1 / 25

Arterial Blood Gas Analysis

Arterial Blood Gas Analysis. What is an ABG?. The Components pH / PaCO 2 / PaO 2 / HCO 3 / O 2 sat / BE Desired Ranges pH - 7.35 - 7.45 PaCO 2 - 35-45 mmHg PaO 2 - 80-100 mmHg HCO 3 - 21-27 O 2 sat - 95-100% Base Excess - +/-2 mEq/L. Why Order an ABG?.

haru
Download Presentation

Arterial Blood Gas Analysis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Arterial Blood Gas Analysis

  2. What is an ABG? • The Components • pH / PaCO2 / PaO2 / HCO3 / O2sat / BE • Desired Ranges • pH - 7.35 - 7.45 • PaCO2 - 35-45 mmHg • PaO2 - 80-100 mmHg • HCO3 - 21-27 • O2sat - 95-100% • Base Excess - +/-2 mEq/L

  3. Why Order an ABG? • Aids in establishing a diagnosis • Helps guide treatment plan • Aids in ventilator management • Improvement in acid/base management allows for optimal function of medications • Acid/base status may alter electrolyte levels critical to patient status/care

  4. Logistics • When to order an arterial line -- • Need for continuous BP monitoring • Need for multiple ABGs • Where to place -- the options • Radial • Femoral • Brachial • Dorsalis Pedis • Axillary

  5. Acid Base Balance • The body produces acids daily • 15,000 mmol CO2 • 50-100 mEq Nonvolatile acids • The lungs and kidneys attempt to maintain balance

  6. Acid Base Balance • Assessment of status via bicarbonate-carbon dioxide buffer system • CO2 + H2O <--> H2CO3 <--> HCO3- + H+ • ph = 6.10 + log ([HCO3] / [0.03 x PCO2])

  7. The Terms • ACIDS • Acidemia • Acidosis • Respiratory ↑CO2 • Metabolic ↓HCO3 • BASES • Alkalemia • Alkalosis • Respiratory • ↓CO2 • Metabolic • ↑HCO3

  8. Respiratory Acidosis • ↓ph, ↑CO2, ↓Ventilation • Causes • CNS depression • Pleural disease • COPD/ARDS • Musculoskeletal disorders • Compensation for metabolic alkalosis

  9. Respiratory Acidosis • Acute vs Chronic • Acute - little kidney involvement. Buffering via titration via Hb for example • pH ↓by 0.08 for 10mmHg ↑ in CO2 • Chronic - Renal compensation via synthesis and retention of HCO3 (↓Cl to balance charges Ü hypochloremia) • pH ↓by 0.03 for 10mmHg ↑in CO2

  10. Respiratory Alkalosis • ↑pH, ↓CO2, ↑Ventilation • ↓ CO2Ü ↓ HCO3 (↑Cl to balance charges Ü hyperchloremia) • Causes • Intracerebral hemorrhage • Salicylate and Progesterone drug usage • Anxiety Ü ↓lung compliance • Cirrhosis of the liver • Sepsis

  11. Respiratory Alkalosis • Acute vs. Chronic • Acute - ↓HCO3 by 2 mEq/L for every 10mmHg ↓ in PCO2 • Chronic - Ratio increases to 4 mEq/L of HCO3 for every 10mmHg ↓ in PCO2 • Decreased bicarb reabsorption and decreased ammonium excretion to normalize pH

  12. Metabolic Acidosis • ↓pH, ↓HCO3 • 12-24 hours for complete activation of respiratory compensation • ↓PCO2 by 1.2mmHg for every 1 mEq/L ↓HCO3 • The degree of compensation is assessed via the Winter’s Formula Ü PCO2 = 1.5(HCO3) +8 ± 2

  13. The Causes • Metabolic Gap Acidosis • M - Methanol • U - Uremia • D - DKA • P - Paraldehyde • I - INH • L - Lactic Acidosis • E - Ehylene Glycol • S - Salicylate • Non Gap Metabolic Acidosis • Hyperalimentation • Acetazolamide • RTA (Calculate urine anion gap) • Diarrhea • Pancreatic Fistula

  14. Metabolic Alkalosis • ↑pH, ↑HCO3 • ↑PCO2 by 0.7 for every 1mEq/L ↑ in HCO3 • Causes • Vomiting • Diuretics • Chronic diarrhea • Hypokalemia • Renal Failure

  15. Mixed Acid-Base Disorders • Patients may have two or more acid-base disorders at one time • Delta Gap Delta HCO3 = HCO3 + Change in anion gap >24 = metabolic alkalosis

  16. The Steps • Start with the pH • Note the PCO2 • Calculate anion gap • Determine compensation

  17. Sample Problem #1 • An ill-appearing alcoholic male presents with nausea and vomiting. • ABG - 7.4 / 41 / 85 / 22 • Na- 137 / K- 3.8 / Cl- 90 / HCO3- 22

  18. Sample Problem #1 • Anion Gap = 137 - (90 + 22) = 25 Ü anion gap metabolic acidosis • Winters Formula = 1.5(22) + 8 ± 2 = 39 ± 2 Ü compensated • Delta Gap = 25 - 10 = 15 15 + 22 = 37 Ü metabolic alkalosis

  19. Sample Problem #2 • 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.

  20. Sample Problem #2 • ABG - 7.47 / 19 / 123 / 14 • Na- 145 / K- 3.6 / Cl- 109 / HCO3- 17 • ASA level - 38.2 mg/dL

  21. Sample Problem #2 • Anion Gap = 145 - (109 + 17) = 19 Ü anion gap metabolic acidosis • Winters Formula = 1.5 (17) + 8 ± 2 = 34 ± 2 Ü uncompensated • Delta Gap = 19 - 10 = 9 9 + 17 = 26 Ü no metabolic alkalosis

  22. Sample Problem #3 • 47 year old male experienced crush injury at construction site. • ABG - 7.3 / 32 / 96 / 15 • Na- 135 / K-5 / Cl- 98 / HCO3- 15 / BUN- 38 / Cr- 1.7 • CK- 42, 346

  23. Sample Problem #3 • Anion Gap = 135 - (98 + 15) = 22 Ü anion gap metabolic acidosis • Winters Formula = 1.5 (15) + 8 ± 2 = 30 ± 2 Ü compensated • Delta Gap = 22 - 10 = 12 12 + 15 = 27 Ü mild metabolic alkalosis

  24. Sample Problem #4 • 1 month old male presents with projectile emesis x 2 days. • ABG - 7.49 / 40 / 98 / 30 • Na- 140 / K- 2.9 / Cl- 92 / HCO3- 32

  25. Sample Problem #4 • Metabolic Alkalosis, hypochloremic • Winters Formula = 1.5 (30) + 8 ± 2 = 53 ± 2 Ü uncompensated

More Related