IT morphine vs FNB single shot for TKA

[GaseousClay]

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Couple of our surgeons only want IT morphine rather than any PNB for their total knees. What do you think of this study?


Post-operative analgesia following total knee arthroplasty: comparison of low-dose intrathecal morphine and single-shot ultrasound-guided femoral nerve block: a randomized, single blinded, controlled study.
Frassanito L1, Vergari A, Zanghi F, Messina A, Bitondo M, Antonelli M.

RESULTS:
Patient characteristics were similar between the 2 groups. We found a statistically significant differences in postoperative pain between the two groups: ITM group had the lower visual analogic pain score (VAS) values. Morphine consumption was lower in the ITM group: average consumption within the first 6 hours was 0.9 mg in IT group compared to 3.1 mg in FNB group; at 12 h 4.2 mg vs 6.3 mg; at 24 h 6.9 mg vs 10.3 mg; at 48 h 9.7 mg vs 13.6 mg. However, the difference in the opiate consumption was not statistically different (p value = 0.06). Thirteen patients in ITM group experienced itching, only 5 in FNB group. We did not find any difference in the two treatment groups in the use of antiemetic and antipruritic medication. No cases of respiratory depression was recorded.

CONCLUSIONS:
Our results show that low dose of intrathecal morphine may be safe and more efficient than single-shot femoral nerve block for post-operative analgesia after total knee arthroplasty.

 

[BLADEMDA]

How about an adductor canal block combined with 100 ug of intrathecal Duramorph?

 

[GaseousClay]

although we would love to do that blade, our master aka surgeon says no blocks

 

[Twiggidy]

although we would love to do that blade, our master aka surgeon says no blocks

can't bite the hand that feeds you.....i know this all too well

 

[Twiggidy]

Now I would never venture myself to be a statistics genius, but if there was no significant difference between opiate consumption and side effects, how do they determine one is more safe and efficient vs the other. Again, sorry, I slept through stats day in med school.

 

[Monty Python]

RESULTS:
Patient characteristics were similar between the 2 groups. We found a statistically significant differences in postoperative pain between the two groups: ITM group had the lower visual analogic pain score (VAS) values. Morphine consumption was lower in the ITM group: average consumption within the first 6 hours was 0.9 mg in IT group compared to 3.1 mg in FNB group; at 12 h 4.2 mg vs 6.3 mg; at 24 h 6.9 mg vs 10.3 mg; at 48 h 9.7 mg vs 13.6 mg. However, the difference in the opiate consumption was not statistically different (p value = 0.06). Thirteen patients in ITM group experienced itching, only 5 in FNB group. We did not find any difference in the two treatment groups in the use of antiemetic and antipruritic medication. No cases of respiratory depression was recorded.

.

By no means am I a statistician, but I thought samples needed at least N=30 for statistical tests to be valid. This study had N=26 per group. Also the abstract does not mention specific p values (except for the difference in the opiate consumption as not statistically significant at 0.06). Rather the abstract says, " ... Statistical significance for all test was a p value < 0.05; ... We found a statistically significant differences in postoperative pain between the two groups." So was the p value 0.049999, or much much smaller and more predictive?

Also I cannot get into Pubmed to read the entire text; perhaps my above concerns were addressed there.

 

[Gas you down]

I gave intrathecal morphine once for a tka. 20 mcg. he was scary somnolent for about 18hrs.
70m. normal bmi. no osa or copd thank goodness.

 

[Mman]

What dose of IT Morphine were they using? I ask because giving any narcotics postop after IT morphine can become a bit problematic in terms of respiratory depression. The benefit of PNB is that it's local only so there is no mixing and matching routes of narcotics and respiratory depression profiles.

It's also such a small study you can't even begin to draw a conclusion.

Why didn't they measure any sort of patient satisfaction? On one hand they had lower pain scores with the IT morphine, on the other hand they had > 2x the rate of itching. And itching after IT morphine can be terrible. Did they end up with patients that had slightly less pain scores because they were so concerned with scratching their skin off that they forgot they were hurting?

 

[Ezekiel2517]

We've been using IT morphine for total joints quite a bit. I usually combine it with a block. But even with just the ITM, the pain control is great

 

[BLADEMDA]

Most of us use IT MSo4 for c sections. We all familiar with it. Side effects are mild with 100 ug of IT MSo4.

Still, in many of my patients (elderly or obese) I'd be a bit reluctant to choose that route over local injection by the surgeon combined with one of our typical blocks. I'm not a fan of IT opioids in the patient population I encounter for total joint replacement. Sure, a little Fentanyl maybe which lasts for 6 hours but not necessarily IT MSO4 which would last 18-24 hours.

Love to see a large study on the IT MSO4 technique with patients over the age of 80 or BMIs over 35.

 

[nap$ter]

where i trained and in my first job it was all FNB's +\- sciatic. works great.

in my current job it's all SAB/ITN/MAC. i was trepidatious at first, but it also works great. 150-250 ug duramorph or 50-75ug hydromorphone. some pts get PCA overnight. works great. in the 2 yrs i've been here zero respiratory complications.

