Positioning in neurosurgeries


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everything about positioning in neurosurgeries. combines the anaesthetic and surgical aspects

Positioning in neurosurgeries

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  2. 2. OUTLINE Why so much concern is involved Brief description of equipments Positions: physiology technique Free Powerpoint Templates Page 2
  3. 3. Its importance…. Proper positioning allows optimal exposure of thebrain Should be physically and physiologically safe for theanaesthetized patient We should be aware of its adverse effects on theoperation and on the patient Prolonged duration of neurosurgeries is to beconsidered Mistakes in this area cause PREVENTABLE injuries Knowledge improves our preparedness… Free Powerpoint Templates Page 3
  4. 4. OUR MAIN CONCERNS Raised intracranial pressure : causes may be ↑ intraabdominal pressure Kinking of IJV & venous congestion Head below the level of heart Free Powerpoint Templates Page 4
  5. 5. OUR MAIN CONCERNS Venous congestion : ↑brain swelling & ↑venousbleeding Insufficient abdominal bolstering ↑ PEEP Hyper rotation / flexion of neck Free Powerpoint Templates Page 5
  6. 6. OUR MAIN CONCERNS Airway compromise Hyperflexion  kinking of ETT Keep a distance one or two fingerbreadths betweenchin & chest during flexion Use armored tubes Free Powerpoint Templates Page 6
  7. 7. OUR CONCERNS Prolonged pressure on pressure points Stretching of nerves ; especially brachial plexus Corneal abrasions Thromboembolic complications Free Powerpoint Templates Page 7
  8. 8. HEAD UP For cranial procedures, almost invariably, somehead-up posturing [15-20⁰] is appropriate Exceptions:After evacuation of c/c SDH[↓Reaccumulation] After CSF shunting [to avoid too rapid collapse of ventricles] Free Powerpoint Templates Page 8
  9. 9. POSITIONING AIDS ANDSUPPORTS Pin (Mayfield) head holder Radiolucent pin head holder Horseshoe head rest Foam head support (e.g., Voss, O.S.I., Prone-View) Vacuum mattress (“bean bag”) Wilson-type frame Andrews (“hinder binder”)-type frame Relton-Hall (four-poster) frame Free Powerpoint Templates Page 9
  10. 10. PIN FIXATION DEVICESe.g. Mayfield head holder Skull block before application Placed in a band like area just above orbits & pinna[~sweatband] Avoid over thin temporal bone; caution when over frontalsinus Not < 3 years;3-10 years paediatricpins Coatedwith antibioticointment Free Powerpoint Templates Page 10
  11. 11. PIN FIXATION DEVICESe.g. Mayfield head holder Free Powerpoint Templates Page 11
  12. 12. PIN FIXATION DEVICESe.g. Mayfield head holder Clamp squeezed together, allowing the gears toslide, until the pins are seated in the skull Knob housing the tension spring & gauge istightened Each ring 20lbs; adult60-80 lbs ; pediatric: 30-40lbs Pediatrics: horse shoe is better Radiolucent pins if intraoperative CT/MRI used[minimal artefact ]e.g Titanium, Templates Free Powerpoint Macor,Silicon nitride Page 12
  14. 14. HORSESHOE HEADREST Free Powerpoint Templates Page 14
  15. 15. HORSESHOE HEADREST Free Powerpoint Templates Page 15
  16. 16. HORSESHOE HEADREST Free Powerpoint Templates Page 16
  17. 17. FRAMESSpinal surgery frames optimize venousreturnE.g. Relton-Hall[four-poster,Wilson andAndrew[hinder –binder] variantsrisk of air embolism + Free Powerpoint Templates Page 17
  18. 18. WILSONS FRAME Free Powerpoint Templates Page 18
  19. 19. SUPINE POSITIONPHYSIOLOGY Respiratory system: Cephalad push of diaphragm: ↓FRC by 1L, ↑closing volume [so alveoli closes at a volume very near to FRC,distal airways cant participate in gas exchange V-P mismatch], ↓COMPLIANCE Perfusion greatest in the dorsal aspect; Ventilation also. Why? Anaesthesia decrease FRC, increase closing volume,restricts and displaces diaphragm During controlled ventilation, abdominal contentsdecrease compliance of dorsal lung; so ventral lungreceives same perfusion, but more ventilation: HenceV-P MISMATCH Free Powerpoint Templates Page 19
