Anesthesia Laboratory Medicine

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Anesthesia Laboratory Medicine
2015-09-01 02:03:20
Labs Values

Arterial Blood Gas Values
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  1. Blood Urea Nitrogen (BUN)
    • Normal: 8-20mg/dL
    • Waste product from protein metabolism
    • Increased: Impaired Renal Function, Dehydration, CHF, AMI, high protein intake, GI blood
    • Decreased: Liver failure, malnutrition, over hydration, SIADH
  2. Serum Creatinine
    • Normal: 0.6-1.5mg/dL
    • Waste product of creatine phosphate in skeletal muscle
    • >2.0 = 50% nephron loss
    • >4.8 = 75% nephron loss
    • >10 = 90% nephron loss (ESRD)
    • Increased: Impaired renal function, chronic nephritis, muscle disease, CNF, shock
    • Decrease: Decreased muscle mass/ atrophy, inadequate dietary protein
  3. BUN/Creatinine Ratio
    Normal: 10-20:1Elevated: Resorption of Hematoma (increased protein), GI Bleed, obstructive uropathies, decreased tubular flow (CHF, cirrhosis, nephrotic syndrome)Normal: Dehydration (high values of both)
  4. Creatinine Clearance
    M: 95-135ml/minF: 85-125ml/minRate of creatinine clearance from kidneysMeasure of GFRDecreases 10% per decade after 50yo<10ml/min = dialysis
  5. Serum Osmolality
    Normal: 282-295mOsm/kgOsmotic concentration of fluid: dependent on active ions and moleculesIncreased: Renal disease, CHF, dehydration, diabetes insipidus, DM/hyperglycemiaDecreased: Sodium loss, SIADH, overhydration
  6. COX-1 Protective Effects
    Promotes gastric protection: + Gastric protection and - Gastric AcidPromotes platelet aggregation: + thromboxane formationPromote renal vasodilation: + renal prostaglandin formation
  7. COX-2 Protective Effects
    Promotes Renal Vasodilation: + Renal prostaglandin formationAdverse: Inflammatory, pain, and fever
  8. NSAID Drug Interactions
    • Decreased Effect of Anti-HTN and Diuretics: -GFR and + Renin Release
    • Acute Renal Failure: ACEIs, ARBs, B-Blockers
  9. Renal Blood Flow Regulation
    • Prostaglandins: Vasodilation of Afferent Arteriole (+GFR)- Blocked by NSAIDs
    • Angiotensin II: Vasoconstriction of Efferent Arteriole (+GFP)- Blocked by ACEIs, ARBs, and B-Blockers
  10. NMB & Reversal Agents
    • Cisatracurium: Hoffman Elimination
    • Rocuronium: Hepatic Metabolism
    • Vecuronium: 30% renal excretion
    • Neostigmine: 50% renal excretion
    • Edrophonium: 75% renal excretion
  11. Transaminases (ALT & AST)
    • ALT: 10-32 U/L
    • AST: 12-31 U/L
    • Over 100 U/L is significant
    • Released in response to injury
    • Does not predict severity of Liver disease
    • AST increased in skeletal/cardiac muscle injury
    • ALT is more specific for liver
  12. Albumin
    • Normal: 3.5-5.0 g/dL 
    • Half-life: 14-21 days
    • Indirect measure of  synthetic capacity
    • <2.5 d/dL may indicate severe disease
    • Low Albumin = more free drug
    • Low albumin: malnutrition, ascites, nephrotic syndrome
  13. Prothrombin Time
    • Normal: 10-12 sec
    • Half-Life: 6 hours
    • Good qualitative indicator of liver function
  14. Gamma-Glutamyl Transpeptidase (GGT)
    • Normal: 0-51 IU/L
    • Used for synthesis of Glutathione
    • Increased in alcoholism, phenytoin, and oral contraceptives
    • Sentitive to hepatocyte damage
    • Distinguish liver from bone disease when alkaline phosphatase is elevated
  15. Alkaline Phosphatase
    • Normal: 90-240 U/dL
