Ultrasound and Regional Anaesthesia – Summary of Evidence
Part II Course, June 2012
Michael Barrington
St. Vincent's Hospital, Melbourne.
Introduction
Since 1994, there has been a steady increase in the number of peer-reviewed
articles published on the topic of ultrasound (US)-guided regional anesthesia.
This has grown from 1-2 articles per year in the mid-nineties to over 400 peerreviewed articles in 2011. This, together with the many conferences and
workshops dedicated to ‘US and Regional Anaesthesia’ indicate how US-guidance
has transformed regional anaesthesia. In routine practice, during 2006-09, the
Australasian Regional Anesthesia Collaboration (ARAC), documented USguidance (US alone or US combined with nerve stimulation (NS)) was utilized for
60% of peripheral nerve blockade (PNB).1 In 2011, US-guidance was used in
88% of procedures.2
The key utility of US-guided PNB is the ability to image the needle trajectory,
target nerves and surrounding structures. US-guidance provides a means to
observe real-time, the injection of local anaesthetic (LA) and enable adjustments
to improve its spread around target nerves and plexuses. Closer approximation
of nerve and needle tip and local anesthetic injectate should theoretically
improve block onset and block success. Potential reasons for preferring USguidance also include the perceived lack of reliability in traditional techniques of
nerve location, increased familiarity with US technology and having a visual
guide and endpoint during the procedure.
Liu has described other potential benefits of US-guidance including: 1. Increased
utilisation of regional anesthesia by personnel with a range of expertise (the
occasional regional anaesthetist) and experience (trainee); 2. Improved
knowledge of the mechanism behind block failure; 3. Avoidance of accidental
intravascular injection; 4. Reduced incidence of pleural puncture; 5. Reduced risk
of intraneural injection and nerve trauma; 6. Avoidance of or early recognition of
intramuscular injection; and 7. Improved understanding of the inconsistent
motor responses that occur during nerve stimulation.3 Many of these benefits
may never be tested by RCTs. For example benefits 1,2,6 and 7 are largely
qualitative, detecting intraneural injection is likely to depend on operator, probe,
patient and depth of target and cannot be detected with non-US techniques.
Comparative trials with outcomes (e.g. incidence of pleural puncture) requiring a
control group not utilizing US will be difficult to conduct because of the marked
trend towards US-guidance.
The Evidence for Efficacy
Important procedural indicators of efficacy include performance time, onset time,
quality and success. Overall US-guided PNB is associated with decreased
performance time usually defined as time interval between needle entry and end
of the injection. Antonakakis identified 11 of 19 RCTs where US-guided
techniques resulted in a decrease in performance time compared with
traditional techniques. Five RCT’s demonstrated no difference and three studies
involving ankle blocks demonstrated landmark techniques to be more efficient.4
Onset time is usually defined as the time interval from completion of injection
and complete sensory block. In 5 of 7 RCTs where onset time was the primary
variable US-guidance reduced the onset time.4 Quality is often described as
complete sensory blockade within a certain time period, often 30 minutes.
However if the block was intended as the sole anaesthetic, then conversion to
general anaesthesia or need for supplemental analgesics may be the marker used
for quality. Antonakakis identified 25 RCTs that measured quality or efficacy.
Overall, 15 of 25 trials demonstrated that US-guidance improved block quality
when compared with non-US techniques.4 No study has demonstrated that NS is
superior to US-guidance.
Systematic reviews and met-analyses have been performed comparing USguided with non US-guided techniques for PNB, with the results summarised in
Table 1. These have consistently demonstrated that US-guided techniques
improved efficacy outcomes when compared with traditional techniques.3,5-7
However, many RCTs are underpowered to detect an improved outcome when
success is defined as the surgery being performed without conversion to general
anaesthesia or requirement for supplemental analgesics.4 That is because of the
high success rates (95 -100%) reported in RCTs. Many of the RCTs are small,
diverse in control groups, techniques and anesthetics and have mostly been
performed where expertise exists and the external generalizability is unclear.
