Do rigors indicate serious bacterial infection?

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We often see children with pyrexia and have to decide on whether or not they have a serious underlying bacterial infection.  When the parent describes, or uses the word ‘rigors’ we all get a bit twitchy ourselves.  But is there any evidence to suggest that rigors = serious bacterial infection?

 

Some more background…

A chill is ‘a sensation of cold occurring in most fevers’.

A rigor is ‘a profound chill with pilo-erection associated with teeth chattering and severe shivering’.

There is general consensus that rigors indicate a rapid rise in temperature, but nobody seems to know whether it indicates bacteraemia.

 

What were the search terms?

Using PubMed, a search was run using

rigors OR rigor OR shaking

AND

bacteraemia OR bacteremia OR sepsis OR septicaemia OR septicemia

 

How many studies have been carried out?

Unfortunately there is only one study on this topic – Tal et al (1997)

Lumsden and Potier reviewed this question for Emergency Medicine Journal in 2007 and also found only one result.  There have been no new studies since then.

 

Ok, well I guess one will have to do.  Who did they look at?

This was a prospective study which included:

100 patients who had a pyrexial illness (>38.5 degrees) along with rigors (febrile seizures were excluded)

334 patient who were matched in age, sex, temperature and clinical state but with NO rigors

 

What investigations did these patients have?

All patients had bloods (FBC, ESR, blood cultures); urine analysis and culture; and CXR.  Some had lumbar punctures.

 

What was the outcome measured?

The outcome was presumed or proven bacterial infections.

Proven was from blood, urine or stool culture.

Presumed was from clinical assessment and CXR (the authors acknowledge that some of these may have been viral).

 

What were the results?

There were significantly greater positive blood cultures in patients with rigors (15%) compared to those without rigors (6%).  This was more significant in those over 1 year old (p<0.015).

The most common pathogen was Strep pneumoniae.

In the presumed bacterial group, more patients had rigors.  This was statistically signifianct (p<0.005)

 

How do we know what a rigor is?

Well, the short answer is….we don’t.

This study relied on parental reporting (60%)  or health professional witnessing (40%).

There is nothing that clarifies the difference between a shiver and rigor so it does make selection a bit tricky.

 

Will/should this study change my practice?

It’s difficult to know what to take from this.

The recruitment of group is questionable as we really don’t know how accurate the assessment of having a rigor was (although that’s the same in actual practice).

That the outcomes include ‘presumed bacterial infection’ means that we don’t actually know whether or not there was a true bacterial infection in the ‘presumed bacterial group’.  So the result that more patients in the presumed bacterial group had rigors is self-fulfilling and therefore not helpful to our practice.

Therefore, the useful outcome is that there was a significant different in positive blood cultures between the rigors and non-rigors group.

It is a small study and the definitions are sketchy, but it is something to go on.

 

I’m still confused – what’s the conclusion?

There has only been one study looking into whether rigors indicate an underlying bacterial infection.  This study does show that more patients with rigors have a positive blood culture.

But the study was small, with definitional problems that have a huge impact on its usefulness.

Not one to hang your hat on, but bear it in mind when you see a patient with rigors.

 

References

Isselbacher KJ. Harrison’s principles of internal medicine, 13th ed. McGraw-Hill Inc. 1994, p83.

Lumsden D, Potier, K. Rigors in febrile children may be associated with a higher incidence of serious bacterial infection. Emerg. Med. J. 2007;24(9): 663.

Tal Y, Even L, Kugelman A, Hardo€ D, Srugo I, Ja€e M. The clinical significance of rigors in febrile children. Eur. J. Pediatr.. 1997;156:457-459.

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About 

Tessa Davis is a paediatric emergency registrar from Glasgow and Sydney, but currently living in London. Tessa tries to spend time with her 3 kids in between shifts. @tessardavis | + Tessa Davis | Tessa's DFTB posts

5 Responses to "Do rigors indicate serious bacterial infection?"

  1. Shane George
    Shane George 3 years ago .Reply

    Hard to interpret this study since we now vaccinate against a number of S.pneumo serotypes.

    If we repeated the study now would we get the same results?? My gut feeling is that we would see no difference, but I have no scientific data to back this up!

    • Tessa Davis
      Tessa Davis 3 years ago .Reply

      Good point. Essentially, even though we speak about rigors meaning something significant with regards to the seriousness of infection, there isn’t actually evidence to back this up.

  2. Bob Phillips
    Bob Phillips 3 years ago .Reply

    There are some data from paed oncology too that show increased risk of bacteraemia:
    http://www.ncbi.nlm.nih.gov/pubmed/21394050

    I wonder if calling a ‘rigor’ rather than a shiver is part of the gut-feeling-badness stuff that we also can demonstrate is real but can’t define what it is:
    http://www.ncbi.nlm.nih.gov/pubmed/20132979

    • Tessa Davis
      Tessa Davis 3 years ago .Reply

      Thanks. I can only see the abstract in the article you mention, but it looks like it uses rigors in combination with other criteria rather than as an indicator alone.

      I think you’re right it’s more a word some people use to voice their gut feeling.

      But often people get bogged down in the ‘was he just shivering or was it a RIGOR?’ conversation.

      It’s usually the parents describing it in the history, and actually it’s not really a strong indicator of anything.

  3. Manuel Datiles III, MD
    Manuel Datiles III, MD 5 months ago .Reply

    I personally experienced rigors while being confined for small bowel and urinary obstruction in April 2016. I am an ophthalmologist and researcher (tenured Senior Investigator) at the NIH in Bethesda MD as well as an adjunct associate Professor at the Johns Hopkins University School of Medicine in Baltimore. I was being treated with NPO diet, IV fluids, a naso-gastric tube and a urinary catheter, and was an in-patient at the Shady Grove Adventist Hospital in Rockville, MD.
    In the morning of April 28, 2016, after brushing my teeth (may have dislodged some plaque into my blood stream?) I developed severe chills and shaking accompanied by high fever (41 degrees celsius) and eventually became tired of the severe chills and shaking with heavy breathing after 10 minutes. My daughter and the staff nurse piled blankets and my overcoat on top of me and took my BP which was 180/100, pulse 120, with temp of 41. I asked for oxygen and the head nurse came and started oxygen and said I had rigors! I asked her to call the Hospitalist on call and ask for help. He immediately prescribed acetaminophen IV and a few seconds after getting the IV dose, my rigors symptoms immediately lessened. After 5-6 minutes the rigors were gone and I felt completely well again with no sequelae, except since I happened to be on cardiac monitoring, the cardiologist was freaking out due to atrial fibs, which disappeared after the rigors stopped. Later I underwent a nuclear stress test (chemical) that showed a very small mild demand ischemia in the cardiac apex which disappeared at rest and she also said rule out possible artifact.
    I don’t know where the rigors came from but it also disappeared as quickly as it came!

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