24 MIS - Final Edit

Behind the Knife Ab Site Review. Today, we're going to cover principles of minimally invasive surgery and endoscopy. So fair warning, this can be a little bit of a dry information, but there's always a handful of questions on this stuff. So it's definitely worth spending a few minutes on. So John, let's just dive right into it.

So a lot of it has to do with energy and surgery and the safe use of energy and surgery. So when we look at it at a cellular level, what is happening in electrosurgery at an intracellular level in the patient? So radiofrequency alternating current raises the tissue temperature as electromagnetic energy is converted intracellularly into kinetic energy.

Followed by thermal energy to achieve coagulation or cutting. So what's the difference between, you know, we always just set it to cut or coag. I feel like very few of us actually understand. It's getting better with that, with that FUSE curriculum that's required now in residency. But what's the difference between cut and coagulation?

So cut, this is a

favorite pimp question of mine in the operating room too. So cut is continuous low voltage energy. Where coagulation is high voltage energy for a low amount of time. Yeah, so it's actually only like 5 or 6 percent of the duty cycle of coagulation is, is, is on, but so it's a very high voltage for, for a low amount of time.

Okay, so John, we're, we're in the OR, we're going to use energy. We use monopolar energy all the time. And we have to put that dispersive electrode, the boby pad so where should that not be placed? So it shouldn't be placed, placed on bony provinces, hairy areas, scar tissue. Pressure area or points areas with skin discoloration or previous injury.

It should also be put in place on limbs with circulatory compromise. Also, it should be placed near metal implants, prosthesis any areas adjacent to leads or electrodes. And obviously, if there's jewelry present, it should not be near there. Okay. Additionally, you should never cut the dispersive pad, right, to a smaller size.

Never cut it. Okay. Okay. But

one thing that's frequently tested and comes up is patients with implanted cardiac devices. And so what steps should be taken to minimize the risk of energy injury to those patients with implanted cardiac devices? Yeah. So the dispersive electrode should be placed at the energy vector from the energy instrument avoids the cardiac device on its pathway to the heart.

So it shouldn't be placed between the cardiac device and the heart. Yeah. And then we also have the option of using things like bipolar or ultrasonic energy, which would of course would reduce the risk of, of in inadvertent ICD activation or damage, and avoid draping the cord near the ICD on its pathway to the heart.

Okay, so let's move into some high yield MIS pearls. So CO two pneumoperitoneum. What are its physiologic effects on the patient? Let's start with what are its cardiac effects? So it increase, CO2, Pneuma peritoneum will increase

central venous pressure, which then decreases your venous return and leading to decrease cardiac output.

It would also increase your systemic vascular resistance leading to increased blood pressure or map increases your heart rate increases your pulmonary artery pressure. And it decreases your organ perfusion to this plankton fascial compression. Great. So decreases cardiac output, increases MAP at heart rate, increases pulmonary arterial pressure and decreases organ perfusion.

Okay. So what about some pulmonary effects of pneumoperitoneum? So, it will increase your mean airway pressure increase peak inspiratory pressure decrease your functional residual capacity due to the elevation of the diaphragm during pneumoperitoneum, and it will increase your end tidal CO2.

Okay, perfect. Renal? You get decreased renal blood flow which then leads to decreased urine output. It also increased renin and ADH production due to that decreased blood flow. Okay.

And then with regard to your acid base, so if you're increasing your CO2, you're going to drop your pH. So all these things kind of make sense if you think about it.

You know, CO2, nomaperitoneum, you're raising the pressure. If you think about the physiologic sequela of doing that, these all make sense, but it's important to run through them because these can get you easy, easy, easy points on the exam. So at what intra abdominal pressure can patients start to develop cardiopulmonary dysfunction?

So anything greater than 20 millimeters of mercury normal is 10 to 15. Okay. Yeah. So we don't want to, we definitely don't want to turn our pressure up to that. Usually we're operating at 15 millimeters of mercury. Sometimes we'll have to lower that in patients who can tolerate it very well. So, absolutely.

What's the vagal nerve response and to insufflation and what can happen? Yeah, this is something you always look out for any time you initiate pneumoperitoneum. But extreme bradycardia. And you usually get it upon the first time you place the pneumoperitoneum in, or you start to insufflate.

So the treatment for this is that you just immediately desufflate the abdomen.