However a meta-analysis of 16 RCTs, published in 2011, demonstrated that USguidance results in a significant increase in success rate compared to all non-US
techniques.8 When compared with nerve stimulator techniques only, USguidance was still associated with an increase in the success rate. US-guidance
(vs all non-ultrasound) was associated with a significant increase in successful
brachial plexus (all) nerve blocks, sciatic popliteal nerve block, and brachial
plexus axillary block but not brachial plexus infraclavicular block.
In summary US-guided PNB consistently demonstrate improved performance
time, fewer needle passes, improved patient comfort, faster onset of block and
more complete block within the first 30 minutes. The majority of individual RCTs
are not adequately powered to evaluate differences in success rates. However,
success defined as surgical anaesthesia is improved with US-guidance compared
to a variety of traditional techniques at different anatomical locations in
metaanalyses.3,5
Table 1. Efficacy of US-guided PNB compared to other techniques for nerve localisation
Study
Liu 20093
Study type
Qualitative
systematic
review
Abrahams 20095
Metaanalysis
/systematic
review
McCartney 20106
Walker 20097
Qualitative
review
Cochrane
Systematic
Review
Gelfand 2018
Meta-analysis
Results
US significantly improved performance of blocks (time and number of needle
passes), the quality of sensory block (within first 30 minutes) but no difference
noted in surgical anaesthesia. 14 RCTs and 2 case series, however only 5 studies
measured block performance.
US-guided PNB associated with improved success [RR for block failure 0.41, 95%
CI 0.26-0.66, P<0.001], decreased performance time [mean 1 min less to perform
with US, 95% CI 0.4-1.7 min, P=0.003], faster block onset [29% shorter onset time,
95% CI 45-12%, P=0.001)] and decreased risk of vascular puncture [RR 0.16, 95%
CI 0.05-0.47, P=0.001] compared to traditional NS techniques, 13 RCTs.
Faster sensory block onset and greater block success when performing brachial
plexus block, 19 RCTs.
Concluded that US improves quality of sensory block (6 RCTs), motor block (4
RCTs), performance time (5 of 10 RCTs), and onset time of blocks (6 of 10 RCTs).
Studies not combined for metaanalysis because of a variety of PNB, techniques
and outcomes.
US-guidance resulted in a significant increase in success rate compared to all nonUS techniques [RR = 1.11 (95% CI: 1.06 to 1.17), P < 0.0001]; to NS techniques
only [RR = 1.11 (95% CI: 1.05 to 1.17), P = 0.0001]; brachial plexus-all [RR = 1.11
(95% CI: 1.05 to 1.20), P = 0.0001]; popliteal-sciatic [RR = 1.22 (95% CI: 1.08 to
1.39), P = 0.02]; axillary [RR = 1.13 (95% CI: 1.00 to 1.26), P = 0.05], 16 RCTs total.
US = ultrasound; PNB = peripheral nerve block; RCT = randomized controlled trial; NS = nerve stimulator; Success defined as
anaesthesia sufficient for surgery without requirement for additional PNB or general anaesthesia; RR = risk ratio; CI = confidence
interval.
Neuraxial ultrasonography has recently been introduced into clinical practice in
a few centres with special interest and expertise in the technique. A series of
RCTs have been performed evaluating the role of US in obstetric epidural block.
Prescanning parturients may reduce the number of needle passes and verterbral
interspaces required, but one operator performed all studies. Liu summarizes
these in a review3 and there appear to be no further RCTs in the literature since
that review was published in 2009 including the non-obstetric adult population.
