Section: CME Category: Diagnostic Testing

What Perioperative Testing Do I Really Need?

Jarrod Shapiro, DPM

Jarrod Shapiro, DPM discusses the importance of the history and physical when it comes to choosing which pre-operative tests to order. Dr Shapiro also discusses each of the available pre-operative tests, what they examine, and when they are indicated to order in the perioperative setting.

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Goals and Objectives
  1. Analyze the importance of the preoperative history and physical
  2. Formulate appropriate testing indications for perioperative management
  3. Examine the limitations of various preoperative tests
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    Release Date: 09/06/2018 Expiration Date: 12/31/2020

  • Author
  • Jarrod Shapiro, DPM

    Associate Professor, College of Podiatric Medicine
    Western University of Health Sciences, Pomona, CA
    Associate Editor PRESENT Podiatry Online

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    Jarrod Shapiro Dr. Shapiro has nothing to disclose

  • Lecture Transcript
  • TAPE STARTS – [00:00]


    Speaker: Without further due I would like to welcome back to the podium Dr. Shapiro who is going to talk about what perioperative testing do I really need to do. So give a welcome to Dr. Shapiro. Thank you.

    [Applause]

    Jared Shapiro: Dr. Hall that was really inspirational. Thank you and congratulations on such a fabulous job. So I had the unenviable job of giving an academic lecture after a really good one like that, so we are going, I guess, come back to earth little bit and talk about preoperative testing. So really going to talk about the H&P and some specific instances where you order various testing and you are going to think this is really obvious and easy and maybe it is to some of you, but in my experience, this is what is currently happening is not necessarily what we should always be doing. So here is the case to sort of spark your thinking. You have a 50-year-old, otherwise healthy male. He has no allergies and you are planning a first MP fusion. My question for you to think about is what preoperative labs or imaging or testing would you actually order for this patient? On the other hand, here is a different patient. This is another male but he is a diabetic. He is 65. He is having an emergent transmetatarsal amputation. He has got blood sugars of 200 and MI a year ago. He has a bunch of comorbidities. What labs would you order on this patient? So what's the point, why do pre-op H&P? For your residents, I guess the questions would be does it help with your logs? Yeah, it kind of get you 50 comprehensive H&P taken care of. You have nothing better to do. You are bored. You want to waste the patient's time, sure, why not. How about it's fun to watch him hyperventilate? That's always good. If you have that patient nobody really like so much and maybe you want to get at him a little bit, you can watch him hyperventilate.

    [02:03]

    No, not really. That's not what you are doing. What you are really doing is you are trying to sort of anticipate any medical issues that are going to come up in the perioperative period. So why do that? So you want to detect unsuspected abnormalities. Right? These are the things that are going to crop up without you realizing that they are going to happen. You want to establish medical risks and then you also want to have some medical legal protection. Right? It's not so good to do that bunionectomy and then have the patient die on the table. It's not exactly good for your malpractice insurance. So in the past, what we would order is just a large battery of pretty every test. You would order a CBC, a comprehensive metabolic panel and EKG, chest x-ray, urinalysis, maybe a couple of other things that you can think of and the idea was to screen for underlying diseases. So the problem is that method although catching a lot of things doesn’t actually end up with better outcomes. So the problem here is that 5% of patients, if you order one lab, are going to have some abnormal result. If you order 20 tests, think of comprehensive metabolic panel and a CBC for example, 64%, going in completely in a false positive way, are going to have a positive result that tells you nothing. And then in fact that many clinicians even up to 60% will ignore an abnormal lab result. So you can think about that for some of your pre-op patients, someone has a maybe a slightly low hemoglobin and you are like, okay, that's nothing or maybe their creatinine and BUN are little bit elevated and you think they are all just little dehydrated. That’s pretty much what we are kind of seeing.

