Emergency department physicians have started using point-of-care ultrasounds (POCUS or POC ultrasound) to identify potentially reversible causes of pulseless electrical activity (PEA) in cardiac arrest patients. Increasing use of POC ultrasound has even led to its current recommendation by the American Heart Association (AHA).
In PEA, the monitor will show electrical activity in the heart but the patient will not have a palpable pulse. Also known as electromechanical dissociation, PEA accounts for approximately 20 percent of out-of-hospital deaths.
Research shows PEA accounts for 68 percent of the recorded in-hospital deaths and 10 percent of all in-hospital deaths. PEA is the first documented rhythm in 30 to 38 percent of adult patients with in-hospital cardiac arrest.
While POC ultrasounds have proven themselves invaluable diagnostic tools, a pair of studies published in October 2017 and January 2018 show use of the ultrasounds during resuscitation of out-of-hospital cardiac arrests may prolong pulse checks and delay chest compressions, which can negatively affect survival.
Various POCUS protocols for cardiac arrest exist, such as Focused Echocardiography in Emergency Life support (FEEL), but concerns over prolonged pauses prevent some ED physicians from using POC ultrasound in cardiac arrest. Obtaining adequate echocardiographic views and interpreting their images during a 10-second CPR pause is challenging for even the most experienced ED sonographers, and delays in obtaining and interpreting the images can lead to unintended prolonged CPR pauses.
Despite Concerns, POCUS Plays an Essential Role in the Management of Cardiac Arrests
Recent evidence presented by the REASON trial demonstrates the usefulness of ultrasound in managing cardiac arrest. Research suggests using the Cardiac Arrest Sonographic Assessment (CASA exam) reduces the duration of interruptions CPR during resuscitation of cardiac arrest. CASA has been proposed as a standardized approach to obtaining a good assessment of the heart while minimizing pauses in CPR during the treatment of PEA arrest.
Using this approach, sonographers would perform a stepwise assessment with each pulse check, rather than performing a full evaluation during a single pause in CPR. During the first break, the sonographer would assess for the presence of a pericardial effusion.
In the second pause, ultrasound examines the right ventricle for enlargement, which could indicate a massive pulmonary embolism. The goal of the third pause is to assess cardiac activity. Sonographers can perform an evaluation for pneumothorax and a focused assessment with sonography in trauma (FAST) exam while CPR is in progress without affecting compressions.
The creators of the CASA exam offered tips to minimize delays in CPR. They suggest the subxiphoid view as the sonographer can position the transducer before the pause, and the area is typically accessible during compressions. A designated clinician other than the code leader should perform the ultrasound. Finally, running a verbal clock during each pulse check keeps everyone focused on the amount of time lapsing.
In a study published in Resuscitation, researchers evaluated videotaped resuscitations to assess the length of pulse checks before and after implementation of the CASA protocol. They found the average pulse check prior to implementing the protocol took 19.8 seconds, and 15.8 seconds after implementation.
The team also learned that planning for pulse checks by getting the transducer in place beforehand saved 3.1 seconds. Utilizing physicians with ultrasound fellowship training saved another 3.1 seconds. The researchers concluded their study by saying that “implementation of a structured algorithm for ultrasound use during cardiac arrest significantly reduced the duration of CPR interruptions when ultrasound was performed.”
