Do Palpable Pulses Correlate to Systolic Blood Pressure in Hypotensive Trauma Patients?
In Advanced Trauma Life Support (ATLS), we learned that a carotid, femoral, and radial pulse correlates to 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 
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 falsely overestimates systolic blood pressure with palpable pulses.
Accuracy of ATLS guidelines for predicting SBP 
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 editions of ATLS
- 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