    • Elevated: Obstructive liver/biliary disease, disease of rapidly growing bone, pregnancy,
  16. Hemolysis/Gilberts
    • B: Elevated unconjugated
    • AST/ALT: N
    • Alk Phos: N
    • Albumin: N
    • PT: N
  17. Acetaminophen Induced Hepatitis
    • N-acteyl-p-aminophenol
    • Analgesic and antipyretic
    • Poor anti-inflammatory
    • 5-10% converted to NAPQI (detoxified by glutathione)
    • NAPQI causes hepatic damage
    • CYP 2E1 & CYP 3A4 Dependent
  18. Infiltrative Disease
    • B: Normal
    • AST/ALT: Normal or slightly elevated
    • ALP: Elevated over 4x (GGT, 5'N)
    • A: Normal
    • PT: normal
  19. Obstructive Jaundice
    • B: Both elevated
    • AST/ALT: moderate elevation
    • ALP: Elevated over 4x
    • A: Normal (unless chronic)
    • PT: Normal/ prolonged
  20. Alcoholic Hepatitis/Cirrhosis
    • B: Both elevated
    • AST/ALT: Over 2x (suggestive), Over 3x (diagnostic)
    • Alk Phos: Under 3x normal
    • Albumin: Decreased 
    • PT: Prolonged
  21. Chronic Hepatocellular Disease
    • B: both elevated
    • AST/ALT: Elevated <330 U/L
    • Alk Phos:Elevated less than 3x normal
    • Albumin: Decreased
    • PT: Prolonged
  22. Acute Hepatocellular Disease
    • B: Both elevated
    • AST/ALT: Elevated (ALT > AST)
    • Alk Phos: Elevated less than 3x normal
    • Albumin: N
    • PT: Usually N
  23. Bilirubin
    • Normal: Total < 1.1 mg/dL
    • Jaundice: > 2 mg/dL
    • Breakdown product of heme, myoglobin, cytochrome enzymes
    • Unconjugated (Indirect) bilirubin to conjugated (Direct) bilirubin for urinary excretion
    • Unconjugated bilirubin can lea to encephalopathy.
  24. Sodium
    Normal: 136-145mmol/L
  25. Hyponatremia
    • Due to water retention or water intake exceeds kidney excretion
    • Extracelluler hypotonicity causes cerebral edema, +ICP, 
    • Usually seen with hypo-osmolality
    • Exceptions: Addition of osmotically active solute (mannitol, glucose, glycine) and pseudohyponatremia (solid phase of plasma is increased from hyperlipidemia or paraproteinemic disorder)
    • Tx: Loop diuretic, withhold water, hypertonic saline (3% NaCl) only if significant symptoms, slowly treat chronic hyponatremia to avoid side affects (demyelination, quadriplegia, seizures, coma, death), ACEi for patients with hypervolemia due to CHF
  26. Hypernatremia
    • Seen with hyerosmolality and causes cellular dehydration/shrinkage
    • S&S: restlessness, muscular twitching, hyperreflexia, tremors
    • Dehydration of brain cells (hemorrhage), capillary and venous congestion, and venous sinus thrombosis
    • Tx: Hypovolemic (water replacement), hypervolemia (loop diuretic or possibly hemodialysis), euvolemia (water replacement)
  27. Potassium
    • Normal: 3.5-5 mmol/L
    • Major Intracellular Cation
  28. Hypokalemia
    • Signs: Cardiac (dysrhythmias) and neuromuscular (muscle weakness, cramps, paralysis, and ileus)
    • Tx: serious signs require IV K, correct prior to surgery (especially with other risk factors for dysrhythmias such as CHF or digoxin)
    • Anesthesia: avoid further decreases in K which may be caused by Beta agonists, insulin, glucose, bicarbonate, and diuretics, or by hyperventilation and respiratory alkalosis; it may cause prolonged action of muscle relaxants
  29. Hyperkalemia
    • S/S: chronic hyperkalemia may cause general malaise and mild GI disturbances. Acute/significant increases manifest as cardiac and neuromuscular changes (weakness, paralysis, nausea, vomiting, and bradycardia/asystole). 
