4.4 - M&E Acidosis & Alkalosis

Question 1

What is the normal pH of the blood?

Answer 1

7.35-7.45

Question 2

Describe the 3 main pH buffer systems

Answer 2

Blood buffer system - bicarbonate (HCO3-) (increase pH, decrease acidity)

Respiratory - expiration of CO2 (increase pH, decrease acidity)

Kidney excretion / resorption (of HCO3-?)

Question 3

Describe what occurs with respiratory acidosis

Potential Causes

Answer 3

Not breathing out as much CO2 –> increased acidity of blood (decreased pH)

Potential Causes:
- Acute respiratory failure
- COPD
- GBS, myasthenia gravis
- CVA
- Drugs

Question 4

Describe what occurs with respiratory alkalosis

Potential Causes

Answer 4

Hyperventilation –> blowing off too much CO2 –> increased blood pH (more alkaline)

Potential Causes:
- Hypoxemia (PE, high altitude)
- Impaired lung expansion
- Anxiety, stress
- Severe pain
- Mechanical overventilation

Question 5

Describe what occurs with metabolic acidosis

Potential Causes

Answer 5

Lose too much bicarbonate or too much H+ build up in blood

Potential Causes:
- Renal failure (acid retention)
- Diabetic ketoacidosis
- Lactic acidosis

Question 6

Describe what occurs with metabolic alkalosis

Potential Causes

Answer 6

Excess bicarbonate in body fluids

Potential Causes:
- Hypokalemia (diuretics)
- Vomiting
- Excessive HCO3- (TUMS) intake

Question 7

Describe the symptoms of respiratory acidosis

Answer 7

Decreased ventilation

Confusion
Sleepiness
Diaphoresis
Cyanosis

Question 8

Describe the symptoms of metabolic acidosis

Answer 8

Compensatory hyperventilation
N/v
Diarrhea
Headache
Arrhythmias

Question 8

Describe the symptoms of respiratory alkalosis

Answer 8

Hyperventilation
(Kussmaul respirations)

Lightheadedness
Dizziness
Syncope

“Blowing on a campfire”

Question 9

Describe the symptoms of metabolic alkalosis

Answer 9

Compensatory hypoventilation
MM weakness
N/v
Diarrhea
Restlessness

Question 10

Describe how to identify the cause of acidosis or alkalosis

Answer 10

1) Determine pH level — basic or acidic?
2) Determine PaCO2 — =,>, or < 45mmHg?
3) Determine HCO3- — 22-26 (normal), <22, or >26

If PaCO2 or HCO3- is in the same category (basic or acidic) as the Alkalosis vs Acidosis, this determines Respiratory vs Metabolic

If 3rd value is opposite = compensated
If 3rd value is normal = uncompensated

Question 11

Determine what is going on in the following situation:

pH = 7.3
PaCO2 = 50 mmHg
HCO3- = 22-26 mEq/L

Answer 11

Respiratory acidosis