Hi everyone, I am back after hibernating for a couple of months. Today I want to talk about something that is relevant to all of us — something we all have been through which is how to not to convert to general anesthesia by prolonging the spinal block if the surgery runs longer than expected.
This topic crossed my mind because I just had a case of total knee revision last week and the case ran a lot longer than what I had anticipated. I timed my spinal for roughly about 3 hours max based on the surgeon’s past record, but the surgery went for approximately 5 hours due to various reasons. As it approached to 2 hours mark, I became a little antsy — I knew the spinal block would wear off soon and the surgery was not going to finish anytime soon. I didn’t want to irritate the surgeon in case the patient started to move. Preemptively, I started to give my patient IV precedex. Long story short, the case lasted 5 hours and my 2ml heavy marcaine 0.75% on a big 6′ tall guy (105kg) lasted till patient was in recovery. Patient only received 50mcg fentanyl before transferred out to the floor. He also didn’t get the nerve block preop nor pericapsular cocktail injection. He received total 90mcg of precedex and 50mg ketamine during the last 2.5 hours besides propofol running at 60mcg/kg/min. Patient was hemodynamically stable. My surgeon was utterly surprised with my super long spinal. He even asked me my recipe by the end of the case and I got his thumb up that day.
I tried precedex because it has analgesia property. After I finished that case, I did some research on precedex and found that there are many studies that have demonstrated the effects of IV precedex aka dexmedetomidine on prolonging the duration of spinal anesthesia. The MOA of dexmedetomidine acts at spinal level, laminae VII and VIII of the ventral horns of the spinal cord, thereby producing analgesia effects. In addition, it works by binding to α2 receptors in the locus coeruleus producing anxiolytic, sedative, analgesic, and sympatholytic effects. Several studies have shown that IV dexmedetomidine can prolong spinal anesthesia up to 50% duration. Hence, it is a great adjunct for us to use to prolong the spinal block.
Well now you know what you can do next time if you don’t want to convert to GA. Have a good rest of the week and I will write to you next week.
- Santpur MU et al. Effect of intravenous dexmedetomidine on spinal anaesthesia with 0.5% hyperbaric bupivacaine in lower abdominal surgeries: A prospective randomized control study. Anesth Essays Res. 2016 Sep-Dec;10(3):497-501.
Agrawal A, et al. Comparison of block characteristics of spinal anesthesia following intravenous dexmedetomidine and clonidine. J Anaesthesiol Clin Pharmacol. 2016 Jul-Sep;32(3):339-43. doi: 10.4103/0970-9185.188830.
3. Kubre J et al. Single dose intravenous dexmedetomidine prolongs spinal anesthesia with hyperbaric bupivacaine. Anesth Essays Res. 2016 May-Aug;10(2):273-7. doi: 10.4103/0259-1162.174465.
4. Lee MH et al. The effects of intravenous dexmedetomidine on spinal anesthesia: comparision of different dose of dexmedetomidine. Korean J Anesthesiol. 2014 Oct;67(4):252-7. doi: 10.4097/kjae.2014.67.4.252. Epub 2014 Oct 27.