Anesthesia for Ortho Flashcards
Mixing polymerized mma powder with liquid mma monomer causes
polymerization and cross linking of polymer chains
________ reaction ultimately resulting in hardening.
Exothermic
Heat, expansion and hardening lead to ________ (> ______ mmHg).
-intermedullary hypertension
->500 mmHg
Residual mma monomer produces ______ and ______ SVR
vasodilation, decreases
_____________release may cause platelet aggregation, microthrombus (lungs) and CV instability
Tissue thromboplastin
Bone Cement Implantation Syndrome
-Hypoxia (increased pulmonary shunt)
-Hypotension
-Dysrhythmias (heart block and sinus arrest)
-Pulmonary htn (increased PVR)
-Decreased Cardiac Output
-Embolization most frequent during prosthetic insertion
Embolization most frequent during _______ ________.
prosthetic insertion
Surgical methods to minimize effects of MMA
-venting distal femur
-high pressure lavage of femoral shaft
Strategies to minimize effects of MMA
-Increase inspired O2 prior to mma
-Maintain euvolemia
-Vasopressor as needed
_______ ________ is associated with the highest risk of BCIS.
Hip arthroplasty
-others include knee, vertebra, and kyphoplasty
In the awake patient undergoing regional anesthesia, the first signs of BCIS are usually _______ and _______.
dyspnea and altered mental state
Under GA, the first sign of BCIS is a _______ _________.
Decrease EtCO2
First line treatment of BCIS includes…….(3)
100% FiO2
IV fluids
phenylephrine
Problems associated with Pneumatic Tourniquets
-Hemodynamic changes
-Pain
-Metabolic changes
-Arterial thromboembolism & -Pulmonary embolism
-Muscle and nerve injury
-Limb cooling
Cells _____ to pneumatic tourniquet shift to _______ metabolism, and ________ by products accumulate as long as tourniquet is inflated.
-distal
-anaerobic
-metabolic
Inflation pressure for upper extremity surgery:
70-90 mmHg above SBP
Inflation pressure for lower extremity surgery:
2x over SBP
2 ways that Tourniquet release stresses the body:
- restoring blood flow to extremity produces a relative decrease in circulating blood volume.
- The products of cellular hypoxia enter the systemic circulation.
Releasing the tourniquet produces transient changes that include:
-increased EtCO2
-Decreased core body temperature
-Decreased blood pressure
-Decreased SvO2
-Metabolic acidosis
Tourniquet pain usually begins at _____ after inflation.
45-60 minutes
_______ ________ is the most likely cause of tourniquet pain.
Tissue ischemia
Tourniquet pain is transmitted by _____ ______.
C fibers (slow pain)
Pain is _______ to analgesics.
Unresponsive
Under GA tourniquet pain manifests as ______ and _____. Consider _______ for the patient with CAD.
-hypertension and tachycardia
-esmolol
Cuff deflation drops _____ , _____, and _____.
CVP, MAP, and Pain
Cuff deflation: _____ increases and core temp ______
HR, decreases
Tourniquet pain is less common is _______ anesthesia vs _______.
Regional vs General
Metabolic waste products accumulate in tissue. Cuff deflation is rapid wash out of same: Increase _____,_______, _______ and _______.
Increased PaCO2, ETCO2, serum lactate and potassium
Tourniquet is contraindicated in ______ ______.
calcified arteries
Prolonged inflation = > ___ hours.
Causes:
2 hours
transient muscle injury
permanent nerve injury
rhabdo
Triad of Fat Emboli Syndrome:
dyspnea, confusion, petechiae
(usually w/ in 72 hours of long bone Fx)
FES can happen from ____,____ and _____ as well
CPR, liposuction, IV lipids
FES diagnosis
-petechiae of chest, upper extremities, axillae and conjuctivae
CXR = ARDS
FES: fat globules in _____,_____and _____.
retina, urine, sputum
FES: Under GA see decline in ______ and _____ and a rise in ______
decline - ETCO2 and SPO2
rise- PAP
DVT and PE major source:
M&M post pelvic and lower extremity surgery
Risk factors of DVT and PE:
age > 60yr, obesity, tourniquet, procedures >30 min, lower extremity fx, and immobilzation > 4 days
Highest risk are in knee and hip replacements
What decreases risk of both DVT and PE?
