Today we heard a very complicated case of a patient with known hematologic malignancy and a previous bone marrow transplant who presented with acute dyspnea, fever, and hypoxemia. The clinical exam was suspicious for congestive heart failure, in particular with RV overload/dysfunction.
We cast an appropriately wide net, thinking about a differential diagnosis that was most consistent with one/multiple of:
In medicine we often attempt to find one unifying diagnosis that explains all symptoms -- in satisfying what is known as
Occam's Razor.
The important teaching point in a complicated case like this is that the patient may have multiple diagnoses and that we must keep an open mind. In response to Occam's Razor,
Hickam's Dictum states that "[the patient] can have as many diseases as the damn well please".
Another important point is that while inelligant, in significantly ill patients who are awaiting a diagnosis empiric therapy for multiple conditions may be considered. In this case emperic broad-spectrum antibiotics (for example ceftriaxone + quinolone), treatment of CHF (lasix, nitrates as tolerated, ideally IV) , and empiric treatment for PE (based on our clinical suspicion, the high likelihood that a secondary event would be fatal, and the delay in being able to get a diagnostic test) were all appropriate. In this case, with unclear renal function, IV heparin is probably safer.
I alluded to the fact that the date of the allogeneic bone marrow transplant may be relevant to the differential diagnosis. The following figure from uptodate illustrates this point.
Early infections (pre-engraftment of the donor marrow) tend to occur with usual bacterial pathogens (gram positive and negative including pseudomonas), invasive candidiasis and aspergillosis, and herpes simplex and respiratory viruses.
Once the donor marrow has engrafted, the risk of non-encapsulated bacterial infections and decreases. However, the risk of encapsulated organisms and aspergillosis persists and the risk of more unusual opportunistic infections increases. These include CMV and other herpes viruses, toxoplasmosis, and PCP.
Later on, while the risk of VZV and EBV increases as well.
