Lecture Notes
Background
The big picture in the initial approach to critical care is to make sure you perform actions that will buy you more time to think. When your patient is pulseless you have no time to obtain a history, perform a thorough physical exam, look things up on your phone, etc. Don’t even bother grabbing your stethoscope. Neither a lab value nor an X-ray will help you here. You must perform lifesaving critical actions only!
The initial approach to all critical patients is highly protocolized because people smarter than us figured out that performing these initial actions in a sequential and step-wise manner helps stabilize critical (or dead) patients.
This doesn’t mean you won’t get to use your brain and systematically work through a diagnostic differential at a later time, it simply means that in the first few seconds to minutes of the encounter you shut your brain off and perform these protocolized actions. They will serve as your anchor and help ground you in these often chaotic scenarios.
These situations can be very stressful and your mind will be racing to search through your vast catalog of medical knowledge. Your brain can’t help you in the initial stages, put it on pause. It will help you in the moments after you’ve initiated ACLS when you are trying figure out what happened to the patient (like putting together pieces of a puzzle).
Initial Assessment For All Critical Patients
When you are called to the bedside of a patient that is in critical condition or unconscious. Always start with C-A-B (Circulation-Airway-Breathing). Assess these three things in a sequential manner, understanding that you do not worry about the next item until you have addressed the previous one on the C-A-B list:
Check a central pulse (carotid or femoral) for no longer than 5-10 seconds (really 5 seconds).
If you cannot convince yourself there is a pulse, err on the side of caution and start chest compressions.
Don’t worry about being wrong here.
If you were wrong and the patient actually had a very subtle/faint pulse, it is not the end of the world if they got one round of CPR. Whereas if the opposite were true and you hesitated to initiate CPR on a pulseless patient because you thought you may be…kind of… sort of felt a teensie… tiny little pulse…maybe. Well, you have just caused this patient harm because you delayed initiation of CPR, thereby worsening their ultimate outcome. It’s a high stakes game, always err on the side of performing CPR.
If no pulse start CPR and start the ACLS pulseless arrest algorithm (do not move on to assess the A or the B in C-A-B until you address the C with CPR; If there is a pulse move to the next item.
Assess the airway for obstruction.
Determine if it is patent (you will usually do this in unconscious patients). Sweep the tongue, take a quick look inside to make sure there isn’t a food bolus or FB obstructing it.
If the patient is awake and able to phonate (i.e. talk back to you) their airway is likely protected.
If the patient has no stridor, muffled voice, or snoring the airway is likely patent.
If the airway is NOT patent, troubleshoot, sweep the tongue to inspect, suction, perform a head tilt/jaw thrust/chin lift maneuver, insert oropharyngeal airway (or nasopharyngeal airway), etc.
Breathing: look for equal chest rise, auscultate at bilaterally at the axilla, assess work of breathing.
Perform your C-A-B in all patients until it becomes second nature, in awake patients this assessment takes a few seconds. In unconscious patients, it will help you determine the severity of disease.
OMG The Patient Has no C (i.e. Pulseless Arrest)
Don’t panic, the patient is already dead. There aren’t different levels of death (i.e. mild death, moderate death, or severe death). With your help, the situation only gets better from this point. Patients in arrest have very high mortality and it is your job to give your patients the best shot at survival by focusing on the critical actions that are evidence-based.
Buy yourself time to think by initiating the ACLS algorithm with the help of your code team. Remember you are the code team leader. You are the general overseeing the battle and you must direct (i.e. delegate) other people to perform the critical tasks you need. This will depend on the size of your team, but in an ideal scenario, you delegate all tasks (I usually don’t delegate the pulse check, but this is personal preference). The purpose of delegating tasks is to free up your brain to think critically and to constantly assess, troubleshoot, or provide feedback to your team. Ensure that each member of your team is performing their tasks appropriately. It may be odd at first because you may not have the confidence of experience and you may be younger than the people you are directing, but you must be confident. To avoid confusion, if there are multiple MDs in the room, make sure to establish who will be “running” the code. Once that is established, all orders must flow through the code team leader.
