Cardiac Arrest Management: Part 2
Last month's issue discussed the most recent AHA guidelines' emphasis on improving basic life support in managing cardiac arrest. It is known that high-quality CPR and defibrillation within minutes after collapse improve the chances of survival.1 What is less well known is the effectiveness of advanced therapies to treat cardiac arrests. In fact, traditional advanced procedures, such as advanced airway placement and medication delivery, have not been shown to increase survival to hospital discharge.1 Recent literature has also questioned the efficacy of advanced life support (ALS) for out-of-hospital cardiac arrests.2 It appears that certain advanced procedures may decrease the likelihood of survival if done incorrectly, at the wrong time, or in a manner that compromises CPR and defibrillation.
THE OPALS STUDY
Many difficult questions about the value of ALS in cardiac arrest came to light after publication of articles from the Ontario Prehospital Advanced Life Support (OPALS) study. The study took place in Ontario, Canada, where EMS was delivered by only BLS services in many areas. When faced with requests for money to upgrade the EMS system, the government funded a large clinical trial in several cities to determine the effectiveness of adding paramedics trained in advanced life support.2
One aspect of the study was a three- phase evaluation on the effectiveness of each link of the AHA's Chain of Survival for cardiac arrests: early recognition and calling 9-1-1, early CPR, early defibrillation and early advanced care.
The first two phases evaluated bystander CPR, first responder CPR and an expanded AED program. These programs showed a significant increase in long-term survival, and it was presumed that adding ALS would make the survival rate even higher.2
In phase three, paramedics were implemented in some cities to establish IV access, administer medications and perform endotracheal intubation in cardiac arrests. Survival rates from the earlier phases of the study were then compared to those patients who received ALS care.
The results showed no benefit of advanced life support for long-term survival from out-of-hospital cardiac arrests, and only a slightly higher rate of survival to hospital admission (patients who survived long enough to be placed on life support but later died).2
It should be noted that other aspects of the study showed ALS treatment to be beneficial for certain medical problems. A significantly lower mortality rate was found in the group of patients with respiratory distress who received ALS rather than BLS only.3 While the study showed a questionable benefit for ALSO in cardiac arrests, it may prevent cardiac arrest from ever occurring in some medical patients.
One theory as to why there appeared to be little benefit in cardiac arrest patients who received ALS is that in a system that worked on improving BLS care by responders, good CPR took a backseat to advanced procedures once paramedics were introduced. Based on cardiac arrest data, the OPALS study group recommended that communities allocate more resources to the first links in the chain of survival (early CPR and AED programs) than to early advanced life support.2
THE EFFICACY OF ALS IN CARDIAC ARREST MANAGEMENT
The literature now clearly defines which interventions are most valuable in managing cardiac arrests, as well as which have questionable value. The OPALS trial showed little benefit to advanced life support when it was added to optimized BLS care. Last month, we explored how CPR is already done poorly much of the time, with frequent pauses, inadequate depth and relaxation of compressions, and too frequent and forceful ventilation.1 When CPR is already inadequate, pauses for advanced procedures are even less likely to help.
WHAT REALLY MAKES A DIFFERENCE?
Many advanced procedures performed by ALS providers lack strong scientific evidence, because a number of uncontrollable variables make studying out-of-hospital cardiac arrests difficult. These include variations in patient downtime, inconsistent documentation, variable response times and inconsistent quality of CPR.
So where did the advanced procedures come from? The AHA rates each of its recommendations on a scale, from those supported by a high level of scientific evidence to those whose potential benefits simply outweigh the risks. Most of what is known comes from laboratory animal studies and theory.
While this may seem discouraging, the latest AHA guidelines were agreed upon by an international committee of experts and are supported by more scientific evidence than any previous guidelines. We also know that some of the treatment options available are more important than others. CPR and defibrillation have been proven to help and should never be compromised for other interventions that might help, such as medication administration and advanced airway placement.
ADVANCED AIRWAY MANAGEMENT
Perhaps no issue in EMS today is more controversial than endotracheal (ET) intubation in advanced airway management. Until recently, "getting the tube" was considered one of the most important cardiac arrest interventions. The latest guidelines more clearly define the risks and benefits of advanced airway placement and do not recommend placing them until later in the arrest.
