Pulse Check: time to call the code

Considerations for POCUS use in cardiac arrest.

You just arrived for your 6 a.m. shift and EMS calls your emergency department for a pre-arrival report – “13-month-old girl found down and last seen awake at 2 a.m.”  You’ve been in this dance many times and know exactly what to do. You swiftly gather your residents, nurses and technicians to the trauma bay and prepare.

Assign roles? Check.

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Prepare airway and access equipment? Check.

Draw code medications? Check.

Ready the ultrasound machine? Check.

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The patient is a previously healthy toddler found unresponsive, apneic and pulseless. EMS performed chest compressions on scene and administered several rounds of epinephrine. No ROSC yet. The patient is now intubated on scene. They are five minutes out.

EMS is continuing CPR as your patient is rolled in. Their initial report includes five rounds of epinephrine and GCS of 3. You note a cyanotic child with fixed and dilated pupils. Her skin is cold to the touch. She is pulseless and lifeless.

Despite the grim outlook you decide to continue the code. As part of your recent integration of POCUS in resuscitations, you wait anxiously to place the phased-array transducer in the subxiphoid area to catch a glimpse of her heart for any signs of activity.  Finally, “hold for pulse check,” as you instruct for CPR to stop.

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As the parents arrive to the room, you are desperate for any optimistic sign of cardiac activity.  Instead, you see lack of atrial and valvular movement except for weak contraction of the ventricles in the subxiphoid view (Figure 1. See supplemental video clip online at epmonthly.com).

You are inclined to continue, but your clinical suspicion suggests a pseudo-pulseless electrical alternans (PPEA) not consistent with ROSC.  You are left helpless as your team waits to hear that all too familiar adjudication.

Key Teaching Points

1. Resuscitation in pediatric cardiac arrest is truly one of the toughest cases to work through and unfortunately, most outcomes are futile. We demonstrate a case where a cardiac arrest is not consistent with potential cardiac activity on POCUS. This often results in a process where an already challenging disposition is made worse by questionable cardiac activity that may be incorrectly used as a prognostic indicator to continue resuscitation for ROSC.
2. The use of POCUS in this setting is to support resuscitation by helping to diagnose reversible causes of undifferentiated cardiac arrest. POCUS can also be used to inform the team regarding the quality of chest compressions, monitoring responses to interventions in real time and even guide procedures such as pericardiocentesis and decompression of tension pneumothorax.^[1,4,9]
3. POCUS in cardiac arrest is well-documented in adult literature.[^1-3] For best practices cardiac images are obtained in the subxiphoid (SX) view with a low-frequency phased-array transducer to assess for pericardiac effusion and identify cardiac activity (Figure 1). The transducer is placed away from the compression zone, just inferior to the xiphoid tip of the sternum in epigastric area with the indicator pointing to the patient’s right to visualize all four chambers (Figure 2).
4. Ideally, cardiac POCUS during resuscitation should be performed with limited interruption in 10 seconds or less by a POCUS provider for real time image acquisition and interpretation to aid the team leader in medical decision making.[¹] While there are inherent challenges to image acquisition and real time assessment of the SX window, there are a few considerations to augment this critical evaluation.
5. A common technique to mitigate interruption is to record video clips that are reviewed as resuscitation is resumed. ^[4,5] Understand that the specificity of the POCUS finding may vary for the pathologic cause or may be due to another process unrelated to cardiac arrest. Additionally, there is a wide variation in the definition of cardiac activity, ranging from isolated valvular fluttering or myocardial twitching, to organized left ventricular contractions with coordinated aortic valve opening.[⁶] Underlying factors such as mechanical ventilation and profound bradycardia may also create challenges to assessment.^[4,5]
6. It is generally more acceptable to continue resuscitation efforts rather than deciding to discontinue a case that could result in ROSC. However, variable presenting factors can create bias that influence medical decision-making, and POCUS can play a significant role in resuscitation during cardiac arrest. In the case presented, the cardiac activity was likely due to pseudo-pulseless PEA. First described in 1992, this is often distinguished from true PEA by cardiac output without palpable pulse.^[8]
7. The suspected cardiac activity described in this case proved to be futile as prolonged resuscitation did not change outcome. While ROSC sensitivity is supported from 34% to 79% in adult studies, using POCUS as a reliable predictor of outcome during cardiac arrest is not clear in the pediatric literature^.[3,7] Therefore POCUS should be used as an adjunct to further guide medical decision at the bedside during resuscitation.  Nevertheless, previous study showed a higher ROSC rate (>50%) in patients with detectable cardiac activity on ultrasound while poor in those lack detectable cardiac activity.^[9]

