Regional anesthesia

What to learn?
 General principles
 Systemic complications with local anesthetics
 Complications of Peripheral nerve block
 Toxic effect of LA on nerve and surrounding structures
 Complications of neuroaxial blocks

Statement
No matter how skillful an
anesthesiologist may be, adverse peri-
operative events are inevitable in
anesthesia practice.

General principles
 Safe regional anesthesia begins with:
1. A thorough preoperative assessment of the patient.
2. Skilled intra-operative sedation and monitoring.
3. Regional anesthesia area in the OR where
equipment, monitoring, resuscitation drugs and
assistance are readily available.
4. Early identification and intervention are of the
utmost importance in preventing neurologic injury.

Standard of Care During
Regional Anesthesia
 Preoperative patient selection
 Informed consent
 Appropriate use of equipment and technique
 Monitoring regional anaesthesia practice
 Accurate and meticulous anaesthesia documentation
 Physician–patient communication
 Appropriate and timely postoperative follow-up

Patient Selection
Inappropriate patient selection:
 Some patients are not psychologically suitable for
regional anesthesia.
 Patients with severe mental illness.
 Neuraxial techniques in hemodynamic unstable.
 Patients with pre-existing neurologic disease.
 Patient refusal (explain in detail)

Consent
 Potentially serious complications associated with
regional anesthesia should be disclosed to patients,
including convulsions and the risk of cardiac toxicity
from systemic injections of local anesthetics, spinal
cord/nerve injury leading to paralysis or neurologic
deficit, pneumothorax, hematoma, infection, cardiac
arrest, and death.
 A recent study revealed that fewer than half of
anesthetists disclose the risks of seizures, respiratory
failure, and cardiac arrest before the administration of
either neuraxial blocks or peripheral nerve blocks.

Appropriate Equipment and Technique
 For years, percutaneously insertion of needles toward
neural targets relying on anatomy and techniques of
paresthesia and the loss of resistance (LOR).
 Nerve stimulation was an important advance providing
some evidence that the needle tip is close to the neural
target.
 Ultrasonography allows real-time visualization of
anatomical structures and offers the potential to guide
needle and catheter placement in regional anesthesia.
 To minimize risks combine ultrasound and nerve
stimulation techniques.

Monitoring Regional Anesthesia
 Standard ECG and pulse oximetry are essential monitors.
 A baseline blood pressure reading should be obtained and
Once the regional anesthesia procedure is complete, the
monitors should remain attached.
 In conscious patients, Et CO2 monitoring may not be used.
 Evidence of regressing blockade and stable vital signs must
be present to fulfill the criteria for discharge
 Patients receiving local anesthetic infusions should be
visited regularly by a qualified physician postoperatively.

Documentation
Detailed documentation of patient
consent and the clinical procedure is
very important.
Open and honest communication with
the patient is essential for providing
good quality patient care.

Physician–Patient Communication
 Patients may report anxiety, and appropriate preoperative
education for the patient can help mitigate this.
 Patients undergoing supraclavicular blocks should be
warned about the risk of pneumothorax.
 Caution patients about the risk of burns (ie, from
radiators) if sensory anaesthesia continues after discharge.
 Warn patients about lying on paralyzed extremities for any
length of time or letting them become dependent.
 Patients should receive written instructions when to seek
medical attention before discharge from the hospital.

Systemic complications
of local anesthetics
ALLERGIC REACTIONS
 Signs and symptoms are almost always associated with
amino ester preparations or preservatives.
 Nazir and Holdcroft found 797 from 331 from 96.
SYSTEMIC TOXIC REACTIONS
 Systemic toxic reactions to local anesthetic drugs occur
as a result of unintentional intravascular injection and
rarely follow the injection of an excessive quantity of
local anesthetic into an appropriate site.

 The lungs are an important eliminator for local
anesthetic drugs (an accidental intra-arterial injection
in the head, face, or neck region).
 Plasma concentrations of local anesthetics are
influenced by the (CO2) and the pH. An elevated
arterial CO2 tension increases cerebral blood flow, and
an acidotic state increases intracellular ion trapping
and the amount of free drug available.
 This combination of factors has a synergistic effect on
the seizure threshold.

