Toxidrome: Sympathomimetic, Anticholinergic, Cholinergic, Sedative-Hypnotic & Opioid

00:01 So let’s start off with sympathomimetics.

00:03 This is a pretty one to understand.

00:05 All the sympathomimetics do is up regulate the sympathetic nervous system.

00:10 So basically, they increase the heart rate, increase the blood pressure, generally produce sinus tachycardia.

00:18 Although in high doses, they can also precipitate tachyarrhythmias.

00:22 They don’t do a whole lot to respiration, although some patients may present with tachypnea And many patients will present with hyperthermia, largely due to the motor activity and agitation associated with sympathomimetic ingestions.

00:37 When you examine the pupils on these patients, they’ll be mydriatic.

00:40 So their pupils will be very large.

00:43 Their skin maybe normal but diaphoresis is quite common and their secretions are generally gonna be normal.

00:50 So again, this is a pretty easy toxidrome to understand.

00:53 It basically involves up regulation on the sympathetic nervous system, fast heart rate, high blood pressure, mydriasis, but generally not a lot of effects on skin or secretions.

01:08 By contrast, we have the anticholinergic toxidrome.

01:11 So as you can imagine, when you block the parasympathetic nervous system, you’re going to have unopposed sympathetic innervation.

01:20 So a lot of the features of the anticholinergic toxidrome are similar to sympathomimetics.

01:26 You’re gonna have a fast heart rate, a high blood pressure, a rapid cardiac rhythm, and in some cases, you may have tachyarrhythmias.

01:34 Generally, not a lot of effect on respiration but very commonly an elevated temperature.

01:39 This is actually an important feature of anticholinergic toxicity.

01:44 Much like patients with sympathomimetic exposure, you’re gonna have mydriasis, so large pupils.

01:51 However, this is where it gets different.

01:53 So these patients lose cholinergic innervation to the skin and the mucosa.

01:59 So they’re gonna have dry skin and more importantly, they’re gonna have almost no secretion.

02:05 So they’re gonna have dry mouth, they’re gonna have no tears, they’re gonna appear clinically to be very dehydrated.

02:13 So there’s a pneumonic for the anticholinergic toxidrome.

02:17 It’s mad as a hatter, cause these patients will all have altered mental status and agitation.

02:22 Blind as a bat, which refers to the very dilated pupils.

02:27 Red as a beet, which refers to the skin flushing that you commonly see in patients with anticholinergic ingestions.

02:34 Hot as a hare and I’m not really sure why hares are so hot, but this refers to the dry skin and elevated body temperature.

02:41 And then lastly, dry as a bone.

02:43 So these patients will have dry mucous membranes and a lack of oral and ocular secretions.

02:51 Now, it might not surprise you to hear that the cholinergic toxidrome is pretty much the opposite of the anticholinergic toxidrome.

02:59 So these patients will have a slow heart rate, a normal to low blood pressure.

03:05 They’ll typically be in sinus brady tachycardia, arrhythmias are very unusual with this toxidrome.

03:11 They’re gonna have some degree of respiratory depression.

03:14 Typically, a pretty normal temperature although they might be on the low side.

03:18 And their pupils are gonna be miotics.

03:20 So their pupils will be constricted, small.

03:24 So this is a really important differentiating feature of the cholinergic toxidromes.

03:28 These patients will be wet.

03:30 So their skin will be profusely diaphoretic and their secretions will be copious.

03:35 You’ll see lots and lots of secretions in the mouth, you’ll see lots of tearing.

03:40 And that’s because that’s what the parasympathetic nervous system does.

03:44 It basically innervates all of the parts of the body that produce secretions.

03:50 And you can easily remember the cholinergic toxidrome by thinking about fluids pouring out of every orifice.

03:58 So there’s a pneumonic for the cholinergic toxidrome that includes salivation, copious oral secretions.

04:04 Lacrimation, copious tearing.

04:06 Urination, these patients will commonly be incontinent of urine.

04:10 Defecation or diarrhea and unfortunately, that’s an area where they’re often incontinent as well.

04:16 GI dysmotility and emesis.

04:18 So basically you can imagine, there’s something rather pouring out of every orifice in this patient.

04:25 There’s another pneumonic which some people prefer that is includes diarrhea, urination, miosis or muscle weakness, bronchorrhea, bradycardia, emesis, lacrimation, and salivation.

04:41 Now, whether or not you use these pneumonics or however you think of the anticholinergic toxidrome, an easy way to remember it again, is if they have copious secretions, if there’s fluid pouring out of every orifice, you wanna be thinking about the cholinergics.

04:57 All right.

04:58 The sedative-hypnotics are pretty easy to understand because what they do is cause sedation.

05:03 So somnolence is gonna be the primary hallmark.

05:06 These patients sometimes can be so deeply sedated that they lose their airway protective reflexes so you do need to consider the possibility of intubation in some cases and respiratory depression might also occur.

05:19 So sometimes, these patients require mechanical ventilation.

05:23 There’s not a lot of autonomic effects associated with this sedative hypnotics.

05:27 But remember, patients often take multiple drugs at the same time, so they may have autonomic effects related to co-ingestions or other things that they took along with their sedative ingestion.

05:43 Opioids are very similar to the sedative-hypnotics in that they produce somnolence.

05:48 However, they universally produce miosis.

05:53 So opioids are very powerful pupillary constrictor.

05:57 And when you see pinpoint or very constricted pupils, you should always think about opioids.

06:02 The other thing to remember about opioids is that they very commonly cause respiratory depression.

06:07 So patients can come in apneic or with respiratory rates that are significantly low a nd this can be a fatal event.

06:15 So for these patients, we need to be pretty aggressive about treating them and restoring their normal respiration in order to save their lives.

06:24 All right.

06:24 So here’s the review of the toxidromes and I’m gonna highlight some of the things that differentiate them so you can remember.

06:30 Sympathomimetics, these patients will present hypertensive and tachycardic, and typically, their mental status will be agitated.

06:38 Anticholinergic patients will look alike a lot like sympathomimetic patients, except they will have very dry skin, very dry secretions.

06:48 By contrast, our cholinergic patients will be copiously wet.

06:53 They'll have diaphoretic skin, they’ll have increased secretions, and typically they will be somnolent rather than agitated.

07:02 Our sedative hypnotic patients will of course be sedated, and our opioid patients will also be sedated.

07:09 However, they’ll present with miosis and respiratory depression.

07:14 So hopefully, this will help you keep different clinical syndromes associated with different classes of drugs straight and allow you to rapidly narrow your toxicologic differential when you’re faced with a patient who has an exposure.