Endotracheal intubation is performed by visualizing landmarks in the patient's throat and passing a tube into the trachea to provide a clear path to deliver oxygen to the lungs and prevent aspiration. Long considered the gold standard of airway management, the procedure brings a high rate of complications when performed by people with inadequate training, little opportunity for practice and inadequate mechanisms to monitor placement.1
The most common complication of intubation is that compressions must often be stopped for several seconds while the procedure is performed. If the patient is difficult to intubate, the benefits of the tube will probably not be worth a long pause in compressions. The pause can be minimized by preparing all equipment before the attempt, stopping compressions only long enough to visualize the landmarks, and resuming compressions as soon as the tube is placed.
Other complications are caused by ventilating too forcefully and too frequently. This results in higher intrathoracic pressure (the bad pressure that lowers cardiac output from CPR) and decreased oxygen delivery to the brain.1
The most serious complication of intubation is not recognizing when the tube is mistakenly placed in the esophagus. Many studies have demonstrated unacceptably high rates of misplaced tubes in EMS, which has led some experts to believe that the procedure should be abandoned altogether.
No one method of confirming placement is 100% reliable, so the AHA recommends using multiple methods. One is to listen for gastric sounds over the stomach on the first ventilation through the tube. If sounds are heard, the tube is most likely misplaced and should be removed. Listen over each side of the chest for breath sounds. Equal breath sounds likely indicate correct placement.
Another confirmation method is to use the esophageal detection device (EDD)—a self-inflating bulb that should be pushed in, then placed over the tube before the first ventilation. Rapid reinflation of the bulb generally indicates correct placement.
One of the most reliable methods of tube confirmation is end-tidal carbon dioxide (ETCO2) detection. A device placed on the end of the tube changes color if carbon dioxide is exhaled, which indicates proper placement. The lack of color change, however, does not necessarily mean that the tube is misplaced. Carbon dioxide may not be detected in patients who have been in cardiac arrest for a long time or have had inadequate CPR.
An even better method of tube confirmation is waveform capnography, which measures the amount of carbon dioxide exhaled in mmHg and displays a waveform on a screen with each breath. If the tube is dislodged, it will appear immediately on the monitor. One study that evaluated the association of continuous ETCO2 monitoring and unrecognized misplaced ET tubes in a regional EMS system that used continuous ETCO2 monitoring showed no misplaced tubes, compared with a 23% unrecognized misplacement rate when monitoring was not used.4
Continuous ETCO2 measurement provides additional benefits for managing cardiac arrest. Waveform capnography provides real-time feedback on how fast the patient is being ventilated, which helps avoid hyperventilation and delivering tidal volumes that are too high. The measurement of exhaled carbon dioxide indirectly shows how effective CPR is. Carbon dioxide is a byproduct of metabolism, and higher readings generally indicate better circulation. If there is a return of spontaneous circulation, the ETCO2 reading may rapidly rise before a pulse can be felt.
OTHER ADVANCED AIRWAY DEVICES
Other available advanced airway devices bring fewer potential complications than intubation. Most common are the dual-lumen airway (Combitube), laryngeal mask airway (LMA) and the King LT. Rather than placing a tube directly into the trachea, they are placed blindly and designed to isolate the trachea for ventilation.
While many consider these devices only as backups when intubation is not successful, they can be placed in less time and ventilate as well as an ET tube. ETCO2 detection can be used to confirm placement and ventilation rate with these devices as well. Any device should be secured according to local protocol, and placement should be reassessed after movement.
CARDIAC ARREST MEDICATIONS
Over the years, the medications delivered to cardiac arrest patients have changed dramatically. Routine repeated doses of bicarb and calcium have been replaced by epinephrine, atropine and amiodarone. A better understanding of the physiology of cardiac arrest has led to specific medications being indicated for specific situations. Like other changes, however, no new medication has significantly increased survival.
The first medication given in cardiac arrest is a vasopressor, which constricts blood vessels so more oxygenated blood can be delivered to the heart and brain during CPR. The first-line vasopressors, epinephrine and vasopressin, have been shown to increase the rate of a temporary pulse return, but not long-term survival.1
Patients in ventricular fibrillation (V-fib) are given antiarrhythmics, which work on the heart's ion channels to stop its chaotic electrical activity. Amiodarone and lidocaine are the first-line antiarrhythmics. They work in different ways and should not both be used on the same patient. Like vasopressors, neither has been shown to improve long-term survival, although amiodarone has a slightly better short-term survival rate than lidocaine.1
For patients in asystole or a rhythm of slow pulseless electrical activity, atropine may be given in addition to the vasopressor. It works by blocking the body's parasympathetic tone that is meant to naturally decrease one's heart rate. While its use is supported by even less evidence, it is not believed to cause harm and provides a theoretical benefit.1
VASCULAR ACCESS AND MEDICATION DELIVERY
The most common method used by EMS to deliver medications is an IV line, which should be as large as possible and close to the patient's core. The antecubital or external jugular veins are both good options for this. Intraosseous (IO) devices provide access to the patient's bone so medications can be circulated through bone marrow. New IO devices have made this option more popular. Delivering medications via the ET tube is no longer recommended.
