ask the expert: practical advises for the use of regional ... · • upper extremity blocks – no...

Division of Anesthesiology, Balgrist University Hospital, Zurich

Forchstrasse 340, CH-8008 Zürich

www.balgrist.ch

Ask the Expert: Practical Advises for the Use of Regional Anesthesia

José A. Aguirre, MD, MSc

2nd SARA Annual Meeting

29th June 2013

[email protected]

Agenda

• General complications of regional anesthesia

• Regional anesthesia in patients at risk for compartment syndrome

• Adjuvants in peripheral regional anesthesia

• Regional anesthesia in patients with preexisting neurological diseases

• Neurological complications of pain catheters

• central catheters: 0.01% / 2 - 4.2: 100‘000Cook TM et al. BJA 2009; 102:179-90 (707‘445 central blocks)Pöpping DM et al. BJM 2008; 101:832-840 (14‘223 patients)

• peripheral catheters: 0.4 – 2%Barrington MJ et al. RAPM 200); 34:534-541 (7‘000 patients)Capdevila X et al. Anesthesiology 2005; 103:135-45 (1‘416 patients)Auroy Y et al. Anesthesiology 2002; 97:1274-80 (43‘946 patients)

• Peroneal palsy as complication of TKA: 0.3 -10%• Neurologic complications after THA: 0.08 – 7.6%

Indusuyi OB et al. JBJS Am 1996; 78:177-84Asp JP et al. Clin Orthop 1990; 261:233-7

Regional anesthesia and

complications

• Problems of ambulatory surgery

– Unplanned hospital visits due to pain and

PONV

– Readmission rate after general anesthesia:

7-27%

– Readmission rate after regional anesthesia:

4-13%

Williams BA et al. Anesthesiology 2004; 100:697-706Hadzic A et al. Anesth Analg 2005; 100:976-81

Peripheral catheters: the advantages

PONV: post anesthesia nausea and vomiting

• 18y, m, ASA 1

• Elective shoulder arthroscopy with rotator cuff repair right shoulder

• Beach chair position

• Patient wishes no pain after surgery and to sleep during the procedure

CASE

• RA in anesthetized

patient

• Winnie technique

• Bolus prior to catheter

insertion

• 5cm catheter over needle

tip

• Bolus injection on the

ward without test

• First nurse control 6h after bolus

Regional anesthesia in patients at risk of

compartment syndrome - the evidence

• 18y, m, ASA 1

• Trimalleolar fracture right ankle

• Uneventful general anesthesia and spinal anesthesia in the past for hernia repair and knee arthroscopy

• Patient wishes no pain after surgery

CASE

Compartment syndrome: Definition

Compartment syndrome: Definition

Ischemia – Reperfusion – Edema

� compartment p > capillary pressure

� arterial inflow & venous outflow

� further compartment pressure

� metabolic tissue demand > supply

� rhabdomyolysis and necrosis

Acute compartment syndrome

• 200‘000 diagnoses / year in the USA

• Majority from traumatic fractures– 40% tibial shaft fractures

– 23% soft tibial trauma

– 18% forearm fractures

• Incidence of ACS:– 4.3% after tibial shaft, 3.1% after diaphesal forearm,

0.25% after distal radial fractures

Whitesiders TE et al. J Am Acad Orthop Surg 1996; 4:209Konstantakos EK et al. Am Surg 2007; 73:1199-1209Olson SA et al. J Am Acad Orthop Surg 2005; 13:436-444Elliot KG et al. J Bone Joint Surg Br 2003; 85:625-32McQueen MM et al. J Bone Join Surg Br 2000; 82:200-203ACS: acute compartment syndrome

• Most common used

objective method in

clinical practice:

“Golden Standard”

• Difficult to use in

practice beyond 24h

Shadgan B et al. J Orthop Trauma 2008; 22:581-87Harris IA et al. J Trauma 2006; 60:1330-35

Compartment pressure

Janzing H et al. Eur J Trauma Emerg Surg 2007; 33:576-83

• Normal leg values

– Caucasians 0-15mmHg

– Nigerians 3-18mmHg (anterior comp.) /

3-14mmHg (deep comp.)

