.... Imaging

Several imaging modalities can aid in the diagnosis of

severe sequela of vasoocclusive crises. When fever or res piratory signs or symptoms are present, a c hest x-ray should

be obtained to assess for signs of infection or infarction.

Should pulmonary embolus be suspected, a helical con ­

trast computed tomography (CT) can be performed.

Patients with significant abdominal pain should undergo

abdominal imaging to search for evidence of gallbladder or

liver infarction or infection. Patients with new neurologic

symptoms or signs should have a CT scan of the brain to

assess for possible CVA.

PROCEDURES

An exchange transfusion is used to reduce vasoocclusion;

the abnormal Hb is removed and replaced with normal

donor blood. It is used during certain crises s uch as stroke

and priapism when the hematocrit is greater than 35%. The

procedure involves removing 500 mL (adult) through one

intravenous (IV) line while simultaneously infusing 500 mL

of normal saline (NS) through a second. After blood is

removed the patient is given one unit of donor blood.

MEDICAL DECISION MAKING

The differential diagnosis associated with sickle cell vasaocclusive crisis is broad. It includes acute chest, pneumonia,

pulmonary embolism (PE), myocardial infarction (MI),

cellulitis, osteomyelitis, and septic arthritis. The clinician

must differentiate a simple pain crisis from one of these

potential life threats. A high level of suspicion must be

maintained in each case.

Bone and joint pain during a pain crisis does not usually

present with limited range of motion. When joint range of

motion deficits are present, the physician should be prompted

to search for osteomyelitis or septic arthritis. Although an

elevated WBC may be typical of a sickle cell pain crisis, a left

shift would be more concerning for infection and necessitates

a closer evaluation for an infectious process. A high index of

suspicion for infection is always warranted. Localized left

upper quadrant pain could indicate splenic infarction,

whereas right upper quadrant pain may indicate cholecysti ­

tis. Electrocardiogram (ECG) findings consistent with acute

MI or ischemia (ST-segment elevation, hyperacute T waves,

T-wave inversions, ST-segment depression) should prompt

further cardiac evaluation. Patients whose chest pain is

atypical for their pain crisis and who also exhibit vital sign

abnormalities or signs of right heart strain on the ECG

should be evaluated for PE. Patients with altered mental status should be evaluated for severe anemia due to splenic

sequestration, meningitis, CVA/transient ischemic attack

(TIA), or seizure disorder (Figure 71-1).

TREATMENT

Any identifiable preCipitants of pain crisis should be

treated. Even if the patient does not appear dehydrated,

fluids should be replaced. If unable to tolerate oral fluids,

5% dextrose with 0.45% NS is the fluid of choice for fluid

replacement. NS boluses are reserved for the hypovolemic

patient. A simple blood transfusion is indicated in patients

with symptomatic anemia, sequestration crisis, hemolysis,

or aplastic crisis. Exchange transfusion should be considered in severe vaso-occlusive crises such as acute chest

syndrome, stroke, or priapism, where the Hgb level is > 10.

..... Pain Crises

Treatment should begin with prompt analgesic administration. Supplemental oxygen is needed only for patients with

low oxygen saturations or those with oxygen saturations

lower than baseline. Mild pain should be treated with 1 g of

acetaminophen by mouth (PO) every 4 hours (children: 15

mg/kg/dose PO), codeine 0.5-1 mg/kg/dose PO, or ibuprofen 800 mg (children: 5-10 mg/kg/dose) PO every 8 hours.

IV or intramuscular ketorolac has been shown to be effective with limitations in dosing frequency. Opiates are firstline therapy for a moderate to severe pain crisis. Morphine

(0.1-0.15 mg/kg/dose) and hydromorphone (0.0 1-0.02

mg/kg/dose) are appropriate opiates to consider.

Diphenhydramine is often required to blunt histamineinduced pruritus resulting from opiate administration .

.... Infection

Antibiotics should be used for patients with suspected

infection ( eg, those with suspected meningitis, urinary

tract infection, acute chest syndrome, or osteomyelitis).

.... Anemia

Transfusion should be considered for symptomatic anemia

and is generally indicated in cases in which the hemoglobin

CHAPTER 71

CT head: CVA?

Figure 71-1. Sickle cell emergencies diagnostic algorithm. CP, chest pain;

CT, computed tomography; CTA, computed tomography angiography; CVA,

cerebrovascular accident; CXR, chest x-ray; ECG, electrocardiogram.

is <6 gldL with an inappropriately low reticulocyte count.

An acute crisis (acute chest, stroke, liver/gall bladder

infarction, priapism) with hemoglobin <10 g/dL also merits transfusion. With regard to aplastic crisis, simple transfusion is often sufficient. Splenic sequestration is best

treated with adequate hydration, analgesia, and simple

transfusion. Refractory cases are treated with exchange

transfusion.

..... Acute Chest Syndrome

Control pain, hydrate, and start oxygen therapy. Give

empiric antibiotics consisting of a third-generation cephalosporin and a macrolide (eg, ceftriaxone and azithromycin). Triggers for transfusion should include a Pa02 <70

mmHg or an oxygen saturation that falls > 10% from their

baseline.

