Lab Values

Lab Values

  1. Why Learn Lab Values?
    1. Reasons Against:
      1. We don’t draw labs
      2. It won’t change our treatment
      3. We treat signs and symptoms, not numbers
      4. How often have you walked into a facility for an IFT and they spew off labs which mean nothing to you, knowing you won’t use them for your 10 minute transport. I used to get this, nod and smile, then take the Pt. Most of the time they were stable and I could treat any symptom they had.
    2. Reasons For:
      1. EMS seems to be changing towards doing labs
        1. Already performing blood glucose
      2. Prehospital lab draws for trauma, stroke, CVA Pts
      3. With Medicare/Medicaid holding back reimbursements for unwarranted transports and ER visits, we’re seeing a growth in community health paramedicine
      4. Highly important for interfacility transports, especially long ones.
      5. Better integration and collaboration of EMS with hospitals/clinics
      6. Boosts image of EMS as a sector of medicine
      7. Possibly the most important reason: It will make you a better provider. As medics, we are detectives, looking for clues as to what is going on and how we can improve a Pt’s condition based off what we know. Understanding what is going on with your Pt, whether you use the info to guide your treatments will always make you better.
    3. What We’ll cover:
      1. Basic lab values
        1. Their significance
        2. Key tips to improve and guide your care
    4. What we won’t cover:
      1. Every lab and application
      2. This is a basic overview of labs, hopefully to pique your interest for further research
      3. One thing I encourage you to do is the next time you come across a lab value for a Pt, whether being sent with you on an IFT, or maybe after follow up with a Pt, is to look it up, it’s significance, how it pertains to your Pt. Don’t try and learn everything at once, but engrain what you come across in your time in the field.
  2. Blood:
    1. Consists of plasma (55%) and blood cells (45%)
    2. Plasma:
      1. 7% Protein, 91% Water, 2% Other solutes
        1. Protein:
          1. Albumin 58% - “maintains oncotic pressure in the blood” (Fundamentals of Nursing pg. 588). Main component responsible for keeping fluids from leaking out of circulatory system.
          2. Globulin 38% - assist in transporting various substances through the blood and play a role in the immune system
          3. Fibrinogen 4% - maintains a crucial role in clot formation as it is converted into insoluble fibrin
        2. Other solutes:
          1. Ions, Nutrients, Waste Products, Gases, Regulatory Substances
      2. Serum is plasma w/o its clotting factors
    3. Blood cells:
      1. RBC: O2 & CO2 transport
        1. RBC is mostly made up of hemoglobin to which O2 and CO2 bind (respectively, to iron and globin, the simple protein part)
      2. WBC: Infection
        1. Neutrophils (50-70%)
          1. Primary phagocytic cell in the inflammatory process
          2. Mature is called “segmented neutrophil”
          3. Immature is called a “band” (appearance of the nucleus) or stab
          4. Increased bands (>10%) is a sign of infection and a diagnostic criteria for sepsis (body so overwhelmed it’s “sending the kids to war”) – SIRS criteria
        2. Lymphocytes (20-40%)
          1. High: Usu. Viral infection
          2. Low: Assoc. with infection
        3. Monocytes (4-8%)
        4. Eosinophils (0-4%)
        5. Basophils (0-2%)
      3. Platelets: Coagulation
        1. Usually an issue of too many, too few, or altered function
  3. CBC (Values taken from Mayo Clinic: http://www.mayoclinic.org/tests-procedures/complete-blood-count/details/results/rsc-20257186)
    1. RBC
