Latest / Behind The Knife: The Surgery Podcast / EPA Playbook: Small Bowel Obstruction
Transcript
- SBO EPA === [00:00:00] Welcome back to the EPA Playbook, our series, we explore the entrustable professional activities for general surgery residents. I'm Patrick Geoff, and today I'm joined by our BTK Surgical Education Fellows, Dr. Agnes Prem Kumar from Creighton, and Dr. Emma Burke from Baylor. And today's episode is focused on the management of small bowel obstruction, the classic, perhaps the most classic general surgery consult. Yeah, and to recap EPAs matter because they translate the abstract language of competencies into the real work you do every day. As a surgical resident, this EPA covers small bowel obstruction. Each EPA defines a professional activity. You must eventually be trusted to perform independently. EPAs may also make feedback more meaningful by increasing objectivity and providing more data points across time, specialty case type, and case complexity. When you demonstrate consistent entrustment on EPAs, it accelerates your progression toward independent operating and decision making, and that's why we've created this [00:01:00] series. It's the perfect way for junior residents to dominate EPAs. Great. Let's start with the case. So Agnes, you are the senior resident on call. The ED wants to get your input on a 68-year-old man, Mr. Lewis, who presents with crampy abdominal pain, distension and vomiting for 12 hours. He said three prior abdominal operations, including sigmoid colectomy, and he's waiting on a CT scan, but they wanted to get you involved early. So what's your first step? So I'd start with a focus, history, the timing, and the characterization of the pain. When was his last bowel movement? Has he passed neo flatus? What's going on with his nausea and vomiting and any prior abdominal surgeries? His symptoms based on the page are pretty vague, so on my differential, I have small bowel obstruction, gastroenteritis, diverticulitis, and inflammatory bowel disease. A small bowel obstruction specifically refers to a mechanical obstruction of the small intestine that leads to proximal bowel dilation. As fluid air and intestinal contents get backed up, so ischemia results from a physical compression of the [00:02:00] vasculature and dilation causing intestinal wall pressure to exceed the capillary. I am sure we all wanna CT scan without even seeing this patient, but it's important to remember that obstruction is always a clinical diagnosis. That's why seeing the patient to clarify symptoms is so important. Onset of symptoms can be a useful thing to ask about. For a lot of patients with an SBO, they can pinpoint exactly when their symptoms began. I also like to ask about red flags such as fevers or peritoneal signs that may suggest ischemia or strangulation of bowel, and I'd review his medications, anticoagulation, especially comorbidities, and confirm his surgical history to wrap up our discussion. Good. Let's talk about the physical exam. What are you looking for? I'm looking for abdominal distension, surgical scars, tenderness, and importantly, whether there's guarding or rigidity to suggest peritonitis. Adhesions from a prior surgery are the most common cause of an SBO, which is why understanding a patient's surgical history is so important. If the patient has never had surgery before and [00:03:00] presents with an SBO, I'm concerned for other pathologies like a congenital band malignancy or inflammatory bowel disease. And don't forget to check for hernia. Small bowel obstructions caused by hernia need operative intervention, and these patients are not eligible for conservative management since they have a high risk of strangulation in the scenario. Yeah, it's important to note that the vast majority of SBOs are for mechanical obstruction, but up to 20%. Will occur in patients who've never had surgery before. So Mr. Lewis is distended and tender, but does not have signs of peritonitis. His pain started 12 hours ago and is associated with nausea and vomiting. His last bowel movement was yesterday morning and he hasn't passed gas since. The CT scan is done right after you see him, and it shows multiple loops of small bowel with a single transition point, and no free air. Lactate is normal. Emma, what's your diagnosis? His history and exam. Tell me all I need to know that Mr. Lewis has a small bowel obstruction. However, the CT scan is reassuring in that he doesn't need an urgent operation. Mesenteric [00:04:00] edema and lack of small bowel feces on imaging are risk factors for patient needing operative intervention. Positive small bowel FE C sign is the present of fent matter and gas bubbles in the small bowel. When it's present, it tells us that the obstruction has developed slowly with enough time for water to be reabsorbed in the small intestine. Other things