Pearls and Pitfalls

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1. POCUS is a great tool during cardiac resuscitations. Clinicians should be mindful not to rely on POCUS in isolation during cardiac arrest, but rather as an adjunct to the overall clinical assessment.^[4]
2. In cardiac arrest, an organized cardiac activity on POCUS may encourage continuation of resuscitation, but an absence can conversely lead to inappropriate termination of resuscitation.
3. It is important to consider that the greater risk of misinterpreting absence of cardiac activity does not appear to be missed because the outcome of the resuscitations is very poor. The greater risk may be the impact it has on patients, providers and systems at risk when there is ROSC to a patient who may not survive.^[5]
4. Avoid a prolonged time of assessment during pulse checks. Develop an approach that minimizes hands-off time. This can include having a team member count down an estimated 10 seconds from the chest compression pause or recording a clip of the image for subsequent review while the resuscitation is ongoing.
5. Integration of POCUS in the hands of an experienced provider can also augment resuscitation in cardiac arrest by evaluating quality of compressions, allowing rapid diagnosis of reversible causes, monitoring response to treatment and providing prognostic information for the possibility of ROSC and survival.^[6]

References

1. Hazinski MF, Nolan JP, Aickin R, et al. Part 1: Executive Summary: 2015 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. Circulation. Oct 20 2015;132(16 Suppl 1):S2-39. doi:10.1161/CIR.0000000000000270
2. Long B, Alerhand S, Maliel K, Koyfman A. Echocardiography in cardiac arrest: An emergency medicine review. Am J Emerg Med. Mar 2018;36(3):488-493. doi:10.1016/j.ajem.2017.12.031
3. Lalande E, Burwash-Brennan T, Burns K, et al. Is point-of-care ultrasound a reliable predictor of outcome during atraumatic, non-shockable cardiac arrest? A systematic review and meta-analysis from the SHoC investigators. Resuscitation. Jun 2019;139:159-166. doi:10.1016/j.resuscitation.2019.03.027
4. Clattenburg EJ, Wroe P, Brown S, et al. Point-of-care ultrasound use in patients with cardiac arrest is associated prolonged cardiopulmonary resuscitation pauses: A prospective cohort study. Resuscitation. Jan 2018;122:65-68. doi:10.1016/j.resuscitation.2017.11.056
5. Huis In ‘t Veld MA, Allison MG, Bostick DS, et al. Ultrasound use during cardiopulmonary resuscitation is associated with delays in chest compressions. Resuscitation. Oct 2017;119:95-98. doi:10.1016/j.resuscitation.2017.07.021
6. Hu K, Gupta N, Teran F, Saul T, Nelson BP, Andrus P. Variability in Interpretation of Cardiac Standstill Among Physician Sonographers. Ann Emerg Med. Feb 2018;71(2):193-198. doi:10.1016/j.annemergmed.2017.07.476
7. Reynolds JC, Issa MS, T CN, et al. Prognostication with point-of-care echocardiography during cardiac arrest: A systematic review. Resuscitation. Jul 2020;152:56-68.
8. Rabjohns J, Quan T, Boniface K, Pourmand A. Pseudo-pulseless electrical activity in the emergency department, an evidence based approach. Am J Emerg Med. 2020 Feb;38(2):371-375. doi: 10.1016/j.ajem.2019.158503. Epub 2019 Oct 14. PMID: 31740090.
9. Ávila-Reyes, D., Acevedo-Cardona, A.O., Gómez-González, J.F. et al.Point-of-care ultrasound in cardiorespiratory arrest (POCUS-CA): narrative review article. Ultrasound J13, 46 (2021). https://doi.org/10.1186/s13089-021-00248-0