• Fasciotomy if

– Absolute pressure ≥ 30mmHg (- 45mmHg)

– DBP-CP = 10 - 20mmHg (≤ 30mmHg)

– Δ-P: MAP – CP ≤ 40mmHg

Compartment pressure

Ogunlusi JD et al. 2005; 25:200-02Mubarak SJ et al. Philadelphia: WB Saunders; 1981:113Whitesides TE et al. Clin Orthop 1975; 113:43-51Heppenstall RB et al, Clin Orthop 1988; 226:138Heppenstall B et al. Fractures in adults, 5th Ed. Lippincott W&W, 2001:332McQueen MM et al, J Bone Joint Surg Br 1996; 78:99

CP: compartment pressureDBP: diastolic blood pressureMAP: mean arterial blood pressure

Clinical symptoms

- pain (on muscle stretching)

- paresthesia, hypoesthesia

- paralysis

- pulselessness

- pallor

- reduced tenderness on palpationElliott KG et al. J Bone Joint Surg Br 2003; 85:625-32Kosir R et al. J Trauma 2007; 63:268-75Ulmer T et al. J Orthop Trauma 2002; 16:572-77

Compartment syndrome:

Assessment

Compartment syndrome and pain

Pain:

- an unreliable symptom: subjective / variable

- obviously, it does not avoid compartment

syndrome

- increasing analgesia demand precedes

neurovascular changes by 7.3h

- confounding factors: extremes of age, pain

thresholds, head injury/drugs, language barriers

- Pain not always present in ACS!Bae DS et al. J Pediatr Orthop 2001; 21:680-88

Benevides ML et al. Rev Bras Anestesiol 2006; 56:408-12Hailer NP et al. Acta Orthop 2007; 78:293-95Somayaji HS et al. J Arthroplasty 2005; 20:1081-83Nicholl JE et al. J Bone Joint Surg Br 1996; 78:812-13Badhe S et al. Injury 2009; 40:220-22

• 4 cases of compartment syndrome without any significant pain:– CS in the well leg after surgery for femoral

shaft fracture on the other side

– CS post-operatively following a tibial nailing for tibial fracture

– CS following tibial plateau fracture

– CS after closed, extraarticular multifragmentary fracture of the right prox. Tibia and fibula

CS: compartment syndrome

Compartment syndrome and pain

• Clinical signs:

• sensitivity 13-19%

• specifity 97-98%

• positive predictive value 11-15%

• negative predictive value 97-98%

Benevides ML et al. Rev Bras Anestesiol 2006; 56:408-12Hailer NP et al. Acta Orthop 2007; 78:293-95Somayaji HS et al. J Arthroplasty 2005; 20:1081-83Nicholl JE et al. J Bone Joint Surg Br 1996; 78:812-13Ulmer T. J Orthop Trauma 2002; 8:572-77Bae DS et al. J Pediatr Orthop 2001; 21:680-88

- Probability of compartment syndrome

with 1 clinical sign 25%

- Probability of compartment syndrome

with 3 clinical signs 93%

Clinical symptoms

- pain (on muscle stretching)

- paresthesia, hypoesthesia

- paralysis

- pulselessness (late sign!)

- pallor

- reduced tenderness on palpation

RA

Compartment syndrome and

regional anesthesia?

