ANESTHESIA FOR ORTHOPEDIC SURGERY

David Hirsch M.D.

“There is a fracture, I need to fix it.” (http://www.youtube.com/watch?v=3rTsvb2ef5k)

Disclosures

none

Topics

Special considerations Hip Surgery Knee Surgery Upper Extremity Spine Surgery Peripheral Nerve Blocks

Special considerations

Bone cement (polymethylmethacrylate) Binds prosthetic device to patient’s bone Can cause embolization of fat, bone marrow,

cement and air into femoral venous channels Most frequently with femoral prosthesis

Bone Cement Implantation Syndrome Hypoxia – increased pulmonary shunt Hypotension Dysrhythmias- heart block and sinus arrest Pulmonary hypertension – increased PVR Decreased cardiac output

Bone Cement

Anesthetic Strategy Maximize Fi02 Eu-volemia (monitor CVP) Vent hole in distal femur to decrease pressure High pressure lavage to remove debris

Tourniquet

Help create bloodless field Can cause pain, metabolic alterations, hemodynamic changes Increase in blood flow in central circulation Pain severe enough to require substantial supplementation

despite regional block Goal < 2 hours

Can cause transient muscle dysfunction Permanent peripheral nerve damage Rhabdomyolysis

Lower Extremity Can lead to DVT

Sickle Cell Pay attention to maintaining normocarbia, hydration,

normothemria

Tourniquet

Deflation Fall in CVP, ABP Pulse increase Temp Decrease Increased PaC02,EtC02, lactate and potassium

from ischemic limb Cause increase in Minute Ventilation Rare-dysrhythmias

Re-oxygenation Can worsen ischemic injury due to formation of

lipid peroxides

Emboli

Fat Embolism Syndrome 10-20% mortality Within 72 hours following long-bone or pelvic

fx Triad of dyspnea, confusion and petechiae

1)Fat globules released by disruption in bone enter circulation through tears in medullary vessels

2) or chylomicrons resulting from aggregation of circulating free fatty acids

Embolism

Symptoms Coagulation Abnormalities

Thrombocytopenia, increased clotting time Pulmonary

Range from Mild hypoxia to ARDS Under GA

Decline in ETCO2, arterial oxygen saturation Increase in PAP ECG-ischemic ST changes and right sided heart strain

Treatment: Prophylactic: early stabilization of fracture Supportive: 02, with CPAP, high dose

corticosteroid

Fat Embolism

Fat Emboli

DVT/PE

Increased risk DVT/PE Higher risk

Obesity, age > 60, procedure > 30 min, tourniquet, LE fracture and immobilization > 4 days Older studies: PE as high as 20% with 1-3% fatal PE

Anticoagulation as soon as possible Improvement in occurrence rate

prophylaxis early rehab regional anesthesia?

DVT/PE

Neuraxial Anesthesia Alone or with general can reduce embolic

complications Sympathectomy induced increase in LE venous blood

flow Systemic anti-inflammatory effect of local anesthetic Decreased platelet reactivity Increase in factor 8,vW Decrease in Antithrombin III Decrease in stress hormone release

Contraindicated with full anticoagulation therapy Generally not done within 6-8 hour prophylactic

heparin dose or 12-24 hours of LMWH

Hip Surgery

Pre-op Mostly elderly Pre-op hypoxia

Fat emboli, bibasilar atelectasis, pulmonary congestion/effusion or infection

General vs. regional Lower mortality early post-op period for

regional After 2 months, no difference in mortality

Spinal Hypobaric technique allows easier positioning

Total Hip Arthoplasty

Etiology Osteoarthritis: repetitive trauma Rheumatoid Arthritis

Atlanto-axial instability: Preoperative:

Flexion and extension radiographs of the cervical spine:

