Elective spine surgeries

By: Siti Mohaini Anora bt Ismail
Moderator: Dr. Laila Mukmin

 Anaesthesia for major spinal surgery, such as
spinal stabilization following trauma or
neoplastic disease, or for correction of scoliosis,
presents a number of challenges
 Commonly have preop. co-morbid conditions eg
serious CVS & resp. impairment
 Airway management may be difficult

Mainly present with one of 5 pathologies:
 Trauma (eg unstable vertebral fracture)
 Infection (vertebral abscess)
 Malignancy (metastatic/primary dz with spinal
instability, pain & neurological compromise)
 Congenital/idiopathic (example scoliosis) or
 Degenerative disease

 Neurological dysfunction (compression)
 Structural instability (abnormal displacement)
 Pathologic lesions (tumor / infection)
 Deformity (abnormal alignment)
 Pain (spinal column/discogenic/facetogenic)

 Patient‟smedical condition
 Surgical procedures – duration & surgical
approach

Airway Evaluation
 Mallampati Classification & various radiological
predictors of difficult intubation & range of motion
of the neckpain or other neurological
symptoms during manipulation

Pulmonary Evaluation
 patient at risk of pulmonary dysfunction
 corrective surgeries (scoliosis)
 old age (degenerative spine diseases)
 acute fracture of cervical spine
 require special anaesthetic technique like one
lung ventilation

Cardiac Evaluation
 Cardiac function m/be compromised by
underlying medical conditions, neuromuscular
disorder , rheumatoid arthritis , high cervical cord
injury

Neurologic Evaluation
 Careful documentation of preexisting neurological
deficit is essential
 Extent of neurological dysfunction may dictate
intubation technique & choice of anesthetic
agents

Haematological evaluation
 Many pts with spine pathology will have been
taking some NSAIDs for analgesia
 Proper coagulation profile has to be ordered
 1 author suggest to stop NSAIDs at least 10
days before elective surgeries (Samantaray
2006)

Premedication
 Depends on haemodynamic stability and
neurological status of patient

Minimum Ix Optional Ix

Airway •Cervical spine lateral x-rays with •CT scan
flexion/extension views (for pts with
rheumatoid arthritis)
•Plain CXR
Resp. system •Arterial blood gas analysis •Pulmonary function tests
•Pulmonary diffusion capacity (bronchodilator
•Spirometry (FEV1, FVC) •reversibility)
•Pulmonary diffusion
capacity
CVS •ECG •Dobutamine-stress
•Echocardiography echocardiograph
•Dypiridamole/thallium
scintigraphy
Blood tests •Full blood count •LFT
•Clotting profile
•Blood cross match
•Urea, electrolytes
•Albumin, calcium (neoplastic
disease)

 Standard monitoring :
 ECG
 NIBP
 Pulse oximetry
 Capnograph
 Temperature

 Special monitoring
 for long procedure with potential for large volume shift,
risk of venous air embolism & pts who have
complicated medical hx, haemodynamic instability
(spinal shock) or in procedures where special
anesthetic techniques are planned like deliberate
hypotension, endoscopic surgeries
 Invasive BP, CVP, urine output

 Swan Ganz cathetersevere cardiac or resp dz

 Specific monitoring
 Neurologic monitoring procedures that may
compromise the integrity of the spinal cord (SC): direct
SC/ nerve damage during instrumentation, distraction
injury or reduced SC perfusion resulting in ischemia
 Spinal fusion, removal of SC tumors & vascular lesion
are at more risk
 Somatosensory Evoked Potential (SSEP)
 Motor Evoked Potential (MEP)
 Wake up test ~ adjunct (reliable)
 Electromyographic monitoring (EMG)

MEP
SSEP

Dorsal /
Posterior

SSEP

MEP

Ventral /
Anterior

 To detect neurological injury and prevent devastating,
irreversible damage
 For most, loss of motor worse than loss of sensory

 Spinal
instrumentation
 Scoliosis correction
 Spinal cord
operations
 Aortic surgery

