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Advanced Principles- Fall 2018 > Orthopedics- Lower > Flashcards

Flashcards in Orthopedics- Lower Deck (39)
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1

What are some important things to consider regarding ortho procedures for the lower extremities?

  • Goal is to have post-operative analgesia that allows for rapid post-op rehabilitation
  • Reduce post-op morbidity and mortality d/t DVT and PE
    • Total hip 42-57% DVT and 0.9-28% PE
    • Total knee 41-85% DVT and 1.5-10% PE
    • Hip fx 46-60% DVT and 3-11% PE
    • Use LMWH and coumadin- anticoagulation sometimes started intra-op.   Think about this when selecting neuraxial anesthesia!
      • given 10 days for knees and up to 35 days post hip

2

What is an arthroplasty of the hip?

  • Large incision from iliac crest to mid-thigh
  • Muscle relaxation needed to access joint (spinal is ideal)
  • Femoral head is dislocated from acetabulum
  • Arthritic femoral head and portion of neck is excised
  • Acetabulum and femoral canal reamed to accept cemented metal/plastic prosthesis
    • fat and emboli can occur during this process
  • Cup, ball and stem replace femur head
  • blood loss 500-1,000 ml
  • Hgb threshold for replacement <10 conservative or <8 studies show no difference in outcomes

3

Anesthesia management for hip arthroplasty:

pre-op

monitoring

positioning

  • Pre-op
    • D/C anti-inflammatory meds at least 1 week prior
    • assess cervical flexion and extension and TMJ
    • Type & Cross
  • Monitoring
    • Elderly w/underlying disease
    • Cardiac function is difficult to assess pre-op d/t decreased mobility
      • A-line, CVP?
    • Careful fluid managment
    • Look for signs of emboli
      • hypoxia
  • Positioning
    • Lateral decub
      • V/Q mismatch
      • neurovascular complications
        • keep head and shoulders neutral
        • dependent arm abducted on padded arm rest
        • axillary artery- use roll
        • femoral nerve injury

4

Anesthetic for Hip Arthroplast

GA

  • Can do GA, 
    • good for muscle relaxation but need post-op pain management
      • consider with PCA or combined regional 
    • Pt may be difficult to position
    • ASA status and co-existing disease may be an issue
    • Best choice if pt is already anti-coagulated

5

Anesthetic for Hip Arthroplasty:

Regional

  • **Regional is anesthetic of choice!
    • Neuraxial
      • SAB (hypo or isobaric) or epidural
    • lumbar plexus block or psoas compartment block
    • Femoral nerve block- weakness of quadraceps increases post-operative falls
  • Adequate IV hydtration to avoid hypotension with sympathectomy
  • Considerations:
    • pt may be difficult to position
    • case length may predispose patient to discomfort
    • regional provides post-op pain control
    • airway access in lateral decub

6

How can you prevent blood loss during a hip arthroplasty?

  • deliberate hypotension
    • Diltiazem 
    • nitroprusside
    • nitroglycerin
    • beta blockers
    • regional anesthesia
  • Autologous donation
  • Cell saver
  • Tranexamic acid (TXA)

7

What might a surgeon inject into the periarticular space?

  • A "surgeon's Cocktail"
    • LA
    • epinephrine
    • an NSAID
    • an opioid
    • a corticostaroid
    • antibiotic

8

What are the stats on DVTs with Hip arthroplasty?

  • Morbidity from DVT >50% without prophylaxis
  • Morbidity from DVT is 10-20% with anticoagulant and compression device

9

What is Tranexamic acid?

How is it dosed?

Pharmacokinetics?

FDA approval?

  • Antifinbrinolytic that inhibits conversion of plasminogen to plasmin
    • reduces blood loss 29-54%
  • Dosing may depend of fibrinolytic response according to the type of surgery
    • Optimal dosing is procedure specific
    • best given pre-operatively
  • Pharmacokinetics:
    • low PB (3%)
    • Volume of distribution 9-12L
    • 5% metabolized by liver
    • 95% eliminated unchanged in kidney
    • elimiation 1/2 life 2 hours
  • FDA approved for hemopheliacs having teeth removed and women with heavy menses
    • Still used extensively

10

What is methyl Mehtacrylate?