Further research will be required to evaluate any advantages that US-guidance
may confer in terms of procedural success and other outcomes.9
There are very few RCTs that compare US-guidance to traditional techniques for
thoracic paravertebral, intercostal, transabdominis plane (TAP), rectus sheath,
ilioinguinal/iliohypogastric blocks.10 One RCT by Dolan compared US-guidance
with loss of resistance and demonstrated improved accuracy of local anaesthetic
injection using US.11 Most of the studies for trunk blocks are descriptive,
anatomical or comprise small case series. TAP blocks are almost entirely
administered using US-guidance explaining the lack of RCTs comparing USguidance with landmark technique using the lumbar triangle. There are several
RCTs comparing US-guided TAP with other analgesic techniques and these have
been subject to reviews.12,13
The Evidence for reduced local anaesthetic requirements and incidence of
side-effects
The use of US to monitor needle placement and spread of injectate may reduce
the amount of LA required to anaesthetise peripheral nerves. Reduced local
anesthetic requirements may reduce the risk of LA toxicity and reduce the
incidence of side-effects such a phrenic nerve paralysis. These results are
summarized in Table 2. Often the doses used in US-LA requirement studies are
significantly lower that those routinely used. The minimum effective dose of
ropivacaine 0.75% required to produce surgical anesthesia for rotator cuff
surgery has been calculated as 5 mL, however the author’s recommend against
the routine use of such a low volume because of the increased risk of failure.14 In
contrast, in a study of US-guided supraclavicular blockade the calculated volume
of LA required for US-guided supraclavicular block did not differ from those
required for conventional methods.15 A novel approach utilizing US measured
cross-sectional area calculated that a mean volume of 0.7 mL represented the
ED95 dose of 1% mepivacaine required to block the ulnar nerve at the proximal
forearm.16 Phrenic nerve block is a common side-effect of the interscalene and
supraclavicular approaches to the brachial plexus block. This is because of the
close proximity of the proximal brachial plexus and the phrenic nerve. USguidance results in a reduced incidence of phrenic nerve paresis compared to NS
techniques using the same doses of LA following either interscalene17 and
Table 2. Local anaesthetic requirements and specific side-effects during US-guided PNB.
First Author Year
Gautier 200914
Study type
validated up-anddown method
Duggan 200915
Renes 200917
validated up-anddown method
validated up-anddown method
RCT
Renes 200918
RCT
Marhofer21
RCT
O’Donnell 200922
validated up-anddown method
validated up-anddown method
RCT
Eichenberger 200916
Latzke 201023
Casati 200724
Results
Successful surgical anesthesia for arthroscopic shoulder surgery was achieved
with interscalene block, 0.75% ropivacaine, 5 mL or approximately 1.7 mL per
each of the 3 trunks of the brachial plexus.
Minimum volume required for US-guided supraclavicular block in 50% of
patients was 23 mL, and in 95% of patients was 42 mL.
The mean cross-sectional area of the nerves was 6.2 mm, ED95 volume was
0.11 mL mm2, 0.7 mL in total, volunteer study.
Two patients in the US group showed complete paresis of the hemidiaphragm,
but in the NS group, 12 patients showed complete and 2 patients had partial
paresis of the hemidiaphragm (13% versus 93%, respectively; P < 0.0001).
US-guided supraclavicular block, using 20 mL of 0.75% ropivacaine, was not
associated with hemidiaphragmatic paresis. 15 (50%) patients showed
complete paresis of the hemidiaphragm following NS-guided technique.
Mepivacaine 1% 0.11 ('low' volume) vs with 0.4 ('high' volume) ml.mm2
cross-sectional nerve area for ulnar nerve in axilla. The mean volume and
success rates were 4.0/14.8 mL and 90/100% in the low/high volume groups.
Successful ultrasound-guided axillary brachial plexus block may be performed
with 1 ml per nerve.
The ED(99) volume of local anaesthetic for sciatic nerve block was calculated
at 0.10 ml mm2 cross-sectional nerve area (2.8 – 10.2 mL), volunteer study.
ED 95 was 22 ml (95% CI, 13-36 ml) in group US, and 41 ml (95% CI, 24-66
ml) in group NS. 42% reduction in ropivacaine 0.5% for femoral nerve block.