      1. Male: 4.3 – 5.7 trillion cells/L
      2. Female: 3.9 – 5.0 trillion cells/L
    2. WBC
      1. 3.5 – 10.5 billion cells/L
        1. SIRS Criteria: WBC </= 4 or >/= 14
          1. High or low, consider infection (“either trying to fight or giving up”)
        2. Some types of leukemia produce very high WBC counts, may point to the etiology depending on how high
        3. If <4.0 may be: Bone marrow depression, chronic illness, some types of leukemia
      2. WBC differential (http://emedicine.medscape.com/article/2085133-overview)
        1. Neutrophils - 2.0–7.0×10 9/l (40–80%)
        2. Lymphocytes - 1.0–3.0×10 9/l (20–40%)
        3. Monocytes - 0.2–1.0×10 9/l (2–10%)
        4. Eosinophils - 0.02–0.5×10 9/l (1–6%)
        5. Basophils - 0.02–0.1×10 9/l (< 1–2%)
          1. May be given as a percentage or an absolute. The absolute is usually more pertinent than the percentage b/c percentage can be relative to the other values.
    3. HGB
      1. Male: 13.5 – 17.5 gm/dL
      2. Female: 12.0 – 15.5 gm/dL
    4. HCT: portion of blood that is not plasma (a measure of the amount of RBCs in the blood), 40% HCT = 40ml RBC in 100ml blood
      1. Male: 39 – 50%
      2. Female: 35 – 45%
    5. PLT:
      1. 150 – 450 billion/L
    6. MCV (avg. RBC size)
  4. CBC Application
    1. Decreased RBC
      1. Consider anemia, source of hypoxia, ask, “Why is it low?”
    2. WBC:
      1. Consider infection. Look for source then follow local sepsis treatment protocols.
    3. HGB
      1. If low consider anemia
      2. If elevated consider dehydration
    4. HCT:
      1. Consider dehydration as a cause to why this is high. Since it is a calculated ratio of RBCs in total volume, as volume drops, RBC ratio is higher.
    5. PLT:
      1. Will they be clotting okay?
  5. PT, PTT, aPTT, INR, Fibrinogen
  6. Cardiac Enzymes
    1. Troponin: what you will hear most
      1. >0.04 has potential for concern
  7. Detected within 4-6 hrs of MI or injury (pg 670 Med-Surg Nursing)
  8. Peak at 10-24 hrs
  9. May be present for 10-14 days
  10. Elevated troponin does not always mean heart attack.
    1. May also be elevated if body is being overly exerted (http://www.onlinejacc.org/content/56/3/169)
  11. BNP
    1. Brain Natriuretic Peptide b/c first discovered in brain. Now often called B-Type Natriuretic Peptide, released in the ventricles due to myocardial stretching.
    2. What happens is: The Renin-Angiotensin-Aldosterone system operates to regulate sodium concentration and BP. Those in CHF have fluid buildup which the L ventricle can’t handle will. The body releases BNP, interfering with aldosterone and renin release from the kidneys, which interferes with the body trying to hold onto salt (and water), this keeps the heart from being overstretched by a reduction in retained water. Increased BNP = Decreased overstretching of the heart (to some extent)
    3. >100 pg/ml à diagnostic for heart failure (Med-Surg Nursing pg 673)
    4. Often seen much higher (hundreds) in congestive heart failure Pts)
  12. Blood gas analysis
    1. Acid/Base Balance, Oxygenation, Shock
      1. Basics of oxygen transport/perfusion
        1. ATP
          1. 38 ATP total w/ normal aerobic metabolism. CO2 and H2O primary byproducts
          2. 2-4 ATP in anaerobic metabolism. Lactic acid primary byproduct.
          3. Lactate is gold standard test for shock. (>2.0 mmol/L)
        2. CO2: Byproduct of respiration
        3. O2
        4. Anion Gap:
          1. Acidosis causes an increase in H+ ions (cation, b/c it lost an electron). The additional cations bind to existing anions (Cl- and HCO3-) making them unmeasurable and effectively dropping the CL- and CO2 levels. This causes an increase in AG.
          2. Acidosis w/o ABGs or a Lactate?
