Orthopedics- Lower Flashcards
1
Q
What are some important things to consider regarding ortho procedures for the lower extremities?
A
- 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
Q
What is an arthroplasty of the hip?
A
- 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
Q
Anesthesia management for hip arthroplasty:
pre-op
monitoring
positioning
A
- 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
- Lateral decub
4
Q
Anesthetic for Hip Arthroplast
GA
A
- 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
- good for muscle relaxation but need post-op pain management
5
Q
Anesthetic for Hip Arthroplasty:
Regional
A
- **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
- Neuraxial
- 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
Q
How can you prevent blood loss during a hip arthroplasty?
A
- deliberate hypotension
- Diltiazem
- nitroprusside
- nitroglycerin
- beta blockers
- regional anesthesia
- Autologous donation
- Cell saver
- Tranexamic acid (TXA)
7
Q
What might a surgeon inject into the periarticular space?
A
- A “surgeon’s Cocktail”
- LA
- epinephrine
- an NSAID
- an opioid
- a corticostaroid
- antibiotic
8
Q
What are the stats on DVTs with Hip arthroplasty?
A
- Morbidity from DVT >50% without prophylaxis
- Morbidity from DVT is 10-20% with anticoagulant and compression device
9
Q
What is Tranexamic acid?
How is it dosed?
Pharmacokinetics?
FDA approval?
A
- 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
Q
What is methyl Mehtacrylate?
What are some physiologic changes you may see?
A
- 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
Q
What is the first sign of BCIS?
Treatment?
A
- 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
Q
What can post-cement hypotension result in?
When is it common?
What are some possible explanations?
A
- 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
Q
What is the other post-cementing concern?
When can it occur?
Treatment?
A
- 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
Q
What is fat embolism syndrome?
Treatment?
A
- 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
Q
What are the risk factors for venous thromboembolus?
A
- high BMI
- COPD
- anemia
- presence of pre-op DVT
17
Q
What does the average femur neck fx patient look like?
What is the fracture table like?
A
- 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
