I gave this talk at the 2020 Winter Anesthesiology Meeting of the California Society of Anesthesiologists (#CSAHSWinter20).
My objectives were to:
1. Discuss adjuvants for extending single-injection nerve block duration;
2. Provide an update on continuous peripheral nerve blocks; and
3. Address practical considerations and present a strategy for personalized postoperative pain medicine.
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The Quest for Longer Block Duration: Techniques and Evidence
1. 2020 CSA Winter Anesthesia Conference
@EMARIANOMD
The Quest for Longer Block Duration:
Techniques and Evidence
Edward R. Mariano, M.D., M.A.S.
Professor of Anesthesiology, Perioperative & Pain Medicine
Stanford University School of Medicine
Chief, Anesthesiology and Perioperative Care
Veterans Affairs Palo Alto Health Care System
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Epinephrine
Vasoconstriction decreases vascular uptake
May decrease plasma concentration and potential for
systemic toxicity
Prolongs duration of lipophobic anesthetics (mepivacaine,
lidocaine) but not lipophilic long-acting anesthetics
– Ropivacaine already vasoconstrictive
Weber A, et al. A&A 2001;93:1327
<1
Day
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Clonidine
Clinically relevant prolongation of brachial plexus
anesthesia at 0.5 mcg/kg + LA1
– May be more pronounced with lipophobic anesthetics
– 1 mcg/kg prolongs ropivacaine duration with slight increase in
sedation2
Systematic review (27 studies)3
– Prolongs intermediate LA (mepivacaine) for select blocks
1. Singelyn FJ, et al. A&A 1996;83:1046 2. Casati A, et al. A&A 2000;91:388
3. McCartney C, et al. RAPM 2007;32:330
<1
Day
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Dexmedetomidine
Mean 261 min more sensory block
Mean 201 min more motor block (except
interscalene)
Mean 3 min faster onset when >50 mcg
Mean 289 min more analgesia (except
axillary), no difference at 24 hrs
Hussain N, et al. RAPM 2017;42:184
<1
Day
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Opioids
Peripheral opioid receptors exist: relevant for
intraarticular injections
No clear benefit for most opioids
– Results conflicting
– Opioid-induced side effects possible
Buprenorphine of interest
– RCTs have shown longer duration of analgesia when added to
LA1,2
– Not FDA-approved for nerve blocks
1. Candido KD, et al. RAPM 2002;27:162
2. Candido KD, et al. Anesth 2010;113:1419
<1
Day
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Dexamethasone
• RCT of ISB: 0.5% bupiv, epi, and clonidine 75 mcg ± dex
8 mg1
– Sensory block (24 vs. 14 hr, p<0.001)
– Motor block (23 vs. 14 hr, p<0.001)
• RCT of axillary blocks: 1.5% lido ± dex 8 mg2
• RCT of SCB: 1.5% mepiv ± dex 8 mg3
• Mechanism? Optimal dose? Off-label USA
1. Vieira PA, et al. EJA 2009;27:285 2. Movafegh A,et al. A&A 2006;102:263
3. Parrington S,et al. RAPM 2010;35:422
IV works just as well as
perineural
Fredrickson et al. RAPM 2013; 38: 300
Desmet et al. BJA 2013;111:445
Rosenfeld et al. Anaesth 2016;4:380
~1
Day
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Dexamethasone
May be different for distal brachial plexus
8 mg Perineural > IV for axillary1
– Mean 4.6 hr more motor block
– Mean 4.0 hr more sensory block + analgesia
5 mg Perineural > IV for infraclavicular2
– Mean 2.8 hr more motor block
– Mean 2.9 hr more sensory block
– Mean 3.5 hr more analgesia
1. Aliste J, et al. CJA 2017;64:29
2. Leurcharusmee P, et al. RAPM 2016;41:328
~1
Day
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Adjuvant Reliable Block
Duration >24 hrs
Epinephrine
Clonidine
Dexmedetomidine
Opioids except
buprenorphine
Buprenorphine
Dexamethasone
Based on actual studies; inspired by Dr. Patrick Wong, University of Ottawa
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Meta-analysis: CPNB vs. Opioids
Richman JM, et al. A&A 2006;102:248
Mean VAS
24h 48h
Infraclav 1.0 vs. 4.3 p<0.001 0.6 vs. 4.0 p<0.001
Interscal 1.4 vs. 3.6 p<0.001 0.5 vs. 2.3 p<0.001
Fem/LP 2.1 vs. 4.0 p<0.001 1.6 vs. 3.2 p<0.001
Sciatic 0.9 vs. 4.6 p<0.001 0.9 vs. 3.5 p<0.001
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Catheter Type and Migration
Steffel & Mariano, et al. K J Anesth 2017;70:72
Cadaver-based study
CON: 4/15 (27%) dislocated vs. CTN 0/15 (p=0.043)
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Securing the Catheter
Consider tunneling
Use an anchoring device1
Liquid adhesive
Clear occlusive dressing
Consider glue2
1. Borg & Mariano, et al. K J Anesth 2016;69:506
2. Klein SM, et al. Anesth 2003;98:590
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Summary
We discussed:
– Adjuvants for extending single-injection nerve block duration
– Update on continuous peripheral nerve blocks
– Practical considerations