Mod10: Orthopedic Surgery - Regional Anesthesia Flashcards
Orthopedic Surgery
Advantages of Regional Anesthesia:
Enhanced rehabilitation
Earlier d/c home
(Decreased time to hospital discharge)
Improved postop analgesia
Decreased incidence N/V
(Less incidence of N/V – not necessarily with SAB)
Less respiratory & cardiac depression
Improved perfusion
(Improved perfusion and blood flow via sympathetic blockade)
Reduced blood loss
Decreased risk thromboembolism
Decreased postop cognitive dysfunction
(Potential for less postop delirium and cognitive dysfunction if sedation avoided altogether but usually provided in combination with at least a little sedation, sometimes in combo with GA)
Orthopedic Surgery
Neuraxial (spinal & epidural) techniques can possibly contribute to a reduced incidence of thromboembolic events (DVT & PE) by leading to…
Enhanced LE blood flow
(as the result of sympathectomy (vasodilation))
↓ PLT reactivity
Systemic anti-inflammatory effects of LA
Factor VIII and von Willebrand factor
(An attenuated postoperative increase in factor VIII (plays an important role in coagulation) and von Willebrand factor – (vWF plays important role in adhesion of PLTs – so this goes up after surgery - neuraxial techniques lessen the extent of this increase))
Antithrombin III
(An attenuated postoperative decrease in antithrombin III (antithrombin serves to inhibit coagulation by neutralizing thrombin – so a decrease in this will lead to enhanced coagulation – so neuraxial technique lead to less of a decrease in the activity of antithrombin III after surgery))
Stress hormone
(Changes in stress hormone release)
Orthopedic Surgery
Limitations of Regional anesthesia:
Motor block limits rehabilitation & early ambulation
Risk for falls and other injuries
Hypotension
Orthopedic Surgery - Regional anesthesia
Conversion to GA:
Always be prepared to convert to GA
Blocks can fail partially or completely, or duration of surgery can outlast block, or other complications can occur that require conversion to a GA
Always have airway equipment ready and machine checked and ready
Orthopedic Surgery - Regional anesthesia
Selecting a technique depends on:
Duration of surgery
Duration of postop analgesia needed
Degree of sensory/motor block necessary to allow for rehabilitation and ambulation
Orthopedic Surgery - Regional anesthesia
Contraindications:
Patient refusal
Infection at injection site
Systemic coagulopathy
-
Orthopedic Surgery - Regional anesthesia
Why are patients on antiplatelet agents, thrombolytics, fondaparinux, DTIs, therapeutic regimens of LMWH Not candidates for receiving (neuraxial blocks) spinal or epidural?
Risk for spinal or epidural hematoma
Orthopedic Surgery - Regional anesthesia
Neuraxial block placement or removal of neuraxial catheter are Not contraindicated with subQ heparin when dose is
< 10,000 units daily
Orthopedic Surgery - Regional anesthesia
With LMWH, guidelines on neuraxial administration is dependent on the regimen
Once-daily dosing =>
Neuraxial anesthesia can be administered, and
Neuraxial catheters can be removed 10-12 hours after previous dose, and then
There will have to be delay of four hours until next dose can be administered
Also suggested that these guidelines be utilized when considering placement of a deep Peripheral Nerve Block and plexus blocks and catheters
Orthopedic Surgery - Regional anesthesia
With LMWH, guidelines on neuraxial administration is dependent on the regimen
Twice-daily dosing =>
Neuraxial catheters cannot be left in and…
Need to be removed two hours before first dose of LMWH
Also suggested that these guidelines be utilized when considering placement of a deep Peripheral Nerve Block and plexus blocks and catheters
Orthopedic Surgery - Regional anesthesia
Patients on coumadin/warfarin are not candidates for neuraxial block unless INR is ….
Catheters shouldn’t be removed unless the INR is…
Normal
1.5 or less
Also suggested that these guidelines be utilized when considering placement of a deep Peripheral Nerve Block and plexus blocks and catheters
Orthopedic Surgery - Regional anesthesia
Brachial Plexus Blocks
list them:
Interscalene
Supraclavicular
Infraclavicular
Axillary
Orthopedic Surgery - Regional anesthesia - Brachial Plexus Blocks
Interscalene block
may be used for which procedure?