Remember, an ALS provider should never compromise CPR to establish IV access or administer a medication. All medications should be delivered during CPR to allow better circulation.
A PRACTICAL APPROACH TO CARDIAC ARREST MANAGEMENT
EMS providers face several challenges in running cardiac arrests not faced by other healthcare providers. We work them in uncontrolled, small and often dirty environments, and one ALS provider is often responsible for performing all advanced skills, making every decision and ensuring that CPR is done well. Because cardiac arrests are relatively rare, providers get less practice compared with other complaints. These challenges can be met with a methodical, step-by-step, team approach to all cardiac arrests.
Cardiac arrests attract a diverse group of responders, often from different agencies, and this is not the time for turf conflict. Whether a responding service is private or public, paid or volunteer, everyone must work together, making the patient their first priority. Combined training sessions among responding agencies may help by providing a space to interact and discuss each other's expectations. This is best done before the 9-1-1 call is made.
Ideally, a cardiac arrest should be run by at least four EMS providers, two of whom are ALS-certified. One person assumes the role of team leader, and each team member should have an assigned role. The arrest can then be run in two-minute cycles, with providers changing roles between cycles.
Because more is now known about the physiology of cardiac arrest, treatment has moved away from simply treating the rhythm the patient is in. While these changes are more complicated than once thought, the algorithm to treat them is actually less confusing than in the past. CPR is the most important treatment for any arrest rhythm, followed by defibrillation when indicated; all other interventions are secondary.
Regardless of the first responders' level of training, move the patient to the closest area large enough to run the arrest and perform good CPR.
If the arrest was not witnessed by EMS, Provider #1 should begin chest compressions while Provider #2 attaches the AED and assembles the bag-valve mask. Once it's assembled, Provider 2 should insert a basic airway adjunct and provide two ventilations for every 30 compressions. After two minutes of CPR, analyze the rhythm with the AED and shock if indicated. Providers may then switch roles and continue the cycle. If the arrest was witnessed by EMS, the priority is to defibrillate as soon as possible.
Once ALS arrives (or additional help if ALS is on scene first), one ALS provider will assume the role of "team leader" and the other of "skill medic." This should be determined before arriving on scene.
The team leader assumes responsibility for working the monitor/defibrillator, administering medications, supervising CPR and coordinating role changes. The skill medic first establishes IV or IO access, then assists the team leader with delivering the first medication (1 mg epinephrine or 40 units vasopressin).
After a few cycles of CPR, defibrillation and medication administration, the skill medic should choose the appropriate advanced airway device, confirm that it is in place, and ensure that the patient is ventilated at an appropriate rate. The skill medic is also responsible for securing the advanced airway and ensuring that it stays in place.
During advanced airway placement, the team leader should watch the clock to make sure the attempt is not too long. While there is no recommended time limit, the emphasis should be on minimizing the break in chest compressions while the device is being placed. The team leader may also help place the airway device if the skill medic has difficulty.
Continue to run the arrest in two- minute intervals, using the clock on the monitor as a guide and pausing CPR every two minutes while the compressors change roles. In 10 seconds or less, the team leader should determine if the rhythm is shockable and defibrillate the patient if indicated.
For patients in V-fib, immediately follow the shock with CPR and administer antiarrhythmic medication (1.5 mg/kg lidocaine or 300 mg amiodarone). If the patient is not in a shockable rhythm, resume CPR and choose the next medication.
The team should consider the cause of arrest and discuss what other interventions might be helpful, as well as when to terminate the arrest if no intervention is successful.
TRANSPORT OR TERMINATE?
At some point, the team must decide whether to transport the patient to the hospital or terminate the arrest in the field. If the decision is to transport, the emphasis on continuous CPR provides some insight on when to move. There is currently some movement toward terminating more arrests in the field if transporting the patient is believed to be futile, with literature that demonstrates when it is safe to do so.
