Makingperipheral nerve

blocks work …for a really, really long

JC Gerancher MD

Professor and Section Head

Regional Anesthesia & Acute Pain Management

Medical Director of Surgical Services Informatics

Analgesia defined…

• Anesthesia• Motor block• Sensory block• “Analgesia= first request for additional

analgesia.”

Patient Satisfaction as an outcome of regional analgesia (not anesthesia)

• 7 of 10 RCT’s demonstrate improved patient satisfaction from post-op regional analgesia

• All of these 7 trials showed lower VAS pain scores

• None of 5 RCT’s demonstrate improved satisfaction from intra-op regional anesthesia

- Wu 2001

Local Anesthesia for PNB: No Free Lunch

Manufacturer’s Recommended Maximum Dose

(mg)

Mean Latency to Surgical Anesthesia (minutes)

Mean Durationof SurgicalAnesthesia

(hours)

Mean Duration of Postoperative

Analgesia (hours)

2-chloroprocaine(Nesacaine)

980 5-15 1-2 2-3

Lidocaine(Xylocaine)

490 7-15 2-3 3-5

Mepivacaine(Polocaine,Carbocaine)

400 10-15 3-4 4-6

Bupivacaine (Marcaine)

225 15-40 6-10 12-17

Ropivacaine(Naropin)

250 15-40 5-9 8-14

Local Anesthesia for PNB: No Free Lunch

Manufacturer’s Recommended Maximum Dose

(mg)

Mean Latency to Surgical Anesthesia (minutes)

Mean Durationof SurgicalAnesthesia

(hours)

Mean Duration of Postoperative

Analgesia (hours)

2-chloroprocaine(Nesacaine)

980 5-15 1-2 2-3

Lidocaine(Xylocaine)

490 7-15 2-3 3-5

Mepivacaine(Polocaine,Carbocaine)

400 10-15 3-4 4-6

Bupivacaine (Marcaine)

225 15-40 6-10 12-17

Ropivacaine(Naropin)

250 15-40 5-9 8-14

Mixtures for Supraclavicular block

0

5

10

15

20

25

Duration(hours)

latency(minutes)

2% lidocaine

0.5% bupivacaineplus epi

1% lido + 0.25%bupivacaine plusepi

-Bromage 1972

LA’s compared without epinephrine for fem-sciatic block

05

10152025303540

duration(hours)

latency(minutes)

2% mepivacaine

0.75% ropivacaine

0.5% bupivacaine

0.5% ropivacaine

0.5% levo-bupivacaine

-Casati 1998,2002

PNB Analgesia: Bupivacaine versus RopivacaineAuthor Type of PNB Equal dose? Epi used? Ropivacaine (hours) Bupivacaine (hours)

Junca Cervical Plexus R>B No 6 10Casati ISB R>B No 11 11Fanelli ISB R>B No 11 11Klein ISB R>B Yes 11 13Vaghadia SCB R>B No 11 12Bertini AXB Yes No 11 11Raeder AXB R>B No 12 13Liisanantti AXB Yes No 15 17Greengrass LPB-S Yes Yes 13 17McNamee F-S Yes No 13 15Fanelli F-S R>B No 11 14Connolly S R>B No 13 16

PNB LA choice and Analgesia

• Bupivacaine probably has a longer duration of analgesia

• You can’t make ropivacaine last longer by giving more of it

• Giving more than one drug probably makes sense.

• Local anesthetics choice is only one factor in the safe application of PNB.

• Is a very good idea• Positive effects

–Prolongs duration– Increases intensity–Reduces plasma levels (toxicity)–Marker of i.v. administration

Epinephrine in PNB

Increase in PNB duration (and maybe analgesia) with

epinephrine

0

20

40

60

80

100

Lido Mepiv Ropiv Bupiv

% increase inDuration

-Covino 1986, Weber 1999

33ml 0.5% Ropivacaine +/- Epi

- Hickey 1990

•Epino change in levels achieved with ropivacaine

•ropivacaine itself a vasoconstrictor

•Maybe why epi does not prolong ropivacaine block

Plasma Levels:

Duration

Clonidine for PNB

• Dose dependent prolongation of local anesthesia, analgesia

• Analgesia is independent of a systemic effect

• Mechanism: [alpha2]-Adrenoreceptor agonism, hyperpolarization-activated cation current.