Surgery on shoulder, arm, elbow
Fibers that innervate the ulnar side of forearm and hand (C8-T1) may be spared
thus not recommended for surgery on the hand
Orthopedic Surgery - Regional anesthesia - Brachial Plexus Blocks
Supraclavicular block
Indications - Risk - Precaution:
Surgery on arm, hand, forearm, elbow
shoulder surgery also possible
Pneumothorax is most common serious complication of supraclavicular block (about 1% incidence)
Block of phrenic nerve occurs frequently (50% of procedures) but usually causes no clinically significant symptoms
=> BUT for this reason, bilateral supraclavicular blocks not recommended d/t fear of bilateral pneumo’s and bilateral phrenic nerve paralysis
Patients with COPD may not be ideal candidates for this block
Orthopedic Surgery - Regional anesthesia - Brachial Plexus Blocks
Infraclavicular block
Indication and disadvantages:
Surgery for arm - elbow - forearm - hand
Disadvantages:
Risk of vascular puncture and patient discomfort associated with traversing the pectoralis major and minor muscles
Orthopedic Surgery - Regional anesthesia - Brachial Plexus Blocks
Axillary block
Indication - Potential compliactions - Anesthesia considerations
<u>Surgery for:</u>
Hand - Forearm - elbow
<u>Potential complications: </u>
Intravascular injection - Nerve injury from needle trauma - Intraneural injection - Hematoma
<u>Anesthesia of hand can be achieved by:</u>
injecting LA solution at level of FA to block median, ulnar and radial nerves
useful for hand surgery when TQ NOT used
also to supplement brachial plexus block w/ incomplete sensory distribution
each of these blocks use 3-5 mL of LA
Orthopedic Surgery - Regional anesthesia
Forearm Blocks:
Median nerve block
provides most of the sensory innervation to palm of hand
Ulnar nerve block
provides sensory innervation to dorsal and palmar sides of ulnar aspect of hand
Radial nerve block
Superficial radial nerve is the distal sensory branch of radial nerve that follows radial artery along its course through the forearm
Most patients have radial dominance of sensation on the dorsal aspect of the hand; supplies innervation to dorsum of thumb and dorsum of hand
For many surgeries, an epidural or SAB is easier to perform than attempting to provide same extent of anesthesia with multiple PNBs…but certain co-morbidities (CAD, bacteremia, anticoagulation) may make a PNB the best choice for anesthetizing a lower extremity
Orthopedic Surgery - Regional anesthesia
Lower Extremity Blocks
Femoral nerve
Saphenous nerve
Sciatic nerve
Popliteal
Ankle
Orthopedic Surgery - Regional anesthesia - Lower Extremity Blocks
Femoral nerve block:
Anterior aspect of thigh and knee - Medial aspect of leg
Typically combined with other blocks (such as sciatic nerve block) to provide complete anesthesia below the knee
Can do continuous FNB
Alone or in combo with other PNBs – very useful for postoperative analgesia
Orthopedic Surgery - Regional anesthesia - Lower Extremity Blocks
Saphenous nerve block:
Saphenous vein stripping or harvesting
In combination with sciatic nerve block for medial foot/ankle surgery
Orthopedic Surgery - Regional anesthesia - Lower Extremity Blocks
Sciatic nerve block:
Provides nearly complete anesthesia of foot and lower part of leg
Often combined with FNB to provide more extensive anesthesia for LE
Foot and ankle surgery - BKA - Analgesia following knee surgery involving the posterior compartment
Orthopedic Surgery - Regional anesthesia - Lower Extremity Blocks
Popliteal nerve block:
Provides sciatic nerve anesthesia near the point where the sciatic nerve divides into the common peroneal and tibial nerve components
Most commonly used for foot and ankle surgery, usually in combination with femoral and saphenous nerve blocks
=> for surgery on medial aspect of leg or if TQ used
Orthopedic Surgery - Regional anesthesia - Lower Extremity Blocks
Ankle block:
For distal foot and toe surgery
Involves anesthetizing five** separate **nerves
Two deep nerves (tibial and deep peroneal), and
Three superficial nerves (superficial peroneal, sural, and saphenous nerves)
All nerses, except the saphenous, are terminal branches of the sciatic nerve
The saphenous nerve is a sensory branch of the femoral nerve
Knowledge of the anatomy of the ankle is essential
Orthopedic Surgery - Intravenous Regional anesthesia (IVRA)
Bier block:
Named after August Bier
Simple method of anesthetizing the arm or leg
Involves IV injection of large volumes of dilute LA solutions into an extremity after occlusion of the circulation by a tourniquet
For surgeries lasting two hours or less
Severe tourniquet pain and max allowable TQ time limit the duration of the block
Duration of postop analgesia also limited – not usually used when postoperative pain is expected to be significant
Orthopedic Surgery
General or Regional Anesthesia will depend on?