RA: regional anesthesia

General anesthesia and

compartment syndrome

• As pressure in the compartmentapproaches 10mmHg of diastolic BP, blood flow will cease

• Probably this may occur within 20mmHg of diastolic BP in injured muscle tissue

�Potential concerns wiht hypotensive

anesthesia techniques

Whitesiders TE et al. J Am Acad Orthop Surg 1996; 4:209Elliot KG et al. J Bone Joint Surg Br 2003; 85:625-32Shadgan B et al. J Orthop Trauma 2008; 22:581-87

Several cases of orthognathic surgery using hypotensive

anesthesia techniques with compartment syndrome of the lower

extremity have been described:

• Bilateral anterior ACS after short fascial plastic surgery under general anesthesia

� bilateral peroneal nerve palsiesGodeiro-Junior CO et al. Arq Neuropsiquiatr 2007; 65:826

•Two cases of othognatic surgery in general anesthesia with unilateral ACS of the

lower extremities � ankle-foot orthosisStrickland SM et al. J Oral Maxillofac Surg 2000; 58:814

• One case of ACS of the lower extremity after Le Fort osteotomy in general

anesthesia � ankle-foot orthosisBeadnell SW et al. J Oral Maxillofac Surg 1988; 46:232

ACS: acute compartment syndrome

• No randomized-controlled trial comparingoutcomes in patients at risk of ACS withregional anesthesia vs general anesthesia.

• Therefore, clincial practice is only based on casereports and retrospective case series.

• � no national or international guidelines for best practice

• Practice: regional anesthesia leads to decreasein postoperative pain and to sensory blockademasking ACS…


regional anesthesia

Mar GJ et al. Br J Anaesth 2009; 102:3-11ACS: acute compartment syndrome

• Central nerve blocks– have never been inplicated in delaying

diagnosis of abdominal compartmentsyndrome. Increase in perfusion pressure and decrease in intraabdominal pressure

– EDA has been implicated in ACS of lower limbs

– no report of single shot SPA or EDA implicatedin ACS

– intraoperative Δ-P only reduced in GA (DBP↓) but not during unilateral SPA


regional anesthesia

Hakobyan RV et al. Acta Glin Belg 2008; 63:86-92

Mar GJ et al. Br J Anaesth 2009; 102:3-11

Kakar S et al. Scott Med J 2005; 50:158-59

Gonanao C et al. Anesth Analg 2006; 102:524-29

EDA: epidural anesthesiaSPA: spinal anesthesiaACS: acute compartment syndromeGA: general anesthesia

• Upper extremity blocks

– No published case of ACS after upper limb

regional anesthesia

– One published case of ACS diagnose thanks to

upper limb regional anesthesia: breakthrough

pain as main indicator


regional anesthesia

ACS: acute compartment syndromeMar GJ et al. BJA 2009; 102:3-11Aguirre J et al. Anesthesiology 2013; 118:1198-205

• Lower extremity blocks

– One case of an ACS duirng continuous ambulant

popliteal sciatic nerve block

• Increasing pain over 2 days

• Pain relieved after splitting the patient‘s cast

• Catheter remained in place until POD4

• Four weeks after cast removal, evidence of prior full-thickess skin ulceration on the anterior aspect of the

ankle

– ACS or tight cast injury?


regional anesthesia

Walker BJ RAPM 2012; 37:393-7ACS: acute compartment syndrome


– Three published cases of ACS after single shot

lower limb regional anesthesia

• femoral nerve block delayed ACS diagnosis after

intramedullar tibia nailing despite pain being a significant symptom

• femoral nerve block delayed ACS diagnosis afterintramedullar femoral nailing

• ankle block delayed ACS diagnosis after forefoot

arthroplasty despite pain being a significant symptom


regional anesthesia

Mar GJ et al. Br J Anaesth 2009; 102:3-11

Uzel AP et al. Ortho & Trauma: Surg and Res 2009; 95:309-13 ACS: acute compartment syndrome


– One published case of ACS after continuous

femoral and sciatic nerve block:

• Distal femur and proximal tibia osteotomy with

external fixation of the right leg.

• General anesthesia

• Continuous femoral nerve block and continuoussciatic nerve block with 0.2% ropivacaine, 10ml/h


regional anesthesia

Cometa MA et al. Pain Medicine 2011; 12:823-28

Adjuvants for peripheral regional

anesthesia

• 48y, m, ASA 2

• Hallux valgus repair right foot

• Controlled arterial hypertension, increasedalcohol intake, moderate peripheralneuropathy

• No prior anesthesia

• Patient wishes no pain after surgery

CASE

Buerkle H. Best Pract Res Anaesth 2000; 14:411-18Niemi G. Best Pract Res Anaesth 2005: 19:229-45Buvanendran A et al. Best Pract Res Anaesth 2007; 21:31-49Christiansson L. Period Biol 2009; 11:161-170

Why adjuvants for LA?

