Relative Bradycardia

Big PimpingRelative Bradycardia

There are several things that Jay-Z and I have in common, but one that might not be obvious is our mutual love for Big Pimping! Now, I realize that “pimping” residents and medical students has gone out of style a bit … certainly the flogging had gotten a bit extreme at times… but we should still inquire what our team members know and if we can do that in a fun way while wearing cool hats there should be no harm in that.

But, let us not forget that Pimping Ain’t Easy.  First of all… no flogging.  Equally important is focusing on esoteric information without distinguishing between it and what is clinically useful.  A great example came up recently: Faget’s Sign.

Faget’s Sign

  • Sign described by Jean C. Faget (French physician: 1818-1884)
  • Relative bradycardia compared to what would be expected with fever.

    Associated Conditions

    • Often spoken of in Pimping sessions as being related to interesting infections like Yellow Fever and Typhoid Fever.
    • Potential Culprits:
      • Salmonella typhi (Typhoid Fever)
      • Legionella
      • Chlamydia
      • Mycoplasma
      • C. Brunetti (Q Fever)
      • Yellow Fever (viral hemorrhagic disease)
      • Dengue Fever
      • Brucella
      • Tularemia
      • Colorado Tick Fever (Coltivirus)
      • Leshmaniasis
      • psittacosis
      • leptospirosis
      • Sure some other unusual infections can do it also…

    Don’t Forget…

    The problem with asking about the significance of Faget’s Sign is that we often focus on the unusual infectious causes (seriously, I have to look up half of these… it has been a long time since I read Microbiology Made Ridiculously Simple), but forget to point out that these associations may be more myth than fact and that non-infectious etiologies need to be considered as well.

    • Recall that we often see HR elevate with fever acutely.
      • How much? There is no agreed about amount… but here are two often mentioned:
        • For every 1 degree of fever the pulse increases by 18 beats/min.
        • For every 1 degree of fever the pulse increases by 10 beats/min.
      • Pick whichever one makes your job easier.
    • In chronic conditions (indolent infections, inflammatory conditions, malignancies) these changes might not be present… you may have a relative bradycardia.

    So, while you are pimping / teaching about the interesting phenomenon that Faget described, don’t forget to point out that it is not the sine qua non of any condition… and, while it is fun to know the weird microbes that can be blamed, be diligent and look for chronic conditions that cause fever too!

    Tolia J, Smith LG. Fever of Unkown Origin: Historical and Physical Clues to Making the Diagnosis. Infectious Disease Clinics of North America, December 1 2007; 21(4): 917-936.
     
    Davis TME, Makepeace AE, Dallimore EA, Choo KE. Relative Bradycardia is Not a Feature of Enteric Fever in Children. Clinical Infectious Diseases. 1990; 28: 582-586.
     
Sean M. Fox
Sean M. Fox

I enjoy taking care of patients and I finding it endlessly rewarding to help train others to do the same. I trained at the Combined Emergency Medicine and Pediatrics residency program at University of Maryland, where I had the tremendous fortune of learning from world renowned educators and clinicians. Now I have the unbelievable honor of working with an unbelievably gifted group of practitioners at Carolinas Medical Center. I strive every day to inspire my residents as much as they inspire me.

Articles: 583

7 Comments

    • I have not come across any specific numbers on occurrence of the finding and, as such, I would let its absence steer you away from the diagnosis in the right clinical setting. I will see if I can find any data about the specific rates of occurrence. Thank you!

  2. According to Liebermeister’s Rule, each one degree Celcius (C) rise in temperature results in an increase in heart rate by about 10 beats per minute. However, it is based on normal heart rate of that patient that may vary from 60-100 beats per minute. Most of the bacterial infections with Faget’s sign are caused by intracellular bacteria. Other causes are mainly viral.

    Why all patients with the mentioned diseases do not develop Faget’s sign is not clear. Medical students and doctors are well aware of different presentations in individual patients sufferring from the same disease.

    Remember these dictums
    “Rain fall at all places, but it is the landscape which decides where the water is going to collect.” (We have to wait for era of genomic medicine in every patient!)
    “The disease has not read Medicine” (So it does not follow any rules!)

  4. what is the reason for relative bradycardia, like in obstructive jaundice, the bilirubin acts on the SA node and brings down the pulse…what is the mechanism here sir?

    • Unclear and likely various between the different entities. It is a known finding with certain infections… as well as other conditions (like hemoperitoneum).

      Thank you,
      sean

Comments are closed.