If it's persistent bradycardia, you want to consider atropine or glycopyrrolate. If there's no improvement with the desufflation, and that's the way it's gonna show up on the test, is you're gonna be performing a minimally invasive procedure. You're gonna insufflate the abdomen and the patient's heart rate is going to, is gonna drop precipitously.

And the question's gonna be, what's your next step? And your next step is desufflate the abdomen. Alright, so let's move on to endoscopy. So there's a lot of questions that are showing up on endoscopy and, and it's becoming more common. So let's start with an EGD. So what patients. should be given antibiotics prior to an EGD.

So this is patient specific. The things you want to look out for in your question stems are immunocompromised patients should all get them any cirrhotic patients patients with advanced hematologic malignancies, and also want to consider the procedure that they're undergoing. So we'd give preoperative antibiotics for PEG placements variceal bleeding control ERCP

for cholangitis or if you need to perform it for biliary drainage.

And obviously if endoscopic ultrasound. With FNA, a pancreatic cyst, we give antibiotics. Yeah, so your routine EGDs, I mean, we don't typically give antibiotics, but just be aware it's patient specific, procedure specific. There are some instances where you'd want to give prophylactic antibiotics. So let's say you're performing an EGD, and, you know, when visualizing the ampulla of Otter on endoscopy, what positions are the biliary duct and the pancreatic duct located within the duct?

The ampulla of Vader is in the duodenum, approximately 10 centimeters distal from the pylorus. Within the ampulla, the pancreatic duct is located at the one o'clock position and the biliary duct is at the 11 o'clock position. Right. Okay. Yeah. Biliary duct 11 o'clock. The pancreatic duct at one o'clock.

Okay. So can you describe the two categories of caustic agents that can lead to an esophageal injury when ingested and what is specific about each one? Yeah. So you have your alkali injuries

and your acid injuries. Your alkali injuries will lead to liquefactive necrosis that extends very rapidly through the esophageal mucosa.

So some examples of some agents for this would be ammonia, lye, and sodium hydroxide. Regarding acid injury you get superficial coagulation necrosis and that's associated with thrombosis of mucosal blood vessels and it develops an eschar. So if you had to choose one, if you you either had to have an acid.

Caustic injury or alkalized. So you, it's the coagulation necrosis versus liquefacted necrosis, which is worse. No, definitely the alkali injury or liquefacted necrosis is worse. Great. Absolutely. Okay. So let's talk a little bit about endoscopy and foreign body ingestion. So what are the regions along the esophagus that are physiologically narrower and therefore it can be problems with foreign body impactions.

So the three spots are the upper esophageal sphincter the crossover of the aorta and the lower esophageal

sphincter. Some other possible areas include the site of a congenital malformation or prior surgery sites. Okay. So some foreign body ingestions are more emergent or urgent than others. So what are some examples of foreign body ingestion that will require an emergent endoscopy?

So, in the emerging category, if you see these pop up would be if you have a complete esophageal obstruction or you can't really handle secretions is where that would come up. Any button batteries or obviously sharp objects that are lodged within the esophagus. Yeah, great. So, sharp objects, those disc batteries that kids like to swallow, those are emergencies.

And, like you say, if you have a complete impaction, a complete esophageal obstruction. Okay, how about some indications, or what are some foreign body ingestions that would require an ur not emergent, but urgent endoscopy? Yeah, we want to perform these within 24 hours. So, non sharp object that's lodged within the esophagus.

If you have non obstructing food impacted in the

esophagus magnets sharp objects in the stomach or duo or objects greater than five centimeters in length in the stomach or duo. Yeah, I think for test taking the most important things are recognizing those, those needs for an emergent endoscopy.

So again, complete obstruction batteries, this batteries or sharp objects in the esophagus need emergent endoscopy. So John so how, what size of objects are we, do we get worried that may fail to advance through the pylorus? Yeah. If there's anything greater or equal to two centimeters, They have a pretty high chance of not passing through.

Okay, great. Yeah, two centimeters. Anything bigger than that you worry about it passing through the pylorus. Okay. So moving on to lower GI endoscopy pearls. So something that is occasionally asked is what are the measures of high quality colonoscopies? You know, maybe they'll give you a list of things and say, you know, which of these is, is, is a measure of a high quality colonoscopy.

So what are those quality metrics? The big ones

are if the cecum has been intubated greater than 90 percent of all cases. If you have an average withdrawal time greater than six minutes in colonoscopies this is in patients with normal results or with intact anatomy. Your perforation rate should not exceed one in a thousand screening colonoscopies and, and in one in 500 colonoscopies overall.