          3. *Anion gap (cations - anions):
          4. (Na+ + K+) − (Cl- + HCO3−) = 16 mEq/L
          5. 8 - 16 normal (K+ not factored)
          6. 10 - 20 w/ K+ factored
          7. *AG > 20 = metabolic acidosis
          8. *The higher the AG the worse the acidosis
        5. Measuring CO2 in the prehospital environment:
          1. Capnoline and EtCO2:
            1. Approx. 3-5 mmHg less then PaCO2
              1. For offgassing of CO2 a negative pressure gradient between the lungs and venules is required
            2. Knowing the exact PaCO2 isn’t necessary, trending is what we should follow
      2. Buffer systems
        1. Bicarbonate buffer system
        2. Respiratory
        3. Renal
      3. Normal ABG Parameters
        1. pH
        2. PaCO2
        3. HCO3
        4. PaO2
        5. SaO2
        6. BE
      4. PaO2 should be approx. FiO2 x 5
        1. 0.21 x 5 = 100%
        2. Use for trending:
          1. Pt on 40% FiO2 and P02 of 160. Now on 70% FiO2 and PO2 of 200.
            1. Pt’s condition is deteriorating quicker than treatments are taking effect.
        3. PaO2/FiO2 Ratio (normal 500, ALI 300, ARDS 200)
      5. Tips for using trending ABGs
        1. ↑ CO2 10 mmHg = ↓ pH 0.08
        2. ↑ HCO3 10 mEq = ↑ pH 0.15
        3. Change in PaCO2 of 10 mmHg = change in K+ of 0.5 mEq/L
        4. Change in pH of 0.1 = change in K+ of 0.6 mEq/L
        5. ↑ pH = ↓ CO2 = ↓ K+
        6. Bicarb. replacement formula:
          1. Kg / 4 x Base Deficit = mEq bicarb. Needed
      6. Oxyhemoglobin Dissociation Curve
        1. L shift = alkalosis (increase SaO2)
        2. R shift = acidosis (decrease SaO2)
        3. Describe 2-3 DPG
      7. Note on ventilation and oxygenation
        1. Start ventilation volumes at 6 cc/kg IBW
        2. IBW:
          1. Males: 52 kg + 1.9 kg for every inch over 5 ft
          2. Females: 49 kg + 1.7 kg for every inch over 5 ft
  13. Basic Metabolic Panel
    1. Na+ (136 - 144 mEq/L)
    2. Cl- (95 - 105 mEq/L)
    3. BUN (7 – 20 mg/dL)
    4. K+ (3.5 – 5.0 mEq/L)
    5. CO2 (23 - 29 mEq/L)
    6. Creatinine (0.8 – 1.2) mg/dL
    7. Glucose (70 – 110 mg/dL)
  14. Comprehensive Metabolic Panel (CMP)
    1. Liver Panel: (http://www.webmd.com/digestive-disorders/tc/liver-function-panel-topic-overview)
      1. Albumin: 3.5 – 5.0 g/dL
        1. Higher: Dehydration
        2. Lower: Chronic liver disease, malabsorption, malnutrition, nephrotic syndrome (Fundamentals pg 1655)
      2. Alkaline phosphatase: 44 to 147 IU/L (0.73 to 2.45 µkat/L)
      3. ALT (alanine aminotransferase): 7 to 40 IU/L (0.12 to 0.67 µkat/L)
      4. AST (aspartate aminotransferase): 10 to 34 IU/L (0.17 to 0.57 µkat/L)
      5. Total bilirubin: 0.3 to 1.9 mg/dL (5.0 to 32.5 µmol/L)
      6. Total protein: 6.0 to 8.3 g/dL (60 to 83 g/L)
    2. Calcium: 8.5 to 10.2 mg/dL (2.13 to 2.55 mmol/L)
  15. Urinalysis (http://emedicine.medscape.com/article/2074001-overview)
    1. Normal values are as follows:
    2. Color – Yellow (light/pale to dark/deep amber)
    3. Clarity/turbidity – Clear or cloudy
    4. pH – 4.5-8
    5. Specific gravity – 1.005-1.025
    6. Glucose - ≤130 mg/d
    7. Ketones – None
    8. Nitrites – Negative
    9. Leukocyte esterase – Negative
    10. Bilirubin – Negative
    11. Urobilirubin – Small amount (0.5-1 mg/dL)
    12. Blood - ≤3 RBCs
    13. Protein - ≤150 mg/d
    14. RBCs - ≤2 RBCs/hpf
    15. WBCs - ≤2-5 WBCs/hpf
    16. Squamous epithelial cells - ≤15-20 squamous epithelial cells/hpf
    17. Casts – 0-5 hyaline casts/lpf
    18. Crystals – Occasionally
    19. Bacteria – None
    20. Yeast - None

Content Creator: Ariel Wei

CAPCE Course Number: 17-EMTP-F3-1201

Total CE Hours: 1

Level: Advanced

EMT-CE uses the NEMSES guidelines as the foundation for every course outline.