Anemia is a common worldwide problem that is associated with nonspecific complaints. The initial focus for the emergency evaluation of anemia is to determine whether the problem is acute or chronic. Acute anemia is most commonly associated with blood loss, and the patient is usually symptomatic. Chronic anemia is usually well tolerated and is often discovered coincidentally. Once diagnosed, the etiology of anemia can often be determined by applying a systematic approach to its evaluation. The severity of the anemia impacts clinical outcomes, particularly in critically ill patients; however, the specific threshold to transfuse is uncertain. Evaluation of the current literature and clinical guidelines does not settle this controversy, but it does help clarify that a restrictive transfusion strategy (ie, for patients with a hemoglobin < 6-8 g/ dL) is associated with better outcomes than a more liberal transfusion strategy. Certain anemias may have well-defined treatment options (eg, sickle cell disease), but empiric use of nutritional supplements to treat anemia of uncertain etiology is discouraged.
Key words: anemia, transfusion, transfusion threshold, thalassemia
A 54-year-old Hispanic male presents to the ED with the complaints of fatigue and weakness. The weakness is described as generalized, and the symptoms have been present and constant for the last 2 days. The patient denies hematemesis, hematochezia, dark-colored stools, hematuria, or other evidence of bleeding. He also denies chest or abdominal pain, dyspnea, diaphoresis, fever, or chills. The patient has not seen a doctor in the last 15 years and does not think he has any medical conditions. The only medication he has been taking is over-the-counter ibuprofen, which he has been taking daily since he injured his back at work 2 weeks ago. The patient works as a construction laborer and denies past surgeries or allergies. His vital signs are: blood pressure, 110/50 mm Hg; heart rate, 127 beats/min; respirations, 22 breaths/min; and SpO2, 97% on room air. The patient is afebrile. His skin is warm and dry but, despite being dark-skinned, he appears a little pale. On eye examination, the sclerae appear to have a yellow hue. Cardiovascular examination reveals bounding pulses, a hyperdynamic precordium, and a grade II over VI soft, systolic murmur. The remainder of the examination is unremarkable, including a rectal examination, which is negative for occult blood. An ECG shows a sinus tachycardia but is otherwise normal. A basic chemistry panel is within normal limits; however, the CBC reveals a hemoglobin of 5.4 g/dL, hematocrit of 16%, WBC of 8000, and platelet count of 154,000. Based on the presenting symptoms and signs, the patient is likely to need RBC transfusions. An IV catheter is placed, and a normal saline infusion is initiated. A 500-mL bolus of normal saline reduces the heart rate to 105 beats/min. As you write the order for the transfusion, your nurse asks, “What is the goal for the transfusion and what is the cause of the anemia?” You think, “Good questions!”
In the next room, there is a 68-year-old male who reports 1 week of increasing weakness, dyspnea on exertion, and mild chest pressure. He states the reason for coming in today is that his chest pressure was substantially worse and was associated with diaphoresis. The patient has a history of atrial fibrillation (rate controlled) and has been taking dabigatran for the past 2 years. The patient denies hematemesis but has a history of dark stools. However, he states that he was placed on iron supplementation by his primary care physician over a year ago. He denies back pain, abdominal pain, fevers, chills, or focal neurological complaints. The patient has no known drug allergy and denies past surgeries, but he does have a history of hypertension and chronic anemia in addition to atrial fibrillation. Based on his chief complaints, an ECG, CBC, BMP, PT/INR, portable chest radiograph, and 325 mg of aspirin are ordered. His vital signs are: temperature, 37°C; blood pressure, 105/65 mm Hg; heart rate, 105 beats/min; respirations, 26 breaths/min; and SpO2, 94% on room air. Overall, the patient’s examination is unremarkable except for an irregularly irregular heart rate accompanied by a soft blowing systolic murmur, pale conjunctiva, and a positive fecal occult blood test on digital rectal examination. The patient’s ECG is consistent with rate-controlled atrial fibrillation and shows ST-segment depression in the lateral leads. The CBC reveals a hemoglobin of 4.9 g/ dL and a hematocrit of 15.2%, with a normal WBC and platelet count, PT, INR, and aPTT. His basic chemistry panel reveals an elevated BUN of 64 mg/dL and a creatinine of 2.3 mg/dL. The troponin is within the normal range. A normal saline bolus of 500 cc is administered. As you call cardiology, you wonder: what is the optimal treatment for this patient’s presentation… cardiac catheterization or transfusion?
