Erythropoietin response in critically ill mechanically ventilated patients: a prospective observational study.

INTRODUCTION: Anemia is a common problem in critically ill patients. The etiology of anemia of critical illness is often determined to be multifactorial in the clinical setting, but the pathophysiology remains to be elucidated. Erythropoietin (EPO) is an endogenous glycoprotein hormone that serves as the primary stimulus for erythropoiesis. Recent evidence has demonstrated a blunted EPO response as a factor contributing to anemia of critical illness in specific subsets of patients. Critically ill patients requiring mechanical ventilation who exhibit anemia have not been the subject of previous studies. Our goal was to evaluate the erythropoietic response to anemia in the critically ill mechanically ventilated patient. METHODS: A prospective observational study was undertaken in the medical intensive care unit of a tertiary care, military hospital. Twenty patients admitted to the medical intensive care unit requiring mechanical ventilation for at least 72 hours were enrolled as study patients. EPO levels and complete blood count were measured 72 hours after admission and initiation of mechanical ventilation. Admission clinical and demographic data were recorded, and patients were followed for the duration of mechanical ventilation. Twenty patients diagnosed with iron deficiency anemia in the outpatient setting were enrolled as a control population. Control patients had baseline complete blood count and iron panel recorded by primary care physicians. EPO levels were measured at the time of enrollment in conjunction with complete blood count. RESULTS: The mean EPO level for the control population was 60.9 mU/ml. The mean EPO level in the mechanically ventilated patient group was 28.7 mU/ml, which was significantly less than in the control group (P = 0.035). The mean hemoglobin value was not significantly different between groups (10.6 g/dl in mechanically ventilated patients versus 10.2 g/dl in control patients; P > 0.05). CONCLUSION: Mechanically ventilated patients demonstrate a blunted EPO response to anemia. Further study of therapies directed at treating anemia of critical illness and evaluating its potential impact on mechanical ventilation outcomes and mortality is warranted.

Bronchiolitis obliterans organizing pneumonia in an orthotopic liver transplant patient.

A 67-year-old woman was hospitalized for progressive dyspnea on exertion. She had undergone orthotopic liver transplantation (OLT) 15 months before admission. Posttransplant therapy consisted of tacrolimus, trimethoprim/sulfamethoxazole, and prednisone (the latter two were discontinued after 1 year). Physical examination revealed fine bibasilar crackles. High-resolution chest CT demonstrated bilateral, diffuse, interstitial infiltrates. Symptoms persisted on i.v. antibiotics and bronchoscopy was performed demonstrating patchy fibroplastic plugs within air spaces consistent with bronchiolitis obliterans organizing pneumonia (BOOP). Prednisone was initiated and the patient had an uneventful recovery. BOOP was initially described as an idiopathic disease process with clinical, radiographic, pathological, and prognostic features distinguishing it from bronchiolitis obliterans and idiopathic pulmonary fibrosis. BOOP has been recognized as a complication of lung and bone marrow transplantation, but the mechanism is unknown. We report a case of BOOP after OLT to highlight the risk in all transplant patients as well as the protective effect of posttransplant prednisone.