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Anesthesia for Spine Surgery

Anesthesia for Spine Surgery. Nicole Weiss, MD March 23, 2012. Concerns for Spinal Surgery?. Neuromonitoring &/or Wake-Up Test Significant Blood Loss Requiring Transfusion Postoperative Vision Loss Spinal Trauma- Cervical Spine Injury & Spinal Shock Postoperative Airway Compromise

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Anesthesia for Spine Surgery

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  1. Anesthesia for Spine Surgery Nicole Weiss, MD March 23, 2012

  2. Concerns for Spinal Surgery? • Neuromonitoring &/or Wake-Up Test • Significant Blood Loss Requiring Transfusion • Postoperative Vision Loss • Spinal Trauma- Cervical Spine Injury & Spinal Shock • Postoperative Airway Compromise • Venous Air Embolism • Preserving Spinal Cord Perfusion • Bronchial Blocker to Assist in Anterior & Lateral Thoracic Procedures

  3. Case One • A 16 y/o female is undergoing instrumentation and fusion for scoliosis. • What anesthetic would you pick for this case & why? • In the middle of the case, motor evoked potentials are lost on the right side. • What is the next step?

  4. Pick the number of hours of spinal cord ischemia that is associated with virtually no recovery of neurologic function • One Hour • Two Hours • Three Hours • Four Hours

  5. Which of the following regimens will provide for the fastest wake-up? • Propofol & Remifentanil • Propofol & Sufentanil • Desflurane & Sufentanil • Desflurane & Remifentanil

  6. Loss of Motor Function • Etiology of the loss of motor function during surgery • Trauma, Ischemia, Hematoma, Compression • After three hours of critical ischemia there is usually no neurologic recovery • When patients awaken paraplegic there is little chance of full neurologic recovery • Prevention: Neuromonitoring & The Wake-Up Test

  7. The Ideal Regimen • Preserves SSEPs & MEPs while maintaining an adequate depth of anesthesia • Allows for a quick wake-up to assess motor function • Ensures that the patient can be kept comfortable even during a wake-up test

  8. Intraoperative Wake-Up Test and Postoperative Emergence in Patients Undergoing Spinal Surgery: A Comparison of Intravenous and Inhaled Anesthetic Techniques Using Short-Acting Anesthetics • RCT published in 2004 Anesthesia & Analgesia • 54 patients assigned to one of the following regimens: • Propofol & Remifentanil • Propofol & Sufentanil • Desflurane & Remifentanil

  9. Intraoperative Wake Up Test

  10. Steps for a Wake-Up/Stagnara Test • Discontinue all anesthetics • Reverse neuromuscular blockade • If spontaneous respirations don’t occur, administer naloxone (in low increments) • Stabilize head to prevent extubation • Ensure upper extremity movement prior to lower extremity movement • Be ready to re-anesthetize

  11. Case Two • 52 y/o female with h/o of chronic low back pain admitted for a transpedicularosteotomy with a posterior approach, T12-L4. Baseline Hgb/Hct of 10/30. • Initial Concerns?

  12. Transfusion Requirements • Three Factors Predict Need for Transfusion • Age Greater than Fifty • Preoperative Hemoglobin Less than Twelve • TranspedicularOsteotomy • Ways to Decrease Intraoperative Blood Loss • Induced Hypotension • Operative Tables (Jackson & Wilson Frame) • Antifibrinolytic • Activated Factor VII • Cell Salvage • Hemodilution

  13. Which of the following antifibrinolytics has been shown to be the most effective in reducing blood loss? • Tranexamic Acid • Aminocaproic Acid • Aprotinin

  14. Antifibrinolytics • Aprotinin • Studies consistently show that it decreases blood loss • Withdrawn from the market after studies revealed a potential increase in mortality, perioperative renal failure, myocardial infarction and cerebral vascular accident after use • Study may have weaknesses • Tranexamic Acid & Aminocaproic Acid • Studies Inconclusive

  15. Case Three • 55 y/o male admitted for a lumbar spine surgery with a posterior approach. PMH is significant for peripheral vascular disease, diabetes and a prior TIA. The surgeon notes that the surgery will likely take ten hours and have an EBL of 2-3Liters. • Besides the likely need for transfusion, what is your first concern?

  16. True or False? Deliberate hypotension is associated with perioperative vision loss ? 1. True 2. False

  17. In spinal surgeries, the most common cause of postoperative vision loss is… • Cortical blindness • Posterior Ischemic Optic Neuropathy • Acute Angle Glaucoma • Anterior Ischemic Optic Neuropathy • Retinal Vascular Occlusion • Expansion of a vitrectomy bubble

  18. Post Operative Vision Loss Proposed Risk Factors of PION • Patient Factors • Male • Diabetes • Peripheral Vascular Disease • Operative Factors • Prolonged Duration in Prone Position • Large EBL • Anemia • Venous Congestion of Head • Hypotension • Prolonged Use of Vasopressors • Type and Amount of Fluid Replacement • Blood Transfusion • External Pressure?