    [04:00]

    So my suggestion to you will be to change that, so instead you order your labs, your imaging and other testing according to your history and physical and then known risk factors for that patient. So this is really the paradigm of kind of where things are going now when it comes to preoperative testing. So you order your labs, you order your imaging after you do your history and really good physical exam. This isn't you know just put the stethoscope on the chest kind of a thing. This is a real H&P. So here is another case for you. So you are about to do a bunionectomy on a 25-year-old otherwise healthy female. You are planning for MAC and local anesthesia. So what would you order on this one? So I will give you a second to think about it and you might think, oh, well maybe I need a pregnancy test and maybe I need a BUN and creatinine. I need all the labs and I need CBC, I need comprehensive metabolic panel. I got to check to make sure liver is okay. No, you don’t actually need to do any of that stuff. So let's talk about the healthy patient real quickly. So you want to decrease the risks of complications by really watching for certain things and many of these you will notice are going to be in the history and physical. Right? Their allergies, their surgical history. Are there coagulation disorders in the family? That one is relatively predictive of having a perioperative complication. What medications are they on? For me, medication has always been a thing. If ask somebody what kind of medical problems do you've? What do your doctors see you for? And they will give me a couple of things. They will skip hypertension because they think they don't have it because they are taking an antihypertensive medication. But then you look at the med list and you can see that they are taking antihypertensive, thyroid medication or something like that and that is really what's telling you what the things that are really a problem in this patient.

    [06:02]

    Have they had prior anesthetic complications? Of course, for somebody who is new to surgery that wouldn't have had any, but if there had been either in them or in their family, you can start to anticipate some problems. And then their social history, which includes all the regular things including pregnancy. So what about overall surgical risk? So for the elderly if they are under 65 years old, they have 1% mortality risk for an elective surgery. As they get older, it goes up to 5% and then 10% as they get older than 80. So those surgical risks are little bit more significant for the elderly patient. Overall, the operative mortality is one in 10,000. So if you do 10,000 surgeries in a period of time, you are statistically likely to have one of die in the perioperative period. That's not too bad if you think about it. One in 10,000 is okay. If I have one in 10,000 chance of my plane crashing tonight, I am probably still going to take the plane. So let's go over some sort of specifics. Should you order a chest x-ray? Overall, the evidence that we have for ordering chest x-rays in the perioperative period is relatively weak. But from what we have, we know that if you order one, you are going to get an abnormal result on this chest x-ray somewhere between 2.5% and 37% of the time. That's regardless of whether the patients have any symptoms or not. In studies that have been done, they have shown that it leads to a change in management at maximum 2.5% of the time. So it's not really giving you much information that you are going to use to do something with to help protect your patient. Going back, here we go.

    [08:00]

    So what should you do? You order a chest x-ray if there are signs or symptoms of active chest disease. So if the patient is telling you about some issue, they have asthma, they have some pulmonary disorder, something along those lines, then you might get the chest x-ray. You might get other testing as well. What about CBC? This is probably the most common test. Everybody just throw it in there. So CBC is easy whatever. Routine testing of this leads to management changes up to 2.7% of patients. That's pretty low. Can you imagine the last patient that you had that was undergoing a surgery who had some abnormal value on their CBC and you cancel their surgery because of it. I can. So don't order that routinely. Remember I am not saying don't order it, I am just saying don't order it routinely. I will order a CBC if I have a female patient who is menstruating and we are concerned about that. Maybe there is iron deficiency anemia, something like that. I want to kind of have an idea, then I would order that CBC for person like that. So if you expect significant blood loss, that's pretty obvious, right? Luckily most of our surgeries are in the low risk area on blood loss. If you have a patient who has limited preoperative primary care, then you may need to order more testing in that kind of case because you are really not sure what kind of medical conditions they really might have. They have a greater chance of having underlying medical problems. And then if you suspect anemia or polycythemia, then of course you want to order a CBC. So what about coag studies? I see this one really commonly in my area where people order a PT, a PTT and an INR on a patient who has no liver disease and isn't taking Coumadin. I am not sure why you would order an INR on somebody who is not taking Coumadin.

