Acid Base Disorders

Question 1

Serum CO2

Answer 1

23-30

Less than 23 acidosis
Greater than 30 alkalosis

Indirect measure of HCO3 in the venous blood

Question 2

Arterial pH

Answer 2

7.35-7.45

Value inversely proportional to the # of H+ ions in the blood
7.4 is normal

7.35 acidic low pH high H+
7.45 alkalotic high pH low H+

Question 3

PaCO2

Answer 3

35-45
Partial pressure of arterial CO2 measure of ventilation

High CO2 —> acidosis
Low CO2 —> alkalosis

Fast RR (hyperventilation) —> more CO2 loss CO2 (acid) —> alkalosis (35)
Low RR (hypoventilation) —> less CO2 loss (retention) —> acidosis (45)

Low pH, low RR, high CO2 —> suppresses brain fx —> coma

Question 4

HCO3 (bicarb)

Answer 4

21-28
Secreted by the kidneys
Increase in HCO3 increase in pH
Direct relation to pH

Question 5

PaO2

Answer 5

80-100
Partial pressure of arterial O2

Amount of O2 in the blood

Question 6

O2 sat

Answer 6

92-100%
Percentage of Hbg that is saturated with O2
Cells have enough O2 to function normally

Question 7

Base Excess-Deficit

Answer 7

-2 – +2
Calculated from pH, PCO2 and Hct

Amount of anions available for buffering

-2 (metabolic acidosis)
+2 (metabolic alkalosis or compensation for respiratory acidosis)

Question 8

A-a gradient

Answer 8

Normal is <10mmHg
Measures the difference between the (A) alveolar (lungs) to (a) arterial O2
Increases 1mmHg for each decade lived

Elevated value means that there is an issue with O2 diffusing across the alveolar membrane.

Ex: pulmonary edema, pulmonary fibrosis, and ARDS

Question 9

Complications of acidosis

Answer 9

Decreased cardiac output
Decreased contractility
Catecholamine resistant hypotension (pressors don’t work at a level of acidosis)
Hyperkalemia

Question 10

Anion gap

Answer 10

4-12 mmol/L
High anion gap —> lactic acidosis, ketoacidosis, acute or chronic renal failure

Low anion gap —> GI losses (N/V/D), large volume of saline administration, medications such as NSAIDs, ACE inhibitors and trimethoprim

Question 11

Metabolic Acidosis

Answer 11

Reduction of serum bicarb with a low pH

Caused by increased acid production, loss of bicarb, diminished renal excretion of H+

Hypoxia —>lactic acid
Ketogenesis (fat for energy) —> DKA Ketones

Medications that treat AIDS and aspirin

HCO3 loss due to severe diarrhea or type 2 tubular acidosis

Question 12

Metabolic Alkalosis

Answer 12

Serum pH greater than 7.4 and bicarb of greater than 28

Excessive HCO3 or deficiency in H+ ions

Seen with hypokalemia and hypocalcemia
Hypoventilation and elevated pCO2 (shallow breathing)

Gastric loss N/V/D or diuretic use (pee H+ out)

Question 13

Respiratory Acidosis S/S

Answer 13

Excessive PaCO2 a decrease in pH

Decreased alveolar ventilation shallow breaths
Increased blood calcium, increased potassium, vasodilation CO2 toxicity, tremors, disorientation, restlessness, muscle twitching, and seizures.

Medullary respiratory center depression
Opiates, barbs, anesthesia, PCO2 retention, head injury

Impaired respiratory muscles
GBS, polio, MS, ALS

Airway obstruction
Aspiration, OSA, laryngospasm, asthma

Impaired gas exchange
ARDS, COPD, PNA, pulmonary edema

Question 14

Respiratory Alkalosis S/S

Answer 14

Deficiency in PaCO2 high pH

Increased alveolar ventilation
Hyperventilation/anxiety

High pH can cause: CNS and PNS problems, dizziness, confusion, paresthesias, seizures, and coma.

Commonly caused by: hypoxemia, Pulmonary Embolism, CHF, high altitudes, fever, gram negative sepsis, severe anemia, hepatic failure, salicylate OD, drugs such as catecholamines, nicotine, progesterone, or mechanical ventilation.