Anesthesia for Patients with Spinal Cord Injury

Dr. AshishModerator : Dr.R.Tope

www.anaesthesia.co.in anaesthesia.co.in@gmail.com

Blood supply

Two posterior spinal arteries Anterior spinal artery – formed by the confluence of

two vertebral arteries

The lower cervical cord is a region of relative ischemia and is vulnerable for ischemic injury should the anterior spinal artery be compromised between the foramen magnum and C8, the cervical watershed.

Spinal Cord Paralysis Levels

C1-C3 All daily functions must be totally assisted Breathing is dependant on a ventilator Motorised wheelchair controlled by sip and puff or

chin movements is requiredC4 Same as C1-C3 except breathing can be done

without a ventilatorC5 Good head, neck, shoulder movements, as well as

elbow flexion Electric wheelchair, or manual for short distances

C6 Wrist extension movements are good Assistance needed for dressing, and transitions from

bed to chair and car may also need assistanceC7-C8 All hand movements Ability to dress, eat, drive, do transfers, and do upper

body washes T1-T4 (paraplegia) Normal communication skills Help may only be needed for heavy household work

or loading wheelchair into car

T5-T9 Manual wheelchair for everyday living Independent for personal careT10-L1 Partial paralysis of lower bodyL2-S5 Some knee, hip and foot movements with possible

slow difficult walking with assistance or aids Only heavy home maintenance and hard cleaning will

need assistance

Treatment of Spinal Injuries

No Current Effective Treatment

Prevention is Key– all current medical and surgical treatments aimed

to prevent further injury to the spinal cord.

Spinal Cord Injuries

May occur with neck or back trauma Associated with blunt head trauma,

especially when casualty is unconscious Can occur with penetrating trauma of

vertebral column Improper handling may cause further injury

Mechanisms of Spinal Injury

Hyperextension Hyperflexion Compression Rotation Lateral Stress Distraction

Pathophysiology

Damage – Begins centrally in grey matter and spreads centrifugally.

Primary insult –B/W Time of injury and initial careSecondary insult – Delayed swelling Continued mechanical trauma Low perfusion Endogenous factors Initial segmental loss can be withstood because

only small portion of grey matter neuronal pool is involved.

– ASIA A: Complete: no motor or sensory function is preserved in the sacral segments S4-S5

– ASIA B: Incomplete: sensory but NOT motor function is preserved below the neurological level and includes the sacral segments

– ASIA C: Incomplete: motor function is preserved below the neurological level and more than half of key muscles below the neurological level have a muscle grade <3

– ASIA D: Incomplete: motor function is preserved w/ muscle grade > 3

– ASIA E: Normal

Diagnosis and management of acute spinal cord injury

Initial assessment and immobilization Resuscitation and medical management Radiological diagnostics Anaesthesia management Surgical therapy Post op critical care management

Initial assessment and immobilization

*HistoryPain/paresthesiasTransient or persistent motor or sensory symptoms

*Physical ExaminationAbrasions/hematomaTendernessInterspinous process widening

Immobilize the casualty’s head and neck manually

Apply a cervical collar, if available, or improvise one

Secure patient to short spine board if extracting from a vehicle

Secure head and neck to spine board for extraction

Transfer patient to long spine board as soon as feasible

Logroll in unison Stabilize head and neck

with sandbags or rolled blankets

Secure casualty to long spine board with straps across forehead, chest, hips, thighs, and lower legs

Resuscitation and medical management ATLS principles

Airway Breathing Circulatory Neurologic Classification Spinal Imaging GastroIntestinal System Genitourinary System Skin

Airway

Risk Associated with Level of InjuryDecision to IntubateAirway Intervention

Risk Associated with Level of Injury cont’d

Ventilatory Function– C1 - C7 = accessory muscles– C3 - C5 = diaphragm

“C3-4-5 keeps the diaphragm alive!– T1 - T11 = intercostals– T6 - L1 = abdominals

Decision to Intubate:

Need for Artificial Airway is Usually Related to Resp Compromise e.g.

– Loss of innervation of the diaphragm (C 3-4-5 keep the diaphragm alive)– Fatigue of innervated resp muscles – Hypoventilation – SaO2 <60, PaCO2 >45– V/Q mismatch – PaO2/FiO2 <250– Secretion retention– Atelectasis

Decision to Intubate Related to Neurological Level

Occiput - C3 Injuries (ASIA A & B)– Require immediate intubation

and ventilation due to loss of innervation of diaphragm

Decision to Intubate Related to Neurological Levelcont’d

C4-C6 Injuries (ASIA A & B)– Serious consideration for prophylactic

intubation and ventilation if: Ascending injury (requires serial M/S

assessment by a trained clinician)Fatigue of unassisted diaphragmInability to clear secretions

Airway Intervention

Maintaining Spinal Precautions– Supine position

Maintain neutral C-spine– Remove rigid collar and sandbags– Manually stabilize C-spine2 person technique:

