Transcript Anesthesia for Orthopaedic Surgery

Dr abdollahi
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• Many orthopedic surgical procedures lend themselves to
the use of regional anesthesia (intraoperative anesthesia
and postoperative analgesia.
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• Anesthesia for orthopedic surgery requires an
understanding of special positioning requirements (risk of
peripheral nerve injury), appreciation of the possibility of
large intraoperative blood loss and techniques to limit the
impact of this occurrence (intraoperative hypotension,
salvage techniques).
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• The risk of venous thromboembolism (emphasizing the
need for the anesthesiologist to consider the interaction
of anticoagulants and antiplatelet drugs with anesthetic
drugs or techniques, especially regional anesthesia).
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Preoperative Assessment
.
• A brief neurologic examination with documentation of any
pre-existing deficits is recommended.
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Pre-Existing Medical Problems
• Coronary artery disease (perioperative β blockade should be
considered)
• Rheumatoid arthritis (steroid therapy, airway management)
Physical Examination
• Mouth opening or neck extension
• Evidence of infection and anatomic abnormalities at proposed
sites for introduction of regional anesthesia (peripheral
techniques may be acceptable if a regional technique is
contraindicated)
• Arthritic changes and limitations to positioning
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Choice of Anesthetic Technique
Advantages of Regional versus General Anesthesia for
Orthopaedic Surgical Procedures
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2.
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Improved postoperative analgesia
Decreased incidence of nausea and vomiting
Less respiratory and cardiac depression
Improved perfusion because of sympathetic nervous
system block
Decreased intraoperative blood loss
Decreased blood pressure
Blood flow redistribution to large caliber vessels
Locally decreased venous pressure
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Surgery to the Spine
Spinal Cord Injuries
• Spinal cord injuries must be considered in any patient
who has experienced trauma. (Cervical spine injuries are
associated with head and thoracic injuries, and lumbar
spine injuries are associated with abdominal injuries and
long bone fractures.)
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Tracheal Intubation
1.
2.
3.
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Airway management is critical because the most common
cause of death with acute cervical spinal cord injury is
respiratory failure.
All patients with severe trauma or head injuries should be
assumed to have an unstable cervical fracture until proven
otherwise radiographically.
Awake fiberoptic-assisted intubation may be necessary,
with general anesthesia induced only after voluntary upper
and lower extremity movement is confirmed.
In a truly emergent situation, oral intubation of the trachea
with direct laryngoscopy (minimal flexion or extension of
the neck) is the usual approach.
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Respiratory considerations
• Respiratory considerations include an inability to
cough and clear secretions, which may result in
atelectasis and infection.
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Cardiovascular considerations
• Cardiovascular considerations are based on loss of
sympathetic nervous system innervation (“spinal
shock”) below the level of spinal cord transection.
(Cardioaccelerator fiber [T1–T4] loss results in
bradycardia and possible absence of compensatory
tachycardia if blood loss occurs.)
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Succinylcholine-Induced Hyperkalemia
• Succinylcholine-Induced Hyperkalemia It is usually safe
to administer succinylcholine (Sch) within the first 48
hours after spinal cord injury. It should be avoided after
48 hours in all patients with spinal cord injuries.
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Temperature Control
• Loss of vasoconstriction below the level of spinal cord
transection causes patients to become poikilothermic.
(Body temperature should be maintained by increasing
ambient air temperature and warming intravenous [IV]
fluids and inhaled gases).
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Maintaining Spinal Cord Integrity
• .An important component of anesthetic management is
preservation of spinal cord blood flow. (Perfusion
pressure should be maintained, and extreme
hyperventilation of the lungs should be avoided.)
Neurophysiologic monitoring (somatosensory or motor
evoked potentials), a “wake-up test,” or both are used to
recognize neurologic ischemia before it becomes
irreversible.
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Autonomic Hyperreflexia
1. Occurs in 85% of patients with spinal cord transection
2.
3.