Proposed surgery - Anticipated length - Position required
Patient acceptance - Co-morbidities
Anticoagulation status
Orthopedic Surgery
Blood Loss significant in:
Spinal
(Scoliosis - Instrumentation)
Pelvic fracture repairs
Long bone fracture repairs
Total hip arthroplasty
Trauma
Orthopedic Surgery - Blood Loss
Blood loss from Hip Fractures depends on:
Location of fracture
Subtrochanteric, intertrochanteric > base of femoral neck > transcervical (midportion of femoral neck), subcapital (femoral head/neck junction)
Certain fractures have greater blood loss, greater mortality
A preop Hct that is normal or borderline-low may be deceiving because hemoconcentration can mask occult blood loss
Orthopedic Surgery - Blood Loss - Hip fractures
Occult blood losses can be significant and this depends on a number of things, including:
The location of the fracture
A preop Hct that is normal or borderline-low may be deceiving because hemoconcentration can mask occult blood loss
Orthopedic Surgery - Blood Loss - Hip fractures
Hip fx patients are often dehydrated from a lack of adequate PO intake and this leads to:
hemoconcentration
A preop Hct that is normal or borderline-low may be deceiving because hemoconcentration can mask occult blood loss
Orthopedic Surgery - Blood Loss - Hip fractures
Preoperative Hct:
A preop Hct that is normal or borderline-low may be deceiving because hemoconcentration can mask occult blood loss
Always type and cross for hip fx, especially femoral neck, intertrochanteric and subtrochanteric. 500-1000mL.
Have blood available (in the OR fridge, preferably) before cut skin
Hip replacement, especially Revision hip replacement surgery, also associated with significant surgical blood loss.
Orthopedic Surgery - Blood Loss - Hip fractures
Reducing Blood Loss - How?
Induced hypotensive technique
Bloodless field greatly facilitates arthroscopic surgery (knee, shoulder)
Antifibrinolytics
Antifibrinolytics are used to prevent and treat surgical blood loss
Orthopedic Surgery - Blood Loss - Hip fractures - Reducing Blood Loss
Induced hypotensive technique
can be achieved with:
Volatile agents - NTG - NTP
Beta-blockers - Diltiazem
Orthopedic Surgery - Blood Loss - Hip fractures - Reducing Blood Loss
Risks of Induced hypotensive technique:
Spinal cord ischemia
Optic nerve ischemia
Ischemia to any organ
- Risks vs. benefits!!!!*
- Communicate with surgeon!!!*
Orthopedic Surgery - Blood Loss - Hip fractures - Reducing Blood Loss
Antifibrinolytics
Two types:
Lysine analogs
Tranexamic acid (TXA)
Epsilon-aminocaproic acid (AMICAR)
Serine protease inhibitor
Aprotinin
Orthopedic Surgery - Hip fractures - Reducing Blood Loss - Antifibrinolytics
Lysine analogs – TXA and amicar
Mechanism of action and more:
Competitively inhibit the binding site of plasminogen => this prevents the cleavage to plasmin and the subsequent fibrinolysis
Excreted by the kidneys and may be given IV or topically
Both seem to be equivalent in their efficacy, although there is more evidence to support TXA use
Research shows moderate decreases in peroperative blood loss in cardiac surgery, liver transplants, ortho operations and spinal fusions
These are less expensive than aprotinin
Only adverse effects are mild N/V with rapid infusion rates
No reports of increased risk of thromobolytic complications or renal failure…but some surgeons will withhold administration for patients with a cardiac history or history of thromboembolic events
Orthopedic Surgery - Hip fractures - Reducing Blood Loss - Antifibrinolytics
Serine protease inhibitor - Aprotinin
considerations:
Was reported to be more efficacious at reducing blood loss, minimizing transfusions, and preventing reoperations, especially in cardiac surgery
Removed from the market after studies demonstrated an increased risk in renal failure, MI, and death
However, aprotinin is now available in Canada and may be available again in the U.S. at some point
Orthopedic Surgery - Risks of Blood Product Administration
Which test screens blood donations for transfusion transmitted infections?