• Shorten the onset time of LA action

– Only for central blocks?

• Limit the absorption of LA

– Decrease of spinal cord blood flow?

– Risk of peripheral neuropathy?

– Nausea and vomiting ?

• Improvement of block intensity/duration

– Clinical evidence?

LA: local anesthetic

Nerve

Artery

VeinNeedle

LA

97- 98%

2-3%

Systemic resorption depends on local blood flow!

Heavner JE. Curr Opin Anaesthesiol 2007; 20:336-42. ReviewCox B et al. Best Pract Res Clin Anaesthesiol 2003; 17:111-36

- 30%

Limit the absorption of local anesthetic

Improvement of block intensity:

clonidine

Analgesic benefit from the addition of clonidine to

local anesthetics? YES

Mechanisms of action?

- Centrally mediated analgesia?

- α2-mediated vasoconstriction in the periphery?

- Clear: not α2-mediated block prolongation but

inhibition of hyperpolarization-action current.

Effect more profound in C-fibers.

Buerkle H. Best Pract Res Anaesth 2000; 14:411-18Brummett CM et al. Int Anesthesiol Clin. 2011; 49: 104–16Pöpping DM et al. Anesthesiology 2009; 111:406-15McCartney CJ et al. RAPM 2007; 32:330-338Leem JW et al. RAPM 2000; 25:620-25

Side effects :

• Hypotension

• Bradycardia

• Sedation

Less side effects compared to epidural/spinal administration.

Related to the dose and to plasma levels.

Optimal dose: 150μμμμg (adults).

Improvement of block intensity:

clonidine

Buerkle H. Best Pract Res Anaesth 2000; 14:411-18Brummett CM et al. Int Anesthesiol Clin. 2011; 49: 104–16

Recommendations for the use of

adjuvants

Epinephrine: no use (as test dose??)

Clonidine: up to 150μg for adults

Dexmedetomidine: wait for better data

Buprenorphine / Tramadol: little efficacy

Dexamethasone: CAVE: dose-response-related neurotoxicity

Midazolam: CAVE: dose-response-related neurotoxicity

Brummett CM et al. Int Anesthesiol Clin. 2011; 49: 104–16

• Use the least toxic drug

– Spinal anesthesia: bupivacaine, chloroprocaine,

prilocaine.

– Peripheral: ropivacaine / bupivacaine (?), mepivacaine,

lidocaine.

• Avoid unnecessary risk with adjuvants

– NO epinephrine & lidocaine for central nerve blocks.

– NO tramadol / bicarbonate for peripheral nerve blocks.

– NO midazolam for peripheral neve blocks.

– NO adjuvants to ropivacaine. Clonidine??

Lirk P et al. RAPM 2012; 37:601-606Cuvillon P et al. BJA 2013; ahead of print

Recommendations for the use of

adjuvants

• Use perineural catheters for:

– extremely painful surgery (rotator cuff repair, total kneearthroplasty): ≥ 48h

– painful joint mobilisation (capsulotomy, synovectomy): ≥5d

– chronic pain patients and expected moderate to severepostoperative pain: ≥ 48h

– repetitive surgery (diabetic foot, wound controls): ≥ 5d

• Use perineural catheters only if:

– you and your team can manage them!!!

When to use continuous regional

anesthesia

Aguirre J et al. Anesthesiol Res Pract 2012 (online)Borgeat A, Aguirre J. Unintended Destinations of Local Anesthetics; 2012 Lippincott W&W, Philadelphia:196-204

Regional Anesthesia in the Patient

with Neurological Disease

• 28y, m, ASA 2

• Hallux valgus repair right foot

• Controlled arterial hypertension, Type 1 diabetes mellitus with implanted insulinpump, weak peripheral neuropathy

• No prior anesthesia

• Patient wishes no pain after surgery and issceptical against spinal anesthesia

CASE

The unanswered questions

• Do regional blocks worsen preexisting

neurological pathologies?

