ACLS: CLINICAL PEARLS

If a lone rescuer finds a drowning victim, should the lone rescuer leave the victim to call for help, or begin CPR?

If a (near) drowning victim is found unresponsive, the victim is most likely in respiratory arrest, or in cardiac arrest resulting from hypoxia. For cardiac arrest victims where a respiratory problem is the likely cause, it may be more beneficial to provide some CPR (about 2 minutes) prior to leaving the patient to call for help and retrieve an AED. Keep in mind that this scenario is uncommon – most cardiac arrest patients have a cardiac etiology. Furthermore, the rescuer often does not need to leave the victim to call for help – sending a bystander for help or using a mobile phone can allow the rescuer to summon help without leaving the victim.

For how long should a patient be resuscitated before resuscitative efforts are terminated?

There is no blanket answer to this question, as each case will be different. While brain death will begin within a few minutes of cardiac arrest if no resuscitation is provided, in many cases high-quality CPR can allow for neurologically-intact survival even after prolonged resuscitation.

Factors to consider when deciding if resuscitative efforts should be terminated include:

• Assess for obvious signs of death, such as rigor mortis and dependent lividity.
• Determine if the patient has a do-not-resuscitate (DNR) order or other advanced directive.
• Assure that high-quality CPR is being performed.
• Review the ACLS care provided, and search for and treat possible reversible causes of arrest.
• Seek input from the resuscitation team to determine if anything has been missed, or if there are other suggestions prior to terminating efforts.

The new Guidelines call for immediate CPR after defibrillation, without stopping to check for a pulse. Won’t this be harmful if the patient has a return of pulses?

No, this is not harmful and is likely helpful, even if a pulse is present. When defibrillation is successful and an organized rhythm is present, pulses are unlikely to be palpable in the moments after defibrillation. Beginning CPR without checking for a pulse provides immediate CPR if defibrillation was unsuccessful, and provides support of circulation if defibrillation was successful.

When an organized heart rhythm returns after defibrillation, it takes time for the heart to generate enough circulation to sustain a palpable pulse. Providing chest compressions during this time will not cause arrhythmia, and does not harm circulation if the heart is pumping. In fact, studies suggest that chest compressions will boost circulation during this critical time, making ROSC more likely to occur.

Should all ROSC patients receive an antiarrhythmic to prevent further arrhythmia?

The ACLS guidelines focus on initial resuscitative efforts, and there is no recommendation to administer an antiarrhythmic to all patients with ROSC. Immediately after ROSC, use the post-arrest care guidelines to optimize ventilation and oxygenation, and support circulation. Administration of an antiarrhythmic may be helpful for patients with recurrent arrhythmia, or frequent ectopy. If an antiarrhythmic was given during arrest, consider starting a maintenance infusion of the medication that was used. This is a good example of a situation where you should consider seeking “expert consultation” to guide further care.

Should a bradycardic patient receive sedation prior to initiating transcutaneous pacing?

While transcutaneous pacing uses a much smaller amount of energy than other electrical therapy, such as cardioversion, this procedure will still cause pain and discomfort. If the patient is stable enough to safely receive medication, giving a sedative or analgesic prior to initiating pacing may be considered. If not, be prepared to administer a sedative and/or analgesic shortly after pacing is successfully started. The timing of medication administration will depend upon the patient’s condition, mental status, and comfort level.

Should a patient with unstable tachycardia receive sedation prior to synchronized cardioversion?

When using the ACLS guidelines, synchronized cardioversion is always being used for the treatment of an unstable patient. Because the unstable patient may have altered mental status, hypotension, and serious signs and symptoms, the administration of sedation before cardioversion is controversial. The patient’s instability and the need to act quickly are two concerns with administration prior to cardioversion. On the other hand, cardioversion is expected to be successful and quickly stabilize the patient’s condition. The ACLS guidelines to not take a firm stance on this issue; you may consider giving sedation/analgesia prior to cardioversion if it can be administered safely without delaying care.

If a patient has an implanted pacemaker and/or defibrillator, can they still receive external defibrillation (or cardioversion)?

Patients with implanted devices, such as a pacemaker or internal defibrillator (AICD), should be treated using standard ACLS guidelines. Most implanted cardiac devices are located in the upper left chest or the abdomen, and will not interfere with paddle/pad placement. If you identify an implanted device where you would normally place the defibrillation paddles/pads, adjust your placement away from the device, or consider an alternative placement (i.e. Anterior – Posterior).

I heard that patients in un-witnessed cardiac arrest should receive CPR prior to defibrillation, what do the guidelines recommend?

The guidelines recommend applying the AED or defibrillator as soon as it arrives.

There are several recent studies investigating whether a set period of high-quality CPR would improve defibrillation success for patients with a prolonged downtime and no bystander CPR. While these studies had promising results, there was insufficient evidence to warrant a Guidelines change at this time. A period of CPR prior to defibrillation may be considered if you are working in a system with a specific protocol in place, otherwise, you should attempt defibrillation as soon as possible for all patients in VF/VT arrest.

Should cricoid pressure be applied during CPR to prevent gastric distention?

The routine use of cricoid pressure is no longer recommended. Recent studies showed that rescuers frequently apply cricoid pressure incorrectly, and that aspiration may occur even when cricoid pressure is properly applied. Routine use of cricoid pressure may delay or interfere with effective ventilation and airway management. Cricoid pressure may be used to assist with visualization of the vocal cords during intubation.