 Rapid absorption;intercostal, epidural, brachial
plexus, lower extremity, and subcutaneous tissue.
 The addition of epinephrine to local anaesthetic drugs.
 Local anesthetics affect both electrical and mechanical
cardiac activity.
 Tachycardia and hypertension are early signs of cardiac
toxicity, and with increasing doses patients develop
bradycardia and hypotension.

Prevention
 The administration of epinephrine and isoproterenol
with the local anesthetic can aid in ruling out an
intravascular injection.
 Increased heart rate (>10 beats/min) and systolic
blood pressure (>15 mmHg) in addition to T-wave
changes (>25% decrease in Amplitude) are considered
sensitive and specific end points in response to an
intravascular injection of a test dose containing 15 ug
epinephrine.

Management (ABC)
Medications:
 Lipid emulsion (administer early):
Bolus of 1.5 mL × kg–1 iv over one minute
Infusion of 0.25 mL × kg–1 × iv min–1
Repeat bolus q3-5 min to a total of 3 mL × kg–1
 Bronchospasm/edema → antihistamines, corticosteroids,
bronchodilators
 Hypotension → fluid, epinephrine.
 Seizures → midazolam (0.05-0.1 mg × kg–1), propofol (0.5-1.5 mg
× kg–1), barbiturates (thiopentone [1-2 mg × kg–1])
 Ventricular arrythmias → amiodorone (300 mg initially, followed
by repeat 150-mg bolus 3-5 min later)

Complications of Peripheral
nerve block
DIRECT NEEDLE TRAUMA TO THE NERVE
 Typically neurapraxia injuries are observed
postoperatively when patients complain of persistent
numbness in the distribution of a peripheral nerve.
 Numbness gradually regresses over a period of weeks
and is rarely observed beyond 3 months.
 Regional anesthesia-related injuries may be the result
of needle trauma, injection pressure, or the toxic
effects of local anesthetics or additives.

nerve block
Prevention
 Some suggest that most neural injuries are associated with
either paresthesia or pain on injection.
 Needle damage or pressure generated during injection of
local anesthetics account for most of these injuries.
 Nerve damage occurred by both mechanical and chemical
injury during intraneural injections of neurotoxic
substances (ie, local anesthetics).
 Chemically induced damage is also possible from high
concentrations of local anesthetics, vasoconstrictors,
preservatives, and other additives.

nerve block
 Sterilizing agents, skin-cleansing substances,
detergents, and certain preservatives (eg,
metabisulfite) all cause neurotoxicity and should be
carefully avoided when introduced into perineural
spaces.
 Because most regional anesthesia procedures involve
the percutaneous insertion of needles toward nerves,
the burden often lies with the anesthesiologist to prove
that damage was not caused as a result of improper
technique and unsafe practice.

nerve block
 Anesthesiologists have more information concerning
preoperative and intraoperative events than do most
neurologists.
 Symptoms and signs of compression of the spinal cord
must be dealt with urgently (within 6-8h).
 The anesthesiologist, neurologist, neurosurgeon, and
radiologist must work as a team to reach diagnosis
before serious permanent injury occurs.
 Electrodiagnostic and imaging techniques can often
help.

Surgical causes
1. Surgical retractors, a scalpel blade, or tension within the
surgical site may not have been mentioned to the
anesthesiologist.
2. Long-acting local anesthetics may have been injected by the
surgeon.
3. Compartment syndrome resulting from edema, or bleeding
around the wound caused by dressings or casts, can
compromise neural function.
4. Vascular injury during the surgery could result in nerve
injury.
5. Patient positioning must be reviewed to rule out direct
pressure otherwise attributed to a regional anaesthetic
mishap.

Anaesthetic causes
1. The details of anaesthesia management should
be thoroughly reviewed, especially if portions of
the anesthetic care were delivered by other
anaesthesiologists.
2. Drug choice, dose, and last time of
administration should be recorded.
3. Duration of nerve blockade should be noted; a
long duration of blockade can result in neural
injury.
4. High concentrations of agents probably increase
the risk of neural complications.

nerve block
5. Multiple nerve-blocking attempts can increase
the risk of injury.
6. The presence of paresthesia during needle
insertion and the subsequent injection of local
anaesthetic can be a warning sign indicating
neural injury.
7. The level of sedation must be appropriated
without compromising the ability to observe a
paresthesia.

