Rosen & Barkin's 5-Minute Emergency Medicine Consult (191 page)

Refer all patients with suspected or diagnosed DCS for hyperbaric therapy.

• Stable patients with mild symptoms may be discharged posthyperbaric oxygen treatment.
  
• Air travel may exacerbate symptoms as ambient pressure decreases.
  

Hyperbaric referral

• Difficult to distinguish musculoskeletal DCS from musculoskeletal pain
  
• Significant fatigue may be the only symptom of DCS
  
• Even minor symptoms or resolving symptoms suspected of being DCS should be treated with hyperbaric recompression therapy
  
• Do not delay recompression therapy for lab testing and imaging when DCS is most likely diagnosis
  
• Avoid in-water recompression therapy.
  

• Bennett MH, Lehm JP, Mitchell SJ, et al. Recompression and adjunctive therapy for decompression illness.
  Cochrane Database Syst Rev.
  2012;5:CD005277. doi:10.1002/14651858.CD005277.pub3.
  
• Divers Alert Network [Homepage]. Available at
  www.diversalertnetwork.org
  .
  
• Hawes J, Massey EW. Neurologic injuries from scuba diving.
  Neurol Clin.
  2008;26:297–308.
  
• Levett DZ, Millar IL. Bubble trouble: A review of diving physiology and disease.
  Postgrad Med J
  . 2008;84:571–578.
  
• Lynch JH, Bove AA. Diving medicine: A review of current evidence.
  J Am Board Fam Med
  . 2009;22:399–407.
  

See Also (Topic, Algorithm, Electronic Media Element)

• Arterial Gas Embolism
  
• Barotrauma
  
• Hyperbaric Oxygen Therapy
  

CODES

993.3 Caisson disease

BASICS

• A constant balance exists between intravascular clot formation and clot dissolution, clot forming when the former overpowers the latter.
  
• Clot can be superficial (to the fascia) or deep. The latter is called deep vein thrombosis (DVT).
  
• Pulmonary embolism (PE) and DVT are different ends of the clinical spectrum of the same disease process (venous thromboembolism, VTE).
  
• DVT can be upper or lower extremity, as well as distal or proximal (to the popliteal vein)
  
• Incidence is ∼2 1st time VTE episodes per 1,000 person yr.
  
• Prevalence increases with advancing age
  
• Common in both medical and surgical hospitalized patients
  
• Diagnosis is more accurate using active surveillance rather than clinical suspicion.
  

DVT in children is unusual, but when cases do occur, search for an underlying reason for hypercoagulability. Also, upper-extremity DVT is associated with central IV lines in children.

• Clot formation/dissolution is an intricately balanced system which can be influenced by many factors which must be considered
  
• Hypercoagulable states:
  
  • Cancer
    
  • Myeloproliferative disorders
    
  • Nephrotic syndrome
    
  • Sepsis
    
  • Inflammatory conditions:
    
    • Ulcerative colitis
      
  • Increased estrogen:
    
    • Pregnancy
      
    • Exogenous hormones (OCPs, HRT)
      
  • Antiphospholipid syndrome
    
  • Protein S, C, and antithrombin III deficiencies, factor V Leiden, prothrombin gene mutations, lupus, others
    
• Stasis:
  
  • Prolonged bed rest
    
  • Immobility (such as from a cast)
    
  • Long plane, car, or train rides
    
  • Neurologic disorders with paralysis
    
  • CHF
    
  • Obesity
    
• Vascular concerns/damage:
  
  • Trauma
    
  • Surgery
    
  • Anatomic anomalies (May–Thurner syndrome)
    
  • Central lines:
    
    • Especially with upper extremity DVT
      
• Multifactorial issues:
  
  • Advancing age
    
  • Medications (hydralazine, procainamide, phenothiazines)
    
  • Tobacco use
    
  • Prior DVT or PE
    
• Genetics:
  
  • Important with respect to some of the risk factors; ask about family history of clotting.
    
  • There is no consensus about which patients with VTE to test for inherited thrombophilias
    

Pregnancy is a risk factor for DVT, especially in the 3rd trimester up to the 2nd wk postpartum.

Age in and of itself is a risk for DVT (and PE). As with many diseases, the presentation may be atypical in the elderly.

DIAGNOSIS

• Leg swelling:
  
  • >1 cm difference is usually significant.
    
• Leg warmth and redness
  
• Leg pain and tenderness
  
• Palpable cord
  
• In superficial thrombophlebitis, a red pipe cleaner–like cord may be visible and palpable.
  
• Arm swelling, warmth, or tenderness:
  
  • Upper extremity or subclavian vein involved
    
• Phlegmasia cerulea dolens:
  
  • Cold, tender, swollen, and blue leg (secondary arterial insufficiency, venous gangrene)
    
• In phlegmasia alba dolens:
  
  • Cold, tender, and white leg (secondary arterial insufficiency)
    

• Determination of a patient’s clinical (pretest) risk is a key step in a workup for DVT.
  
• A careful history and physical exam, interpreted in the context of the risk-factor profile, is the most important driver of subsequent diagnostic evaluation as individual clinical findings are poorly predictive in isolation.
  
• Consider further evaluation for underlying malignancy when appropriate as VTE may be initial manifestation.
  

D
-dimer testing:

• D
  -dimer, a byproduct of endogenous clot formation, is becoming increasingly used in evaluation of patients for DVT and PE.
  
• Only useful when the result is negative
  (to exclude DVT). Positive
  D
  -dimer does not make the diagnosis; it only mandates further testing.
  
• Methods of measuring
  D
  -dimer levels:
  
  • Latex agglutination (1st-generation tests) and microlatex agglutination (2nd-generation) are generally insufficient.
    
  • Whole-blood latex agglutination (SimpliRED) is valuable if negative in low probability patients (using Wells criteria).
    
  • Enzyme-linked immunosorbent assay (ELISA) testing gives a quantitative result and has been validated in large clinical studies in ED patients; particularly when combined with assessment of pretest probability
    

• Contrast venography:
  
  • Once the imaging test of choice; now rarely performed because it is invasive, expensive, and has complications.
    
  • Involves injection of contrast medium into a leg vein, which can cause thrombophlebitis in patients undergoing the procedure; as well as contrast dye reactions and possible renal damage
    
• Compression US:
  
  • Standard 1st-line diagnostic test
    
  • Venous study. Normal veins compress; those with clots do not.
    
  • Color Doppler can be useful for identifying the vein but does not add substantially to accuracy. Duplex scanning refers to the combination of compression B-mode US and color Doppler.
    
  • Has a sensitivity in the high 90% range
    
  • Should be repeated (or followed up with contrast venography) in high-risk patients with negative US.
    
• Other tests include radionuclide venography and impedance plethysmography; however, these are not commonly used in clinical practice
  

• Superficial thrombophlebitis
  
• Cellulitis
  
• Torn muscle and/or ligaments (including plantaris and gastrocnemius tears)
  
• Ruptured Baker cyst
  
• (Bilateral) edema secondary to heart, liver, or kidney disease
  
• Venous valvular insufficiency
  
• Drug-induced edema (calcium channel blockers)
  
• (Unilateral) edema from abdominal mass (gravid uterus or tumor) or lymphedema
  
• Postphlebitic syndrome (from prior thrombophlebitis)
  

TREATMENT