Ultrasound has become standard during CPR. A quick look at the heart should, in theory, simplify pulse checks, removing the confusion of whether a perfusing rhythm is present. Differentiating among true cardiac standstill, good contractility, and the nebulous findings in between, however, isn't always so straightforward.
A recent study in Annals of Emergency Medicine assessed physicians' ability to determine when cardiac standstill was present on ultrasound. (2017. doi: 10.1016/j.annemergmed.2017.07.476.) They selected 127 physicians attending six medical conferences as their cohort. It's important to note that this group was varied in their practice, with a mix of EPs, critical care physicians, and even cardiologists, and an assortment of expertise in ultrasound (the majority rated their skill level as less than expert). After a brief presentation on ultrasound in cardiac arrest, the participants were presented with vignette cases. They were asked to evaluate prerecorded clips of echoes and to determine whether cardiac standstill was present.
There was moderate agreement overall, but a few images in particular showed poor agreement within the group: valve flutter with no or poor contractility, movement caused by ventilation, weak contractions, and severe bradycardia with good contractility.
Interesting findings, but do they make a difference in cardiac arrest? Is it important to be able to differentiate between valve flutter with poor contractility and severe bradycardia with good contractility? Recent analysis says yes.
The REASON study is back with a secondary analysis of its landmark data from last year, this time focusing on patients with pulseless electrical activity (PEA). Researchers evaluated all patients with PEA or asystole and their outcomes relative to their ultrasound findings in the original study. (Resuscitation 2016;109:33.) The secondary analysis, also published in Resuscitation, evaluated the outcomes of patients presenting with PEA who had either organized (contractions with changes in ventricular dimensions) or disorganized (agonal twitching) cardiac activity on ultrasound. (2017;120:103.)
They also evaluated outcomes of patients treated with bolus dose, standard ACLS medications, or other methods (such as thrombolytics or continuous adrenergic agents). Their analysis of 225 patients revealed a higher rate of survival to hospital admission in patients with PEA and organized cardiac activity. This effect persisted regardless of the resuscitation approach (ACLS medications versus other methods). Regression analysis revealed that use of methods such as continuous adrenergic agents is associated with increased survival to hospital admission within the organized cardiac activity group.
Ultrasound during CPR pulse checks enables identification of good ventricular contractility and weeds out the pretenders. Although survival to hospital discharge following cardiac arrest remains low, honing in on patients with the best chance of survival may help guide resuscitation efforts and resources.