  20. 20. SUPINE POSITIONPHYSIOLOGY Cardiovascular system ↑Venous return ↑CO  baroreceptor reflexes :↓HR,SV&CO/ atrial reflexes: act via RAAS/AVP/ANP Sympathetic tone ↓↓in HR,MAP& PVR[peripheral] SBP same; DBP ↓; so pulse pressure ↑ Anaesthesia, muscle relaxation and PPV interferewith venous return & autoregulatory mechanisms So circulatory effects of positioning may remainuncompensated in such patients Free Powerpoint Templates Page 20
  21. 21. Also note… Reverse Trendlenberg : increase in head and neckvenous drainage, reduction in intracranial pressure andreduced likelihood of passive regurgitation Elevation of the head 15 to 30 degrees will alsoencourage venous drainage Free Powerpoint Templates Page 21
  22. 22. SUPINE POSITION Head neutral / rotated Neutral Bifrontal craniotomy and transsphenoidalapproach to pituitary Flexed for interhemispheric approach to lateral orthird ventricle Slightly extended in subfrontal approach Free Powerpoint Templates Page 22
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  24. 24. SUPINE POSITIONprecautions Extremes of rotation can impair jugular venousdrainage; a shoulder roll can attenuate this problem Extreme flexion cause kinking of ETT Flexion + reverse Trendelenburg = ↑risk of VAE{esp. In bifrontal craniotomy which traverses SSS} Free Powerpoint Templates Page 24
  25. 25. SUPINE POSITION withHead Up Adjust table to a chase lounge (lawn chair) position FLEXION + PILLOW UNDER KNEE + SLIGHT REV TRENDELENBERG Promote venous drainage and decrease back strain Free Powerpoint Templates Page 25
  26. 26. Head is important; butdont forget others..Upper limbs usually @ the sidesDont abduct shoulder > 90⁰ [Brachial plexus] foam padding to elbow & wrist [ulnar and median n]Knee elevated [↓ tension on lower paert of back]Heels padded Free Powerpoint Templates Page 26
  27. 27. SEMILATERAL / JANETTAPOSITION * Supine position with a bolster For petrosal, retromastoid & U/L frontotemporalapproaches Lateral tilting of the table, 10-20⁰ with I/L shoulderelevated* Named after the neurosurgeon who popularized its use formicrovascular decompression of 5th nerve Free Powerpoint Templates Page 27
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  29. 29. SEMILATERAL / JANETTAPOSITION In petrosal & retrosigmoid approaches, elevatedshoulder pulled down inferiorly with tapeminimizeobstruction to view Shoulder bolster important in elderly patients withless flexible necks & to avoid kinking of IJV Extreme head rotation cause kinking of opposite IJVby the chin Excessive traction to shoulder stretch injury to Free Powerpoint Templatesbrachial plexus Page 29
  30. 30. LATERAL POSTION For access to posterior parietal and occipital lobesand lateral posterior fossa Includes C-P angle tumours and vertebral/basilaraneurysms Key feature: Use of axillary roll to prevent brachialplexus injury or pressure on dependent shoulder Rolls themselves can cause harm; prevented byplacement under the upper part of the chest rather than theaxilla Free Powerpoint Templates Page 30
  31. 31. LATERAL POSTION To maintain the lateral position a support placedalong the patients back and abdomen Knees flexed with paddings between the knees toavoid pressure over the fibular head and peronealnerve Free Powerpoint Templates Page 31
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  34. 34. LATERAL POSTIONphysiology RESPIRATORY SYSTEM: non dependent lung is wellventilated, but poorly perfused and dependent lung iswell perfused but poorly ventilated V/Q mismatch CVS: minimal decrease in MAP ; HR unchanged Free Powerpoint Templates Page 34
