Anaphylaxis – Drug Induced Emergencies

00:00 The second disorder or emergency we're going to talk about is Anaphylaxis, which is actually a fairly common problem. It's a major allergic reaction which is life threatening and it's nearly always induced by drugs, but it can be induced by things such as latex. Some people develop latex allergies that can be very dramatic. The clinical signs are usually the result of massive amounts of histamine being released into the circulation of the body, along with some other allergic mediators. It's usually characterized by the appearance of sudden and severe hypotension and tachycardia for no apparent reason. And those may be the only signs you have. So you have to, again a bit like MH, you have to start thinking about what could be going on and start treating it early. It may be accompanied by bronchospasm, but it's not guaranteed. If the bronchospasm occurs, it may be very severe, so you have to be able to treat that.

01:01 Patients may develop a rash that will cover much of their body. And they may develop desaturation. The commonest cause of this during surgery is drug induced allergic reaction, as I mentioned, and it's usually to antibiotics or muscle relaxants, it's most commonly Succinylcholine, but increasingly we're seeing it as a secondary result of the use of latex in people who've had repeated surgical procedures and have developed a sensitivity to latex.

01:31 Rapid treatment with volume, in this case IV solutions and Epinephrine, no other drug, epinephrine only, reverses the reaction.

01:42 Initially, epinephrine is given in a dose of 0.3 mg to 0.5 mg intramuscular (IM) every 5 minutes.

01:50 Patients usually respond to 1st or 2nd dose.

01:53 IV infusion or boluses can also be given to support blood pressure.

01:56 They may however end up with very large volumes of IV solution on board, which may lead to problems such as pulmonary edema or cerebral edema. They often look like the Pillsbury Doughboy, they're really swollen up, very obviously increased in size by the time they've recovered from the actual anesthetic, from the Anaphylaxis. There's no point in giving antihistamines at any point during this reaction because every little molecule of histamine in the body has been released from the mass cells.

02:31 There is some value in giving steroids however. Not because they'll have an effect immediately, but they will have an effect down the road. So they'll help with bronchospasm, with the anaphylactic reaction itself over the next 6-8 hours. These patients also require ICU treatment, even if they look completely normal. Because full recovery can be followed within an hour or two hours, with a recurrence of the condition that, if the patients are not in the appropriate place, the condition could be fatal. Once you've made the diagnosis, you need to do allergy testing, get an immunologist involved, or an allergy doctor involved, and determine what caused the problem. And then be prepared for the patient to come back for another anesthetic, because they didn't get their surgery in the first place. I mean, you do not do surgery in the middle of an anaphylactic reaction.

03:25 And there are, that's a major issue in terms of dealing with these patients for the recurrent surgery.