There are only two critical actions you must perform in these scenarios. It may feel like there is a lot you can do but in reality, there are only two critical actions. If these two critical actions are not being performed, then you have to stop everything and re-direct the room to perform them in a sequential manner. The rest of the ACLS algorithm is just fluff.
The Only Two Things That Matter In A Code
To understand what matters in a code, we must first understand the purpose of the ACLS algorithm. The goal in these situations is not just to restart the heart, return of spontaneous circulation (ROSC). The overall end goal of codes is to restart the heart AND to get the patient back as close to their baseline neurologic status as possible. The overall end goal is to save the heart AND the brain. With this in mind, there are only two evidence-based critical actions in the ACLS algorithm that improve the clinical outcome we want. We perform the other parts of the ACLS algorithm (the “fluff”) because they don’t hurt and may help us theoretically. However, there is no hard evidence to support their use and you should think of them as extra things you can do. You must never interrupt either of the two critical actions to perform one of these extra things.
The two critical actions are:
Starting CPR as soon as possible.
Not all CPR is created equal, you must perform good CPR (more on this later).
AND decrease the number of interruptions to CPR.
Shock shockable rhythms (Vfib/Vtach) as soon as possible.
This means you must direct someone to place defibrillator pads on the patient (i.e. put the patient on the monitor)
Remember you can only assess a patient’s rhythm when all hands are off the patient and they are not receiving CPR.
That’s it. That is the whole point of ACLS. Those two things.
CPR Primes The Pump
The main purpose of CPR is actually less about re-circulating blood throughout the whole body and more about increasing coronary perfusion pressure (CPP). CPP is the pressure gradient needed for there to be blood flow at the level of the coronary arteries. You perfuse the heart so it has the nutrients to start beating on its own again. This makes sense when you consider that most cardiac arrests are due to coronary artery disease (from acute occlusion of a coronary artery). We know that increased CPP correlates with an increased chance of obtaining ROSC (a CPP of >15 mm Hg is thought to be necessary for ROSC). We also know that it takes 1-1.5 minutes of continuous CPR to build up to an adequate CPP and that CPP plummets with any interruption in CPR. Additionally, we know that longer pauses in CPR are independently associated with decreased chance of survival. All of this adds up to explain why good CPR is important and why it is important to decrease the number of interruptions to CPR. Now you know.
Jumpstarting The ACLS Machine
Once you determined that your patient is pulseless you call a code blue (to get more helpers):
First, point at someone on your staff (hopefully you know their name) and tell him/her to start CPR.
Second, point at someone and tell him/her to place the defibrillator pads and put the patient on the monitor.
Third, point at someone and tell him/her to be your timekeeper and to tell you when you are due for a pulse check (Q2min).
Doing these three things will jumpstart the ACLS machine and put it on autopilot, thereby buying you 2 minutes to think and organize the room so that you can perform the remainder of your ACLS tasks.
Fourth, point at someone and tell him/her to obtain IV access, if they cannot within 2 minutes then they should place an interosseous (I/O) line.
You know that the ACLS algorithm asks for the administration of EPI and you may need to treat Hs/Ts empirically, therefore having IV or IO access is helpful. However, this should never interrupt or delay, or obstruct CPR (the most important thing you can do to save your patient). It is extra.
Fifth, point at someone and tell him/her to get to the head of the bed and be in charge of the airway. To provide synchronized breaths via BVM (30:2) if there is no advanced airway or asynchronous breaths if an advanced airway is in place (10 breaths/min).
CPR should never be interrupted to obtain advanced airway. You can go through the whole code without obtaining advanced airway.
At this point, you sit back and observe that everyone understands and is performing their assigned task (remember to enforce closed-loop communication).