• Are LA more neurotoxic in this context?

• Does the failure rate increase?

LA: Local anestheticsBlumenthal S et al. Anesthesiology 2006; 105:1053-6Naveen E et al. Anesthesiology 2007; 107:177-178

Hebl JR et al. A&A 2006; 103:1294–1299

Double crush phenomenon


Chronic compression

segmental demyelination

nodal intussusception

bulbous myelin lesions

Increased vulnerability of a

distal lesion

Impairment in

axonal flow


Local anesthetics

Adjuvants

• Infectious risk of pain catheters

- local infection: 0 – 3.2%- proven systemic infection: 0 – 0.9%

Capdevila X et al. Anesthesiology 2009; 110:182-88 (12‘078 patients)

• SSI infections complicate 5% - 10% of all

surgeries increasing hospital length of stay by

48% - 310% and increase costs by 34% - 226%.

• Prevention of vasoconstriction at operation site

and increasing surgical-site tissue oxygen tension

with RA may reduce the occurrence of SSIs.

Impact on postoperative complications

Broex EC et al. J Hosp Infect 2009; 72:193-201Sessler DI et al. Anesthesiology 2010; 113:265-67Chang CC et al. Anesthesiology 2010; 113:279-84Kabon B et al. A&A 2003; 97:1812-17Buggy DJ et al. Anesthesiology 2002; 97:952-58

SSI: surgical site infectionRA: regional anesthesiaRCT: randomized controlled trial

• Neurological complications of pain catheters

• central catheters: 0.01% / 2 - 4.2: 100‘000Cook TM et al. BJA 2009; 102:179-90 (707‘445 central blocks)Pöpping DM et al. BJM 2008; 101:832-840 (14‘223 patients)

• peripheral catheters: 0.4 – 2%Barrington MJ et al. RAPM 200); 34:534-541 (7‘000 patients)Capdevila X et al. Anesthesiology 2005; 103:135-45 (1‘416 patients)Auroy Y et al. Anesthesiology 2002; 97:1274-80 (43‘946 patients)

• Peroneal palsy as complication of TKA: 0.3 -10%• Neurologic complications after THA: 0.08 – 7.6%

Indusuyi OB et al. JBJS Am 1996; 78:177-84Asp JP et al. Clin Orthop 1990; 261:233-7


complications

• Peripheral nerve injuries due to regional

anesthesia are often transient:

�mild paresthesias present in about 15% of

patients after peripheral nerve blocks

�most symptoms resolve within days to weeks

�99% complete resolving within 1 year

• Most neuraxial injuries are often permanent:

�15% - 80 - 100% permanent injuries

�frequency highly dependent on the type of

neural lesion Liguori GA. J Neurosurg Anesthesiol 2004; 16:84-86Borgeat A et al. A&A 2001; 95:875-80Neal JM et al. RAPM 2002; 27:402-28Auroy Y et al. Anesthesiology 2002; 97:1274-80Auroy Y et al. Anesthesiology 1997; 87:479-86Lee LA et al Anesthesiology 2004; 101:143-52


complications

Classification of neuromuscular

diseases

• Neuromuscular diseases (NMD)

– pre-junctional diseases (motoneurons and

peripheral nerves)

• ALS, MS, Guillan-Barré-Syndrome

– junctional diseases (synaptic transmission)

• myasthenia gravis

– post-junctional diseases (muscular)

• muscle dystrophies

• myotonies

ALS: amyothrophic lateral sclerosisMS: multiple sclerosis Papenfuss T et al. Anästh Inten Notfall Schmerz 2009: 44:766-771

Anesthetic risk factors of

neuromuscular diseases

• Cardiopulmonary comorbidities.

• Dysphagia � danger of aspirationpneumonia.

• Possible pulmonary dysfunction.