Even in the best of circumstances, the quality of CPR will be compromised while moving the patient to the ambulance. Once transport is initiated, CPR done in the back of a moving ambulance has been shown to be less effective than when done on a floor. A study conducted in Norway showed that the amount of time without chest compressions increased during transport, which led the authors to recommend stabilizing patients on scene as much as possible prior to transport.5 Another study comparing CPR done on a manikin on a moving stretcher vs. CPR done on a floor showed that the quality of both chest compressions and ventilations was compromised while on a moving stretcher.6 Unlike many other priority medical patients, it may not be best to "load and go" patients in cardiac arrest. In situations where a BLS crew is considering moving a patient to intercept ALS, this is a good thing to remember, along with the distance from ALS and to the hospital.
The reality is that most patients in cardiac arrest are dead, and nothing can be done to resuscitate them.1 Hospital resuscitation teams follow essentially the same algorithms as prehospital ALS. With good CPR, vascular access and an advanced airway, little can be done in the hospital that cannot be done in the field.
There is research to demonstrate when it is safe to terminate a resuscitation attempt in the field. One study showed it is safe to terminate resuscitation efforts in patients who remain in asystole or PEA after 20 minutes of CPR, vascular access, medication administration and definitive airway management.7 The OPALS study group also looked into this, and determined that field pronouncement was indicated when the arrest was not witnessed, no shock was delivered by EMS, and there was no return of spontaneous circulation on scene.8,9,10 This was true in both patients who received BLS-only care and advanced life support.9,10
The decision to terminate an arrest is never easy. While protocols vary, a hospital base physician is often consulted before the decision is made. The team leader should ask for suggestions on what else can be done, and everyone should be in agreement prior to termination.
It is important to remember the needs of the patient's family while an arrest is being run. It appears that family members are more comfortable being present during resuscitation than healthcare providers are with having them there.1 If enough personnel are available, one should explain what is going on, answer questions and provide emotional support. For better or worse, the patient's family will certainly remember the actions of the people who came to help their loved one.
No field resuscitation should be terminated before the patient's family has been properly informed of the situation. This should be done compassionately and with consideration for their cultural and religious beliefs.1 As more arrests are being terminated in the field, EMS workers would benefit from training on how to convey the news of a loved one's death and possible reactions of family members.
A successfully run cardiac arrest is a team effort built on a foundation of high-quality basic life support that is strongly supported by evidence. Advanced skills play an important role in arrest management, but it is less clear which are most effective and when they should be done. Advanced life support must be performed in a way that does not compromise the foundation of basics.
Bob Sullivan, NREMT-P, works as a paramedic with New Castle County EMS and is a member of the Five Points Fire Company near Wilmington, DE. Contact him via e-mail at Rsullivan@nccde.org.
- 2005 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation 112 (suppl):IV1–IV211, 2005.
- Steill IG, Wells GA, De Maio VJ, et al. Advanced cardiac life support in out-of-hospital cardiac arrest. N Eng J Med 351:647–656, 2004.
- Steill IG, Spaite DW, Field B, et al. Advanced life support for out-of-hospital respiratory distress. N Eng J Med 356:2156–2164, 2007.
- Silvestri S, Ralls G, Krauss B, et al. The effectiveness of out-of-hospital use of continuous end-tidal carbon dioxide monitoring on the rate of unrecognized misplaced intubation within a regional emergency medical services program. Ann Emerg Med 45(5):497–503, 2005.
- Olasveengen TM, Wik L, Steen PA. Quality of cardiopulmonary resuscitation before and during transport in out-of-hospital cardiac arrest. Resuscitation 76(2): 185–190, 2006.
- Kim JA, Vogel D. Guimond G, et al. A randomized controlled comparison of cardiopulmonary resuscitation performed on the floor and on a moving ambulance stretcher. Prehosp Emerg Care 10:38–70, 2006.
- Cone DC, Bailey ED, Spackman AB. The safety of a field termination-of-resuscitation protocol. Prehosp Emerg Care 9(3):276–281, 2005.
- Morrison LJ, Visentin LM, Kiss A. Validation of a rule for termination of resuscitation in out-of-hospital cardiac arrest. N Eng J Med 355(5):478–487, 2006.
- Morrison LJ, Vebeek PR, Vermeulen MJ. Derivation and evaluation of a termination of resuscitation clinical prediction rule for advanced life support providers. Resuscitation 74(2):266–275, 2007.
- Ong ME, Jaffey J. Stiell I. Comparison of termination-of-resuscitation guidelines for basic life support: Defibrillator providers in out-of-hospital cardiac arrest. Ann Emerg Med 47(4):337–343, 2006.