How proficient would you really be if a code situation occurred? Even while keeping your skills up to date with advanced cardiovascular life support (ACLS) recertification, it's possible for nurses to find themselves out-of-practice. This article outlines the magic numbers associated with ACLS, the tools and medications you'll find in the crash cart, and treatment guidelines to follow in a code situation.
Bradycardia
Let's begin with a bradycardia situation. Here, we encounter one of our ACLS magic numbers: 90. As a rule, a patient with a dysrhythmia who still maintains a systolic BP of 90 mm Hg or higher can receive treatment with medications. But, if the systolic BP decreases to below 90, we have to set up for electrical therapy.
Ideally, crash carts are standardized. The top drawer of the cart has three boxes of atropine; the prepackaged injection in each box contains 1 mg. Give these patients 0.5 mg-or half-of the injection to speed up the heart. This same dose can be repeated, if necessary, every 3 to 5 minutes for a maximum dose of 3 mg.
Atropine isn't effective against advanced heart blocks. However, if the patient is conducting few or no P waves with a ventricular rate in the 30s, his or her BP is likely so low that pacing is indicated. The pacer pads are placed on the patient's chest and back, ideally with the heart sandwiched in between. Set the defibrillator to the pace function, which defaults to a rate of 70 beats/minute. Next, gradually increase the milliamp (mA) setting on the output control until the patient shows a ventricular capture after each pacer spike on the ECG. Leave the setting at 2 mA above that capture point. The patient should now be ready for immediate transfer for more definitive care, such as internal pacing.
Tachycardia
At the other extreme, tachycardia can cause the patient's cardiac perfusion to drop because the heart is beating faster than it's designed to do. This brings us to our next ACLS magic number: 150. A heart rate above 150 beats/minute is the point at which electrical therapy should be considered. Supraventricular tachycardia, rapid atrial flutter, or rapid atrial fibrillation will show a narrow QRS complex on the ECG of less than 0.12 seconds, which equals three of the small 0.04-second squares on the ECG graph. Ventricular tachycardia will have a very wide QRS complex of greater than 0.12 seconds.
It's important to distinguish regular (evenly spaced), narrow tachycardia from irregular, narrow tachycardia because the treatment differs regarding medications and the amount of electricity used. It can be difficult to tell the difference because the QRS complexes appear very close to each other on the ECG. Conditions permitting, a 12-lead ECG should be performed to help determine the exact dysrhythmia.
A quick treatment that can be attempted right away is having the patient perform a vagal maneuver to lower his or her heart rate. A variety of vagal maneuvers exist; the type I used in my ICU career was to have the patient forcefully cough once.
Regular
If the physician decides to treat the dysrhythmia as a regular tachycardia with a systolic BP greater than 90, the first drug of choice is adenosine 6 mg via rapid I.V. push, immediately followed by 20 mL 0.9% sodium chloride solution. The patient's ECG tracing may display a flat line for a few seconds before reappearing at a reduced rate. There are three 6 mg vials of adenosine in the cart medication drawer. After the initial dose is administered, a second dose of 12 mg can be given in the same manner.
Other drugs that can be tried after adenosine are verapamil 5 mg I.V. over 2 to 5 minutes or diltiazem 0.25 mg/kg I.V. The second dose of diltiazem is 0.35 mg/kg. These medications aren't in the cart, even though they're drugs needed on very short notice. The medication drawer contains vials of vasopressin, which is no longer recommended in ACLS. Health systems should consider removing these vials from that spot and replacing them with verapamil vials. Why verapamil? It's more useful in an emergency because there's no drug calculation involved.
If the patient's systolic BP drops below 90 at any point, then place defibrillator pads front-to-back and prepare for cardioversion. A regular, narrow-QRS tachycardia receives 50 to 100 joules biphasic (meaning that the unit delivers electricity in two directions), with the monitor set in SYNCH mode so that the shock is delivered in the proper phase of polarization-repolarization. In this mode, the word SYNCH will appear on the monitor and hash marks will appear over each QRS complex. The physician, time permitting, may elect to give the patient I.V. sedation before the shock. Be sure no one touches the patient during the shock.
Irregular
If the physician decides that the patient is experiencing an irregular, narrow tachycardia, as in rapid atrial fibrillation, then use of adenosine isn't indicated. The first-line medications for this patient with a systolic BP of greater than 90 are verapamil or diltiazem; but again, these aren't readily available in crash carts. The medication that we do have on hand to treat rapid atrial fibrillation is a 150 mg vial of amiodarone.