– 1st person to provide manual in-line stabilization (not traction) of C-spine

– 2nd person intubates

Complications of cervical spine immobilization

Airway:delayed tracheostomy-poor oral hygeine Breathing: prolonged mechanical ventillation-VAP Circulation:difficult central line insertion and access,

increased thromboembolism Neurological: increased ICP Gut: gastrostasis,reflux and aspiration;delayed

enteral nutrition Skin: pressure sores around collar Staffing: minimum 4 for log rolling; cross infection

Breathing

Cough Function C1-C3 = absent C4 = non-functional C5-T1 = non-functional T2-T4 = weak T5-T10 = poor T11 & below = normal

Breathing cont’d

Vital Capacity (acute phase) C1-C3 = 0 - 5% of normal C4 = 10-15% of normal C5-T1 = 30-40% of normal T2-T4 = 40-50% of normal T5-T10 = 75-100% of normal T11 and below = normal

Breathing cont’d

SCI Respiratory Sequale– Atelectasis– Ventilatory failure

(PaCO2 > 50mmHg and pH < 7.30)

– Increased secretions– Pneumonia– Pulmonary emboli– Pulmonary edema (Autonomic)

Breathing cont’d

Intervention

– O2 therapy

– Assisted ventilation – Medications (bronchodilators)

Circulatory

Spinal Shock

Temporary suppression of all reflex activity below the level of injury

Occurs immediately after injury

Intensity & duration vary with the level & degree of injury

Neurogenic Shock

The body’s response to the sudden loss of sympathetic control

Distributive shock

Occurs in people who have SCI above T6 (> 50% loss of sympathetic innervation)

Hemodynamic Instability: Intervention

First Line: Volume |Resuscitation (1-2 L)

Second line: Vasopressors- (dopamine/norepinephrine) to counter loss of sympathetic tone and provide chronotropic support to the heart

Hemodynamics and Cord Perfusion

Options:– Avoid hypotension – Maintain MAP 85-90mmHg for first 7 days

if possible

Bradycardia: Intervention

Prevention:– Avoid vagal stimulation– Hyperventilate and hyperoxygenate prior to

suctioning– Pre-medicate patients with known hypersensitivity

to vagal stimuli Treatment of Symptomatic Bradycardia:

– Atropine 0.5 - 1.0 mg IV

Neurological Classification

– Motor and sensory assessment – ASIA Impairment Scale (A-E)– Clinical Syndromes (patterns of incomplete injury)

Spinal Shock

An immediate loss of reflex function, called areflexia, below the level of injury

Signs: – Slow heart rate– Low blood pressure– Flaccid paralysis of skeletal muscles– Loss of somatic sensations– Urinary bladder dysfunction

Spinal shock may begin within an hour after injury and last from several minutes to several months, after which reflex activity gradually returns

Central Cord Syndrome

Usually involves a cervical lesion May result from cervical hyperextension causing

ischemic injury to the central part of the cord Motor weakness is more present in the upper limbs

then the lower limbs Patient is more likely to lose pain and temperature

sensation than proprioception Patient may complain of a burning feeling in the

upper limbs More commonly seen in older patients with cervical

arthritis or narrowing of the spinal cord

Brown-Sequard Syndrome

Results from an injury to only half of the spinal cord and is most noticed in the cervical region

Often caused by spinal cord tumours, trauma, or inflammation

Motor loss is evident on the same side as the injury to the spinal cord

Sensory loss is evident on the opposite side of the injury location (pain and temperature loss)

Bowel and bladder functions are usually normal

Person is normally able to walk although some bracing or stability devices may be required

Anterior Spinal Cord Syndrome

Usually results from compression of the artery that runs along the front of the spinal cord

Compression of SC may be from bone fragments or a large disc herniation

Patients with anterior spinal cord syndrome have a variable amount of motor function below the level of injury

Sensation to pain and temperature are lost while sensitivity to vibration and proprioception are preserved

Cauda Equina Syndrome:

Injury to the lumbosacral nerve roots w/ in the neurocanal resulting in areflexive bladder, bowel and lower limbs

Spine Imaging

the Asymptomatic Patient – Option - Xray not needed in alert, sober, compliant

patient without neck pain and tenderness or major distracting injuries

Symptomatic Patient – Standard – Ap lat and odontoid view– Option – discontinue protection after….

normal and adequate dynamic radiography, or normal MRI within 48hrs of injury, or at the discretion of treating MD

CT myelogram – Bony detail of fracture site, and anatomic relation of segment to spinal cord.

MRI – anterior discs, ligamentum flava & cord contusion.

GI System

Risk of aspiration is high d/t:

– cervical immobilization– local cervical soft tissue swelling– delayed gastric emptying

Parasympathetic reflex activity is altered, resulting in:

– decreased gut motility and

– often prolonged paralytic ileus

GI Intervention- Nasogastric tubeIV H2 blockers

GU Intervention – Catheterisation

Skin Intervention – *Remove spine board *Turn or reposition individuals with SCI initially

every 2 hours in the acute phase if the medical condition allows.

