VivaCast 15 – Clinical Case: IV Drug User with an infected PsuedoAneurysm

[00:01 – 00:28] Introduction

James: Hello, and welcome to Gas, Gas, Gas, the podcast that covers the FRCA primary exam. We’re going to fit into your day and give you as much of your life back as you could possibly imagine. I’m here to make your studying easier. Listen to us on your commute, in the gym, in the shower, or when you’re ironing your scrubs. Expect facts, concepts, model answers, and the odd tangent. Check out the show notes for all the detail, and remember to follow the show so that you never miss an episode. Let’s get on with it.

[00:28 – 01:34] Case Presentation

Well, Tom, it’s even later in the evening, and you’ve actually volunteered because you’re just an all-round good chap to be vivered yet again as a clinical station. It’s going to be 15 minutes. Technically, you would have a bit of reading time at the start to mosey and think, so we’ll offer that up at least so you can have some thinking off track. Are you ready for action?

Tom: Yeah.

James: Okay, lovely. So, you are on call for general emergency theatres, and the vascular SHO on call has booked an intravenous drug user who has a pseudoaneurysm, and they think there’s a bit of infection around it. There might be a needle in his groin as well. He tells you that he’s a heavy smoker, he has been injecting drugs recently, and that he was on the ward a week ago, but he absconded. Could you just summarise what I’ve told you, and let me know about what you think the problems might be with this encounter?

[01:34 – 04:04] Initial Assessment and Approach

Tom: So, you told me that there’s a vascular surgeon wanting to book a case for a known IV drug user for a potential pseudoaneurysm who’s a history of heavy smoking. They want to operate urgently, and there’s also potential for infection around the pseudoaneurysm.

James: Yeah, lovely.

Tom: So, I’ll tell you how I’d approach it. First of all, I want to go and see the patient on the ward. I want to do a thorough A to E assessment and assess, is this patient acutely unwell? Are they septic, or are they physiologically doing well with some localised signs of infection, potentially, around this presumed pseudoaneurysm? If they’re critically unwell, I’m going to want to start resuscitating them as soon as possible. I can start that on the ward or in the anaesthetic room if urgency dictates.

Once I’ve reviewed them and I’ve satisfied myself that I’ve started appropriate resuscitation as needed, I want to start thinking about planning for the operation itself. So, there are several things to think about here. Surgical factors, patient factors, anaesthetic factors.

So, surgical factors – do we actually know what the pathology is here? Have we got appropriate imaging? What are the chances of life-threatening bleeding going to be once we start the operation? So, I’m going to make sure I’ve had a decent conversation with the surgeons about that and make sure that any investigations, such as imaging, are done before we go to theatre.

In terms of patient factors, there are multiple things to think about here. No matter what goes on, there’s a chance for significant blood loss here, so we need to make sure this patient’s group and saved. A previous IV drug user, so they may have chronic blood-borne virus infection. We want to make sure we check their virology and make sure that the appropriate precautions are taken if they do have blood-borne viruses. And they’re going to potentially be difficult for vascular access, which is going to be necessary for this surgery, and they may potentially need life-saving blood products and rapid resuscitation in the event of a significant bleed. So, that might require ultrasound-guided vascular access, for instance.

[04:04 – 04:42] Vascular Access Options

James: Sorry, you wanted to ask? Oh, yes, I do, yeah. What other options, you mentioned ultrasound, are available to manage difficult venous access?

Tom: So, we can, apart from peripherally inserted cannulas, for longer-term administration of medications, we can put in midlines and PICC lines. We can also put in central lines, particularly for acutely unwell patients and patients undergoing emergency surgery, because this can help with resuscitation and administration of vasopressors if needed, particularly if the patient’s septic or bleeding heavily. And we can consider the use of wide-bore central access if we think there’s a high risk of life-threatening bleeding, or if there’s evidence of ongoing bleeding.

[04:42 – 06:00] Hazards of Smoking

James: So, we mentioned this gentleman’s smoking. When considering an anaesthetic for this chap, what are the hazards of smoking that you’re concerned about?

