05.07 - Acid Base (Wall) - PP + Handout, No reading, Not watched Flashcards by Ryan Lee

Expected HCO3, pCO2 changes for Acute Respiratory Alkalosis

HCO3 decreases 2 mEq for each 10 mm decrease in pCO2

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Type 1 (Distal) RTA is caused by __ and causes ___

Defective H-ATPase, decreased acid secretion

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Metabolic Acidosis is ___ Bicarb

Decreased

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For simple acid-base disorders, pC02 and HCO3 always

change in same direction

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Acid Base disorder caused by Hyperaldosteronism

Metabolic Alkalosis

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2 disorders with elevated Bicarb (>30)

Metabolic Alkalosis and Chronic Respiratory Acidosis (with kidney compensation)

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How does plasma anion gap change with respiratory disorders

Doesn’t

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Urine anion gap is an indirect estimate of

Urinary NH4+ excretion

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__ % of Bicarb is reabsorbed in PT via __

90% via Na-H antiporter (Na is driving force)

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Why is Citrate given in acid base

Metabolized to Bicarb

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Normal Urine Anion Gap

Positive, 10 mEq/L

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If PAG is normal in Metabolic acidosis

Might be kidney not making NH4+, or Losing Bicarb by Diarrhea

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Why can you tell the difference b/t acute and chronic respiratory disorders

Takes kidneys hours to days to compensate

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What inhibits Na channel in principal cell of cortical collecting duct?

Amiloride, Triamterene

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Isohydric principle

All buffers change in same direction

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Metabolic Alkalosis is ___ Bicarb

Increased

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What must accompany NH4+ in urine

Chloride

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What is synonymous with send a bicarb into blood

Proton pumped into urine that came from intracellular Carbonic Anhydrase

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How does renal failure affect acid base balance

Reduced GFR - Decreased Ammonium excretion

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What is invariably present in Simple Acid-Base disorders

Compensation

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pH and H+ ranges

6.8-7.8; 16-160 neq/L

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When A- from HA is excreted into urine

Normal Plasma Anion gap, increased plasma chloride

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Anion Gap if you lose Bicarb directly in stool

None b/c there’s no unmeasured anion

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Etiology of Metabolic Alkalosis

Loss of H+ into GI or into urine

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Respiratory Acidosis is __ CO2

Increased CO2

What must be present in simple acid-base disorders

Secondary physiologic compensation

When will you have lower or negative UAG

If you've lost bicarb by diarrhea, ammonium increases in urine, and chloride accompanies it

Major extracellular buffer

Bicarb

If Na concentration stays constant, but Chloride conc. changes, then

an acid base disorder is present

What acid base disorder can dietary protein intake cause

Acidosis

What puts bicarb back into urine

Cl/Bicarb (Pendrin) in beta-intercalated cells

Cl responsive in Metabolic Alkalosis means

Urine Cl

Patient with lower GFR develops more severe acidosis following acid load b/c

can't secrete NH4+ as well

Expected pH changes for Chronic Respiratory Acidosis

HCO3 increases 4 mEq for each 10 mm increase in pCO2

Timeframe of H+ excretion, Bicarb reabsorption, and Bicarb generation

Hours to days

Expected pH Changes for Acute Respiratory Acidosis

HCO3 increases 1 mEq for each 10 mm increase in pCO2

Type 4 (Hypoaldosteronism) RTA is caused by ___ and causes \_\_\_

Impaired proton and K secretion, decreased acid secretion

What drug inhibits sodium bicarb reabsorption in proximal tubule

Acetazolamide (CAi)

Speed and effectiveness of 2 buffering routes in respiratory acidosis

(1) Plasma: rapid but limited, 1-2 mEq/L increase in Bicarb; (2) Kidney excretes NH4, generating new bicarb, delayed 2-3 days

Acid Base disorder caused by Loop or Thiazides

Metabolic Alkalosis

How long does it take kidney to generate new bicarb ions

2-3 days

Bicarb transporter in beta-intercalated cells

Cl/Bicarb (Pendrin)

Normal HCO3-

22-26 (24mEq/L)

Acute Respiratory acid base disorders always have __ change in pH than chronic b/c \_\_

Greater change, b/c kidney is slow in compensating

Changes in HCO3 and pCO2 in Metabolic Alkalosis

Both increase

Changes in HCO3 and pCO2 in Respiratory Acidosis

Both increase

How does CO2 in alpha-intercalated cells affect H secretion/reabsorption

CO2 binds with OH- to form bicarb that is reabsorbed instead of secreted; H+ is the secreted instead of bonding with the OH-