Nucleic Acid Testing
Since it was introduction to the developing world in the 1990s and early 2000s, the residual risk of infection from blood product administration has decreased dramatically
Transfusion-transmitted viral infections continue to receive the most focus because of their associated morbidity and mortality
Difficult to almost impossible to accurately quantify the true risk of transfusion transmittable infections
Orthopedic Surgery - Risks of Blood Product Administration
Potential viruses that can be transmitted include:
HIV - HCV - HBV
Human T-cell lymphocytic virus
CMV
(CMV is the most common transfusion-transmitted disease with an incidence of about 1-3%)
Orthopedic Surgery - Risks of Blood Product Administration
Contamination of blood components by which organism holds the largest risk of transfusion-related infection?
Bacterial contamination
Can progress to sepsis, which continues to be significant cause of morbidity and mortality related to transfusions
Orthopedic Surgery - Risks of Blood Product Administration
Common pathogens that lead to bacterial contamination come from:
Flora of the skin
Staphylococcus - Corynebacterium
Bacillus & Streptococcus
secondary to gam0 negative species such as <strong>e. coli</strong> and <strong>Enterobacter cloacae</strong> (kah or kee)
Orthopedic Surgery - Risks of Blood Product Administration
Whihc blood product carries the highest risk of bacterial contamination?
Platelets
Orthopedic Surgery - Risks of Blood Product Administration
Noninfectious Risks of Blood Product Administration
Two types:
Immune-mediated Transfusion reactions
Nonimmune-mediated transfusion reactions
Orthopedic Surgery - Noninfectious Risks of Blood Product Administration
Immune-mediated Transfusion reactions:
Febrile non-hemolytic
Allergic
Transfusion-related immunomodulation
Alloimmunization
TRALI
TA-GVHD
Posttransfusion purpura
Orthopedic Surgery - Noninfectious Risks of Blood Product Administration
Nonimmune-mediated transfusion reactions:
Transfusion-associated CV overload
Metabolic derangements
Iron overload
Microaggregate administration
Orthopedic Surgery - Nonimmune-mediated blood product transfusion reactions
Microaggregate administration:
During storage, microaggregates of cellular debris, PLTs, fibrin composition, and RBCs and WBCs collect in the blood
Standard blood filters avoid the infusion of these aggregates
Traditionally thought that you couldn’t safely administer blood with LR because of the calcium in LR
It was thought that calcium could chelate the citrate anticoagulant preservative used in stored blood and this could lead to blood clots
Several studies have negated this
As mixing blood with LR in ratios of more than 2:1 (RBC to LR) dose not demonstrate any clinical or experimental evidence of clot formation
Orthopedic Surgery - Risks of Blood Product Administration
How do we reduce the riskk for allogenic blood components?
