manual of regional anesthesia

104 Pages·2007·0.98 MB·English

MANUAL OF REGIONAL
ANESTHESIA

Carlo D. Franco, MD
Chairman Orthopedic Anesthesia
JHS Hospital of Cook County

Associate Professor Anesthesiology and Anatomy
Rush University Medical Center

www.CookCountyRegional.com

Chicago, IL

Second Edition
2007
This manual is intended for the Anesthesiology Residents and Faculty of the
Department of Anesthesiology and Pain Management of Cook County Hospital. With the
exception of chapters on peripheral nerve blocks, which are written from the author(cid:146)s
direct experience, the rest of the material comes from his understanding and
interpretation, including actual quote, of the available literature. The author made every
effort to give proper credit to the sources.
The persons depicted in the pictures, models and patients, gave their written
permission to the author to have their photographs taken and used for the purpose of
teaching. Their decision was voluntary and did not involve compensation of any kind.
The photographs of cadaver material depicted in this manual come from dissections
performed by the author in the Anatomy Laboratory, Rush University Medical Center in
compliance with Rush University, State and Federal laws and regulations.
Care was taken to confirm the accuracy of the information presented in this
manual. However the author is not responsible for errors or omissions or for any
consequences from application of the information and techniques in this manual and
makes no warranty, expressed or implied, with respect to the contents of it.
This manual is in accordance with current recommendations as of April 2007.
However recommendations and guidelines change so the reader is urged to check for new
indications, warnings and precautions.
This manual was produced with the author(cid:146)s personal funds. No departmental or
grant money was used.
2
To my residents, who make my coming to work
intellectually challenging and pleasurable
and
to the memory of my father
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Chapter 1 Introduction

Chapter 2 Local Anesthetics

Chapter 3 Neuraxial Anesthesia

Chapter 4 Regional Anesthesia and Anticoagulation

Chapter 5 Peripheral Nerve Blocks

Chapter 6 Upper Extremity Blocks

Chapter 7 Lower Extremity Blocks
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CHAPTER 1
INTRODUCTION

General considerations(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133).. 6
Patient selection and premedication(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)...6
Monitoring(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)..............7
Outcome issues(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)...(cid:133)7
References(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)(cid:133)10

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General considerations

Regional anesthesia (neuraxial and peripheral nerve blocks) involves the
anesthesia of an area of the body (e.g., upper extremity) without necessarily affecting the
patient(cid:146)s level of consciousness. The practice of regional anesthesia is increasingly
popular in the United States and around the world. The recent introduction of ultrasound
to assist peripheral nerve blocks has started a new and exciting chapter in our
subspecialty where new technology is helping to make our practice more objective and
rational. In this manual I discuss several aspects related to the performance of regional
anesthesia according to the techniques most commonly used in the United States, but
with special emphasis in the techniques we perform daily at Cook County Hospital.
Regional anesthesia has been traditionally considered an (cid:147)art(cid:148). As such, it is
usually practiced by (cid:147)artists(cid:148) who use their particular talents to produce results difficult
to reproduce by (cid:147)non-artistic(cid:148) anesthesiologists. We have enormous respect for all the
pioneer practitioners who introduced and/or popularized the various regional anesthesia
techniques available to us now. We owe them a debt of gratitude. However in the 21st
century we should take advantage of all the technology available to us and favor science
over art when practicing regional anesthesia. The blocks that we perform and which I
describe in these pages are based mainly on facts (e.g., anatomical, physiological, and
pharmacological). The endpoints chosen are objective and the local anesthetic solutions
are used in volumes and concentrations considered adequate by clinical experience. After
controlling all possible factors we expect our results to be predictable and reproducible.
Regional anesthesia carries the risks and complications associated with use of
local anesthetics (i.e., local anesthetic toxicity), the risks and complications of using
needles and drugs in the proximity of nerves (e.g., neuropraxia, irreversible nerve
damage) and those risks associated with a particular technique (e.g., pneumothorax, total
spinal, etc).
As with any other anesthetic technique, choosing regional anesthesia requires a
thorough assessment that should include the patient, the surgeon, the nature of the
procedure and its estimated duration as well as the level of experience of the
anesthesiologist with regional anesthesia and its management.

Patient selection and premedication

The type of anesthesia for any procedure must be tailored to every individual
patient. There are patients who in general are not good candidates for regional anesthesia
especially if they remain awake (e.g., drug abusers, pediatric patients). On the other hand
we have a vast and successful experience with peripheral nerve blocks on drug abusers
and some pediatric patients, confirming that each case must be individually evaluated.
Judicious use of sedation increases patient(cid:146)s cooperation and acceptance. Sedation should
be used to calm anxiety, but not to turn the patient unconscious or otherwise
unresponsive. This is especially true in blocks performed close to the neuraxis like
interscalene blocks and lumbar plexus blocks. Keeping the patient lightly sedated, but
awake and cooperative makes the procedure easier for both the patient and the
anesthesiologist. A conscious and cooperative patient may also decrease the chances for
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complications (e.g., pain at injection, early subjective symptoms indicating impending
systemic toxicity, etc).

Monitoring

Every nerve block, whether it is performed in holding area, OR, PACU or office
must be treated as potentially dangerous. Monitoring blood pressure, heart rate and pulse
oxymetry as well as the establishment of IV access must always be considered.
Supplemental oxygen should be given especially when sedation is being used.
Resuscitation equipment, including oxygen, ambu bag, airways of different sizes,
intubation equipment and tubes along with appropriate resuscitation drugs must always
be readily available. A clear strategy to deal and treat complications must be in place. It is
always advisable before starting a technique to leave room at the head of the bed for the
anesthesiologist to manage the patient(cid:146)s airway in case this becomes necessary.
Familiarity with the surroundings helps when dealing with emergencies.

