Why Young Investigators Should Consider Prehospital Care Research

A car drifts across a double yellow line and slams into an oncoming tractor trailer.  A man collapses on the floor of a supermarket aisle after his heart suddenly stops beating.  A child gasps for breath and begins to turn blue in her mother’s arms as her airway swells in the parking lot of an ice cream parlor.  In each of these cases, after emergency medical services (EMS) are activated by a 911 call, emergency medical technicians (EMTs) jump into ambulances and speed to the scene of these emergencies – major trauma, cardiac arrest, and anaphylaxis, respectively – ready to treat and stabilize critically ill patients. 

As an undergraduate and EMT-B fresh out of class, I quickly realized that there are a wealth of issues in the field of prehospital care that need to be addressed in an evidence-based manner.  Thankfully, I found a wonderful mentor in my university’s Department of Emergency Medicine who steered me in the direction of the right questions and introduced me to methods that can be used to pursue the relevant answers.  However, I am also aware that many undergraduates are not as fortunate as I have been in this regard.  To create change in any field of medicine, it is crucial to 1) have an understanding of the current standard of care treatments provided to a given class of patients 2) develop a physiologically justified question that is answerable using available or collectible data, and 3) obtain an answer that has the potential to improve patient care.  With this article, I hope to be of service by briefly outlining of the role of EMS, providing an example of important research conducted in the field during the past decade, and giving the reader thirty questions that have answers with the potential to save lives and shape the future of emergency medicine.      

Prehospital care has come a very long way since the beginning of EMS in the United States during the mid-20^th century (Shah, 2006).  What started as a system defined by throwing dying patients into repurposed hearses and then racing at high speeds to the nearest emergency room has evolved into a nationwide network of ground and air vehicles stocked with state-of-the-art equipment ranging from electrocardiograms used to analyze the heart’s electrical rhythm to portable ventilators that breathe for patients who can no longer do so on their own.  This system is staffed by healthcare providers rigorously trained to perform lifesaving medical interventions that include chest compressions, defibrillation, hemorrhage control, and the proper administration of pharmacologic agents.  The actions of EMTs have benefitted millions of patients who would not have survived transport to the nearest hospital without the application of immediate medical intervention.

It is indisputable that prehospital emergency care is a vital part of the healthcare system, particularly for the patients suffering from life-threatening illness for which morbidity and mortality has a time-dependent effect.  Out-of-hospital cardiac arrest (OHCA) provides one striking example – for every minute following pulselessness that passes without intervention, the probability of surviving decreases by approximately 10%.  For this reason, until about sixty years ago, every OHCA victim died where they fell.  Then, after the development of portable defibrillators and cardiopulmonary resuscitation (CPR) in the 1960s and the movement of this technology into the prehospital setting, patients began having a chance to survive.  Now, approximately 10% of cardiac arrest victims in the US survive to hospital discharge after treatment in the prehospital setting (Virani et al., 2020).  While infinitely better than the 0% seen previously, it is still a sobering statistic that has seen little improvement over the past decade. 

Despite this, there is hope for these patients thanks to the resuscitation researchers diligently working toward revolutionizing the standard of care we can offer these patients in the prehospital setting.  One of the biggest advances in the past decade was memorably inspired by a case study of bystander CPR performed with a toilet plunger (Lurie, Lindo, & Chin, 1990).  This report (in part) motivated a group of physician-scientists to conduct laboratory research that demonstrated the value of intrathoracic and intracranial pressure (ICP) modulation to improve the success of cardiac arrest resuscitation.  They found that keeping pressure in the thorax low during CPR (by, for example, pulling on the chest wall during the upstroke of each compression with a suction cup/plunger to increase the volume of the thoracic cavity) is important because it maximizes the return of blood to the heart between chest compressions.  Think of the heart as an untied balloon — if it is only one-quarter full, a squeeze will push much less air out (and with much less noise) than if the balloon is full of air when you begin to apply pressure.  Therefore, maximizing blood return to the heart between compressions allows for more forward blood flow and better tissue perfusion.  It is also important to keep ICP low during resuscitation because high ICP resists the movement of oxygenated blood from the pulmonary circuit to the brain.  If oxygenated blood is not effectively reaching the brain, this will worsen post-resuscitation neurological injury.

These findings led to the development of the ResQPOD impedance threshold device (ITD) and the ResQPUMP active compression-decompression CPR device.  The ResQPOD is basically a one-way valve.  Once an artificial airway has been established in a cardiac arrest patient (via an endotracheal tube, which is a plastic tube inserted into the trachea, or a supraglottic airway, which is a device that seals around the anatomy above the trachea) the ITD is attached to the end of the airway.  The valve allows air to be forced out of the patient’s lungs during CPR, but does not allow air back into the chest between chest compressions, which keeps the intrathoracic pressure low and increases the return of blood to the heart.  (Note: Ventilations can still be delivered through the device and into the patient’s lungs, but the volume of air delivered is quicky expelled.)  The ResQPUMP is essentially a suction cup with a handle attached – not dissimilar to the plunger that helped inspire its development.  While CPR is being delivered using this device, instead of letting the chest wall recoil after each compression, an upward (approximately 10-kilogram) force is applied to the patient’s chest wall, which expands intrathoracic volume and therefore decreases intrathoracic pressure.  This device has incorporated a force gauge and metronome to monitor compression quality.  Importantly, these devices work synergistically and were found to generate more neurologically intact survivors than standard care when used together in a large randomized controlled trial (Aufderheide et al., 2011). 

Other active areas of research include the optimization of the delivery of vasopressor and antiarrhythmic agents by prehospital providers (Daya et al., 2020; Kudenchuk, Daya, Dorian, & Resuscitation Outcomes Consortium, 2016), the development of post-arrest neuroprotective interventions (Bernard et al., 2002; Lascarrou et al., 2019), and the creation of methods to allow faster recognition of and better bystander response to cardiac arrests (Andelius et al., 2020; Blackwood et al., 2020).  To quote physician-scientist Dr. Keith Lurie, we are witnessing “the dawn of a golden age of resuscitation.”  Yet, there are many questions that need to be answered before definitive progress can be made, and more people need to be asking them.  Examples of questions that will need to be addressed if we hope to provide the highest standard of prehospital care are provided in the following tables [Tables I, II, and III]. 

Cardiac arrest is only one of the many time-critical conditions that prehospital providers treat every day across the country.  Massive hemorrhage, traumatic brain injury, large-vessel-occlusion stroke, and other conditions continue to cause significant morbidity and mortality that may be lessened by the evidence-based actions of EMTs.  The list of medical emergencies is long, and each carries a suite of questions with potentially lifesaving answers.  We still do not know the ideal methods we should be employing to treat many critical patients, and the debate is ongoing regarding a range of important topics – from the techniques employed to manage patient airways (Wang et al., 2018) to the effectiveness of some of the medications that are administered prior to hospital admission (Coats & Lecky, 2020; Kudenchuk et al., 2016; Soar, 2020).

I strongly encourage all young investigators – from undergraduates to undecided post-docs – to consider becoming involved in prehospital emergency care research.  It is a rich and rewarding field with a myriad of opportunities to rapidly inform the performance of lifesaving interventions used around the world to alleviate the suffering of the sickest patients imaginable.  Every moment we waste, hearts continue stopping, trauma victims continue bleeding, and lives are unnecessarily lost every minute of every day.