What happened to the precordial thump? Can it still be used if I witness VF/VT?

The precordial thump involves striking the patient in the center of the chest with a closed fist, with the goal of correcting VF or pulseless VT. Striking the patient’s chest does generate a small electrical impulse that could possibly interrupt an arrhythmia. However, the success of the precordial thump has only been demonstrated anecdotally in case reports – there are no studies supporting its routine use. Routine use of the precordial thump is likely to delay prompt defibrillation.

The current guidelines allow for healthcare providers to consider a precordial thump when VF/VT is witnessed in a monitored setting AND a defibrillator is not readily available. Routine use of the precordial thump is not recommended!

Cardiac arrest patients are often acidotic, should Sodium Bicarbonate be given to all cardiac arrest patients to treat for acidosis?

No, routine or prophylactic administration of sodium bicarbonate during cardiac arrest is not recommended. While acidosis is common during cardiac arrest, this is typically a respiratory acidosis. Respiratory acidosis is best treated by restoring adequate ventilation. Sodium bicarbonate therapy should be reserved for suspected metabolic acidosis, usually when metabolic acidosis is considered a possible reversible cause of arrest.

I was told to try defibrillating asystole in case the patient was in fine VF… It can’t do any harm, right?

Defibrillation is used to interrupt disorganized electrical activity – asystole is the absence of electrical activity, therefore defibrillation will not help correct asystole. It is true that you should verify asystole by checking ECG connections, looking at more than one ECG lead, and checking the gain (size) of the ECG waveform. However, if the patient is clearly in asystole, defibrillating will not help, and may be harmful. Defibrillating asystole may decrease the likelihood of a spontaneous rhythm returning.

The new guidelines call for titrating oxygen delivery to pulse oximetry of 94-99%. Does this mean high-flow oxygen should not be used during resuscitation?

No, the guidelines still recommend using high-flow oxygen during initial resuscitation for adult patients. Once ROSC occurs, then oxygenation should be optimized by titrating oxygen delivery to maintain pulse oximetry between 94 – 99%.

Why do the guidelines call for titrating oxygen to a pulse oximetry of 94-99%? Why not 100%?

Pulse oximetry is the easiest way for us to assess patients’ oxygenation, however it is not without limitations. Pulse oximetry attempts to measure the percentage of red blood cells that are oxygenated – it does not directly measure the amount of oxygen in the circulatory system. Therefore, a patient with normal oxygenation may have a pulse oximetry value of 100%, and a patient that is receiving too much oxygen (hyperoxia) will also have a pulse oximetry value of 100%. We can avoid hyperoxia by titrating oxygen to a pulse oximetry range of 94-99%.

Why do patients with polymorphic ventricular tachycardia (or torsades de pointe) receive unsynchronized cardioversion?

Synchronized cardioversion depends upon the monitor/defibrillator recognizing the QRS complexes of the tachyarrhythmia. If the monitor/defibrillator cannot recognize (“Sync” with) the QRS complexes, attempts at synchronized cardioversion may result in delayed energy delivery or failure to delivery energy at all. Polymorphic VT by definition has QRS complexes of varying size and shape, which are difficult for the monitor/defibrillator to recognize. Polymorphic VT (or torsades de pointe) is the only rhythm treated with unsynchronized cardioversion.

Why shouldn’t I check for a pulse after defibrillating?

The goal of defibrillation is to interrupt ventricular fibrillation or tachycardia, to allow for an organized rhythm to return. When an organized rhythm returns after defibrillating, it is unlikely the patient will have a palpable pulse immediately. When the heart starts beating again, it takes time for the heart to get blood circulating normally again. Providing CPR immediately after shock delivery helps maintain circulation, and helps prevent the patient with an organized rhythm from going back into an arrhythmia.

A patient is receiving synchronized cardioversion, and they develop ventricular fibrillation upon shock delivery. What should be done first – CPR or defibrillation?

If cardioversion results in pulseless VF/VT, follow the Cardiac Arrest algorithm. For any patient in pulseless VF/VT, immediate defibrillation is needed. Begin chest compressions, if possible, while preparing for defibrillation. Do not wait for 2 minutes of CPR to be completed; defibrillate as soon as possible.

What happened to “stacked shocks” for defibrillation?

Evidence shows that defibrillation is most effective when the time between stopping chest compressions and delivering the shock is minimized – the goal is less than 10 seconds. Providing “stacked shocks,” without CPR in between attempts, is less likely to be successful and reduces the amount CPR provided.

Can medications be given through the endotracheal tube if vascular access is not available?

Endotracheal administration of medications is a last resort option for some medications, including: Epinephrine, Atropine, Lidocaine, Naloxone, and Diazepam. If the endotracheal route is used, consider doubling the normal IV dose. However, there are no studies demonstrating that endotracheal administration is beneficial. Additionally, with the increased availability of IO devices, the use of the endotracheal route should be a rare occurrence!

Is intraosseous access (IO) as effective as a peripheral IV during resuscitation?

Drug delivery via an intraosseous (IO) device is similar to drug delivery through a peripheral IV. Medications given through an IO should be given at the same dose as through a peripheral IV. Medications with an extremely short half-life, such as Adenosine, may be less effective through an IO depending on where the IO device is placed.