Labs

  • Arterial Blood Gas (ABG)
  • Basic Metabolic Panel (BMP)
  • Coagulation Panel
  • Complete Blood Count (CBC)
  • Lactate

Arterial Blood Gas (ABG)

  • Background
    • An arterial blood gas (ABG) measures the acidity of the blood as well as the presence of oxygen and carbon dioxide. It can be used to evaluate the acid-base status of the body, check for hypercapnia (high CO2), and evaluate for hypoxia (low oxygen levels).
  • Findings/Interpretation
    • Respiratory Acidosis
      • pH ↓  CO2 ↑  Bicarb (normal)
      • Causes include hypoventilation, COPD, asthma
    • Respiratory Alkalosis
      • pH ↑ CO2 ↓  Bicarb (normal)
      • Causes include hyperventilation, altitude sickness, hepatic failure, anxiety
    • Metabolic Acidosis
      • pH ↓  CO2 (normal)  Bicarb ↓
      • Causes include DKA, sepsis, severe diarrhea
    • Metabolic Alkalosis
      • pH ↑ CO2 (normal)  Bicarb ↑
      • Causes include severe vomiting, Cushing’s disease, nasogastric tube suction, diuretics
Video Credit: Zero To Finals

*Deep Dive: VBG vs ABG in the ED (NUEM)



Basic Metabolic Panel (BMP)

  • Background
    • The basic chemistry panel – also called BMP or Chem 7 – evaluates several key electrolytes in the blood as well as marker of renal function. This includes sodium (Na), potassium (K), chloride (Cl), carbon dioxide (CO2), blood urea nitrogen (BUN), creatinine and glucose
  • Findings/Interpretation
    • Hypernatremia
      • Dehydration,diabetes insipidus, Cushing’s disease
    • Hyponatremia
      • Excess body water (CHF, renal failure, etc.), hypothyroidism, vomiting, diarrhea, pancreatitis
    • Hyperkalemia
      • Renal failure, Addison’s disease, dehydration, ACE inhibitors, spironolactone
    • Hypokalemia
      • Diuretics, NG suctioning, vomiting, diarrhea, metabolic alkalosis
    • Hypercalcemia
      • Hyperparathyroidism, malignancy, renal failure, thiazides, Addison’s disease, vitamin D intoxication
    • Hypocalcemia
      • Hypoparathyroidism, vitamin D deficiency, alcoholism, sepsis, pancreatitis, hypomagnesemia
    • Hyperchloremia
      • Diarrhea, hyperalimentation
    • Hypochloremia
      • Vomiting, renal disease, diabetic ketoacidosis
    • Hyperglycemia
      • Diabetes, Cushing’s syndrome, pancreatitis, thiazide diuretics
    • Hypoglycemia
      • Liver disease, malnutrition, sepsis, endocrine tumors
    • Azotemia
      • Renal injury/failure, CHF, aminoglycosides
Video Credit: ICU Advantage

*Deep Dive: Use of a Comprehensive Metabolic Panel Point-of-Care Test to Reduce Length of Stay in the Emergency Department: A Randomized Controlled Trial (Annals of Emergency Medicine)



Coagulation Panel

  • Background
    • The coagulation panel consists of two different measures of blood clotting. Prothrombin time (PT) and partial thromboplastin time (PTT) can be increased due to underlying conditions or blood thinning medications
  • Findings/Interpretation
    • Prolonged PT (INR)
      • Warfarin (low dose)
      • Mild vitamin K deficiency
      • Factor VII deficiency
    • Prolonged APTT
      • Von Willebrand disease
      • Unfractionated heparin
      • Overcoagulation w/ low molecular weight heparin
      • Factor inhibitors
      • Factor VIII, IX, VI, or XII deficiency
      • Antiphosopholipid antibody
    • Prolonged PT(INR) and APTT
      • Liver disease
      • DIC
      • High hematocrit
      • Common pathway deficiency (X, V, II, fibrinogen)
      • Excess heparin
      • Severe vitamin K deficiency
      • Factor IIa inhibitors (dabigatran
      • Factor Xa inhibitors (rivaroxaban, apixaban)
Video Credit: ICU Advantage

*Deep Dive: When should you obtain coagulation tests in the emergency department? (emDocs)



Complete Blood Count (CBC)

  • Background
    • The complete blood count (CBC) measures multiple types of blood cells. This includes the number of white blood cells, considered a marker of infection or inflammation; amount and percentage of red blood cells, the oxygen carrying cells; and platelets which are a key component of blood clotting
  • Findings/Interpretation
    • WBC
      • Leukocytosis
        • Infection, pain, surgery, hypoxia, trauma, burns, infarctions, uremia, DKA, drugs (epinephrine, corticosteroids, lithium, cocaine)
      • Leukopenia
        • Malignancy, B12 or folate deficiency, aplastic anemia, sepsis, autoimmune disorders, splenic sequestration, radiation exposure
    • Hemoglobin
      • Anemia
        • Hemorrhage, iron deficiency, chronic disease, cancer, HIV, nutritional deficiencies (iron, B12, folate, malnutrition), hemolytic disease, pregnancy.
      • Polycythemia
        • Dehydration, tobacco use, renal cell carcinoma, chronic heart/lung disease, living at high altitude, hydronephrosis, EPO-secreting tumor, myeloproliferative disease
    • MCV
      • Microcytosis
        • “TICS” (Thalassemia, iron-deficiency, chronic disease, sideroblastic anemia)
      • Macrocytosis
        • B12 deficiency, folate deficiency, alcohol, liver disease, hypothyroidism
    • Platelets
      • Thrombocytopenia
        • Splenic sequestration, DIC, heparin-induced, nutritional deficiency (B12 or folate), liver disease, metastatic tumors, aplastic anemia, myelodysplasia
      • Thrombocytosis
        • Infection/sepsis, solid organ malignancies, post-splenectomy, anemia, chronic inflammatory disorders (TB, sarcoidosis, auto-immune), polycythemia vera, myelofibrosis, chronic myeloid leukemia
Video Credit: ICU Advantage

*Deep Dive: The CBC and the Man Behind the Curtain (Taming the SRU)



Lactate

  • Background
    • Lactate or lactic acid is used as a measure of tissue oxygenation and perfusion. Lactate is a normal product of cellular metabolism. Elevated lactate levels (type A) can be seen in conditions of hypoperfusion such as sepsis, hypovolemia, cardiac failure, seizure or cardiac arrest. Type B occurs without hypoperfusion and can be seen in diabetes, alcoholism and other conditions.
  • Findings/Interpretation
    • Lactic Acidosis
      • Type A (tissue hypoperfusion)
        • Hypovolemia
        • Sepsis
        • Cardiac failure
      • Type B (decreased utilization)
        • DKA
        • Metformin
        • Alcoholism
        • Liver disease
Video Credit: NURSINGcom

*Deep Dive: Utility of Obtaining a Lactate Measurement in the ED (emDocs)



Brandon Simpson, PA-C
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