Rosen & Barkin's 5-Minute Emergency Medicine Consult (269 page)

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Hip Injury

CODES

• 820.22 Closed fracture of subtrochanteric section of neck of femur
  
• 821.00 Closed fracture of unspecified part of femur
  
• 821.01 Closed fracture of shaft of femur
  

BASICS

• Fever is an elevation of core body temperature caused by an increase in the body’s thermoregulatory set point.
  
• Prostaglandin E2 (PGE2) synthesis in the anterior hypothalamus controls the thermostat, and is the target of antipyretics.
  
• Core temperature is regulated to 37°C ± 2°C.
  
• Autonomic discharge from hypothalamus can raise core temperature through shivering and dermal vasoconstriction.
  
• Normal circadian variation in core temperature occurs with nadir in early morning and peaks in late afternoon.
  
• Fever is not synonymous with hyperthermia or hyperpyrexia.
  
• Hyperthermia is an elevated temperature with normal thermostat set point; caused by excessive endogenous heat production or endogenous production (e.g., malignant hyperthermia or heat stroke).
  
• Hyperpyrexia is extreme fever >41.5°C usually from CNS hemorrhages.
  
• Both exogenous and endogenous factors can raise the body’s set thermoregulatory point:
  
  • Endogenous pyrogens include PGE2, IL-1, IL-6, TNF, IFN-γ.
    
  • Exogenous pyrogens include lipopolysaccharide (LPS) endotoxin and other TLR ligands, and toxic shock syndrome toxin (TSST-1) and other MHC II ligands.
    
• Patients on anticytokine medications or glucocorticoids have impaired fever response.
  
• Fever of unknown origin (FUO):
  
  • Fever >38.3°C for at least 3 wk as an outpatient and 3 days of inpatient evaluation or 3 outpatient visits without determining etiology.
    

• Infectious processes:
  
  • CNS, chest and lung, gastrointestinal, genitourinary, skin, soft tissue and bone, vascular and endocardial
    
  • Iatrogenic: Catheters, implants, hardware, recent surgical sites.
    
• 1° CNS processes such as CVA, trauma, seizures
  
• Neoplastic fevers
  
• Drug fever:
  
  • Most drugs can cause elevated temperatures by a wide variety of mechanisms
    
  • Toxidromes (e.g., adrenergic, anticholinergic, dopaminergic, salicylate overdose, serotonin toxicity)
    
  • Hypersensitivity:
    
    • Allergic reaction
      
    • Serum sickness
      
  • Jarisch–Herxheimer reaction
    
  • Local phlebitis from irritant drugs
    
• Severe withdrawal:
  
  • Alcohol
    
  • Benzodiazepines
    
• Systemic rheumatologic and inflammatory diseases (e.g., familial Mediterranean fever, rheumatoid arthritis, sarcoidosis, systemic lupus erythematosus, temporal arteritis)
  
• Endocrine:
  
  • Hyperthyroidism, pheochromocytoma
    
• Miscellaneous:
  
  • Alcoholic cirrhosis
    
  • Acute inhalation exposures (e.g., metal fume fever)
    
  • Cotton fever:
    
    • Febrile reaction from an injected contaminant when IV drug abusers strain drug through cotton
      
  • Sickle cell disease
    
  • Hemolytic anemia
    
  • Pulmonary embolus
    
• Common causes of FUO:
  
  • Infectious:
    
    • Abdominal and pelvic abscesses
      
    • Cardiac (endocarditis, pericarditis)
      
    • Cat scratch disease
      
    • Cytomegalovirus
      
    • Epstein–Barr virus
      
    • TB (miliary, renal, or meningitic)
      
    • Typhoid enteric fevers
      
    • Visceral leishmaniasis
      
  • Neoplastic:
    
    • Colon adenocarcinoma
      
    • Hepatocellular carcinoma and metastases
      
    • Myeloproliferative disorders
      
    • Leukemia and lymphoma
      
    • Renal cell carcinoma
      

DIAGNOSIS

• Chills, shivering, and rigors:
  
  • Rigors may suggest bacteremia
    
• Weight loss:
  