Especially those on immune therapy, steroids methotrexate

Intubate with fiberoptic/video assist Limited jaw mobility

Total Hip Replacement

Intra-op Lateral Decubitus +/ - Arterial Monitoring Considerations

Bone Cement Implantation Syndrome Blood Loss Thromboembolism

Most often during insertion of femoral prosthesis

Total Hip Arthoplasty

Bilateral Recommended to monitor PA pressure in case

of emboli PAP> 200 during first hip, contralateral should

be postponed Revision

Significant blood loss If possible, controlled hypotension

Knee Surgery

Knee Arthroscopy Knee Replacement

Knee Arthroscopy

Pre-op considerations Usually young/healthy however increasing

frequency in elderly Intra-op Management

Surgeons favor bloodless field (tourniquet) LMA Neuraxial vs. alternative regional

Post-op Pain Control Multi-orifice catheter (Painball) Corticosteroid injection

Knee Surgery: Regional

Regional: 3 options Femoral with or without sciatic block Psoas Compartment Block Local Infiltration

Psoas Compartment Block

Total Knee Replacement

Pre-op Usually secondary to OA/RA

Intra-op Blood loss decreased by tourniquet Bone cement implantation syndrome less

likely then hip Regional technique similar to Arthroscopy

Continuous catheter (Epidural vs. femoral)

Upper Extremity Shoulder

Open or Arthoscopic Lateral Decubitus or Beach Chair

Interscalene block preferred +/- interscalene catheter Side effects:

Phrenic nerve palsy Horner's syndrome

Mild controlled hypotension requested Elbow

Open or Arthoscopic Infra-clavicular block preferred

Beach-Chair Position

Head and Upper torso elevated 30-90 degrees Complications

Stroke, Ischemic Brain Injury and Vegetative State Decreased cerebral Perfusion Each cm of head elevation above heart there is a

decrease in arterial blood pressure of .77 20 cm not uncommon

Approximately 15-16 mm Hg gradient from heart/cuff Measure height difference at External Auditory

Meatus Same level of Circle of Willis

Avoid in Elderly, HTN Compromised autoregulatory curve

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&docid=-aAMKTgQ1QEZmM&tbnid=kwhuPHalQi3IvM:&ved=0CAUQjRw&url=http%3A%2F%2Fwww2.massgeneral.org%2Fortho%2FASC_Anesthesia_Main.htm&ei=my25UZCPK47k9gSu4IHoCQ&bvm=bv.47883778,d.dmg&psig=AFQjCNEzCr9T7e0Pw-HQ4XKwmlX9Qh0jgA&ust=1371176726811398

Spinal Surgery

Most common Posterior spinal fusion Scoliosis correction Combined antero-posterior procedures

Anesthetic Considerations Neuro-monitoring

Awareness (+/- BIS) Position

Often prone for long periods of time Mayfield tongs or Prone Pillow

Blood Loss

Post-Operative Vision LossCases > 6 hour with > 1 L blood loss highest risk

Ischemic Optic Neuropathy Variation in blood supply Orbital Edema

Increased venous pressure can cause decreased arterial flow

Ocular Perfusion Pressure Function of MAP and IOP (Intraocular Pressure) OPP = MAP – IOP Prone position associated with increased IOP

Central Retinal Artery Occlusion Emboli Direct pressure on Eyeball

Post-Operative Vision Loss

Visual loss Registry with ASA Most Healthy/Prone position

93 total 83 Ischemic Optic Neuropathy 10 Central Retinal Artery Occlusion 55 bilateral

Mean blood loss 2 L Range .1 – 25 L

Blood loss > 1L and case longer then 6 hour = 96%

References

Butterworth IV JF, Mackey DC, Wasnick JD. Chapter 38. Anesthesia for Orthopedic Surgery. In: Butterworth IV JF, Mackey DC, Wasnick JD, eds. Morgan & Mikhail's Clinical Anesthesiology. 5th ed. New York: McGraw-Hill; 2013. http://www.accessmedicine.com/content.aspx?aID=57236471. Accessed June 12, 2013.

Chelly, Jacques. Peripheral Nerve Blocks: A Color Atlas. 2009.

Miller, Ronald D. and Manuel C. Pardo. Basics of Anesthesia , Sixth Edition.Chapter 32 , 499-513Copyright © 2011,