  19. Case Four • A 27 y/o male s/p MVA is brought to the operating room for an emergent decompression for traumatic cervical spinal cord injury. • What is your initial concern?? • Securing the Airway

  20. True or False? A patient with a recognized, unstable cervical spine injury has an increased risk for neurologic injury following intubation. • True • False

  21. What is the best technique for securing the airway in an extremely unstable cervical spine? • Awake Fiberoptic • Direct Laryngoscopy • Fast Track LMA • Glidescope • Thoughts??

  22. What FiO2 has been associated with a higher risk of surgical site infection in spine surgery? During the case the surgeon asks you to modify your inspired gas concentrations to decrease the risk of a surgical site infection. • 1. no association • 2. < 30% • 3. < 50% • 4. < 70 % • 5 .< 90%

  23. Securing the Airway • Maintain neutral neck position • Greatest movement in the atlanto-occipital junction and the junction of the first two cervical vertebrae • If the patient has a recognized unstable cervical spine, intubation is not associated with an increased risk of neurologic deterioration • Superior Technique for Intubation? • Awake Fiberoptic, Direct Laryngoscopy, Glidescope, Fast Track LMA • All techniques are acceptable in experienced hands

  24. Case Control Study • Johns Hopkins, 2009 • 104 patients with surgical site infections compared to 104 random patients without surgical site infections • Compared multiple factors, including an FiO2>50 • FiO2 is a MODIFIABLE risk factor • 02 vital to oxidative leukocyte processes

  25. CASE SIXA patient is brought to the OR for an aortic dissection. The patient is on dabagatran. How should you reverse the anticoagulation? • Administer FFP • Administer Platelets • Administer Cryoprecipitate • Dialyze the patient • Administer protamine

  26. Dabigatran is a…. • 1. Direct Thromin Inhibitor • 2. GIIb/IIIa Inhibitor • 3. Platelet Aggregation Inhibitor • 4. Fibrinolytic Agent

  27. How long after the last dose of dabagatran should you wait before placing an epidural? • 8 hours • 10 hours • 24 hours • 34 hours • 72 hours

  28. Pradaxa (dabigatran) • Direct Thrombin Inhibitor • Alternative to warfarin for prevention of stroke, DVT • 80% renally excreted unchanged • Administered PO • Does not require INR monitoring • PTT is prolonged, but it is not linear and does not correlate to the level of anticoagulation • Ecarin clotting time most accurate

  29. Dabigatran & the Emergent Surgical Pt • Currently no way to fully reverse the anticoagulation • A monoclonal antibody is being developed • For active bleeding • Hemostasis • Transfuse as needed • Maintain diuresis (renally cleared) • Dialyze (62% can be cleared in 2 hours) • Factor VII? • One recent case report suggests a high dose of 7.2mg/kg may have helped reverse

  30. General Surgery • Half life 8 hours in a healthy patient • Half life up to 17 hours in patients with renal failure • Dabigatran should be stopped 1-5 days prior to surgery • Bleeding risk & type of surgery • Renal function of the patient

  31. Regional AnesthesiaNeuraxial Techniques & Direct Thrombin Inhibitors (2010 ASRA Practice Advisory) • ASRA: • Insufficient evidence. Suggest avoidance of neuraxial techniques. • German Society for Anaesthesia & • Belgian Association for Regional Anesthesia: • Needle placement 8-10 hours after last dose. Delay subsequent doses 2-4 hours after needle placement • American College of Chest Physicians: • No Recommendations • “Although there have been no reported spinal hematomas, the lack of information regarding the specifics of block performance and the prolonged half-life warrants a cautious approach.”

  32. Questions??

  33. References • Baldus, C. Can We Safely Reduce Blood Loss During Lumbar Pedicle Subtraction Osteotomy Procedures Using Tranexamic Acid or Aprotinin. Spine. 2010; 35: 235-239. • Barash, P. Clinical Anesthesia, 6th ed. 2009. • Bitar, W. Critical ischemia time in a model of spinal cord section. A study performed on dogs. European Spine J. 2007;16:563-572. • Black, Susan. PerioperativeManaement of Patients Undergoing Spine Surgery. Anesthesiology 2011. • Farrokhi, M, et al. Efficacy of Prophylactic Low Dose of Tranexamic Acid in Spinal Fixation Surgery: A Randomized Clinical Trial. J. of Neurosurgical Anesthesiology .2011;23:290-296. • Grottke, O, et al. Intraoperative Wake-Up Test and Postoperative Emergence in Patients Ungergoing Spinal Surgery: A Comparison of Intravenous and Inhaled Anesthetic Techniques Using Short-Acting Anesthetics. Anesthesia & Analgesia. 204;99:1521-7. • Jaffe, R. Anesthesiologist’s Manual of Surgical Procedures, 4th ed. Lipincott Williams & Wilkins, 2009. • Roth, S. Perioperative visual loss: what do we know, what can we do? British Journal of Anesthesia. 2009. 109; 31-40.

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