Tom: So, if this gentleman’s a chronic smoker, he could potentially have chronic obstructive pulmonary disease, which would put him at increased risk under general anaesthetic. So, if he did have COPD, he’d have increased risk of post-operative complications, including chest infections, intraoperative complications like pneumothoraces, particularly if he has emphysematous COPD. And he’s going to have reduced physiological reserve, reduced respiratory reserve, and so he’ll be more at risk of hypoxaemia and resulting hypoxia intraoperatively from various causes.

He’s more likely to have reactive airways, and he’s more likely to have current chest infection as well, if it’s a background of chronic pulmonary disease. In terms of sequelae of pulmonary disease as well, he’s more likely to have peripheral vascular disease. He’s more likely to have cardiac sequelae as well, such as cor pulmonale, right heart failure, and pulmonary hypertension. This can be particularly dangerous when having a general anaesthetic.

So, any available investigations and information relating to this will be useful. So, you know, we’re going to make sure that we’ve had a 12-lead ECG on this chap. If he’s had any echocardiograms in the past for any reason, we’ll make sure we’ve seen the results of those.

[06:00 – 07:07] Blood-Borne Virus Precautions

James: OK, and you mentioned the concerns for blood-borne viruses. What precautions will you take?

Tom: The main precaution really is to make staff aware that he has a blood-borne virus, but the precautions we take will be the precautions we normally take. We’ll use personal protective equipment when performing invasive procedures on this gentleman, and it shouldn’t really affect the way we practice those procedures, but an awareness might lead to extra caution on behalf of individual team members.

But importantly, if there is an accidental needlestick injury or a surgeon cuts through a glove and potentially contaminates, then communicating their viral status can allow us to take quick and appropriate action. You know, letting the wound freely bleed, contacting occupational health, attending the emergency department if we need to, out of hours, gaining consent as early as possible to test the patient’s blood for current infection, and then obtaining appropriate prophylactic treatment as indicated.

[07:07 – 08:26] Post-Operative Pain Management

James: How might you approach his post-operative pain relief?

Tom: So, we know this chap has been an intravenous drug user. We want to know how recently he’s been using. If he’s been using large doses of heroin up until the day of admission, then we can be certain that he’s going to have high opiate requirements in order to manage his post-operative pain. If we suspect he’s going to need high doses of opiates, we want to try and minimise doses of opiates we’re using to try and minimise associated complications, such as respiratory depression, particularly if he has any pulmonary disease, and nausea and vomiting and things like that.

So, I would be strongly in favour of using magnesium as an adjunct, and I’d consider use of clonidine alongside. And if not clinically contraindicated, make sure that he has good doses of NSAIDs on board. I’d make sure he’s certainly having regular paracetamol as well. But if he’s been using opiates recently, and I suspect it might be difficult to predict how many opiates he needs, I would consider the planned procedure and certainly consider use of a PCA, at least initially, to keep on top of his pain.

James: Okay.

Tom: Regional techniques also would be useful for reducing post-op opiate requirements.

[08:26 – 10:12] Femoral Nerve Block Technique

James: And so, I’ll let you know that you’ve assessed the patient, and actually you think that there isn’t a terribly large amount of infection around the site, and that you think a femoral nerve block is a sensible move. Could you talk me through a femoral nerve block, please?

Tom: Sorry, give me a moment. A suprainguinal approach to a femoral nerve block is a standard approach given.

James: Femoral nerve block as opposed to fascia iliaca block.

Tom: Femoral nerve block can be administered on the medial side of the proximal thigh using ultrasound guidance. In order to do that, I want to, first of all, make sure the patient’s consented and understands risks and benefits. I want to make sure there’s no history of local anaesthetic allergy. I want to make sure they haven’t had any recent doses of local anaesthetic that might lead to local anaesthetic toxicity. Before the block’s performed, I want to do a stop before block. Make sure we’ve got the right side, that it’s marked. We’re doing it in the right location.

The block is then going to be administered by looking for femoral nerve sitting beneath sartorius and between adductor magnus and vastus medialis. It’s going to sit just lateral to the artery and usually superficial to the vein. This can be viewed with the ultrasound probe and can be injected around the nerve in an in-plane technique. And we can use Doppler in order to exclude the presence of any anatomical variant vessels that might lead to risk of bleeding.

James: How much local anaesthetic would you use and what?

