On this episode of ECREM|talks, we are joined by Dr Laila Hussein- an EM Specialist at Sheikh Shakhbout Medical City, Abu Dhabi, and creator of www.UltrasoundEM.com as we explore some emerging concepts in the field of cardiac arrest resuscitation. In particular, we dive into the reliability of manual pulse checks in the arrest patient and the potential application of Point of Care Ultrasound (PoCUS) to improve accuracy. Also, we break down the utilization of cardiac ultrasound in arrest, differentiating fine VF and cardiac standstill and understanding the concept of a ‘pseudo-PEA’.
Hosts: Mohammad Anzal Rehman
Recorded at Khalifa University, Abu Dhabi
Written Summary
CARDIAC ARREST – CAN WE DO BETTER? – PoCUS Pulse Checks & Pseudo-PEAs
“At a cardiac arrest, the first procedure is to take your own pulse”
- Samuel Shem
The concept and management of sudden death from stopping of the heart, also known as cardiac arrest, has evolved significantly over the centuries. Most attempts at resuscitation were largely experimental and the majority were often considered as almost futile measures. The 18th century saw the first use of mouth-to-mouth breaths in victims of drowning. This was later incorporated into management of ‘sudden death’.
Subsequently, chest compressions and use of electricity to reinstate heart beats began to emerge as treatment modalities and, in the 20th century, the formation of the American Heart Association (AHA) led to improved standards in practice during resuscitation, culminating in the establishment of Advanced Cardiac Life Support (ACLS) courses and institutions such as the International Committee on Resuscitation (ILCOR)
Despite considerable advancements in resuscitative care in this time, approximately 9 out of 10 patients with cardiac arrest still do not survive to hospital discharge, showcasing the need for further developments in care to improve our practice for cardiac arrest. Below are a few novel ideas and potential strategies within the Emergency Department that may lead to further development and, hopefully, improved outcomes in resuscitation.
PoCUS Pulse Checks
Pulse checks are a mainstay in most Basic Life Support (BLS) courses. Any individual that collapses and is unresponsive should be evaluated for presence of pulse, usually at the region of the carotid artery using two fingers, colloquially referred to as our ‘digitometer’.
In a study by Eberle in 1996, 200 first responders were asked to check pulses on patients undergoing coronary artery bypass grafting. [1] 10% missed an absent pulse, while 45% missed the presence of a pulse (despite a Systolic BP >80mmHg). Overall, only 15% of participants were able to arrive at an accurate diagnosis for pulse in less than 10 seconds. Ignoring the glaring flaws in accuracy, this brought to attention the fact that healthcare providers take way too long to verify pulses in patients, further evidenced in another study with EM and ICU Physicians and nurses where only 43% of participants detected pulse in less than 5 seconds. [2] In 2000, a subsequent study featured a diagnostic accuracy of approximately 40% within 10 seconds among BLS providers. [3]
This puts the accuracy of our digitometers at about 50-50, with a serious need for speed to accomplish our verification within 10 seconds. Can we do better?
You’d be hard-pressed to find an EM Physician who isn’t a fan of Point of Care Ultrasonography (PoCUS) in the ED. Indeed, there are many ways this nifty device may be used to augment our care within the Emergency Department. To nobody’s surprise, it’s actually quite handy for pulse checks too.
In 2018, the use of doppler US was compared against manual pulse checks and found that use of PoCUS did not take longer than digitometers. However, ultrasound was associated with more accurate diagnoses when compared to use of fingers to assess pulse. [4] This was evidenced again in a Randomized Controlled Trial of 111 patients where doppler ultrasound was not slower than manual pulse checks but did have substantially greater first pass success rates (99% vs 85%). [5]
99% sounds quite optimistic, but when you consider the technique of PoCUS pulse check, it’s easy to see why it wouldn’t be hard to miss detection of pulses. A linear (vascular) or high-frequency probe is often used and placed at the region of interest, much like during a central line insertion, in the horizontal plane to assess the vessels therein. Visualization of a pulsating, thick-walled vessel (hypoechoic lumen) equates to a positive pulse, the absence of which is a negative one- this can be confirmed by compressing the vessels. If both artery and vein compress with force, there is inadequate flow through the artery, constituting a negative pulse.
