2. FACTORS TO CONSIDER FOR ORTHOPEDIC ANESTHESIA
a. Age
b. Duration of surgery
c. Type of surgery
e. Positioning
3. PREOPERATIVE ASSESSMENT
a. Essential for formulation of a plan.
b. Evaluate coexisting disease states.
c. Potential airway difficulties.
d. Positioning considerations.
4.
PNEUMATIC TOURNIQUET
a. Goal of orthopedic surgeons is to have a bloodless
field.
b. This can be accomplished with the use of a tourniquet.
i. Can be used for both upper and lower extremities.
ii. Tourniquets has it’s advantages of providing a
bloodless field and reduction of operative time, but also has it’s risks à hemodynamic
changes, pain, metabolic alterations, arterial thromboembolism, pulmonary
embolism
c. Pneumatic cuffs
i. Consists of an inflatable cuff, cuff tubing, pressure
gauge and pressure regulator.
ii. The pneumatic cuff must have at least 3-6 inches of
overlap in comparison to the sphygmomanometer.
d. Care
i. Anesthetist should insure that there is proper padding
underneath the cuff to avoid wrinkling of the cuff[WU5] .
ii. The cuff over lay should be in an area that avoids
neurovascular bundles (e.g., Brachial plexus).
iii. If the cuff is on the humorus then the over lay should
rest on the lateral aspect of the arm.
e. Inflation pressures.
i. Are determined by the patients initial systolic blood
pressure on induction.
ii. Inflation pressure for adequate hemostats is
90-100mmhg above the initial systolic pressure.
iii. Cuff pressures should not exceed 300 and 500mmhg for
the upper extremity and lower extremity respectively.
f. Exsanguinations of the extremity
i. Occurs prior to cuff inflation
ii. Extremity is elevated, and eshmar bandage applied.
i. Tourniquet pain
1. Due to ischemia of the nerve fibers due to compression
of intraneural blood vessels.
2. Discomfort is usually under the cuff and described as
a burning sensation.
3. Discomfort is usually reported around 45-60 minutes of
tourniquet time.
ii. Causes
2. Researchers have identified the nerve fibers
associated with tourniquet pain to be the nerve cell fibers.
3. Burning and aching is thought be associated with
small, slow conducting unmyelinated C-fibers.
4. Tingling, pin prick sensations seen after cuff
deflation is thought to be related to the larger faster myelinated A-delta
fibers.
iii. Postopertative tourniquet paresthesia
1. Caused by excessive tourniquet pressure, in
appropriate size and prolonged tourniquet time.
h. SIDE EFFECTS OF TOURNIQUET DEFLATION
i. Common effects seen with tourniquet release and
reperfusion is:
1. Increased serum K, bicarbonate, and CO2 levels.
2. Decreased PH, core temperature, and arterial O2 pp.
i.
TOURNIQUET TIME
i. Ischemic changes are thought not to occur with
tourniquet time less than 2 hours.
ii. Permanent nerve damage has been associated with times
greater than 4 hrs.
iii. Serum parameters return to normal after 20 minutes
with a T-time of less than one hour., and[WU10] 40 minutes with T-time of 3 hours.
iv. Muscle strength took as long as one week with a T-time
of 3 hours.
5.
POSITIONING FOR ORTHOPEDIC SURGERY
a. There are 3 main positions
i. Lateral
ii. Prone
iii. Supine
b. Patient positioning is crucial
i. Allows optimal exposure
ii. Provide adequate monitoring
iii. Minimize physiologic compromise.
6.
HIP SURGERY
a. Fracture of the hip
b. Total hip replacement (arthroplasty)
c. Hip dislocation (closed reduction)
7.
