NURS 3330: Acid-Base Practice
Spring 2015
STUDENT:
DATE: _____________
Acid-Base Practice
To understand and evaluate Acid-Base Imbalances, you must:
1.
2.
3.
4.
5.
6.
Know the reference range values of pH, partial pressure of carbon dioxide (PCO2), and bicarbonate (HCO3-)
Look at the patient's ABG's (arterial blood gases)
Determine what is abnormal, and whether the abnormal value(s) are too high or too low
Correlate the abnormal values of PCO2 and HCO3- to the abnormality of pH
Name the imbalance (disorder), the cause, and the source (eg. Respiratory or Metabolic) of any compensation
Suggest possible cause(s) of the imbalance
STEPS:
1.
Reference values for ABG's:
 pH Range:
 Carbon Dioxide Partial Pressure:
 Bicarbonate:
2.
3.
7.35 - 7.45
35 - 45 mm Hg
24 - 28 mEq/L
Evaluate the patient's ABG's:
a)
Is the pH within reference range?
 Is it too high or too low?
 Is it acidosis or alkalosis?
b)
Is the CO2 within reference range?
 Is it too high or too low?
 Will it cause acidosis or alkalosis?
 Will it correct acidosis or alkalosis?
c)
Is the HCO3-within reference range?
 Is it too high or too low?
 Will it cause acidosis or alkalosis?
 Will it correct acidosis or alkalosis?
Correlate the abnormal values:
a)
If only one of the two parameters (CO2 or HCO3-) is abnormal, its value should be consistent with the pH (for example, if the CO2 is
high, since that causes a drop in pH, the pH should be low)
b)
If both of the parameter are abnormal, then one is CAUSING the problem, and the other is trying to CORRECT (COMPENSATE FOR)
the problem

EXAMPLES:
 If the CO2 is high, and is causing the pH imbalance, then the pH must be low, since CO2 behaves as an acid
 If HCO3- level is also abnormal, it will typically be high, to compensate for the low pH, since it is a base
4.
Name the imbalance (disorder):




5.
Respiratory Acidosis
Respiratory Alkalosis
Metabolic Acidosis
(with or without renal compensation)
(with or without renal compensation)
(with or without respiratory compensation)
Metabolic Alkalosis
(with or without respiratory compensation)
Suggest a possible cause
1.
EXAMPLE: Possible cause of chronic Respiratory Acidosis is emphysema
Page 1 of 5
NURS 3330: Acid-Base Practice
Spring 2015
STUDENT:
DATE: _____________
PRACTICE PROBLEMS:
1.
ABG's: pH 7.31 PCO2 55 mm Hg HCO3- 28 mEq/L
ANSWER: (Show each of the 5 steps)
1.
Reference values for ABG's:
 pH range 7.35 - 7.45
 Carbon Dioxide Partial Pressure, 35 - 45 mm Hg
 Bicarbonate, 24 - 28 mEq/L
2.
ABG's: pH 7.31 PCO2 55 mm Hg HCO3- 35 mEq/L
ANSWER: (Show each of the 5 steps)
1.
Reference values for ABG's:
 pH range 7.35 - 7.45
 Carbon Dioxide Partial Pressure, 35 - 45 mm Hg
 Bicarbonate, 24 - 28 mEq/L
Page 2 of 5
NURS 3330: Acid-Base Practice
Spring 2015
3.
STUDENT:
DATE: _____________
ABG's: pH 7.31 PCO2 35 mm Hg HCO3- 20 mEq/L
ANSWER: (Show each of the 5 steps)
1.
Reference values for ABG's:
 pH range 7.35 - 7.45
 Carbon Dioxide Partial Pressure, 35 - 45 mm Hg
 Bicarbonate, 24 - 28 mEq/L
4.
ABG's: pH 7.31 PCO2 25 mm Hg HCO3- 20 mEq/L
ANSWER: (Show each of the 5 steps)
1.
Reference values for ABG's:
 pH range 7.35 - 7.45
 Carbon Dioxide Partial Pressure, 35 - 45 mm Hg
 Bicarbonate, 24 - 28 mEq/L
Page 3 of 5
NURS 3330: Acid-Base Practice
Spring 2015
5.
STUDENT:
DATE: _____________
ABG's: pH 7.48 PCO2 25 mm Hg HCO3- 28 mEq/L
ANSWER: (Show each of the 5 steps)
1.
Reference values for ABG's:
 pH range 7.35 - 7.45
 Carbon Dioxide Partial Pressure, 35 - 45 mm Hg
 Bicarbonate, 24 - 28 mEq/L
6.
ABG's: pH 7.48 PCO2 25 mm Hg HCO3- 20 mEq/L
ANSWER: (Show each of the 5 steps)
1.
Reference values for ABG's:
 pH range 7.35 - 7.45
 Carbon Dioxide Partial Pressure, 35 - 45 mm Hg
 Bicarbonate, 24 - 28 mEq/L
Page 4 of 5
NURS 3330: Acid-Base Practice
Spring 2015
7.
STUDENT:
DATE: _____________
ABG's: pH 7.48 PCO2 45 mm Hg HCO3- 33 mEq/L
ANSWER: (Show each of the 5 steps)
1.
Reference values for ABG's:
 pH range 7.35 - 7.45
 Carbon Dioxide Partial Pressure, 35 - 45 mm Hg
 Bicarbonate, 24 - 28 mEq/L
8.
ABG's: pH 7.48 PCO2 55 mm Hg HCO3- 33 mEq/L
ANSWER: (Show each of the 5 steps)
1.
Reference values for ABG's:
 pH range 7.35 - 7.45
 Carbon Dioxide Partial Pressure, 35 - 45 mm Hg
 Bicarbonate, 24 - 28 mEq/L
Page 5 of 5