1. Arash Safaie, MD Emergency Physician

2.   pH  ↓7.36: Acidemia  ↑7.44: Alkalemia  Physiologic Buffers  Bicarbonate  Carbonic Acid Systems (RBCs)  Phosphate Buffers (Bone) Basic Concepts

3.  Useful Knowledge ABG vs. VBG  VBG  pH: 0.03↓  PCO2: 6.6↑  HCO3: 1.4↑ Role of Temperature Tempe rature (°C) pH Paco 2 (mm Hg) Pao 2 (mm Hg) 207.651927 307.503051 357.433770 377.404080 397.374491

4.   Acute  Intracellular Buffering  CO2 Narcosis  ↑PCO2: 10  ↑HCO3: 1  ↑PCO2: 10  ↓pH: 0.08  Chronic  Beyond 6-12h starts  5d completes  Hypochloremia  ↑PCO2: 10  ↑HCO3: 4  ↑PCO2: 10  ↓pH: 0.03 Respiratory Acidosis

5.   Acute  Intracellular Buffering  ↓PCO2: 10  ↓HCO3: 2  ↓PCO2: 10  ↑pH: 0.08  Chronic  Beyond 6-36h starts  14d completes  Hyperchloremia  ↓PCO2: 10  ↓HCO3: 3.5  ↓PCO2: 10  ↑pH: 0.03 Respiratory Alkalosis

6.   Pregnancy  pH: 7.46-7.50  PaCO2: 31-35  HCO3: 18-22  Childhood (7-19y)  PaCO2: 37 Pregnancy & Childhood

7.   Compensation  ↓HCO3: 1  ↓PCO2: 1.2  PCO2: (1.5 x HCo3) + 8  12-24h for Max. Respiratory Response  Compensation Limit  PCO2: 10-15  Normal AG  Urine AG: (Urine Na + Urine K) – Urine Cl  Positive Urine AG: Altered Urinary Acidification  Negative Urine AG: GI Loss  Role of NaHCO3 in Rx Metabolic Acidosis

8.   AG: Na – (Cl + HCO3)  > 15 High  < 3 Low  Δ G: (AG – 12) – (24 – HCO3)  >+6: concurrent Metabolic Alkalosis or Respiratory Acidosis  <-6: concurrent Normal AG Metabolic Acidosis or Respiratory Alkalosis Anion Gap & Δ Gap

9.   Compensation  ↑HCO3: 1  ↓PCO2: 1.2  Compensation Limit  PCO2: 55-75  Saline Responsiveness  Saline-Responsive: Urine Cl <10  Saline-Resistant: Urine Cl >10  Rx  Saline-Responsive: NaCl + KCl  Severe: IV Mineral Acids  Edematous: Acetazolamide, Dialysis  Saline-Resistant: KCl + Mineralocorticoid Antagonist Metabolic Alkalosis

11.   pH:7.37  PCO2:50  HCO3:28  Na:139  Cl:102 1

12.   pH:7.44  PCO2:46  HCO3:34  Na:140  Cl:100 2

13.   pH:7.35  PCO2:28  HCO3:14  Na:140  Cl:110 3

14.   pH:7.32  PCO2:50  HCO3:25  Na:140  Cl:110 4

15.   pH:7.43  PCO2:30  HCO3:22  Na:140  Cl:108 5

16.   pH:7.30  PCO2:40  HCO3:20  Na:140  Cl:110 6

17.   pH:7.37  PCO2:16  HCO3:4  Na:140  Cl:96 7

18.   pH:7.30  PCO2:16  HCO3:4  Na:140  Cl:106 8

19.   pH:7.30  PCO2:28  HCO3:14  Na:140  Cl:111 9

20.   pH:7.42  PCO2:50  HCO3:29  Na:140  Cl:105 10