ARTHROSCOPY
a. Arthroscopy was first described and demonstrated
in1918 and introduced in the U.S in 1926[WU11] .
b. Purpose for arthroscopy
i. Get diagnosis of orthopedic malady
ii. Removal of lose body or ligament repair.
c. Types of procedures
i. Knee, shoulders, hips, elbow wrist and ankles.
d. Anesthetic considerations:
i. General, regional, combined.
ii. Choice is determined by type of procedure and pain
associated with the malady.
e. Positioning
i. Dependent on the Procedure
f. Pressurized irrigation solution
i. The Nurse anesthetist should take note of the volume
of irrigation in to irrigation out.
ii. The bag of solution should be 3-4 feet above the
operative limb.
iii. The pressure is 90mmhg for hanging device, and 60-80
mmhg for mechanical pumps.
iv. Bags come in 3-5L
v. Salt poor solutions are used and the patient may
develop hyponatremia, and signs of CHF with too much absorption of irrigation
fluid.
8.
FRACTURE OF THE HIP
a. Most of the patients presented with hip fractures are
frail and elderly.
b. Coexisting diseases may also be present: such as,
coronary artery disease, HTN and diabetes.
c. These patients are frequently dehydrated and
malnourished.
d. Occult blood loss may be present depending on the type
of fracture.
i. E.g., subcapital are associated with less blood loss
than extracapsular.
e. COMPLICATIONS:
1. Can occur within 72hrs following long bone fracture.
(or pelvic fracture)
2. Have a high mortality rate of 10-20%.
3. Patients often go into ARDS.
4. Symptoms includes: Confusion, dyspnea,
hypoxia and petechiae. (triad)
ii. Theory behind fat emboli.
1. Fat globules are released from the destruction of fat
cells in fractured bone
2. These globules are released and enter into the
circulation through tears in medullary vessels.
iii. Diagnosis of fat emboli.
1. Truncal and upper extremity petechiae (chest, upper extremities, axillae,
conjunctiva)
a. Petechiae result from the occlusion of dermal
capillaries by fat globules, leading to extravasation of erythrocytes; no
abnormalities of platelet function have been documented. The rash resolves in
five to seven days.
2. Coagulation abnormalities (thrombocytopenia, prolonged clotting times)
3. Decreased ETCO2, and O2 sat
4. Increased arterial CO2, or rise in pulmonary artery
pressure.
5. Ischemic-appearing
ST-segment changes and R-sided heart strain
iv. Treatment of fat emboli.
1. Volume resuscitation with albumin- Binds with fatty
acids and may minimize extent of lung injury.
2. Early stabilization of fracture decreases the
incidence.
3. Supportive consists of oxygen therapy with CPAP.
4. High dose hydrocortisone has been shown to be beneficial
with cerebral edema.
v. Intra-op management.
1. Regional vs general
2. Regional technique – studies have shown a lower
mortality rate than general.
3. Studies have shown a decrease in thromboembolic complications.
4. This may be due to a decrease in platelet activity, an
increase in lower extremity blood flow and decrease in postoperative factor
VIII.
vi. Continuous epidural technique offers postoperative
pain management.
vii. Hypobaric technique may be used so that the patient
doesn’t have to lie on the operative side.
9.
TOTAL HIP ARTHROPLASTY
a. Preoperative considerations:
ii. Osteoarthritis- is a degenerative disease affecting
the articular surface of many joints[WU16] .
iii. Rheumatoid arthritis- immune mediated joint
destruction. Patients with rheumatoid arthritis may also have systemic
involvement affecting the heart, and lungs[WU17] .
b. Anesthetic considerations:
i. osteoarthritis may involve the spine and neck, making
difficulty with intubation.
c. Patients with Rheumatoid arthritis may have
involvement of the C-spine.
d. If the arthritis is severe enough for steroid
treatment, than a c-spine film should be obtained.
e. If an atlantoaxial instability is > 5mm then a
fiberoptic intubation should be considered.
f. Hoarseness and respiratory stridor may indicate
cricoarytenoid arthritis
10.
BILATERAL HIP REPLACEMENT
a. May be performed safely
b. Usually requires CSE.
c. PAWP may be placed to monitor any increase in
pulmonary artery pressure after the first side is done[WU18] .
11.