US = ultrasound; PNB = peripheral nerve block; NS = nerve stimulator; RCT = randomized controlled trial; NS = nerve stimulator;
Success defined as anaesthesia sufficient for surgery without requirement for additional PNB or general anaesthesia; RR = risk ratio; CI
= confidence interval.
supraclavicular brachial plexus blocks.18 A case report describes a US-guided
phrenic nerve sparing interscalene block in a patient with contralateral
pneumonectomy.19 Other case reports describe low dose interscalene block with
5ml of bupivacaine 0.5% for bilateral procedures and when combined with
topicalisation of the airway for fibreoptic intubation.20 Minimal LA requirements
have also been calculated for the ulnar nerve at the axillary level,21 axillary
brachial plexus blockade22 and for sciatic nerve block.23 US-guidance reduces
local anesthetic requirements for femoral nerve blockade24
Anatomy and Vascular puncture
A detailed knowledge of anatomy and its variants is important for the safe and
effective practice of regional anaesthesia. Vascular puncture and haematoma
formation is consistently reduced with US-guidance.1,5 The Australian and New
Zealand Registry of Regional Anesthesia (AURORA) study has demonstrated that
US-guidance reduces the risk of vascular puncture most notably for femoral
nerve and axillary brachial plexus blockade.2 In particular, accidental vascular
puncture during femoral nerve blockade can result in significant morbidity. The
vascular anatomy relevant to femoral nerve blockade includes the lateral
circumflex femoral artery25 and if punctured, may result in significant
haematoma formation and morbidity. These vessels are readily located with USguidance and the needle trajectory can be altered to reduce the risk of vascular
injury. US-guidance is recommended for this technique. In the supraclavicular
region, US scanning reveals an arterial branch of the subclavian artery adjacent
to, or passing directly through, the brachial plexus in 43/50 (86%) patients, and
other variants have been documented. It is not uncommon for a prominent
dorsal scapular artery to bisect the neural structures resulting in inadequate
spread of LA.26
The Evidence for Safety
In 2010 evidenced-based critical review evaluated the contributions of US to
improved patient safety.27 Neal concluded that US reduced the occurrence of
vascular puncture and the frequency of hemidiaphragmatic paresis, however
there was at best inconclusive scientific proof that those surrogate outcomes
were linked to an actual reduction of their associated complications, such as local
anesthetic systemic toxicity (LAST).
Local anaesthetic systemic toxicity (LAST) is a serious and potentially avoidable
complication of LA administration that can cause central nervous system
excitation, seizures, cardiovascular collapse and death following direct
intravascular injection or delayed absorption of LA from the tissues. LAST was
recognized as a serious threat to patient safety shortly after the introduction of
cocaine into clinical practice28 and continues to be a source of serious morbidity
to this day. In a 2008 closed-claims analysis LAST was associated with 7 of 19
claims with death or brain damage.29 Potentially, US-guidance may limit LAST by
direct observation of intravascular injection, dose reduction and noting the lack
of injectate spread around the target. In addition, US-guided techniques are
incremental in nature whereby the spread of LA is assessed and re-assessed
before further injections. There have been case reports of early US detection of
inadvertent intravascular injection.30-33 By spreading out the time during which
the anaesthetic is injected the peak serum concentration may be reduced. The
risk of LAST may also be influenced by LA type, block procedure type, patient
factors and other factors.
Recently we have analysed LAST events from the Australian and New Zealand
Registry of Regional Anaesthesia (AURORA). The study period was January 2007
to March 2012 utilizing all data entered to a central database from an online
interface from centers with IRB approval. The study population comprised
19,163 patients [mean age 57.8 years (range: 13 - 103, SD 19.4), mean weight
80.0 kg (range: 22.6 - 210, SD 19) who received 24,191 blocks. 14, 269 patients
received a single block, 4,783 received two blocks and 111 received 3 - 4 blocks
per episode of anesthetic care. Type of PNBs comprised: upper limb 7220
(29.9%), trunk 3725 (15.4%), paravertebral 1491 (6.2%) and lower limb 11,689
(48.4). 21, 671 PNBs utilized a single anaesthetic and 2277 utilized a mixture.
