Prehospital Tradecraft refers to the methods, techniques and technologies employed in the delivery of modern professional-level medical care in the prehospital environment. Our tradecraft calls for quick thinking, often outside-the-box, while considering the presenting circumstances of a medical problem to quickly develop a proper course of care to stabilize a patient – no matter how confusing or stressful the situation. Prehospital medical providers, especially those assigned to technical rescue teams, can encounter cardiac arrest caused by unique situations requiring specialized resuscitation measures and interventions.
One of the core attributes of a solid prehospital provider is the ability to use differential diagnosis to address causes beyond the standard cardiac arrest algorithm early enough in the reanimation process to make a difference. This article is part one of a two-part series and will outline some of the more uncommon clinical presentations and treatment of cardiopulmonary arrest that may be encountered by EMS personnel assigned to technical rescue duty, though this information can be applicable for all first responders.
- Preventing Reperfusion Injury During Cardiac Arrest
- Head-Up CPR May Improve Neurologically Intact Survival Rates
- Mechanical CPR: A Critical Element in Any Cardiac Arrest Bundle of Care
- Active Compression-Decompression CPR Plus an Impedance Threshold Device
The American Heart Association (AHA) recently released its 2020 Emergency Cardiac Care (ECC) Guidelines. Included in the new 2020 ECC guidelines is a robust subsection of recommendations addressing cardiac arrest in special situations. The AHA has republished the majority of the 2010 and 2015 special circumstances of cardiac arrest section in the new ECC guidelines with relatively few changes.1 Though some of the core recommendations covering special situations have essentially remained the same for the last decade, most of them retain their validity under the new 2020 ECC guidelines.2
On the streets, we have only just begun to really acknowledge that good BLS, an AED, and quality CPR is much more relevant to return of spontaneous circulation (ROSC) than advanced life support (ALS) procedures. Contrary to the para-god persona, ALS has not been shown to definitively improve the probability of a successful outcome from cardiac arrest, i.e. discharge from the hospital neurologically intact. However, ALS plays a much bigger part in the chain of survival during the peri-arrest periods, either during pre-arrest attempts at stabilization or post-arrest stabilization immediately following ROSC.
Based on several comprehensive studies involving out-of-hospital (medical) cardiac arrest, the chance of achieving ROSC is dependent on immediate initiation of uninterrupted high-quality chest compressions which has a ROSC range from 7.2 to 11%.3, 4 Furthermore, studies have shown that the survival rate declines when the duration of CPR is greater than 10 minutes without ROSC and survival rapidly declines to less than .5% after 30 min.3, 4
Cardiac arrests encountered in remote locations encompass those cases that may require special considerations and specialized equipment to move a patient over long distances to a transport capable vehicle, these cases can include cardiac arrest occurring in the backcountry or an arrest on the 110th floor of a skyscraper. Successful resuscitation in the remote setting is dependent on starting quality CPR immediately and not focusing on transport to the hospital. Quality chest compressions require the patient to be positioned supine on a stationary firm surface allowing CPR to be delivered properly. The rush to get a patient to an ambulance while performing CPR on the move can lead to poor airway management and inadequate sometimes harmful chest compressions. Mechanical CPR devices have not been definitively proven to increase survival as compared to manual compressions, but the use of these devices improves safety for rescuers during movement and transport.
Recommendations: Resuscitate in place and consider discontinuation of treatment if no ROSC after 30 minutes of proper basic and advanced life support procedures. Rescue teams should not rush to move a patient to an ambulance, all current science points to remaining on location administering high-quality CPR with early AED integration.3, 4 Moving a patient via stretcher, stokes type baskets, ATV, or small boat over long distances increases the probability of poor compression quality and increased risk of dislodging advanced airways. The early integration of an AED is vitally important and should be part of the standard mobile equipment loadout for a remote medical call.1, 2 Although paramedics can administer medications via IO/IV as indicated, the efficacy of pharmacological therapy during a cardiac arrest has not been shown to improve ROSC-to-hospital discharge rates, ALS is not the priority. However, post-arrest stabilization may require the use of vasopressors and antiarrhythmic medications which have proven their efficacy in treating lethal reperfusion arrhythmias and hypotension making paramedic care important during peri-arrest period of post ROSC care.
Suspension Trauma and Crush Syndrome
Suspension trauma encompasses those victims that are suspended off the ground in a safety harness or rope system without movement for a prolonged period. In theory, the pathophysiology of this type of injury is similar to Crush Syndrome.5 It is speculated that the causes of cardiac arrest in these types of cases are attributed to the inability to respire properly and lack of circulation to vital organs both caused by the anatomical position of the victim and the body’s weight against the harness impeding blood flow and chest expansion.
