Paramedics can perform several different therapies involving direct delivery of electricity to the heart, including transcutaneous pacing, synchronized cardioversion, and defibrillation. In this section, each will be described in the following manner: indications, contraindications, recommended settings or dose, precautions, considerations, and therapeutic process.
TCP is the temporary application of an electrical pacemaker to the chest of a patient. TCP delivers a small electrical current to the heart, stimulating it to beat faster than it already is. It will help the patient reach the hospital in a better overall cardiovascular condition than he or she otherwise would without this procedure.
Indications. Bradycardic rhythm with hemodynamic compromise, refractory to atropine and fluid administration. If the patient is in a rhythm with associated signs of hemodynamic compromise that does not respond to the initial dose of atropine—typical bradydysrhythmias that do not respond to atropine include high 2nd- and 3rd-degree AV blocks and idioventricular rhythms—then move rapidly to initiate TCP.
Contraindications. Bradydysrhythmias without hemodynamic compromise or pulseless bradycardic rhythms. Aggressive treatment of bradydysrhythmias that are not hemodynamically unstable is not warranted because the patient is maintaining blood pressure and mentation successfully, despite the bradycardic rhythm. Although it may seem that a pulseless bradycardic rhythm is the ultimate description of hemodynamically unstable, pacing a person in this condition often is fruitless. For pulseless bradycardic rhythms, instead of TCP, look to treat underlying problems such as hypoxia or hypovolemia along with providing high-quality CPR.
Recommended Settings or Dose. Eighty pulses per minute, 80 mA to start, titrate milliamps to the minimum needed for electrical and mechanical capture.
Precautions. Wet patients and excessively hairy patients. Patients whose chest area is wet, either from perspiration or being in water (shower, bath, pool, ocean, etc.) need to be dried off prior to the initiation of therapy. This step helps prevent arcing of the electricity across the chest and helps the pads adhere more effectively throughout the course of treatment. The hair on a patient’s chest could prevent the pads and electrode gel from making a strong contact with the chest, possibly leading to electrical burns to the patient’s chest or, worse, setting the hair on fire. If a patient with excessive hair is encountered, a recommended practice is to firmly apply 1 set of pads and rip them off, hopefully taking a swath of the patient’s hair with them. Next, place a new set of pads in the newly waxed area and proceed as normal. Shaving also works; however, it takes longer and there is a greater chance of injury to the patient.
Considerations. Pain management and/or sedation in patients who are conscious at the start of the procedure or whose consciousness improves with TCP. There is no hiding it; having electricity course through one’s chest wall cannot possibly be a pleasant experience under any circumstance. In these cases, consider pain management or sedation but not until after obtaining electrical and mechanical capture. Once capture is obtained, the patient’s hemodynamic status should improve by observing better blood pressure and mentation. At that point, the paramedic can address the pain and discomfort caused by the electrical current. This can be accomplished with fentanyl 1 mcg/kg for pain or with 2–5 mg of midazolam. Midazolam is preferred because it not only sedates but also induces amnesia.
Synchronized cardioversion is used to interrupt the cardiac cycle of tachydysrhythmias with the delivery of an impulse of electricity. To reset the heart rate at a lower rate while simultaneously minimizing the chances of setting off a lethal dysrhythmia such as VF, this electrical impulse must be delivered at precisely the right moment in the cardiac cycle. If the electricity is delivered on the first half of the T wave, nothing will happen, and the electricity could serve only to hurt the patient. Similarly, if the electricity is delivered on the 2nd half of the T wave, the heart could be sent into VF or VT, either option potentially leading to death. Therefore, the impulse delivery is synchronized with the QRS complex the heart is already generating. The monitor predicts when the next QRS will fall and discharges the electricity only then. This creates a momentary disruption in the entire cardiac cycle, allowing the heart’s pacemaker to take over at a presumably slower rate, immediately improving cardiac output.
Indications. Unstable SVT, unstable VT with pulses, and unstable atrial fibrillation (AF) with rapid ventricular response. These rhythms are hemodynamically unstable because they are too fast to support viable cardiac output for an extended period of time. Although more stable versions of the same rhythms can and should be treated with medications, unstable rhythms need to be treated more aggressively with electricity to promptly restore effective cardiac output. An unstable rhythm is characterized by any of the following symptoms: dizziness, syncope, altered mental status, hypotension, or orthostatic hypotension.