    [10:04]

    That's pretty much what it's for, so why bother with it? So testing has shown that one in 750 patients will benefit from coagulation testing. Not such a greater number if you are ordering coags. So low risk populations, you don't need to order coag. What you do is you want to ask about bleeding disorders, family history of bleeding disorder, any liver disease. If you have a patient you are concerned about malabsorption syndromes or malnutrition, then these tests would be useful and they are looking really for kind of liver issues as well. So what about labs, other labs, serum labs. So we are talking about your regular kind of comprehensive metabolic panel or BMP. So these same thing abnormalities rarely result in changes in management. So again, if you know they have an organ disease -- someone has chronic renal insufficiency, you are going to be ordering testing, right? That's pretty obvious. But in a patient who is otherwise healthy, you don't need to order it because it's not really going to be giving you any information that you really need to take care of this patient. If they have cancer, obviously that kind of patient is a much higher risk patient. You have to think about all the issues pertinent to that. Liver disease for metastases is something that you have to kind of double check. How about urinalysis? I like this picture. He is not really peeing. So it takes a second to see it, doesn't it? I will tell you. So a while back, I was going to be a kidney donor for somebody. I am not healthy enough for that. But I was going to try to be and they gave me -- they do a whole bunch of testing at the mayo clinic. They did a bunch of testing and I had a CT scan to look for all the anatomy in the renal area and stuff and they give you Lasix to flush out the contrast.

    [12:02]

    And I had it never had it before and I think I peed like this kid. It was unbelievable. I strongly suggest if your kidneys are good, try to stay away from Lasix as much as possible. So urinalysis is the same thing. There is noting that you get from a urinalysis that matters perioperatively that you are not going to get from a BUN and creatinine. Those are really the only things that really would matter and urinalysis is not the best way to do it. What about ECGs or EKGs depending on whether you are German or American, I guess. So this has been shown to be abnormal in up to almost 32% of patients. That's one in there is going to have some kind of abnormality and I don't know about you guys but when I ordered an EKG, everyone one of them says something about abnormal EKG and then it has some stuff on there that turns out to be essentially nothing. I have left ventricular hypertrophy, which is why I can't donate a kidney. But my cardiac function is 120% of my age group, which is 45. So my EKG shows something but my function is actually pretty good. So it's really not necessarily always telling you everything you need to know. We look at these tests as black and white, yes or no, the patient has disease or not and that's not necessarily what the reality is. So these perioperatively have weak values as far as predicting complications. So don't routinely order them on everybody but for those of a certain age, which is a phrase I learned that's meant to insult people who are starting to get older, you are of a certain age. So at 45, I am in that age group, so men greater than 40, women greater than 55, if there is a history of cardiac disease, you would obviously order it. And then in emergency situation, if this is all you could get and you are concerned, then of course the EKG is a quick thing to order.

    [14:07]

    Now what is important though is to determine cardiac risk. And when I send my patients to cardiologist, I don't request preoperative cardiac clearance. I request preoperative cardiac risk stratification and the reason I do this is we had a patient in our hospital who coded right after anesthesiologist gave Versed in the OR. We hadn't even started the procedure yet and the patient coded and then we ran a full code. Luckily, the patient survived but we hadn't done beforehand was really be aware of his cardiac risk, which was relatively high looking back on the patient when we kind of did our M&M report. So there are few different ways to look at cardiac risk. One is by the type of procedure that you are doing. So low risk is less than 1% chance of having complications and that's things like endoscopic procedures, eye surgery, those kinds of things. Medium risk includes general orthopedics, which is going to include us for the most part. And then you are going to have the high risk ones, which are really more vascular procedures or situations where you think is going to be a significant amount of fluid movement or blood loss. So just generally you can put patients into this sort of stratification. So then there is also the Duke Activity Scale, which you guys might have heard of METS or metabolic equivalence. And if you ask these patients sort of what they are capable of doing prior to their surgery, this helps to predict their risk of cardiac events during a surgery. So just from a simplistic sort of memorization standpoint, one MET would be performing activities of daily living.