 Stimulate a peripheral nerve often post tibial
nerve
 Detect a response with epidural or scalp
electrodes
 The evoked potentials are averaged more than 2
to 3 mins to eliminate background noise then
displayed as voltage against time
 Nerve injury m/be indicated by decreased
amplitude or increased latency

 Transcranial electrical impulses stimulate the motor
cortex
 Resulting signal detected with epidural electrodes
or as compound muscle action potentials (CMAPs)
 Complement with MEP when risk of spinal artery
injury – anterior approach – ascending tract will be
intact

 Provides snapshot of SC motor function
 Surgery is stopped
 Volatile/anesthetic agent switched off &
emergence allowed
 Pt is asked to move their feet
 If can move, anaesthesia recommenced
 Assistance is needed to prevent pt movement
which may cause accidental extubation or loss of
vascular cannulae
 In the event of new paraplegia, all implants should
be removed, hypotension & anaemia corrected & a
course of high dose methylprednisolone
commenced

 Incidenceof motor deficit or paraplegia after
surgery to correct scoliosis:
 Absence of SC monitoring : 3.7 – 6.9%
 With intraop. monitoring : 0.5%
 American Academy of Neurology: “considerable
evidence favours the use of monitoring as a safe &
efficacious tool in clinical situations where there is a
significant nervous syst risk, provided its limitations are
appreciated”
 It is now considered mandatory to monitor SC function
for these types of procedures
 Raw et al, BJA 2003; 91: 886-904

 Major prob: maintenance of basic CVS monitoring
techniques during positioning of pt
 Represent a stress to circulatory integrity & it is very
difficult to prevent an almost total monitoring
“blackout” as anesthetized pts are turned from the
supine to prone position (most frequently used
position)
 Particular attention on neck, arms, eyes to protect
pressure-sensitive areas

 Regardless of how well positioned at start of
procedure, on-going vigilance with regard to
position is essential because pt situation may
change after movement during wakeup test or
manipulation of the operating table

Prone Positioner C-Shaped Face Piece

Horseshoe Head Rest Mayfield Tongs

 Restriction of  Obstruction of Inf
diaphragm Vena Cava
 by abdominal contents  Decreases preload
 and weight of pt against  Increases perivertebral
thorax venous pressure
 Create restrictive
 (pronemay improve
defect
oxygenation when
 Increased peak
abdomen hangs free-
inspiratory pressure
(barotrauma) chest roll or frame)

Complication Strategy

ETT •Reinforced tube
obstruction/malposition

Direct pressure injury •Mayfield head frame
•Ensure eyes, chin, nose are free from contact with any surface;
check vigilantly
•Pad all pressure points
•Place breasts neutrally or medially
•Keep male genitalia free of compression from bolsters or thighs

Increased •Allow for chest excursion and free abdominal movement by using
thoracic/abdominal chest & thigh rolls and/or special mattress for OR table
pressure

Peripheral nerve injury •Avoid positions known to cause pain or paresthesia when pt is
awake
•Pad axillary and ulnar neurovascular bundles
•Arms at sides when turning supine to prone
•Consider use of SSEP and MEP to monitor for brachial plexus
ischemia
•Shoulder abduction < 90° and elbows placed in flexion

Complication Strategy

Swelling/dependent •Judicious use of crystalloids for fluid replacement
edema of the tongue and •Check for ETT cuff leak prior to extubation
oropharynx

Vascular occlusion •Avoid extremes of cervical range of motion
•Watch for signs of jugular venous outflow
obstruction

 Frame based table
 Allows abdomen and
chest to hang freely
 May allow 180
degree rotation

 Maintains flexed
position for spinal
surgery
 Intrabdominal
pressure may be
increased if
supporting pads are
not properly placed

 Brachial plexus may be
stretched
 Ulnar nerve not properly
padded
 Eye damage from pressure
 Nose pressure
 Excessive compression to
inferior vena cava
(minimized by padding
under inf iliac spine & chest
rolls)

