Acute behavioural disturbance
We discussed a couple of interesting ABD cases. We see ABD commonly in ED. Remember, it is not a diagnosis, it is a description of a clinical state that features a combination of extreme agitation, aggression and altered behaviour. There is a broad range of ways it can present, which reflects its many potential causes (ie wide differential).
These are very high-risk patients with potentially life-threatening pathophysiology, such as a severe metabolic acidosis, hyperadrenergic reaction, or cardiotoxicity.
Ketamine in ABD
Is ketamine ever contraindicated for rapid tranquilisation in severe ABD patients (ie posing an immediate risk to themselves and others)…? In short, the answer is no. Always use ketamine.
RCEM's ABD Best Practice Guideline acknowledges that ketamine may appear to contradict advice in the BNF—such as in patients who are hypertensive, hypovolaemic, or experiencing hallucinations. However, strong evidence supports its use in these circumstances, even in cases involving co-existing drug ingestion or head injuries. If you need control rapidly, always use ketamine.
Having said that… if a patient has worsening tachycardia or hypertension after receiving ketamine, this may increase cardiac risk due to synergistic sympathomimetic effects (e.g. in severe ABD secondary to cocaine toxicity). Additional treatment with benzodiazepines should be considered when this happens. Largely though, the sympathomimetic properties of ketamine are safe. Don’t be afraid.
IM ketamine dose
These patients are often too behaviourally disturbed to safely achieve IV access – therefore IM ketamine is your best bet.
If you’ve never given IM ketamine before it can feel like an uncomfortably massive dose. It’s a whopping 5mg/kg. To put that into context, a general anaesthetic dose of IV ketamine is 2mg/kg.
Interestingly, RCEM only suggest 4mg/kg. London’s Air Ambulance/PRU recommend 5mg/kg. Sydney HEMS also recommend 5mg/kg. I think the likely reason for prehospital services recommending the higher dose is there is an understandable emphasis on rapid scene control and safety. My view is we should apply the same philosophy in the ED – don’t underdose the IM ketamine dose.
So for a 70kg patient you should be giving 350mg. That’s a decent whack. Use the 50mg/ml (NOT the 10mg/ml) concentration and administer in two injections (can do at the same time if you have enough hands). Use both deltoids, thighs, or buttocks.
Decision paralysis
ABD is a highly stressful and time-critical scenario. Your sympathetic nervous system will be pumping. This sympathetic overstimulation can play out in a multitude of ways, including decision-paralysis. If you are experiencing a crisis of your own performance with the clock ticking, an excellent circuit-breaker is “Tactical Breathing”.
The only component of the autonomic nervous system that we can override and take conscious control over is our breathing. Deliberately slowing our respiratory rate in a moment of crisis prevents an escalating destructive sympathetic surge, and detaches the conscious self from the stressful moment, allowing an imaginary reset button to be pressed with subsequent restoration of mental bandwidth.
“Tactical breathing” (or “square breathing”) describes the four-second method pioneered by Lt. Col. Dave Grossman (author of On Combat – essential reading for Emergency Physicians). You breathe in for four seconds, hold for four, exhale for four and then hold again for four, on repeat until the mental clarity is restored. I’m really into this stuff.
Cheers all!
Robbie
@robbielloyd.bsky.social
