Arterial blood gases cases with interpretation.pptx

Review of arterial blood gases cases and reports

1. ABG CASES EXAMPLES Lecturer: RCS. Lway Al- Ahdal

2. Step 1: Assess ABG Validity Henderseon-Hasselbach equation: [H+] = 24 × (PaCO2) [HCO3-]

3. Step 2: Is there ’ s acidemia or alkalemia? * Look at the pH : < 7.35 :ACIDOSIS > 7.45 :ALKALOSIS 7.35 – 7.45 : normal/mixed disorder

4. Step 3: Assess the primary disturbance? Is it respiratory or metabolic? R espi r a t o r y Acidosis pH ↓ PaCO 2 ↑ R espi r a t o r y Alkalosis pH ↑ PaCO 2 ↓ M e t abol i c Acidosis pH ↓ H C O 3 ↓ M e t abol i c Alkalosis pH ↑ HCO 3 ↑

5. Step 4: Is there’s appropriate compensation for the primary disturbance? Respiratory acidosis chronic HCO3= 3.5 X (PaCO2 - 40/ 10) Acute HCO3 = ({PaCO2 - 40}/ 10) ± 3 Respiratory alkalosis Chronic HCO3= 5 X (40 - PaCO2/10) Acute HCO3= 5 X (40 - PaCO2/10) Metabolic alkalosis PaCO2 = [0.7 x (rise in HCO3) +40] Metabolic acidosis PaCO2 = ({1.5 × HCO3 )+ 8} ± 2

6. Step 5: Calculate the anion gap if there ’ s metabolic acidosis? a nd the delta ratio if there ’ s high anion gap i s present AG = [Na+] - ( [Cl-] + [HCO3-] ) ∆ Gap =  

7. Case 1 A 75 year old gentleman living in the community is being assessed for home oxygen. His ABG is as follows: pH: 7.36 pO2: 70 % pCO2: 57 mmHg HCO3: 31 BE: +5

8. What does the ABG demonstrate? This is a compensated respiratory acidosis. Rather it reflects a compensation for a chronic respiratory acidosis secondary to chronic pulmonary disease. Note this is an acidosis, not an acidaemia (pH normal, but only due to compensatory mechanisms: the high bicarbonate).

9. Case 2 A 64 year old gentleman with a history of COPD presents with worsening shortness of breath and increased sputum production pH: 7.21 pO2: 7.2 (10–14) pCO2: 64 mmHg HCO3: 29 BE: +4

10. What does the ABG show? This is Type 2 respiratory failure. Note that the HCO3 is raised in this patient despite the abnormal pH. With the above history this is likely to represent an acute on chronic respiratory acidosis. This would indicate that the patient normally retains CO2 and has a chronically raised HCO3.

11. Case 3 A 21 year-old woman presents feeling acutely lightheaded and short of breath. She has her final university exams next week. pH: 7.48 pO2: 104 mmHg pCO2: 26.5 mmHg HCO3: 22 BE: +2

12. What does this ABG show and what is the differential diagnosis? T his is a respiratory alkalaemia * Differential diagnosis: Hypermetabolic states (e.g. infection or fever) Pain Anxiety hyperventilation

13. Case 4 A 32 year-old man presents to the emergency department having been found collapsed by his girlfriend. pH: 7.25 pO2: 83 mmHg pCO2: 24 mmHg HCO3: 11 BE: -15 Potassium:4.5 Sodium: 135 Chloride: 100

14. What is the anion gap in this case? Anion gap = ([Na ] + [K ]) - ([Cl ] + [HCO ]) = 28.5 This is a raised anion gap metabolic acidosis. Common causes of HAGMA * Excess production of acids such as DKA, lactic acidosis * Ingestion of acids like Methanol, ethanol, ethylene glycol * Inability to clear acids like in Renal failure * Loss of bicarbonate : From the GI tract or from kidneys

15. Case 5 A woman is admitted to the hospital with salmonella enteritis and a history of severe diarrhea for about 10 days before admission. * Arterial Blood Gases pH 7.15 PaCO2 15 mm Hg [HCO3] 5 mEq /L PaO2 96 mm Hg SaO2 93% * Plasma Electrolytes Na+ = 134 mEq /L Cl− = 113 mEq /L K+ = 3.2 mEq /L

16. Interpretation * Partially compensated metabolic acidosis with normoxemia . * The anion gap is normal (14 mEq /L). * The plasma chloride concentration is high ( hyperchloremia ). * The probable cause of the hyperchloremic (normal anion gap) acidosis in this patient is the history of severe diarrhea.

17. Case 6 A 28-year-old woman in her eighth month of pregnancy is admitted to the hospital after having severe vomiting for several days. Arterial blood gases, and electrolytes are as follows: Arterial Blood Gases pH 7.58 PaCO2 31 mm Hg [HCO3] 28 mEq /L PaO2 65 mm Hg SaO2 96% Na+= 130 mEq /L Cl− = 86 mEq /L K+ = 3.1 mEq /L

18. Interpretation 1. Mixed respiratory and metabolic alkalosis with mild hypoxemia. 2. Severe vomiting can cause metabolic alkalosis. 3. Respiratory alkalosis and hyperventilation is common in the third trimester of pregnancy

19. Case 7 This 50-year-old patient was recently transferred to the intensive care unit from the emergency department after progressive cardiopulmonary distress that culminated in a cardiac arrest. The patient is presently intubated and receiving mechanical ventilation. Current arterial blood gases, are shown below: Arterial Blood Gases FIO2 0.7 pH 7.20 PaCO2 50 mm Hg [BE] −9 mEq /L PaO2 64 mm Hg SaO2 85% Na+= 140 mEq /L Cl = 105 mEq /L K+= 5.4 mEq /L

20. Case 8 A 17-year-old boy with a history of asthma has been continuously short of breath for approximately 2 days. He enters the hospital wheezing and with air hunger. Arterial blood gases are as follows: Arterial Blood Gases FIO2 0.21 pH 7.35 PaCO2 22 mm Hg [HCO3] 12 mEq /L PaO2 41 mm Hg SaO2 77%

21. Case 9 A 32-year-old woman with a history of diabetes mellitus is admitted to the hospital with lethargy and confusion. Current arterial blood gases are shown below: Arterial Blood Gases FIO2 0.21 pH 7.04 PaCO2 15 mm Hg [HCO3] 10 mEq /L PaO2 125 mm Hg SaO2 95% Na+ =136 mEq /L Cl− = 95 mEq /L K+ = 6.3 mEq /L

22. Great Done