Just as you think you are getting control of the ED, a 6-month-old boy is brought in by his parents for congestion, increased work of breathing, and perioral cyanosis. The parents state that their child is taking longer to feed because he seems to be out of breath. This has been going on for several weeks, and they are unsure if their child has had a fever; they do not have a thermometer or a pediatrician. The patient was born at home with a midwife. The child’s vital signs are: blood pressure, 70/50 mm Hg; heart rate, 155 beats/min; respiratory rate, 53 breaths/min; SpO2, 92% on room air. He is afebrile. On your examination, the child is alert and responsive, but he is small for his age. He cries at appropriate aspects of the physical examination and is easily consoled by his mother. He is tachypneic with bilateral faint rales but does not demonstrate retractions or nasal flaring. The patient’s face is dysmorphic. His skin has a yellow hue with scleral icterus and perioral cyanosis and acrocyanosis. On abdominal examination, he has significant hepatosplenomegaly. The rest of his physical exam is unremarkable. A basic chemistry panel is otherwise normal; however, his CBC reveals a hemoglobin of 7.8 g/dL, with a normal WBC and platelet count. The mean corpuscular volume is 75.4 fL, mean corpuscular hemoglobin concentration is 29.1%, and red cell distribution width is 16.2%. A chest radiograph is suggestive of pulmonary congestion. Pediatrics isn’t your strength, and you wonder: why is this child anemic, and what are my next steps?
Anemia is defined as an absolute decrease in the number of circulating red blood cells (RBCs). The diagnosis of anemia is based upon laboratory measurements of RBC indices that fall below accepted normal values. (See Table 1.) It is the most common hematologic disorder, and it is a global health problem. Worldwide, anemia affects 24.8% of the population and is more prevalent in children and pregnant women.1 The prevalence of anemia varies depending on the RBC indices used to define it. In the Americas, anemia affects 29% of preschool children and 24% of pregnant women.1 Another age group associated with an increased incidence of anemia is the elderly (defined as age ≥ 65 years). From a 2010 prospective population-based study of 8744 elderly individuals, the prevalence of anemia was 11%.2
Data on the frequency of anemia in the emergency department (ED) are less robust. Anemia occurs in 9% to 14% of pediatric ED patients and 14% of obstetric ED patients.3-5 Data defining the frequency of its occurrence in the general ED population is lacking. In emergency medicine, anemia is divided into 2 broad categories: acute, with potential lifethreatening complications; and chronic, with more stable clinical presentations. The focus of this issue of Emergency Medicine Practice is the ED evaluation of anemia and, more importantly, its management based on the best available evidence in the literature.
A literature search of PubMed was performed using the search terms anemia, transfusion, transfusion threshold, and emergency department. Studies within the last 12 years were analyzed and included reviews, case reports, case series, and prospective randomized trials. More than 300 articles were reviewed, and 57 were selected for inclusion in this issue. In addition, data from the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews were used. The literature, much of it observational in form, shows that hemoglobin levels < 6 g/dL, especially in acute anemia, are associated with worse outcomes compared to individuals with hemoglobin levels above this value. On the other hand, the literature has also shown that the use of RBC transfusions is associated with poor outcomes. Randomized controlled studies show that using a restrictive transfusion strategy (defined as a transfusion hemoglobin threshold of < 6-8 g/ dL) is associated with better outcomes than using a liberal strategy (defined as a transfusion hemoglobin threshold of < 9-10 g/dL). However, the hemoglobin level that should be the endpoint of transfusion therapy still has not been defined in the literature.
Evidence-based medicine requires a critical appraisal of the literature based upon study methodology and number of subjects. Not all references are equally robust. The findings of a large, prospective, randomized, and blinded trial should carry more weight than a case report.
To help the reader judge the strength of each reference, pertinent information about the study will be included in bold type following the reference, where available.
Timothy G. Janz, MD, FACEP, FCCP; Roy L. Johnson, MD, FAAEM; Scott D. Rubenstein, MD, MS, EMT-T
November 2, 2013