management of kyphoscoliosis intraoperative management neuromonitoring in spine surgery

1. Guide- Dr MADHEKAR MA’AM
STUDENT- DR ASHISH NAIR
AANA journal/August2007/Vol.75,No.4(277-85)
ATOTW 397 — Introduction to Intraoperative Neurophysiological
Monitoring for Anaesthetists (5 February 2019) Page 1 of 11

3. OVERVIEW
 Anatomy and definition
 History
 Types
 Prevalence
 Signs & symptoms
 Severity and Cobb’s angle
 Effects of kyphoscoliosis on various organ systems
 Surgical correction
 Preoperative evaluation
 Management of anaesthesia

4. DEFINITION
• Kyphoscoliosis describes anabnormal curvature of thespine
inboth coronal andsagittal plane
• Kyphosis is acurving of thespine thatcauses a bowing of
the back
• Scoliosis is definedasalateralrotation of the spine greater
than10 degrees accompanied by vertebral rotation
 Scoliosis involves:
I. lateral curvature of spine
II. Vertebral body rotation
III. Angulation of the ribs leading to thoracic rib cage
deformity

5. HISTORY
 5th century – HIPPOCRATES described
 Galen(AD 131-201) termed scoliosis
 Galen also used chest binders to aid spinal curvature
 Pare (1510-1590) developed iron corsets
 Jules Guerin(1839)- first surgical Rx
 Sayre(1880s)-POP in vertical suspension device
 Lange(1902)-spinal fusions in TB kyphosis
 Hibbs(1914)- spinal fusion for scoliosis
 Harrington(1955)-distraction rods for Rx of scoliosis in
polio
 Luque(1970s)-used Harrington or Luque rods for spine
fixation(now currently used) aka Cotrel-Dubousset rods

6. TYPESOF SCOLIOSIS
 1.IDIOPATHICSCOLIOSIS-MOST common type(70%) Cause
unknown
 Classified by age of onset
 Types:-
a) Infantile
b) Juvenile
c) Adolescent

7. 2. NEUROMUSCULAR SCOLIOSIS(PARALYTIC
SCOLIOSIS)
Neuropathic
 Upper motor neuron(CP, spinal cord injury)
 Lower motor neuron(poliomyelitis,meningomyelocele)
Familial dysautonomia
 Others(syringomyelia)
Myopathic
 Progressive
(Muscular dystrophy)
 Static(amyotonia
congenital)
 Others(freidrich’s
ataxia)

8. 3.CONGENITAL
SCOLIOSIS(with/without neuro
deficit)
 Open,with posterior spinal defect
 Closed,no posterior element defect
i. -Abnormality of development of vertebrae –
hemivertebrae/congenitally fused ribs
ii. -½ cases associated with other organ system abnormalities
4.Neurofibromatosis
5.Mesenchymal disorders
 congenital-Marfan’s syndrome, morquio syndrome,Ehlers Danlos
syndrome
 Acquired- rheumatoid arthiritis, still disease
 Others-osteogensis imperfecta
5.Trauma
 Vertebral-fracture,surgery, Post radiation
 Extravertebral-Post thoracoplasty, burn

9.  Mc form is- adolescent idiopathic scoliosis(AIS)
 Children between age of 10-16 yrs
PREVALENCE
• Curves >10° :1.5 – 3% ofpopulation
• Curves >20° :0.3 to 0.5%
• Curves >30° :0.2 to 0.3%
• Most curves convex to the right
• Males are more likelyto have infantile/juvenile
scoliosis
•Females-adolescent scoliosis

11. KYPHOSCOLIOSIS

12. TYPESOF KYPHOSIS
• Postural kyphosis
– most common type
• Scheuermann's kyphosis
– aform of juvenileosteochondrosis of the spine
• Congenital kyphosis
• Nutritional kyphosis
– Vit D deficiency
• Gibbus deformity
– Tuberculosis
• Post-traumatic kyphosis

13. ASSOCIATED CONDITIONS
• Cerebral palsy
• Cerebral muscular dystrophy
• Spina bifida
• Duchenne’s muscular dystrophy
• Familial dysautonomia
• Friedreich’s ataxia
• Skeletal dysplasia
• Marfan’ssyndrome
• Neurofibromatosis
• Connective tissue disorders
• Craniospinal axis disorders :syringomyelia