Tom: I think for this sort of surgery, which can have an unpredictable length of time, I wouldn’t want to use anything really short-acting like prilocaine, but 0.5% bupivacaine at about 10 mls directly around the femoral nerve, appropriate volume.

[10:12 – 12:00] Local Anaesthetic Toxicity – Initial Management

James: OK, and as you inject your 20 mls of 0.375% bupivacaine, the patient says, “Oh, I don’t feel right, my lips are tingling and why is there an alarm going off?” What are you going to do?

Tom: So, I want to take an A to E approach to this first. I’m suspecting local anaesthetic toxicity, but I want to exclude other causes. Is this an anxious patient? Have they hyperventilated and caused some paraesthesia through that route? I’m going to quickly run through my A to E, are they already showing signs of hypotension? Do they have any arrhythmias on the monitor? And are there any other causes that I can identify?

If I’m convinced that there’s a high chance of local anaesthetic toxicity, I’m going to call for help, declare an incident.

James: And as you’re doing all that, he starts fitting. What are you going to do?

Tom: OK, so I’m going to… I’ve declared the incident. I’m going to get extra hands in the room. I’m going to designate someone to fetch intralipid, which we’re going to give… I can’t currently recall the dose. I’m going to manage the seizures with initial dose of 4 milligrams of IV lorazepam and monitor for response to that and give further doses if needed. And I can give infusion of propofol if needs be to help with the seizures. Intralipid is going to help absorb bupivacaine.

[12:00 – 13:53] Cardiovascular Collapse Management

James: Hmm. His blood pressure is 60 over 30. His heart rate is 38 beats per minute. He’s stopped breathing.

Tom: I’m feeling for a central pulse at this point. Is there any pulse?

James: He’s still got a carotid.

Tom: So he’s cardiovascularly unstable due to local anaesthetic toxicity. We’ve made sure that we’ve stopped administering any local anaesthetic in case the surgeons were doing that already. I want to give him some adrenaline at this point to try and bring up his heart rate and his blood pressure. I’d do that with approximately 1 microgram per kilo dose by drawing up 1 ml of 1 in 10,000 into 10 mls and administering boluses of that.

James: Mm-hm. Is that the first thing you would do?

Tom: No, it probably isn’t the first thing I’d do. I would repeat my A to E assessment. I would make sure that we’re giving adequate fluid resuscitation alongside this. I’d be giving fluid via a pressure bag. I’d make sure he gets 100% oxygen via our breathing system so that we’re maximising oxygen delivery. I would give him whatever vasopressors I had to hand initially. So if he’s bradycardic, probably ephedrine in this situation. I’d probably start with 12 milligrams and move up from there. And if there was a minimal or inadequate response to this, that’s when I would progress to giving dilute adrenaline.

James: Hmm. And just so you know, he has stopped breathing also.

Tom: Beg your pardon.

James: So he’s stopped breathing alongside the drop in blood pressure and the low heart rate.

Tom: At this point, I’d want to intubate this chap to protect his airway. If I thought that he just had low GCS, I could support his breathing, use a bag-valve-mask initially. But if he had truly lost consciousness and stopped breathing, I’d perform a rapid sequence induction with ketamine, rocuronium. Only those two agents would do if I was doing this rapidly. I could use some opiates alongside that if needs be, 200 micrograms of fentanyl potentially. And depending on his starvation status, I may ask for cricoid pressure whilst doing that. Once I’ve secured his airway and I’m happy with it, I’ll put him on the ventilator on volume control and I’m happy with his breathing and oxygenation. I’ll move on to managing his circulatory problem as described earlier.

[13:53 – 16:13] Cardiac Arrest and ALS Algorithm

James: OK. I’m going to show Tom an ECG. But the listeners, what does this ECG show?

Tom: It shows… Honestly, it’s too white. I believe that was asystole, but because of the…

James: Your belief and your eye of faith is correct.

Tom: OK. I couldn’t actually make out the line.

James: Sorry. I can’t make the lines any thicker. It’s very annoying. In spite of all your attempts, his persistent bradycardia becomes asystole. Asystole, what will you do?

