ATLS - Palpable Pulses are Inaccurate
ATLS: Palpable pulses are inaccurate
Take Home Points
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
There were two studies [Poulton, 1988; Deakin, 2000] that evaluated this paradigm. 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.
"ATLS Paradigm Fails" [Poulton, 1988]
What they did: Manually measured SBP with sphygmomanometer in 20 hypovolemic trauma patients and compared with ATLS
- 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" [Deakin, 2000]
What they did: Measured SBP with arterial line in 20 patient with hypovolemic shock and compared to pulses 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 mmHg
- Group 2: Femoral and carotid pulses only
- 10/12 (83%) had SBP <70 mmHg
- 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 mmHg
Conclusion: ATLS guidelines for assessing SBP are inaccurate and generally overestimate the patient’s SBP.
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