14. ADOLESCENT IDIOPATHIC SCOLIOSIS
 Mc deformity of spine
 Near onset of puberty
 Lateral curvature and vertebral rotation of more than 10
degree
 1-3%incidence in adolescents(10-16yrs)
 Females more affected than males
 Ratio 3.6 to 1
 spinal bracing can slow progression and prvent need for
surgery
 4 curve patterns –thoracic,lumbar,thoracolumbar,double
major curves

15. SIGNSANDSYMPTOMS
• Back pain
• Leg length discrepancy
• Abnormal gait
• Uneven hips or waist
• One shoulder higher than other
• Prominent shoulder blade.
• Appearance of leaning to one side
• Increased space between the body and
the elbow while standing in natural
posture.
• Chest/rib prominence.

17. PHYSICALEXAMINATION
• Feetfor cavovarus
deformity
• Muscle tone – spasticity
• Gait
• Thorough neurological
exam

18. ASSESSMENT OF SEVERITY
 Cobb’ s angle(1948)
• Tomeasure coronal plane
deformity on antero-posterior
planeradiographs in the
classificationof scoliosis
• Determining severity of
disease

19. MEASUREMENTOFTHECURVE INSCOLIOSIS USINGCOBB'S ANGLE
• Identify the
upper and lower
end vertebrae
• Draw lines
extending along the
vertebral borders.
•Measure the cobb
angle(5)
The cobb angle is derived from the angle between intersecting lines drawn
perpendicular to the top of the uppermost affected vertebra and the bottom of
the lowermost affected vertebra.

20.  The degree of spinal curvature at skeletal maturity aids
in predicting the magnitude of curve progression for
the lifetime of the patient
 Weinstein et al
<30 deg- minimal disease progression
>30 deg – progression of 19 deg in life span
>50 deg – 1-2 deg progression per year
Surgery is indicated @ 40-50 degree
 “Double curve patterns of the thoracic and lumbar
spine are more likely to progress than single curve
patterns “
 “Larger curves have greater risk of progression”

21. COBB’ S ANGLE
 Greaternumberofvertebrae involved
 More cephaladlocationof curve
 Loss ofnormalthoracic kyphosis
 Neuromusculartypes
Scoliosisseverityincreases with:-

22. RISSER FERGUSON METHOD

23. • Stand erect with feettogether &knees fullyextended & palms
touching each other
• Bending forward until back is horizontal
• Asymmetry of thoracic or lumbar spine maybe detected with
Scoliometer
• Measure Angle of Trunk Rotation(ATR) atthoracic,thoraco
lumbar &lumbar areas of spine
ADAMS FORWARDBENDTEST

24. TREATMENT
• Surgical intervention occurs when the curve magnitude estimated by the
Cobb methodis morethan40 degrees
• Fusevertebraeinamore normalcurve
• Severecurves:leadingto cardio-respiratory compromise
• AIM :to achievespinalfusionincorrected position
 – Decortication &maintainingcorrection till bonyfusionwith
thehelpof instrumentation
• Erector spinae,spinousprocess,intraspinal ligament,facetjoint
removed
• Vertebraedecorticated&bonegraft placed

25.  Flexible thoracic curve(without lumbar curvatures)-
posterior spinal fusion with instrumentation
 Stiff thoracic curve-anterior approach is required
- gains spinal mobility
- improve posterior correction
 Thoracolumbar curves- more challenging
- increased manipulation
- increased surgical time
- increased blood loss
- increased risk of neuro. complications

26. SURGICALOPTIONS
 Posterior correction & instrumentation
 Herringtonrod
 Cotreldubousset instrumentation
 Anterior correction &instrumentation
 Thoracotomy
 Transdiaphragmatic
 transabdominal
 Anterior release/fusion&posterior instrumentation
 Posterior release/fusion&anterior instrumentation
 Combined anterior &posterior instrumentation &fusion

27. EFFECTSOFKYPHOSCOLIOSIS
ON
VARIOUS SYSTEMS

28. RESPIRATORY SYSTEM
 Cobb’s angle >50 deg at skeletal maturity
 Reduces the mechanical efficiency of the chest wall- restrictive
lung disease
• Restrictive pattern is seen- ↓↓vital capacity(60-80% of
predicted)
• As the thoracic curvature increases- VC(max),FEV1,PaO2 ↓
↓TLC,↓FRC,↓IC,↓ERV.
↓IC with normal expiratory flow results in diminished FEV1 and
FVC but the FEV1/FVC ratio remain normal
• During exercise the ventilation is adequate but there is ↓TV and
↑RR the maximum work capacity decreases.
• Cobb’s angle 70-100 deg -> severely restrictedventilation
->alveolar hypoventilation ->AV shunting -> cor pulmonale

