anesthesia for orthopedic surgery

Question 1

what are common characteristics seen with orthopedic patients?

Answer 1

• many have arthritic joints/deformities
• many have limited ROM in neck
• require careful positioning
• may need help moving to OR table
• fracture patients may have full stomachs
• may have increased bleeding
• increased risk of fat emboli, DVT, and PE
• exposure to large amounts of radiation
• 80% young and healthy; 20% old w/ fall or bad arthritis (inactive)

Question 2

describe rheumatoid arthritis

Answer 2

• immune related, progressive inflammation of synovial joints (not just joint wear and tear)
• systemic manifestations
• multiple joint involvement, deformity
• chronic NSAID use (GI bleeding, renal toxicity, platelet dysfunction)

Question 3

what are issues seen r/t joint deformity?

Answer 3

• invasive lines and monitoring challenges
• immobility and decreased endurance of patients
• cervical and TMJ issues: check neck ROM, mouth opening
• atlantoaxial subluxation: C-spine films to evaluate and determine if fiberoptic intubation is indicated if greater than 5 mm instability exists
• cricoarytenoid arthritis: hoarseness, airway obstruction

Question 4

what are CV effects of rheumatoid arthritis?

Answer 4

• pericardial thickening and effusions
• myocarditis
• coronary arteritis
• conduction defects
• cardiac valve fibrosis (AR)

Question 5

what are pulmonary effects of rheumatoid arthritis?

Answer 5

• pleural effusions
• pulmonary nodules
• interstitial pulmonary fibrosis

Question 6

what are hematological effects of rheumatoid arthritis?

Answer 6

• anemia
• platelet dysfunction
• thrombocytopenia

Question 7

what are endocrine effects of rheumatoid arthritis?

Answer 7

• adrenal insufficiency (on steroid treatment)

- impaired immune system

Question 8

what are dermatologic effect of rheumatoid arthritis?

Answer 8

thin atrophic skin

Question 9

describe positioning for orthopedic cases

Answer 9

• usu. done after pt. is anesthetized
• usu. supine, sitting lateral decubitus or prone
• protect face from injury: eyes/nose, pad face
• sitting increases risk for air embolus: head and neck neutral position; avoid N2O
• arms over chest may impede ventilation
• sitting can reduce CPP
• stretch injuries

Question 10

describe used of regional anesthesia for orthopedic cases

Answer 10

• excellent advantages but can be unreliable
• supplement w/ IV opioids
• may use more for upper extremity surgery
• may be used in combo w/ GA for post op pain control
• reduced blood loss in some surgeries
• bier block commonly w/ wrist and hand surgeries
• neuraxial or peripheral nerve catheters allow continuous infusions in the post op period

Question 11

describe shoulder surgery

Answer 11

• lateral or “beach chair” position (lateral is best)
• open or arthroscopic (90%) technique
• positioning challenge: ears, eyes, boney areas
• may use LMA
• interscalene block combine w/ GA
• controlled hypotension (low 90s systolic allows surgeon to see shoulder joint)
• irrigation pressure during arthroscopic surgery must be higher than systemic pressure (too high can lead to injury)
• associated w/ nerve injury
• VAE possible in “beach chair” position

Question 12

how can CPP be estimated?

Answer 12

• level of the external auditory meatus and tragus correlates w/ the Circle of Willis, where CPP can be measuered
• lower pressure than level of heart d/t the vertical column and hydrostatic pressure difference
• *each 10 cm distance from heart equals 7.5 mmHg lower

Question 13

describe arthroscopic surgery

Answer 13

• knee, shoulder, elbow, wrist, hip , ankle
• less invasive w/ reduced blood loss
• bloodless surgical field
• minor incision w/ less post op pain
• reduced blood pressure on non tourniquet joints optimizes surgical field
• irrigation fluid 60-80 mmHg distends joint
• high pressure w/ long duration associated w/ sub q emphysema and tension pneumothorax
• keep systemic BP as low as possible to still maintain CPP so surgeons won’t have to increase their pressure

Question 14

describe spinal surgery

Answer 14

• most often to decompress cord or nerve root
• neuro and ortho surgeons perform
• multilevel instrumentation w/ plates, rods, and screws for spinal instability
• GA w/ or w/o paralysis
• if transthoracic, may need to deflate the lung
• airway challenges: prone position, cervical immobility
• can be done posterior or anterior approach
• may develop CSF leak requiring a vital capacity maneuver (VCM or valsalva)

Question 15

describe cervical spine surgery considerations

Answer 15

• prone, sitting, or supine position
• arthritic conditions may cause ROM issues (may require FO)
• major arteries and veins are near by (check distal pulses; can use ear probe oximeter)
• potential recurrent laryngeal nerve injury (some surgeons don’t allow muscle relaxant use)
• airway swelling could be post op issue
• identify and document preexisting neuro deficits
• prevent too much neck and head traction (pad)
• coughing or bucking must be prevented (LTA kit)

Question 16

what arthritic conditions may cause ROM issues?