    [16:01]

    Washing clothes, that kind of thing, walking around the house. If your patient can walk up a flight of steps, that's 4 METS and if they are kind of higher level athlete or they are doing strenuous activities that's considered 10. So anything greater than 4 to 6 is considered a higher risk and the cardiologist that we work with tend to use this to get a good gauge as to whether or not these patients are high risk from a cardiac standpoint and we all know cardiac is the main thing that we are looking at when we were talking about perioperative risk. So then there is relative cardiac risk index. So this is the old Goldman classification that you might have learned in school. They kind of updated it and what they looked at is first ischemic heart disease and you can ask you about things like if they have had a history of MI and those kinds of things. Do they have congestive heart failure? Do they have a history of stroke or TIAs? Are they a type 2 diabetic who is on insulin? The insulin is important, so it's not just regular diabetics. If they have renal insufficiency and if the surgery itself is considered high risk? Remember that's really the vascular ones. I mentally put my sort of larger procedures like if I am doing like TTC fusion or triple, something along those lines, I tend to sort of put that into the higher risk surgery in my mind. So what you do with this is you add them up and you get X number out of six of those. So 0 to 6 risk factors is 0.5% risk for major adverse cardiac event. That's what MACE stands for. Major adverse cardiac event. So 1 of 6 gives you a 1.3% risk, 2 of 6 is a 6.6% and 3 of 6 is 11%.

    [18:02]

    Now, those numbers might not sound terribly high at the beginning but remember that 11% risk of having a cardiac event during a surgery is actually considered pretty high. Even a cardiac patient undergoing really mild procedure would have a lower percent risk of this. So really anything above that 2 out of 6 level is starting to get into the higher risk and these are the patients that you would then want to refer to cardiology for stress testing or whatever you need to do before they have their elective surgery. Now obviously, for emergent surgery, you may not have that ability to adjust and have them see their cardiologist beforehand. I go into a fight recently with one of my anesthesiologist as I had a guy with necrotizing fasciitis and he wanted to get a cardiologist in because the EKG showed up with something that looked like had pericarditis. I am like, well, this guy is not going to make it. So we are going to go in now or else. So you can think about, do you want to do spinal anesthesia? Can you do this under local? Sometimes regional blocks are really good for this type of thing, but you want to consider that. So think about this case. You are taking a 56-year-old type 2 diabetic male for a tibtalocalc fusion. You planned this for about four hours. It's general anesthesia. He has an MI two years ago and hemoglobin A1c of 10. Now, if you go through that cardiac risk index, you would see that you can't answer specifically of the information that I gave you but this patient had a little bit higher risk. So the diabetic patient is a little different in that we know that they have significantly higher risk for complications associated with other disorders, right? All the vascular diseases, hypertension, dyslipidemia, obstructive sleep apnea, all of these, cardiac disease, these are significant.

    [20:05]

    We know that there is autonomic neuropathy, which will affect the cardiac function and they can have silent MIs. So they may not tell you that they have the history of MI. My suggestion based on this is to order these tests. So a CBC, you want to make sure to see if they have the anemia of chronic disease. Basic metabolic panel is going to check their renal function, their A1c, obviously, the TSH and an EKG. And then if you need to, you obviously will consider cardiac testing as necessary. So what about blood sugar and surgery? This one comes up quite often. When do I take my patient in for surgery? I have a diabetic patient with a wound. I want to do X procedure on them. When is it safe? For us, safe is not necessarily the perioperative part. That's all the rest of it, but also what are their risks of other complications related to their feet? So a whole bunch of studies here but TMAs have shown to have better overall healing if the A1c is less than 8. [indecipherable] [00:21:11] did a very large study that looked at, I think it was close to 2000 patients if I am remembering right. If the A1c was greater than 8, they had increased risk of skin and skin structure infections and then another sort of meta analysis by Jupiter and colleagues showed the same kind of things at A1c greater than 7.3. This Hofer study [phonetic], they found that for every 1% elevation above the normal, the odds of infection increased by almost two times. So that's not good. We definitely know that the higher it gets, the less chances you have of getting through this without issues. So really for me, I look at anything greater than A1c of 8 is sort of my threshold as either knowing I am going to have complications or trying to have the patient go back and adjust those.