29.  A preoperative vital capacity of less than 35% is considered a
relative contraindication for surgery.
 “thepresence of an adequatecoughis agoodclinical indicator of a
satisfactoryforcedexpiratoryvolume.”
 PFT
pulmonary function is most closely related
- to Cobb angle
-number of vertebra involved in the scoliosis curve
-location of the upper-most vertebra
-patient age
CauseofabnormalPFT
• Due to abnormalthoraciccagegeometryleadingto marked
decreaseinchestwall compliance
 thelungsandrespiratorymusclesarenormal exceptin
congenitalandinfantiletypewherethe growth ofthelungsmay
be impaired.

30. BLOOD GAS ABNORMALITYIN SCOLIOSIS
• Arterial hypoxemiaismainlybecauseofventilationperfusion
mismatch.(ArterialO2 desaturation)
• pCO2 andpH arenormal(initially)
↓ diffusingcapacityandalveolarhypoventilationmay contribute.
• Severelongstandingscoliosis isa/wmarkedV/Q mismatch,
alveolarhypoventilationandCO2 retention.(hypoxemia,hypercapnia,
secondaryelectrolyteabberations)
• ifnot surgically treatedmayleadto PAH and respiratory failure.
•Symptoms of upper and/or lower respiratory infection should prompt a
thorough examination.
•Anesthetists and surgeons may want to consider postponing the surgery
for 4 to 6 weeks to allow full recovery from th e respiratory infection.

31. Cardiovascular system
• Maybeassociatedwith↑pulmonaryvascularresistanceand
pulmonary hypertension.
•MayresultinRVH andRightventricular failure.
•Cause- hypoxemia→pulmonaryvasoconstriction → ↑PVR →
 ↑PA pressure.
•Chronic hypoxemia→PAH.
•Hypoxic pulmonary vasoconstriction takes place in the face of
reduced PaO2
• A/wwithmitralvalveprolapse.Antibioticprophylaxisbefore
catheterization&laryngoscopy
Cardiomyopathy-Duchenne’smuscular dystrophy
Mitral/aortic insufficiency-Marfan’s syndrome
Congenital heartdiseaseis common.

33. PREOPERATIVE EVALUATION
Nature of spinal curve
• Locationofcurve-thoracicscoliosisisa/w↑PFT abnormalityandcervical
scoliosiswithdifficult airway.
• Age ofonset-earlyonsetscoliosismaybe a/w
 ↓alveolarnumberandimpairedgas exchange.
• Severity->60 relatedto decreasepulmonary functionand>100to
impairedgasexchange.
• Etiology-maybea/wother diseases.
•H/O SOB, DOE andefforttoleranceto assesthe cardiopulmonaryreserve.
•H/O coughor wheezeto seeassociationwithany parenchymallung disease.
•Ptofmarfan’sandneurofibromatosismayhave symptomsofpalpitationsand
syncopebecauseof underlyingcardiac conditions.
HISTORY

34. Physical examination
o Auscultation of lungs for anywheeze(obstructive or
parenchymallung disease)
o Heart-signs of PAH(loud P2)and signs of
RVH(engorged veins,hepatomegaly,edema)
oSkin-caféaulaitspots in NF
• Airway assessment –
I. to see for cervical scoliosis
II. high arched palate(Marfan’s)
III. neurofibroma.
o Neurological assessment- pt with pre existing neurological deficit
areat↑risk of spinalcord injury during surgery .
o Also documentation of pre op neurological statusis imp.