 Aim: to maintain a stable anaesthetic depth allowing
for intraoperative neurophysiological monitoring
 Can be achieved with various techniques
 Anaesthetic technique impacts upon SC monitoring
 Volatile agents, propofol & nitrous oxide all depress
SSEP and MEP
 Opioids have little effect
 NMB agents may reduce background noise when
using SSEP but a profound block will prevent CMAP
(Compound ms action potentials)
 Decrease in BP & Temp may also depress signals

 Any standard technique is acceptable
 Consider wire reinforced tube to avoid kinking
and occlusion for prone, allows maximal
banding to remove it from surgical field and
prevent compression from retractor during
cervical surgical procedures

 Cervical spine surgery require special
consideration for airway management
 High incidence of difficult airway
 20% grade 3-4 glottic visualization
 Rheumatoid dz: 48% difficult intubation
 Cervical fracture: 23%
 Cervical tumor: 24%
 Other predictor of difficult intubation include:
 Upper vs lower C-spine dz
 Presence of external or internal fixation devices

 Risk of neurologic injury is more when
endotracheal intubation is attempted in patients
suffering from C-spine dz
 Various studies have been made for evaluating
optimal techniques for intubating patients at risk
for cervical spine injury
 No single technique has been proved to be
superior than the other
 Aware that there is risk of SC injury with
laryngoscopy
 Recognize the increased probability of
encountering a difficult a/way
 Attention to minimizing motion of the C-spine

 The adult cervical spine below C2 is unstable or
on the brink of instability when one of the
following conditions are met:
 (i) all the anterior or all the posterior elements are
destroyed;
 (ii) there is >3.5 mm horizontal displacement of one
vertebra in relation to an adjacent one on a lateral x-
ray; or
 (iii) there is more than 11° of rotation of one vertebra
to an adjacent one
 Above level C2, eg of unstable injuries include:
 disruption of the transverse lig. of atlas (distance >3
mm in adults betw. post. corpus ant. arch of C1 &
ant. border of odontoid process
 Jefferson burst fracture of the atlas following axial
loading (causes atlantoaxial instability

 StandardN2O-opioid-based technique with
NMB agent and low dose inhalational agent
supplementation (Samantaray)
 Maintenance dose of anesthetics is altered –
may have altered pharmacokinetics due to:
 Muscle wasting
 Decreased serum albumin
 Eg. Suxamethonium contraindicated in muscular
dystrophy – risk of rhabdomyolysis, hyperK,
cardiac arrest

 Pt
at high risk for neurologic injury intraop m/be
managed with either
 Induced hypertension
 Maintenance of systemic BP within 10-20% of preop
values
 Some centers utilize neurologic monitoring during
placements of patients in the operative position to
prevent position related injury
 Type, duration and extent of surgery may guide
the approach to fluid administration & replacement
 Avoid dextrose containing solution risk of worsening
neurosurgical outcome in the presence of
hyperglycemia during SC ischemia

 Surgical procedures involving significant bone
work at multiple levels may be a/w large intraop
bld loss & higher requirement for transfusion of
bld and bld products
 Strategies to reduce @ remove risk of allogeneic
transfusion:
 Preop autologous donation
 Acute normovolemic hemodilution
 Perioperative cell salvage techniques
 Deliberate hypotension
 Pharmacologic interventions; tranexamic acid

 Complexity & extent of surgery, operative time, pt‟s co-existing dzs
 Bld loss/ transfusions
 Complications that occurred during or immediately after surgery
 Some may need post-op care in ICU
 Adequacy of a/way after ETT removal
 Leave ETT in place until fully awake, respond to command & able to
manage own a/way
 Some leave ETT in place and spray lidocaine down trachea to prevent
or minimize coughing or bucking on ETT for about 15-30 mins
 Consider inserting an a/way exchange catheter through ETT before
removal in case need of immediate reinsertion of ETT if a/way
obstruction from early/delayed swelling, bleeding or haematoma
 Cuff-leak test, if any uncertainty to perform flexible fibreoptic
 Spirometer on modern anesthesia machines can also be used to
quantify leakage; expired-inspired vol