Pharmacologic Therapy

Methylprednisolone-controversial – 30mg/kg IV loading dose + 5.4 mg/kg/hr (over

23hrs) effective if administered within 8 hours of injury

– If initiated < 3hrs continue for 24 hrs, if 3-8 hrs after injury, continue for 48hrs (morbidity higher - increased sepsis and pneumonia)

Thromboprophylaxis - LMWH, discontinued at 3months

Secondary Interventions

Without mechanical compression on CT myelogram – External stabilisation

Mean arterial pressures are kept b/w 80-90 mmHg and CO kept ( N/ high N )

Dopamine infusion may be necessary

Anaesthesia Management

Pre op assessmentMedical historyPremedication and pt. EducationAirway managementPositioningFluid requirementsSpecial intraop requirements(wake up test)Post op pain and pulmonary toilet

Airway evaluationMP classification and range of neck mobility and elicitation of

pain/ neurological symptom Pulmonary evaluationDuring spinal shock (3 days – 6 wks) ABG- assess adequacy of ventilation, intubation if

hypoxemia or hypercapnia (on O2 mask)Chronic stage PFT and Chest X ray – Restrictive pattern (FEV1&FVC)

Severity of functional impairment related to – Angle of scoliosis, No of vertebrae, cephalad location of curve and loss of normal kyphosis.

Respiratory function should be optimised – Treating infectionBronchodilation Chest physiotherapy

Cardiac evaluationECG – myocardial ischemia Cardiovascular instability evidenced by hypotension,

hypertension, brady & arry. – assessment of cardiac reserve and to optimise circulatory volume according to cardiac function and peri. Vas. Tone.

Pacemaker – persistently bardycardic.High spinal cord injury – initially spinal shock,autonomic

dys,impaired LVF and later autonomic dysreflexia.

Neurological evaluationDocument preexisting deficitsNeurological dys may dictate intubation

tech,monitoring and choice of agents.

PharmacologyAltered P/K because of muscle wasting,inc volume

of distribution,dec serum albumin

Preop preparation

Hb, Hct, WBC and urinalysis

Other tests indicated by history

SE, BUN, Creatinine, PT,aPTT, Platelet count, ECG, Chest radiograph, ABG and PFT.

Echo – to assess LV function pulmonary artery pressures and stress echo in sedentary patients

Premedication If anxious IV midazolam Under supervision Atropine if HR < 70 – Dose 0.04mg/kg H2 receptor blocker/ PPIInduction Unnecessary/ contraindicated for unconscious,

recently injured patients with spinal cord trauma / those with severe shock.

Technique of intubationElective - fiberoptic intubation

Emergency – MILS with rapid sequence

Maintenance

Nitrous oxide, inhalation agent

Positioning

Goals

Adequate surgical exposure

Anatomic position of extremities & head

Avoid abdominal pressure

Adequate padding

Various positions

a) Prone

b) Supine

c) Sitting (obsolete

PRONE POSITION MOST COMMONLY USED

EYES:

Corneal abrasionOptic neuropathyRetinal artery occlusion

HEAD & NECK

Venous and lymphatic obstuction

ABDOMENImpaired ventilationDecreased CO

Monitoring

Neurological

Wake up test SSEP Transcutaneus MEP

PhysiologicalPulse oximetryContinuous ECG monitoring EtCo2CVPTemperatureUrine outputInvasive BPSwan Ganz catheter?

Post operative pain relief

• NSAIDS (IM,IV,P/R)• IV opiods (Intermitent / continuous infusion )• PCA

Post op critical care management

Indications for post op ventilation – Preexisting NM disorder Severe restrictive – VC <35% Obesity / RVF Prolonged surgery Surgical invasion of thoracic cavity Blood loss > 30ml/kg

post op contd Prepare for weaning

Adequate nutrition and metabolic state

Infection – May be masked(Poikilothermia)

Optimal fluid management

Treat mechanical impairment to breathing like abd distention, tight halo cast, position

Psychological preperation

Post op contd

Chest Physiotherapy – Postural drainage, chest wall percussion and vibration, tracheal suctioning and breathing exercises.

Cough – Glossopharyngeal breathing and huffing.

Breathing exercises

Perioperative complications of spine surgery

a) Airway obstruction : edema, hematoma,recurrent laryngeal nerve palsy.

b) Respiratory: motor paralysis and infection (pneumonia).c) Cardiovascular: hypotension, bradycardia, arrhythmias,

hypertension ( spinal cord injury, carotid sinus stimulation).

d) Neurological: Injury to nerve roots – as a result of direct surgicalmanipulationInjury to lower cranial nerves – VII, IX, X, XIIInjury to peripheral nerves - as a result of positioningInjury to spinal cord .

e) Vessel injury – vertebral and carotid artery during dissection

f) Tracheal and oesophageal injury

g) CSF leaks - due to tear of dural and arachnoid membranes can lead to meningitis,

pseudomeningocoele, permanent CSF fistula

h) DVT – seen in 30% of neurosurgical patients, especially those who had been paraplegic. Pulmonary embolism may occur

Outcome

Acute spinal injury who survive >24hrs,85%alive at 10years

Most common causes of death-pneumonia, non-ischemic heart disease (occult autonomic dysfn), suicide (lifelong impact of injury)

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