B4-038 Interpreting Arterial Blood Gases

Question 1

a change in the ratio of PCO2/HCO3 predicts the change in

Answer 1

pH

Question 2

normal acid base values
pH
PCO2
HCO3

Answer 2

pH: 7.4
PCO2: 40
HCO3: 24

Question 3

decrease in blood pH below normal range

Answer 3

acidemia

Question 4

elevation in the blood pH above normal range

Answer 4

alkalemia

Question 5

process that increases [H+] by increasing PCO2 or by reducing [HCO3-]

Answer 5

acidosis

Question 6

process that reduces [H+] by reducing PCO2 or by increasing [HCO3-]

Answer 6

alkalosis

Question 7

in a simple disorder, both PCO2 and HCO3 should move

Answer 7

in the same direction

Question 8

will compensation return the pH to normal?

Answer 8

no

just trend it the right way

Question 9

primary disturbance of blood [HCO3-] bicarbonate concentration

Answer 9

metabolic

Question 10

2 types of metabolic acidosis

Answer 10

1. anion gap
2. non anion gap (hyperchloremic)

Question 11

changes in ventilation are mediated by chemoreceptors in the […] and […]

Answer 11

carotid
lower brainstem

Question 12

• [HCO3-] retention
• [HCO3-] is produced more than it is excreted

Answer 12

metabolic alkalosis

Question 13

• nasogastric suction, vomiting
• diuretic therapy
• hyperaldosteronism (Addison’s)
• Cushing
• Exogenous steroids
• Licorice injestion
• Alkali injestion

possible causes of…

Answer 13

metabolic alkalosis

Question 14

[HCO3-] depletion

Answer 14

metabolic acidosis

Question 15

[HCO3-] used up as buffer for acid

Answer 15

anion gap acidosis

Question 16

[HCO3-] loss through urine or bowel

Answer 16

non-anion gap acidosis

Question 17

• methanol
• uremia
• DKA
• paraaldehyde
• INH/iron
• lactic adiosis-sepsis
• ethylene glycol
• salicylates/starvation

can cause…

Answer 17

anion gap metabolic acidosis

Question 18

• hyperailmentation
• acetazolamide
• renal tubular acidosis
• diarrhea
• ureteroenteric fistula
• pancreticoduodenal fistula

can cause…

Answer 18

non-anion gap metabolic acidosis

Question 19

equation used for metabolic acidosis when trying to assess if respiratory compensation is adequate

Answer 19

winter’s formula

expected pCO2= (1.5x[HCO3]) +8 +/-2

Question 20

• CO2 retention
• decreased alveolar ventilation

Answer 20

respiratory acidosis

Question 21

• CNS depression, sedatives
• neuromuscular disorders
• thoracic cage limitations
• acute obstruction
• chronic obstruction
• ventilator malfunction

possible causes of…

Answer 21

respiratory acidosis

Question 22

• CO2 depletion
• increased alveolar ventilation

Answer 22

respiratory alkalosis

Question 23

• anxiety
• CNS disorders
• salicylates, analeptics
• fever, sepsis
• pregnancy -FRC decreases
• liver insufficiency
• hyperthyroidism

possible causes of…

Answer 23

respiratory alkalosis

Question 24

pH < 7.35

Answer 24

acidemic

Question 25

pH > 7.45

Answer 25

alkalemic

Question 26

primary respiratory disturbances will change the [...] primarily

Answer 26

PCO2 | small changes in serum HCO3 in compensation

Question 27

a primarily high PCO2 defines

Answer 27

respiratory acidosis

Question 28

a primarily low PCO2 defines

Answer 28

primary respiratory alkalosis

Question 29

primary metabolic disturbances change the [...]

Answer 29

HCO3

Question 30

a primarily low HCO3 defines

Answer 30

primary metabolic acidosis

Question 31

a primarily high HCO3 defines a

Answer 31

primary metabolic alkalosis

Question 32

determining acute vs chronic respiratory acidosis

Answer 32

Expected pH for acute: pH=7.4 – 0.008 (pCO2 – 40) Expected pH for chronic: pH= 7.4 – 0.003 (pCO2 – 40)

Question 33

if there is a metabolic acidosis, use Winter's formula to

Answer 33

assess if respiratory system is compensating adequately

Question 34

the physiologic response to metabolic acidosis is

Answer 34

hyperventilation

Question 35

if the actual measured PCO2 is much greater than the expected PCO2 from Winter's formula...

Answer 35

the respiratory system is not fully compensating | respiratory acidosis is concurrently present

Question 36

if there is metabolic acidosis, check the

Answer 36

anion gap | [Na+] - ([Cl-] + [HCO3])

Question 37

normal anion gap

Answer 37

12

Question 38

if there is increased anion gap metabolic acidosis, are there other [....] present

Answer 38

metabolic issues | determine corrected bicarb

Question 39

electroneutrality principle

Answer 39

for every molecule of unmeasured anion present, one molecule of bicarb is lost

Question 40

if the corrected bicarbonate is < 22 then

Answer 40

there is additional metabolic acidosis present

Question 41

if the corrected bicarbonate is > 26 then

Answer 41

there is an additional metabolic alkalosis present

Question 42

considered present when there is an abnormality in HCO3 or PCO2 or pH

Answer 42

acid-base disorder

Question 43

key organs to maintaining acid/base balance | 3

Answer 43

* kidney * respiratory system * CNS

Question 44

required lab values to assess acid/base disorders

Answer 44

* ABG: pH, pCO2, bicarb * electrolytes: Na, K, Cl, HCO3 * BUN, glucose, creatinine * good history

Question 45

an imbalance between Na, Cl, and total CO2 is measured as

Answer 45

anion gap

Question 46

MUDPILES for high anion gap acidosis

Answer 46

Methanol Uremia DKA Propylene glycol Infection, Iron, Isoniazid Lactic acidosis Ethylene glycol Salicylates

Question 47

HARDUPS for normal anion gap acidosis

Answer 47

Hyperailmentation Acetozolamide RTA Diarrhea Ureteroenteric fistula Pancreaticoduodenal fistula Spironolactone

Question 48

the compensatory response of the pulmonary system for a metabolic alkalosis is limited a PCO2 between

Answer 48

40 and 50