Now that the ACLS machine is running and on autopilot, it is your job to think about what may be going on AND to begin to gather data that will help you obtain ROSC:
Obtaining information from EMS or other providers.
Was this a witnessed arrest?
When was CPR initiated?
What was the initial rhythm? If ACLS was started before you arrived.
What were the patient’s symptoms prior to arrest?
What is patient’s pmh?
During the 2-minute intervals between pulse checks, you should be gathering this data while simultaneously ensuring that nobody “messes” with your code. For example, you will be assessing to make sure that good CPR is being performed, focusing on minimizing the number of interruptions to CPR (see more on good CPR below). Make sure that the patient is attached to the defibrillator, ask for ETCO2 monitoring if possible, etc. That is your busy work while you wait for your timekeeper to instruct you to perform a pulse check.
The Pulse Check
This should take no more than 5 seconds (important to decrease the number of interruptions to CPR). If there is no obviously palpable pulse, then assume there is no pulse. The second CPR stops your eyes should be locked onto the monitor to evaluate the rhythm while simultaneously assessing for a pulse. As soon as you recognize the rhythm and you’ve given yourself up to 5 seconds to determine if the patient has a pulse, you must announce it to the room.
If the patient has no pulse, you immediately resume CPR and announce to the room what rhythm you saw.
If the patient has a pulse, then you obtain a set of vitals and initiate post-arrest care.
Is The Rhythm Shockable?
There are only two shockable rhythms:
Ventricular fibrillation (VF).
Ventricular tachycardia (VT).
Every other rhythm will fall under the PEA/Asystole category of ACLS. You have to have these two rhythms memorized. If you are performing a pulse check and you cannot tell if it is VF/VT then you must err on the side of caution. When in doubt, shock it out! Electricity is never the wrong answer, it just may not be the most appropriate treatment. Electricity is a fairly benign treatment, with minimal side effects in a pulseless arrest situation. Not shocking a shockable rhythm and missing VT/VF basically means you didn’t perform one of the only two things that matter in a code. That being said, you do not want to get into the habit of shocking PEA/Asystole. Memorize those rhythms!
If the patient remains pulseless and is in either VF/VT, then you resume CPR, instruct your defibrillator person to charge at 200J, and tell everyone to prepare for a shock. Once the defibrillator is charged, you clear everyone off the patient and deliver the defibrillation. Immediately after defibrillation you resume CPR and tell your timekeeper to tell you when it is time for the next pulse check.
VF/VT: Poquito Boom
Decreasing the time to defibrillation is one of the most important variables for predicting ROSC in witnessed arrest (first 4-5 minutes). The shorter the better. If the patient does not have the pads on or if the defibrillator is not charged, perform CPR until you are ready to deliver the shock.
Biphasic shock at 200J (go big or go home).
Always follow a shock with 2 minutes of uninterrupted chest compressions.
Check rhythm and pulse after shock.
If has a pulse then shift to post-cardiac arrest care.
If no pulse then resume compressions, give 1mg Epinephrine (EPI)
EPI should be given every q3-5 min per algorithm. Just do it q4min or every OTHER pulse check
Check rhythm and pulse every 2 minutes. If patient remained in VF/VT prepare for another shock, consider anti-arrhythmic medication if second shock fails:
Prepare for amiodarone or procainamide for shock-resistant VF/VT.
Polymorphic VT (i.e. Torsades): Magnesium 2g IV, followed by maintenance infusion.
VF/VT survival rates as high as 64%.
