Concerning pulses, pressures, myths and facts

[Mike Smertka]

Food for thought,
   
  In 7th edition ATLS ( I know it is not the definitive trauma guide) it is stipulated that a weak peripheral pulse is estimated at 30-40% blood loss, a class III shock state. At that point does it matter if the systolic is ~80? I would think the pulse pressure to be more important. Also there is considerable variation, extremis of age, physical fitness, disease processes, etc. On this very list list, greater minds than I have time and again disuaded the use of systolic BP as a measurement of perfusion. So even if it is accurate does anyone base their therapy on it? Especially considering the use of hypotensive therapy? I could not imagine basing such an intervention on the palpability of a distal pulse. More over, If the patient has a distal pulse but an altered mental status or other sign of hypoperfusion, is the systolic BP of much consequence when not compared to the diastolic? How about in TBI? Does a Strong and bounding pulse measure perfusion to the brain at any
 systolic pressure? 
   
  Now before somebody trumps me with "in the field" nonsense, I ask you to prove to me that the body or medicine functions any differently out of a hospital than in a hospital. When I worked prehospital very rarely did I see a provider take pulses bilaterally (which would present evidence of an isolated perfusion injury.) Very often there was a simultaneous carotid and radial check on one side of the patient. with or without a radial pulse, does it change the common field therapies?
   
  Mike  

trauma at emergencyunit.com wrote:
  http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermTo
Search=10987771&ordinalpos=9&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_Resul
tsPanel.Pubmed_RVDocSum

Deakin rubbishes it. But as Deakin also rubbishes hypotensive resuscitation
on the entirely reasonable grounds that it is unproven: 

http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermTo
Search=16098325&ordinalpos=6&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_Resul
tsPanel.Pubmed_RVDocSum

I doubt anyone here will listen.

BFM

-----Original Message-----
From: trauma-list-bounces at trauma.org [mailto:trauma-list-bounces at trauma.org]
On Behalf Of Carl Robert Christiansen
Sent: 07 October 2007 16:18
To: trauma-list at trauma.org
Subject: Concerning pulses, pressures, myths and facts


Hi all!
Even though I'm a representative of the lists lurkers, I'd like to chance it
on a question this time.

A myriad of emergency medical textbooks state that systolic pressure can be
guesstimated according to pulse location. I.e. a palpable radial pulse
equals systolic pressure above 80-90 mmHg, femoral pulse above 70-80 mmHg
and a carotid pulse above 60 mmHg. I've done several searches (medline,
google scholar, proquest and other local Norwegian sources) and can't find
neither a reliable or an unreliable source of evidence for such a claim. 

I have also been told (from a very unreliable source I might add) that this
claim comes from an old study done on pigs, and that the data was
extrapolated and transferred on to humans. And that a later study has
falsified the pulse-systolic pressure claim. I can't find any references on
this either.

So, is there anyone in here that knows of any strong sources to support
either claim? Is the dogma of radial>90sys, femoral>80sys and carotid>60sys
a myth or a fact?


Your humbly

Carl Christiansen
EMT
University Hospital of Northern Norway




PS.
The only related material I have found is this:

Charles D Deakin and J Lorraine Low. 2000. Accuracy of the advanced trauma
life support guidelines for predicting systolic blood pressure using
carotid, femoral, and radial pulses: observational study. BMJ 2000 321:
673-674. http://www.bmj.com/cgi/content/full/321/7262/673 

DS.




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