Other causes of cardiac arrest include the rapid return of acidic blood when the victim is suddenly released from the harness leading to Traumatic Rhabdomyolysis.5, 6 Unfortunately, the probability of survival from a traumatic arrest is even less likely in the presence of systemic acidosis but there is no specific data regarding survival rates from arrest specifically caused by suspension trauma or compression injuries. If by chance the victim is resuscitated, they are likely to suffer some level of renal failure or coagulopathy days after the event.5
Recommendations: Extrication from the harness should not be delayed if the patient is in a state of peri-arrest or cardiac arrest. Conversely, peri-arrest resuscitation begins before extrication with most critical crush injuries.6 Should the patient present with signs of life while still in the harness, paramedic-level rescue techs might consider rapid IV/IO administration of isotonic fluid and sodium bicarb before releasing the suspended victim but only if time and acuity permits.6 If the victim is extricated in full arrest, resuscitate in place. ALS personnel should consider aggressive fluid resuscitation to address acidosis and prevent renal failure.6 Paramedics may elect to administer sodium bicarbonate and calcium chloride to counteract gross systemic acidosis and hyperkalemia which can be sometimes identified by peaked T-waves and/or an abnormally wide QRS on the patient’s ECG.5, 6
Exposure to cold and wet environments for prolonged periods can result in cardiopulmonary arrest from hypothermia secondary to the failure of the heart’s electrical system – including its cardiac pacemakers and conduction system. Cardiac arrest can most certainly occur with core temperatures below 86o Fahrenheit. It is important to remember that a good number of critical care physicians theorize that the heart will not likely react to external defibrillation or pharmacological therapy until the core temp is above 90o– 94o Fahrenheit. Therefore, serial aggressive defibrillation and rapid repetitive administration of epinephrine in an attempt to convert lethal refractory rhythms is not advised. If the patient does not respond to treatment, think it’s hypothermia and rewarm before repeating ineffective measures. Although this rule has never been definitively proven in the civilian sector, it has been adhered to by the military special operations community since the early 1990s.
AHA ECC Recommendations: Remove the victim from the environment and initiate aggressive warming procedures. Resuscitate in place with CPR and heated oxygen if available. The early application of an AED is still recommended, however ventricular fibrillation caused by hypothermia can be refractory to counter shocks.2 Overaggressive serial defibrillation is not encouraged until the patient is rewarmed; judicious defibrillation is recommended regardless of body temperature.2 ALS personnel should initiate IV/IO access using a site that is proximal to the heart and administer warm IV fluids.
It is important to remember that the syndrome known as “Afterdrop” is not a consideration during cardiac arrest resuscitation. Aggressive pharmacological therapy such as serial administration of epinephrine every 3-5 minutes is not stressed until the patient is warmed and metabolism improves.1 The mountain rescue mantra that “you’re not dead until you’re warm and dead” serves as a reminder that prolonged resuscitative efforts are indicated for these cases even if ROSC is not obtained within 30 minutes.1, 2, 6
Electric Shock and Lightning Strikes
Cardiac arrest caused by natural or man-made electricity is primarily caused by electrical current interfering with normal cardiac function – sometimes causing lethal arrhythmias or extensive internal tissue damage. In resuscitation cases involving ultra-high voltage injuries or lightning strikes, providers should have a high index of suspicion that the patient has suffered catastrophic internal trauma.2, 6 Head and spinal injuries are probable with lightning strikes also.2 Typically, most high-voltage injuries have some type of significant burn either externally, internally or both.
Recommendations: Remove the victim from the hazard and pay special attention to scene safety as well as environmental factors. Antiarrhythmics may be indicated during peri-arrest, making ALS care an early priority.1,2 Resuscitate in place and consider termination of treatment if no ROSC after 30 minutes. Consider spinal immobilization if indicated. If ROSC is obtained, the patient should be transported to a burn center unless otherwise directed by medical control. Depending on the size of the electrical burns, prophylactic fluid administration post-resuscitation may be indicated. If the patient is resuscitated do not forget about the administration of pain control medication even if the patient is unresponsive or chemically paralyzed.