to look out for are thickened bowel wall, a target sign, pneumatosis in test analysis, or portal venous gas. These are all concerning for bowel strangulation. Yeah, and that's a really great point. Any concerning findings on CT scan, you really need to think about operating that patient sooner rather than later. The CT scan can also be helpful to evaluate for closed loop obstructions and help clarify anatomy such as patients with a history of bariatric surgery. Patients with a history of bariatric surgery are at risk for an internal hernia, which can lead to what we call a closed loop. SBO Closed loop obstructions are associated with a swirl sign on imaging, which reflects a twisting of the bowel around a fixed point [00:05:00] great. So we got a clean diagnosis here, right, Mr. Lewis' history. Physical exam and imaging findings are often consistent with small bowel obstruction agonist. Walk me through your initial management now that we have a good diagnosis. So first is resuscitate. These patients are often volume down from their vomiting and nausea. So let's start with some IV fluids and correct their electrolytes. I plays a nasal gastric tube for decompression and keep that patient NPO. I would wanna get a big NG tube, at least a 16 French, to make sure that gastric and small bowel contents or able to be sucked up, a tiny 12 French NG tube is gonna get clogged and it's not gonna provide much benefit. And I know we all wanna cause the least amount of patient discomfort by putting in a small tube, but if it gets clogged and then you have to replace it to a larger tube, that just means more misery. So it's better to do it right for the first time. And we have a great series of videos on NG tube insertion and management in our bedside procedures, video playlist, and we'll link those in the show notes as well. Yeah, I gotta say that bedside procedures playlist is pretty robust and growing. And [00:06:00] so again, for if you're listening to this podcast and finding it particularly useful, you should check out that video playlist. There's lots of really, you know, useful, practical things in there about how you do procedures at the bedside. Alright, so you've, notified the attending early as these patients need to be watched closely. You've described your plan in which they're in agreement with. Now. How do you decide whether to manage this patient non-operatively or operatively? So it's good to know that most obstructions resolve non-operatively. So if there are no peritoneal signs and the vitals are stable, we can trial conservative management. That's right about 80%. Sometimes depending on what study you're looking at, even a little bit higher of, a small bowel obstruction will resolve without surgery. So that's a good amount. You know, the vast majority of folks with decompression , typically resolve, right? But red flags like fever, tachycardia, and elevated lactate. Or imaging findings of pneumatosis or free air, all push it towards the or subtle CT scan findings are [00:07:00] bowel and mesentery, wall thickening or reactive fluid. They can also influence your decision to pursue operative management. And importantly, patients with incarcerated or strangulated hernias are not eligible for non-operative management since they have a high risk of ischemia and bowel necros. So like we mentioned, most SBOs resolve with conservative management, and based on Mr. Lewis' exam and ct, he would be eligible for a trial of non-operative management with a Gastrografin challenge. Yes, the Gastro grafting challenge, this is such a useful tool, so it's really important that you understand this and know it well. And it, has really been a change in terms of how we manage these patients. Over the past couple decades, really, as the gastro grafting challenge has become really a fixture in, the acute care surgery world in terms of managing SBO. So let's talk more about it. What is a gastro grafting challenge? Gastrografin is a hyperosmotic contrast that has diagnostic and therapeutic purposes. We can track its transit through the small bowel in colon over time on [00:08:00] x-ray in a more dynamic study than a one-time CT scan. Because it's hyper asthmatic, it can also reduce bowel wall edema, which can help resolve an existing obstruction. There's a large multicenter trial by Z's. Gal from 2017 that showed use of GASTROGRAFIN in patients with adhesive SBO reduced the rate of operative intervention and length of stay compared to those patients who just underwent NG tube decompression alone in their protocol. Patients were decompressed with an NG tube for two hours. Then they were given a mixture of gastro graft and water through their NG tube. They then obtained abdominal x-rays eight hours later to look at the contrast in the colon, which was considered a pass having a bowel movement. By the time of