November 1, 2013

Is Advanced Trauma Life Support (ATLS) Wrong About Palpable Blood Pressure Estimates?

Written by Salim Rezaie
REBEL EM
Medical Category: Trauma

In 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” [1]

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” [2]

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.

CLINICAL 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

References:

Deakin CD et al. Accuracy of the Advanced Trauma Life Support Guidelines for Predicting Systolic Blood Pressure Using Carotid, Femoral, and radial Pulses: Observational Study. BMJ 2000. PMID: 10987771
Poulton TJ et al. ATLS Paradigm Fails. Ann Emerg Med 1988. PMID: 3337405

Cite this article as: Salim Rezaie, "Is Advanced Trauma Life Support (ATLS) Wrong About Palpable Blood Pressure Estimates?", REBEL EM blog, November 1, 2013. Available at: https://rebelem.com/atls-wrong-palpable-blood-pressure-estimates/.