Ropivacaine, lignocaine, bupivacaine, levobupivacaine and
lignocaine/ropivacaine were used in 77.3/6.8/3.8/1.7/9.1% of PNBs
respectively. US was used in 19,429 (81%) of PNB and not utilized in 4,562
(19%). The incidence of LAST was 0.87 per 1000 PNB (95% CI, 0.54 - 1.3:1000).
There were 21 episodes of LAST (12, minor; 8, major and one cardiac arrest).
Univariate analysis found US (P < 0.003), PNB category (P < 0.0005), and LA
dosage/weight (P < 0.0005) to be associated with LAST. PNB category (upper
limb, lower limb, trunk and paravertebral), use of US technology and LA dosage
were covariates in a multivariable logistic regression models used to evaluate
risk factors for LAST. Overall, paravertebral and upper limb blocks (compared
with lower limb) and increasing local anesthetic dosage were associated with an
increased risk of LAST. Prior to this analysis there had been no evidence that
either US-guidance or dose reduction reduced the incidence of LAST. This large
series provides the strongest evidence to date that US-guidance decreases the
incidence of LAST with an odds ratio of 0.21 (95% CI, 0.08 - 0.53, P = 0.001).34
In the abovementioned review on safety,27 Neal concluded that statistical proof
for a meaningful reduction in the frequency of rare complications, such as
permanent peripheral nerve injury, is likely unattainable. This statement stems
from the fact that neurological complications directly related to regional
anesthesia, especially those that are severe or disabling occur rarely.1,35-38
Existing RCTs are underpowered to detect statistical differences in nerve injury.
Other studies report surrogate markers of nerve injury such as paraesthesia
during or immediately following PNB or postoperative neurological features that
resolve relatively early in the postoperative period. The multicenter study by
Capdevilla39 documented an early incidence of neural dysfunction of 0.21% with
all resolved by 10 weeks (symptoms resolved in 1 of 3 patients at 36 hours) is
typical of the pattern of a relatively high incidence of early postoperative
neurological dysfunction followed by complete resolution. This is replicated in
other large series.40-43 Furthermore, perioperative nerve injuries (PNI) are
complex multifactorial events with patient, surgical and anaesthetic factors
contributing.40,42 Even in the presence of other definitive surgical and patient
factors, regional anaesthesia may be implicated.44,45 PNI is challenging to capture
and determine its aetiology because of the infrequency with which it occurs and
its multifactorial nature. Investigations such as nerve conduction studies may be
able to determine the type of injury (e.g. loss of myelin, axonal damage), severity
and prognosis however neurophysiological tests may not be able to determine
the exact mechanism and aetiology. PNI is multifactorial and determining
aetiology is demanding and in some cases impossible.44 The current risk of nerve
injury related to PNB is 0.4 per 1000 blocks (95% confidence interval, 0.081.1:1000).1 This cohort is primarily from a cohort of patients who received USguided blocks and the incidence is similar to that from earlier studies using NS.37
One important modifiable factor potentially reducing nerve damage in our
practice is intraneural injection. The current standard practice and
recommendation is to avoid intraneural injection.38 Intraneural injection may
disrupt the structural integrity of a peripheral nerve of particular concern being
fascicular injury, perforation of the perineurium, extrusion of the endoneurium
and axonal damage.46,47 There is evidence from animal studies that this does
occur. However, there is also clinical data that indicates that intraneural injection
does not inevitably result in nerve damage.48 A reasonable explanation for the
observation that nerve swelling during US-guided PNB does not necessarily
result in nerve injury, is that the injection is into the compliant connective tissue
(epneurium) that surrounds the fascicles. In contrast there are case reports of
nerve injury following US-guided PNB with intraneural injection.49,50 US-imaging
through its ability to document intraneural injection has stimulated a debate
about the risks associated with intraneural injection of LA during US-guided PNB
and also how we constitutes an intraneural injection. This debate has improved
our knowledge of peripheral nerve anatomy and led to a call for standard
nomenclature for intraneural injections.
Fortunately, regardless of technique used to perform block, the risk of serious
complications (LAST, nerve injury) related to PNB are infrequent or rare. When
considering the role of US-guidance in safety of contemporary practice we
should be reminded that safety in regional anaesthesia has never resided in the
use of one particular piece of equipment and that a range of clinical and nonclinical skills are important.