    [22:09]

    I get much more stringent on patients if I am doing like a Charcot reconstruction. If their A1c is 8, I am not doing the surgery. If it gets down to 7, I am a little bit more willing to do it. I tend to see a lot less complications that way. So what about pulmonary disease? So again, same thing back to the same spiel I have been telling you for the last few minutes. And H&P is still your best way to determine pulmonary disease. So you order a chest x-ray if you need to, if they have a history of asthma. You can order pulmonary function testing. You can have them see a pulmonologist. If they have COPD, you definitely need pulmonary function testing and ABG. If they are smoker, I think nowadays you know some people will still take care of smoker surgically. I want to see the smoker really donate some effort into stopping smoking before I will electively take care of something. So for a bunion, I am not going to really want to do surgery on a smoker unless that person is legitimately showing me and then I am testing them later with nicotine levels and those kinds of things to determine if they are okay. Now, there is another one that I hadn't actually heard of until I started looking into the literature but there is this nice easy test, it's called cough test we all do it. So that's kind of good. So what you do ask your patient to take a deep breath and then cough. If they start to cough and continue coughing, then there is a high risk of having pulmonary complications during the perioperative period. That would be when you want to have them go and see their primary care doctor or their pulmonologist and have some further testing done.

    [24:04]

    What about the immune compromised? You really do have to focus this on the patient. We know that they have increased cardiac disease in patients with rheumatoid arthritis and in those patients, you definitely want to make sure they get the full blown kind of workup. We all know about getting x-rays unilateral c-spine to prevent complications associated with spinal axis deviations. So a neural flexion and extension as well as lateral c-spine will help you to see if t you have atlantoaxial subluxation. What about nothing by mouth? Everybody says n.p.o. after midnight. Right? It seems like everybody does this kind of everywhere it's universal. Really the ASA guidelines on this are a little different. So they are suggesting nothing my mouth for two hours for the majority of patients essentially healthy patients. Greater than six hours if you have had solid food. Kids are little different, so I am hopefully there aren't too many adults who are breastfeeding. So greater than four hours for infants and greater than six hours if the infant is taking formula. And then you want to increase your n.p.o. time for somebody who has signs of slow gastric emptying. So your diabetic with gastroparesis, those patients you might do that n.p.o. after midnight. I still have to fight with my anesthesia staff to go beyond at least eight hours. So here is a case from the beginning. So a 50-year-old male, no allergies, you are planning to do an MPJ arthrodesis. So my question would be at this point what would you order? For me, he is 50, so he gets an EKG.

    [26:00]

    In essence if he is otherwise totally healthy and EKG is normal, he doesn't really need anything else. This is probably going to be a case done under Mac MacLellan:, maybe general and for the most part, that's really all you are going to need. I know that sounds like a little minimalist. And if you are really concerned, a CBC and BMP, they are not terribly expensive, you're probably just are going to get normal results after that. So this one on the other hand is a bit different, right? Now, if it's emergent, you have limited ability to work up your patient. So in this one, he is probably going to be in the hospital. He will already have received a complete metabolic panel along with everything else. The A1c, that's all going to be there but if you are ordering the test, really you focus this on the fact that they are diabetic and that they have cardiac disease. What's really more important than ordering the test is making sure that the cardiac risk index is low enough and then having any kind of workup for that that you need. So in conclusion, don't order a battery of labs. It's not going to do any good and it's actually going to increase your medical legal risk. By the way, if you are getting an abnormal lab result and you don't do anything about it and there is a complication as a result of that, then you are on the hook. So if you get an abnormal result, then refer it and let somebody decide on their malpractice time whether or not the surgery should go. Do your orders based on H&P. You being a doctor and you are using your mind to come up with these diagnoses and treatments. And then my best suggestion is to determine your patient's cardiac risk index based on their METS and their revised cardiac risk index and hopefully you will never have any patients with any perioperative complications. And if that happens, then you are probably not a surgeon because it's going to happen. So on that note, thank you very much for your time today. Appreciate it.

    [Applause]


    TAPE ENDS - [28:20]