Coronary Artery Bypass Graft (CABG)
Coronary Artery Bypass Graft (CABG)
A CABG is a very common procedure and if you’re working cardiac, chances are you’ll work with fresh CABG’s or people with a history of one. Because of this, this section is going to be a little more robust than others.
What it is
If a patient needs this procedure, it means a coronary artery is compromised to a certain degree. To maintain adequate perfusion to the actual heart muscle itself, the coronary artery (or arteries) must be bypassed. Typically, if this issue is known, medical management is attempted first and then this surgery is the next option if that is unsuccessful.
Essentially, a vessel is used from another part of the body to create this bypass conduit. The left internal mammary artery (LIMA) and the right internal mammary artery (RIMA) are most frequently used because the 10 year patency rate are approximately 80%. The saphenous vein graft (SVG) can also be used, but its 10 year patency rate is closer to 50%. Typically, the LIMA is used for the left anterior descending artery (LAD) because it's the most important vessel to support left ventricular function. So, they’ll snag one of these vessels and put that bad boy on the heart and bypass the compromised coronary artery. Check out this great photo that shows the bypass from the aorta past the blockage so the heart muscle distal to the blockage is able to get adequate blood flow. Amazing!
A patient may have one blockage bypassed, and you’ll hear people say a “one vessel CABG” or see people write “CABG x 1” on their report sheet. Most of the time, you’ll see a 2-3 vessel CABG. The most we’ve seen before is a 7 (OH MY GOSSH!) vessel CABG. The more vessels being bypassed, the more vessels need to be harvested. Those patients will have more incisions on their arms/legs because they had to take vessels for the bypass.
How they present
Some patients will come in for a planned CABG. The decision to do a CABG is made if the patient is not a good stent candidate, have diabetes or multi-vessel disease, left main disease, previous in-stent restenosis, or chronic occlusions not amendable to PCI (percutaneous coronary intervention)
In report, you may hear something to the likes of, “the patient presented to the ED with chest pain, a cardiac cath was performed and it showed multi-vessel disease. A 3-vessel CABG was performed the following day.”
If they’ve presented to the ED and are stable with chest pain, yet we’re still trying to figure out what’s going on (and don’t know they need a CABG yet), they may head up to the cardiac floor to get some additional tests like serial ECGs and labs, and a cardiac cath. They’ll get their diagnostics done, get a cardiothoracic surgery consult, and schedule surgery as soon as appropriate. This may be for the following day or so, while we watch monitor telemetry and labs until surgery.
As the floor nurse in this situation, you’d be preparing them for surgery. You’ll chat about what to expect post-operatively. Things like mechanical ventilation, chest tubes, IVs, and foleys, pain management, coughing and deep breathing, and all that jazz. They may be on a heparin drip before surgery that you’d be managing. You’ll get things done like the clipper-prep, chlorhexidine bath, or whatever pre-CABG protocols your hospital has in place. Typically, night shift is taking care of all of this for the patient to head to surgery first thing in the morning. Once the patient head down to pre-op, they won’t come back to the cardiac floor until they’ve been in the cardiac ICU for (typically) a few days.
Post-operative ICU care
Patients will come up from surgery on a ventilator and the length of time in which they are on the vent depends on how they are doing. It can be as little as 6 hours or as many as multiple days.
They’ll also typically have mediastinal and pleural chest tubes that you’ll be in charge of managing. (Check out the chest tubes module for more information on these). The big thing is to note how much drainage you’re seeing. If you’re getting over 100-150 mL per hour out, that’s quite a bit and the surgeon and/or their advanced practice provider needs to know.
They’ll also have epicardial pacing wires in place. These wires are put in place during surgery because dysrhythmias are common after this surgery and it enables us to “pace” them with a bedside pacemaker, rather than using external pacer pads. Basically, they’ve got a few thin metal wires coming out of their chest and you’ll have to “maintain them” when not in use (which is most of the time, you’re only using these in an urgent situation). This means keeping them covered up and secured so they don’t get pulled out on accident. A lot of places will use an empty syringe to cover them and tape them together.
I once was taking care of a post-op CABG patient on the cardiac surgery floor. He was quite a few days post-op, but had multiple issues with dysrhythmias in the ICU, so they left the pacing wires in on him longer than they typically do. Normally, we would take the syringes in which the pacing wires are in and tuck them into the patient’s abdominal binder during ambulation so they aren’t dangling down and are at higher risk for getting pulled out. I was getting the patient out of the chair to go on a walk, and he heard and felt a POP in his chest. I was immediately terrified – I thought he just popped open his midsternal incision! It turns out; one of the pacing wires was stuck in the chair, but tucked where I couldn’t see it. And he basically pulled out his own pacing wire. I got him back in bed and the surgeon happened to be rounding at the nurse’s station. So I let him know. They were at the point where they were thinking about removing them, but had been cautiously leaving them in. He wasn’t upset, but I definitely learned a lesson: ALWAYS make sure your pacing wires are secure before moving the patient!
These will stay in place most likely their entire time in the ICU and will be removed when the patient is out on the cardiac floor, closer to discharge. Surgeons or advanced practice providers remove them at the bedside.
Should you need to use them, you'd plug them into a device that looks like what's pictured below.