nerve block
Diagnosis
 CT is best suited for evaluating bony abnormalities.
 MRI is ideally suited for the examination of soft-tissue
abnormalities, especially the spinal cord.
 For peripheral nerve, nerve plexus, and peripheral
nerve complications, imaging is less likely to be useful
for the demonstration of nerve injury.
 MRI may demonstrate the accumulation of blood and
edema fluid, which can lead to compartment
syndrome.

nerve block
 Nerve conduction studies test the function of large sensory
and motor nerve fibers. Evaluating nerve conduction can
reveal axonal loss or demyelination of the nerve; however,
nerve conduction is less useful in timing lesions when the
injury occurs.
 EMG is preferentially used for evaluating smaller motor
units. EMG can be useful for the diagnosis of axonal injury
and is also useful for quantitating the severity of the
neurologic injury and for identifying the actual site of
injury.
 EMG studies are typically recommended 2 to 3 weeks after
an injury.

nerve block
NEEDLE TRAUMA TO SURROUNDING STRUCTURES
 Vascular injury
 Pneumothorax
 Spinal cord injury
 Prevention of spinal cord injury
1. Perform it while awake.
2. Use of ultrasound
3. Use remote insertion sites.
4. Small gauge short needles

nerve block
Prevention of Pneumothorax
1. Extra care in tall, thin patients.
2. Right Pneumothorax for elevated cupola.
3. Avoid in severe impairment of pulmonary function.
4. Blocks should never be performed bilaterally.

Toxic effect of LA on nerve and
surrounding structures
NEURAL TOXICITY
 High concentrations of local anesthetics can
permanently damage neural tissue in some instances.
 Preservatives in local anesthetic drugs may also
damage nerves and other surrounding tissues.
 5% hyperbaric lidocaine for spinal anesthesia is linked
to the syndrome transient neurologic symptoms (TNS)

Myotoxicity
 Myotoxicity is a recognized complication of
intramuscular injections of local anesthetics.
 Local anesthetics are proposed to cause a pathologic
efflux of Ca++ from the sarcoplasmic reticulum,
resulting in contracture, cell destruction, and necrosis.
 In clinical practice, myotoxicity is largely unnoticed
except in ophthalmic regional anesthesia, as Diplopia
has been reported after retrobulbar blocks.

Phrenic nerve paresis
 Phrenic nerve paresis is common after supraclavicular
blocks, regardless of the technique used, yet patients
do not usually become symptomatic.
 Supraclavicular techniques may need to be avoided in
patients with advanced pulmonary disease.
 Bilateral supraclavicular techniques are absolutely
contraindicated.

HORNER SYNDROME
 Horner syndrome (ipsilateral, miosis, ptosis,
enophthalmos, loss of sweating) is frequently
observed after supraclavicular approaches to the
brachial plexus, although its incidence may be lower
when ultrasound is used to guide the supraclavicular
approach.

HOARSENESS
 Hoarseness may occur if the local anesthetic spreads
to the recurrent laryngeal nerve.
 Specific management is not required, as the symptoms
will abate as the anesthetic wears off.
 Persistent hoarseness should urge the clinician to
consider an alternative cause.

COMPLICATIONS OF NEURAXIAL
BLOCKS (EPIDURAL/SPINAL)
DIRECT NEEDLE TRAUMA
 As a needle or catheter is advanced into the epidural
space, direct trauma to the spinal cord, conus
medullaris, and spinal nerve roots can occur.
 Sensory loss and, less commonly, motor deficits occur
as a result of spinal cord trauma.
 Three well-known syndromes are associated with
damage to the spinal cord, roots, and coverings: cauda
equina syndrome, adhesive arachnoiditis, and anterior
spinal artery syndrome.

Prevention of direct needle trauma
 When performing an epidural in an awake, cooperative
adult, needle advancement should be halted if the
patient complains of pain.
 Pain is more commonly associated with extra-axial
lesions affecting the nerve roots or blood vessels that
are innervated by pain-mediating sensory neurons.
 In contrast, because there are no pain receptors within
the spinal cord (or the brain), intra-axial trauma may
be painless; this allows percutaneous cervical
cordotomy to be performed in awake patients.