Bedside Echos & Pseudo-PEAs
Most resuscitation algorithms, such as the ACLS, will separate management of cardiac arrest patients based on the observable rhythm on the attached cardiac monitor. The core difference stems from the rhythm being shockable (pulseless Ventricular Tachycardia or Ventricular Fibrillation (VF)) or non-shockable (Asystole or Pulseless Electrical Activity (PEA)). Identification of the type of rhythm is usually straightforward, but often times you are met with rhythm like fine VF that oscillates with such little amplitudes, it may even mimic an asystole rhythm.
With the administration of shock being so crucial in cases of VF, it then becomes vital to confirm the rhythm before proceeding with the wrong protocol. In these instances, a bedside ultrasound of the heart provides valuable, real-time answers on what exactly is going on inside the body. Direct visualization of the cardiac chambers enables the operator to instantly differentiate a fine VF from an immobile heart, helping make the decision on which algorithm to follow less confounding.
Pulseless Electrical Activity (PEA) is where things get a little more interesting. Normally, a PEA is described when organized electrical activity on the cardiac monitor happens in conjunction with an absent palpable pulse. However, a new term, known as pseudo-PEA has been making the rounds in the FOAMed world for a while now and is worth taking note of.
Simply put, pseudo-PEA is the term used to describe organized activity on the cardiac monitor with absent palpable pulse but an observed presence of CARDIAC activity/contractility on the bedside echo. This can somewhat be interpreted as a state of profound shock where cardiac motion is present, just not sufficient to culminate in a significantly perfusing rhythm (manifested as an absent palpable pulse). In the same vein, a true PEA would be where an organized activity, with absent palpable pulse, has an observed absence of cardiac motion on echo, also known as cardiac standstill. Alternative terminologies, helmed by Dr Scott Weingart of EMCrit, describe these phenomena as Pulseless with a Rhythm with Echocardiographic Motion (PREM) and Pulseless with a Rhythm with Echocardiographic Standstill (PRES)
True PEA = PRES = Absent palpable pulse + Organized electrical activity + No cardiac motion on US
Pseudo PEA = PREM = Absent palpable pulse + Organized electrical activity + Cardiac motion on US
Why does it matter which is present? Because pseudo-PEA carries a vastly greater prognosis when present in patients as compared to true PEA (where survival has been seen to consistently be very low). Since pseudo-PEA is akin to a low flow state, it tends to respond better to resuscitative measures that incorporate vasopressors. Therefore, identifying pseudo-PEA vs true PEA allows the ED Physician more information on where the resuscitation is heading and whether it is likely to respond to further measures. [6]
PEA management as a whole can be streamlined using PoCUS as well. Rather than mentally run through the H’s and T’s (sometimes a lot of components can be missed in the chaos of a resuscitation room), bedside ultrasound can be used to identify the most pressing mechanical causes of arrest, such tamponade, PE or hemo/pneumothorax. Enter the Cardiac Arrest Sonographic Assessment (CASA) protocol, established in a study from 2017,[7] which focused on a stepwise sequential examination of the heart during cardiac arrest care, to look for:
1. Tamponade- signs of pericardial effusion with RV collapse. If present, pericardiocentesis can be performed as needed
2. Signs of Pulmonary Embolism- visualized RV strain. Though this isn’t very specific for PE (RV strain can occur even as a consequence of prolonged CPR), it helps solidify suspicion of PE, if seen in conjunction with other risk factors and when history seems to suggest this as the cause
3. Cardiac activity- the last step in the CASA protocol is kept at the end for a good reason. By this time, evaluation of motion vs standstill may help elucidate probable prognosis. Moreover, it may help identify the true cardiac rhythm when correlated with the cardiac monitor (as in the case of fine VF and pseudo-PEAs described above)
Some ancillary steps may also be performed to look for pneumo- and hemothorax and perhaps extend with a conventional FAST scan and assessment of the aorta for AAA. Although mechanical causes of arrest are associated with poor survival, early detection and intervention still can play an extremely crucial role in improving outcomes.
