Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.
-
Upload
sharyl-sullivan -
Category
Documents
-
view
225 -
download
0
Transcript of Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.
![Page 1: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/1.jpg)
Acid-Base Disorders
A Simple Approach
BP Kavanagh, HSC
![Page 2: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/2.jpg)
1st Step
Check the ABG result or validity:
[H] nM = [PaCO2] 24/[HCO3-]
In range : 7.25 - 7.55,
pH = 7.X
[80-X] = approx. [H] nM
![Page 3: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/3.jpg)
Normal Values• pH 7.35 - 7.45
• PaCO2 35 - 45 mmHg
• [HCO3-] 22 - 26 mmol.L-1
• Anion Gap 10-14 mmol.L -1 [Assumes Protein 40 g/l - should reduce AG by 3, for every
10 g/l decrease in plasma protein]
![Page 4: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/4.jpg)
pH = 7.4
There is no acid-base disorder
OR
There are more than one, and they’re perfectly balanced, not compensated
[Q: How many types can co-exist?]
![Page 5: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/5.jpg)
HypoventilationBrain InjuryCNS Depressants
MyoneuralChest WallLung ParenchymaAirwaysMechanical Ventilation
Brain
Lung
![Page 6: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/6.jpg)
HyperventilationAnxietyDrugsEncephalopathyPregnancy
Mechanical VentilationPulmonary FibrosisPulmonary Edema
Brain
Lung
![Page 7: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/7.jpg)
Ventilation
Alv. vent. = min. vent. - dead space vent
= [f.VT] - [f.VD]
= f.[VT - VD]
= [f / VT].[1 - VD / VT]
• Frequency• Tidal Volume• Physiologic Deadspace
![Page 8: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/8.jpg)
Anion Gap
No Osmole GapKetonesLactateUremiaASA/ParaldehydeRhabdomyolysis
Osmole GapMethanolEthylene GlycolEthanol
![Page 9: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/9.jpg)
Non-Anion Gap
Dilution of HCO3-
Normal SalineTPN
Loss of HCO3-
GI LossRenal Loss
![Page 10: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/10.jpg)
Diarrhea
Ureteric Diversion[Cl- exchanged for HCO3
-]
GI Loss of HCO3-
![Page 11: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/11.jpg)
Renal Loss of HCO3-
1. RTA
2. Acetazolamide
3. Steroid Deficiency
![Page 12: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/12.jpg)
ECF Expansion
HCO3-
Cl- NS
TPN
HCO3-
Cl-
ECF Vol.
Cl- mmol.
HCO3- mmol.
Cl- conc.
HCO3- conc.
![Page 13: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/13.jpg)
Metabolic Alkalosis - CausesECF Contracted [Ur Cl- < 10] Remote Diuretics [ECF low, but no current Cl- spill]
Gastric Losses [Aspiration or Vomiting]
ECF Normal or Expanded [Ur Cl- > 20]
Current Diuretics
Excess Steroid Effect
Excess Renin Effect
Bartters Syndrome
Administration of HCO3-
Post Hypercapnia [Ur Cl- < 10]
![Page 14: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/14.jpg)
ECF Contraction
HCO3-
Cl- Diuresis
HCO3-
Cl-
ECF Vol.
Cl- mmol.
HCO3- mmol.
Cl- conc.
HCO3- conc.
[Secondary Hyperaldo.]
Cl-
![Page 15: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/15.jpg)
2nd Step
• What's the pH, PaCO2, & the HCO3- ?
• If the pH is > 7.45,
there's a primary alkalosis
• If the pH is < 7.35,
there's a primary acidosis
![Page 16: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/16.jpg)
3rd Step
• Calculate the Anion Gap
• If > 20, Calculate Anion Gap ‘Excess’
• Add the ‘Excess’ to the Bicarbonate
![Page 17: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/17.jpg)
The Anion GapIf assess a patient for all known causes of
an anion gap:
AG [mmol/l] % Confirmed
15 30
20 75
25 95
![Page 18: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/18.jpg)
Anion Gap Rules1 If > 20, there’s likely a cause to find
2 AG does not rise to compensate
3 Changes in AG should be matched with changes in HCO3
- [titrated, mole for mole]
![Page 19: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/19.jpg)
If AG is increased > 201. Assume it began normal [12 mmol/l]
2. Therefore an excess has developed
3. Assume the HCO3- began normal
4. If [HCO3- + xs] < normal HCO3
-
additional primary loss of HCO3-
5. If [HCO3- + AGxs] > normal HCO3
-
additional primary source of HCO3
-
![Page 20: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/20.jpg)
Primary AG Metabolic Acidosis Only
Na+
Cl-
AG
HCO3-
Cl-
AG
HCO3-
AG xs
Before After
![Page 21: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/21.jpg)
Primary AG Metabolic Acidosis, WithPrimary Non-Gap Metabolic Acidosis
Na+
Cl-
AG
HCO3-
Cl-
AG
HCO3-
AG xs
Before After
![Page 22: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/22.jpg)
Primary AG Metabolic Acidosis, WithPrimary Metabolic Alkalosis
Na+
Cl-
AG
HCO3-
Cl-
AG
HCO3-
AG xs
Before After
![Page 23: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/23.jpg)
Summary Steps1. Clinical Status
2. Verify Results
3. Determine the Primary Problem[pH, PaCO2, HCO3
-]
4. Calculate AG
5. If AG > 20, calculate AG excess
6. Add to HCO3- [compare to normal range]
![Page 24: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/24.jpg)
Case #1• pH 7.5• PaCO2 29
• HCO3- 24
Case #2• pH 7.2• PaCO2 70
• HCO3- 25
![Page 25: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/25.jpg)
Case #3• pH 7.55• PaCO2 40
• HCO3- 38
Case #4• pH 7.34• PaCO2 60
• HCO3- 31
![Page 26: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/26.jpg)
Case #6
• pH 7.5• PaCO2 20
• HCO3- 15
• Na+ 140• Cl- 103
![Page 27: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/27.jpg)
Case #7
• pH 7.4• PaCO2 40
• HCO3- 24
• Na+ 145• Cl- 100
![Page 28: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/28.jpg)
Case #8
• pH 7.5• PaCO2 20
• HCO3- 15
• Na+ 145• Cl- 100
![Page 29: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/29.jpg)
Case #9
• pH 7.1• PaCO2 50
• HCO3- 15
• Na+ 145• Cl- 100
![Page 30: Acid-Base Disorders A Simple Approach BP Kavanagh, HSC.](https://reader030.fdocuments.us/reader030/viewer/2022033022/56649cd65503460f9499e448/html5/thumbnails/30.jpg)
Case #10
• pH 7.15• PaCO2 15
• HCO3- 5
• Na+ 140• Cl- 110