• Muscle relaxants: unpredictable durationof action.

• Volatile anesthetics: negative inotropeeffect.

Papenfuss T et al. Anästh Inten Notfall Schmerz 2009; 44:766-771Finsterer J et al. Cardiology 2000; 94:1–11Klingler W et al. Neuromuscul Disord 2005; 15:195–206Meißner S et al. Anästh Intensivmed 2009; 50:223–241



• Advantages

– avoidance of negative inotrope drugs and muscle

relaxants

– maintenance of spontaneous breathing

– hemodynamic stability

• Concerns

– double crush theory

– case reports of adverse neurological outcome

– no controlled, randomized studies

– non-binding guidelines

Upton AR et al. Lancet 1973; 2:359–362Radwan IA et al. Anesth Analg 2002; 94:319–324

• Pro RA

– Junctional and post-junctional diseases: no

damage of neurons: no absolute

contraindication for RA

– Pre-junctional diseases: Hebl et al. found a

low risk for central regional anesthesia

techniques. No absolute contraindication for

RA. Individual decision for patients with ALS,

MS, GBS etc.

Hebl JR et al. A&A 2006; 103:1294–1299Hebl JR et al. A&A 2006; 103:223–228Meissner S et al. Anästh Intensivmed 2009; 50:223–241

RA: regional anesthesiaALS: amyothrophic lateral sclerosisMS: multiple sclerosisGBS: Guillan-Barré-Syndrome



Demyelinating CNS disease:

Multiple sclerosis

• Most common demyelinating disease of the CNS. Motoneurons affected.

• Random, multiple sites of demyelination in the brain and spinal cord. Rareinvolvement of the peripheral nerve system, but described. Subtle nerve lesions wihtout real demyelination.

• Subclinical peripheral neuropathy (?)

CNS: central nervous system

Boerio D et al. Clin Neurophysiol 2007; 118:1735-8Pollocl M et al. Ann Neurol 1977; 2:41-48Vogt J et al. Ann Neurol 2009; 66:310-22Gartzen K et al. Eur J Neurol 2011; 5:789-91

Multiple sclerosis & general

anesthesia

• Autonomic dysfunction is frequent.

• Stress response may be associated

with relapse

– no difference in postoperative aggravationcompared to regional anesthesia (spinal)

• General anesthesia recommended if

– unclear disease progression

– no possible cooperation with a neurologistDrake E et al. Int J Obstet Anesth 2006; 15:115–123Bouchard P et al. Anesth Reanim 1984; 3:194–198Roissant R et al. Hrsg. Die Anästhesiologie. Heidelberg: Springer; 2004:1390–1391

• No real worsening after peripheral nerve block

– anesthetic plan influenced by case reports and personal experience

• Controversy concerning spinal and epidural

block

– effect of LA on demyelinated nerves

– systemic application of LA leads to discovery of non

diagnosed demyelinated areas

– typical symptons are aggravated temporarily

temporarily

Multiple sclerosis & regional

anesthesia

Borgeat A, Aguirre J et al. Anesthesiology 2008; 109:750-1Drake E et al. Int J Obstet Anesth 2006; 15:115–123Perlas A et al. Can J Anaesth 2005; 52:454–458Berger JM et al. Anesthesiology 1987; 66:400–402LA: local anesthetic

• Central regional anesthesia– Epidural anesthesia might be considered. Use

lowest LA dose possible. Avoid lidocaine. Ifadjuvants use clonidine / buprenorphine

– Consider spinal anesthesia only in cases of real advantage (C-section)

• Peripheral regional anesthesia– May be considered whenever possible, inform

patients about relapse possibility

Multiple sclerosis & regional

anesthesia

Confavreux C et al. N Engl J Med 1998; 339:285-291Vukusic S et al. Rev Neurol 2006; 162:299-309Dalmas AF et al. Ann Fr Anesth Reanim 2003; 22:861-64Bader AM et al. J Clin Anesth 1988; 1:21.24LA: local anesthetic

Peripheral neuropathy

• Multiple mononeuropathy: polyarteritis nodosa, SLE, sclerodermya, sarcoidosis, HIV, diabetes.