© Karl Harrison, University of Oxford 2004

Clonidine analgesia for PNBAuthor Block Solution

Epi ?

Clonidine DoseControl

?Duration Without

Duration With

ReinhartAnkle (peds)

1.73% lidocaine No 140 mcg No 3 7

Singelyn AXB 1% mepivacaine Yes 0.5 mcg/ kg No 4 8

Iskandar Mid-H 1.5%mepivacaine No 50 mcg No 2 4

Casati AXB 0.75% ropivacaine No 1.0 mcg/kg No 13 15

Casati F-S 0.75% ropivacaine No 1.0 mcg/ kg No 14 17

El Saied AXB 0.75% ropivacaine No 150 mcg No 10 13

Hutschala AXB 0.25% bupivacaine Yes 2mcg/ kg Yes 1 7

Couture F-S 0.5% bupivacaine Yes 1.0 mcg/ kg No 12 12

Culebras ISB 0.5% bupivacaine Yes 150 mcg Yes 16 14

Clonidine analgesia for PNB• Prolongs shorter duration local anesthetics • 30-100 mcg is an effective dose • 30-100 mcg is unlikely to produce side effects• Clonidine may extend prolongation achieved

by epinephrine• Onset and quality of blockade is not impeded • Use with bupivacaine plus epinephrine?

‘Single Shot’: Proposed Maximal mean analgesia durations by

approach

02

46

810

1214

1618

CPB ISB SCB AXB POP F-S

First request foranalgesia (hrs)

Continuously Prolonged PNB: Is what we do usual?

• Exclusive use of stimulating catheters

• Inpatient infusions >> ambulatory infusions

• FNB > ICB > sciatic/popliteal >ISB

• ‘trifecta’ for TKA • All blocks done by CA-2 &-3’s

Dosing continuous PNB

• 0.2% ropivacaine and 0.25% bupivacaine at 0.1ml/kg/hr have been proven safe

• Unbound drug is the fraction of concern

• Little evidence for differential block

- Thomas 1999,Salonen 2000, Ekatodramis 2003

Continuous ISB

-Ilfeld 2004

No ‘clinically relevant improvements’ adding clonidine to cPNB?

• Worst and average VAS equal• Opioid consumption equal• Sleep disturbances equal• Side effects no different• Fewer patient controlled doses• More motor block from femoral cPNB• Are cPNB’s for chronic pain different?

-Ilfeld 2003, Capdevilla 2005

Continuous PNB Summary

• 0.2% ropivacaine has become most commonly used, but little studied

• Adjuncts probably have little utility• Basal rate of 7-10ml or 0.1ml/kg/hour• Patient controlled dosing popular

Impressive Multimodal Analgesia:COX-2 plus PCEA following TKA

Placebo Rofecoxib

PCEA requests (0-40 hours) 41 21Opioid consumption post PCEA 9 mg 6 mgVomiting 26% 6%VAS daily while in hospital 4 2VAS one week after discharge 4 3Degree flexion at discharge 73 84Degree flexion at one month 101 109

-Buvanendran, 2003

One dose of gabapentin for acute pain management:

Characteristics of studies

Number of studies found in the literature 22

Dose of gabapentin studied 300-1200mg

Degree of opioid sparing 20-62%

Mean 24 hour morphine sparing 30 mg

Numbers to treat (nausea) 25

Number to treat (vomiting) 6

Number to treat (urinary retention) 7

-Tiipana, 2007

-Gray 2006

U/S versus Nerve Stimulation

Technique Approach Block Time (min)

% ‘Success’

Onset Time (min)

Duration (min)

Williams2003

U/S+StimStim

SCB 510

8578

846652

Marhofer2004

U/SStim

ICB 100100

915

384310

Soeding2005

U/S+ “feel”“feel” alone

ISB andAXB

9590

672618

Liu2005

U/SU/SStim

122

678

839090

Where to Place Needles for the Best PNB technique:“Survey says..”

Where to Place Needles for the Best PNB technique:“Survey says..”