  35. 35. PARK-BENCH ORTHREE QUARTER PRONE POSITION Used in far lateral approaches placing the patient sufficiently superiorly on theoperating table such that the dependent arm ishanging over the edge of the table & secured with asling Trunk is rotated 15⁰ from lateral position into asemiprone position & supported with pillows. I/L shoulder is pulled inferiorly Free Powerpoint Templates Page 35
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  37. 37. PARK BENCH POSITION Head is flexed @ the neck and then rotated to looktoward the floor [120⁰ from vertical & laterally flexed20⁰ ] Free Powerpoint Templates Page 37
  38. 38. PARK BENCH POSITION Support the dependent arm Pad all pressure points Axillary roll placed under dependent chest Avoid too much tension on shoulder[Brachial plexus] Considerable rotation & flexion of the neckkinkingof ETT, IJV ( use Flexometallic ETT ) Excessive flexion prees mandible onto clavicle Free Powerpoint Templates Page 38
  39. 39. PRONE POSITION For spinal cord, suboccipital approach/occipital lobe,craniosynostosis and posterior fossa procedures Can cause hemodynamic changes, impairement ofventilation and spinal cord injury Anaesthesiologist should have a plan for detachingand reattaching monitors in an orderly manner toprevent excessive monitoring ‘window’.Needs coordination of members. Free Powerpoint Templates Page 39
  40. 40. PRONE POSITION The prone position also has been referred to, aptly,as the Concorde position because, for cervical spineand posterior fossa procedures, the final positioncommonly entails neck flexion, reverse Trendelenburg,and elevation of the legs. This orientation brings thesurgical field to a horizontal position. Free Powerpoint Templates Page 40
  41. 41. AWAKE PRONATION For patients with compromised spinal canal andwhen there is possibility of worsening of neurologicfunction with handling Patient can indicate pain Progression of Neurological deficit: YES / NO If progression, can correct the faulty position Needs adequate sedation and topical anaesthesia Free Powerpoint Templates Page 41
  42. 42. PRONATION AFTERINDUCTION Free Powerpoint Templates Page 42
  43. 43. PRONE POSITIONHow to achieve Patient placed on two bolsters or a support devicewith arms to the side of the body bolsters should be sufficiently far apart; To avoid compressing abdominal & femoral venous return To allow adequate diaphragmatic excursion Free Powerpoint Templates Page 43
  44. 44. PRONE POSITIONHow to achieveMove the trolley parallel & adjacentto operating table All lines:ensure length & secure 2 assistants stand on free side of table & another 2 on free side of trolley. One manage feet If cx spine is stable; anesthetist manage head & coordinate turn; if unstable neurosurgeon Keep arms of the patient alongside the body Free Powerpoint Templates Page 44
  45. 45. PRONE POSITIONHow to achievedisconnect lines / monitoring leadsand secure @ the signal from the person managing head, disconnect patient from anaesthesia machine turn him gradually onto the outstretched arms of the receiving assistants hold the arms alongside the body & head in the sagittal plane during turn Reconnect , auscultate the chest and confirm ETT position Free Powerpoint Templates Page 45
  46. 46. PRONE POSITIONHow to achievepatient remains supported byappropriate chest rolls rolls should support the lateral edge of the torso from head to foot Rotate head toward the anaesthesia machine & place it on a headrest Take care of the downside eye and ear Arms alongside / in front of the patient Free Powerpoint Templates Page 46