Tom: So, if I haven’t already declared an incident and called for help, I’ll certainly do that now. We want to start CPR immediately. So we begin chest compressions at a rate of 30 to 2. In fact, if we’ve already intubated him, we can just ventilate him constantly and we can make sure we’ve checked his central pulses to see that it’s a true reading of asystole rather than disconnection or something of that nature. Once it’s confirmed, we’ll start chest compressions. Every other cycle, we’ll give him 1mg of IV adrenaline and think about causes.

James: And which side of the ALS algorithm are you on here?

Tom: We’re on the non-shockable side of the ALS algorithm because he’s in PEA arrest. So we give adrenaline straight away and then every other cycle. So while we’re continuing CPR and giving adrenaline, we need to think about causes of his arrest. So we thought it was local anaesthetic toxicity, but it’s important not to become tunnel visioned.

So could this be hypovolaemia? Has he had a massive bleed surgically that we’ve been unaware of because we’re behind a drape or something like that? We want to make sure we’ve checked for that. Is it hypoxaemia? Was there an issue with his breathing before he stopped breathing? Is there evidence that he actually desaturated prior to arresting? Has he had a PE or something like that?

But yeah, 4Hs and 4Ts. Hypokalaemia, hyperkalaemia, tension pneumothorax. We’re going to listen to his chest, look at his pressures. Tamponade, if possible, will get someone to do a FAST scan ultrasound and look at his heart and whether he’s hypothermic, which is unlikely as well.

[16:13 – 18:40] Physiological Effects and Prevention of LA Toxicity

James: Lovely. Yeah. What physiological systems are affected by local anaesthetic toxicity?

Tom: In terms of airway, it’s non-chronological, but when you lose consciousness, you can lose patency of your airway. In terms of your breathing, again, once CNS depression is caused, that leads to reduced… I’m going through this A to E, so again, breathing would be affected secondary to the effect on the CNS. Circulatory system, you can get arrhythmias and hypotension due to the effect of local anaesthetic on the conduction system and cardiomyocytes.

And central nervous system depression directly through sodium blocking action of local anaesthetics as well can lead to seizures and the CNS depression itself can lead to those other effects such as reduced respiratory drive, the patient being obtunded and essentially airway obstruction secondary to that.

James: And what precautions should you take to try to avoid local anaesthetic toxicity?

Tom: In order to avoid local anaesthetic toxicity, we should try, as we mentioned before, we always want to do a stop before a block, make sure it’s appropriate to be administering local anaesthetics when we do so for regional techniques. We should make sure that we’re administering standard concentrations rather than trying to mix and drop concentrations unnecessarily, especially a current problem with some problems with supply lines at the moment. There’s lots of mixing having to happen in theatres, which is a potential cause for error.

We want clear communication between team members, so surgeons and anaesthetists need to designate who’s going to be checking concentrations and doses of anaesthetic agents and communicate with each other when they’re being administered. And that should happen every time local anaesthetic is given. Often it’ll be the anaesthetist who will check concentrations and doses for the theatre staff who are making it available for surgeons to draw up as we’re used to doing those calculations.

Within the hospital itself, we want to make sure that we’re storing standard formulations of local anaesthetic products. So as far as possible, they should be colour coded, they should be consistent so that we’re not having different coloured ampoules from week to week. And we should have availability of NRFit systems so that accidental intravenous injection of local anaesthetic agents is minimised and we should have appropriate…

James: And that’s your time up, Tom. What was the last thing you were going to say?

Tom: I was just saying that we should have labels available so we can label us… kind of grasping at straws there. There’s a bit of an unstructured finish.

[18:40 – 22:00] Feedback – General Approach and Structure

James: It’s all good. You could divide it into environmental, patient and drug maybe if they’re thinking. How did you feel that went?

Tom: Yeah. Yeah. I was… Yeah, safety things. I mean, I guess, yeah, your assessment of the patient is important as well. I kind of forgot things because I was thinking more along the lines of systems and safety.

James: Yeah, exactly. Still reeling from jumping straight to using adrenaline on someone who’s a little bit hypotensive.

Tom: I mean, you weren’t far off being right. If it was 50, that’s where they on paper say do CPR and stuff and if you’ve got an impending disaster that’s clearly unfolding with abject rapidity, maybe it’s worth giving a tickle of adrenaline. The difference between one choice… The difference between doing that and not doing that will very much depend on information that’s hard to get across in a viva, I suppose. Like, what do they look like and how brown are your pants?

