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abg presentation.ppt

  1. 1. Arterial Blood Gas Analysis Vanessa Klee MSIV
  2. 2. What is an ABG? <ul><li>The Components </li></ul><ul><ul><li>pH / PaCO 2 / PaO 2 / HCO 3 / O 2 sat / BE </li></ul></ul><ul><li>Desired Ranges </li></ul><ul><ul><li>pH - 7.35 - 7.45 </li></ul></ul><ul><ul><li>PaCO 2 - 35-45 mmHg </li></ul></ul><ul><ul><li>PaO 2 - 80-100 mmHg </li></ul></ul><ul><ul><li>HCO 3 - 21-27 </li></ul></ul><ul><ul><li>O 2 sat - 95-100% </li></ul></ul><ul><ul><li>Base Excess - +/-2 mEq/L </li></ul></ul>
  3. 3. Why Order an ABG? <ul><li>Aids in establishing a diagnosis </li></ul><ul><li>Helps guide treatment plan </li></ul><ul><li>Aids in ventilator management </li></ul><ul><li>Improvement in acid/base management allows for optimal function of medications </li></ul><ul><li>Acid/base status may alter electrolyte levels critical to patient status/care </li></ul>
  4. 4. Logistics <ul><li>When to order an arterial line -- </li></ul><ul><ul><li>Need for continuous BP monitoring </li></ul></ul><ul><ul><li>Need for multiple ABGs </li></ul></ul><ul><li>Where to place -- the options </li></ul><ul><ul><li>Radial </li></ul></ul><ul><ul><li>Femoral </li></ul></ul><ul><ul><li>Brachial </li></ul></ul><ul><ul><li>Dorsalis Pedis </li></ul></ul><ul><ul><li>Axillary </li></ul></ul>
  5. 5. Acid Base Balance <ul><li>The body produces acids daily </li></ul><ul><ul><li>15,000 mmol CO 2 </li></ul></ul><ul><ul><li>50-100 mEq Nonvolatile acids </li></ul></ul><ul><li>The lungs and kidneys attempt to maintain balance </li></ul>
  6. 6. Acid Base Balance <ul><li>Assessment of status via bicarbonate-carbon dioxide buffer system </li></ul><ul><ul><li>CO 2 + H 2 O <--> H 2 CO 3 <--> HCO 3 - + H + </li></ul></ul><ul><ul><li>ph = 6.10 + log ([HCO 3 ] / [0.03 x PCO 2 ]) </li></ul></ul>
  7. 7. The Terms <ul><li>ACIDS </li></ul><ul><ul><li>Acidemia </li></ul></ul><ul><ul><li>Acidosis </li></ul></ul><ul><ul><ul><li>Respiratory </li></ul></ul></ul><ul><ul><ul><li> CO 2 </li></ul></ul></ul><ul><ul><ul><li>Metabolic </li></ul></ul></ul><ul><ul><ul><li> HCO 3 </li></ul></ul></ul><ul><li>BASES </li></ul><ul><ul><li>Alkalemia </li></ul></ul><ul><ul><li>Alkalosis </li></ul></ul><ul><ul><ul><li>Respiratory </li></ul></ul></ul><ul><ul><ul><li> CO 2 </li></ul></ul></ul><ul><ul><ul><li>Metabolic </li></ul></ul></ul><ul><ul><ul><li> HCO 3 </li></ul></ul></ul>
  8. 8. Respiratory Acidosis <ul><li> ph,  CO 2,  Ventilation </li></ul><ul><li>Causes </li></ul><ul><ul><li>CNS depression </li></ul></ul><ul><ul><li>Pleural disease </li></ul></ul><ul><ul><li>COPD/ARDS </li></ul></ul><ul><ul><li>Musculoskeletal disorders </li></ul></ul><ul><ul><li>Compensation for metabolic alkalosis </li></ul></ul>
  9. 9. Respiratory Acidosis <ul><li>Acute vs Chronic </li></ul><ul><ul><li>Acute - little kidney involvement. Buffering via titration via Hb for example </li></ul></ul><ul><ul><ul><li>pH  by 0.08 for 10mmHg  in CO 2 </li></ul></ul></ul><ul><ul><li>Chronic - Renal compensation via synthesis and retention of HCO 3 (  Cl to balance charges  hypochloremia) </li></ul></ul><ul><ul><ul><li>pH  by 0.03 for 10mmHg  in CO 2 </li></ul></ul></ul>
  10. 10. Respiratory Alkalosis <ul><li> pH,  CO 2,  Ventilation </li></ul><ul><li> CO 2   HCO 3 (  Cl to balance charges  hyperchloremia) </li></ul><ul><li>Causes </li></ul><ul><ul><li>Intracerebral hemorrhage </li></ul></ul><ul><ul><li>Salicylate and Progesterone drug usage </li></ul></ul><ul><ul><li>Anxiety   lung compliance </li></ul></ul><ul><ul><li>Cirrhosis of the liver </li></ul></ul><ul><ul><li>Sepsis </li></ul></ul>
  11. 11. Respiratory Alkalosis <ul><li>Acute vs. Chronic </li></ul><ul><ul><li>Acute -  HCO 3 by 2 mEq/L for every 10mmHg  in PCO 2 </li></ul></ul><ul><ul><li>Chronic - Ratio increases to 4 mEq/L of HCO 3 for every 10mmHg  in PCO 2 </li></ul></ul><ul><ul><li>Decreased bicarb reabsorption and decreased ammonium excretion to normalize pH </li></ul></ul>
