Acid/base

Question 1

Metabolic acidosis

Answer 1

for every decrease in 1 mmol HCO3-, PCO2 decreases by 1.2

Question 2

Metabolic alkalosis

Answer 2

for every increase in 1 mmol HCO3-, PCO2 increases by 0.6

Question 3

Respiratory Acidosis

Answer 3

for every increase in 1 mm PCO2, HCO2- increases by O.4

Question 4

Respiratory Alkalosis

Answer 4

PCO2 < 35 mmHg
for every decrease in 1 mm PCO2, HCO3- decrease by 0.4, (for every 10 mm Hg the serum bicarb will decrease by 2 - 4.5 meq/L)

Question 5

Assessing presence of second acid-base disorder

Answer 5

Is the pH normal?
Which is the most abnormal value?
Adaptive response account for change in HCO3, and PCO2?
Is the anion gap increased? by how much? and is this accounted for?
Does the increase AG = the decrease in HCO3-

Question 6

Anion gap

Answer 6

Na - (Cl + HCO3-)

Question 7

Causes of increased AG acidosis

Answer 7

Endogenous: 
- Ketones - ketoacidosis
- Lactate - lactic acidosis
- Kidney failure (PO4 & other anions)
Exogenous: 
- Alcohols - ethylene glycol and methanol
- Salicylate overdose
- Toluene

Question 8

Normal (non) AG acidosis

UGA is positive (Na + K) - Cl = negative/impaired urinary NH4+

Answer 8

RTA (positive urine anion gap):

• low serum K+ –> check NH4+
  (a) (low - Type I - distal) urine pH > 5.5
  (b) (normal - Type II - proximal - glycosuria, phosphaturia, aminoaciduria) urine pH < 5.5
• high serum K+ - Type IV (hyporeninemic hypoaldosteronism)

Question 9

Normal (non) AG acidosis

UGA is negative (Na + K) - Cl = positive urinary NH4+

Answer 9

(Na + K) - Cl = negative Uosm - acidic urine

- GI losses

Question 10

Chloride unresponsive metabolic alkalosis

Answer 10

Excretion of Cl due to underlying physiology
UCl > 20 mEq/L
- Hyperaldosteronism, RAS, Cushings

Question 11

Chloride responsive metabolic alkalosis

Answer 11

Sparing of Cl excretion UCl < 10 mEq/L

• ECF volume contraction and hypokalemia due to various causes (vomiting, nasogastric suction, diuretics
• Saline solution to restore ECF volume can reverse alkalosis