Acid Base Disorders Flashcards by Sarah Muse

What does pH represent

concentration of free hydrogen ions in circulation

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What is normal human pH

7.4

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What is an acid

a molecule that releases hydrogen ions in solution

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What is a base

any substance that can accept a hydrogen ion

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How are acids eliminated from the body?

pulmonary excretion of Co2
metabolic utilization
renal excretion of non volatile acids

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How does the body become acidic

excess CO2 drives the circulation rxn to the right–> increase in H+ ions

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How does the body become alkalotic

excess HCO3- drives circulation rxn to the left–> decrease in H+ ions

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What is the equilibrium reaction

CO2+H2O=H2CO3=HCO3-+H+

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When do you gain hydrogen ions

increased CO2
production of phosphoric and sulfuric acid
loss of bicarb from GI (diarrhea)
loss of bicarb in urine

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What causes a loss of hydrogen ions

emesis

- urine

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What are common causes of metabolic acidosis

excess production of lactic acid
formation of ketone bodies
loss of bicarb

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What causes respiratory acidosis

hypoventilation or respiratory disease can result in retention of CO2

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What causes respiratory alkalosis

hyperventilation–>blowing off CO2

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What is the anion gap

difference between the plasma concentration of the major measure cation (Na) adn the sume of measured anions (Cl and HCO3)

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What things can produce excess lactic acid

severe exercise
seizure
shock/hypoxia

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What things can form ketone bodies in the body

uncontrolled DM

- fasting states

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What does the anion gap represent

the concentration of unmeasured anions like phosphates, sulfates, organic acids and proteins

What is the normla AG

8-16 mEq/L

What is the AG equation

AG= Na- {Cl+HCO3]

What does a normal anion gap tell you in metabolic acidosis

excessive bicarbonate loss

What causes of metabolic acidosis would show a normal anion gap

diarrhea
small bowel, pancreatic or biliary fistula drainage
ileostomy drainage
renal tubular acidosis

What does an elevated anion gap in metabolic acidosis tell you

excess metabolic acid production

What causes of metabolic acidosis would show an elevated anion gap

lactic acidosis
DKA
alcoholic ketoacidosis
starvation ketoacidosis
poisoning of toxic alcohols
kidney dysfuntion

What is the most common cause of metabolic acidosis in a hospitalized patient

lactic acidosis

What is the cause of type A lactic acidosis

hypoxia--> decreased tissue perfusion--> LA production

What types of things cause type A lactic acidosis

- cardiogenic, septic, hemorrhagic shock - carbon monoxide poisoning - cyanide poisoning

Is type A or type B lactic acidosis more common

type A

What causes type B lactic acidosis

impaired cellular metabolism or tissue ischemia without systemic hypoperfusion

What things can cause type B lactic acidosis

- DKA - alcoholism - infection - malignancy - metformin - bowel necrosis

Mnemonic for AG metabolic acidosis

"MUDPILES" ``` Methanol Uremia DKA Propylene glycol Isoniazid Lactic acidosis Ethylene glycol and ethanol Salicylates and starvation ```

How do you treat metabolic acidosis

- treat underlying cause | - IV or oral bicarb if severe

What can cause metabolic alkalosis

- ingestion or administration of alkali - stomach loss of H+ - renal loss of H+ - diuretic use (contraction alkalosis)

What are the two theories behind contraction alkalosis

#1- loss of large volume of bicarb free fluid #2- renal compensation for volume loss increases renin--> angiotensin II--> increase aldosterone-->decrease in K

What is milk alkali syndrome

when a person consumes excessive amounts of milk along with alkaline antacids

Why does milk alkali syndrome occur

hypercalcemia reduces the glomerular filtration rate which increases bicarb reabsorption

How do you know if an acid base disorder is cause by a respiratory problem

primary defect in a change in pCO2

How do you know if an acid base disorder is due to a metabolic problem

primary defect is change in HCO3

How do the kidneys respond to acidosis

- bicarb binds H+ - additional H+ are excreted bound to other buffers (hydrogen phosphate) - new bicarb is formed during tubular glutamine metabolism

How do the kidneys respond to alkalosis

- H+ binds bicarb - bicarb is excreted in the urine - tubular glutamine metabolism is decreased to lower bicarb productio

H+, HCO3-, CO2 change in... respiratory acidosis respiratory alkalosis metabolic acidosis metabolic alkalosis

``` Resp acidosis- everything increase Resp alk- everything decreased Met acidosis- increased H+ decreased HCO3/CO2 Met alkolosis- decreased H increased HCO3/CO2 ```

Appropriate HCO3 and PCO2 compensation for... ``` metabolic acidosis metabolic alkalosis acute resp acidosis chronic resp acidosis acute resp alkalosis chronic resp alkalosis ``` FYI

metabolic acidosis- HCO3 dec by 1 PCO2 dec by 1.2 metabolic alkalosis- HCO3 dec by 1 PCO2 dec by 0.4-0.7 A. resp acidosis- pCO2 inc by 10 HCO3 inc by 1-2 C. resp acidosis pCO2 inc by 10 HCO3 inc by 3.5 A. resp alkalosis pCO2 dec by 10 HCO3 dec by 1-2 C. resp alkalosis pCO2 dec by 10 HCO3 dec by 5

What are the steps for determining ABGs

1: acidosis or alkalosis 2: is compensation appropiate? 3: check anion gap