In Advanced Trauma Life Support (ATLS), we learn that a carotid, femoral, and radial pulse correlates to a certain systolic blood pressure (SBP) in hypotensive trauma patients. Specifically ATLS states:
Is this true or a myth?
There are two studies that evaluated this paradigm.
Poulton TJ. ATLS Paradigm Fails. Ann Emerg Med 1988; 17: 107. PMID: 3337405
What they did: In 20 hypovolemic trauma patients with SBP <90 mmHg, the investigators palpated pulses and correlated to BP with sphygmomanometry (BP cuff).
Deakin CD, Low JL. Accuracy of the advanced trauma life support guidelines for predicting systolic blood pressure using carotid, femoral, and radial pulses: observational study. BMJ. 2000 Sep 16;321(7262):673-4. PMID: 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:
Conclusion: ATLS guidelines for assessing SBP are inaccurate and generally overestimate the patient’s SBP.
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.