Is ATLS wrong about palpable blood pressure estimates?

01 Nov
November 1, 2013
ATLSIn Advanced Trauma Life Support (ATLS), we learned that a carotid, femoral, and radial pulse correlates to a certain systolic blood pressure (SBP) in hypotensive trauma patients.  Specifically ATLS stated:
  •  Carotid pulse only = SBP 60 – 70 mmHg
  •  Carotid & Femoral pulse only = SBP 70 – 80 mmHg
  •  Radial pulse present = SBP >80 mmHg

Is this true or a myth?  

There were two studies that evaluated this paradigm.
“ATLS Paradigm Fails” (3337405)
 What they did: In 20 hypovolemic trauma patients with SBP
  •  5/20 (25%) pts were correctly predicted by ATLS guidelines
  • 10/20 (50%) pts had false overestimation of BP by ATLS guidelines
  •  False overestimation of BP was greatest in pts with lowest BPs
  • Mean difference of actual and estimated BP using ATLS was 34 mmHg

Conclusion:  Radial pulses are often present in severely hypotensive hypovolemic patients, meaning the ATLS paradigm is invalid.

“Accuracy of ATLS guidelines for predicting SBP” (10987771)

What they did: In 20 pts with hypovolemic shock and arterial lines, pulses were palpated by an observer blinded to BP readings.

What they found: The disappearance of pulse always occurred in the following order radial > femoral > carotid pulse. There were 4 subgroups:
  • Group 1: Radial, femoral, and carotid pulses present
    • 10/12 (83%) had SBP< 80 mm Hg
  • Group 2: Femoral and carotid pulses only
    • 10/12 (83%) had SBP < 70 mm Hg
  • Group 3: Carotid pulse only
    • 0/4 (0%) had SBP >60 mmHg
  • Group 4: Radial, femoral, and carotid pulses absent
    • 2/3 (67%) had SBP < 60 mm Hg

Conclusion: ATLS guidelines for assessing SBP are inaccurate and generally overestimate the patient’s SBP.

BOTTOM LINE

Although very small studies, they were done by two different authors, using different methods (BP cuff vs arterial line).  Both came to the same conclusion: ATLS overestimates SBP based on palpation of radial, femoral, & carotid pulses. Another way to state this is, if using ATLS guidelines to guestimate BP, we are grossly underestimating the degree of hypovolemia our patients have.

UPDATE: These recommendations have now been removed from the 8th and 9th edition of ATLS

Bibliography

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Salim Rezaie

Emergency Physician at Greater San Antonio Emergency Physicians (GSEP)
Creator & Founder of R.E.B.E.L. EM
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9 replies
  1. Stephen Smith says:

    I trust neither pulse nor BP measurements when patients are in shock. I’ve seen many patients in arrest by cardiac echo who have “normal” BP by sphygmomanometry. The methods of these two studies rely on sphygomanometry in these patients, and those too are notoriously unreliable. One should be very skeptical of any BP measurement, especially low ones, in patients in shock or suspected of shock. One should be just as skeptical of pulse.

    Reply
  2. Stephen Smith says:

    Sorry, I meant one should be particularly skeptical of normal or high BP. Do not be too skeptical of the low ones.

    Reply
    • Salim Rezaie says:

      Hello Steve,
      TY for reading and leaving your comment. Agree with you 100%. If I feel a pulse all that tells me is they have a pulse. Nothing more and nothing less. If we rely on normal or high BP or pulse alone we are grossly underestimating the severity of our patients shock. This is where I see ultrasound playing a bigger and bigger role. US of the heart, IVC, and lungs gives us so much more reliable information.

      Salim

      Reply
  3. Shaun says:

    Doesn’t this imply that BP is a direct measurement? It isn’t! What are we actually looking for? We take BP to ensure tissue perfusion. Although a radial pulse may nor correlate well to BP measurements, it is a more direct measurement of tissue perfusion. Keep your numbers, I want to know if the blood is getting to the peripheries. I would, therefore, argue that pulse is a direct measurement, and blood pressure is indirect for tissue perfusion. Put it back in the ATLS!

    Reply
    • Salim Rezaie says:

      Hey Shaun,
      Appreciate your thoughts and comments. Firstly, just palpating a pulse does not equal perfusion. As shown by the A-line study, it is not even close. I would argue, that arterial lines are a more accurate measure of perfusion than palpating pulses. Secondly, the number one reason these patients die is hypovolemia not hypoperfusion. Just palpating a pulse does not tell you the degree of hypovolemia your patient has. If you depend on palpating pulses you are grossly underestimating volume and perfusion.

      Salim

      Reply
  4. SebiD says:

    Heyyy there…

    So we learned to use capillary refill time (crt) in primary survey…

    ( of course we need to exclude people with icschemic arms and legs in the following)

    Some people with a low blood pressure do have a great CRT (<2sec).

    But I read somewhere that crt would tell us much more than a BP about perfusion e.g. in a shock or with septic people, they might have a normal BP but the perfusion in the extremities is already down…

    Could you provide some information like this post about the reliable of CRT?

    Reply

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