35. EXERCISE TOLERANCE
 Maximal Oxygen Consumption (Vo₂ Max) : Most useful
predictor of post thoracotomy outcome
 Vo2 max= 15 (HRmax/HRrest)
-Vo₂ Max > 15ml/kg/min – tolerate pneumonectomy
-Vo₂ Max 10-15ml/kg/min - High risk and requires
careful evaluation
-Vo₂ Max < 10ml/kg/min- inoperable
 Traditional : Stair Climbing
5 Flights = Vo₂ Max > 20ml/kg/min
(1-flight== 20 steps– 1 step 6 inchs)
 SHUTTLE WALK TEST- b/w 2 points 10mts apart (inc. speed
every minute)
 6 MINUTE WALK TEST
-walk on level ground at max pace
-< 2000 ft = Vo₂ Max < 15ml/kg/min

36. INVESTIGATIONS
•Haemogram
•O2 carrying capacity
•Guide to transfusion
•RFT,LFT,Coagulation studies
•Chest radiograph(cxr)
•Ecg(document caridac ischemia and axis deviation)
•2D echo(cardiac function and rule out sturctural abnormality)
•ABG :Hypoxemia
•V/Q abn.> alveolarhypoventilation

38. •Pulmonary function tests
•Spirometry(extent of restrictive lung disease)
•FVC
•FEV1/FVC
•PEFR
•Peakinspiratory pressure
•Peakexpiratory pressure
•Vital capacity< 40% normal
•Req of postoperative ventilation
•CC > FRC
•Decreased DLCO

39. ANAESTHETIC TECHNIQUE
• PriortoOT psychologicalpreparationisamust
 -parentcounselling
 -counsellingreagardinwakeuptest
 -Preoperativesedation
• Depends on whether wakeup test is to be used
• NGTas postop ileus is common
• Induction :thiopentone/ propofol
• Maintainence:
-o2+N2O+lowiso+fent+vec
-high dose fentanyl+ TIVA with propofol infusion+ very low/no
isoflurane
• ScH:avoidinmuscle disorders
• P/O painrelief:spinal,epidural,caudal

42. Monitoring &lines
• Twowidebore iv lines
• Standard monitoring :
• ECG,NIBP,SpO2, vapour pressure, EtCO2,Airwaypressures
• Invasiveblood pressure,
• CVP monitoring/ pulm artery catheter if PAH
• Urine output,temperature
• Warm fluids,warmblanket
• Eyecare,pressure points &positioning
• Esophagealstethoscope
•OESOPHAGEAL DOPPLER-CO monitoring
as 20-30% dec in co in prone position
Compression stockings and pneumatic boots and avopid
anticoagulants for DVT prophylaxis

43. INTRAOPERATIVE CONCERNS
• Long duration of surgery
• Difficult airway
• Prone position complications
 Blood loss &replacement
• Hypothermia
• Lung isolation
• Spinalcord monitoring (Wake up test &evoked potentials)
• Venous air embolism
 Risk of malignant hyperthermia

44. PRONE POSITION &CONCERNS

45.  Foam bolsters are commonly used,
o one at the level of the chest below the axillae
o the other at the level of the anterior superior iliac spines.
 The arms should be abducted to no more than 90deg with
slight internal rotation and lie in front of the plane of the
body to reducethe risk of brachial plexus injury
 the ulnar nerve at the elbow which is at risk of pressure-
related injury when the arms are flexed in the prone
position
 If the arms remain by the patient’s side, then the thumbs
should be positioned pointing down to avoid over
pronation
 Avoid pressure on the abdomen

46. Prone position &concerns
 Arms are abducted less than90 degrees whenever
possible(prone “superman”position)
 Pressure points are padded
 Soft headpillow has cut outs for eyes and nose and a slot to
permit endotracheal tube exit
 Chest and abdomen are supported awayfrom the bed
◦ minimize abdominal pressure and preserve pulmonary
compliance
 Eyes checked frequently
 Elastic stockings and activecompression devices> lower
extremities >minimize pooling of the blood

47. Montral mattress
Jackson table
Wilson frame
Andrews table
The radius of curvature of
the Wilson frame can be altered by
means of a winding mechanism.
This allows a reduction in the
lumbar lordosis thus improving
posterior surgical access

49. Head positioning

50. Prone position
 Horseshoe shaped
adapter
 Superior access to airway &
visualization of eyes
the Mayfield head fixator- The head is held
in a clamp by pins which are inserted into
the outer table of the skull.

51. COMPLICATIONS
the incidence of ischaemic optic neuropathy may be increased compared with other prone-
positioning devices.