HIP REVISIONS
a. Are associated with increased blood loss.
c. Controlled hypotension – can decrease intraop bleeding
d. Aprotinin or
human erythropoietin are methods to reduce bleeding
12.
HIP DISLOCATION
a. A closed reduction of the hip can be performed.
b. Increased risk (2%) with joint replacement, 20%
increase with revisions. – less force is
required to dislocate a prosthetic hip
c. Extreme caution with positioning for subsequent
surgical procedures:
i. Avoid extreme hip flexion >90 degrees.
ii. Internal rotation > 20 degrees.
iii. Adduction > 20 degrees.
d. Closed reductions are done under G.A via mask with
succinylcholine.
13. KNEE SURGERIES
a.
KNEE ARTHROSCOPY
i. Typically done on young healthy, and athletic
patients.
2. Goal is to have the patient up and ambulatory, free of
pain.
ii. Intra-op tourniquet.
1. Facilitates blood less field.
b. COMPLICATIONS OF KNEE SURGERIES
i. Are associated with complications which includes:
1. Metabolic alterations (acidosis)
2. Chest pain
3. Emboli
4. Tourniquet pain.
ii. Prolonged T-time >2hrs are associated with
peripheral nerve injury.
iii. The patient may have fluid shifts.
iv. Tourniquet pain.
v. Hyper/hypotension.
vi. Increased Etco2 due to wash out of metabolic wastes.
vii. Arrhythmias.
viii. Severe aching and burning sensation with tourniquet
pain.
ix. Causes:
1. Un-myelonated C-fibers are harder to block with local
anesthetics and may play a role in T-pain.
x. Treatment
1. If severe analgesics can be administered.
2. Immediate cuff deflation. Caution is taken to control
hypotension.
c. POST OP PAIN RELIEF
i. Avoid large doses of opioids.
ii. Remember the goal is early ambulation.
iii. Intra-articular bupivicaine 0.25% (20-30cc).
14.
TOTAL KNEE ARTHROPLASTY
a. Patient presentation is similar to a total hip
replacement.
c. Have coexisting diseases.
d. May be on anticoagulation therapy.
e. Elderly.
f. INTRAOPERATIVE CONSIDERATIONS
i. Duration of surgery is less than that of a total hip
replacement.
ii. Blood loss is limited to the use of a tourniquet.
iii. Patients may have a drop in hemoglobin in the post op
period from hidden blood loss.
iv. Blood loss post op can range from 400-1700cc.
1. CSE with Bupivicaine 0.5% 10-17.5mg.
vi. If epidural fails a femoral nerve block may be done in
the post op period.
vii. Complications r/t TKA:
1. Cement implantation syndrome.
2. Emboli
3. Tourniquet pain, and peripheral nerve injury.
4. Hypotension with cuff deflation.
15.
BONE CEMENT IMPLANTATION SYNDROME
a. Hypoxia
b. Hypotension
c. Dysrrhythmias
d. Pulmonary HTN
e. Decreased cardiac output.
f. Strategies to minimize the effects:
i. Maintain euvolemic
ii. Increase O2 prior to cementing
iii. Creating a vent hole in the distal femur to minimize
pressure.
iv. Un-cemented components.
i. Mixing polymerized MMA (PMMA) powder with liquid MMA
monomer causes polymerization and cross-linking of polymer chains.
ii. This exothermic reaction leads to cement hardening and
expansion against prosthetic components.
h. The resultant intramedullary hypertension[WU26] can cause embolization of fat, bone
marrow, cement, and air into the femoral venous channels
i.
The residual methylmethacrylate
monomer can also cause vasodilatation and a decrease in systemic vascular
resistance, thought to be the cause for the transient hypotension often seen
with cement insertion.
j.
The release of
tissue thromboplastin may trigger:
i. platelet aggregation,
ii. microthrombus formation in the lungs,
iii. cardiovascular instability as a result of circulation
of vasoactive substances[WU27] .
k. Clinical Manifestations of bone cement implantation
syndrome include:
i. Hypoxia (increased pulmonary shunt)
ii. Hypotension
iii. Dysrhythmias (including heart block and sinus arrest)
iv. Pulmonary hypertension (incr pulmonary vascular
resistance)
l.