Answer 16

• TMJ dysfunction: limited jaw opening
• atlantoaxial instability: limited neck ROM
• potential airway management challenge, may require F/O intubation

Question 17

describe lumbar spinal surgery

Answer 17

• can be minimally invasive or more extensive
• prone position using prone chest rolls
• brachial plexus at risk
• keep arms and shoulders less than 90 degrees
• abdominal compression
• impedes venous return
• diaphragm is cephalad, decreasing FRC and Vt
• biggest fear: eye injury or vision loss
• long procedures lead to large blood loss

Question 18

describe spinal fusion

Answer 18

• fusion of two or more vertebra are indicated
• bone grafting autologous or cadaveric
• artificial disk is inserted into space
• plates, rods, screws stabilize the two vertebra
• restores the correct distance b/w vertebra as a “cage” is constructed to hold the vertebra in place and prevent collapse
• risk hitting vertebrae, tear dura, or hit spinal cord

Question 19

what are anesthesia implications for spinal fusion?

Answer 19

• identify and document preexisting neuro deficits
• pressure off eyes, ears, nose, breast, genitalia
• blindness can occur
• ischemic nose or chin
• limited access to airway, monitoring leads
• longer procedures: warm patient, temp monitors
• greater blood loss: cell saver, typed and cross matched
• scoliosis pt. may have restrictive lung disease
• major vessels are in close proximity to spine
• monitor blood loss and temp*

Question 20

describe hip fracture

Answer 20

• typically elderly, frail, debilitated, dehydrated pts. w/ existing comorbid conditions
• supine position
• fracture table
• traction applied to fracture
• perineal post
• ipsilateral arm is placed on chest
• hypobaric and hyperbaric SAB can be used
• fat embolism common

Question 21

describe hip replacement

Answer 21

• typical pt. is elderly, likely arthritic history
• blood loss can be large (watch blood loss!)
• lateral decubitus position allowing greater ROM
• large incision
• prosthetic can be cemented or uncemented
• bilateral hip surgery contraindicated if declining pulmonary function occurs after first hip surgery (wait 6 mth.)
• axillary/chest roll
• up arm supported and stabilized
• down ear should be flat or no pressure

Question 22

what causes declines in pulmonary function during hip replacements?

Answer 22

when banging prosthetic in, micro emboli will scatter from hip bone and will see a drop in the O2 saturation as micro emboli reach lungs

Question 23

describe knee replacements

Answer 23

• usu. elderly, arthritic
• supine position
• tourniquet used
• more painful than hip
• high incidence of DVT
• many regional anesthetic options
• mostly older, at risk, out of shape population vs. young, active, in shape arthroscopic knee surgery
• prosthetics cemented to femur and tibia

Question 24

what regional anesthetic options are available for knee replacements?

Answer 24

• femoral 3 in 1 block (LFC, Obt, FN) combined w/ spinal

- femoral catheter used post op for pain control

Question 25

describe closed reduction

Answer 25

• usu. very short procedures
• hips, shoulders, wrist, elbow, fingers (many times popped out of place)
• short acting paralysis usu. required (muscle tone may be working against surgeon popping back in )
• may be done w/ mask ventilation
• done many times w/ propofol bolus since short time (usu. minutes) are required for reduction success

Question 26

describe methylmethacrylate cement

Answer 26

• used to bind prosthetic to bone
• exothermic reaction occurs which hardens cement and expands (causes lysis of blood cells and marrow)
• intermedullary hypertension: embolization of air, fat, marrow, and cement
• systemic absorption: decreased SVR d/t vasodilatory effects; release of tissue thromboplastin, platelet aggregation, microemboli formation
• *drop in O2 Sat
• *cant smell if pregnant

