Anesthesia for spinal cord injury and scoliosis030


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Anesthesia for spinal cord injury and scoliosis030

  1. 1. Anesthesia for Spinal cord injuryand scoliosisAtef KamelMD
  2. 2. BackgroundAnatomy & PhysiologyPathophysiologyPharmacologyAnesthetic Technique & ManagementManagement of ComplicationsCase Study
  3. 3. Anatomy & Physiology
  4. 4. Anatomy and physiol
  5. 5. Blood Flow to the Spinal CordAnterior Spinal Artery (1) Anterior 2/3 of spinal cordPosterior Spinal Arteries (2) posterior 1/3 of spinal cordThese 3 arteries depend on a network of collateral vessels to provide adequate blood supply to the spinal cord.
  6. 6. Artery of Adamkiewiczarteria radicularis magna Largest most consistent radicular artery Located in the thoracolumbar region (T5-L3) Supplies blood to the ASA (anterior 2/3 of cord) Responsible for most of the spinal cord blood flow beneath its point of entry If obstructed  Anterior Artery Syndrome
  7. 7. Spinal Cord Blood FlowAutoregulation determines the amount of blood flow to the sp cd.Limits: 50-150 mmHg. Outside these limits pressure dependant.Spinal cord blood flow increases when CO2 levels are high and decreases when CO2 levels are low. (similar to cerebral blood flow)Injury to the spinal cord alters both autoregulation and CO2 responsiveness.
  8. 8. Pathophysiology
  9. 9. Spinal Cord InjuryTrauma  Partial or Complete transection of the cordTransections above C 3-5 = Diaphragmatic innervention (ventilator required for survival)Transections above T 1 = QuadraplegiaTransections above L4 = ParaplegiaMost Common C 5-7 & T 12 - L 1 (least protected / most mobile)
  10. 10. Acute Spinal Cord InjurySpinal shock may begin within an hour after injury and last from several minutes to several months, after which reflex activity gradually returns: Flacid paralysis Complete loss of reflex and sensory activity below level of lesion. Loss of vasomotor tone, CV instability, Hypotension, Bradycardia, Venous pooling. Paralytic ileus with distension Hypothermia
  11. 11. ScoliosisLateral curvature of the spine, usually accompanied by rotation.Cobb angle is a method used to measure the curvature.The greater the angle, the greater the progression and severity of complications.
  12. 12. Causes of Scoliosis Neuromuscular Scoliosis - the result of muscle imbalance and lack of trunk control. (i.e. cerebral palsy, muscular dystrophy, or leg length discrepancy) Congenital Scoliosis - the result of asymmetry of the vertebrae secondary to congenital anomalies. (i.e. hemivertebrae, failure of segmentation) Idiopathic Scoliosis - no definite etiology. Diagnosis of exclusion. Most common type accounting for 80-85% of cases
  13. 13. Effects of scoliosis  Increased curvature = narrowing of thoracic cage, which leads to abnormal CV and Pulm function.  Increased curvature causes increased co-morbidities  Restrictive lung disease, dyspnea on exertion, pulmonary hypertension, cor pulmonale and alveolar hypoventilation.
  14. 14. Respiratory AbnormalitiesLung volumes reducedCompliance decreasedRestrictive patternAbnormal V/QShallow, rapid breathingAlveolar hypoventilationHypoxemia
  15. 15. PROGRESSION OF RESPIRATORY DISEASE WITHINCREASING DEGREE OF SCOLIOSIS < 10 normal > 25 increased PA pressures > 40 surgery considered > 65 restrictive lung disease > 100 exertional dyspnoea > 120 alveolar hypoventilation
  16. 16. NEUROMUSCULAR SCOLIOSIS – severe respiratorydysfunctionweak resp musclesineffective cough, unable to clear secretionsincoordinate swallowing, impaired airway defencesimpaired central resp driveexaggerated resp depressant effect of drugsimmobile, retain secretionsrecurrent chest infections
  17. 17. CARDIOVASCULAR ABNORMALITIESPulmonary HypertensionChronic hypoxiaReduced flow through compressed lungImpaired development of pulm vasc bedCor PulmonaleCardiac Failure
  18. 18. Other Cardiovascular AssociationsIdiopathic scoliosis - mitral valve prolapseMuscular dystrophy - cardiomyopathy, arrhythmiasMyotonia - dysrhythmias, conduction abnormalities, mvp
  19. 19. Pharmacology
  20. 20. Spinal Cord Injury & SuccinylcholineSuccinylcholine- Induced Hyperkalemia.Safe to administer Succs within first 48 hours after spinal cord injury.Avoid Succs in all spinal cord injuries after 48 hours
  21. 21. Epidural Steroid Injections Methylprednisone 80 mg (smaller amounts in diabetics who may be at increased risk for formation of epidural abscess) is injected into epidural space close to the nerve root. The addition of 3-4 mL of local anesthetic (lidocaine) to the injected solution produces analgesia, confirming proper drug placement
  22. 22. Epidural Steroid Injection
  23. 23. Epidural Steroid Injection (cont.)Few pts get relief from repeated injections if first one was unsuccessful.Relief can last from weeks to months - injections are repeated every 3-4 months.Little risk of serious complications ; Aseptic meningitis and bacterial meningitisAdrenal Suppression may occur but recovers in 1-3 months.