1.
Barrington MJ, Watts SA, Gledhill SR, Thomas RD, Said SA, Snyder GL, Tay
VS, Jamrozik K: Preliminary results of the Australasian Regional Anaesthesia
Collaboration: a prospective audit of more than 7000 peripheral nerve and
plexus blocks for neurologic and other complications. Reg Anesth Pain Med
2009; 34: 534-41
2.
http://www.anaesthesiaregistry.org: The Australian and New Zealand
Registry of Regional Anaesthesia (AURORA),
3.
Liu SS, Ngeow JE, Yadeau JT: Ultrasound-guided regional anesthesia and
analgesia: a qualitative systematic review. Reg Anesth Pain Med 2009; 34: 47-59
4.
Antonakakis JG, Ting PH, Sites B: Ultrasound-guided regional anesthesia
for peripheral nerve blocks: an evidence-based outcome review. Anesthesiol Clin
2011; 29: 179-91
5.
Abrahams MS, Aziz MF, Fu RF, Horn JL: Ultrasound guidance compared
with electrical neurostimulation for peripheral nerve block: a systematic review
and meta-analysis of randomized controlled trials. Br J Anaesth 2009; 102: 40817
6.
McCartney CJ, Lin L, Shastri U: Evidence basis for the use of ultrasound for
upper-extremity blocks. Reg Anesth Pain Med 2010; 35: S10-5
7.
Walker KJ, McGrattan K, Aas-Eng K, Smith AF: Ultrasound guidance for
peripheral nerve blockade. Cochrane Database Syst Rev 2009: CD006459
8.
Gelfand HJ, Ouanes JP, Lesley MR, Ko PS, Murphy JD, Sumida SM, Isaac GR,
Kumar K, Wu CL: Analgesic efficacy of ultrasound-guided regional anesthesia: a
meta-analysis. J Clin Anesth 2011; 23: 90-6
9.
Perlas A: Evidence for the use of ultrasound in neuraxial blocks. Reg
Anesth Pain Med 2010; 35: S43-6
10.
Abrahams MS, Horn JL, Noles LM, Aziz MF: Evidence-based medicine:
ultrasound guidance for truncal blocks. Reg Anesth Pain Med 2010; 35: S36-42
11.
Dolan J, Lucie P, Geary T, Smith M, Kenny GN: The rectus sheath block:
accuracy of local anesthetic placement by trainee anesthesiologists using loss of
resistance or ultrasound guidance. Reg Anesth Pain Med 2009; 34: 247-50
12.
Charlton S, Cyna AM, Middleton P, Griffiths JD: Perioperative transversus
abdominis plane (TAP) blocks for analgesia after abdominal surgery. Cochrane
Database Syst Rev 2010: CD007705
13.
Siddiqui MR, Sajid MS, Uncles DR, Cheek L, Baig MK: A meta-analysis on
the clinical effectiveness of transversus abdominis plane block. J Clin Anesth
2011; 23: 7-14
14.
Gautier P, Vandepitte C, Ramquet C, DeCoopman M, Xu D, Hadzic A: The
minimum effective anesthetic volume of 0.75% ropivacaine in ultrasound-guided
interscalene brachial plexus block. Anesth Analg 2011; 113: 951-5
15.
Duggan E, El Beheiry H, Perlas A, Lupu M, Nuica A, Chan VW, Brull R:
Minimum effective volume of local anesthetic for ultrasound-guided
supraclavicular brachial plexus block. Reg Anesth Pain Med 2009; 34: 215-8
16.
Eichenberger U, Stockli S, Marhofer P, Huber G, Willimann P, Kettner SC,
Pleiner J, Curatolo M, Kapral S: Minimal local anesthetic volume for peripheral
nerve block: a new ultrasound-guided, nerve dimension-based method. Reg
Anesth Pain Med 2009; 34: 242-6
17.