52. BLOOD LOSS &REPLACEMENT
• Usually associated with largeblood losses
– 15 to 20 ml/kg
– Typical blood loss for these procedures may exceed 50% of
patient’sblood volume and is directly related to
• Factors
– surgicaltechnique
– operativetime
– numberofvertebrallevels fused
– Whether bone graft is taken from the hip
– increased intra-abdominal pressure
– intermittent positive-pressure ventilation
– Anaesthetics
– meanarterialblood pressureor venous pressure
– plateletabnormalities
– dilutionalcoagulopathy
– primary fibrinolysis

53. Blood conservation
 Preop optimization of Hb
 hypotensive anaesthesia
 Coagulation control
 Cell salvage
 Antifibrinolytic agents
 Autologus blood transfusion
 Isovolemic hemodilution
 Reduce intrabd pressure
-NMBD
-Carefull positioning
-deep plane

54. BLOOD LOSS
• Techniques to reduce loss
– Avoid light anaesthesia,hypertension, hyperdynamic circulation,
hypercapnia
– Surgical hemostasis &vasoconstrictor use
– Proper positioning – avoid raised intraabdominal pressure
– Deliberate controlled hypotensive anaesthesia
– Pharmacological agents

55. Preoperative autologous blood
donation
 Hb> 11g%, HCT> 33%
 Not Preferred in smaller children and those with
neuromuscular dis.
 Donate 10-15% of blood volume
 Collected every 4-7 days starting 2 weeks prior
 Last donation no less than72 hours before surgery
 Started 1 month before
 Oral Fe/Erythropoietin supplementation(400U/kg 4 weeks prior)

56. ACUTE NORMOVOLEMIC HEMODILUTION
Removal of whole blood shortly before anticipated
significantblood loss
If Hb>10gm%(target- Hb-7gm%)
Collected in standard blood bags with anticoagulation
Simultaneous infusion of crystalloid(3:1) or colloid(1:1)
Stored atroom temperature
Re infused during surgery after major blood loss has
occurred
Re infused in reverse order of collection

57.  “an infusion of 5% albumin to maintain
CVP(range in study 5-23 mm Hg)
PAWP(range in study 7-27mm Hg).”
 “adequate oxygen delivery there is an absence of lactic
acidosis, MAP is 60 mmHg or more, the CI is 2.2
L/min/m 2 or more, and the mixed venous oxygen
saturation is 60% or more.”
 “hemodilution was done by removing venous blood
and replacing it with an infusion of crystalloid at a
ratio of 3 mL of crystalloid to 1 mL of blood with a
desired post-hemodilution hematocrit value of
30%.The venous blood is then returned to the patient
at the end of the surgical procedure.”

58. Blood salvage
Blood lost during surgery is collected using
commercially availableequipment and is then
anticoagulated,filtered for clots and debris, centrifuged,
resuspended in saline and reinfused to the patient.
Clotting factors need to be replaced using fresh
frozen plasma.
The technique is unsuitable in the presence of
malignancy or infection.

59. DELIBERATECONTROLLEDHYPOTENSIVE ANAESTHESIA
• Younghealthypatient- meanarterialpressure of50 to 60 mm
Hg(but maintain spinal cord perfusion)
• Adult patientwithcardiovasculardisease:higher
pressures
• scoliosis procedures involve mainly venous
bleeding(valveless epidural veins)
• Pre requisites:invasiveBP &urine output,ABG
• MAP of 50-60mmHg can be achieved with remifenatnil inf
and inhal agent alone without use of vasodilators

60. TECHNIQUES:
 highdose inhalational agent
 vasodilators: Nanitroprusside, nitroglycerine
-SNP dec. peripheral vascular resistance and BP while
inc. CO and tissue perfusion in the presence of
normovolemia or hypervolemia
- A reflex tachycardia may also occur
 B adrenergicblockers: esmolol,labetalol
-controlheartrateanddecreasecardiacoutput,reducing
bloodloss
 ᾳ2 agonist:dexmedetomidine
 *concern- ↓SC blood flow ↑ chanceof SCinjury
 during induced hypotension , overadministration of fluid
and blood to replace surgical losses should be avoided
until after instrumentation is complete.