  12. 12. Metabolic Acidosis <ul><li> pH,  HCO 3 </li></ul><ul><li>12-24 hours for complete activation of respiratory compensation </li></ul><ul><li> PCO 2 by 1.2mmHg for every 1 mEq/L  HCO 3 </li></ul><ul><li>The degree of compensation is assessed via the Winter’s Formula </li></ul><ul><ul><ul><li> PCO 2 = 1.5(HCO 3 ) +8  2 </li></ul></ul></ul>
  13. 13. The Causes <ul><li>Metabolic Gap Acidosis </li></ul><ul><ul><li>M - Methanol </li></ul></ul><ul><ul><li>U - Uremia </li></ul></ul><ul><ul><li>D - DKA </li></ul></ul><ul><ul><li>P - Paraldehyde </li></ul></ul><ul><ul><li>I - INH </li></ul></ul><ul><ul><li>L - Lactic Acidosis </li></ul></ul><ul><ul><li>E - Ehylene Glycol </li></ul></ul><ul><ul><li>S - Salicylate </li></ul></ul><ul><li>Non Gap Metabolic Acidosis </li></ul><ul><ul><li>Hyperalimentation </li></ul></ul><ul><ul><li>Acetazolamide </li></ul></ul><ul><ul><li>RTA (Calculate urine anion gap) </li></ul></ul><ul><ul><li>Diarrhea </li></ul></ul><ul><ul><li>Pancreatic Fistula </li></ul></ul>
  14. 14. Metabolic Alkalosis <ul><li> pH,  HCO 3 </li></ul><ul><li> PCO 2 by 0.7 for every 1mEq/L  in HCO 3 </li></ul><ul><li>Causes </li></ul><ul><ul><li>Vomiting </li></ul></ul><ul><ul><li>Diuretics </li></ul></ul><ul><ul><li>Chronic diarrhea </li></ul></ul><ul><ul><li>Hypokalemia </li></ul></ul><ul><ul><li>Renal Failure </li></ul></ul>
  15. 15. Mixed Acid-Base Disorders <ul><li>Patients may have two or more acid-base disorders at one time </li></ul><ul><li>Delta Gap </li></ul><ul><ul><li>Delta HCO 3 = HCO 3 + Change in anion gap </li></ul></ul><ul><ul><li>>24 = metabolic alkalosis </li></ul></ul>
  16. 16. The Steps <ul><li>Start with the pH </li></ul><ul><li>Note the PCO 2 </li></ul><ul><li>Calculate anion gap </li></ul><ul><li>Determine compensation </li></ul>
  17. 17. Sample Problem #1 <ul><li>An ill-appearing alcoholic male presents with nausea and vomiting. </li></ul><ul><ul><li>ABG - 7.4 / 41 / 85 / 22 </li></ul></ul><ul><ul><li>Na- 137 / K- 3.8 / Cl- 90 / HCO 3 - 22 </li></ul></ul>
  18. 18. Sample Problem #1 <ul><li>Anion Gap = 137 - (90 + 22) = 25 </li></ul><ul><li>  anion gap metabolic acidosis </li></ul><ul><li>Winters Formula = 1.5(22) + 8  2 </li></ul><ul><li> = 39  2 </li></ul><ul><li>  compensated </li></ul><ul><li>Delta Gap = 25 - 10 = 15 </li></ul><ul><li>15 + 22 = 37 </li></ul><ul><li>  metabolic alkalosis </li></ul>
  19. 19. Sample Problem #2 <ul><li>22 year old female presents for attempted overdose. She has taken an unknown amount of Midol containing aspirin, cinnamedrine, and caffeine. On exam she is experiencing respiratory distress. </li></ul>
  20. 20. Sample Problem #2 <ul><li>ABG - 7.47 / 19 / 123 / 14 </li></ul><ul><li>Na- 145 / K- 3.6 / Cl- 109 / HCO 3 - 17 </li></ul><ul><li>ASA level - 38.2 mg/dL </li></ul>
  21. 21. Sample Problem #2 <ul><li>Anion Gap = 145 - (109 + 17) = 19 </li></ul><ul><li>  anion gap metabolic acidosis </li></ul><ul><li>Winters Formula = 1.5 (17) + 8  2 </li></ul><ul><li>= 34  2 </li></ul><ul><li>  uncompensated </li></ul><ul><li>Delta Gap = 19 - 10 = 9 </li></ul><ul><li>9 + 17 = 26 </li></ul><ul><li> no metabolic alkalosis </li></ul>
  22. 22. Sample Problem #3 <ul><li>47 year old male experienced crush injury at construction site. </li></ul><ul><li>ABG - 7.3 / 32 / 96 / 15 </li></ul><ul><li>Na- 135 / K-5 / Cl- 98 / HCO 3 - 15 / BUN- 38 / Cr- 1.7 </li></ul><ul><li>CK- 42, 346 </li></ul>
  23. 23. Sample Problem #3 <ul><li>Anion Gap = 135 - (98 + 15) = 22 </li></ul><ul><li> anion gap metabolic acidosis </li></ul><ul><li>Winters Formula = 1.5 (15) + 8  2 </li></ul><ul><li>= 30  2 </li></ul><ul><li>  compensated </li></ul><ul><li>Delta Gap = 22 - 10 = 12 </li></ul><ul><li>12 + 15 = 27 </li></ul><ul><li>  mild metabolic alkalosis </li></ul>
  24. 24. Sample Problem #4 <ul><li>1 month old male presents with projectile emesis x 2 days. </li></ul><ul><li>ABG - 7.49 / 40 / 98 / 30 </li></ul><ul><li>Na- 140 / K- 2.9 / Cl- 92 / HCO 3 - 32 </li></ul>
  25. 25. Sample Problem #4 <ul><li>Metabolic Alkalosis, hypochloremic </li></ul><ul><li>Winters Formula = 1.5 (30) + 8  2 </li></ul><ul><li>= 53  2 </li></ul><ul><li>  uncompensated </li></ul><ul><li> </li></ul>

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