Defer extubation Consider extubation
Inability to open eyes & not obeying Awake & obey command
commands
Agitated or combative Regular spontaneous breathing
Poor resp. efforts
O2 sat <94% O2 sat >94%
Hypercarbic (PaCO2 >50) Normocapnic (30<PaCO2<50mmHg)
Hemodynamic unstable Hemodynamic stable
Hypothermic (<36°) Normothermic
Neuromuscular blockade completely
reversed (TOF>90%, sustained head lift &
strong hand grip)
Operating time >10 hrs Operating time <10hrs
Blood transfusion >4 units Blood transfusion <4 units
Evidence of facial edema & macroglossia
-ve cuff-leak test +ve cuff-leak test
Evidence of pharyngeal & laryngeal edema No evidence of pharyngeal & laryngeal
on flexible fibreoptic bronchoscopy edema on flexible bronchoscopy

Table 50.1 Criteria for extubation following complex spine surgery in prone position,
Case Studies in Neuroanesthesia and Neurocritical Care, George A. Mashour & Ehab Farag, page
162

 Individualized for each patient
 To consider preop status, surgical procedures,
intraop cx & pain tolerance
 Good post-op analgesia
 LA, opioid in epidural space before closing
 PCA
 Oral/ rectal analgesics

Early
 Fluid volume deficit
 Neurologic injury or deficit
 Dural tear with cerebral spinal fluid leakage
 Anemia
 Urinary retention
 Ileus
 Atelectasis/ pneumonia
 Venous thrombosis
 Specific to anterior cervical proedures: dysphagia,
hoarseness, a/way obstruction from oedema

Late
 Skin breakdown
 Wound infection
 Spinal instability (after wide lumbar
decompressive procedures not accompanied
by fusion)
 Hardware failure
 Pseudoarthrosis
 Epidural fibrosis
 Transitional syndrome
 Arachnoiditis

 Perioperative vision loss (72% of
perioperative vision loss reported are d/t
spine surgery in prone position)
 perioperative ischemic optic
neuropathy rare (3/10 000)
 Central retinal artery or vein occlusion
 Occipital lobe infarct
 Corneal abrasion most common eye
injury after spine surgery (rarely leads to
permanent vision problems)

Ischaemic Optic Central Retinal Artery
Neuropathy (ION) Occlusion (CRAO)
Etiology Intraop ↓ BP Direct external pressure
Prolonged surgery Emboli
↑ Blood loss
↑ Crystalloid infusion

Mechanism Ischaemia ↓ Ocular perfusion pressure
Orbital edema → stretch and
compression of ON

Clinical Painless Painless
Features Bilateral Unilateral
↓ Light perception Periorbital swelling or
↓ Visual fields echymosis

 Lat. curvature & rotation of the thoraco-
lumbar vertebrae with a resulting rib cage
deformity
 Idiopathic @ secondary to neuromuscular
dz, infection, tumor or injury
 Cobb Angle > 10° considered abnormal
 Surgery indicated when >40°
 Restrictive lung defect & dyspnoea on
Cobb Angle
exercise: > 65°
 Resp. failure, pulm. HPT, Rt heart failure:
>100°

 Lat. curvature & rotational deformity of the thoraco-
lumbar vertebrae with a resulting rib cage deformity
 occurs in up to 4% of the population
 Most cases idiopathic (70%) with male:female ratio of
1:4
 Idiopathic/secondary to neuromusc. dz, infection, tumor
or injury
 Cobb Angle > 10° considered abnormal
 Surgery: Cobb angle >50° in the thoracic, or >40° in the
lumbar spine
 Restrictive lung defect & dyspnoea on exercise: > 65°
 Resp. failure, pulm. HPT, Rt heart failure: >100°