61. Pharmacological agents
 APROTININ
 Bovine derived polypeptide(anaphylaxis)
 Test dose before prone and not used in next 6months
 Reduces blood loss in spine surgeries
 Inhibits plasmin &kallikrein and preserves platelet function.
 1-2 million KIU bolus - 0.25-0.5 million KIU/hr
 Or start @ 4mg/kg LD f/b infusion of 1mg/kg MD
 DESMOPRESSIN
 TRANEXAMICACID10mg/kg infusion @ 1mg/kg/hr

62.  Three main arteries traverse the length of the cord,
including
-1 anterior spinal artery
-2 posterior spinal arteries.
 Each arises from the vertebral arteries.
 Spinal arteries in the cervical and upper thoracic cord are
also supplied by radicular branches of vertebral ascending
cervical and superior intercostals arteries,
 Spinal arteries found in the thoracolumbar cord are
supplied by the artery of Adamkiewicz
 arteries of the mid thoracic cord are supplied by
intercostals radicular arteries
 cauda equina are supplied by the lower lumbar,
iliolumbar, and lateral sacral radicular arteries.

63. SPINALCORD MONITORING
 Postoperative neurologic deficitis one of the most feared
complications
 Increased risk in non idiopathic scoliosis
 Severe rigid deformity> 120°
 Congenital scoliosis
◦ Lipomas, tethered cord, cysts,teratomas
CAUSES OFNEUROLOGICAL INJURY
 Direct injurydueto instruments
 Spinalcord distraction
 Hypotension
 Ischemic(loss ofblood supply)

65. SPINALCORD MONITORING
 WAKE UPTEST
◦ Oldest and Gold standard
 SOMATOSENSORY EVOKEDPOTENTIALS(SSEPS)
◦ Allowscontinuousassessmentofdorsal/ascendingcolumns
 MOTOR EVOKEDPOTENTIALS(MEPS)
Monitorstheischemiasensitive ventralgraymatterofthe
descending/anteriorcolumns
 ELECTROMYOGRAMS
◦ Integrityofanteriormotor spinal cord

66. WAKE UPTEST
 By spine surgeon Pierre Stagnara in 1973
 Anaesthetist -Mme Vauzelle
 Explainingprocedureprior to surgery
 Repeat/enactbefore induction
 Stop propofol and MR(30-45mins before)
 Switchoffinhalation(20minsprior)
 Maintainon opioid
 Noreversalneedeif3twitchesarepresentonTOF
PROCEDURE
 Firstaskedto griphand,bysqueezinganaesthetistshands.
 thenmove legandfeet(bothmovingmeansscrewsarePlacedcorrectly)
 Preparationto restrainanyunwanted movement(1-2assistantsneeded)
 Ifptmoveshandsbutnotfeet–reducetheamountofdistractionandrepeattest(screwsneed
realignment)
 Onceptmovesfeet–deepentheplane

67.  Hazards & disadvantages
o assessment of voluntary motor function only provides a
brief assessment of the patient’s condition
o may fail to detect the onset of injury, ischemia, or
nerve injury.
◦ Results influencedby anaesthetics and the cognitive integrity
of the patient
◦ inadvertent extubation of the patientduring movement
in the prone position
◦ air embolism during adeepinspiration
◦ dislodgment of the instrumentation during violent
movements
◦ Injury

68. SSEP
 Mostwidely usedmodality
 assessonlytheintegrity oftheascending sensory tractsof thedorsal
column.
◦ Allowscontinuousassessmentofdorsal /ascending columns
 Monitoring SSEPs does not provide information about the
spinal motor pathways th at can be damaged during
corrective surgery
 Stimulation of peripheral nerve
◦ Posterior tibial /mediannerve
 The SSEPwaveforms are measured in amplitude and latency.
 Amplitude signifies the evoked potential wave ’s peak -to- peak
voltage difference.
 Latency represents the time from stimulus to peak of
response.p or cervical/thoracic epidural electrodes

69. PN
Dorsal column of
spinal cord
Ascends the dorsal
column
Medulla
Crossess the midline
Contralateral thalamus
Primary somatosensory
cortex

71. The electrical activity is recorded via scalp electrodes
Increased latency>10-15% significant
decreased amplitude >50 % significant
Muscle activity disturbance eliminated by NMB
Affected by hypotension, hypothermia,hypocarbia,
hypoxemia, anemia,andanesthetics

