Question

Mrs. Breathless is a 42 year old female, just getting off a late shift. She reports to the ER in the early morning with shortness of breath. After several test, the following results are confirmed: ABG (arterial blood gases) lab results are: pH=7.44, PaCO2 = 28, HCO3 = 24. Problems: PaCO2 is low, pH is on the high side of normal therefore compensate respiratory alkalosis, PaO2 is low probably due to mucous displacing air in the alveoli affected by the pneumonia.

please cite work and no copy and paste

Answer 1

Before we understand this case scenario let us first understand the basic rules of arterial blood gas interpretation:

Normal arterial blood gas report:

pH	7.35 -7.45
pCO2	40-45 mmHg
pO2	85 - 100 mmHg
bicarbonate	22 - 26 meq/l

The basic rules of arterial blood gas interpretation are:

1. pH less than 7.35 = acidosis
2. pH more than 7.45 = alkalosis
3. pCO2 and pH move in opposite directions
   1. If the pCO2 increases the pH decreases.
   2. If the pCO2 decreases the pH increases.
4. The bicarbonate level and pH move in the same direction:
   1. If the bicarbonate increaes the pH also increases
   2. If the bicarbonate decreases the pH also decreases
5. Acid-base disorder can be respiratory or metabolic

   • disorder	pH	pCO2	bicarbonate
     Respiratory acidosis	low	high	normal
     Respiratory alkalosis	high	low	normal
     Metabolic acidosis	low	normal	low
     Metabolic alkalosis	High	normal	High

6. Primary acid-base disorder is the result of the underlying pathology. Once an acid-base disorder develops the body tries to compensate for it. The lungs and the kidneys play an important role in this compensation mechanism

7. Primary disorder	Compensation
   Respiratory acidosis	Metabolic alkalosis
   Respiratory alkalosis	Metabolic acidosis
   Metabolic acidosis	Respiratory alkalosis
   Metabolic alkalosis	Respiratory acidosis

   Now let us look at the history of the patient:

• The patient has breathlessness
  • This means that the patient is hyperventilating.
  • Hyperventilation causes exhalation of carbon dioxide
  • This leads to drop in the pCO2 level
  • A drop in the pCO2 level will cause rise in the pH.
  • Therefore, the pH of this patient is 7.44 which is close to alkalosis and pCO2 is 28 mmHg. This acid-base disorder here is respiratory alkalosis.
  • The compensation for this will be metabolic acidosis. However, in this example the bicarbonates are normal.
  • The hyperventilation may be due to bronchospam ( constriction of the airways)
  • This can lead to low pO2
  • An x-ray will help confirm or refute the presence of pneumonia.