Classification of scoliosis aetiology – taken from BJA CEACCP 2006;6:1;13-16
Idiopathic (70%) Early onset (infantile)
Late onset (juvenile)
Neuromuscular (15%) Crebral palsy
Myopathies
Poliomyelitis
Syringomyelia
Friedreich‟s ataxia
Congenital Vertebral anomalies
Rib anomalies
Spinal dyraphism
Traumatic Vertebral fractures
Radiation
Surgery
Syndromes Marfan‟s
Rheumatoid arthritis
Osteogenesis imperfecta
Mucopolysaccharide disorders
Neurofibromatosis
Neoplastic Primary tumours
Secondary tumours
Infection Tuberculosis
Osteomyelitis

 Surgery may slow the decline in resp. fx & improve
QOL by improving posture & helping nursing care
 Pts should be offered stabilization before the
cardio-resp. dysfx prevents surgery
 Surgery aim to correct curve & fuse the spine,
improving posture & halting the progression of
pulm. dysfx
 Approach: posterior, anterior or combined, recent –
thoracoscopy
 Left untreated, idiopathic scoliosis rapidly
progresses & is often fatal by the 4th/5th decade of
liferesult of pulm. HPT, right vent. failure, or
resp. failure

 Most commonly used
 Skin & supraspinous lig. are incised & paraspinal
ms reflected
 The vertebral laminae are then decorticated, facet
joints destroyed & spinous processes removed
 Bone graft is packed over the raw decorticated
surfaces & stainless steel rods are used to correct
the deformity & provide stability for bony fusion
(secured with pedicle screws or laminar hooks)

 Large thoraco-abdominal incision
 Exposure of vertebral bodies & removal of
intervertebral discs to allow for greater
movement
 One lung ventilation is rarely necessary to
improve surgical access, except in high
thoracic curves

 Combined ant & post in single operation
results in more rapid recovery & less time in
hospital

 Take note aetiology, location & degree of
scoliosis
 All pts require full hx, physical examination &
appropriate investigations focusing on CVS &
resp. system
Routine investigations Routine (blood tests ) Additional investigations

Plain CXR FBC ABG – if spirometry not
Pulm fx tests Coagulation screen possible
FEV1 and FVC Urea & electrolytes ECG & ECHO (non-
Ca & phosphate idiopathic scoliosis)
Blood cross-match

 Good exercise tolerance & absence of resp. sx
indicates acceptable cardio-resp. reserve
 Pts with more severe degrees of scoliosis > 100°,
right ventricular hypertrophy on ECG, or evidence
of right HF on examination require ECHO
 Scoliosis surgery can be well tolerated despite
severe restrictive lung dz (FVC <32%)
 Approx. 25% pts with idiopathic scoliosis have
mitral valve prolapse rarely of clinical
significance & antibiotic cover is given

 Preop assessment of pt with neuromuscular ds
or immobility is more difficult
 Unable to give a hx of exercise tolerance or
perform spirometry adequately
 Muscular dystrophies m/be complicated by
subclinical cardiomyopathy
 Duchenne muscular dystrophy: >50% have
some degree of dilated cardiomyopathy & EF
<45% by 15 yo
 Need ECHO to assess left ventricular fx
 Normal study does not exclude significant
pathology

 Use of invasive monitoring lines & catheters along
with postop analgesia plan should be explained
fully to pt & family
 Sedative premed. with oral midazolam (0.5mg/kg)
can be offered
 Pts with Duchenne muscular dystrophy m/be on
corticosteroid therapy – require perioperative
supplementation

 Aim to maintain stable anaesthetic depth allowing
intraop. neurophysiological monitoring
 Induction by IV propofol
 Non-depo NMB drug
 Tracheal intubation with an armoured tracheal tube
 Anaesthesia maintained by sevoflurane at 0.6 MAC
in air & oxygen
 Infusion of remifentanil
 Bolus of IV morphine toward the end of surgery
 Suxamethoniumcontraindicated in muscular
dystrophy dt risk of rhabdomyolysis, hyperkalemia,
cardiac arrest

