In this episode I’ll:
1. Discuss an article about the rate of infusion for analgesic doses of ketamine.
2. Answer the drug information question “Is sodium polystyrene sulfate effective for the treatment of severe, acute hyperkalemia?”
3. Share a tip for responding to inpatient medical emergencies.
Lead author: Eben J Clattenburg
Published ahead of print in Academic Emergency Medicine
Ketamine is an effective analgesic but has more side effects when compared to opioids such as morphine. The authors compared the analgesic efficacy and incidence of side effects when low-dose (0.3 mg/kg) ketamine (LDK) was administered as a slow infusion over 15 minutes versus IV push over one minute.
The study was a prospective, randomized, double-blind, double-dummy, placebo-controlled trial. 59 adult patients were included. The primary outcome was the proportion of patients experiencing any psychoperceptual side effect over 60 minutes. An important secondary outcome was the incidence of moderate or greater psychoperceptual side effects.
Side effects were reported in 86% of the IV push group and 70% of the slow infusion group. There was a large reduction in moderate or greater psychoperceptual side effects in the slow infusion group. Only 43% of those patients experienced a moderate or greater psychoperceptual side effect compared to 76% in the IV push group. Specifically, regarding hallucinations, they were experienced by 27% of the IV push group vs 7% of the slow infusion group.
The authors concluded:
Most patients who are administered LDK experience a psychoperceptual side effect regardless of administration via SI or IVP. However, patients receiving LDK as a SI reported significantly fewer moderate or greater psychoperceptual side effects and hallucinations with equivalent analgesia.
While a slow infusion certainly lowers the risk of side effects with low-dose ketamine, an exceedingly high percentage of patients experienced side effects in both groups in this study. In my opinion, this re-inforces ketamine’s place as clearly second-line to opioids for analgesia.
Other studies have used a much lower dose of ketamine such as 0.15 mg/kg IV for analgesia. When opioids are absolutely contraindicated and ketamine is being used for analgesia, I would certainly try the lower dose first, and consider giving it by slow infusion.
Drug information question
Q: Is sodium polystyrene sulfate effective for the treatment of severe, acute hyperkalemia?
A: Probably not.
Sodium polystyrene sulfate (SPS) is a cation exchange resin, and in theory, trades a harmless sodium ion for a potassium ion in the lumen of the GI tract. While there is limited evidence, the best I can find suggests that this medication is no more effective than laxative use for lowering serum potassium levels.
SPS also has a risk of serious side effects. While not common, it can cause intestinal necrosis, a potentially fatal complication. Certain conditions lead to a higher incidence of intestinal necrosis from SPS and should be considered absolute contraindications to use:
- Postoperative patients
- Patients with an ileus or who are receiving opioids
- Patients with a bowel obstruction
For severe hyperkalemia the treatment of choice to remove excess potassium is hemodialysis.
Tip for responding to inpatient medical emergencies
Use the timer on your phone or smartwatch to keep track of the time between epinephrine doses during code blue calls. Time passes slowly in an emergency situation, and it is a natural instinct of the team to give epinephrine early. I have been in many codes where another dose of epinephrine is requested less than 1 minute after the last, instead of the ACLS recommended 3-5 minutes.
Too much epinephrine likely has the effect of increased myocardial oxygen demand, and limiting it to 1 mg every 3 to 5 minutes is a simple intervention a pharmacist can have at a code.
If you are interested in how pharmacists can respond to inpatient medical emergencies, I have an in-depth Code Blue and Rapid Response Training Program inside my Hospital Pharmacy Academy. Through this 6-module training program, you will develop the confidence and skills necessary to respond to code blue and rapid response calls. You will also be completely prepared to pass the healthcare provider BLS and ACLS classes. To learn more go to pharmacyjoe.com/academy.
If you like this post, check out my book – A Pharmacist’s Guide to Inpatient Medical Emergencies: How to respond to code blue, rapid response calls, and other medical emergencies.