Neuraxial Anesthesia
DVT and PE pathogenesis:
venous stasis and hypercoaguability from inflammation
Neuraxial Anesthesia reduces DVT and PE in what ways:
-Sympathectomy induced increases in venous blood flow
-Antiinflammatory effects of local anesthesia
-Decreased platelet activity
-Decreased rise in factor VIII and Von -Willebrand factor
Less fall in antithrombin III
-Less stress hormone release
Hallmarks of hematoma are _____ _____ and_______ _______ weakness.
back pain, lower extremity
Joint manipulation type of drugs:
IV agents with short duration (Propofol)
JM: General preferred to regional because:
-LMA/ mask/ett
-Profound relaxation allows surgeon to distinguish anatomical limitations from patient guarding
-Muscle relaxant, succ or roc may be needed
Hip fracture mortality ___% during initial hospitalization and ___% for first year
10%
25%
Reasons to delay Hip fx surgery
-coagulopathy
-uncompensated HF
Hip fx: Blood?
Blood in the room because you cant put a tourniquet on a hip
Hip Fx: Predictors of peri-op mortality
Age >85 yrs
H/o cancer
Baseline/pre-op alteration in neuro status
Post-op chest infection
Post-op wound infection
Hidden blood loss:
Large amounts of blood can be sequestered around fracture
Blood loss from greatest to least from hip fracture
subtrochanteric,intertrochanteric > base of femoral neck > transcervical, subcapital
Hip Fx: Bigger fracture?
Consider arterial line and large bore iv for transfusion, hemodynamic monitoring
Use short acting drugs
Use lower solubility agents
Minimize postop cognitive impairmen
Benefits of arthroscopy
Less ebl
Less post-op pain
Less rehab time
Nerve injury from Traction table
Pudendal Nerve
LMA for which arthroscopic surgeries?
knees, wrists
Which arthroscopic surgery requires an ETT?
shoulder
Position for THA
lateral decubitus
Embolic event most frequent at insertion of ________ _________.
femoral component
Highest rate of DVT for all ortho procedures
Total Knee Arthroplasty
Nerve block for upper extremity surgery
Interscalene block of brachial plexus helpful.
Done preop, very good 80% of time.
Anesthesia considerations for Re-implantations:
Careful attention to positioning
Maintain body temp!!!
Regulation of fluids
Maintenance of blood flow
Optimal HCT 28-30%
Keep warm
Avoid vasoconstrictors
Dextran or heparin infusion intraop
Most common cause of toxic plasma concentration of local is….
inadvertent intravascular injection during regional anesthesia
Most frequent symptom of LAST is…..
What is the exception?
Seizure
Bupi is the exception
-cardiac arrest occurs before seizure
LAST is more common with __________ than with ________ anesthesia
peripheral nerve blocks, epidural
Highest risk for LAST?
Bier Block
How long to leave tourniquet inflated for bier block.
20 minutes
_______ and _____ will worsen the symptoms of LAST.
Hypoxia and Acidosis
Difficulty of cardiac resuscitation (Locals)
Bupivacaine > Levobupivacaine > Ropivacaine > Lidocaine
The risk of bupivacaine toxicity is increased with _____, _____, ______, and ______
-pregnancy
-beta-blockers
-calcium channel blockers
-digitalis
If Epi used for LAST, keep dose below ___ mcg/kg
1 mcg/kg
Ultimate treatment for LAST Is _______
lipids!
Lipid emulsion dose for patient over 70kg:
Bolus= 100ml over 2-3 minutes
Infusion= 250 ml over 15-20 minutes
if remains unstable repeat bolus and/or double infusion rate
Lipid emulsion dose for patient under 70kg:
Bolus= 1.5 mk/kg of lean body weight over 2-3 mins
Infusion= 0.25 ml/kg/min
if remains unstable repeat bolus and/or double infusion rate
max dose is 12ml/kg