Renes SH, Rettig HC, Gielen MJ, Wilder-Smith OH, van Geffen GJ:
Ultrasound-guided low-dose interscalene brachial plexus block reduces the
incidence of hemidiaphragmatic paresis. Reg Anesth Pain Med 2009; 34: 498502
18.
Renes SH, Spoormans HH, Gielen MJ, Rettig HC, van Geffen GJ:
Hemidiaphragmatic paresis can be avoided in ultrasound-guided supraclavicular
brachial plexus block. Reg Anesth Pain Med 2009; 34: 595-9
19.
Jack NT, Renes SH, Bruhn J, van Geffen GJ: Phrenic nerve-sparing
ultrasound-guided interscalene brachial plexus block in a patient with a
contralateral pneumonectomy. Reg Anesth Pain Med 2009; 34: 618
20.
Smith HM, Duncan CM, Hebl JR: Clinical utility of low-volume ultrasoundguided interscalene blockade: contraindications reconsidered. J Ultrasound Med
2009; 28: 1251-8
21.
Marhofer P, Eichenberger U, Stockli S, Huber G, Kapral S, Curatolo M,
Kettner S: Ultrasonographic guided axillary plexus blocks with low volumes of
local anaesthetics: a crossover volunteer study. Anaesthesia 2010; 65: 266-71
22.
O'Donnell BD, Iohom G: An estimation of the minimum effective
anesthetic volume of 2% lidocaine in ultrasound-guided axillary brachial plexus
block. Anesthesiology 2009; 111: 25-9
23.
Latzke D, Marhofer P, Zeitlinger M, Machata A, Neumann F, Lackner E,
Kettner SC: Minimal local anaesthetic volumes for sciatic nerve block: evaluation
of ED 99 in volunteers. Br J Anaesth 2010; 104: 239-44
24.
Casati A, Baciarello M, Di Cianni S, Danelli G, De Marco G, Leone S, Rossi M,
Fanelli G: Effects of ultrasound guidance on the minimum effective anaesthetic
volume required to block the femoral nerve. Br J Anaesth 2007; 98: 823-7
25.
Muhly WT, Orebaugh SL: Ultrasound evaluation of the anatomy of the
vessels in relation to the femoral nerve at the femoral crease. Surg Radiol Anat
2011; 33: 491-4
26.
Muhly WT, Orebaugh SL: Sonoanatomy of the vasculature at the
supraclavicular and interscalene regions relevant for brachial plexus block. Acta
Anaesthesiol Scand 2011; 55: 1247-53
27.
Neal JM: Ultrasound-guided regional anesthesia and patient safety: An
evidence-based analysis. Reg Anesth Pain Med 2010; 35: S59-67
28.
Drasner K: Local anesthetic systemic toxicity: a historical perspective. Reg
Anesth Pain Med 2010; 35: 162-6
29.
Lee LA, Posner KL, Cheney FW, Caplan RA, Domino KB: Complications
associated with eye blocks and peripheral nerve blocks: an american society of
anesthesiologists closed claims analysis. Reg Anesth Pain Med 2008; 33: 416-22
30.
Baciarello M, Danelli G, Fanelli G: Real-time ultrasound visualization of
intravascular injection of local anesthetic during a peripheral nerve block. Reg
Anesth Pain Med 2009; 34: 278-9
31.
Dolan J, McKinlay S: Early detection of intravascular injection during
ultrasound-guided axillary brachial plexus block. Reg Anesth Pain Med 2009; 34:
182
32.
Martinez Navas A, RO DLTG: Ultrasound-guided technique allowed early
detection of intravascular injection during an infraclavicular brachial plexus
block. Acta Anaesthesiol Scand 2009; 53: 968-70
33.
VadeBoncouer TR, Weinberg GL, Oswald S, Angelov F: Early detection of
intravascular injection during ultrasound-guided supraclavicular brachial plexus
block. Reg Anesth Pain Med 2008; 33: 278-9
34.