Contraindications. Stable SVT, stable VT with pulses, stable AF with rapid ventricular response, and pulseless VT. The stable rhythms are treated with a variety of medications. Pulseless VT is treated with defibrillation and medications.
Recommended Settings or Dose. For atrial rhythms (SVT, AF, atrial flutter), start at 50–100 J, with sequential doses increasing to 150 J, 200 J, 300 J, and 360 J. For VT, start at 100–150 J, with sequential doses increasing to 200 J, 300 J, and 360 J.
Precautions. Electrical shock, postcardioversion cardiac arrest, and wet and/or hairy patients. The electrical impulse delivered during cardioversion is much larger than that given during TCP, so the possibility of bystanders or rescuers getting a shock is very real. It is important to “clear” the patient before delivering the shock. This means to announce that the shock is about to be delivered and perform a visual inspection around the patient so that no one is in contact with either the patient or anything the patient is in contact with, including the stretcher, the ETT, or the intravenous line. After the shock is delivered, reevaluate your patient not just for the resulting rhythm and ensure that your patient is not now in cardiac arrest, a possible untoward effect of the treatment. Patients who are wet and hairy should be handled as described in the TCP section.
Considerations. Pain management and/or sedation in patients who are conscious at the start of the procedure and SYNC button deactivation. In these cases, consider pain management or sedation early in the process but do not delay electrical therapy to provide sedation. One option is to have another paramedic prepare and give the medication as the other prepares the patient for the procedure. This can be accomplished with fentanyl 1 mcg/kg for pain or with 2–5 mg midazolam. Midazolam is preferred because it not only sedates but also induces amnesia. Some machines automatically turn off the SYNC button after the synchronized shock has been delivered, whereas others leave it activated. Therefore, if another synchronized cardioversion is needed, make sure the SYNC button is reactivated. Similarly, if a defibrillation is now needed, ensure that the SYNC button is deactivated.
Defibrillation delivers a surge of electricity to a heart that is currently generating disorganized electrical activity in the hopes of reorganizing that activity. The amount of electricity delivered through defibrillation is significantly higher than that used in TCP and cardioversion. This is because in defibrillation, the amount of electricity delivered needs to overcome that which is already present and redirect it, whereas in TCP, just enough electricity needs to be delivered to stimulate a single myocyte to contract, creating a cascade where the rest of the heart contracts.
Indications. VF and pulseless VT. Defibrillation can be used only when the heart is fibrillating and displaying a rhythm of VF. Pulseless VT is treated identically to VF.
Contraindications. Any rhythm with pulses. including AF and SVT; asystole and PEA. A patient with pulses in any rhythm, including VT, should not be defibrillated. AF should not be defibrillated, even though part of the heart is, in fact, fibrillating. SVT can sometimes look like VT if it is conducted aberrantly (through an alternate electrical pathway), but similarly, it should not be defibrillated. In addition, SVT, aberrantly conducted or not, will have pulses. Pulseless VT and VF are shockable cardiac arrest rhythms; asystole and PEA are not. Defibrillation needs the heart to have its own electrical activity to reorganize it into a meaningful rhythm that produces a pulse. Asystole does not have any electrical activity to reorganize. In PEA, the electrical activity is already organized; it is just not producing a palpable pulse for any of a variety of reasons.
Recommended Settings or Dose. Biphasic machines: 200 J to start or the manufacturer’s recommended setting for first and successive doses. Monophasic machines: 360 J, all shocks.
Precautions. Electrical shock, SYNC button activated, patients who are wet and/or hairy. The electrical impulse delivered during defibrillation is much larger than that given during TCP, so the possibility of bystanders or rescuers getting a shock is very real. It is important to “clear” the patient before delivering the shock. This means to announce that the shock is about to be delivered and perform a visual inspection around the patient so that no one is in contact with either the patient or anything the patient is in contact with, including the stretcher, the ETT, or the intravenous line. If the defibrillation shock will not deliver despite the machine being charged and pads making good contact with the patient’s skin, ensure that the SYNC button is not activated. If it is, the machine is waiting to figure out when to deliver the shock. This will never happen because there is no QRS to find in VF. Patients who are wet and hairy should be handled as described in the TCP section.