 Bld loss & heat loss, potential for haemodynamic
instability
 Addition to standard paediatric GA monitoring :
 Invasive arterial pressure monitoring
 Urinary catheter
 2 large peripheral iv cannulae
 Central venous cannula if significant comorbidity or
inadequate iv access
 CVP may be misleading as a guide of ventricular
filling in prone position
 Cardiac ouput monitoring with oesophageal Doppler
 Temp monitoring + IV fluid warmers, warm air
blankets at induction and throughout procedure

 Monitor volume status & bld loss carefully in all
pts
 Regular Hb, platelet & coagulation estimations
 Children with neuromuscular dz are at increased
risk of excessive bld loss: they have more
osteopenic bone & it has been suggested that
the absence of dystrophin causes vascular
pathophysiological changes

 Careful positioning to avoid IVC compression
 Prevent hypothermia
 Correction of caogulopathy
 Good surgical technique
 Compression stockings, pneumatic boots as
thromboprophylaxis
 Avoid anticoagulants
 Controlled hypotension MAP 50-60 mmHg
remifentanil infusion & volatile agent w/out need for
vasodilators
 Hypotension & surgical manipulation may reduce SC
perfusion & so risk neurological injury
 Important to maintain continuous neurological
monitoring & adequate haematocrit to ensure oxygen
delivery

 Predonation of blood
 Intraoperative acute normovolaemic
haemodilution
 Intraoperative cell salvage

 SSEP ± MEP
 Intraoperative wake up test

 Good post-op analgesia essential to allow
frequent physiotherapy & early mobilization
 Reduce risk of resp. complications
 Multimodal approach
 Combined simple analgesics, systemic opioids &
regional anaesthesia
 Epidural catheter or paravertebral catheter during
an anterior correction can be placed intraop. by
the surgeon
 After initial neurological assessment, a loading
dose of LA is given followed by a continuous
infusion

 Additional analgesia is needed d/t the size of
the wound & the surgical disruption of the
epidural space
 Opioids can be administered intravenously,
intrathecally or via the epidural space
 Epidural infusion + CMI + regular Paracetamol
 ± NSAIDS

 Airway assessment & management
 Anticipate difficult a/way
 Limited mouth opening & limited neck movement
 Establish the range of symptom-free neck movement
 Elicit sn & sx of possible nerve impingement or SC
compression
 Pain on mastication – TMJ involvement
 Increasing hoarse voice – suggest arytenoid
cartilages involvement
 Atlantoaxial instability
 Radiograph of cervical flexion & extension for all pts
with neurologic sx & those taking regular steroids or
dz-modifying antirheumatic drugs

 Neutral position – to prevent damage to neurologic
structures
 This m/be different for each pt & care should be taken
to enlist the pt‟s cooperation in finding the most
comfortable neck position

 Extubation – gross assessment of neurologic fx had
been completed before extubating as worsening of fx
may precipitate need for urgent imaging or re-
operation
 During preop need to warn pt that they may awake
with a breathing tube in place & ask to perform simple
tasks on command
 Check for leak before extubation
 Head-up position & use of corticosteroids may
accelerate resolution of edema

 Autosomal dominant d/o
 Melanogenic abnormalities café-au-lait macules,
freckling, hyperpigmentation
 Tumor formation usually manifests in puberty
 May present for surgical procedures involving
peripheral nervous syst. tumors (neurofibromas),
CNS tumors(benign optic gliomas, astrocytomas),
scoliosis or other skeletal abnormalities
 Association with phaeochromocytoma
 Thorough & systematic approach to pt is essential

 Particular concern airway
 Difficulties presented by cervical spine
immobilization
 Neurofibromas may develop in the trachea &
resp. tree
 Tracheobronchial tumors m/be asymptomatic for
many years & may present with normal chest
radiographs
 Recent history of dyspnea, cough, dysphagia,
dysarthria, stridor or change in voice
 Awake fibreoptic intubation
 May use dexmedetomidine as sedation
preservation of resp. drive (+ fentanyl)

 Infection
 Preopassessment lung function & CXR
 Complete treatment
 Document neurologic deficit pre-op

