2. Approach to Acid Base

Question 1

What is the following equation?

pH= 6.1 + log ( HCO3/ (.03x PCO2) )

Answer 1

Henderson-Hasselbalch Equation

Question 2

When there is an increase in HCO3 or a increase in PCO2, what occurs to blood pH?

Answer 2

Inc HCO3 = increase pH

Inc PCO2 = decrease pH

Question 3

CO2 + H20 —> H2CO3 —> H+ + HCO3

Answer 3

Meow

Question 4

Lungs regulate pH by respiration rate, if increased RR = increased CO2 blown off = ?

Answer 4

Increase in pH

Question 5

Match the following:
Metabolic acidosis
Metabolic aklalosis
Respiratory acidosis
Respiratory alkalosis
High PCO2
Low serum HCO3
High Serum HCO3
Low PCO2

Answer 5

Metabolic acidosis - low HCO3
Metabolic aklalosis - high HCO3
Respiratory acidosis- high pCO2
Respiratory alkalosis- low pCO2

Question 6

Respiratory alkalosis/acidosis is either chronic or acute, metabolic alkalosis is saline responsive or nonresponsive. What are the 2 types of metabolic acidosis?

Answer 6

High anion gap metabolic acidosis (HAGMA)

Normal anion gap metabolic acidosis (NAGMA such as hyperchloermic acidosis)

Question 7

Compensation formula for metabolic acidosis is winters formular which is PCO2 = ?

Answer 7

1.5[HCO3] + 8 +/- 2

Question 8

COmpensation for metabolic alkalosis is that PCO2 will increase by 0.7 for each 1 increase in?

Answer 8

HCO3 from normal (24)

Question 9

Compensation for respiratory acidosis in ACUTE is HCO3 will increase by 1 for every 10 increase in pCO2 (40nl), chronic is HCO3 increases by 3.5 for every?

Answer 9

10 increase in PCO2 (40 nl)

Question 10

Compensation for respiratory alkalosis in ACUTE is HCO decreases by 2 for every 10 dec in PCO2 and chronic is HCO3 decreases by 5 for every?

Answer 10

10mmHg decrease in PCO2 from normal (40)

Question 11

What is the total amount of acid - base disturbances that can be present at once?

Answer 11

3

Question 12

Anion gap is equal to Na+ - (HCO3 + Cl)

The normal range anion gap is?

Answer 12

12+/-2

Question 13

Anion gap is used to differentiate etiologies of metabolic acidosis such as?

Answer 13

High anion gap MA or

Normal anion gap MA (acidosis)

Question 14

HCl being added to the blood in metabolic acidosis offsets the the loss of HCO3, which is why there is a normal anion gap. What are the 2 most common causes of NAGMA?

Answer 14

Renal tubular acidosis and Diarrhea

Question 15

What can falsely lower anion gap and thus must be corrected?

Answer 15

hypoalbuminemia
(for every 1g/dl drop in albumin, AG drops by 2.5)
so if serum albumin is 1.5, normal 3.5…. 2*2.5 = 5 add to anion gap = new anion corrected gap

Question 16

Serum osmolality is normally 275-290 and is calculated using the equation 2(Na) + (glucose/18) +?

Answer 16

BUN/2.8

Question 17

Osmolar gap is serum osmolality minus calculated serum osmolality, normal gap is less than 10, if greater than 10 it suggest WHAT?

Answer 17

Alcohol ingestions - HAGMA *** use osmolar gap for screening for alcohol ingestions, ketoacidosis and lactic acidosis

Question 18

What gap calculation is used in patients with HAGMA to determine if there is coexistent NAGMA or metabolic alkalosis present?

Answer 18

Delta - Delta Gap

Question 19

For every increase in AG, there should be a equal decrease in HCO3. Delta gap is calculated AG - normal AG (12), and delta HCO3 is normal HCO3 minus?

Answer 19

the calculated delta gap = a number

Question 20

if the calculated delta HCO3 is close to the actual HCO3, then no additional acid base disorders. If measured is greater than actual, metabolic alkalosis in addition to HAGMA, if measure is lesser than actual then?

