The potentially treatable Hs and Ts of cardiac arrest
| Hs: |
| Hypovolemia/Hemorrhage Hypoxia Hyper‐/hypokalemia Hydrogen ion (acidosis) Hypothermia |
| Ts: |
| Toxins Tamponade (cardiac) Tension pneumothorax Thrombosis (coronary) Thrombosis (massive pulmonary) |
Additional therapies
Cardiac arrest represents the ultimate scenario of cardiovascular collapse. Consequently, cardiopulmonary bypass or extracorporeal life support (ECLS) may represent one potential solution. In tightly defined populations, ECLS combined with early angiography and hypothermia therapy has yielded good neurologic outcomes in a significant proportion of patients [84–86]. In a study that used ECLS only after standard therapy failed, the rate of good neurologic outcome was small [87]. Optimal selection of patients for this therapy will require early mobilization of resources, given the association between prolonged arrest and poor neurologic outcomes [88]. ECLS can also be considered in certain toxicologic overdoses resulting in cardiac arrest, such as beta‐blocker, calcium channel blocker, or tricyclic antidepressant overdose [1].
Principles of management
Resuscitation protocols
Cardiac arrest treatment interventions are time critical. Thus, protocols should facilitate prompt initiation of resuscitative efforts. Nonphysician responders should provide initial cardiac arrest care using guidelines and standing orders, as there is inadequate time to consult with a direct medical oversight physician for detailed guidance. The guidelines should detail interventions for the various ECG rhythms likely to be encountered and should provide convenient reference to medication dosages, mixtures, and administration rates. Other practical information should also be included, such as criteria for termination of resuscitation. Many systems use current AHA ACLS algorithms as the basis for cardiac arrest guidelines [1].
EMS personnel should be encouraged to contact the direct medical oversight physician for additional direction after initial successful or unsuccessful resuscitative efforts, as well as for unusual or complicated situations. Due to the time‐sensitive nature of cardiac arrest and the often‐chaotic resuscitation scene, radio or phone interactions with the EMS personnel must be short, directed, and relevant. The physician must understand that detailed medical history or preceding symptoms are usually not known and are largely (although not entirely) irrelevant to the acute resuscitation phase of the patient’s care. Because EMS clinicians’ care is typically guided by protocol or standing orders, calls for physician input are generally for atypical or complex situations not otherwise addressed. Direct medical oversight physicians must be prepared to provide concise direction for these less common situations.
High‐performance CPR: the pit crew approach
Based on the emerging concepts described above, appreciation has developed for the importance of doing CPR in a very high‐quality and more precise manner and for providing the other components of resuscitation in a more measured approach. Achieving these goals requires a team of EMS personnel working together in a carefully choreographed way. Some have suggested that rescuers at a cardiac arrest scene should function like a racing pit crew, each very skilled, with a specific task or tasks, and working in a synchronized manner.
This concept also emphasizes and includes practice sessions on high‐quality performance: assuring continuous chest compressions with proper depth, rate, and recoil, and changing compressors every 100–200 compressions. It means coordinating defibrillation, such as charging the defibrillator with 20 or so compressions left in the cycle, so the operator can quickly assess the rhythm and push to shock as soon as the compressor is off the chest. The first two responders should position themselves on each side of the chest, and while one (EMS1) starts compressions, the other (EMS2) applies the defibrillation pads and turns on the monitor. As EMS1 finishes the first round of compressions, the rhythm is analyzed. If a shockable rhythm is found, EMS2 can defibrillate and then begin chest compressions. Meanwhile, EMS1 is relieved of compressing (for 1 minute), and he or she should insert an oral airway and place an oxygen mask or ventilate with a bag‐valve‐mask. When EMS2 is relieved for his or her minute break, he or she looks for IV or intraosseous access and administers epinephrine. The rhythm should be checked every 200 compressions or every 2 minutes. As more personnel arrive, attention can be paid to ventilation and placement of an advanced airway (endotracheal intubation or supraglottic airway). Finally, the team leader should reassess all ongoing therapies, monitor function, and consider potentially treatable specific conditions.
When to initiate transport
Care during the initial 10‐20 minutes of resuscitation should occur at the location where the patient was found, or an area as close as possible with adequate space (e.g., move to family room from hallway). Efforts to “package the patient” or to transfer the patient to the ambulance compromise resuscitation quality, including timeliness of defibrillation and medication interventions and the quality of chest compressions. A large, multicenter, retrospective study found that continuing resuscitation on scene until ROSC, compared to transporting patients while in arrest, was associated with a three‐fold increase in survival. This association was reversed after about 30 minutes of on‐scene resuscitation, at which point there was a survival advantage to transporting the patient [89]. Moving the patient to the ambulance or transporting immediately, except for some very rare situations, is not beneficial.
In pregnant patients who are >20 weeks gestation or fundal height is above the umbilicus, manual displacement of the fetus to the left is recommended during CPR. Rapid transport of this patient to a facility capable of perimortem caesarian section may provide the best opportunity for survival of both patients (see Chapter 45).
COVID‐19 considerations
In the era of COVID‐19, current recommendations include donning personal protective equipment before performing CPR and limiting the number of personnel involved in the resuscitation [90]. Limiting aerosolizing procedures and using a bag‐valve‐mask with HEPA filter may limit the potential for transmission of COVID‐19.
Withholding resuscitation
Historically, EMS clinicians may have been indoctrinated to be weary of withholding resuscitative efforts. In some cases, appropriate input from family members might have been disregarded. The concern rested on the notion that deciding not to attempt resuscitation is an irreversible decision. On the other hand, attempts can always be abandoned later. However, patient autonomy is an important consideration, and there are times when initiating resuscitative efforts are inappropriate given the clinical circumstances or known patient directives.
The primary EMS situations involving noninitiation of resuscitation efforts include:
The patient has a do not resuscitate (DNR) order (usually a state‐recognized document such as a Physician Orders for Life‐Sustaining Treatment (POLST form); see Chapter 65).
The patient has clear signs of irreversible death (such as rigor mortis).
EMS agencies should have protocols and policies reflecting these situations. Personnel should receive education in the ethical principle of patient autonomy and the local regulations regarding patient directives. In each situation, consultation with the direct medical oversight physician is appropriate. CPR should be initiated whenever the situation is unclear until decision made by the oversight physician.
Bystanders or caregivers may call 9‐1‐1 despite the presence of a DNR order. This may occur because of the lack of knowledge of the patient’s status, uncertainty about the patient’s condition, panic, or simply