Conclusion
While cardiac arrest care has grown significantly over the years, perhaps there is room to grow, especially with the advent of PoCUS in the ED. Manual pulse check reliability is much lower than is workable for resuscitation, and efforts to incorporate PoCUS pulse checks may improve our assessment of unresponsive patients.
Evaluation of presence and type of cardiac motion gives us real, actionable information, preventing any second guessing when looking at an ambiguous electrical rhythm. Appropriate use of PoCUS during compression pauses also allows us to identify and act on reversible mechanical causes of arrest without delay and this may be a good way to establish earlier interventions with hopefully improved outcomes in the future.
About Our Guest:
Dr Laila Hussein is an EM Specialist at the Sheikh Shakhbout Medical City in Abu Dhabi. Laila is an MBBS graduate from University of Jordan who completed her residency training in Emergency Medicine at Rashid Hospital, Dubai, UAE. She holds an Arab board and European board in Emergency Medicine. Laila has a special interest in Emergency Medicine ultrasound and has obtained a Master’s degree in Point of Care Ultrasound at Teesside University, United Kingdom. She is one of the pioneers in point of care ultrasound education in Dubai and a director of Point of Care Emergency Ultrasound course held on regular basis in Dubai and Northern Emirates. Laila is also the creator and editor of www.UltrasoundEM.com.
Author: Mohammad Anzal Rehman
A final year Emergency Medicine Resident at Zayed Military Hospital in Abu Dhabi, UAE, maintaining a vested interest in sharing updated knowledge and developing teaching tools, continually striving to incorporate the newest clinical research into practice. Founder/President of the Emirates Collaboration of Residents in Emergency Medicine (ECREM) as well as Editor-in-Chief for the Emirates Society of Emergency Medicine (ESEM) Monthly Newsletter.
REFERENCES
1. Eberle, B., Dick, W. F., Schneider, T., Wisser, G., Doetsch, S., & Tzanova, I. (1996). Checking the carotid pulse check: diagnostic accuracy of first responders in patients with and without a pulse. Resuscitation, 33(2), 107–116. https://doi.org/10.1016/s0300-9572(96)01016-7
2. Ochoa, F. J., Ramalle-Gómara, E., Carpintero, J. M., García, A., & Saralegui, I. (1998). Competence of health professionals to check the carotid pulse. Resuscitation, 37(3), 173–175. https://doi.org/10.1016/s0300-9572(98)00055-0
3. Moule P. (2000). Checking the carotid pulse: diagnostic accuracy in students of the healthcare professions. Resuscitation, 44(3), 195–201. https://doi.org/10.1016/s0300-9572(00)00139-8
4. Zengin, S., Gümüşboğa, H., Sabak, M., Eren, Ş. H., Altunbas, G., & Al, B. (2018). Comparison of manual pulse palpation, cardiac ultrasonography and Doppler ultrasonography to check the pulse in cardiopulmonary arrest patients. Resuscitation, 133, 59–64. https://doi.org/10.1016/j.resuscitation.2018.09.018
5. Badra, K., Coutin, A., Simard, R., Pinto, R., Lee, J. S., & Chenkin, J. (2019). The POCUS pulse check: A randomized controlled crossover study comparing pulse detection by palpation versus by point-of-care ultrasound. Resuscitation, 139, 17–23.
6. Rabjohns, J., Quan, T., Boniface, K., & Pourmand, A. (2020). Pseudo-pulseless electrical activity in the emergency department, an evidence based approach. The American journal of emergency medicine, 38(2), 371–375. https://doi.org/10.1016/j.ajem.2019.158503
7. Gardner, K. F., Clattenburg, E. J., Wroe, P., Singh, A., Mantuani, D., & Nagdev, A. (2018). The Cardiac Arrest Sonographic Assessment (CASA) exam - A standardized approach to the use of ultrasound in PEA. The American journal of emergency medicine, 36(4), 729–731. https://doi.org/10.1016/j.ajem.2017.08.052