  24. 24. High Dose Steroid Therapy(methylprednisone)Acute Spinal Cord InjurySevere spine disease undergoing major spinal surgery.Recommendation = bolus dose of 30 mg/kg over 15 minutes, then 5.4 mg/kg/hr for 23 hrs, within 8 hours of injury.If therapy is started 8 hours after injury, the duration of the methylprednisone therapy should be continued for 48 hoursPitfalls = Immunosuppression,wound infections & GI bleeds.
  25. 25. Tricyclic Antidepressants• Useful for chronic pain, producing analgesic effect via inhibition of reuptake of serotonin and norepinephrine.• Other benefits include: normalization of sleep patterns, reduction in anxiety and depression.
  26. 26. AnticonvulsantsMay have some efficacy in treatment of chronic pain syndromesChronic anticonvulsants lead to an increased resistance to non-depolarizing neuromuscular relaxants
  27. 27. Anesthetic Technique & Management
  28. 28. Management of Spinal Cord InjuriesImmediate management is critical.Improper handling can cause further damage and loss of functioningAlways assume there is a spinal cord injury until it is ruled outImmobilizePrevent flexion, rotation or extension of neckAvoid twisting patient
  29. 29. Management cont’d• Management is aimed at preventing further injury and observing for progression of neuro deficits• Consists of emergency treatment following an A-B-C-D-E sequence.
  30. 30. Airway ManagementFirst priority.Open airway with jaw-thrust maneuver.Use bag-valve-mask device initially, if necessary intubate.High conc. of 02 will prevent bradycardia or asystole for patients exhibiting signs of neurogenic shock.
  31. 31. BreathingLesions above C5 level will cause partial to complete diaphragmatic paralysis (diaphragm is innervated at C3-5 levels).Lesions at C5 and below will allow full diaphragmatic movement, but intercostal muscles (innervated at T1) and abdominal muscles (innervated at T12) are affected.
  32. 32. CirculationCardiac output is affected by external or internal hemorrhage and neurogenic shock.IV fluidsBlood transfusionVasopressors
  33. 33. DisabilityNeurological ExaminationLateral C-Spine X-rayCT scanSearch for other injuries: abdominal, chest, …
  34. 34. Anesthesia Implications forAcute Spinal Cord Transection In-line stabilization of neck. Consider fiberoptic intubation, especially if cervical spine injury is suspected. Prepare for CV instability, position changes, mild blood loss, .. Guard against hypothermia. Succinylcholine may be administered within the first 24 hrs of acute injury Blood flow (maintain perfusion pressure, normal CO2) SSEP, MEP, wake up test
  35. 35. Anesthesia Implications forChronic Spinal Cord TransectionMonitor for autonomic hyperreflexia. Have rapid-acting vasodilators available.Bradycardia / absence of compensatory tachycardia (cardioaccelerators T1-4).Use nondepolarizing muscle relaxants only.Guard against hypothermia.Position carefully (osteoporosis).
  36. 36. Autonomic HyperreflexiaSympathetic system reflex response below the level of a spinal cord transection.At T5 or above.After the resolution of spinal shock.Triggers : stimulation below the level of injury.
  37. 37. Autonomic hyperreflexiaS/S = HTN, reflex bradycardia, seizure, SAH, PE, VD/ flushing above transection & VC/ pallor below transection.Treatment: Remove noxious stimulus, Raise head of bed, Administer rapid-acting vasodilator drugs.