PEA/Asystole & Throwing Kitchen Sinks
This is a catchall term for rhythms that do not benefit from a defibrillation. In these situations, you are giving patients empiric treatments upfront without waiting around for labs or other data. You rifle through the 5 “H’s” and 5 “T’s” prioritizing the disease process that you think most likely resulted in PEA/Asystole arrest. For example, if you see that the patient has stigmata of end-stage renal disease (i.e. AV fistula, tunnel cath, or are told they missed HD) then you prioritize treating for hyperkalemia with calcium, insulin, and bicarbonate. However, you don’t stop there. You keep on empirically treating the patient as the code is progressing. If you don’t know what caused the arrest you just give it all, with one exception: Thrombolytics. I typically do not empirically treat with thrombolytics unless there is a compelling reason to believe the patient had a massive PE or maybe after a prolonged code where you have given everything else empirically at least once. Below are the Hs/Ts along with their empiric treatments:
Hypovolemia (give 2L NS)
Hypoxia (Give oxygen via bvm or advanced airway)
Hydrogen ion (give an amp of bicarb)
HyperK/HypoK (look for stigmata of ESRD, give hyperkalemia cocktail)
Hypothermia (check temp, active rewarming, don’t stop the code until person is warm and dead, >32C)
Tension PTX (needle thoracostomy; Just DO IT! Don’t be shy)
Thromboembolism (PE -> tPA in the form of alteplase or tenecteplase; hints of massive PE: acute RV strain on ECG, bedside US)
Thromboembolism coronary (i.e. heart attack)
Tamponade (IVF and pericardiocentesis)
Toxins (accidental OD: TCAs, digoxin, BB, CCB, Cocaine)
PEA survival rate 1.2-14%.
What If Nobody Is Around?
In most scenarios, if there are no people around, you start CPR yourself and perform BLS until help arrives. There is some nuance to this and a lot depends largely on whether it was a witnessed vs unwitnessed arrest. For now, just keep things simple and start BLS until help arrives. You can add layers of complexity or discuss specific scenarios with your attendings once you feel comfortable with the basics.
Saving The Brain: Post-Cardiac Arrest Care
Once you get the heart going you want to do everything you can to save the brain. You do this by avoiding three things that are detrimental to the brain:
Hypoxia
Hypotension
Hyperthermia
All adults without meaningful return of neurologic function after cardiac arrest should be considered for therapeutic hypothermia. The data shows improved neurologic outcome for VF/VT arrest, but your hospital may do it for PEA/asystole as well.
Temperature between 32-36C (although some studies say 36C just fine)
Cath lab for appropriate candidates.
All go to ICU
Miscellaneous ACLS Notes:
How Do Perform Good CPR?
Good CPR has 5 main components:
Compression rate, compression depth, chest recoil (don’t lean), chest compression fraction, and ventilation.
Compression rate = 100 compressions per minute
Compression depth = 2 inches
Allow full recoil between compressions
Chest compression fraction (% time that compressions are being performed during an arrest) -> at least 60% if unprotected airway
Ventilation During A Code
Provides oxygenation but also produces positive intrathoracic pressure impeding preload.
Prior to advanced airway do 2 breathes following each cycle of 30 chest compressions
After advanced airway obtained give 10 breaths/min asynchronously (don’t worry about the 30:2 ratio anymore), enough volume to produce minimal chest rise.
Deleterious consequences of over ventilating:
Cerebral vasoconstriction, decreased venous return, barotrauma
ETCO2
High-quality CPR ETCO2 >20 mmHg
Abrupt, sustained rise in ETCO2 to 35-40mmhg suggest ROSC
Epinephrine
The argument for giving EPI:
Alpha-adrenergic stimulation induced vasoconstriction
Increases coronary perfusion pressure (CPP) and myocardial perfusion during CPR
Arguments against giving EPI:
All data behind EPIs pathophysiologic basis comes from animal models.
B-adrenergic effects undesirable in arrest patients: tachycardia, tachydysrhythmia, increased myocardial oxygen demand.
Reduces microvascular perfusion (particularly brain perfusion)
What good is saving the heart if the brain is dead?!
Overall EPI increases the likelihood of ROSC but does not improve the number of patients with good neurologic outcomes after out of hospital cardiac arrest (OHCA).
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