 Electrical stimulation during epidural needle
advancement may provide an additional warning sign.
 Ischemic injuries are among the rarest complications
reported after regional anesthesia procedures;
Hypotension.
Anormal positioning.
Vascular disease.
Diabetes mellitus.
The clamping of major vessels.

Management of direct needle trauma
 Undiagnosed preexisting neurologic disorders.
 Ligation of nutrient spinal cord vessels during
abdominal or thoracic surgery.
 Injury to the femoral nerve during pelvic surgery.
 Injury to the lateral cutaneous nerve of the thigh
during retraction close to the inguinal ligament.
 Pressure on the fibular head leading to neurapraxia of
the lateral popliteal nerve.

 The lesion should be localized by taking the patient’s
history and by performing a thorough neurologic
examination.
 Bilateral symptoms associated with pain should alert
one to the possibility of neuraxial pathology.
 Injury at the nerve roots affects both posterior and
anterior rami.
 Preservation of sensation over the para-spinous
muscles suggests a more distal injury.

 Investigations should include blood cultures and
coagulation studies.
 Immediate MRI is the standard for evaluating
neuraxial lesions.
 EMG can be used to determine the site of injury and
the degree of axonal loss, although it may take up to 3
weeks for changes to appear on the electromyogram.
 It may be useful to perform this immediately upon
recognition of neural dysfunction to establish the
possibility of a pre-existing lesion.

HEMATOMA
Prevention
 The American Society of Regional Anesthesia has
released guidelines in response to this evolving
shift in medical practice; it is important to follow
these guidelines to minimize the risk of
hematoma.

Management
 Back pain with lower-limb weakness and sensory deficit
should alert the clinician to the presence of a central
compressing lesion.
 Bowel and bladder incontinence can be an associated
finding.
 Problem may be masked by the administration of local
anesthetic via an epidural catheter and the presence of a
urinary catheter.
 If MRI confirms the diagnosis, then rapid surgical
intervention within 6 to 8 hours is recommended.

INFECTION
 Epidural abscess presentation can be variable, but the
cardinal symptoms and signs involve back pain with
localized tenderness and fever that often develop days
after the puncture.
 Leukocytosis may occur several days or months after
needle and catheter insertion.
 Weakness may develop paraplegia if untreated.
 Meningitis may develop if the patient has endured a
lumbar puncture in this setting.

Prevention of infection
 Sound aseptic technique, monitoring of the infection
site, antibiotic prophylaxis, and bacterial filter use all
contribute to a lower incidence of epidural space
infections.
 Although both lidocaine and bupivacaine are
bactericidal in high concentration, this property is
likely not clinically significant at the concentrations
used in practice.
 The performance of neuraxial block should be avoided
where local infection exists at the needle entry site.

Management of Infection
 Prompt removal of the catheter is essential when
erythema and local discharge are present.
 Carefully assess any symptoms or signs of back pain.
 If any neural dysfunction occurs, a diagnosis must be
immediately made in order to evaluate infective
causes.
 Once a diagnosis of epidural abscess is made, a
combination of medical (antibiotic) and surgical
(incision and drainage) treatment may be needed.

TOTAL SPINAL ANESTHESIA
Prevention
 The subsequent use of small, incremental doses of
local anesthetics may reduce the risk of this
complication.
Management
 Resuscitation with endotracheal intubation,
mechanical ventilation, and vasopressor therapy is
frequently required, and recovery may take between 30
minutes and 6 hours.

SUBDURAL INJECTIONS OF LOCAL ANESTHETIC
DRUGS
 Clinically, the subdural injection of local anesthetic
drugs should be suspected when motor or sensory
changes do not follow the expected pattern.
 Subdural injections result in a very slow onset of motor
and sensory anesthesia and extensive and/or patchy
sensory blocking.

SYSTEMIC AND LOCAL TOXICITY
POSTDURAL PUNCTURE HEADACHE
 Bevel orientation is the most important factor.
 Needle gauge less than 25 .
 Blunt needles should be used for spinal anaesthesia.
Management
 Intrathecal placement of the epidural catheters after
accidental dural puncture in the obstetric setting is
common practice in some centers.

