pH

Question 1

simplified Henderson/Hassalbach

Answer 1

pH~(HCO3-/PaCO2)

Question 2

what is the signal for renal or respiratory compensation? what is the mechanism of compensation from kidneys? How effective is it? How long does it take?

Answer 2

changes in pH. Change the serum bicarb levels. The pH approaches but never reaches normal. Renal comp can take 3 days

Question 3

When do you think of respiratory acidosis or alkalosis

Answer 3

when pH and PaCO2 are on opposite sides of normal

Question 4

In respiratory acid/alkal what is the relationship b/w change in pH and PaCO2? Serum bicarb?

Answer 4

10mmHg PaCO2 corresponds to 0.8 pH change. Minimal change of bicarb in same direction as CO2

Question 5

what is a normal pH/PCO2 (bicarb)?

Answer 5

7.40/40 (24)

Question 6

what findings suggest metabolic acidosis? metabolic alkalosis?

Answer 6

• pH and PaCO2 down. Low serum bicarb.

- the opposite

Question 7

Compensatory respiration for metabolic acidosis and alkalosis: mechanism, what’s normal

Answer 7

hyperventilation and hypovent. Expected compensation occurs when last two digits of pH ~ PaCO2.

Question 8

Winters formula

Answer 8

• for determining appropriate respiratory compensation to met. acid.
• PaCO2=1.5*bicarb+8 plus or minus 2

Question 9

What are the two causes for metabolic acidosis?

Answer 9

acid accumulation or loss of bicarb

Question 10

What causes acid add-on states? How does increase in acid correspond to decrease in bicarb?

Answer 10

1meq:1meq. MUD PILES: Methanol, uremai, diabetic ketoacidosis, propylene glycol, isoniazid, lactic acidosis, ethylene glycol, salicylates.

Question 11

what is the normal anion gap? how is it calculated? what is abnormal? what is abnormality suggestive of?

Answer 11

Na-Cl-HCO3=12. If it’s >20 think metabolic acidosis due to acid accumulation

Question 12

Metabolic acidosis due to bicarb loss

Answer 12

aka hyperchloremic met acid. AG does not increase therefore Cl must increase. USED CARS: uretero-enterostomy, saline administration, endocrine disorders, diarrhea, carbonic anhydrase inhibitors, ammonium chloride, renal tubular acidosis, spironolactone

Question 13

metabolic alkalosis

Answer 13

due to elevated serum bicarb with compensatory hypoventilation. Two types: chloride responsive and unresponsive

Question 14

Chloride responsive met alk

Answer 14

decreased extracellular volume. eg, vomiting with volume depletion. Volume>pH. Want to absorb NaCl for water retention but Cl depleted so resorb NaCO3

Question 15

chloride unresponsive met alk

Answer 15

too much aldosterone

Question 16

delta delta analysis

Answer 16

delta anion gap should equal delta bicarb. most helpful when AG is elevated

Question 17

serum bicarb low in deltadelta

Answer 17

concurrent bicarb wasting condition (non elevated AG met acid)

Question 18

serum bicarb elevation in deltadelta

Answer 18

concurrent bicarb excess state (met. alk)