Strategies to
minimize the effects of this complications include:
i. Increase inspired oxygen concentration prior to
cementing
ii. Maintaining normovolemia, monitor blood loss
carefully, monitor CVP
iv. Use uncemented femoral component
16.
SPINAL SURGERY
a. Usually performed for symptomatic nerve root
compression or cord compression.
b. Compression may occur d/t disc herniation, or
osteophytes (spondylosis) into the spinal canal.
c. Scoliosis of the spine.
d. Decompression or stabilization following trauma.
e. TYPES OF SPINAL SURGERIES
i. Anterior cervical fusion
ii. Posterior cervical fusion
iii. A/P Thoracic decompression and fusion
iv. Lumbar decompression and fusion
f. Anesthetic considerations
i. Anything above L3 may require evoked potential
monitoring
g. PREOPERATIVE CONSIDERATIONS
i. Existing ventilatory impairment.
ii. Anatomic abnormality of the back and neck compromising
airway management.
1. E.g., unstable neck and securing the airway.
2. Consider an awake fiberoptic, nasal intubation.
iii. Identify preexisting deficits.
1. E.g., weakness or numbness.
h. INTRAOPERATIVE MANAGEMENT
i. Positioning
1. Prone considerations:
a. Head position.
b. Retinal ischemia.
c. Pressure necrosis.
d. Decreased ventilation if abdomen is compressed[WU30] .
e. Arm position.
f. Limited access.
2. Supine position:
a. Cervical surgeries can be performed with traction to
protect the trachea, esophagus and recurrent laryngeal nerves.
3. Transthoracic approach:
a. May be required for anterior thoracic spine.
b. The patient may require a double lumen tube with one
lung ventilation.
ii. Placement of instrumentation:
1. De-rotational or and pedicle screws.
2. You need to be able to differentiate between spinal
cord injury and excessive distraction.
i.
MONITORING FOR SPINAL CORD INJURY
i. Wake up test:
1. A short acting opioid and muscle relaxant is used.
2. The anesthetic is d/c’d 30-45min prior to the wake up.
3. The patient is allowed to wake up and monitoring of
function is performed.
4. The patients are asked to move b/l hands and feet.
5. True function may not be fully returned d/t the
anesthetic.
6. Accidental dislodging of the endotracheal tube.
7. The patient has to be completely cooperative.
8. Rods and screws may become dislodged.
ii. SSEP:
1. Avoids intraop awakening.
2. SSEP involves the dorsal column pathways of sensory
and proprioception, motor function may still be affected.
iii. Evoked potentials will monitor motor, visual (CN II),
brainstem and auditory (CN VIII) senses.
1. Resection of spinal tumors
2. Corrective surgery (Scoliosis).
3. Cranial tumors
iv. How SSEP are elicited
1. SSEP are elicited by electrical stimulation of the
ulnar, tibial and radial nerves.
2. SSEP monitors the integrity of the posterior (Dorsal)
spinal cord where sensory tracts of the dorsal-lemniscal system are located
(PDS).
3. Electrode placement
a. Electrodes are placed between the ears on the scalp.
v. Anesthetic effects on SSEP
1. NMB agents will not have any effect on sensory monitoring[WU31] .
2. Inhalational agents will have an effect on sensory
monitoring.
3. Agents must be at 0.5 MAC if used.
4. With a lumbar decompression and fusion inhalational
agents may be used, but NMB may be omitted.
vi. Physiologic factors affecting SSEP
1. Hypothermia
a. Has the greatest effect. It will increase the latency
and decrease the amplitude of the signal.
b. Latency increases by 1ms for each 1 degree C decrease
in temp.
2. Decreased MAP
3. Hypoxia
a. Decreases SSEP amplitude
4. ETCO2
a. < 25mmhg
will increase the latency of the signal.
vii. Monitoring for spinal cord injury
1. In SSEP you want to look at the amplitude and the
latency of the signal, and know what the effects anesthesia has on these
signal.