follow-up, x-ray also counted as a pass. It's important to note that this study excluded patients with a hernia or history of cancer or recent abdominal operation. So all in all, about two thirds of the patients in the Gastrografin group passed and only 20% needed surgery compared to 44% of patients in the non [00:09:00] gastro group. Yeah, I think it's important to note that different institutions will have different protocols. There are a few key points to the protocols. Number one is that you start by adequately decompressing the patient. That could be two hours, it could be six hours. More importantly, it is how's the patient looking, so if they're still massively descended and not well, you wanna hold off on your gastro graft and challenge until they're safely decompressed. The other consideration. Is age as well. So if a patient has a really high risk of aspiration, now, God forbid they have an NG tube in you, you do your challenge and they throw up. A healthy 40-year-old individual will probably be just fine. If it's a unhealthy 80 or 90-year-old individual, they could get, an aspiration event that could lead to PEA or s and they die, which is terrible. We don't want them. So let's make absolutely make sure that patient's fully, you know, decompressed and on the right track. And then in terms of the sequence and the timing of x-rays, that's been explored. There is some newer data that's just, maybe your first x-ray occurring at six hours is a good, a time window to. Catch more folks, who may be [00:10:00] passing so they can move through, that sequence of events in which we advance their diet and get outta the hospital. Again, the classic is starting at eight hours and then 24 hours. Yeah, and something else that we do sometimes is we'll get an x-ray not long after we've put the contrast down the NG tube to make sure it doesn't get hooked back up to suction and sucked right out. So some other protocols, like we mentioned, KUB, is at 24 and 48 hours and if there's no improvement by that 48 hour mark, it's pretty likely that the patient will need an operation. Regardless, like we mentioned, of the protocol you use, it's important to ensure the patient is decompressed. You know, the NG tube stents open that lower esophageal sphincter, which again, in patients at high risk of aspiration, like the elderly can be a very dangerous situation. Right, right. Okay, so let's say Mr. Lewis gets his gastrografin and there's no contrast in the colon at eight hours. And at 24 hours and we've waited, onto that 48 hour mark. I would say that a lot of institutions will call it a 24. But certainly let's say for this patient, [00:11:00] just to be clear, we're up to 48 hours and nothing's changed. He has persistent pain and high NG tube output. You're gonna take him to the or. So Agnes, how do you counsel this patient in terms of, the preoperative planning, what you're gonna do in the operating room? Yeah. In cases like these, I think it's best to discuss a few possible outcomes. I like to use the best case, worst case framework. So the best case for Mr. Lewis is that we do a minimally invasive license of adhesions. We see the band that's causing his obstruction, and we can fix the problem rather quickly without a big open surgery. The worst case would be the need for conversion to an open procedure with some resection of non-viable bowel and a possible ostomy. Yeah. So speaking of minimally invasive surgery, how do we decide which SVO patients can, safely proceed with an MIS operation? So the big concern in an SBO is that the bowel will be too distended to establish adequate pneumoperitoneum, making laparoscopic or even robotic modalities unsafe. However, in patients who are adequately decompressed and those [00:12:00] without extensive adhesions, laparoscopy can be used. It's important to counsel patients that just because you start laparoscopically does not mean that they won't need an open surgery. The conversion rate is as high as about 30% in SBO. 30% sounds a little bit low to me. You know, if it's a mess in that belly, you're gonna wanna, open and, safely, run that bowel and resolve any kind of, obstructive processes. But, if you can safely get in, it's a great idea to try minimally invasive as you can hopefully save the patient from big laparotomy. So in this case, Mr. Lewis is a good candidate, for diagnostic laparoscopy. Agnes, how do you safely gain access to the abdomen? Unlike other procedures where there's a standardized port placement when you're operating for an SBO, we need to have more flexibility in where our ports go. We always wanna position the ports away from existing surgical scars and away from any distended loops of bowel that you might have seen on imaging. This will help decrease our enterotomy risk on entry and also provide adequate working [00:13:00] space to take down any existing