Answer 20

NON-gap metabolic acidosis is present in addition to HAGMA

Question 21

When calculating compensation, if it is an appropriate compensation then it is a simple acid base disorder, if the compensation is inappropriate then there is a ?

Answer 21

mixed acid - base disorder

Question 22

NORMAL VALUES
pH: 7.35-7.44
HCO3: 24
PCO2: 40
Anion Gap: 12
Osmolaltity gap: 10

Answer 22

Meow

Question 23

GOLDMARK is used for HAGMA DDX, the mneumonic includes….
Glycols (ethylene/propylene)
Oxoproline (pyroglutamic/ acetaminophen toxicity)
L-Lactic acidosis
D-Lactic acidosis (short bowel syndromes)
Mehtanol
Aspirin
Renal failure and?

Answer 23

Ketoacidosis (alcoholic/diabetic/starvation)

Question 24

What type of HAGMA acidosis is seen in women who are malnourished or critically ill, with a dx of urinary organic acid screen?

Answer 24

pyroglutamic acidosis (5-oxoproline)

Question 25

``` DDX of increased osmolar gap is remembered via ME DIE: Methanol Ethanol Diethylene glycol (mannitol) Isopropyl alcohol (rubbing alch) and most importantly ****? ```

Answer 25

Ethylene Glycol = ANTIFREEZE

Question 26

Acidosis is associated with hyperkalemia while alkalosis is associated with?

Answer 26

Hypokalemia

Question 27

Normal anion gap metabolic acidosis (NAGMA) is most commonly caused by ureteral diversion or fistula such as ileal conduit post cystectomy, diarrhea and?

Answer 27

renal tubular acidosis

Question 28

What type of RTA occurs when proimal tubule has decreased capacity to reabsorb HCO3, causing low serum HCO3 and high urine HCO3 loss?

Answer 28

Type 2 RTA (see hypokalemia)

Question 29

Urine anion gap is used to differentiate renal from non renal causes of NAGMA and is a clinical marker for what, which indicates appropriate urinary acidification?

Answer 29

NH4CL - ammonium chloride excretion

Question 30

Urine anion gap UAG is calculated by UrineNa+ UrineK - Urine Cl, what does it mean if its negative or positive?

Answer 30

``` Negative = appropriate distal nephron urinary acidification Positive= inappropriate distal nephron urinary acidification ```

Question 31

What type of RTA is distal tubule issue, unable to acidify their urine due to decreased H+ ion secretion? (caused by amphotericin)

Answer 31

Type 1 (d/t sjogrens syndrome/glue sniffing) presents with nephrolithiasis/calcinosis (hypokalemia/low urine pH, UAG positive)

Question 32

What type of RTA is due to a def. in circulating aldosterone or aldosterone resisitance in collecting ducts, causing impaired Na reabsorption by principle cells and leads to hyperkalemia **** (unique, all other RTA cause hypokalemia)?

Answer 32

RTA Type 4 | UAG positive, pH >5.5

Question 33

MCCs of metabolic alkalosis are hypokalemia, vomiting, nasogastric tube suctioning, diuretics, volume depletion and? these are all factors that stimulate Na reabsorption, secondarily increase H secretion and stimulate HCO reabsorption

Answer 33

mineralocorticoid excess

Question 34

Anything that increases respiratory rate or tidal volume can cause?

Answer 34

respiratory alkalosis

Question 35

Anything that lowers respiratory rate/tidal volume, increases dead space, or worsens airway obstruction such as inadequate ventilator settings or increases in CO2 production can cause?

Answer 35

Respiratory acidosis

Question 36

If there are calcium oxalate crystals present in the urine, what is the expected diagnosis? (increased osmolar gap as well)

Answer 36

ETHYLENE GLYCOL

Question 37

If there is a decreased uric acid production in the urine, what can be expected?

Answer 37

PCT issues/dysfunction