2. Inhalational anesthetics will cause a decrease in the
amplitude (intensity) of the signal, and an increased latency (Time it takes
from signal to the next).
4. Motor evoked potentials
a. Motor evoked potentials (MEP) are recorded from
muscles following direct stimulation of exposed motor cortex, or transcranial
stimulation of motor cortex, either magnetic or electrical.
5. Somatosensory evoked potentials (SEPs)
a. are generated by stimulation of afferent peripheral
nerve fibers by either physiological or electrical means.
viii. Anesthetic Technique
1. Inhalational anesthetics
a. Decreases frequency and increased latency of signals.
b. No inhalational or less than 0.5mac
c. No Nitrous
a. MEP no MR
b. NO MR for SSEP
3. Total Intravenous anesthesia (TIVA)
b. Sufentanyl 0.15-0.25mcg/kg/hr
4. IVs
a. 2 large bore IV.
b. 16g & 18g
Extra M&M ch. 40:
DVT
& PE:
Highest
risk are those undergoing hip surgery and knee reconstruction
Pathyphys
mechanisms: venous stasis & a hypercoagulable state d/t localized and
systemic inflammatory responses to surgery
Prophylactic
anticoagulation and use of intermittent pneumatic leg compression (IPC) devices
significantly decreases incidence of DVT and PE
Neuraxial
anesthesia alone or when combined with g/a may reduce thromboembolic
complications by several mechanisms including sympathectomy-induced increases
in lower-extremity venous blood flow, systemic anti-inflammatory effects of LA,
decr platelet reactivity, attenuated postop incr in factor VIII and von
Willebrand factor, attenuated postoperative decreases in antithrombin III, and
alterations in stress hormone release
[WU1]Epidurals
not used for hip replacement post op – don’t have pain issues like knee
replacement or b/l hip replacement
[WU2]M&M:
Common orthopedic challenges:
1.
Long bone fractures predispose to fat embolism
syndrome
2.
High risk for venous thromboembolism esp
following pelvic, hip and knee operations
3.
Bone cement during arthroplasties can cause
hemodynamic instability
4.
Risks
associated with limb tourniquets
5.
Regional anesthesia techniques decr incidence of
thromboembolic complications, provide postop analgesia and promote early rehab
and d/c
[WU3]Spinal
doses:
Marcaine 10-17.5 mg (some sources 20 mg)
Tetracaine ___
Regional has better muscle relaxation – optimal
operating conditions and less incidence of blood clotting post op – less
hemodynamic compromise associated with intubation and VAAs
G/A set up must be back up. Spinal might wear off if
case is long. Can insert LMA or ETT
*epi typically does not prolong a spinal
**there is a difference btwn infiltration doses and
spinal doses
[WU4]Contraindicated
for regional technique
If history does not warrant coags, do not routinely do
PT/PTT. If there is no time to wait for
labs, do general anesthesia
[WU5]Need
to keep track of tourniquet time and mmHg
With AS, hypotension is harder to control with regional
vs. giving VAA during G/A – less likely to do regional on someone with AS
Max time is 2 hrs – prolonged inflation routinely leads
to transient muscle dysfunction and associated with permanent peripheral nerve
injury or even rhabdomyolysis
Deflate for 15 min and reinflate
[WU6]Other
complications:
Nerve damage
Incr CO2 from lactic acid
Hypotension during release
Compartment syndrome
Clotting issues – DVTs and microemboli; subclinical PE
Latex rxn
CI in pts with calcific arterial disease
[WU7]Tourniquet
pain gradually becomes so severe over time that pts may require substantial
supplemental analgesia or even g/a despite a regional block that is adequate
for surgical incision.