Your incidence of post polypectomy bleeding should be less than 1%. And then if you do have post polypectomy bleeding. It's managed non operatively in greater than 90 percent of cases. Yeah, so the big ones there again that people like to ask are that your intubation rates are greater than 90 percent and that withdrawal time is greater than six minutes in colonoscopies.

Those are really your highest yield quality metrics when it comes to colonoscopies. So what about another frequently tested, frequently asked thing is post polypectomy syndrome. So, what is a post polypectomy syndrome? When does that occur? This occurs after a full thickness thermal injury to the colonic wall after polypectomy.

This causes localized inflammation and peritoneal irritation without actual perforation. And how do patients present? Patients will typically feel fine the day of procedure but then the next day they present with fever and localized pain. However, the imaging studies will not reveal any perforation.

Yeah. So these are patients that come in the next day with fever maybe even have a leukocytosis localized pain. And a key there is that they don't have things like free air on their on their imaging studies. So, what about management? You can manage a majority of these patients with close observation, sero abdominal exams.

bowel rest, some IV fluids, and antibiotics. Now sometimes they'll try to trick you and give you a patient that you're thinking post polypectomy syndrome, and then they have a bunch of free air on their imaging. And so those are the patients that you need to operate on and not manage post operatively. So be sure to make that distinction.

They like to ask that, and they like to make it a little bit tricky, so be familiar with that. And finally, let's cover some high yield

bronchoscopy. So, John, airway irritation during bronchoscopy can lead to bronchospasms pretty commonly, so how should this be treated? So you want to use a beta 2 agonist such as the most common one being albuterol.

Okay, so albuterol for, for bronchial spasms during bronchoscopy. So when let's say we're getting a BAL so when interpreting this quantitative BL, what is the diagnostic threshold to treat for pneumonia? Yeah. So you want to look for over 100, 000 colony forming units per milliliter. Okay. So something that's seen infrequently, but to be aware of is peanut aspirations and they're a little bit unique.

So, what's special about peanut aspirations and why is it so important to place these patients under observation? Yeah. So when the peanuts break down and release a peanut oil this is a very strong irritant and can cause an intense pneumonitis. Okay. I can honestly say I haven't seen that one before, but maybe this year.

Yeah, maybe. I've never seen it, but it's

good to know that you can get that intense pneumonitis after a peanut. So everybody be careful out there with your peanuts. Okay, let's wrap up some quick hits. Okay, John, what three quote unquote ingredients are needed for a potential OR fire? That'd be your ignition source fuel, and an oxidizer.

Right. Ignition source, fuel, and oxidizer. And we have all those things in the OR, right? We have our monopolar energy. Our fuel is usually our chloroprep. That's why it's important to have that drying time and your oxidizer. So especially, you know, patients are on face masks oxygen. Okay, next. So bipolar energy can be used to safely seal and achieve hemostasis in blood vessels of up to what size?

Yeah, I've actually seen this before. It's up to seven millimeters in diameter. Yeah, so bipolar energy seven millimeters in diameter Okay, so let's say you're in the OR and you notice a sudden rise in the end tidal co2 followed by a drop and Then the patient gets hypotensive. So what are you worried about?

What happened?

And how do you manage this? If you're worried about a co2 embolus the treatment for this has placed the patient in Trendelenburg position also placement left lateral decubitus position an attempt to aspirate the CO2 air embolus through a central line. Okay, so a patient presents with mild tachycardia and tachypnea after an upper endoscopic procedure.

On physical exam, you note subtle crepitus of the neck. So, what's your next step in management? Yeah, here you want to perform a gastrograph and esophagram. While barium is superior for demonstrating perforations, barium in the chest cavity can cause mediastinitis or pleuritis. So you wanna avoid it?

Good? Yeah. So your concern would be for perforation with the, with the crepitus in the neck after that procedure. So yeah. Gastro graft and water soluble esophagus. Okay. So when examining a patient suspected of ingestion of either a caustic agent or a foreign body, what physical exam findings should prompt endotracheal intubation?

Yeah, so the things you wanna look out for, dyspnea,

drooling, strider and or hoarseness. These are all caused by severe oropharyngeal or glottic edema. Great. Okay. So that, that wraps up our high yield review for minimally invasive surgery endoscopy. Again, you know, not meant to be comprehensive, but hopefully that'll get you a few points.

It is high yield and worth spending just a couple minutes on. So thank you for joining us.