EMS A to Z: Ketamine for Pain 

Show Notes: 

From your hosts, Dr. Josh Gaither, Dr. Amber Rice, and Dr. Rachel Munn 

What is ketamine?  

It’s an NMDA receptor antagonist. It has does-dependent effects, but at “anesthetic” doses it acts as a dissociative anesthetic – meaning that the patient is dissociated from their environment.  

Ketamine also acts as an analgesic at lower doses without the dissociative effects of higher doses.   

 

So, does it work? How does it compare to morphine, which we’re all more familiar with...   

It does! It can actually be added to morphine for better and longer lasting pain control, but there’s not great evidence that one is superior or inferior to the other.   

 

We’re familiar with the side effects of opiates: hypotension, respiratory depression, nausea... what are some side effects of pain dose ketamine?  

At a pain dose, side effects like dizziness and nausea are most common. Ketamine can also cause some hypertension and tachycardia. At higher doses we think about things like emergence reactions, hypersalivation, emergence reactions.   

 

What patients may benefit from receiving ketamine rather than opiates?  

Patients with allergies to opiates  

Patients with hypotension   

Patients with a history of opiate abuse  

 

What is the correct dose of ketamine?  

0.2mg/kg    

Doses above this can increase the side effects including agitation, HTN, tachycardia...   

 

There are some myths about ketamine... can you give ketamine in patients with head injury?  

Yes, it has been debunked that ketamine increases ICP and worsens head injury in these patients.   

 

What about in patients with a history of psychiatric disease?  

Older studies demonstrated an increase in psychotic type symptoms at sub-dissociative (or pain dose) ketamine, however these symptoms abate when the ketamine wears off and do not appear to be long-lasting. 

 

Music by: Scott Holmes Music, “Brit Pop”