In the second drawer, the I.V. fluids drawer of the cart, you'll note a 100 mL bag of dextrose 5% solution (D5). You can mix the amiodarone 150 mg in this bag and infuse it slowly by gravity over 10 minutes. If using an infusion pump, your infusion rate will be 600 mL/hr. The idea here is to reduce the rate of ventricular response to the atrial fibrillation. The physician may not want to convert the atrial fibrillation to sinus rhythm at this time because it may put the patient at risk for stroke. However, if this patient's BP drops below 90, then synchronized cardioversion must be considered (200 joules biphasic).
Wide-QRS ventricular tachycardia can also be regular or irregular. In either case, the patient is at risk for a sudden drop in BP. If the patient is still maintaining a systolic BP of greater than 90, he or she can still benefit from amiodarone 150 mg in 100 mL D5 infused over 10 minutes. Consider putting defibrillation pads in place because a regular, wide tachycardia with systolic BP of less than 90 needs 100 joules synchronized. A patient with an irregular, wide tachycardia needs 200 joules unsynchronized. This is because the monitor will have difficulty placing hash marks over erratic ventricular complexes.
Enter epinephrine
One ACLS rule of thumb is to do a carotid pulse check each time the patient has an ECG rhythm change. A patient can show a normal sinus rhythm on the ECG and have no pulse or BP, which is called pulseless electrical activity (PEA). The first action here is to immediately start chest compressions over the bottom half of the patient's sternum at one-third the depth of the chest at a rate of at least 100 compressions/minute. This is necessary because chest compressions only deliver a small percentage of the body's natural cardiac output. During a code, you'll need a second person to take over chest compressions after 2 minutes. In a 2-minute period, the patient should receive five cycles of 30 compressions with two ventilations in between. Compressions shouldn't be interrupted for more than 10 seconds.
Six boxes of 1:10,000 strength epinephrine, 1 mg each, are located along the left side of the cart medication drawer. The dose of epinephrine is the same in PEA, asystole, pulseless ventricular tachycardia, or ventricular fibrillation: 1 mg via I.V. push every 3 to 5 minutes. PEA and asystole aren't shockable rhythms; they're treated with epinephrine and quality CPR while the physician considers why the patient is in this rhythm. Common causes are dehydration, hypoxia, hypothermia, swings in potassium, acidosis, cardiac tamponade, and tension pneumothorax. If the monitor suddenly shows a flat line, check the ECG wire attachments to the patient and check a couple of other leads (ll, lll, and avF), if necessary, to make sure that the patient isn't in a fine ventricular fibrillation rhythm, which is shockable.
Both ventricular tachycardia without a pulse and coarse ventricular fibrillation are defibrillated with 200 joules biphasic. CPR then resumes immediately for another 2 minutes while medications are given. After epinephrine 1 mg I.V. is administered, the next medication to try is amiodarone 300 mg via I.V. push. There are three 450 mg vials of amiodarone in the medication drawer. So, your dose is two-thirds the content of one of these vials. Your follow-up dose of amiodarone is 150 mg I.V., which is the remainder of the vial.
In the medication drawer are also four 100 mg boxes of lidocaine. Some sources indicate that lidocaine is still a good option in the treatment of ventricular tachycardia and ventricular fibrillation, whereas others note that it should play less of a role. The initial dose of lidocaine is 1 to 1.5 mg/kg via I.V. push, which is roughly equivalent to one 100 mg prepackaged injection for an adult patient. A second dose of lidocaine is one-half of the first.
Intubation
If a patient doesn't respond right away to defibrillation, then we have to consider intubation. The bottom drawer of the crash cart contains an intubation tray and assorted endotracheal (ET) tubes. Some medications, such as lidocaine, epinephrine, and atropine, as well as naloxone, can also be given through the ET tube if the patient's I.V. access is challenging or lost. However, the I.V. doses must be doubled if given via the airway and followed by 10 mL of 0.9% sodium chloride solution.
Closing thoughts
To sum up, in ACLS the magic numbers are 90 and 150. A systolic BP of less than 90 mm Hg or a heart rate greater than 150 beats/minute should make us think about applying defibrillation pads to the patient and delivering electrical therapy. If we have QRS complexes on the ECG, we need to know if they're narrow or wide, and regular or irregular. Two rescuers are needed to perform chest compressions. ACLS recertification is important, and this guide to crash carts is another tool that you can familiarize yourself with to be prepared in the event of a code situation.
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