    • Tx: Immediately required if life-threatening dysrhythmias are present, CaCl2 or Ca-gluconate IV, K can be driven intracellularly by insulin, NaHCO3 and hyperventilation are adjuvant therapies, elimination of K by loop diuretic, saline infusion, or an ion exchange resin, dialysis if poor renal function
    • Anesthesia: Lower K immediately if surgery cannot be postponed, avoid succinylcholine, induction and maintenance drugs are okay, avoid respiratory or metabolic acidosis, IV fluids should be K-free (avoid lactated Ringer's and Normosol)
  30. Calcium
    • Normal: 9-11mmol/L
    • Regulated by PTH (increase bone resorption and renal tubular reabsorption), calcitonin (inhibits bone resorption), and vitamin D (augments intestinal absorption of Ca)
    • 1% of total body calcium is in the ECF (99% in bone)
  31. Hypocalcemia
    • Alkalosis reduces ionized Ca concentration 
    • S/S: CV and neuromuscular (paresthesia, irritability, seizures, hypotension, and myocardial depression)
    • Cause: PTH or Vitamin D disorders
    • Tx: IV Ca, may also have to replenish Mg, correct alkalosis, correct Ca before acidosis
    • Anesthesia: Minimize further Ca decrease (hyperventilation or bicarbonate may cause this), decrease in Ca due to massive transfusion of citrate containing blood)
  32. Hypercalcemia
    • Causes: Increased Ca absorption from GI, decreased renal excretion, and increased bone resorption
    • S/S: neurologic and GI (confusion, hypotonia, depressed deep tendon reflex, lethargy, abdominal pain, and nausea/vomiting)
    • Dx: hyperparathyroidism or cancer are common
    • Tx: Increase urinary Ca excretion and inhibit bone resorption/further GI absorption, 
    • Anesthesia: Restore Ca w/ IV volume and increase urinary excretion of Ca w/ loop diuretics (avoid thiazides), caution with NMBs
  33. Hematology Basics
    • Blood: 5L
    • Plasma: 3L
    • Cells: 2L
    • Cellular component: RBCs, WBCs, platelets
    • Bone Marrow: cell production
  34. RBC Count
    • Normal (M): 4.6-5.9x10^6/mm3
    • Normal (F): 4.2-5.4x10^6/mm3
    • Required for O2 and CO2 transport
    • Polycythemia: high altitude, athletes, COPD, cyanotic heart defect, polycythemia vera (PV)
    • Anemia: Secondary to decrease in number or Hb
    • Life Span: 4 months
    • Reticulocytes (immature): 0.5-1.5%(M); 0.5-2.5%(F)
  35. Hemoglobin (Hb)
    • Normal(M): 13-18g/dl
    • Normal(F): 12-16g/dl
    • Iron containing pigment (heme) bound to protein (global)
    • O2 carrying capacity proportional to Hb
    • Decreased Hb: RBC loss (blood loss, marrow suppression), Iron deficiency (hypo chromic)
  36. Hematocrit (Hct)
    • Normal(M): 45-52%
    • Normal(F): 37-48%
    • Percentage of RBC in plasma
    • About 3x Hb
  37. Mean Corpuscular Volume (MCV)
    • Normal(M): 80-90
    • Normal(F): 82-98
    • Size of RBCs
    • Normocytic: Acute Hemorrhage
    • Macrocytic: B12 and Folic Acid Deficiencies
    • Microcytic: Fe Deficiency, thalessemia
  38. Mean corpuscular hemoglobin (MCH)
    Normal: 27-31 picograms
  39. Mean corpuscular [Hemoglobin] (MCHC)
    Normal: 32-36%
  40. White Blood Cells (WBCs)
    • Total WBCs: 4000-10,000
    • Life Span: 13-20 days
    • WBCs fight infection: phagocytosis and antibodies (production, transport, and distribute)
    • Also called leukocytes
    • Destroyed in Lymphatic System
    • Immature cells called "bands" (3-5%)
  41. Leukocytosis
    • Increase in WBCs: Over 10,000