What are some physiologic changes you may see?

  • Cement used to bind prosthetic to bone
  • cement mixing causes exothermic reaction and expands, causing pressure against bone surface
    • this pressure (intramedullary hypertension) pushes fat, air, and marrow into the femoral venous channels
  • Physiologic changes seen in 2-17% called bone cement implant syndrome (BCIS)
    • decreased SVR
    • hypotension 
    • hypoxia
    • arrhythmias
    • increased PVR
    • loss of consciousness
    • cardiac arrest

11

What is the first sign of BCIS?

Treatment?

  • First sign:
    • GA- drop in ETCO2
    • Regional- dyspnea or altered sensorium
  • Treatment:
    • 100% O2
    • aggressive fluids
    • correct hypotension with alpha agonists
  • Before cement:
    • 100% O2
    • optimize BP- have fluids on pressure bags
    • Avoid nitrous!
    • document cement timing on record

12

What can post-cement hypotension result in?

When is it common?

What are some possible explanations?

  • Profound post-cement hypotension can result in cardiac arrest and death
  • Uncommon in elective primary total hip replacement but not uncommon in high risk pts
  • Possible explanations:
    • caused by direct vasodilation or cardiac depression from methylmethacrylate
    • Caused by the forced entry of air, fat, or bone marrow into the venous system causing a PE

13

What is the other post-cementing concern?

When can it occur?

Treatment?

  • Hypoxia
    • can occur immediately after insertion or up to 5 days post-op
  • In the event of hypoxemia:
    • 100% FiO2
    • rule out atelectasis of dependent lung, hypoventilation, fluid overload
  • Post operative management
    • Nasal O2
    • pulse oximetry for several days
    • manage fluids/diuresis

14

What is fat embolism syndrome?

Treatment?

  • Most common 72 hours post-op in long bone fracture/surgery
  • Symptoms:
    • dyspnea
    • confusion
    • petechial rash on chest
    • decreased arterial oxygenation
    • EKG changes/tachycardia
    • diffuse alveolar infiltrates
    • pulmonary edema
    • sudden drop in ETCO2
  • Treatment:
    • possibly early corticosteroid treatment
    • otherwise supportive

15

What are the risk factors for venous thromboembolus?

  • high BMI
  • COPD
  • anemia
  • presence of pre-op DVT

16

What can be done to prevend venous thromboembolus?

  • D/C procoagulant medication
  • autologous blood donation
  • hypotensive anesthesia
  • Regional anesthesia
  • IV heparin during surgery
  • aspiration of intramedullary contents
  • pneumatic compression
  • knee high elastic stockings
  • early mobilization
  • chemoprophylaxis

17

What does the average femur neck fx patient look like?

What is the fracture table like?

  • 80 years old, most are women with multiple medical problems
  • In- hospital morbidity is 3% and 1 year after 20% have died
    • ASA status and age influence mortality
  • present with dementia
  • Fracture table:
    • must pad perineal post
    • arm ipsilateral to hip fx on arm board or sling and avoid xray obstruction

18

What does the ORIF of a femur look like

  • There will be reaming and an implant
  • lots of blood loss
  • Regional vs GA
    • regional (SAB or epidural) reduces perioperative risk of death, pulm complications and DVT by 30-50%
  • most common intraop cause of death are MI or PE

19

Knee arthroscopy:

Indication

position

What can be done in conjunction with an arthroscopy?

  • Indication- diagnose and treat intra-articular problems
    • torn meniscus/ACL
    • loose bodies
    • arthritis
    • infections
  • Position- supine with foot of OR table lowered for access
  • Multiple entry points at knee for scope.  Extra incisions may be required for meniscus repairs
  • Debridement and meniscectomy can be done in conjunction with arthroscopy
    • irrigation fluid 3-5L
    • be cautious with CHF

20

Anesthetic considerations for knee arthroscopy?