During g/a, tourniquet pain is manifested as gradually
incr MAP 1 hr after inflation. Signs of progressive sympathetic activation
include marked Incr HR and BP and diaphoresis
Tx: opioid
[WU10]Cuff
deflation immediately relieves sensation of tourniquet pain and its HTN. Can be accompanied by a significant fall in
CVP and arterial BP. HR incr and core
temp decr. Washout of accumulated
metabolic wastes in ischemic extremity incr PaCO2, ETCO2, and serum lactate and
K levels. These metabolic alterations
can cause an incr in minute ventilation in spontaneously breathing pt and
sometimes dysrhythmias
Blood reoxygenation has been demonstrated to worsen
ischemic tissue injury d/t formation of lipid peroxides – can be attenuated by
propofol
[WU12]Usually
associated with long-bone fracture
Can also be seen following cardiopulm resuscitation,
parental feeding with lipid infusion and liposuction
[WU13]Alternative
theory- fat globules are chylomicrons resulting from the aggregation of
circulating free fatty acids caused by changes in fatty acid metabolism
[WU14]Leading
to release of vasoactive amines and prostaglandins and development of ARDS
Neuro manifestations: agitation, confusion, stupor,
coma – probably represent capillary damage to the cerebral circulation and
cerebral edema and may be exacerbated by hypoxia
[WU15]Neck
stability; difficult intubation à
cricoarytenoid arthritis (hoarseness or inspiratory stridor may signal a
narrowing of glottis opening)
Gentle intubation to avoid nerve root compression or
nucleus pulposus protrusion
[WU17]Chronic
and progressive inflammation of synovial membranes; typically involves multiple
joints, including small joints of hands, wrists and feet
Atlantoaxial subluxation – may need to do awake
fiberoptic technique
TMJ involvement – may need nasal fiberoptic
Usually tx with NSAIDS à inhibition of synthesis of prostaglandins y cyclooxygenase (COX) enzyme of which there
are 2 isoforms (COX-1 and COX-2) most of side effects are d/t COX-1 inhibition;
pain and anti-inflammatory are COX-2
[WU18]Rarely
done
Reliably signals embolization by a rise in PVR, PAP,
unchanged PAWP and falling CO
Normal PVR is 200 dynes/s/cm-5
[WU19]Lose
500-1000cc blood usually will give blood even if they don’t need it or not a
great blood loss
[WU20]Extensive
surgery
Incr blood loss – 5 liters
Be vigilent with monitoring what is coming out
Cell saver: pt must lose 625 ml to give pt back blood
[WU21]g/a
with LMA
opioids: fentanyl
ketorolac
antiemetic
some centers use neuraxial anesthesia. Alternative regional techniques include a 3
in 1 femoral nerve and lateral femoral cutaneous nerve blocks (w/ or w/o
sciatic nerve block), psoas compartment block, and local infiltration
[WU24]how
to dose through epidural:
-test dose 3 ml lidocaine with epi
-give lidocaine if not long til end of surgery (100 mg-
5 cc)
-marcaine 25 mg (5 cc)
S&S of Marcaine wearing off:
-movement, can then dose epidural
-incr HR and BP (sensing pain)
-sensation of pressure
If epidural can’t be done, can do femoral nerve block
post op
[WU25]Polymethylmethacrylate
– strongly binds prosthetic device to pts bone
[WU27]Hypotension
Not seen much anymore
Ceramic ball used for younger patient (more movement
and activity but doesn’t last as long)
Titanium for elderly – lasts longer but less mobility
[WU29]Performing
high pressure lavage of the femoral shaft to remove debris (potential microemboli)
Cement can also gradual loosen resulting from breakage
of small pieces of cement over the years.
Cementless implants are made of porous material that allows natural bone
to grow into them – generally last longer and better for younger, active pts
but full recovery may be longer. Require
healthy active bone formation.
Cemented prosthesis are still preferred for older
(>80) and less active pts who have osteoporosis or thin bone (cortex)
[WU32]Surgeon
may request MAP > 80-90 mmHg to maintain function
Amplitude: strength of signal
Latency: time from one signal to next
[WU33]May
need neo gtt as you turn up sedation
[WU34]Give
succs after assessment by neurophysiology tech
[WU35]g/a
dose of propofol
[WU36]Non
organ dependent, no accumulation, quick off
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