Thanks the ICU team for presenting a fascinating case of an 86M with multiple myeloma who developed dyspnea and refractory septic shock.
1. Pulse oximetry [measures the %Sat] is usually very reliable in giving us a sense of the amount of oxygen dissolved in the blood. See below for some scenarios in which it may be misleading.
2. Remember that there are many causes of dyspnea that do NOT lead to hypoxemia – e.g., COPD exacerbation, anemia, ACS.
3. In acutely hypoxemic patients, empiric management is often needed – see image below.
Dyspnea versus hypoxemia