James: Yeah, definitely.

So my reflection from that is that you assumed that my next question after “here’s this patient, what are the problems that you might come across with this encounter?” You assumed my next question was “how are you going to anaesthetise this patient?” But in fact, it wasn’t going to be but you just piled straight ahead. And I think, give the examiner a chance to point you somewhere.

Tom: OK.

James: It would be maybe something I’d feed back for all of these stations is just give me, just drop in pauses where you give them a chance to get a toe in before you meander off talking very clearly and interestingly about something. Just let me have a chance to say, “OK, now tell me about this.”

Tom: Sure, yeah, yeah. I felt with that one, it felt like a lot to pack in for that scenario because there were, compared to some clinical scenarios, I felt that various things were clamouring for room in my head with that patient, you know, blood-borne, and I was, to be fair, you’re right, I was trying to think what routes are you going down here? Is it going to be safety around blood-borne viruses and then what to do after a needlestick injury because it could go down that route? Or is he going to be talking about major haemorrhage or is he going to be… so I was trying to put all those things in and I think I forgot to, and I’ve done this before as well, I think I forgot to say the basic anaesthetic history parts as well.

As well as my A to E and resuscitation, I want to make sure I take an anaesthetic history and you can quickly reel off the standard parts of that as well, which is probably only a few points, but if you don’t say it, it probably looks bad.

James: Because you just need to be able to, it’s like that, I think I’ve said before, it’s like, could you manage this situation at three in the morning when you’re dead tired? And the answer is yes, if you have a structure that you always fall back on that you need to demonstrate to them.

So yeah, literally, like, it’s good that you’re thinking where could this go, but then don’t decide which way it’s going to go because you might get tempted to talk about the thing you think you are most familiar with because that’s just a human thing to do, isn’t it?

[22:00 – 23:08] Feedback – Smoking Hazards

In terms of smoking, what did you have, I don’t know if you’ve got a mark scheme there, but what things, I never know how much to say because I’ve had this before.

Tom: Yeah, so you, I would think about it in terms of what are the side effects of smoking that are relevant to you. So the respiratory system, irritable airways, loads of secretions, and COPD, increased risk of post-op pulmonary complications. Cardiovascular system, so nicotine increases your heart rate, increases your blood pressure. So you’re going to either end up with stiffer vessels or an upset heart, a bit of LVH, etc.

I’ve also got down here, obviously it causes increased levels of carboxyhaemoglobin, reduced oxygen delivery, impaired wound healing, and also, it’s got, although I didn’t know this, I’ve learned this today, is it affects immune function and it can drop your circulating immunoglobulins and upset your white cells.

James: Really why it impairs healing as well, isn’t it?

Tom: Yeah, which are all biggies. But yeah, I should have just broken it down into systems and gone, respiratory, cardiovascular, they’re the big ones, aren’t they? And then after that, extra marks, yeah.

James: Mm-hmm. Yeah, pretty much. Yeah. Uh-huh.

[23:08 – 26:00] Feedback – Regional Technique and Drug Dosing

When talking about femoral nerve block, it’s probably worth breaking it down into what you tell them before you anaesthetise them on the ward. So, obtain consent, equipment, a trained person to assist me, ultrasound, an appropriate drug. Sterile probe cover, sterile needles, appropriate patient positioning, IV access and monitoring, like you’d do for any anaesthetic, prepping the site. And you mentioned you went into quite a lot of detail on the anatomy.

Tom: Yep.

James: I’d keep it a bit lighter and let me say, “so tell me about the anatomy of the femoral triangle in more detail” because I might not be interested.

Tom: Without, yep.

James: I liked how you compared and contrast anaesthetic drug choice. Just maybe be a bit quicker and then just straight up tell them what you’re going to do because there’s no real wrong answer unless you say like 500 mls of 0.5% bupivacaine. But otherwise the examiner’s like, “well, now I’ve got to ask them how much drug they’d use and really I want to move on but I need to push you to make a choice” because a lot of these stations, they push you to choose something and then commit to it and bear out the results of that, the right or wrong.

And then I think when we got onto local anaesthetic toxicity, you were jumping to sort it out and that’s fine but just slow down by like 5% and you’ll come across clearer. Like, use fewer words and pick better words.

