Cardiac arrest in the OR under anesthesia is fortunately rare.  The total number of OR procedures performed globally last year was 313 million. The incidence of intraoperative cardiac arrest has been quoted as less than 0.1%. However, a small percentage of a large number is still a fairly significant number, in this case 313,000 per year. Getting prepared for rare events is often more challenging than preparing for regular events. When a rare event happens, it can induce shock and fear. This fear can erase protocol from the most prepared mind. Let me share some of the things that I’ve learned over almost 45 years of OR emergencies.

Always Assume An Alarm Is Real Until Proven Otherwise

Recognizing cardiac arrest in the OR may not be easy. The vast majority of times that our alarms go off in the OR, they are false alarms. A lead has become disconnected and is mimicking asystole. The cautery device is producing interference that looks like V-tach. The pulse oximeter is off the finger. The end-tidal-CO2 sensor has gotten plugged with moisture. I could go on. Yet, and this is a huge “however”, sometimes the alarms are real.

I was once on a third world medical volunteer trip. During this trip, the anesthesiologist spent precious minutes troubleshooting the loss of a pulse oximeter reading. He thought he had a mechanical failure. In reality, he had a patient in cardiac arrest. We did successfully resuscitate the patient.

The trap of ignoring an alarm can happen to anyone. Never assume that an alarm is false. I tell my students “don’t just look at your monitors, look at your patient”. Feel for a pulse, listen for heart tones and breath sounds, look at patient color. Never troubleshoot the alarm before checking your patient. The devices are there to help us, not replace us. We are the most important monitor in the room.

Warning Signs of Intraoperative Cardiac Arrest

What are some of the monitor signs of patient arrest in the OR? What indicators suggest that the patient could potentially arrest?

• EKG with pulseless rhythmVentricular Tachycardia [V-Tach]
• Ventricular Fibrillation [V-Fib]
• Severe Bradycardia
• Asystole
• Loss of Carotid pulse > 10 seconds
• Loss of End Tidal CO2 on capnograph
• Loss of Arterial line tracing
• Loss of waveform on pulse oximeter

If you see something worrisome on the monitors, start with your patient.

Tips About Managing Cardiac Arrest In The OR

Emergency Check Lists

I’m not going to review the BLS/ACLS guidelines here. Needless to say preparation involves knowing those protocols. As I said earlier, however, fear can erase a protocol from even the best prepared mind. My OR has printed and laminated check lists for management of serious complications which fortunately rarely happen. These include cardiac arrest, malignant hyperthermia, severe hemorrhage, airway fire, among others. Being able to reference these lists in an emergency is helpful in making sure a critical step is not forgotten. Consider making lists such as these available.

Work The Differential diagnosis

Again, I’m not going to review all of the possible causes of cardiac arrest in the OR. These causes, of course, include preexisting comorbid patient conditions. But I am going to remind you of rare events that are more unique to the perioperative environment. You must think about these events to diagnose them. These events include:

• respiratory arrest from opioid overdose
• hypoxia from loss of the airway, accidental extubation, laryngospasm
• reaction to anesthesia: allergic, malignant hyperthermia, sensitivity
• anesthesia too deep for level of stimulation
• vasoactive infusion running too fast
• complications of surgery, such as acute blood loss or organ injury
• air embolism or pulmonary embolism
• tension pneumothorax, either from surgical complication or barotrauma
• cardiac tamponade, from central venous access or surgical complication

If you don’t imagine something could happen, you won’t diagnose it quickly enough to help. Managing cardiac arrest out of hospital or the ward is challenging. In the OR, consider the unique things that can cause cardiac arrest. If you don’t think of it, you won’t diagnose it in a timely fashion.

Have The Gurney Outside the OR for all Prone and Sitting Cases

Turning the prone patient supine onto a gurney is easier. This is more manageable than rotating them on the OR table. Time is critical. You do not want to wait for a gurney to be brought from preop or the recovery room. Always keep the gurney outside the OR if your patient is prone.

Call for Crash Cart/Defibrillator Early

Call for the crash cart and defibrillator as soon as you become concerned that the patient is becoming unstable. Even if you never need it, having it close by will save critical minutes if the patient does decompensate. It will also prevent you from having to send one of your assistants out of the room. This could happen just when you need your OR nurse the most.