• Microorganisms (mononeuropathy): diphteria, Guillain-Barré.

• Toxic agents (polyneuropathy): sulfonamides, phenytoin, heavy metals, chemotherapy….

• Nutritional deficiency and metabolic disorders(polyneuropathy): alcoholism, perniciousanemia, diabetes…).

• Malignancy (polyneuropathy): multiple myeloma.

Diabetes: Concerns

• Oedema of the nerves may be directlyrelated to hyperglycemia.

• Microangiopathy may further lead to ischemia of the oedematous nerve and decrease blood flow and drug uptake.

• Prolonged exposure to local anesthetics.

Gebhard R et al. RAPM 2009; 34:404-07Kroin JS et al. RAPM 2010; 35:343-50

Preoperative evaluation:

• Interdisciplinary approach for cardiopulmonaldiseases– electrocardiography, X-Ray of the chest, lung

function if needed

• RA in the case of severe co-morbidities isthe first choice– epidural anesthesia for caesarean section in

patients with GBS

Baur CP et al. Anasth Intensivmed 2002; 37:77–83Meissner S et al. Anästh Intensivmed 2009; 50:223–241Alici HA et al. Int J Obstet Anesth 2005; 14: 269–270Brooks H et al. Anaesthesia 2000; 55:894–898

PNB: peripheral nerve blockRA: regional anesthesiaGBS: Guillan-Barré-Syndrome

Strategies to minimize risk in PNB

Preoperative examination:

• Exact neurological examination

– deficits must be documented

• Patients should be informed about

– technical difficulties

– possible relapses and/or progression

associated with stress, surgery and

anesthesia


• Technique of RA

– No superiority of US over NS described

– Adapt stimulation setting (>0.3mA, 0.3ms, 2Hz)

• Choice / concentration of LA– All LA are neurotoxic. Neurotoxicity

comparable at equipotent doses.

– Diabtic nerves more sensitive. Reduceconcentration, longer duration


RA: regional anesthesiaUS / NS: ultrasound / nerve stimulationLA: local anesthetic

• Role of adjuvants

– Epinephrine reduces blood flow in peripheral nerves � reduced wash out and prolonged LA exposure

– Clonidine may prove to be usefuladjuvants to prolong sensory block


LA: local anesthetic

• Goal: to inform practioners of regional anesthesia and pain medicine regardingthe etiology, differential diagnosis, prevention, and treatment of neurologiccomplications.

• Methods: extensive review of literature byspecialists on the field.

Hebl J et al. A&A 2010; 111:1511-19

• Ultrasound and neurostimulationequivalent.

• Reduction of dose, concentration, potencyof local anesthetic and reduction(elimination) of concentration of vasoconstrictive additive are potential considerations (based on animal studies).

Hebl J et al. A&A 2010; 111:1511-19

• Patients with pre-existing peripheralneurologic disease

– theoretic increase of the risk of new or

progressive postoperative neurologic

complications. No clinical data to confirm or

refute this theory

– individual risk/benefit assessment

Hebl J et al. A&A 2010; 111:1511-19

• Patients with pre-existing central neurologic

disease

– lacking clinical evidence for increase of risk of new or

progressive postoperative neurologic complications


• Spinal stenosis or mass lesions in spinal canal


– high local anesthetic volume neuraxial technique(EDA) might have a higher risk of progressive mass

effect compared with low volume technique (SPA)

Hebl J et al. A&A 2010; 111:1511-19

EDA: epidural anesthesiaSPA: Spinal anesthesia

• Overall approach to patients with pre-existing neurologic deficits:– these patients might be at increased risk of new or

worsening injury regardless of the anesthetic

technique

– if regional anesthesia is chosen, modifications of the

technique (dose, volume, concentration, drugs) mightminimize the risks

– limited human data neither confirm nor refute these

modifications

Hebl J et al. A&A 2010; 111:1511-19

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