Blood Conservation Strategies
such as:
Autologous Blood Transfusion (ABT)
Orthopedic Surgery - Blood Conservation Strategies
Autologous Blood Transfusion (ABT)
Three separate processes:
Preoperative autologous blood donation (PAD)
Acute normovolemic hemodilution (ANH)
Perioperative blood cell salvage (cell saver)
Orthopedic Surgery - Autologous Blood Transfusion (ABT)
Preoperative autologous blood donation (PAD):
Patients donated their own blood during the weeks before a planned surgical procedure
This eliminates the risk of viral infection and alloimmunization BUT still involves blood collection and storage => carries risk of clinical errors in this process, CV overload, bacterial infection, and transfusion-related immunomodulation
Indications:
Difficulty finding compatible blood products because of multiple antibodies or rare blood types, for patients refusing allogenic transfusions, and scoliosis surgery in adolescents
Each donation usually collects 450 mL – shouldn’t exceed 6 mL/kg
Can be repeated weekly until 72 hours before surgery
Patients rarely able to donate more than 4 units because of limited storage time and because hgb must remain over 11 g/dL before donation
If patients do have multiple antibodies and significant blood loss is anticipated, donated units can be frozen
Keep in mind that just because the patient donated the blood doesn’t mean they have to receive it.
Blood shouldn’t be administered to avoid waste
Ortho Sxy - Blood Conservation Strategies - Autologous Blood Transfusion (ABT)
Process of extracting blood from a patient shortly after induction of anesthesia and before surgical incision:
Acute Normovolemic Hemodilution (ANH)
Ortho Sgy - Blood Conservation Strategies - Autologous Blood Transfusion (ABT)
Acute Normovolemic Hemodilution (ANH)
Entails the removal of blood from a patient shortly after induction of anesthesia and before surgical incision
Euvolemia maintained using crystalloid and/or colloid replacement
The amount of blood removed varies between one and three units and about 450 to 500 mL constitutes one unit
Larger volumes may be withdrawn safely in certain circumstances
The aim of this blood conservation technique is to lower the patient’s hemoglobin concentration during surgery
This in theory minimizes the effect of surgical blood loss
Hemodiluted blood has less hemoglobin than it would in the absence of intraoperative hemodilution
The previously withdrawn whole blood is given back to the patient during or shortly after the surgical procedure.
ANH can be used as the sole blood conservation technique, or it can be combined with preoperative autologous donation
Whether ANH is effective in decreasing allogeneic blood transfusion is debatable, and outcome benefits have not been clearly demonstrated
ANH is not recommended for routine use
Ortho Sgy - Blood Conservation Strategies - Autologous Blood Transfusion (ABT)
Acute Normovolemic Hemodilution (ANH)
Patient Selection:
Considered for patients with normal initial hemoglobin (Hgb) levels who are expected to lose more than two units of blood (900 to 1000 mL) during surgery
This recommendation based on fact that most patients can safely tolerate intraoperative blood losses up to 2 units of PRBCs without need for transfusion
So the cost and labor required to implement intraoperative hemodilution isn’t justified in circumstances when blood loss isn’t expected to be more than this
It is safest when used in healthy, young adults, but can be used in other populationsGood option for Jehovah’s Witnesses, many of whom will consent to ANH if the blood is maintained in a closed circuit continuous flow system.
Ortho Sgy - Blood Conservation Strategies - Autologous Blood Transfusion (ABT)
Acute Normovolemic Hemodilution (ANH)
Contraindications:
Preop anemia
Significant cardiopulmonary comorbidity such as uncontrolled HTN, AS, or recent MI of CVA
In patients with a normal or high initial Hgb levels who are undergoing cardiac surgery, decreased blood viscosity associated with the induced anemia may have cardioprotective effects
Ortho Sgy - Blood Conservation Strategies - Autologous Blood Transfusion (ABT)
Acute Normovolemic Hemodilution (ANH)
What volume of blood can be drawn?