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  50. 50. PRONE POSITION breast & genitalia placed medially between chest rolls Eyes taped; head supports should be spaced wide enough ; pin based holder better Down side ear kept flat and unfolded Chin is tucked in the suboccipital approach 2 FB distance between chin-mandible,sternum-clavicle no pressure over pre auricular area; VII n superficial Free Powerpoint Templates Page 50
  51. 51. PRONE POSITION Ensure even pressure over face / Intermittently check for orbital compression Arms and knees padded Ankles elevated so that toes are hanging freely A rolled gauze bite block instead of an oral airway can avoid compression ischemia while preventing trapping of tongue in between teeth Free Powerpoint Templates Page 51
  52. 52. PRONE POSITIONCARDIOVASCULAR SYSTEM CVS adapts well Venous pooling may reduce cardiac filling pressuresand cardiac output Improper position- obstruct femoral vein / IVC ;↓BP/venous return wrapping legs with elastic / pneumatic stockings canmaintain the filling pressures Free Powerpoint Templates Page 52
  53. 53. PRONE POSITIONRESPIRATORY SYSTEM If allowed to breathe spontaneously, has to movethe entire thoracic mass off sternum to expand pleuralcavity ; also weight of dorsal trunk push abdominalcontents cephalad ,which push diaphragm↑ WOB If rolls correctly placed, chest and abdomen hangfree; ventilation accoplished with normal pressures FRC decrement seen in supine position is not seenwith prone position Free Powerpoint Templates Page 53
  54. 54. PRONE POSITIONCENTRAL NERVOUS SYSTEM Vertebral venous plexus have anastomoticconnections with IVC & femoral vein Compression of IVC diversion of blood to vertebralvenous plexus  ↑ bleeding, ↓visibility in spine surgery Free Powerpoint Templates Page 54
  55. 55. IF PROPERLY POSITIONEDON CHEST ROLL Free abdomen ↓barotrauma = less motion . Less CSF flux Less bleeding Free Powerpoint Templates Page 55
  56. 56. TAKE CARE OF BRACHIAL PLEXUS In ‘stick-em up’ position arms shouldnt be abducted>90⁰; elbows shouldnt be extended>90⁰ [90-90position] Elbow should be anterior to the shoulder to preventwrapping of brachial plexus around head of humerus Pronation makes ulnar nerve very vulnerable, whilesupination keeps it in a more protected position Free Powerpoint Templates Page 56
  57. 57. DONT loose YOUR TAPE TO SALIVA… Ensure fixity of ETT tape •ANTISIALOGOGUE •BENZOIN- ADHESIVE Free Powerpoint Templates Page 57
  58. 58. When a thing ceases to be a subject of controversy, itceases to be a subject of interest…William Hazzlit ….SITTING POSITION Free Powerpoint Templates Page 58
  59. 59. SITTING POSITION Several reviews of large experiences concluded thatthe sitting position can be employed with acceptablerates of morbidity and mortality Access to midline structures like floor of 4thventricle, pontomedullary junction and vermis better;for supracerebelar infratentorial approach Better anatomic orientation, better visualization forthe assistant, drier field Sitting Vs Alternatives risk Vs no risk Free Powerpoint Templates not like that! Page 59
  60. 60. Will you prefer….in…? Patient with poor cardiac reserve Patient with ventriculoatrial shunt Known intracardiac defects Pulmonary A-V malformations Severe hypovolemia / cachexia Severe hydrocephalus Lesion vascularity ………..NO…NO Free Powerpoint Templates Page 60
  61. 61. HOW TO ACHIEVE.. Skull secured in three pin head holder [applied while onsupine] Infiltration of scalp & periosteum @ pin sites[↓hypertesive response] Arterial pressure transducer zeroed @ the interauralplane1 /skull base2 [CPP maintenance become easier] Bony prominences well padded Legs placed in thigh-high compression stockings Free Powerpoint Templates Page 61[limit pooling of blood] But it’s not a tourniquet….understood?!