  • minimal EBL
  • tourniquet not often used
  • out patient
  • receive abx
  • consider general vs regional
    • cleaning out of knees dont have much pain
    • ACL surgeries are painful
    • usually regional for post op pain and GA during operation

21

How is an arhtroplasty of the knee done?

  • Femur patella and tibia are exposed
  • cartilage and bone excised with saw
  • new components cemented into place
  • tourniquet used
    • may have 2 units blood loss without tournequet
    • good amount of blood loss after tournequet is removed
  • positioning supine

22

What are some considerations for arthroplasty of knee?

  • Pts often have:
    • severe RA
    • degenerative OA
    • obesity
    • other significant co-morbidities
  • procedure is 1-3 hours
  • post op pain- regional is great option
  • morbidity:
    • DVT
    • Risk of post-op dislocation <35%
    • PE 1-7%

23

Optimal analgesia for total knee

  • Regional-neuraxial and peripheral blocks
    • femoral nerve
    • saphenous/adductor canal block
    • lumbar plexus
    • sciatic with femoral
    • selective tibial
    • obturator
  • Tourniquet usually 100 mmHg above SBP
    • must block all 4 nerves for tourniquet pain
      • femoral
      • lateral femoral cutaneous
      • obturator
      • sciatic
  • Spinal
    • hyperbaric (more sensory than needed)
    • isobaric
  • Epidural with continuous catheter
  • PNB- Femoral 3 in one or psoas

24

Foot and Ankle surgery:

position

anesthetic

  • Position:
    • supine or prone (for calcaneous)
  • Regional vs GA
    • selection of regional technique dependent on use of calf or thigh tourniquet, degree of wt bearing and ambulation post op
    • Thigh tourniquet >15-20 min requires GA or neuraxial
    • If no thigh tourniquet:
      • combined sciatic and femoral

25

General info about above knee amputations:

coexisting disease

surgical procedure

anesthetic management

post-op

  • Co-existing disease
    • DM
    • PVD
    • CV disease
    • trauma
  • Surgical procedure
    • leg completely excised at distal one third of femur
    • supine position
    • tourniquet used- no major blood loss
  • Anesthetic:
    • Regional- epidural + adjuncts (clonidine)
    • GA- multimodal (ketamine infusions/opioids)
  • Post-op
    • epidural- Bupivicaine 0.125-0.25% + Fentanyl 2 mcg/ml
    • psych considerations

26

Lower extremity amputations:

surgical description

anesthetic considerations

  • Surgical description
    • AKA: distal 1/3 portion of femur removed, stu,p fashioned with flap for prosthetic
      • traumatic AKA- stump not fashioned, return to OR every 1-3 days
    • BKA: mid leg portion removed
  • Anesthetic considerations
    • Gangeree, sptic, chronic disease, trauma
    • 250 ml EBL
    • mortality 10-20%
    • morbidity: phandom limb (most common), infection, PNA, MI, Emboli, CVA

27

What is the Psoas block?

  • Femoral, lateral cutaneous block, obturator nerve
  • motor and sensory to hip, anterior thigh, knee
  • sensory to medial upper and lower leg and ankle

28

Sciatic nerve

roots

location

motor

sensory

  • Nerve roots L4-5 + S1-3
  • exits the pelvis at greater sciatic foramen
  • travels under gluteus maximus
  • separates mid thigh into tibial and common peroneal nerves
  • Motor: posteror thigh, leg, and foot
  • Sensory: skin of posterior thigh/knee, lateral leg and foot

29

Sciatic nerve block:

indications

advantage

disadvantage

  • Indications:
    • anesthesia/analgesia to posterior distal thigh, posterior knee, lower leg/ankle/ foot
  • Advantage:
    • complete block of leg when combined with femoral nerve block
  • Disadvantages:
    • Deep nerve structure, difficult to identify
    • motor blockade can limit postop mobility and physical therapy

30

Blocking the _______ nerve causes foot drop.

Common peroneal