Question 27

describe bone cement implantation syndrome

Answer 27

• emboli migrate to pulmonary system
• hypotension
• hypoxia
• reduced cardiac output
• dysrhythmias
• shunt
• pulmonary hypertension
• increase FiO2
• adequate hydration

Question 28

describe the pneumatic tourniquet

Answer 28

• utilized to minimize blood loss and optimize surgical field
• exsanguination: esmarch bandage; distal to proximal
• cuff overlap should be 180 degrees from nerve bundle
• inflation pressure: determined by BP
• typically 100 torr lower ext. and 50 torr upper ext. over SBP
• venous tourniquet can occur
• neurological damage may occur if over 2 hours or if overlap is over nerve bundle

Question 29

what are physiologic effects of tourniquet inflation?

Answer 29

• initial rise in SVR, CVP, PVR
• displaced blood volume (300-500 ml) w/ exsanguination
• prolonged inflation increased HR and BP (cant control)

Question 30

what are physiologic effect of tourniquet deflation?

Answer 30

• metabolic acidosis: increased potassium and CO2 levels
• HR increase
• temp decrease (warm blood goes back to cool limb and cools rest of body
• hypotension (most common)
• sudden reduction in SVR and PVR
• wash out of ischemic metabolites (thromboxane)
• *during inflation, distal to TQ, anaerobic cellular respiration occurring creating lactic acid and CO2 which is washed back into system w/ deflation (acidosis, hypotension)

Question 31

what are neurological effects of TQ?

Answer 31

• abolition of SSEP and nerve conduction within 30 min
• more than 60 min causes TQ pain and HTN
• more than 2 hrs can result in post op neuropraxia
• evidence of nerve injury may occur at the skin level underlying the TQ

Question 32

what are muscle effects of TQ?

Answer 32

• cellular hypoxia within 2 min
• cellular creatinine value declines
• progressive cellular acidosis occurs
• endothelial capillary leak after 2 hrs.

Question 33

describe TQ pain

Answer 33

• usu. an hour after inflation
• increase in HR and BP
• ischemia, nerve fiber compression
• burning, dull aching, throbbing pain (c fibers)
• IV analgesics minimally effective
• opioids added to local anesthetic have been shown to help
• deflation for 10-15 min can help
• quality/intensity of block vs. level of block

Question 34

describe C fibers

Answer 34

• unmyelinated
• slow conducting
• burning, dull aching, throbbing pain w/ TQ inflation

Question 35

describe A delta fibers

Answer 35

-pinprick, tingling pain after deflation

Question 36

describe long bone fractures

Answer 36

• fracture of femur and tibia
• fat released into the circulation
• fat embolism syndrome (triad)
• DVT and PE can occur
• VAE can also occur

Question 37

describe fat embolus

Answer 37

• common in fractures of femur and tibia (long bones)
• fat globules are released into the blood
• fat embolism syndrome triad occurs 12-24 hrs. later
• tachycardia and/or ST segment changes may occur
• fat in the urine and sputum, conjunctiva may be present
• coexisting lung disease at greater risk

Question 38

what are the consequences of fat globules released in the blood?

Answer 38

• impaired pulmonary perfusion
• endothelial damage to pulmonary capillaries
• alveolar wall damage
• pulmonary congestion

Question 39

what makes up the fat embolism syndrome triad?

Answer 39

• petechiae (axillary, subconjunctival)
• dyspnea
• confusion, mental changes

Question 40

what is treatment for fat embolism syndrome?

Answer 40

• O2
• fluids
• steroids if indicated (fat emboli can cause inflammatory reaction in lungs)
• aggressive ventilation required

Question 41

describe DVT and PE

Answer 41

• more common after total hip and total knee arthroscopy
• mechanisms: venous stasis, hypercoagulable state, platelet aggregation
• TQ greatly contributes to problem: venous stasis
• epidural or spinal reduces DVT (higher levels of plasminogen and plasminogen activators; hyperkinetic blood flow)
• may be attributed to allowing early ambulation
• utilization of anticoagulants

Question 42

describe post op pain management

Answer 42

• NSAIDS (if not contraindicated) and IV opioids
• systemic opioids via PCA device (improved anesthesia, decreased total opioid consumption, increased pt. and nurse satisfaction)
• intra-articular injection: combo of opioids and LA
• continuous post op neuraxial and peripheral analgesia: better pain relief, faster ambulation and overall rehabilitation, better post op joint mobility