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above T5
Paroxysmal hypertension with bradycardia
(baroreceptor reflex)
Cardiac dysrhythmias
Cutaneous vasoconstriction below and vasodilation
above the level of transection
Precipitated by any noxious stimulus (distention of a
hollow viscus)
Treatment is removal of stimulus, deepening of
anesthesia, and administration of a vasodilator
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Scoliosis
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Pulmonary Considerations
Postoperative ventilation of the patient's lungs is likely to
be necessary if the vital capacity is below 40% of the
predicted value. Prolonged arterial hypoxemia,
hypercapnia, and pulmonary vascular constriction may
result in right ventricular hypertrophy and irreversible
pulmonary hypertension.
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Cardiovascular Considerations
• Prolonged alveolar hypoxia caused by hypoventilation
and ventilation/ perfusion mismatch eventually causes
irreversible vasoconstriction and pulmonary
hypertension.
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Surgical Approach and Positioning.
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The prone position is used for the posterior
approach to the spine. (The hazards of the prone
position, including brachial plexus stretch injury [the
head should be rotated toward the abducted arm
and the eyes taped closed], should be considered.
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•
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The anterior approach is achieved with the
patient in the lateral position, usually with the
convexity of the curve uppermost. Removal of a
rib may be necessary. A double-lumen
endotracheal tube is used to collapse the lung
on the operative side.
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•
A combined anterior and posterior approach in one or
two stages yields higher union rates but is associated
with increased morbidity, including blood loss and
nutritional deficits.
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Anesthetic Management
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Respiratory reserve is assessed by exercise
tolerance, vital capacity measurement, and arterial
blood gas analysis. Autologous blood donation is
often recommended (usually ≥4 U can be collected
in the month before surgery).
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There are specific anesthetic considerations for surgical
correction of scoliosis by spinal fusion and
instrumentation .
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Anesthetic Considerations for Surgical Correction of
Scoliosis
1. Management of the prone position
2. Hypothermia (long procedure and extensive exposed
3.
4.
5.
6.
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area)
Extensive blood and fluid losses
Maintenance of spinal cord integrity
Prevention and treatment of venous air embolism
Reduction of blood loss through hypotensive anesthetic
techniques
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•
Adequate hemodynamic monitoring and venous access
are essential in the management of patients undergoing
spinal fusion and instrumentation .
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Monitoring for Patients Undergoing Scoliosis Surgery
1. Cannulation of radial artery (direct blood pressure
measurement and assessment of blood gases)
2. Central venous catheter (evaluates blood and fluid
management and aspirate air if venous air embolism
occurs)
3. Pulmonary artery catheter (pulmonary hypertension)
4. Neurophysiologic monitoring (prompt diagnosis of
neurologic changes and early intervention)
Somatosensory evoked potentials Motor evoked
potentials Wake-up test
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Degenerative Vertebral Column Disease
• Spinal stenosis, spondylosis, and spondylolisthesis are
forms of degenerative vertebral column disease that may
lead to neurologic deficits necessitating surgical
intervention.
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Surgical Approach and Positioning
•
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Cervical laminectomy is most often performed with
patients in the prone position (Fig. 53-1).
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. Prone position with the patient's head turned and the
dependent ear and eye protected from pressure. Chest rolls
are in place, the arms are extended forward without
hyperextension, and the knees are flexed.
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•
•
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Fiberoptic-assisted intubation may be necessary in
patients with severely limited cervical movement.
The anterior approach places the surgical incision
(anterior border of the sternocleidomastoid muscle)
near critical structures (carotid artery, esophagus,
trachea [edema and recurrent nerve injury are
possible]).
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•
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The use of the sitting position for cervical
laminectomy allows a more blood-free surgical field
but introduces the risk of venous air embolism. The
incidence is less than for sitting posterior fossa
craniotomy, but the patient still needs to be
monitored with precordial Doppler.
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Anesthetic Management
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General anesthesia is most often selected for spinal
surgery because it ensures airway access and is
acceptable for prolonged operations. Patients
undergoing cervical laminectomy should be
assessed preoperatively for cervical range of motion
and the presence of neurologic symptoms during
flexion, extension, and rotation of the head. (Awake
fiberoptic intubation of the trachea may be
necessary.)