Cardiac arrest caused by drowning is a hypoxic event.2 Drowning victims usually have definitive lower airway compromise as fluid impedes gas exchange leading to respiratory arrest that causes cardiac arrest. Prolonged submersion can lead to respiratory and systemic acidosis. Cervical spine trauma is no longer prominently associated with submersion events as less than .5 % of cases have C-spine injuries.2, 6 There is no difference in treatment during resuscitation for saltwater-vs.-freshwater drowning; prolonged submersion greater than 10 minutes in either medium dramatically decreases survivability, unless the victim is very young and suffered a rapid submersion in ice-cold water.2, 6
Recommendations: Remove the victim from the water and resuscitate in place on dry ground, and consider discontinuing treatment if no ROSC after 30 minutes unless the submersion occurred in ice-cold water.2, 6 Treatment should focus on the hypoxic origin of the event which dictates the need for aggressive BLS airway management with suctioning and ventilation with 100% FiO2 and peak end-expiratory pressure (PEEP). Advanced airway placement early in the resuscitation is also recommended.2. ALS personnel may consider sodium bicarbonate if systemic acidosis is suspected but its efficacy in drowning cases is unknown and is no longer considered a standard prophylactic intervention. However, a sustained and elevated EtCO2 may indicate the need for sodium bicarbonate.
The cause of cardiac arrest following a SCUBA diving accident is most likely due to arterial gas embolism (AGE) impeding pulmonary circulation or impeding cerebral blood flow causing unconsciousness leading to drowning. Cardiac arrest caused by pulmonary AGE has a near-zero rate of survival. There is no particular position for the body that prevents the AGE from migrating and becoming a life threat following a SCUBA accident. EMS providers should position the patient to effectively manage the airway. It is also important to obtain the victim’s dive profile for the hyperbaric chamber when applicable.
Recommendations: Resuscitate in place on dry ground and consider discontinuing treatment if there is no ROSC after 30 minutes of proper basic life support and advanced life support procedures. The Diver’s Alert Network (DAN) recommends the position of choice for a dive accident is supine. Consider treating the arrest as a drowning case and address the possible hypoxic origin early. If ROSC is obtained or transport is indicated the destination of choice would be a hospital equipped with a staffed-hyperbaric chamber. As a general rule, most dive chambers in the United States will not accept nor treat a victim in cardiac arrest. DAN’s assistance in determining destination and chamber location is an invaluable resource for prehospital providers and rescue teams.
The overall consensus that still permeates some of America’s biggest EMS systems is that transport still takes priority over on-scene management of cardiac arrest. Numerous studies, as well as recommendations from the AHA, say differently. With the advent of SARS CoV-2, transport is a life-threatening situation to providers. A combination of high-quality uninterrupted compressions coupled with proper oxygenation and early integration of an AED can make all the difference in the world but in special situations. The key to resuscitating a patient is addressing the cause of the arrest early, preferably before the patient irreversibly decompensates.
Generally speaking, patients who suffer cardiac arrest should be resuscitated in place as long as scene safety and environmental conditions permit.3,4 The transport of trauma induced arrest has become more of a priority these days when the trauma center is ranked at a Level II or above and it is within 10-15 minutes of the scene. When treating a cardiac arrest under unusual circumstances rescue technicians, firefighters, and EMS providers alike should consider the events that may have led to cardiac arrest to determine priority and probability of transport.
Gathering relevant information is one of the key factors in forming a good differential diagnosis which can determine the prioritization of transport-vs-continued on-scene care. Although hospitals offer advanced procedures and a higher level of intensive care, sacrificing quality CPR and delaying other treatment to prioritize transport is not conducive to ROSC, nor does it improve victim survival in most cases of non-traumatic cardiopulmonary arrest.
- 2020 AHA ECC Guidelines 2020-Part 3- Special Circumstances of Resuscitation-published via the web 8/2020 https://professional.heart.org/en/science-news/2020-aha-guidelines-for-cpr-and-ecc/top-things-to-know
- 2010 AHA ECC Guidelines – Special Circumstances of Resuscitation, Section 12 https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.110.971069
- EMS Termination Of Resuscitation And Pronouncement of Death C. Libby R. Skinner NCBI StatPearls published and updated 10/27/20. https://www.ncbi.nlm.nih.gov/books/NBK541113/
- Association of Intra-arrest Transport vs Continued On-Scene Resuscitation With Survival to Hospital Discharge Among Patients With Out-of-Hospital Cardiac Arrest. Published by NCBI pubmed 9/15/20 JAMA.2020;324(11):1058–1067. doi:10.1001/JAMA.2020.14185 https://pubmed.ncbi.nlm.nih.gov/32930759/
- Risks and Management of Prolonged Suspension in an Alpine Harness Robert B. Mortimer MD, Wilderness and Environmental Emergencies 22 77-86 https://www.wemjournal.org/article/S1080-6032(10)00320-0/pdf
- PHTLS – Prehospital Trauma Life Support 9th Edition, published by JB Learning 2018 ISBN 978-1-284-04178-6
- Cervical Spine Injuries Associated with Submersion Victims (abstract) Public Med, RS Watson and P. Cummings published on the web https://pubmed.ncbi.nlm.nih.gov/11586155/