Rosen & Barkin's 5-Minute Emergency Medicine Consult (650 page)

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Bradydysrhythmia

CODES

427.81 Sinoatrial node dysfunction

BASICS

• Sickle cell disease (SCD) is an autosomal recessive hemoglobinopathy characterized by abnormal hemoglobin (HbS) which polymerizes under stress and deforms RBCs, resulting in hemolysis, vaso-occlusion, and subsequent tissue ischemia/infarction
  
• HbS production secondary to a single amino acid substitution in hemoglobin gene
  
• Occurs in people of African, Mediterranean, Middle Eastern, and Asian descent; areas where malaria is endemic
  
• Severity variable even among the same phenotype
  
• Genotypes and severity in African Americans:
  
  • HbSS, severe
    
  • HbSC, mild to moderate severity
    
  • HbSβ
    -
    thalassemia, mild to moderate severity
    
  • HbAS, sickle cell trait:
    
    • No manifestation of disease
      
    • At risk for sudden death with extreme physical exertion, severe hypoxia, severe dehydration, or maternal labor
      
• Chronic hemolytic anemia associated with progressive vasculopathy manifested by systemic and pulmonary hypertension, cholelithiasis, cutaneous leg ulcers, and priapism
  
• Acute vaso-occlusive crisis (VOC) can occur in essentially any organ systems:
  
  • Bone/joint crises:
    
    • Vaso-occlusion of bone microvasculature causes infarction
      
    • Long bones, ribs, sternum, spine, and pelvis affected
      
    • Dactylitis, or “hand–foot syndrome,” occurs at ages 6–24 mo
      
  • Acute chest syndrome:
    
    • Vaso-occlusion of pulmonary vasculature
      
    • Fat embolism from infarcted bone marrow and/or infections (viral or bacterial) may contribute
      
    • Associated
      Chlamydia pneumoniae and Mycoplasma pneumoniae
      isolated in sputum and
      Streptococcus pneumoniae
      bacteremia
      
    • High mortality (2–14%)
      
    • 50% of sickle cell patients will experience at least 1 episode
      
    • Radiographic pulmonary infiltrate with fever and respiratory symptoms makes it difficult to distinguish from pneumonia
      
    • More common in children
      
  • Splenic sequestration:
    
    • Splenic sinusoids become congested with sickled RBCs, obstructing outflow
      
    • Estimated 6–17% of SCD deaths
      
    • Circulatory collapse may be rapidly fatal
      
    • More common in children <5 yr old
      
  • Aplastic crisis:
    
    • Bone marrow suppression usually occurs secondary to viral infection, most commonly Parvovirus B19
      
    • Hallmark acute anemia with low reticulocyte count
      
    • Acute bone marrow suppression significantly worsens chronic anemia
      
    • Generally self-limited
      
    • More common in children
      
  • Cerebrovascular accident/transient ischemic attack (CVA/TIA):
    
    • Secondary to vaso-occlusion by sickled cells and thromboembolism in children and older patients, respectively
      
    • Children with SCD have a 300-fold increased risk of CVA/TIA
      
    • Most events occur before the age of 10 and after the age of 29 yr
      
  • Bacterial infection:
    
    • Sepsis is the leading cause of death in patients with SCD
      
    • Increased risk of bacteremia, meningitis, and osteomyelitis
      
    • Impaired splenic function impairs ability to fight encapsulated organisms
      
    • S. pneumoniae, Haemophilus influenzae, Staphylococcus aureus, Escherichia coli,
      and
      Salmonella
      are leading organisms
      
    • Children <5 yr of age have 400-fold increase in pneumococcal infections.
      