  38. 38. Anesthesia for scoliosis
  39. 39. Pre-operative EvaluationHistory & examination - type of scoliosis, assoc. problems ( neuromuscular, airway, GIT, MH, latex allergy), resp and cardiacCXR , ECG, Blood testsSpine Xray – severity & locationEchoLung Function Testing (if severe deformity)Lung volumes (>40% reduction ~ post-op complics)Flow volume loopABG
  40. 40. Preoperative preparationClear chest infection .Wake up test explaining.Posibility of post operative mechanical ventilationPremedication: atropine? Heavy sedation should be avoided in severe scoliosis.?
  41. 41. Anesthetic Problems associated withScoliosis SurgeryProblems related to the patient: Respiratory , cardiovascular neuromuscular abnormalities or syndromes.
  42. 42. Problems related to the surgeryProne positionBlood loss and third space loss: solution?Lengthy operationPreservation and monitoring of spinal cord function.Heat loss.??Postoperative visual loss.
  43. 43. MonitoringRoutine monitors: oximeter, ECG, capnography, esophageal stethoscope and core body tempArterial catheter to monitor beat to beat changes.CVPUrinary catheterBlood loss and replacement are monitored.Patient’s position
  44. 44. Induction of anesthesiaTwo large IV linesSuxamethonium. is avoided in paralyzed patients or neuromuscular etiology.Intermediate non depolarizing ms. relaxent like Atracurium or Rcuronium is used for intubation and maintenance of relaxation.
  45. 45. Prone position
  46. 46. Prone positionMaintain alignment of head / neck, support head in neutral position w/ pillow or head holding device.Avoid hyperextension of arms by tucking them against the body or extending them <90 degrees alongside the head on armboardsCompression stockings to avoid the pooling of blood.Frequently examine eyes, ears, chin, nose, shoulders, breasts, and genitalia for areas of pressure.
  47. 47. Spinal Cord ProtectionMethylprednisoloneReestablish normotension, normooxia and normocarbia to avoid secondary insult.Instruct surgeon to decrease traction on spinal cord.Monitoring of the spinal cord: wake up test, SSEP and MEPs
  48. 48. Post Op Visual Loss -POVLUnkown Cause, may Risk Factors: hypoperfusion +edema  Hypotension +stretching of the optic  Anemia nerve.  GlaucomaLong prone cases  Preventative measures:  Keep IV fluid to reasonableLarge amounts of IV level fluid.  HCT > 27  MAP >70 mmHg  Avoid pressure on globe
  49. 49. SPINAL CORD MONITORINGThe Wake Up Test: 2 assisstants Monitors motor function, simple to performProblems - extubation/lines/hardware, air embolism, awareness, false neg.Containdications – paresis, uncoop.Modified for use in small children (withdrawal to tetanic stimulus)
  50. 50. SOMATOSENSORY EVOKED POTENTIALSContinuousSensory tractsLatency (> 0.2msecs)Amplitude (> 50% decrease)Cortical or Spinal
  51. 51. MOTOR EVOKED POTENTIALSMEP is basically an EMG potential recorded over muscles in the hand or foot in response to depolarization of the motor cortex using transcranial stimulus.MEP profoundly affected by anesthetic agents, recordable only during TIVAMEP cannot be recorded in the presence of complete neuromuscular blockade.
  52. 52. Extubation of the patientExtubation may be performed immediatelyExtubation in the ICU
  53. 53. Indications for postoperative mechanical ventilation:VC was < 30% of predicted.Severe gas exchange abnormality (↑PaCO2).Duchenne muscular dystrophy.Severe CP.Patient with congenital heart.Severe face edema.PaO2 on mask ↓70 mmHgRespiratory rate > 35 breath /min.
  54. 54. Post operative carePulmonary care.Fluid management.Pain control. How?Laboratory studies.
  55. 55. Case Study29 ys male pt. 110 kg. 9 days s/p MVA SCI. hx = asthma, donated one kidney.Planned surgery is a C1-3 Cervical fusion. dx: occipitoatlantal instability?
  56. 56. Pre OpMonitorsInductionMaintenanceEmergencePost Op
  57. 57. QuestionAll of the following are potential risk factors for POVL except for 2 of the following.• A. Obesity• B. Long Prone Cases• C. Anemia• D. Pressure on the globe• E. Hypotension• F. Glaucoma• G. Cataracts
  58. 58. Question• Paraplegia is the result of which of the following injuries?• A. Occlusion of the artery of adamkiewicz• B. Spinal cord transection at C7• C. Spinal cord transection at L2• D. A & C are both correct• E. All of the above are correct