Considerations. Continuity of CPR. Minimize interruptions in CPR during pulse and rhythm checks or intubation attempts. The continuity of high-quality compressions at a rate of at least 100 per minute and approximately 2 inches deep is crucial to the patient having any chance of survival. After the shock is delivered, immediately resume CPR for 2 minutes unless the patient immediately regains and maintains consciousness.
When a patient achieves ROSC, the paramedic’s new priority is to take steps to prevent a reentry back into cardiac arrest. This is a multistep process that involves stabilizing the heart rate and rhythm, maintaining a viable blood pressure, and maintaining an airway and ventilation if not previously secured.
For patients coming out of a cardiac arrest that at any time during the resuscitation presented with either VF or VT, preventing recurrence of these rhythms is the first important priority. If not done during the resuscitation, administer a loading bolus dose of either amiodarone or lidocaine. Once the bolus has been administered, initiate an infusion of that same medication. For lidocaine, inject 100 mg into 100 mL NSS to create a 1 mg/mL solution and run the infusion at 1–4 mg/min according to medical control’s direction. For amiodarone, the infusion should be run at 1 mg/min for the first 6 hours after ROSC.
Frequently, a patient’s heart will start off slowly and accelerate to a more normal heart rate after conversion from a nonperfusing rhythm. If the patient’s rhythm is bradycardic, consider a bolus of 0.5–1 mg atropine intravenously, especially if the blood pressure is low. If the atropine does not work, initiate TCP for bradycardia with low blood pressure (symptomatic bradycardia).
In stabilizing the blood pressure, first provide a fluid bolus of at least 500 mL prior to beginning more aggressive treatment. This will directly increase preload, which should translate into a higher blood pressure. More than that amount in a short amount of time on an already sick heart could precipitate pulmonary edema and other signs of fluid overload. This is not a case where if some is good, more is better. If a fluid bolus has not sufficiently increased blood pressure to the target systolic pressure of 100 mmHg, the physician may order a vasopressor to be given. The options available to the paramedic are epinephrine and dopamine. Prepare the epinephrine infusion by injecting 1 mg into a 100 mL bag of NSS to create a 10 mcg/mL concentration. Run this at 0.1–0.5 mcg/kg/min and titrate to effect. For dopamine, inject 400 mg into a 250 mL bag of NSS to create a 1,600 mcg/mL concentration. Run this at 2–5 mcg/kg/min to start and titrate to effect up to 20 mcg/kg/min. The effect to which the titration is being performed is an SBP of 100 mmHg. Once that value is achieved, turn down the infusion rates and maintain that blood pressure. Finally, if the blood pressure allows, raise the head of the bed to about 30° to help with cerebral drainage and keep the patient warm as part of the shock treatment plan.
Withholding CPR means either deciding not to provide it in the first place or ceasing efforts once they have begun. A paramedic may encounter 3 situations that will signal that the patient has already been in cardiac arrest for too long to merit any attempts to even begin. First and most obvious is putrefaction and signs inconsistent with life. If the patient has been deceased for so long that they actually have begun to putrefy or rot, nothing can be done. Furthermore, other signs inconsistent with life may be present, such as decapitation.
Second is rigor mortis. Rigor begins to set in approximately 8 hours after death and lasts for about 12–16 hours. During this time, the body is stiff from all the muscles becoming rigid.
The 3rd and final situation is if dependent lividity is observed. Lividity is the pooling of blood in the lowest areas of the body in response to gravity. Lividity begins to be noticeable approximately 30 minutes after death and continues indefinitely because the the heart is no longer pushing the blood around.
These situations are pretty straightforward and easily observable. But, when it comes to deciding when to stop resuscitative efforts after they have been begun—whether by the paramedics, other first responders, or bystanders—it can be much more difficult. There are very few hard and fast rules as to when to stop CPR versus bringing the patient to the hospital. For example, the patient’s family may expect you to bring the patient to the hospital; bystanders similarly may view the paramedics and other responders negatively if they appear to just “give up.” Next to consider is what to do with the body? It is becoming increasingly common to terminate resuscitations in the field rather than waste prehospital and in-hospital resources on a futile effort. The recommendation at this point is that if the paramedic believes that continuing resuscitative efforts will only prolong the inevitable, contact medical control and solicit their input and acceptance. This is particularly true in the following situations: