When Ultrasound is Not Your Friend
Rob Orman MD and Bill Reed MD
Take Home Points
- The four components of high performance CPR are rate (100-120), depth (2-2.5 inches), full recoil and minimized pauses.
- Ultrasound can be used on the femoral artery to evaluate CPR.
- In our November 2017 episode, we had a conversation about ultrasound in cardiac arrest.
- Huis, In’t Veld, MA et al. Ultrasound use during cardiopulmonary resuscitation is associated with delays in chest compressions. 2017 Oct;119:95-98.PMID: 28754527
- The take-home point was doing ultrasound prolongs pauses in CPR. The duration of pause was 21 seconds with ultrasound compared to 13 seconds without ultrasound. You need to be cognizant of the ultrasound and how long you are pausing during CPR.
- Reed felt the segment missed the point. This is the first study that shows you shouldn’t have the ultrasound anywhere near a cardiac arrest patient. There may be a small segment of the population where there is benefit. Reed believes the device causes harm.
- This study didn’t demonstrate harm but found pauses associated with use. However, there are other studies that show pauses increase mortality.
- How long does it take to regain perfusion after a pause? The pressure drops back to zero within about 3 seconds. It is not 1 to 1 to get back to where you were. Essentially you have lost about 21 seconds for that 3 second pause. It takes roughly 16 seconds or 30 compressions to get back to where you left off. That is a huge deficit. If you extend that pause up to 21 seconds, it has a negative impact on survivability. We need to do this right.
- The four components of high performance CPR are rate (100-120), depth (2-2.5 inches), full recoil and minimized pauses. That is all you have to do. Precharge your defibrillator 10 seconds before your pause. See what you have. No ultrasound, airway or IV. Intraosseous is faster if available.
- When should ultrasound be used in all-cause cardiac arrest? Reed likes to put it on the femoral artery. He can watch compressions. He can evaluate how the compressor is doing and adjust the quality. He can correlate it with end-tidal CO2. You can watch to see how fast it stops when the compressor comes off the chest.
- Does the subxiphoid view help you in asystole? It may help if there is a return to an organized rhythm. What is the heart doing?
- Count down 10 seconds. If you hit 5 seconds, your CPR fraction will be above 95% which is phenomenal. Our goal is 80%. The AHA says 60% but it is unclear how they arrived at that number. It is easy to do, but you need to cognizant of time.
- You shouldn’t be relying on ultrasound with every pulse check. Keep your hands on the chest. If you bump your CPR fraction by 10%, survivability increases (at least for ventricular fibrillation).
- Think about if ultrasound is going to change your management. Do you really need it?
Patrick B. - March 1, 2018 6:40 AM
POCUS is not getting much love on this chapter, and while the discussion provided makes sense, I don't think POCUS got a fair shake. Particularly since there was a 4x increase in survival with pocus for asystole & PEA patients here:
Cheers. Great episode, point taken on minimizing hands off time.
Dharmesh S. - March 27, 2018 10:35 PM
At our shop we use mechanical CPR (LUCAS). During ongoing chest compressions, the POC US person tries to find a cardiac window around the LUCAS suction cup on the chest. Usually some variant of parasternal long view is possible scanning just above the suction cup. The cardiac views during chest compressions are usually indeterminate to assess for motion, but enough to rule out pericardial tamponade. At pulse check, we take a 4 sec clip while another person is palpating the femoral artery. Loud countdown of 10 to 1 is spoken out, and at 0 LUCAS restarts if there is no pulse.
We believe we are doing a better job than without POCUS in PEA arrests:
- usually the POCUS person shouts out "no pump" within 5 sec if no cardiac movement - so our duration of pulse check is actually lesser than without POCUS.
- we have had patients in whom we discovered hugely dilated right ventricle and survived due to thrombolytic given during CPR
- we also have had unexpected cardiac tamponade patients who survived due to POCUS allowing timely diagnosis and decompression
I think Reed's points may apply when manual as opposed to mechanical CPR is being performed.
However I think his views are too extreme, and it is simply not possible to assess for reversible causes of PEA arrest without ultrasound (and blood gas). Even with manual CPR, every PEA patient should get at least 1 assessment with POCUS, since the best quality of chest compressions will not result in relief of cardiac tamponade or lysis of a massive pulmonary embolus.