Tom: No, I think that’s fair. I think I was rushed throughout that last one but, you know, that was very… I’m sorry.

James: Talk better about the things.

Tom: No, no. No, I think that’s fair. I could have slowed down and I would have remembered some of the core elements more such as whacking on 100% oxygen which is not necessarily always what you do clinically but, yeah.

James: And getting the quick reference handbook, get the QRH out because then you can say “I’m going to have someone who is going to go through that flowchart so we miss nothing” and then you don’t need to worry about quoting what the dose of intralipid is because it’s there in black and white.

Tom: Did you see me? I’m getting better at not saying out loud that I don’t know things because in my head I was going “I’m going to say the dose of intralipid” and I couldn’t remember it and I was like, “oh.” And previously I kind of, my brain’s… my mouth just sort of says what’s going through my brain and I go “and I’m not sure what the dose of that is” and then it just makes you sound less like you know what’s going on.

James: Yeah, I would just say “I’m going to give intralipid.” What is the dose of intralipid? Is it 5 mg per kg or something? I will find out and put it in the show notes for you, Tom, because I would reference the quick reference handbook. As it happens, James, I have the quick reference handbook on a chair behind me so I’m going to have a quick look myself and I’ll tell you.

[26:00 – 28:00] Feedback – Communication and A to E Assessment

Anything else sort of strike you to feedback there?

If I tell you something say it back out loud so his blood pressure is 60 over 30 when I said his blood pressure is low, his heart rate is low and he stops breathing, I would say “so you told me his blood pressure is low, his heart rate is 38 and he stopped breathing, okay” because you missed the stop breathing bit.

Tom: I totally… and it’s a weird thing as well because it’s definitely exam induced brain fog or something because I heard you say it, it’s not that I hadn’t heard you say it, it’s that I started talking in order of the things that I heard and then I kind of distracted myself and I forgot about the most important part and again, I think it comes back to the rushing that you were talking about and if I’d have repeated it back and slowed down by 5%, my brain would have gone “A comes before C” and then I probably approached it slightly differently, yeah.

James: I think, isn’t it House of God that says “in an emergency the first pulse you take is your own”?

Tom: I haven’t read it but yeah, probably.

James: Oh you should, it is a good book. The first time I found it very funny, the second time I found it incredibly harrowing because I read it during foundation but yeah, a good read for after your exams Tom.

Tom: Yeah.

James: It’s, your IV bolus dose is 1.5 mls per kilo over one minute, it’s around 100 mls for a 70 kilo, it says in the quick reference handbook, and then you start an IV infusion of 15 mls per kilo per hour. At 5, 1.5, then 10 times that but over an hour so it’s actually not that difficult to remember and then you give repeat doses every 10 minutes until you’ve restored cardiovascular stability at any time. After 5 minutes you can double the rate of the infusion as well based on judgement. It’s like here I’ll say it in as many words: do not exceed maximum cumulative dose of 12 mls per kilo. So 1.5 and then 15 and propofol is not a substitute.

[28:00 – 29:40] Summary and Closing

So the three takeaways from your clinical station should be: give the examiner a chance to get in there, slow your thinking down, and choose better words. And they’re all linked aren’t they?

Tom: We haven’t done many clinical things so I’ll try and take all of that…

James: No we haven’t, into consideration when we do another one a bit better.

Tom: Yeah we will because you’ll have picked better words.

James: That’s hard because you’re very eloquent Tom but you add in lots of extra words. What you need, what you need to do you see, what you need to do you see Tom, is think better thoughts and say better things. Maybe just be better.

Tom: As you can tell I’ve done a course in delivering feedback.

James: Yeah yeah, no need for a shit sandwich, just do a shit storm.

Tom: It’s all practice mate.

James: Yeah, okay, but no yeah, no it’s, I think it’s all good feedback.

Tom: Alright thanks very much James and I’ll see you next time.

James: Okay see you next time, bye.

Thanks for listening to the episode guys. If you found it useful or awful, please like and subscribe and rate the show. Definitely go check out the show notes on gasgasgas.uk. We all know this is a bucket of content. I want you to take some time for yourself and don’t overcook it, don’t freak out, keep studying.