Teaching Medicine - Tutorial: Blood Gases

Blood Gases

Level 1

Tutorial: Blood Gases

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Tutorial: Blood Gases

Learn an organized approach to arterial blood gas analysis, incorporating serum and urine electrolyte values into your more advanced levels of analysis.

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Tutorial: Blood Gases Abnormal Compensation

Lessons

Times Practiced

1284

Cases Completed

1h 24m

Total Time spent

1m 24s

Average Time

Progress

Accuracy

Efficiency

Accuracy

Efficiency

	1	Acidosis or Alkalosis Acidosis or Alkalosis
	2	Shifting chemistry Shifting chemistry
	3	Metabolic or Respiratory Metabolic or Respiratory
	4	Compensatory Processes Compensatory Processes
	5	Degree of Compensation Degree of Compensation
	6	Abnormal Compensation Abnormal Compensation
	7	Anion Gap Mechanism Anion Gap Mechanism
	8	The Delta Delta and Acid Base Ddx The Delta Delta and Acid Base Ddx
	9	Summary of Approach to ABGs Summary of Approach to ABGs

Abnormal Compensation

Please see lesson #4 for "Compensatory Processes" for the podcast on this lesson.

Ok. So you have now calculated the compensation ratio for your patient.

Now what? What if the value is greater than expected? What if it is lower than expected?

Lower than expected #1

remember that it can take time to compensate. Therefore, if the amount of compensation is less than expected, this might represent an acute process that has not had time yet to compensate.
this is especially true for a primary respiratory problem because metabolic compensation can take a few days for the kidneys to adjust the HCO₃^- levels.

Lower than expected #2

sometimes, a second process is happening or maybe the patient can't compensate
as an example, someone with very poor kidney function might not be able to fully compensate for a primary respiratory problem
as a second example, someone with a metabolic acidosis might not appropriately hyperventilate if they received drugs that depress the respiratory center

Higher than expected

the only reason to have more compensation than expected is the presence of a second primary process, also called a mixed acid base disturbance

In summary, these are the 3 reasons why it is important to identify the compensation ratio and determine if it is appropriate or not. Sometimes the primary acid base disturbance grabs all of our attention and we might miss the presence of a second (or sometimes even third). When you are learning about acid base disorders, mixed acid base disturbances can be confusing, so I am trying to highlight them frequently to help you plant some seeds about how to identify them.