When A- from HA is reabsorbed by kidney or retained in plasma

Unmeasured Anion - Increased Plasma Anion Gap, minimal change in plasma Chloride

HCO3 in Respiratory Alkalosis

Slightly decreased

If PAG increases in metabolic acidosis, it's

Lactic Acidosis or some other renally conserved acid anion

How does plasma Na change with acid base disorders

Doesn't

Where is Bicarb primarily reabsorbed

PT and LOH

Cl resistance in Metabolic Alkalosis means

Urine Cl \>20 mEq/L (usually \>50 mEq/L)

Urine Anion Gap =

Na + K - Cl (in urine)

Primary acid we produce

CO2 from metabolism of fats and carbs

Timeframe of intracellular fluid buffer systems

2-4 hours

Which RTA results from Decreased Acid Excretion?

Type 1 (Distal) and Type 4 (Hypoaldosteronism)

Every proton proton pumped into the urin had to come from

Intracellular Carbonic Anhydrase

Most common form of chronic alkalosis where the kidney compensates

Pregnancy - Alkalemic

2 major buffers of urine

NH4+ and Phosphate

Pregnant women acid base

Slightly Alkalemic

Changes in HCO3 and pCO2 in Respiratory Alkalosis

Both decrease

Decreased Acid excretion is synonymous with

Impaired NH4+ excretion

Trick for converting [H+] to pH

80 - decimal digits of pH

How to distinguish b/t Acute and Chronic

Look at Bicarb: Small change (1-2), then acute; Larger change (4-5) then kidney has compensated and chronic

pKa of Bicarb

6.1

Normal pCO2

36-44 (40mmHg)

Diarrhea results in loss of

Bicarb --\> Metabolic Acidosis

Acid Base Disorder caused by Hypokalemia

Metabolic Alkalosis

Final excretion of daily aci load occurs primarily in

Where are non-Carbonic acids eliminated?

Combined with buffers and secreted by kidneys

Indirect estimate of urinary NH4+ excretion

Urine Anion Gap

Why is NH4+ trapped in urinary lumen

Lipid soluble

Expected pH changes for Chronic Respiratory Alkalosis

HCO3 decreases 5 mEq for each 10 mm decrease in pCO2

Compensation for Respiratory disorders occurs by

Alterations in Bicarb concentration

Normal Plasma Bicarb

24 mEq/L

In simple acid-base disorders, the compensatory mechanisms

Must be present, Never fully correct pH

Respiratory Alkalosis is __ CO2

Decreased CO2

Metabolic Disorders are processes that directly alter

Bicarb Concentration

Urine AG becomes less positve/more negative with

Increasing urinary NH4+ --\> Cl must accompany NH4+

How to get Bicarb from Total CO2

Subtract 1-1.5

How does plasma Cl change with plasma HCO3

Changes equally and inversely

How much does Total CO2 exceed plasma bicarb?

By 1-1.5 mEq/L

Plasma Cl is altered in which Acid Base Disorders

All except increased Plasma AG Metabolic Acidosis

pH of 7.4 = what [H]

40 nEq/L

Action of Acetazolamide

CA inhibitor - Inhibits Na Bicarb reabsorption in PT

How does low pH alon drive bicarb reabsorption

More CO2 in blood freely enters tubular cell - Meaning more reactant to form H+ that goes into Na-H Antiporter

Changes in HCO3 and pCO2 in Metabolic Acidosis

Decrease in HCO3- and pCO2

[H+] =

24 x pCO2 / [HCO3]

HCO3 in Respiratory Acidosis

Slightly increased

Only caveat to Urine Chloride in Metabolic Alkalosis

If just took Loop diuretic, urine Cl can't be low b/c block reabsorption

Why is Isohydric principle useful

If we know what Bicarb is doing, we know what others are doing (all change in same direction)

Acid Base Cells in Collecting Duct

Intercalated cells

Where is Carbonic Acid eliminated?

Lungs

Which RTA results from Loss of Bicarb

Type 2 (Proximal) RTA

Respiratory compensation vs Metabolic Compensation

Respiratory compensations is rapid; Metabolic compensation (by kidneys) is slower over 1-2 days

3 Etiology Categories of Metabolic Acidosis

Decreased Renal Acid Excretion; Direct Bicarb Losses; Increased Acid Generation

Total CO2 concentration =

Dissolved CO2 + Bicarbonate concentration in venous sample; 25-26 mEq/L

Normal Chloride

105

05.07 - Acid Base (Wall) - PP + Handout, No reading, Not watched Flashcards

(99 cards)