 Conservative measures, including bed rest and oral
hydration, remain popular therapies for PDPH, despite
no evidence to support them.
 Obstetric patients should be encouraged to mobilize
soon after delivery, so that PDPH, if present, can be
diagnosed and treated while yet in the hospital.
 A single oral dose of caffeine but prohibited in
pregnancy-induced hypertension.
 Sumatriptan is a serotonin type 1-d receptor agonist
and has been used for cluster headaches and migraine
and has been suggested as a treatment of PDPH.

 Cosyntropin, the synthetic form of ACTH hormone,
has been used to treat PDPH; this pharmaceutical is
thought to work by stimulating CSF production and β-
endorphin output.
The epidural blood patch
 The epidural blood patch (EBP) was introduced by
Gormley in 1960 and is known to be the most effective
treatment for PDPH.
 The success rate for a first epidural blood patch is 85%,
rising to 98% after a second patch.

 An assistant draws 15 to 20 mL of autologous blood
aseptically. The administration of blood should be
done at a rate of 1 mL/3 s. The end point of injection
occurs when the patient complains of back, neck, or
buttock pain.

Alternatives to the Epidural Blood Patch
 Epidural saline treatment has been used for PDPH, but
it is significantly less effective than EBP. Successful use
of prolonged saline infusion has been reported in
patients with failed EBP.
 Fibrin glue, a pooled plasma product, has been used to
treat CSF leak in cancer patients and in PDPH cases
after spinal anesthesia where 2 EBPs had failed.
 Dextran-40 has also been used to treat PDPH as it
undergoes delayed absorption from the epidural space
because of its high viscosity and molecular weight.

FAILURE OF SPINAL/EPIDURAL ANESTHESIA
 Easiness of pass of catheter into the epidural space.
 Catheters may become occluded with blood, or the
catheter may kink, take a unilateral course, break, or
become knotted, all of which can contribute to the
complete failure of epidural anesthesia.
 When epidural local anesthetic dosing for anesthesia
approaches the maximum safe limit without noticeable
analgesia, a failed epidural must be considered and
should prompt the clinician to pursue an alternative
course of anesthesia.

HYPOTENSION
 Significant hypotension may occur in obstetric patients but
it is uncommon in pediatric patients after the proper
administration of epidural analgesia.
 A high sympathetic single-shot caudal block to T6 caused
no significant changes in heart rate, cardiac index, or blood
pressure in children.
RESPIRATORY COMPLICATIONS
 End-tidal Pco2 and the tidal excursion of the abdomen
remained unchanged, whereas hypercapnic ventilatory
response decreased significantly.
 Lumbar and high thoracic region–induced epidurals do not
interfere with the ventilatory response to hypoxemia.

 Prevention of respiratory complications, do the
following:
 Avoid the use of high doses of opioids.
 Limit opioid dosages, especially in the intrathecal space.
 Avoid the concomitant use of parenteral opioids or
sedatives.
 Avoid or limit doses in the patient with advanced age (>60
years of age), sleep apnea, and other coexisting diseases.
 Use hydrophilic drugs (eg, morphine) with caution.

Management of respiratory complications:
 Treat mild respiratory depression with oxygen.
 If an infusion is used, then reduce the rate.
 Depending on the severity of respiratory
complications, consider ventilatory support, the
administration of narcotic antagonists, and the
discontinuation of the opioid infusion.

NAUSEA AND PRURITUS
To prevent and/or manage PONV and pruritus:
 Reduce the dose of neuraxial opioid.
 Use antihistamines, opioid antagonists (naloxone and
nalbuphine), propofol, nonsteroidal antiinflammatory
drugs (NSAIDs), and 5-HT3 receptor antagonists as
both preventative and therapeutic measures.
 Investigation into acupressure point P6 for the
prevention of PONV has revealed inconsistent
findings.

POSTOPERATIVE URINARY RETENTION
 Epidural use for postoperative pain management is
usually reserved for patients undergoing major
surgery, where urinary catheter placement may be
performed for reasons other than anticipated
postoperative urinary retention.
 A threshold of 600 mL has been suggested as a
diagnostic threshold.

BACKACHE
Prevention/Management Backache after epidural
placement
 Backache should not be ignored, as it can be a cardinal
symptom of a space-occupying lesion within the spinal
canal.
 Complications such as an epidural hematoma and
abscess, although rare, can have catastrophic
outcomes if unrecognized and untreated.

Regional anesthesia

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