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•
Sch should be avoided if there is evidence of a
progressive neurologic deficit.
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Spinal Cord Monitoring
• Paraplegia is a feared complication of major spine
surgery. The incidence of neurologic injuries associated
with scoliosis correction is 1.2%. When patients awaken
with paraplegia, neurologic recovery is unlikely, although
immediate removal of instrumentation improves the
prognosis.
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• It is therefore essential that any intraoperative
compromise of spinal cord function be detected as early
as possible and reversed immediately. The two methods
for detecting intraoperative compromise of spinal cord
function are the “wake-up test” and neurophysiologic
monitoring.
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wake-up
• The wake-up test consists of intraoperative awakening of
patients after completion of spinal instrumentation.
Surgical anesthesia (often including opioids) and
neuromuscular blockers are allowed to dissipate, and the
patient is asked to move the hands and feet before
anesthesia is re-established. Recall may occur but is
rarely viewed as unpleasant, especially if the patient is
fully informed before surgery.
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Neurophysiologic monitoring
• Neurophysiologic monitoring (as an adjunct or an
alternative to the wake-up test) includes :
• Somatosensory evoked potentials (SSEPs)
(waveforms may be altered by volatile anesthetics,
hypotension, hypothermia, hypercarbia),
• Motor evoked potentials (MEPs) (neuromuscular
blocking drugs cannot be used),
• Electromyography.
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•
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SSEPs reflect the dorsal columns of the spinal cord
(proprioception and vibration) supplied by the
posterior spinal artery.
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•
•
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MEPs reflect the motor pathways and the portion of
the spinal cord supplied by the anterior spinal artery.
The combined use of SSEPs and MEPs may
increase the early detection of intraoperative spinal
cord ischemia.
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•
If both SSEPs and MEPs are to be monitored during
major spine surgery, one might consider providing
anesthesia with an ultrashort-acting opioid infusion with
a low dose of inhaled anesthetic and monitoring the
electroencephalogram to minimize the potential for
intraoperative awareness
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Blood Loss
• A combination of IV hypotensive agents and volatile
anesthetics is frequently used in an attempt to
decrease blood loss during surgery.
• Perioperative coagulopathy from dilution of
coagulation factors, platelets, or fibrinolysis may be
predicted from measurement of either the prothrombin
time or activated partial thromboplastin time.
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Visual Loss After Spine Surgery.
• Most cases are associated with complex instrumented
fusions often associated with prolonged intraoperative
hypotension, anemia, large intraoperative blood loss, and
prolonged surgery (also present in patients who do not
develop blindness). The American Society of
Anesthesiologists' Closed Claims Registry concludes that
patients at high risk for postoperative visual loss after
major spine surgery are those in whom blood loss is
1000 mL or greater or undergoing surgery lasting 6 hours
or longer.
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• The American Society of Anesthesiologists' Closed
Claims Registry concludes that patients at high risk for
postoperative visual loss after major spine surgery are
those in whom blood loss is 1000 mL or greater or
undergoing surgery lasting 6 hours or longer.
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Venous Air Embolus.
• Venous air embolism can occur in all positions used for
laminectomies because the operative site is above the
heart level. Presenting signs are usually unexplained
hypotension and an increase in the end-tidal nitrogen
concentration.
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Postoperative Care
Most patients' tracheas can be extubated
immediately after posterior spinal fusion operations
if the procedure was relatively uneventful and
preoperative vital capacity values were acceptable.
The presence of severe facial edema may prevent
prompt tracheal extubation.
2. Aggressive postoperative pulmonary care, including
incentive spirometry, is necessary to avoid
atelectasis and pneumonia.
3. Continued hemorrhage in the postoperative period
is a concern.
1.
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Epidural and Spinal Anesthesia After Major Spine
Surgery
• Postoperative anatomic changes make needle or
catheter placement more difficult after major spine
surgery .