  62. 62. HOW TO ACHIEVE Elbows supported by pad/pillows to avoid contactwith table or U-frame or stretch on brachial plexus Legs freed of pressure [@ the level of common peronealnerve just distal & lateral to head of fibula;Pillow under knees] At least 1 inch / 2 fingerbreadth space between chin &chest [to prevent cervical cord stretching & venous obstruction] Avoid large airways & biteblock in the pharynx Free Powerpoint Templates Avoid excessive neck rotation, especially in elderly 62 Page
  63. 63. HOW TO ACHIEVE Avoid excessive flexion of knees towards the chest[prevent abdominal compression,lower extremity ischemia andsciatic nerve injury] Head holder should be attached to the back portionof the table, rather than to the thigh portion [makes lowering of head and closed chest massage ifnecessary, easier] Free Powerpoint Templates Page 63
  64. 64. SEQUENCE While monitoring BP, adjust the operating table Flex the table fully & lower the foot section 45⁰ Slowly elevate back section while placing the chassis inthe Trendelenberg position Free Powerpoint Templates Page 64
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  66. 66. SEQUENCE Raise the back further untill the desired sittingposition is achieved Finally adjust foot section of the table to horizontalposition Free Powerpoint Templates Page 66
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  68. 68. SEQUENCE Remove head rest and attach skull clamp to a Ushaped frame which has been attached to operatingtable Adjust U-frame & skull clamp to get the desired neckflexion and head position Free Powerpoint Templates Page 68
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  71. 71. HOW TO ACHIEVE its like a modified recumbent position rather thantruly sitting Lateral lesions: a ‘lounge chair’ modification, withthoracic cage raised to 30-45⁰ ‘lateral sitting position’ allows rapid head lowering tothe left lateral decubitus & continiuation of theoperation in the vent of hypotension or persistent VAE After positioning apply precordial doppler/ TEE withpediatric / small probe Powerpoint Templates Free Page 71
  72. 72. The tense anaesthetist VAE..?has some advantages… Lower airway pressures Ease of diaphragmatic excursion Improved ability for hyperventilation Better access to the ET tube & thorax for monitoring Easier access to extremities for monitoring/ fluid orblood administration / sampling Can see face during cranial nerve stimulation Free Powerpoint Templates Page 72
  73. 73. NOTE…. Improved post operative cranial nerve function hasbeen reported in patients undergoing acousticneuroma resection in the sittin position, than in thoseoperated in the horizontal position* *Black S, Ockert DB, Oliver WC Jr, et al. Outcome following posterior fossacraniectomy in patients in the sitting or horizontalpositions. Anesthesiology 1988 69:49-56 Free Powerpoint Templates Page 73
  74. 74. PHYSIOLOGY Head elevation above RA↓ dural sinuspressure[90⁰position cause a↓upto 10 mm of Hg] ↓ venousbleeding increase risk of VAE N.B. jugular bulb venous pressure is not a reliableindicator of dural sinus pressure Free Powerpoint Templates Page 74
  75. 75. PHYSIOLOGYCARDIOVASCULAR SYSTEM Free Powerpoint Templates Page 75
  76. 76. PHYSIOLOGYCARDIOVASCULAR SYSTEM Free Powerpoint Templates Page 76
  78. 78. PHYSIOLOGYCARDIOVASCULAR SYSTEM Anaesthetic drugs and the sitting position acttogether so that the physiological insult is morepronounced…So watch B.P. closely. Adequate relaxation to prevent dangerousmovement Depth titrated for optimal haemodynamic response Rx hypotension promptly by vasopressors, adjustingdepth and IVFs Free Powerpoint Templates Page 78
  79. 79. PHYSIOLOGYCARDIOVASCULAR SYSTEM A pulmonary arterial catheter if h/o CAD,Valvulardisease or >60 years all patients should be preoperatively imaged with anecho to R/O patent foramen ovale CPP should be maintained @ a minimum of 60 mm ofHg Free Powerpoint Templates Page 79
  80. 80. PHYSIOLOGYRESPIRATORY SYSTEM FRC & VC improved Hypovolemia may decrease upper lung perfusion V-P mismatch / hypoxia Volatile agents may increase transpulmonary passageof air N2O contraversial Free Powerpoint Templates Page 80
  81. 81. References Essentials of Neuroanaesthesia & Neurointensive Care; Arun K. Gupta and Adrian W. Gelb (2008) Neuroanaesthesia Handbook; David J Stone, Richard J Sperry,Joel O Johnson Miller’s Anaesthesia 7/e (2010) (1)P:2053 Cottrell and Young’s Neuroanaesthesia 5/e (2010) Patient positioning in anaesthesia (2)P:204 David JW Knight,Ravi P Mahajan,BJA,CEACCP vol 4,issue 5p:160- 163 Practical Handbook of Neurosurgery: From Leading Neurosurgeons, Volume 3,By Marc Sindou Free Powerpoint Templates Page 81
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