 

[BLADEMDA]

where i trained and in my first job it was all FNB's +\- sciatic. works great.

in my current job it's all SAB/ITN/MAC. i was trepidatious at first, but it also works great. 150-250 ug duramorph or 50-75ug hydromorphone. some pts get PCA overnight. works great. in the 2 yrs i've been here zero respiratory complications.

What's your technique for an 85 year old getting a total knee?

58 year old with BMI of 45 getting a total knee?

I'm not sure 250 ug of IT duramorph is the best option in either of those cases.

 

[BLADEMDA]

J Med Assoc Thai. 2014 Feb;97(2):195-202.
Effects of single shot femoral nerve block combined with intrathecal morphine for postoperative analgesia: a randomized, controlled, dose-ranging study after total knee arthroplasty.
Kunopart M, Chanthong P, Thongpolswat N, Intiyanaravut T, Pethuahong C.
Abstract
OBJECTIVE:
Pain after total knee arthroplasty (TKA) is severe, thus adequate pain control can be a challenge. Intrathecal morphine (ITM) provides excellent postoperative analgesia for TKA, but may have side effects. Femoral nerve block (FNB) also has been used for postoperative analgesia in TKA. We examined postoperative analgesia efficacy and side effects of ITM combined with single shot femoral nerve block (SSFNB) after TKA, over the dosage range of 0.0 to 0.3 mg.

MATERIAL AND METHOD:
Sixty patients undergoing elective TKA received SSFNB (0.5% bupivacaine 20 ml) and spinal anesthesia with 15 mg of hyperbaric bupivacaine (0.5% Heavy Marcaine) were included in this study. They were randomized to receive ITM (0, 0.1, 0.2, and 0.3 mg). A patient-controlled analgesia (PCA) device provided additional intravenous morphine. Morphine consumption, pain score, and side effects were recorded at 0, 1, 4, 8, 12, and 24 hour postoperative. Patient satisfaction was rated at the 24-hour postoperative visit.

RESULTS:
Morphine consumption was significant higher in 0 mg ITM group (control) than other groups, but there was no difference between ITM groups. Pain score was significant lower in 0.3 mg ITM group compared to 0 mg at 1 hour (0.5 vs. 3.5, respectively; p-value = 0.013) and 4 hour (1.5 vs. 4.5, respectively; p-value = 0.037) postoperative period Side effects were not different in all groups.

CONCLUSION:
The present study concluded that, low-dose ITM combination with SSFNB provided good pain relief with low side effects and reduced morphine consumption during the first 24 hours post TKA.

 

[BLADEMDA]

http://www.europeanreview.org/wp/wp-content/uploads/786.pdf

Now you can read the entire study. I can tell you that their patients were significantly younger and thinner than the ones I encounter.

 

[BLADEMDA]

http://www.uic.edu/com/mcas/aa1709.pdf

These authors recommend 100 ug of IT MSO4 in patients over age 70 getting a total hip replacement.

 

[Ezekiel2517]

My advice would be to play it conservatively if you're worried about doing a spinal or giving ITM. In the grand scheme of things, it doesn't really matter what route you go. after the duramorph or block wears off, these pts are gonna be in pain for a while

 

[nap$ter]

What's your technique for an 85 year old getting a total knee?

58 year old with BMI of 45 getting a total knee?

I'm not sure 250 ug of IT duramorph is the best option in either of those cases.

i agree that 250ug of IT morphine is not a good idea for those two patients (although a BMI of 45 ain't always that bad in my eyes anymore...)

we use less ie "150-250 ug of duramorph"

 

[Noyac]

I have a couple issues with all of this. First, not every pt is the same and therefore we as physicians should tailor our treatment accordingly. Basically, what I'm saying is I hate the "one size fits all" approach.
My approach to TKA's has evolved over the years. I used to do FNB with spinal ITMS. Then I added a short acting ant.sciatic block with SAB ITMS. I started to realize that the ITMS was basically only adding SE's (itching and nausea) to a large portion of my pts. I also realized that my FNB lasted at least asking as the ITMS so why was I using the ITMS? I mostly discontinued the ITMS and they did better with just the FNB/ASNB. Less pruritis and Nausea. Especially the older pts. There are some robust pts that I may give it all too.

So a good FNB (0.5% Ropiv with 2-4mg decadron) lasts about 18-24 hrs give or take. ITMS last about the same so why use it if you are blocking the pt? If I did adductor canal blocks I would add the ITMS since the block quality is lower.

 

[Planktonmd]

Fem block + Lateral popliteal sciatic block + LMA

 

[GA8314]

Our surgeons are vehemently against FNB's. We do Adductor Canals and they don't work as well. We do FNB's and high popliteals for one surgeon and for most of residency, but there's a trend away from FNB's. I dislike the way ortho dudes get all excited after returning home from their conferences where they basically get all rev'd up based upon the latest person speaking at the seminar or the last study presented......