Outcome
Is regional anesthesia safer than general anesthesia?

Every discussion on regional anesthesia must address the issue of its relative
safety compared to general anesthesia. Despite several studies suggesting it and an
intuitive feeling that regional anesthesia seems (cid:147)safer(cid:146) than general anesthesia, no definite
and general answer can be given.
First of all most of the outcome studies have compared the relative benefits of
neuraxial anesthesia (spinal or epidural) versus general anesthesia in intra abdominal
surgery. Most of the studies lack the power (number of cases) to be able to see a true
difference, if there is one, and most of them are retrospective. Lack of randomization
raises the possibility of bias at the time of technique selection (e.g., sicker patients might
have received regional anesthesia more frequently, thus making the comparison with
general anesthesia more complicated). Other problems have to do with the parameter
chosen for comparison. If mortality is chosen the populations to study would have to be
extremely large to find a statistically significant difference since mortality under
anesthesia is extremely low. Other parameters like DVT, myocardial infarction,
pneumonia seem more adequate for comparison but their rates vary according to the
procedure and not just type of anesthesia. If physiological parameters are measured (e.g.,
PO2, O2 sat) there is evidence that these numbers are frequently better after regional than
general anesthesia, however their impact on morbidity is not clear.
Nonetheless, there is some degree of agreement that in certain procedures regional
anesthesia improves the outcome in a number of different ways like decreased rates of
DVT, PE and blood loss.

Surgeries most associated with improved outcome after regional anesthesia include:

1. Hip Surgery (hip fracture surgery and total hip arthroplasty): rates of DVT, PE
and blood loss are reduced after neuraxial anesthesia. The mechanism is
unknown, but may involve better peripheral circulation and less stasis.
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Mortality rates have been shown to be significantly lower with epidural anesthesia
as compared to general anesthesia.
2. Total knee arthroplasty: rates of DVT and PE are lower with neuraxial anesthesia.
3. Prostatectomy: similar reduction, possibly by a similar mechanism.
4. Peripheral vascular surgery: epidural anesthesia and postoperative epidural
analgesia have shown to improve graft patency after peripheral vascular surgery,
but does not seem to improve outcome after intra-abdominal vascular surgery.
Mechanism is not clear. Improve runoff due to vasodilatation or preservation of
normal coagulation has been mentioned.
5. Colon surgery: postoperative thoracic epidural analgesia with local anesthetics
has shown to enhance colonic activity after colon resection. If narcotics are used
in conjunction with local anesthetics this beneficial effect is lost.

Procedures were regional anesthesia has not shown benefits as compared to general
anesthesia include:

1. Upper abdominal and thoracic surgery, this is despite the fact that better pain
scores and times to extubation can be obtained.
2. Upper and lower extremity surgery: even though the patients may have a higher
degree of satisfaction and fewer side effects (nausea and vomiting) especially
immediately after surgery. This difference rapidly disappears at 24 h.

Airway and regional anesthesia

For some anesthesiologists managing a difficult airway usually means securing it.
This approach negates the benefits that regional anesthesia can provide when it is used
along with judicious amount of sedation. In our practice we have provided upper
extremity blocks to patients wearing halos and cervical collars when in our judgment the
advantages have outweighed the risks.
For more details please read Nigel Sharrock(cid:146)s chapter 2, Risks-Benefit Comparison
for Regional and General Anesthesia, In: Complications of Regional Anesthesia, edited
by Brendan T. Finucane.

An interesting study was published in December 2000 in the British Medical Journal
(not an anesthesiology journal) by Rodgers et al from New Zealand. The authors
reviewed the literature looking for randomized trials with or without use of neuraxial
anesthesia (spinal or epidural) before 1997. A total of 141 trials including 9,559 patients
were included in this meta-analysis. The following are the main findings:
1. Overall mortality was about one third less in the neuraxial group (103 deaths/4871
patients versus 144/4688 patients, P=0.006). This decrease was observed
regardless whether neuraxial was used alone or in combination with general
anesthesia.
2. DVT decreased by 44%
3. PE decreased by 55%
4. Transfusion requirement decreased by 50%
5. Pneumonia decreased by 39%
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6. There were also reductions in myocardial infarction and renal failure.

The authors concluded, (cid:147)Neuraxial blockade reduces postoperative mortality and
other serious complications(cid:148), adding that it is not clear whether these effects are due
(cid:147)solely to benefits of neuraxial blockade or partly to avoidance of general anaesthesia(cid:148).
Meta-analysis has the advantage of pooling large numbers so clinical events that are
infrequent can be studied. However it means putting together trials from different
institutions, including in some cases from different countries and different cultures. It
remains to be seen whether these very encouraging results can be duplicated and whether
they would apply more generally to regional anesthesia beyond neuraxial blocks (i.e.,
peripheral nerve blocks). Christopher Wu, from Johns Hopkins has shown the benefits of
regional anesthesia over general when non-traditional outcomes (other than morbidity
and mortality) like patient satisfaction, pain scores and the alike are measured. These so-
called (cid:147)soft(cid:148) parameters are having increased importance in today(cid:146)s practice.
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References

1. Sharrock NE: Risk-benefit comparisons for regional and general anesthesia in:
Complications of regional anesthesia. Edited by Finucane BT. New York,
Churchill Livingstone, 1999, pp 31-38
2. Wu C. ASA Newsletter, May 2005
3. Rodgers A, Walker N, Schung S et al. Reduction of postoperative mortality and
morbidity with epidural or spinal anaesthesia: results from overview of
randomized trials. Br Med J, 2000; 321: 1493-504
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