adhesions. Then we'll proceed to running the bell. To run the bowel, we wanna start from the decompressed bowel and run approximately towards the obstruction. I like to find the appendix or the terminal ileum to start. You'll wanna run the bowel methodically inspecting for any signs of malperfusion. And once you encounter your obstruction point, what we find dictates our intervention for an adhesive band, we can use electrocautery to divide the band For an internal hernia, it's important that we reduce the bowel and close the mesenteric defect. But regardless of what intervention you need, it's important to assess and then reassess the bowels viability. If the bowel still appears dusky and non-viable after your lysis of adhesions or internal hernia reduction, you need to consider a resection Depending on surgeon. In preference, you may wanna convert to open if resection and anastomosis is necessary. While this might feel like the end of the case, don't forget to finish running the small bowel back to the ligament of trites. You don't wanna miss any other pathology [00:14:00] or an enterotomy that would require a take back. Yeah, within reason, you wanna make sure that you're really doing a good job of seeing all the bowel and making sure everything's cleared up. Now we are not gonna cover it in detail today, but when it comes to malignant obstructions. That's a whole nother beast. Okay, so today we're focusing on, benign, pathology leading to a small bowel obstruction. We'll let that be. Just know that if you're gonna be seeing a patient for a consult that has an SVO and it's actually secondary to cancer, that you may be on a different track in terms of how you plan, surgery or not diversion, et cetera, palliation, all those things. So in this case, it went well. You lysed, adhesions and resected a short necrotic segment, and you performed a primary anastomosis. The patient's now in the pacu, what are your key post-op priorities? So we wanna monitor for hemodynamic stability, urine output, and any signs of sepsis or ongoing obstruction. We wanna keep that NG tube patent until the patient passes gas or has return of bowel function. And as [00:15:00] with most of our patients, pain control should be multimodal. You wanna limit opioids to reduce an ileus risk early ambulation. Incentives, spirometry and DVT prophylaxis are all crucial. Yeah, the bugaboo here is really your anastomosis, right? Ensuring that heals. This is a relatively healthy patient. We would expect that to heal well, especially a small bowel anastomosis, but we gotta keep our eye out for anastomotic leak that's most common, four to seven days or so postoperatively. But really what's common and not a complication, per se, is an ileus, right? This patient had a bowel obstruction before we started surgery. They had abnormal dilated bowel, and then we manipulate the bowel surgery, give anesthetic medications like the narcotics as well. The expectation is that they have an alias, and so we're gonna watch that. Most aliases last somewhere between three to five days, sometimes even up to seven days. So I think it's really important that you counsel your patients on this. Because a lot of times surgery will go well, are we doing a nice job? The patient's gonna recover well. And yet they're sitting there. We tell 'em, [00:16:00] Hey, you did great. Surgery went well, and your twiddling your thumbs, waiting for their bowel function to return. I think it's a great idea in advance of surgery to say, Hey, this is a normal thing. Your bowels are angry, they're lazy right now. They're gonna wake back up and start working again. So when it comes to diet advancement, Agnes, how do you think about that and what do we need to do? Once bowel function returns, we can start by first removing the NG tube, starting off with some clear liquids, and then advancing as tolerated. Early feeding can be considered if there's no evidence of an ileus. And remember, like we learned back in medical school on plain film, ileus has a uniform generalized dilation of the large and small bowel, versus an SBO. The distension is proximal to the obstruction and the distal large bowel and small bowel are decompressed. So be sure you can differentiate between both of these diagnoses since the presentation is largely similar. Yeah, if you did a good job in surgery, recurrent SBO is rare, but certainly can occur and you manage a early recurrent SBO differently than you do a late SBO [00:17:00] months or years later. Alright, now we're gonna go on a limb here, and not explain why or how, but just for the sake of discussion, because this is an EPA discussion, let's say Mr. Lewis got a diverting. Loop ileostomy. This is a good opportunity to talk about ostomies 'cause management is, important, and, and they can be problematic. So Emma, what do we need to think about in a