 Aims to reduce ts trauma, prevent iatrogenic prob. &
preserve spinal segmental motion & stability
 The most compelling advantages of endoscopic
procedures over open surgery are:
 Smaller incisions & less ts trauma
 Minimal bld loss
 Earlier return to activities & work
 Easier operative approach in obese pts
 Local/regional anesthesia combined with conscious
sedation can be used
 In most cases, less postop. pain medication is required
 As a consequence, outpt procedures are possible

ENDOSCOPIC SPINE SURGERY

Indications: Contraindications:
 Clinically relevant instabilities
 Lumbar, thoracic & cervical  Central spinal canal stenosis
disc herniations with radicular
symptoms
Relative contraindications:
 Lateral spinal canal (recess) &
foraminal stenoses with  Large disc herniations with
radicular symptoms cauda equina synd. or a fresh
motor deficit
 Degenerative facet joint cysts
with radicular symptoms  With the exception of cases with
large interlaminar windows &
good
 Interlaminar endoscopic access,
adequate decompression may
not be possible

 Many surgeons prefer GA for the traditional
techniques, but LA with or w/out conscious
sedation is an option for most endoscopic
approaches
 However, one consideration should be that in a
pt in the prone position, a conversion from local
to GA would require complete abandoning of the
procedure, endotracheal intubation, repositioning
and renewed preparation of the operative field
 Especially with cervical procedures, unconscious
head& neck movement are difficult to control &
may incur additional risks

 Interlaminarapproach
 Posterolateral approach
 Far or Extreme lateral approach

 Anteriorapproach
 Posterior approach

 GA
 Adult & children >45kg double lumen tube
 Children <45kg may require selective
intubation of the ventilated lung
 Position checked by fibreoptic
 Pt position in lateral decubitus then check tube
position by auscultation & fibreoptic

Univent

Cohen Arndt

 Manoeuvres are directed at minimising atelectasis in
the ventilated lung & shunt in the non-ventilated lung
 Set initial VT at 10 ml/kg & adjust resp. rate to
maintain normocapnia
 Use FIO2 0.5 initially & increase to 1.0 if required
 Ensure proper tube position (auscultate,
bronchoscopy) & suction at regular intervals
 Apply continuous positive a/way pressure to the non-
ventilated lung to expand it just enough so as not to
interfere with the surgery, thus reduce shunt

 Application of PEEP to the ventilated lung may
reduce atelectasis but oxygenation may deteriorate
d/t increase in shunt through the other lung
 Oxygenation can be insufflated into the non-
ventilated lung via a suction catheter
 Alternatively, the non-ventilated lung can be
inflated briefly with 100% O2 at intervals

 Persistent hypoxia that does not respond to the
above manoeuvres must be treated with
resumption of two-lung ventilation with 100% O2
 Failing this, clamping of the pulmonary artery (of
the surgical lung) should improve oxygenation

 Spinal anaesthesia in adults, D. A. Raw et. al, BJA
2003; 91: 886-904
 Anesthesia for spine surgery, A. Samantaray,
Indian Anaesthetists„ Forum 2006
 Scoliosis surgery in children, M.A. Entwistle and D.
Patel, Continuing Education in Anaesthesia,
Critical Care & Pain, BJA , 2006; 6: 1: 13-16
 Anaesthesia for scoliosis surgery in children,
Euroanaesthesia, Glascow, Woloszczuk – Gebicka
2003

 Clinical Anaesthesiology by G. Edward Morgan
 Oxford handbook of anaesthesia by Keith G.
Allman
 Yao & Artusios‟s Anaesthesiology
 Intraabdominal pressure, blood loss and spinal
surgery, Anesthesia-Analgesia 2000;91:552–7
 Ames et al, Local anaesthesia for laminectomy
surgery, British Journal of Neurosurgery, 1999,
Vol. 13, No. 6 , Pages 598-600
 Case Studies in Neuroanesthesia and
Neurocritical Care by George A. Mashour and
Ehab Farag

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