  • Priapism:
    
    • Painful, sustained, unwanted erection >3 hr
      
    • More commonly low-flow (ischemic) priapism than high-flow (nonischemic)
      

• Acute sickle cell complications in children carry high morbidity and should be screened for aggressively
  
• Infections commonly precipitate crisis
  
• Confirm immunization history (pneumococcal and
  H. influenzae
  type b)
  
• Determine if child is receiving prophylactic penicillin, normally indicated in children ≤5 yr old
  
• Overwhelming infection highest in children <3 yr of age
  

• Variable frequency of crisis episodes, not uncommon for increased frequency
  
• Anemia is more profound
  
• Increased rates of hypertensive disorders of pregnancy, asymptomatic bacterial infections, UTI, and pyelonephritis leading to septicemia
  
• Increased risk of spontaneous abortions, antepartum bleeding, and premature rupture of membranes
  
• Increased risk of preterm labor, intrauterine growth restriction, and low birth weight
  

Common crisis precipitants:

• Infection (bacterial and viral)
  
• Dehydration
  
• Hypoxemia
  
• Acidosis
  
• Emotional stress
  
• Surgery/trauma
  
• Weather changes
  
• Pregnancy
  
• Toxins
  

DIAGNOSIS

• May present with either:
  
  • Pain crisis
    
  • Complications of the disease
    
  • Combination of above
    
• May not demonstrate usually autonomic signs of acute pain
  
• Sickle cell pain crisis:
  
  • Bone/joint crisis:
    
    • Pain in extremities, back, sternum, or joints
      
    • Variable extremity and joint swelling/warmth
      
    • Hand–foot syndrome in infants; swelling in hands and feet and a reluctance to walk or use hands
      
  • Abdominal crisis:
    
    • Abdominal pain without peritonitis
      
    • Variable nausea, vomiting, diarrhea
      
  • Priapism: Prolonged painful erection
    
• Complications/progression of disease:
  
  • Acute chest syndrome:
    
    • Chest pain
      
    • Fever
      
    • New pulmonary infiltrates on chest radiographs
      
    • Respiratory symptoms
      
    • Hypoxemia
      
  • Splenic sequestration crisis:
    
    • Abdominal pain, splenomegaly
      
    • Fatigue, lethargy, pallor
      
    • Hypotension, tachycardia, syncope, shock
      
  • Aplastic crisis:
    
    • Variable fever, headache, nausea, vomiting
      
    • Fatigue, pallor, tachycardia
      
  • CVA/TIA:
    
    • Focal neurologic deficit
      
    • Mental status changes
      
    • Seizure
      

• Genotype
  
• Onset of current symptoms
  
• Previous crises
  
• Immunizations
  
• Surgical history
  
• Determine typical vs. atypical crisis
  

Conduct a thorough physical exam:

• Vital signs: BP, HR, temperature, O
  ₂
  saturation
  
• General appearance: Jaundice, pallor
  
• Cardiopulmonary exam:
  
  • Rales, wheezing, tachypnea
    
  • Peripheral edema, elevated JVD
    
  • Gallops, murmurs
    
• Abdominal exam:
  
  • Organomegaly, tenderness, peritonitis
    
• Musculoskeletal exam
  
  • Erythema on extremities
    
  • Warm, swollen hands and feet in children
    
• Neurologic exam:
  
  • Focal neurologic impairment
    
  • Cranial nerve palsy
    

Conduct a thorough physical exam, with focus on signs of infection or ischemia.

• CBC:
  
  • Compare Hb with prior values if available
    
  • Leukocytosis is common and does not necessarily indicate infection
    
• Reticulocyte count is generally elevated in SCD individuals, and decreased with aplastic crisis
  
• Complete metabolic panel (CMP):
  
  • Be aware that creatinine may appear normal despite baseline chronic renal dysfunction
    
  • Elevated total bilirubin levels may indicate intravascular hemolysis
    
• Markers of hemolysis (total bilirubin, haptoglobin, and LDH) may be present at variable degrees
  
• Serial arterial blood gases and A–a gradients helpful in acute chest syndrome
  
• Cultures: Blood, urine, throat, and CSF (if indicated)
  
• Type and screen (or cross)
  
• Urine pregnancy test in women
  

• Radiographs should be directed to confirm diagnosis:
  
  • Chest radiograph if pneumonia or acute chest syndrome suspected
    
  • Extremity radiographs if osteomyelitis suspected
    
• IV contrast may exacerbate or precipitate a crisis
  
• Head CT/MRI to evaluate stroke