..... Stroke

Patients with stroke related to SCD are not considered

candidates for thrombolysis. Correction of hypovolemia,

hypoxia, hypoglycemia, and fever are necessary. Exchange

transfusion should be performed in an effort to reduce the

percent of HbS to <30%. Hemorrhagic strokes warrant

neurosurgical consultation.

..... Priapism

Hydrate, treat pain, and transfuse (refractory cases). After

4-6 hours of priapism and failure of ice packing, drainage

may be necessary. Drainage should be done in conjunction

with urologic consultation .

DISPOSITION

..... Admission

Criteria for admission include refractory pain, acute chest

syndrome, CVA or TIA, unexplained fever >38.3°C or focal

infection, aplastic crisis, splenic sequestration, or refractory priapism .

..... Discharge

If the patient's pain is well controlled and good outpatient

follow-up is available, he or she may be discharged.

SICKLE CELL EMERGENCIES

SUGGESTED READING

Baker M, Hafner JW. What is the best pharmacologic treatment

for sickle cell disease in pain crises? Ann Emerg Med.

201 2;59:515-5 16.

Claudius I. Sickle cell disease. In: Tintinalli JE, Stapczynski JS,

Ma OJ, Cline DM, Cydulka RK, Meckler GD. Tintinalli's

Emergency Medicine: A Comprehensive Study Guide. 7th ed.

New York, NY: McGraw-Hill, 201 1: 1 480-1 488.

Gladwin MT, Vichinsky E. Pulmonary complications of sickle

cell disease. N Engl ] Med. 2008;359, 2254-2265.

Kavanagh PL, Sprinz PG, Vinci SR, et a!. Management of children with sickle cell disease: A comprehensive review of the

literature. Pediatrics 20 11;128:1 552.

Rees DC, Williams TN, Gladwin MT. Sickle-cell disease. Lancet

201 2;376, 201 8-203 1.

Roberts JR, Hedges JR. Clinical Procedures in Emergency

Medicine. 5th ed. Philadelphia, PA: Saunders, 2009.

Transfusion Reactions

Christopher Reverte, MD

jorge Fernandez, MD

Key Points

• Obtain consent when possible before admin istering

blood transfusions and properly inform patients

regarding the risk of developing complications.

• Always transfuse leukocyte-reduced blood products to

recipients who are immunocompromised to prevent

graft versus host disease.

• It may be difficult to clinically distinguish between

benign (urticaria, simple febrile reactions) and more

INTRODUCTION

Emergency transfusion of blood products is often necessary

in the emergency department (ED) for life-threatening

illness or injuries. Commonly transfused blood products

include packed red blood cells (PRBCs), platelets, freshfrozen plasma (FFP), and cryoprecipitate. In the United

States, approximately 30 million units of blood components

are transfused annually. Approximately 1% of patients

receiving transfusions will develop a transfusion-related

reaction, the most common being a simple febrile reaction.

Transfusion reactions must be rapidly identified to prevent

morbidity and mortality.

Acute intravascular hemolysis is due to ABO blood

group incompatibility between the donor and recipient.

Preformed antibodies in the patient's serum react with

antigens on the transfused PRBCs, resulting in complement-mediated intravascular RBC lysis. Patients present

with chest pain, shortness of breath, back pain, fever,

tachycardia, or shock. Complications include acute renal

failure, disseminated intravascular coagulopathy (DIC),

cardiovascular collapse, and death.

Delayed extravascular hemolysis is due to non-ABO blood

group incompatibility between the donor and recipient.

serious transfusion reactions (acute hemolysis,

anaphylaxis, transfusion-associated acute lung injury,

sepsis).

• Whenever a transfusion reaction is suspected,

immediately stop the transfusion, confirm that the

correct blood product was administered to the correct

recipient, and send samples of the transfused product

and the recipient's serum to the blood bank for further

ana lysis.

This type of hemolysis is the result of splenic removal of

RBCs, which may present days to weeks after the transfusion

and in general is not life-threatening.

Simple febrile reaction is the most common type of

transfusion-related reaction, occurring in about 1-7% of

all transfusions. It is caused by recipient antibodies to

donor leukocytes. The risk is minimized by leukoreduction.

Patients present with fever without urticaria, bronchospasm,

or shock.

Type I hypersensitivity reactions include urticaria and

anaphylaxis. Urticaria is the result of a mild reaction due to

recipient antibodies to donor blood. Patients present with

hives and pruritus without fever, bronchospasm, or shock.

Anaphylaxis is a life-threatening reaction seen most com ­

manly in immunoglobulin A (IgA)-deficient individuals who

are transfused IgA-containing blood. Patients rapidly develop

fever, airway obstruction, bronchospasm, urticaria, and/or

shock.

Transfusion-associated acute lung injury (TRALI)

may result in a life-threatening noncardiogenic pulmonary

edema. It is associated with anti-HLA antibodies (higher

rates in pregnant donors). It most commonly occurs after

plasma transfusion but can occur from transfusion of any

type of plasma-containing blood product (including

304

TRANSFUSION REACTIONS

PRBC, platelets, cryoprecipitate, etc). Signs and symptoms

include fever, severe respiratory distress, noncardiogenic

pulmonary edema and cardiovascular collapse.