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Changes After Major Spine Surgery That May Influence the
Ability to Perform Epidural or Spinal Anesthesia
1. Degenerative changes (spondylothesis below level of
fusion) that increase the chance of spinal cord ischemia
and neurologic complications with regional anesthesia
2. Ligamentum flavum injury from prior surgery results in
adhesions and possible obliteration of the epidural
space or interference with spread of local anesthetic
solution (“patchy block”)
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3.Increased incidence of accidental dural puncture if the
epidural space is altered by prior surgery (blood patch is
difficult to perform if needed)
4.Prior bone grafting or fusion may prevent midline
insertion of the needle
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• Spinal anesthesia may be a more reliable technique
than epidural anesthesia if a regional technique is
selected.
• The presence of postoperative spinal stenosis or other
degenerative changes in the spine or pre-existing
neurologic symptoms may preclude the use of regional
anesthesia in these patients.
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Surgery to the Upper Extremities
• Orthopaedic surgical procedures to the upper extremities
are well suited to regional anesthetic techniques .
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Regional Anesthetic Techniques for Upper
Extremity Surgery
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• Upper extremity peripheral nerve blocks may be used in
the treatment and prevention of reflex sympathetic
dystrophy. Continuous catheter techniques provide
postoperative analgesia and facilitate early limb
mobilization.
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• The patient should be examined preoperatively to
document any neurologic deficits because orthopaedic
surgical procedures often involve peripheral nerves with
pre-existing deficits (ulnar nerve transposition at the
elbow, carpal tunnel release of the median nerve at the
wrist) or may be adjacent to neural structures (total
shoulder arthroplasty or fractures of the proximal
humerus).
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• Improper surgical positioning, the use of a tourniquet,
and the use of constrictive casts or dressings may also
result in perioperative neurologic ischemia. Local
anesthetic selection should be based on the duration and
degree of sensory or motor block required. (Prolonged
anesthesia in the upper extremity in contrast to the lower
extremity is not a contraindication to hospital discharge.)
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Surgery to the Shoulder and Upper Arm
• A significant incidence of neurologic deficits in patients
undergoing this type of surgery demon-strates the
importance of clinical examination before regional
anesthetic techniques are performed.
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•
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Total shoulder arthroplasty may be associated with a
postoperative neurologic deficit (brachial plexus
injury) that is at the same level of the nerve trunks at
which an interscalene block is performed. It is
impossible to determine a surgical or anesthetic
cause. Most of these injuries represent neurapraxia
and resolve in 3 to 4 months.
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•
Radial nerve palsy is associated with humeral shaft
fractures, and axillary nerve injury is associated with
proximal humeral shaft fractures.
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Surgical Approach and Positioning
1.
2.
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Typically, the patient is flexed at the hips and
knees (“beach chair position”) and placed near
the edge of the operating table to allow
unrestricted access by the surgeon to the upper
extremity.
The head and neck are maintained in a neutral
position because excessive rotation or flexion of
the head away from the side of surgery may
result in stretch injury to the brachial plexus.
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Anesthetic Management.
• Surgery to the shoulder and humerus may be
performed under regional (interscalene or
supraclavicular brachial plexus block) or general
anesthesia. The ipsilateral diaphragmatic paresis and
25% loss of pulmonary function produced by
interscalene block mean that this block is
contraindicated in patients with severe pulmonary
disease.
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Surgery to the Elbow
• Surgical procedures to the distal humerus, elbow, and
forearm are suited to regional anesthetic techniques.
Supraclavicular block of the brachial plexus is more
reliable than the axillary approach (which may miss the
musculocutaneous nerve) but introduces the risk of
pneumothorax (typically manifests 6–12 hours after
hospital discharge such that postoperative chest
radiography may not be useful).
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surgery of the Wrist and Hand
• Brachial plexus block (axillary approach) is most commonly used
for surgical procedures of the forearm, wrist, and hand. The
interscalene approach is seldom used for wrist and hand
procedures because of possible incomplete block of the ulnar
nerve (15%–30% of patients), and the supraclavicular approach
introduces the risk of pneumothorax.