Secure the Airway

If the airway is not secured you must secure it. This can be difficult depending on surgical positioning. Optimize head and neck position as best you can.

Asking for Help Is a Sign of Strength

We all have a tendency to wait before asking for help. We believe we can manage the issue ourselves because most of the time we can. Denial is common: surely this can’t be happening —it must be a mechanical malfunction. We may be worried someone will think poorly of us if we ask for assistance.

We have all experienced that queasy feeling in our gut. It tells us that things are happening too fast. We aren’t quite in control. We don’t know exactly what is going on. Listen to that sixth sense and call for back-up. Make sure your surgeon and your OR nurse know you are worried. If you end up not needing the help, thank them for coming and send them away. I tell my students that knowing when to ask for help shows strength. It is not a sign of weakness.

Manage the Anesthetic

Don’t forget to go to 100% oxygen and turn off or down the anesthetic agent as appropriate. In a crisis, little but important things often get overlooked. It’s very easy to forget to turn the anesthetic back on. If the resuscitation is successful, provide some level of anesthesia for pain control. Ensure amnesia until the skin incision is closed.

Who Is Running This Code?

Many us have responded to a cardiac arrest situation where  there were too many people in the room. Multiple providers, from surgeons, to anesthesiologists, to intensivists were all shouting orders. Sometimes in the after-action discussion it turns out that no one person was officially running the code. Key decisions during codes must be made where timing is critical. Someone has to have the big picture. Make sure you know who is running the code or the resuscitation. Don’t be afraid to ask if you don’t know.

The anesthesiologist often runs the code during cardiac arrest in the OR. However, the anesthesiologist will often be tempted to also start extra IVs, give medications, etc. because that’s what we do everyday. If it’s our anesthetic, we will often feel like the anesthetic is still the priority.

Optimally, the person running the code is running the code and not performing other duties. It’s crucial that the provider running the code stays focused. hey must avoid tasks that prevent seeing the bigger picture while running the code. It’s hard to stand back, but it’s essential if you can.

If you don’t have a lot of helpers, running both the code and the anesthetic may be unavoidable. In this case, delegate as much as you can. Ensure that your note taker reminds you of events and key time intervals while working through the algorithm.

Who Should Do Chest Compressions?

The anesthesia team is going to be tempted to do the chest compressions. For an abdominal or chest case this is not advisable. You won’t be able to compress the chest in the optimal location. It will interfere with your resuscitation and running the code.

During cardiac arrest in the OR, it’s acceptable to ask a surgeon to do the chest compressions. Alternatively, you can ask one of the surgeon’s team members. They can do it on their side of the sterile drape. They will most likely have better access to the correct spot on the sternum. This arrangement provides the anesthesia team more space to resuscitate the patient. It also offers less distraction from folks trading places as they place lines, give drugs, etc.

Now, there are also important things that the surgeon needs to do. Control of bleeding comes to mind. You can have someone else other than the surgeon gown. This person can quickly glove to relieve whoever is doing the initial chest compressions. In this circumstance a five minute scrub is not needed: just gown and glove.

Consider lowering the drape to the extent that it is easier to communicate between surgeons and anesthesia team.

Don’t Forget Ongoing Blood Loss!

Speaking of blood loss, don’t forget that it may be ongoing during the code. I was once performing anesthesia for a teenage boy having a T3 to L4 thoracolumbar fusion. Midway through the case the patient arrested due to an air embolism. We immediately turned the patient supine on a gurney, performed CPR and ACLS  and successfully resuscitated him. However, after about 10 minutes of stability the patient once again became hypotensive and developed pulseless electrical activity. In our focus on the arrest — and relief at the “save” — we had forgotten that the boy’s fully open back wound was still bleeding. He had bled several units of blood into the sheets during the code. Rapid transfusion again resuscitated the patient and he went on to recover fully.

Never forget that things related to the ongoing surgery can deteriorate during the CPR. Even those unrelated to the initial arrest can worsen. Once again: big picture.

