Pulmonary Acid Base and Gas Exhchange

Question 1

Acidosis

Answer 1

↓force of cardiac contractions
↓ vascular response to catecholamines
↓ response to the effects and actions of certain medications

Question 2

Alkalosis

Answer 2

interferes with tissue oxygenation

normal neurological and muscular functioning

Question 3

Normal reference ranges

Answer 3

pH 7.35-7.45
PaCO2 35-45 mmHg
PaO2 80-102 mmHg
HCO3 22-28 mmol/L
Anion gap 10-16 mmol/L

Question 4

Hydrogen ions are a product of cellular metabolism

Answer 4

CO2 is a by product of cellular metabolism
Most of the CO2 is transported in the blood as HCO3-
Converting CO2 into HCO3- frees a hydrogen ion
The more CO2 there is the more hydrogen ions are produced

Question 5

Carbonic acid-bicarbonate buffer system

Answer 5

H2O + CO2 ↔ H2CO3 ↔ HCO3- + H+

Question 6

Causes of Respiratory Acidosis

Answer 6

pH low (45 mmHg)
(think high CO2, and all those things that cause a high CO2 like head injury, medications, neuromuscular disease, atelectasis, pneumo, etc...shallow breathing)

Question 7

Causes of Respiratory Alkalosis

Answer 7

pH high ( >7.45) with a PaCO2 low (< 35 mm Hg.)
Think what causes over breathing: fear/anxiety, fever, sepsis, meds, CNS lesions

Question 8

Causes of Metabolic Acidosis

Answer 8

bicarbonate level low (< 22) mEq/L with a pH low (< 7.35)… bowls, renal failure, DKA, diarrhea, starvation

Question 9

Causes of Metabolic Alkalosis

Answer 9

bicarbonate level high > 26 mEq/L with a pH high (> 7.45) antacids, excess bicarbonate, vomiting

Question 10

A-a gradient

Answer 10

Normal values change with age (increase)
Usually the normal is < 10 mmHg
To calculate the estimated A-a gradient
(age/4) + 4 example: (40/4 + 4 = 14)

Question 11

Anion Gap

Answer 11

= (Na+ + K+) – [Cl- + HCO3-]