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•
IV regional anesthesia (“Bier block”) permits the use of a tourniquet
but has disadvantages of limited duration (90–120 minutes),
possible local anesthetic systemic toxicity, and rapid termination of
anesthesia (and postoperative analgesia) on tourniquet deflation.
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Continuous Brachial Plexus Anesthesia
• Catheters placed in the sheath surrounding the
brachial plexus permit continuous infusion of local
anesthetic solution. (Bupivacaine 0.125% prevents
vasospasm and improves circulation after limb
reimplantation or vascular repair.)
• Indwelling catheters may be left in place for 4 to 7
days after surgery.
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Surgery to the Lower Extremities
• Orthopaedic procedures to the lower extremity may be
performed under general or regional anesthesia,
although regional anesthesia may provide some unique
advantages .
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Lumbosacral Techniques for Major Lower Extremity
Surgery
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Surgery to the Hip
• Surgical Approach and Positioning. The lateral
decubitus position is frequently used to facilitate surgical
exposure for total hip arthroplasty, and a fracture table is
often used for repair of femur fractures. The patient must
be carefully monitored for hemodynamic changes during
positioning when under general or regional anesthesia.
(Adequate hydration and gradual movement minimize
blood pressure decreases.)
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• Care should be taken to pad and position the arms and
to avoid compression of the brachial plexus. (A “chest
roll” is placed caudad to the axilla to support the upper
part of the dependent thorax.)
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Anesthetic Technique
• Spinal or epidural anesthesia is well suited to procedures
involving the hip. Deliberate hypotension can also be
used with general anesthesia as a means of decreasing
surgical blood loss.
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Total Knee Arthroplasty (TKA)
• Patients undergoing TKA experience significant
postoperative pain, which impedes physical therapy
and rehabilitation.
• Regional anesthetic techniques that can be used for
surgical procedures on the knee include epidural,
spinal, and peripheral leg blocks. Spinal anesthesia is
often selected, but an advantage of a continuous
epidural is postoperative pain management.
(Aggressive postoperative regional analgesic
techniques for 48–72 hours shorten the rehabilitation
period more than systemic opioids.)
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• Patients undergoing amputation of a lower limb often
benefit from the use of regional anesthesia, although
adequate sedation is imperative.
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Postoperative Analgesia after Major Joint
Replacement.
• Pain after total joint replacement, particularly total knee
replacement, is severe. Single-dose and continuous
peripheral nerve techniques that block the lumbar plexus
(femoral nerve block) with or without sciatic nerve block
provide excellent postoperative analgesia.
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Knee Arthroscopy and Anterior Cruciate
Ligament (ACL) Repair
• Diagnostic knee arthroscopy may be performed under
local anesthesia with sedation. (A single dose or
continuous lower extremity block is not warranted in most
patients.) ACL repair requires
• postoperative analgesia (femoral nerve blocks should be
considered).
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• Intra-articular injection of local anesthetics (bupivacaine),
opioids (morphine), or both has become routine for
perioperative management after arthroscopic knee
surgery.
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Surgery to the Ankle and Foot
• The selection of a regional technique is based on the
surgical site, use of a tourniquet (use of a high
tourniquet for longer than 15–20 minutes necessitates
a neuraxial or general anesthetic), and need for
postoperative analgesia.
• Peripheral nerve blocks (femoral and sciatic nerve)
provide acceptable anesthesia for surgery on the foot
and ankle.
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• Microvascular Surgery
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Anesthetic Considerations for Microvascular
Surgery for Limb Replantation
1.
2.
3.
4.
5.
6.
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Maintain blood flow through microvascular anastomoses
(critical for graft viability).
Prevent hypothermia (increase temperature of operating
room to 21°C; warm IV solutions and inhaled gases).
Maintain perfusion pressure.
Avoid vasopressors.
Use vasodilators (volatile anesthetics, nitroprusside) and
sympathetic nervous system block (regional anesthesia).
Consider normovolemic hemodilution.
Administer antithrombotics (heparin) with or without
fibrinolytics (low-molecular-weight dextran).