UpToDate not to withdraw more than 900 – 1000 mL
To be specific to the patient, blood is withdrawn based on target Hct
Target Hct will be based on individual patient history and baseline physiologic state but usually ranges from 25-30%
Use the allowable blood loss formula to calculate the volume to be removed
Max Allowable Blood Loss (ABL) calculation
Volume to be removed = [EBV X (HCTi – HCTf)]/HCTi
HCTi = initial Hct; HCTf = final or target HCT
This is an important formula for clinical rotations! This will let you know when you need to start thinking about giving blood
Average blood volumes are based on age and gender (for adult male this is between 70 and 75 mL/kg; for average adult female between 65 and 70 mL/kg; different for infants and neonates)
Averages HCTs: Men 42-52% - Women 37-47%
Ortho Sgy - Blood Conservation Strategies - Autologous Blood Transfusion (ABT)
Perioperative Blood Salvage (cell saver)
Requires use of double-lumen suction catheter - one port for aspiration from the surgical field and the other for addition of an anticoagulant solution (usually heparin or citrate)
Suctioned blood then collected in a reservoir, filtered to remove large debris, and centrifuges –> this results in red cell concentrates
Final step is washing and this clears the concentrates of residual contaminants such as plasma, PLTs, free hgb, cellular fragments, WBCs, and the remaining heparin or citrate
The red cells are resuspended in saline and then ready for reinfusion
This is usually given back to the patient immediately but can be stored at 4 degrees C for up to six hours
On average the Hct ranges between 60 and 70% but can be as low as 50% and as high as 80%
Has proven benefits for r_educing allogenic blood transfusion_ in major surgery, particularly ortho, spine fusion and off-pump cardiac surgery
Ortho Sgy - Blood Conservation Strategies - Autologous Blood Transfusion (ABT)
Perioperative Blood Salvage (cell saver)
Complications:
Rare and mostly associated with how the blood is suctioned from the patient or contamination from the surgical field
Ortho Sgy - Blood Conservation Strategies - Autologous Blood Transfusion (ABT)
Perioperative Blood Salvage (cell saver)
Risks include:
Nonimmunogenic hemolysis, fever, and contamination with various substances such as topical anticoagulants, urine, amniotic fluid, or bacteria
Orthopedic Surgery - Blood Conservation Strategies
Erythropoietin (EPO)
EPO is hormone produced primarily by the kidneys
Primary regulator of erythropoiesis (RBC production)
Release is stimulated endogenously when Hct drops below 30%
Also stimulated by physiologic hypoxia
Orthopedic Surgery - Blood Conservation Strategies
Erythropoietin (EPO)
Indicated for:
Indicated for refractory anemia, such as in renal failure patients
Also used for optimizing hgb levels in patients with preop anemia and in those patients participating in preoperative autologous donation
Cost effectiveness and the appropriate dosing regimens of using recombinant EPO is not clear
So routine use of EPO in the perioperative setting is not recommended at this time
Orthopedic Surgery - Blood Conservation Strategies
Jehovah’s Witnesses
Beliefs:
Jehovah’s witnesses are a part of an international well-established religious society
Believe in the literal translation of the Bible, including biblical instructions related to blood
Followers believe that once blood has left the body it shouldn’t be returned to anyone
If they were to receive blood that has left the body, this is grounds for excommunication and no hope for eternal life
Orthopedic Surgery - Blood Conservation Strategies - Jehovah’s Witnesses
Most understand and accept risks
Most understand and will accept the potential for death with the refusal of receiving blood products
Orthopedic Surgery - Blood Conservation Strategies - Jehovah’s Witnesses
Preoperative optimization:
Best management is perioperative optimization to maximize alternative blood conservation therapies
Orthopedic Surgery - Blood Conservation Strategies -<strong> Jehovah’s Witnesses</strong>
Clear discussion:
Need to have a frank and clear discussion with patient about specific concerns
Orthopedic Surgery - Blood Conservation Strategies - Jehovah’s Witnesses
Extracorporeal circulation:
Some will consent to receiving blood components, factors concentrates derived from blood (albumin) or extracorporeal circulation which may include CP bypass, ANH, and cell saver, as long as there is no break or disconnect of the circulation system with the patient’s body
Orthopedic Surgery - Blood Conservation Strategies - Jehovah’s Witnesses
Prohemostatic medications
In preparation for surgery, these patients might use prohemostatic medications such antifibrinolytics, vit K, recombinant factor VIIa, and desmopressin
Orthopedic Surgery - Blood Conservation Strategies - Jehovah’s Witnesses
Preoperative hgb:
Should have optimal preop Hgb by administering EPO, iron and supplemental B12 and folate
