Edema

Edema

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Edema, Fluid Overload, Generalized Edema

  • Definition
  1. Abnormal interstitial fluid accumulation in the intercellular space
  • Pathophysiology
  1. Mechanisms
    1. Loss of vascular integrity
      1. Changes in capillary hemodynamics
    2. Oncotic pressure gradient changes across the capillary membrane (between capillary and interstitial space)
      1. Increased tissue oncotic pressure (increased interstitial protein concentration) or
      2. Decreased plasma oncotic pressure (decreased Serum Albumin)
    3. Increase in capillary hydrostatic pressure
      1. Norepinephrine results in renal Vasoconstriction
      2. Renin results in Sodium absorption
      3. Aldosterone results in water retention
  2. Localized Edema
    1. See Localized Edema
  3. Generalized Edema
    1. See Generalized Edema Below the Diaphragm
    2. See Generalized Edema Above the Diaphragm
    3. Implies >3 Liters interstitial fluid accumulation
    4. Sodium and water retention mediated by renal Vasoconstriction and renin and aldosterone (as above)
      1. Kidney senses decreased perfusion
      2. Kidney senses decreased circulating volume
  • History
  1. Onset in last 72 hours?
    1. Exclude DVT, Cellulitis, Trauma
  2. Dependent Edema?
    1. Venous Insufficiency improves with limb elevation
    2. Will not improve with elevation in conditions with decreased plasma oncotic pressure (e.g. Cirrhosis, Nephrotic Syndrome, malabsorption)
  3. Unilateral or bilateral
    1. See Localized Edema Causes
    2. Generalized Edema Above the Diaphragm
    3. Generalized Edema Below the Diaphragm
    4. Medication Causes of Edema
  • Symptoms
  1. Unexplained weight gain
  2. Ring tightness
  3. Shoe tightness
  4. Facial swelling or puffiness
  5. Swollen arms or legs
  6. Abdominal Distention
  • Signs
  1. See Edema Exam
  2. Palpable swelling of skin or subcutaneous tissue
    1. Pitting Edema
    2. Non-Pitting Edema (Brawny Edema)
  • Diagnostics
  • Imaging
  1. Chest XRay Indications
    1. Dyspnea or
    2. BNP not available
  2. Echocardiogram Indications
    1. Suspected Pulmonary Hypertension (e.g. Obstructive Sleep Apnea)
    2. Suspected Congestive Heart Failure
      1. Increased BNP or
      2. Generalized Leg Edema in age over 45 years old (or other risks for Cardiomyopathy or CHF)
      3. Blankfield (1998) Am J Med 105:192-7 [PubMed]
  3. Extremity Doppler Ultrasound Indications
    1. Unilateral or asymmetric extremity edema
    2. Deep Vein Thrombosis suspected
    3. Confirm Venous Insufficiency
  4. Indirect radionuclide lymphoscintigraphy
    1. Confirmation of Lymphedema
  5. Magnetic Resonance Angiography with venography of lower extremity and Pelvis
    1. Pelvic or thigh Deep Vein Thrombosis suspected despite negative venous doppler Ultrasound
  • Labs
  • First-line
  1. B-Type Natriuretic Peptide
    1. CHF unlikely if BNP normal
      1. Test Sensitivity 90%: BNP <100 pg/ml
      2. Test Sensitivity 96%: BNP <50 pg/ml)
    2. Maisel (2001) N Engl J Med 347(3): 161-7 [PubMed]
  2. Urinalysis
    1. Evaluate for large Proteinuria (Nephrotic Syndrome)
  3. Comprehensive metabolic panel
    1. Renal Function test (Serum Creatinine, Blood Urea Nitrogen or BUN)
    2. Liver Function Test
      1. Optional if examiner can reliably exclude significant Ascites based on examination or Bedside Ultrasound
  • Labs
  • As indicated
  1. Serum Albumin
    1. Indicated for large Urine Protein positive suggestive of Nephrotic Syndrome
  2. Thyroid Stimulating Hormone (TSH)
  3. Urine test for Thiazides or Phenolphthalein
    1. Indicated in suspected Eating Disorder
    2. Confirms Diuretic abuse or Laxative abuse
  1. Most critical causes to exclude
    1. Congestive Heart Failure
    2. Nephrotic Syndrome
    3. Cirrhosis
  2. Diagnostics
    1. B-Type Natriuretic Peptide (BNP)
      1. Obtain Echocardiogram if BNP >100 pg/ml (especially if age >45)
    2. Basic metabolic panel
      1. Adding Liver Function Tests and Serum Albumin is optional (if Ascites excluded on exam or Bedside Ultrasound)
    3. Urinalysis
      1. Evaluate for large Proteinuria
    4. Bedside Abdominal Ultrasound
      1. Evaluate for Ascites (if body habitus or other confounding factors limit exam)
      2. Consider Inferior Vena Cava Ultrasound for Volume Status
  3. Consider important other diagnoses (if diagnostics and examination otherwise negative above)
    1. See Generalized Edema Below the Diaphragm
    2. See Generalized Edema Above the Diaphragm
    3. See Medication Causes of Edema
    4. Hypothyroidism
    5. Pelvic Mass
    6. Pregnancy Induced Hypertension (after 20 weeks gestation)
    7. Deep Vein Thrombosis evaluation indications
      1. Unilateral or asymmetric edema or
      2. Bilateral extremity edema and significant VTE Risk factors
        1. Cancer in last year
        2. Joint replacement
        3. Trauma
        4. Immobilization
        5. Hypercoagulability or prior Venous Thromboembolism
  4. Consider common alternative diagnoses (if diagnostics and examination otherwise negative above)
    1. Venous Insufficiency (most common)
    2. Lymphedema
      1. See Stemmer's Sign (pathognomonic)
    3. Cyclic edema
  • Management
  • General
  1. Treat specific underlying cause
  2. Diuretics if indicated (see below)
    1. Avoid in venous or lymphatic insufficiency
  3. Elevate legs
  4. Limit dietary Sodium to 1500-2000 mg/daily
  5. Compression Stockings (Venous Insufficiency)
    1. Contraindicated in Peripheral Arterial Disease (consider Ankle-Brachial Index before compression stocking use)
    2. Mild edema: 20-30 mmHg
    3. Severe edema: 30-40 mmHg
  1. Precautions
    1. Avoid Diuretics in conditions where they are unlikely to offer benefit
      1. Venous Insufficiency
      2. Lymphatic insufficiency (Lymphedema)
      3. Cyclic edema
    2. Close interval follow-up (within 7-10 days) to monitor progression
    3. Monitor Serum Potassium
    4. Monitor weight loss to keep above dry weight (base weight)
  2. Diuretic indications
    1. Pulmonary edema
    2. Congestive Heart Failure
    3. Nephrotic Syndrome
    4. Cirrhosis
  3. Diuretic dosing (initiation)
    1. Furosemide 10-20 mg orally twice daily
    2. Add Spironolactone in Cirrhotic Ascites
  • References
  1. Borhart et al in Majoewsky (2013) EM:Rap 13(7):5-6
  2. Traves (2013) Am Fam Physician 88(2): 102-110 [PubMed]