72. TypicalSSEP

73. MEP
Assess the integrity of the descending spinal motor
pathways (anterior and lateral corticospinal tracts
columns )
Electric or magnetic trans-cranial stimulation
Epidural ,neurogenic or myogenic MEP
Conduction of these stimuli through the motor
pathways is monitored as peripheral nerve impulses,
electromyographic signals, or actual limb movements.
1996,lang et al- transient loss of amplitude (no neuro
deficit
Complete loss of tce-MEP)
More sensitive to anesthetic interface

75. ELECTROMYOGRAPHY
 Intraoperative EMG monitors motor cranial nerves,
spinal or peripheral nerves at risk by looking at either
the spontaneous or evoked CMAPs of the corresponding
effector muscles
 normal - low frequency and amplitude
 When the nerve is stretched or irritated, high-frequency
neurotonic discharges will be produced, which alerts the
surgical team of potential motor nerve damage
 The absence of such discharges (i.e. a ‘‘negative
response’’) suggests either an intact nerve or total
denervation disrupting all nerve conduction.

78. Anaesthetic agents& EP
 Opioid haveleast effecton SSEPs
 Cortical SSEP is very sensitive to Potent inhalational agents ,
nitrous oxide.
 Sub cortical SSEP is more resistant
 MEPs is affected by
◦ nitrous+inhalational
◦ BZD, thiopentone
 MR haveno effecton SSEPs or MEPs

80. HYPOTHERMIA(lessthan36deg)
 Long duration of surgery
 Transfusion of blood &blood products
 Hazards
◦ Impaired coagulationd/t Dec plateletfunction
◦ Wound infection(impairedimmune functanddec cutaneousbldflow)
◦ Delayed recovery(dec drug metabolism)
◦ Acid/base changes
◦ hypothermia reduces conduction velocity in peripheral
nerves and increases synaptic delay in awake and
anesthetized patients.
 SSEP latency increases linearly with decreasing temperatures,
whereas the amplitude of the cortical SSEP is unchanged with
moderate hypothermia.
 Prevention
◦ Monitoring ,warm fluids,warming blankets,warm irrigation solutions

82. EXTUBATION
 Extubation parameters
VC > 10ml/kg
TV > 5ml/kg
Spont resp rate < 30/min
Negative inspiratory force > 30cm H2o

83. Predictors ofpost op ventilation
 Patient factors
◦ Severe restrictive lung disease
 Vital capacity< 35%
 Pimax > -40cm H2O
 PEMAX > + 40cm H2O
 PaO2 < 60 mmHg
 PaCO2 > 50 mm Hg
◦ Right ventricular failure
◦ Pre existing neuromuscular disease
◦ Congenital heart disease
◦ Obesity

84. Surgical factors Blood loss > 30 ml/kg
Surgical invasion to thoracic cavity
Surgical factors
◦ Blood loss > 30ml/kg
◦ Surgical invasion to thoracic cavity

85. Postoperative concerns
Paralysis
 Pulmonary complications
(Pneumothorax/hydrothorax/atelectasis)
Pain management
Pulmonary function
Post op ventilation
Hyponatraemia
Bleeding & coagulation abnormalities

86. PAINMANAGEMENT(multimodal analgesia)
 For frequent physiotherapy and early mobilization and thus reduce
post op resp complications.
 Parental opioid (48 hours)
◦ continuous infusion/iv PCA
 NSAIDs
◦ Opioid sparing effect
◦ Reports that ketorolac inhibits spinal fusion
 Epidural infusion(paravertebral catheter)- anterior correction
◦ Local anaesthetic + opioid infusion
 Intrathecal opioid
◦ Morphine 5 – 10µg/kg

87. OPTIMISATION OFPULMONARY
STATUS
 Incentive spirometry
 -Coughing and deep breathing should be
encouraged
 -Bronchodilators therapy ifreactive airway disease also present
 -Adequate analgesia
 Others-
Maintain urineoutput >0.5ml/kg/hr
Compression stockings/ pneumatic legpumpsforDVTprophylaxis

88. summary
• In Kyphoscoliosis there is involvement of various
organ systems.
• Anaesthesia is often needed for corrective
orthopaedic surgery.
• A detailed preanaesthetic assessment and optimization
of the respiratory and cardiovascular systems is
important.
• Intraoperative considerations are monitoring,
temperature and fluid balance maintenance, positioning,
spinal cord integrity monitoring and blood conservation.
• Post operative concerns- intensive care, respiratory
care and pain therapy