    • Neutrophilia, Basophilia, Eosinophilia
    • Lymphocytosis, monocytosis
    • Process: 1. Acute infection/trauma/inflammation, 2.Colony Stimulating Factor (CSF), 3. Bone Marrow stimulation
    • WBC> 30,000: Massive infection or leukemia
  42. Leukopenia
    • WBCs: < 4,000
    • Secondary to viral infections, bacterial infections, bone marrow disorders, drugs
    • WBCs < 500: risk of fatal infection
  43. Neutrophils
    • Normal: 50-70% WBCs
    • aka Polymorphonucleocytes (PMNs)
    • Granulocytes
    • Primary defense: infection/stress
    • Left shift: Acute bacterial infection an increased neutrophils
    • Neutropenia: Typhoid, TB, viral infection, drugs (TCAs)
  44. Eosinophils
    • Normal: 1-4% of WBCs
    • Associated w/ Antigen-antibody rxns
    • Granulocytes
    • Increased: Allergic rhinitis, asthma, drug hypersensitivity
    • Decreased: corticosteroid use
  45. Basophils
    • Normal: 0.5-1.0% of WBCs
    • aka Mast Cells (granulocytes)
    • Contain heparin, histamine, and 5-HT
    • Increased: Leukemia, Hodgkin's
    • Decreased: corticosteroid, allergic reactions, infection
  46. Lymphocytes
    • Normal: 25-40% WBCs
    • B-Lymphocytes: Antibodies (produced and mature in BM)
    • T-lymphocytes: T4 Helper, Killer, Cytotoxic, T8 suppressor (produce in BM & mature in thymus)
    • Increase: Virus, TB, Lymphocytic Leukemia
    • Decrease: AIDS, Corticosteroids, Drugs
  47. Monocytes/Macrophages
    • Normal: 2-8%
    • Largest cells in blood
    • Phagocytosis
    • Produce: Interferon, IL-1, TNF, Growth factors, 
    • Increased: TB, malaria, monocytic leukemia, ulcerative colitis, regional enteritis
  48. Chloride
    Normal: 98-106 mmol/L
  49. Bicarbonate
    Normal: 20-29mmol/L
  50. Partial Thromboplastin Time (PTT)
    • Normal: 25-35 sec
    • Intrinsic
    • Factors I,II,V,VIII,IX,X,XI,XII
    • heparin Increases
  51. Prothrombin Time (PT)
    • Normal: 12-14 sec
    • Extrinsic 
    • Factors: I, II, V, VII, X (Vitamin K)
    • Coumadin/Warfarin increases
  52. International Normalized Ratio (INR)
    • Normal: 0.8-1.2
    • Warfarin Therapy Target: 2-3
    • Compares PT from one lab to another
  53. Platelets
    • Normal: 150,000-300,000 cells/uL
    • Thrombocytopenia: <100,000 cells/uL
    • Surgical Hemostasis: >50,000 needed
    • Spontaneous bleeding: <20,000 cells/uL
    • Life span: 9-11 days
  54. pH
    • Normal: 7.35-7.45
    • Intracellular: 7.0-7.3
  55. Arterial Carbon Dioxide Tension (PaCO2)
    Normal: 35-45mm Hg
  56. Arterial Oxygen Tension (PaO2)
    Normal: 80-100mm Hg
  57. Glucose
    • Normal (resting): 70-110mg/dL
    • HbA1c: <5.6%
    • Pre-Diabetic: 5.7-6.4%
    • Diabetic: >6.4%
    • Estimates: 5%=100,6%=125,7%=150, 1%=25mg/dL
  58. Magnesium
    • Normal: 1.5-2.5mEq/L
    • Hypomagnesemia: Anticipated dysrhythmias, similar symptoms to hypocalcemia, avoid diuretics (Mg follows Na excretion)
    • Hypermagnesemia: S/S @4-5mEq/L, exacerbated by acidosis,
  59. Acidosis
    Major adverse effects at a pH < 7.2 include decreased inotropy which may be increased in patients with LV dysfunction or myocardial ischemia or with sympathetic impairment (B-blockers or GA)
  60. Alkalosis
    Major adverse effects at pH > 7.6. Reflect impairment of cerebral and coronary blood flow due to arteriolar vasoconstriction. Associated decreases in Ca contribute to neurologic abnormalities. Increase in ventricular dysrhythmias and depresses ventilation.