Check the Defibrillator Pads

Cardiac arrest in the OR is complicated by the surgical field. The chest area may very well be wet with blood, sweat, and other secretions. During CPR, the defibrillator pads may come lose. Keep checking for a good connection before shocking if the code has gone on for a while.

Communication is Key

If it’s too noisy to hear, ask for quiet. It’s okay to ask for unneeded people to leave. Provide a verbal summary of resuscitative steps periodically. This can help keep everyone in the loop. It also allows others to point out suggestions on other things to do or try. Ask for suggestions as the code progresses. Many coordinated brains in an emergency are often better than one.

Resuscitation is Vital, But Don’t Forget the Surgical Field

Avoid contaminating the surgical field if at all possible. While resuscitation takes precedence, preventing infection and other complications is also important. Cover the surgical site. Have helpers doing chest compressions gown and glove. Consider additional antibiotic prophylaxis once resuscitation is successful.

How Do You Know CPR Is Effective?

Start With Your Patient

Look at your patient’s color. Is it improving? Can you feel a pulse with the compressions? Can you hear breath sounds with ventilation?

End Tidal Carbon Dioxide monitoring

It is standard of care in the modern OR to monitor capnography. End tidal carbon dioxide is a critical indicator of chest compression adequacy. It also signals the return of spontaneous circulation (ROSC). Kalenda was the first to report this observation in 1978 and observed that this was helpful in assessing rescuer exhaustion. He noted that performing CPR  improved ETCO2. Over time, as the rescuer got tired, ETCO2 decreased again. Replacing the fatigue rescuer with a fresh rescuer resulted in an improvement in ETCO2. Kalenda also reported the connection between improved ETCO2 and ROSC.

Why does this happen? During a normal ventilatory cycle, we inhale air bringing oxygen into the lungs . Oxygen is picked up and delivered to the tissues via the bloodstream. The blood in the periphery drops off oxygen. It picks up waste product carbon dioxide. This carbon dioxide is delivered back to the lungs where we exhale it. If cardiac output drops and there is inadequate circulation, blood and tissue oxygenation will decrease. Tissue carbon dioxide will increase. However, carbon dioxide delivery back to the lungs will drop. What you will see on your capnograph is that the end-tidal CO2 will abruptly drop.

I see this acute drop of ETCO2 during anesthesia if my patient suddenly becomes hypotensive. As I treat the hypotension, end tidal CO2 rises again, reassuring me that cardiac output is improving.

Keep an eye on the CO2 as an indication of good CPR or of return to spontaneous circulation. It should at least be greater than 10mmHg. Similarly we can use our capnograph to assess CPR. End Tidal CO2 > 20mm Hg on capnography indicates adequate CPR or ROSC. If it’s less than that, improve your compressions.

Of note, an ETCO2 <10mm Hg after 20 min of standard ACLS is associated with 100% failure of ROSC.

Intravascular Monitors

During chest compressions, aim for diastolic pressure of 30-40mm Hg by arterial line catheter at time of full compressions. Coronary perfusion pressure (CPP) should be greater than 15 mmHg. (CPP= Diastolic BP- CVP)

Ultrasonography

Consider using a portable ultrasound or echocardiogram machine to identify cardiac motion. Our ability to feel a very weak pulse is limited. Sometimes what we think is pulseless electrical activity is really severe hypotension and poor perfusion, with persistent cardiac motion. A patient whose heart is still beating has a much higher chance of survival. This holds true even if we can’t feel the pulse. Place the ultrasound probe sub-xiphoid or parasternal. Aim it toward the heart. This can tell you if there is still cardiac motion.

Summary

Cardiac arrest in the OR is challenging both to recognize quickly as well as to treat. You must diagnose the cause effectively. This must be done even with complex anesthetic, surgical, and comorbid combinations. At the same time  you must perform a resuscitation, often in the face of ongoing surgery. To do so successfully requires active imagination and flexibility. Teamwork and excellent communication skills are essential. Knowledge of protocols and the ability to actively assess your patient are crucial. You must also use sophisticated monitoring tools.

May the force be with you

Christine E. Whitten MD, author:

Anyone Can Intubate: A Step-by-Step Guide, 5th Edition
Pediatric Airway Management: A Step-by-Step Guide
Basic Airway Management: A Step-by-Step Guide

Further Reading