patient with a new ileostomy. For all of our new ileostomy patients, regardless of the reason they're given an ileostomy fluid balance is so, so critical while they're inpatient. This can be easier to manage with scheduled IV fluid boluses determined by the ostomy output for the day, and then trending electrolytes patient education before discharge about urine monitoring. Ostomy output, and fluid intake is key. Some patients are able to go home with a midline and get outpatient IV fluids in the acute phase. However, that's not always an option. And if you have a patient who has a persistently high ostomy output, you can add [00:18:00] fiber to bulk the stool. And if that doesn't decrease the output enough, you can do the next level, which is uprate Imodium to minimize fluid loss. And in extreme cases, you can add a tincture of opium. I just think it's important to get your ostomy nurses involved early. They're just such a wealth of information and knowledge for patients about how to take care of their ostomy, what changes they need to do and what supplies they should have on hand. So we have a few videos under our bedside procedure section that were made with an ostomy nurse, be sure to check those out if you haven't seen them before. Yeah. Ostomy education is critical, especially small bowel or ill or ileostomy education. You know, in general, these patients are gonna have an ilias. Right, so nothing's gonna be coming out of it, and then they're gonna dump. Usually we wanna let that happen for at least a day or two, kind of let things open up and move, support 'em with fluids, electrolytes, et cetera. And typically, most patients, if they have a new small bowel ostomy. Their bodies haven't smartened up to that yet. And output in is in general gonna be higher than you want it to be. That's [00:19:00] thin, watery fluid with significant electrolyte loss. So we have to be very cognizant about how much is coming out. In general for an adult, we're looking at in general, less than one to 1.5 liters per day. And so to get there, most patients will require some degree of an antimotility agent. The most common and safe is Imodium. You can start by titrating that up, in a, staged fashion. If you need to go beyond the highest dose of Imodium, we typically add LA modal. And then you, had mentioned also, the use of Balkan agents and fiber agents, but the workhorse is really. Imodium and this is one of the highest causes of readmission following I ostomy. Ation is dehydration, acute kidney injury, electrolyte imbalance, et cetera, from patients having too much losses without enough replacements. And so that education is so critically important. And of course, Agnes, you mentioned the importance of the ostomy team. I mean, this is a big deal. If a patient gets an ostomy and you have bowel on your side, a stool coming out into a bag. And I don't know [00:20:00] about you, but every institution I've been at, the ostomy team, they're incredible. The wound care ostomy teams are like the most incredible individuals in that institution. And, them being able to spend time on patients and their family talking about what an ostomy is, you know, how you manage it. The ins and outs of bagging and care, et cetera, is so important for the patient and their family to be comfortable. Ideally that process happens. Before surgery. Again, we'd mentioned we kind of threw this in because it's part of the EPA, but ideally you have that ostomy consult in advance. The patient knows what they're getting into about a possible ostomy, and ideally that it's marked, in the city position, standing position, et cetera. So on occasion we will sometimes see patients who return with recurrent, oftentimes partial, or although this is not a true medical term, low grade SBOs in the sense that they resolve. Without surgery. They come in, they're bloated, distended, you put an NG tube in 24 hours later, they feel great, or they pass their gastro graft and challenge over and over again. It's important that these patients, get seen in [00:21:00] clinic to talk about an elective, possibly elective lysis of adhesions. Ideally an MIS approach to that. So don't forget about those patients and let. We don't want them coming back to the ED over and over again. So, SBO there, there's a lot to talk about, even more than what we covered, but I think we did a good job of covering the basis of what's in the A-B-S-E-P-A. So for today's episode, go forth and dominate small bowel obstructions. Thank you for listening. This is just one episode in a series entitled the EPA Playbook, where we delve into each of the EPAs that are outlined by the American Board of Surgery. You can find more information about the EPA descriptions and the specific competencies for each topic on the A BS website. Hope you join us with an next episode and as always, dominate the day.