  • Suggestive of neoplastic, chronic infectious, or endocrine disorders
    
• Night sweats:
  
  • Suggestive of neoplastic, chronic inflammatory disease, or TB
    
• Specific fever patterns:
  
  • Daily morning temperature spikes:
    
    • Miliary TB, typhoid fever, polyarteritis nodosa
      
  • Relapsing fevers: Febrile episode with alternating afebrile intervals:
    
    • Seen in malaria,
      Borrelia
      infections, rat-bite fever, and lymphoma
      
  • Remittent fever: Temperature falls daily but does not return to normal:
    
    • Seen in TB and viral diseases
      
  • Intermittent fevers: Exaggerated circadian rhythm:
    
    • Seen in systemic infections, malignancy, and drug fever
      
  • Double quotidian fever:
    
    • Common pattern of 2 temperature spikes in 24 hr
      
    • In FUO, consider miliary TB, visceral leishmaniasis, and malarial infections
      
• High-risk features:
  
  • Anticytokine therapy (e.g., TNF-α monoclonal antibodies, calcineurin inhibitors)
    
  • Glucocorticoid use
    
  • Immunosuppressed states
    
  • Incomplete vaccination status
    
  • IV drug use
    
  • Pregnancy and peripartum patients
    
  • Rash
    
  • Recent chemotherapy
    
  • Recent travel
    
  • Splenectomy
    

• Elevated core temperature:
  
  • Temperature >38°C (100.4°F) rectally or 37.5°C (99.5°F) orally
    
  • Lower thresholds in patients older than 65 yr, as the febrile response is not as strong
    
• Diaphoresis:
  
  • Absence of diaphoresis with severe hyperthermia suggests anticholinergic poisoning or heat stroke.
    
• Tachycardia:
  
  • For each degree of elevation in temperature in Fahrenheit, there should be a 10 bpm increase in pulse.
    
  • Relative bradycardia (Faget sign):
    
    • Associated with malaria, typhoid fever, CNS disorders, lymphoma, drug fever, brucellosis, ornithosis, Legionnaire disease, Lyme disease, and factitious fevers
      
• Muscle rigidity, clonus, and hyper-reflexia:
  
  • Associated with specific toxidromes and medical conditions
    
• Changes in mental status:
  
  • Toxic–metabolic encephalopathy vs. primary CNS disorder
    
• Rash:
  
  • Lesion type, distribution, and progression can offer important clues to diagnosis.
    
  • Petechia, purpura, vesicles, mucosal, or palm and sole involvement require special note
    
• Signs of hyperthyroidism:
  
  • Goiter
    
  • Exophthalmos
    

• Core temperature is most acutely measured rectally.
  
• Careful history and physical exam (PE) necessary to determine need for further diagnostic testing:
  
  • History should elicit any sick contacts, previous infections, occupational exposures, recent travel, medications, animal or tick exposure, and immunization status.
    

• CBC:
  
  • Important in determining neutropenia in patients with risk factors
    
  • Neutrophilia and bandemia suggestive of bacterial infection
    
  • Lymphocytosis suggestive of typhoid, TB, brucellosis, and viral disease
    
  • Atypical lymphocytosis seen in mononucleosis, cytomegalovirus, HIV, rubella, varicella, measles, and viral hepatitis
    
  • Monocytosis suggestive of TB, brucellosis, viral illness, and lymphoma
    
• Lactate:
  
  • Initial and repeat measurements useful for screening for sepsis, risk stratification, and management decisions
    
• Urinalysis and urine culture
  
• Blood cultures:
  
  • Obtain for all systemically ill patients, and patients at risk for bacteremia
    
• Thick and thin blood smears and malaria antigen testing in at-risk individuals for parasitic and intraerythrocytic infections
  
• Stool culture and
  Clostridium difficile
  assay for suspected individuals.
  
• Heterophile antibody testing in select patients.
  
• Erythrocyte sedimentation rate and C-reactive protein generally not useful:
  
  • Very high values suggestive of endocarditis, osteomyelitis, TB, and rheumatologic conditions.