Blood Gases and Respiratory Failure

What this deck covers

Blood Gases and Respiratory Failure in twelve clinical teaching cases with worked explanations. Each case gives you a clinical vignette, four options, the correct answer, and an explanation of why each of the other three is wrong.

The 12 cases, in order

1. Read it in the same order every time
2. Which kind of failure is this
3. How long has it been high
4. Something has been added
5. How far should it move
6. The most dangerous normal number
7. Which sample answers the question
8. Why ninety per cent matters
9. The next step up
10. When the mask is wrong
11. Living with a high carbon dioxide
12. Putting one gas together

Diagnoses and management options tested

Across the twelve cases you are asked to choose between options such as: A primary metabolic acidosis, An acute respiratory acidosis needing immediate intubation, A primary metabolic alkalosis, A chronic respiratory acidosis, largely compensated, A respiratory acidosis with metabolic compensation, A primary respiratory alkalosis, Evidence of respiratory failure, A sampling error, A venous sample, which measures oxygenation accurately, Escalate to non-invasive ventilation, Intubate and ventilate.

Clinical pearls from this deck

• Same order, every gas. The number that decides management is usually the one you reach last.
• The carbon dioxide separates them. Low oxygen with a low carbon dioxide is type 1; low oxygen with a high carbon dioxide is type 2.
• The bicarbonate dates the problem. A high bicarbonate means the carbon dioxide has been high for days, not hours.
• Sodium minus chloride minus bicarbonate. A raised gap means an acid was added; a normal gap means bicarbonate was lost.
• Compensation moves the pH towards normal and stops there. It never overshoots, and it never fully corrects.
• A normal carbon dioxide in an asthmatic child working hard is not reassurance. It is the moment the pump starts losing.

The deck above is free and needs no sign-in. Work through it once for recognition, then again a week later to test yourself — each question has one best answer and a worked explanation.