cite this paper as: Kennedy et al. for the 2009 Pandemic H1N1 Influenza‐Associated Lower Respiratory Tract Hemorrhage Working Group. (2012) Lower respiratory tract hemorrhage associated with 2009 pandemic influenza A (H1N1) virus infection. Influenza and Other Respiratory Viruses DOI: 10.1111/irv.12022. Background  Influenza‐associated lower respiratory tract hemorrhage (LRTH) has been reported in previous pandemics and is a rare complication of seasonal influenza virus infection. We describe patients with LRTH associated with 2009 pandemic influenza A (H1N1) (pH1N1) virus infection identified from April 2009 to April 2010 in the United States. Methods  We ascertained patients with pH1N1‐associated LRTH through state and local surveillance, the Emerging Infections Program, and CDCs Infectious Diseases Pathology Branch. All patients had influenza A, evidence of pneumonia, and evidence of LRTH. Results  We identified 44 cases; the median number of days from illness onset to clinical signs of LRTH was one. Hemoptysis or respiratory tract bleeding was documented in 40% of pH1N1‐associated LRTH cases, often present early during the course of illness. Twenty‐one (48%) patients with LRTH had no other hemorrhagic diatheses. Seven (23%) patients with LRTH received antiviral treatment within two days of illness onset. Conclusions  During influenza season, clinicians should consider influenza infection in the differential diagnosis for patients presenting with hemoptysis or other signs or symptoms of LRTH. While the impact of timing of antiviral therapy on this complication has not been studied, the rapid progression of LRTH may support use of early empiric therapy. Continued investigation is necessary to betterdefine the clinical spectrum of both seasonal influenza‐ and pH1N1‐associated LRTH.

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