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•
•
•
•
•
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7.Remember positioning considerations associated with
long surgical procedures.
8.Replace blood and fluid losses.
9.Consider the choice of anesthesia (often a
combination of regional and general anesthesia)
10.Sympathectomy is helpful, but the long duration of
surgery may limit use of single-shot techniques
(another option is a continuous technique)
11.Ensure airway access and patient immobility.
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Pediatric Orthopaedic Surgery
• Regional anesthetic techniques are adaptable to pediatric
patients, especially in those older than 7 years of age.
• IV regional anesthesia is particularly useful in pediatric
patients for minor procedures such as closed reduction of
forearm fractures.
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• The use of local anesthetic creams minimizes patient
discomfort during placement of an IV catheter.
• The size of the upper arm often precludes the use of a
double tourniquet in pediatric patients, thus limiting the
duration of the surgical procedure to 45 to 60 minutes
(tourniquet pain typically develops by this time).
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Other Considerations
• Anesthesia for Nonsurgical “Closed” Orthopaedic
Procedures. Some minor procedures (cast and dressing
changes in pediatric patients, pin removal) require only
light sedation, but procedures involving bone and joint
manipulation (hip and shoulder relocation, closed
reduction of fractures) usually require a general or
regional anesthetic.
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Tourniquets
• Opinions differ as to the pressure required in
tourniquets to prevent bleeding (usually 100 mm Hg
above patient's systolic blood pressure for the leg and
50 mm Hg above systolic blood pressure for the arm).
Before the tourniquet is inflated, the limb should be
elevated for about 1 minute and tightly wrapped with
an elastic bandage distally to proximally. Oozing
despite tourniquet inflation is most likely caused by
intramedullary blood flow in long bones.
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• The duration of safe tourniquet inflation is unknown
(1–2 hours is not associated with irreversible
changes). Five minutes of intermittent perfusion
between 1 and 2 hours may allow more extended use.
• Transient systemic metabolic acidosis and increased
PaCO2 (1–8 mm Hg) may occur after tourniquet
deflation.
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• Tourniquet pain despite adequate operative
anesthesia typically appears after about 45 minutes
(may reflect more rapid recovery of C fibers as the
block wanes). During surgery, this pain is managed
with opioids and hypnotics
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Fat Embolus Syndrome
• Patients at risk include those with multiple traumatic
injuries and surgery involving long bone fractures,
intramedullary instrumentation or cementing, or total
knee surgery. The incidence of fat embolism syndrome
in isolated long bone fractures is 3% to 4%, and the
mortality rate is 10% to 20%.
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• Clinical and laboratory signs usually occur 12 to 40
hours after injury and may range from mild dyspnea to
coma .
• Treatment includes early stabilization of fractures and
support of oxygenation. Steroid therapy may be
instituted
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Criteria for Diagnosis of Fat Embolism
Syndrome
•
1.
2.
3.
4.
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MAJOR :
Axillary or subconjunctival petechiae
Hypoxemia (PaO2< 60 mm Hg)
CNS depression (disproportionate to hypoxemia)
Pulmonary edema
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Criteria for Diagnosis of Fat Embolism
Syndrome
• MINOR:
1. Tachycardia (>100 bpm)
2.
3.
4.
5.
6.
7.
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Hyperthermia
Retinal fat emboli
Urinary fat globules
Decreased platelets
Increased ESR
DIC
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Methyl Methacrylate
• Insertion of this cement may be associated with
hypotension, which has been attributed to absorption of
the volatile monomer of methyl methacrylate or
embolization of air (nitrous oxide should be discontinued
before cement is placed) and bone marrow during
femoral reaming.
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• Adequate hydration and maximizing oxygenation
minimize the hypotension and arterial hypoxemia that
may accompany cementing of the prosthesis.
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• Venous thromboembolism is a major cause of death after
surgery or trauma to the lower extremities. Without
prophylaxis, 40% to 80% of orthopaedic patients develop
venous thrombosis. (The incidence of fatal pulmonary
embolism is highest in patients who have undergone
surgery for hip fracture.)
