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Femoral Artery Ultrasound in Cardiac Arrest

Jul 23, 2024

The Study
Cohen AL et al. Femoral artery Doppler ultrasound is more accurate than manual palpation for pulse detection in cardiac arrest. Resuscitation 2022;173: 157-165.

When we are in the ACLS resuscitation algorithm, following each cycle of compression, we need to perform a rhythm/pulse check. However this can be a challenge for many reasons including: body habits, room temperature, experience and situational stress.

Doppler ultrasound can not only detect a pulse, but can also read peak systolic velocity (PSV), which correlates with systolic blood pressure (in non-cardiac arrest patients).

This study had two objectives:

To assess the accuracy of femoral artery pulsed-wave Doppler ultrasound in comparison to manual palpation to detect any pulse with an arterial line waveform for patients in cardiac arrest.
To determine whether peak systolic velocity (PSV) on Doppler ultrasound accurately detects a pulse with an adequate blood pressure needed for perfusion, which we defined as...

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The Study
Cohen AL et al. Femoral artery Doppler ultrasound is more accurate than manual palpation for pulse detection in cardiac arrest. Resuscitation 2022;173: 157-165.

Doppler ultrasound can not only detect a pulse, but can also read peak systolic velocity (PSV), which correlates with systolic blood pressure (in non-cardiac arrest patients).

This study had two objectives:

To assess the accuracy of femoral artery pulsed-wave Doppler ultrasound in comparison to manual palpation to detect any pulse with an arterial line waveform for patients in cardiac arrest.
To determine whether peak systolic velocity (PSV) on Doppler ultrasound accurately detects a pulse with an adequate blood pressure needed for perfusion, which we defined as a SBP > 60 mmHg.

What They Did

This was a prospective, cross-sectional, partially blinded, diagnostic accuracy study, performed in one emergency department.

Patients included:

> 18 years old.
Non-traumatic cardiac arrest.
Had a femoral arterial line in place

Emergency Physicians were trained in femoral artery pulsed-wave doppler ultrasound performance

Manual palpation was at the femoral or carotid arteries.

Ultrasound was performed and when the femoral artery was identified, the pulsed wave doppler function was enabled.

Primary Outcome

To determine the accuracy of Doppler ultrasound compared with manual palpation for detecting any pulse with an arterial line waveform.

Pulse detection by manual palpation was either present or absent
Pulse detection by Doppler ultrasound was present if waveform was visualized and absent if not visualized.

Secondary Outcome

To determine if the PSV on Doppler ultrasound could detect a pulse with a SBP > 60 mmHg.

N= 54

What they Found

Primary Outcome

Doppler ultrasound had higher accuracy than manual palpation for detection of any pulse (95.3% vs. 54.0%; p < 0.001).
When analysing for the presence of a pulse with SBP > 60 mmHg the accuracy of Doppler ultrasound was lower, although more accurate than manual palpation (77.6% vs. 66.2%; p = 0.011).
In detecting a pulse with SBP > 60 mmHg, the sensitivity of manual palpation was low at 47.4%; however, the specificity of manual palpation was higher than Doppler ultrasound (82.3% vs. 58.4%; p < 0.001).

Secondary Outcome

There was a strong correlation between PSV and SBP with a cut-off value for PSV associated with a SBP > 60 mmHG was 20 cm/s and the accuracy of a SBP > 60 on Doppler ultra- sound was higher than manual palpation (91.4% vs. 66.2%; p < 0.001).

Conclusions

By The Authors

In this study of ED cardiac arrest patients, femoral artery Doppler ultrasound was more accurate than manual palpation for detecting any pulse, and when using a PSV > 20 cm/s, it was also more accurate for detecting a pulse with a SBP > 60 mmHg.

My Take on This

This is a single centre study, with a small sample size and little information on methodology. There may be selection bias here as this was a convenience centre.

This study will not change my current study, but reinforces it. At present, I like to look at the heart during cardiac arrest. I use a subcostal 4 chamber view. If I can get a good view, not only do I have information on the heart and its contractility, but I can also guide compressions. If I cannot get a good cardiac view, I go to a femoral artery view. I keep the probe on, whilst cardiac compressions are being performed. This makes it easier to see the continuation, or discontinuation of the arterial impulse.

What is important in this study is the finding of PSV and the potential for using this as a surrogate marker for blood pressure.