Blood pressure monitoring and treatment is crucial in this post-operative period. If the blood pressure is too low, the grafts could collapse. If it’s too high, it could cause leaking and bleeding. You’ll most likely have the patient on a few drips and watching that blood pressure closely on the patient’s arterial line. These drips will be infusing through a central venous catheter (CVC) that you will also need to maintain.
Generally speaking, you’ll probably see a goal of keeping the MAP between 65-70 and the SBP between 110-130, which would be ideal. This may change depending on physician preference and the situation, but as you can tell, that’s a pretty tight parameter to maintain! One thing to consider with blood pressure management is that all patients are not alike and there isn’t one blanket parameter. The ultimate goal is end-organ perfusion. Therefore, if your patient has some co-morbities like renal issues or carotid stenosis, it would be reasonable to have a higher blood pressure parameter to maintain perfusion to those organs. There can be quite a bit of grey area with these parameters, as the unique needs of each patient are so dynamic.
Make sure your bedside monitor’s alarms are specific to your patient as well. Alarm fatigue is a very real and dangerous thing, so customize your alarms to your unique patient’s parameters to enable yourself to act accordingly and promptly.
Bottom line: know your parameters and stick to them!
Electrolytes and fluids are also monitored closely. Potassium is usually aggressively treated, which isn’t a surprise! Generally speaking, you’re looking to maintain it between 4-5 to proactively prevent the common post-operative complication of dysrhythmias. Your facility may have nurse-driven protocols in place for the frequency of the lab draws and potassium (and other electrolyte) replacement. These can be cumbersome to learn, but once you get familiarized with them they are pretty awesome and enable the nurse to work autonomously.
During the operation, patients are cooled. Once the patient comes up to the ICU post-operatively they need to be re-warmed. Rewarming cannot be done too quickly, as it can result in neurological injury. Follow your unit protocol closely!
Post-operative cardiac floor care
Once the patient heads out to the cardiac floor, they have been extubated and are stable. They most likely still have pacing wires and a chest tube or two. They will still have IV access, and theoretically should only have a CVC if they truly need it. Those should be discontinued as soon as medically appropriate. So, this means the patient is no longer on drips and not receiving any medications that cannot be given through a peripheral IV. They’ll have their midsternal incision and possibly others.
Instead of being assessed every 4 hours like in the ICU, these patients get a full head to toe assessment once a shift. Rather than stabilization, the goal shifts towards increasing mobility and discharge planning. Your facility may have them work closely with cardiac rehab, physical therapy, and occupational therapy, who will have some specific goals they must meet for discharge. Examples of these goals include walking a certain distance, walking a flight of stairs, showering, etc.
As the nurse, you want to encourage maximum effort with therapy services. You may need to time some pain medication with therapy to ensure they’re working to the best of their capabilities with them.
A big thing to monitor for is dysrhythmias. Approximately 40% of post-op cardiac surgery patients experience them. Keep in mind that the more they did in the OR, the higher the risk for these complication. So, if your patient had a CABG x1 the risk for afib with RVR is much lower than a patient who had a combo CABG/AVR/MVR. Keep this in mind that these combo patients are the most likely to flip and they really should be on a beta blocker unless there is a good reason not to.
Incision care and monitoring is another priority. They will have a large incision in the middle of their chest and preventing that from splitting open (dehiscence) is really important. Patients at highest risk for dehisence are those with the LIMA/RIMA used because blood supply to the sternum is decreased. Additional risk factors that can increase a patient's risk for dehiscence are obesity and/or larger breasts (simply more weight for the incision), diabetes, steroid use, DMARD use for RA, or those with limited extremity mobility.
They may have something called “sternal precautions” ordered. However, the optimization of this is continually evolving and heavily researched by the physical and occupational therapy realm. There is a sweet spot between doing too much and not doing enough, which is different for each patient. However, generally speaking, they don’t want the patient to be pulling/pushing too much with their arms. Make sure you’re aware of your facility’s protocols and therapy’s recommendation regarding this.
Monitor the incisions for increased drainage, redness, tenderness, and all of your typical signs of infection (like watching their WBC count and fever). The midsternal incision is one you really want to watch closely, as an infection there can be much more serious than one on their leg or arm incision due to its proximity to the heart and major organs. Follow your orders for dressing changes closely.
Pain management is also important. The degree to which patients experience pain on the cardiac floor varies greatly. If the patient still has a chest tube in place, they most likely will be experiencing more discomfort than if they have no lines. Generally speaking, when we’re looking towards discharge, the patient is typically only receiving oral acetaminophen or an acetaminophen/hydrocodone (Norco) oral combination every 4-6 hours.
Discharge planning and instructions
Most patients are going to go home with home health visits after this surgery. However, some may head to rehab or and extended care facility. The determination of this is mainly made by physical and/or occupational therapy’s recommendation combined with the surgeon's.
When they head to another facility, you’ll be working with case management to facilitate placement. Once this has been secured and the patient is safe to discharge, you’ll simply call report to that facility and get them on their way (whether it be via ambulance, medic, or a transportation service).
When discharging home, you’re going to provide them and their caregiver with some pretty detailed instructions. See the below video for an example of uncomplicated discharge instructions for a typical CABG patient going home.
Please note; this is an EXAMPLE and not actual prescribed discharge instructions. It is very general and not all-inclusive. Follow your orders and hospital policies when providing actual discharge instructions to real patients.