Barrington MJ, Kluger R: Use of Ultrasound Guidance For Peripheral
Nerve Blockade is Associated With a Reduced Incidence of Local Anesthetic
Systemic Toxicity, Abstract accepted at American Society of Anaesthesiology,
Annual Meeting 2012. Washington D.C., USA, 2012
35.
Horlocker TT: Complications of regional anesthesia and acute pain
management. Anesthesiol Clin 2011; 29: 257-78
36.
Barrington MJ, Snyder GL: Neurologic complications of regional
anesthesia. Curr Opin Anaesthesiol 2011; 24: 554-60
37.
Auroy Y, Benhamou D, Bargues L, Ecoffey C, Falissard B, Mercier FJ,
Bouaziz H, Samii K: Major complications of regional anesthesia in France: The
SOS Regional Anesthesia Hotline Service. Anesthesiology 2002; 97: 1274-80
38.
Neal JM, Bernards CM, Hadzic A, Hebl JR, Hogan QH, Horlocker TT, Lee LA,
Rathmell JP, Sorenson EJ, Suresh S, Wedel DJ: ASRA Practice Advisory on
Neurologic Complications in Regional Anesthesia and Pain Medicine. Reg Anesth
Pain Med 2008; 33: 404-15
39.
Capdevila X, Pirat P, Bringuier S, Gaertner E, Singelyn F, Bernard N,
Choquet O, Bouaziz H, Bonnet F: Continuous peripheral nerve blocks in hospital
wards after orthopedic surgery: a multicenter prospective analysis of the quality
of postoperative analgesia and complications in 1,416 patients. Anesthesiology
2005; 103: 1035-45
40.
Borgeat A, Ekatodramis G, Kalberer F, Benz C: Acute and nonacute
complications associated with interscalene block and shoulder surgery: a
prospective study. Anesthesiology 2001; 95: 875-80
41.
Fredrickson MJ, Kilfoyle DH: Neurological complication analysis of 1000
ultrasound guided peripheral nerve blocks for elective orthopaedic surgery: a
prospective study. Anaesthesia 2009; 64: 836-44
42.
Candido KD, Sukhani R, Doty R, Jr., Nader A, Kendall MC, Yaghmour E,
Kataria TC, McCarthy R: Neurologic sequelae after interscalene brachial plexus
block for shoulder/upper arm surgery: the association of patient, anesthetic, and
surgical factors to the incidence and clinical course. Anesth Analg 2005; 100:
1489-95, table of contents
43.
Perlas A, Niazi A, McCartney C, Chan V, Xu D, Abbas S: The sensitivity of
motor response to nerve stimulation and paresthesia for nerve localization as
evaluated by ultrasound. Reg Anesth Pain Med 2006; 31: 445-50
44.
Hebl JR, Horlocker TT, Pritchard DJ: Diffuse brachial plexopathy after
interscalene blockade in a patient receiving cisplatin chemotherapy: the
pharmacologic double crush syndrome. Anesth Analg 2001; 92: 249-51
45.
Koff MD, Cohen JA, McIntyre JJ, Carr CF, Sites BD: Severe brachial
plexopathy after an ultrasound-guided single-injection nerve block for total
shoulder arthroplasty in a patient with multiple sclerosis. Anesthesiology 2008;
108: 325-8
46.
Hogan QH: Pathophysiology of peripheral nerve injury during regional
anesthesia. Reg Anesth Pain Med 2008; 33: 435-41
47.
Gadsden J, Gratenstein K, Hadzic A: Intraneural injection and peripheral
nerve injury. Int Anesthesiol Clin 2010; 48: 107-15
48.
Bigeleisen PE: Nerve puncture and apparent intraneural injection during
ultrasound-guided axillary block does not invariably result in neurologic injury.
Anesthesiology 2006; 105: 779-83
49.
Reiss W, Kurapati S, Shariat A, Hadzic A: Nerve injury complicating
ultrasound/electrostimulation-guided supraclavicular brachial plexus block. Reg
Anesth Pain Med 2010; 35: 400-1
50.
Cohen JM, Gray AT: Functional deficits after intraneural injection during
interscalene block. Reg Anesth Pain Med 2010; 35: 397-9