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• Antithrombotic prophylaxis is based on identification of
risk factors .
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Antithrombotic Regimens to Prevent Thromboembolism in Orthopedic
Surgical Patients
• Hip and Knee Arthroplasty and Hip Fracture Surgery
• LMWH* started 12 hours before surgery or 12 to 24 hours after
surgery or 4 to 6 hours after surgery at half the usual dose and then
increasing to the usual high-risk dose the following day.
• Fondaparinux (2.5 mg started 6 to 8 hours after surgery)
• Adjusted-dose warfarin started preoperatively or the evening after
surgery (INR target, 2.5; range, 2.0–3.0)
• Intermittent pneumatic compression is an alternative option to
anticoagulant prophylaxis in patients undergoing total knee (but not
hip) replacement.
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• Spinal Cord Injury
• LMWH after primary hemostasis is evident
• Intermittent pneumatic compression is an alternative
when anticoagulation is contraindicated early after
surgery.
• During the rehabilitation phase, conversion to adjusted-
dose warfarin (INR target, 2.5; range, 2.0–3.0).
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• Elective Spine Surgery
• Routine use of thromboprophylaxis, apart from early and
persistent mobilization, is not recommended.
• Knee Arthroscopy
• Routine use of thromboprophylaxis, apart from early and
persistent mobilization, is not recommended.
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• Several studies show a deceased incidence of deep vein
thrombosis (DVT) and pulmonary embolism in patients
undergoing hip surgery and knee surgery under epidural
and spinal anesthesia .
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Possible Explanations for Decreased Incidence of Deep Vein
Thrombosis in Patients Receiving Regional Anesthesia
• Rheologic changes resulting in hyperkinetic lower
•
•
•
•
extremity blood flow and associated decrease in venous
stasis and thrombus formation
Beneficial circulatory effects from epinephrine added to
local anesthetic solution
Altered coagulation and fibrinolytic responses to surgery
under neural blockade, resulting in decreased tendency
for blood to clot
Absence of positive pressure ventilation and its effects on
circulation
Direct local anesthetic effects (decreased platelet
aggregation)
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• Despite perceived advantages of neuraxial techniques
for hip and knee surgery (including a decreased
incidence of DVT), patients receiving perioperative
anticoagulants and antiplatelet medications are often not
considered candidates for spinal or epidural anesthesia
because of the risk of neurologic deficit from a spinal or
epidural hematoma .
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Neuraxial Anesthesia and Analgesia in Orthopedic Patients
Receiving Antithrombotic Therapy
• Low-Molecular-Weight Heparin
• Needle placement should occur 10 to 12 hours after a
dose.
• Indwelling neuraxial catheters are allowed with once• daily (but not twice-daily) dosing of LMWH.
• It is optimal to place and remove indwelling catheters in
the morning and administer LMWH in the evening to
allow normalization of hemostasis to occur before
catheter manipulation.
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Warfarin
• Adequate levels of all vitamin K–dependent factors
should be present during catheter placement and
removal.
• Patients chronically on warfarin should have a normal
INR before performance of the regional technique.
• PT and INR should be monitored daily.
• The catheter should be removed when INR <1.5.
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Fondaparinux
• Neuraxial techniques are not advised in patients who are
anticipated to receive fondaparinux.
.
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Nonsteroidal Anti-Inflammatory Drugs
• No significant risk of regional anesthesia-related
•
bleeding is associated with aspirin-type drugs.
• For patients receiving warfarin or LMWH, the combined
anticoagulant and antiplatelet effects may increase the
risk of perioperative bleeding.
• Other medications affecting platelet function
(thienopyridine derivatives and glycoprotein IIb/IIIa
platelet receptor inhibitors) should be avoided.
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• The patient should be closely monitored in the
perioperative period for signs of paralysis. If a spinal
hematoma is suspected, the treatment is immediate
decompressive laminectomy. (Recovery of neurologic
function is unlikely if >10–12 hours elapse.)
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