High Spinal and Total Spinal Block - Recognition and Management

Quick Answer

Immediate Recognition:

• Sensory level above T4 (high spinal) with respiratory symptoms
• Progressive ascending weakness (numbness in hands T1-T4, respiratory C3-C5)
• Severe hypotension with bradycardia (sympathetic blockade T1-L2)
• Loss of consciousness (if block reaches cranial levels)
• Dyspnoea, inability to speak (respiratory muscle paralysis)

Immediate Management (ABCD Approach):

A - Airway:

1. Call for help immediately
2. 100% oxygen via face mask (maintain SpO2)
3. Prepare for intubation - RSI if required (patient may be conscious initially)
4. Head-up 15-30 degrees (if not pregnant) - reduces cranial spread
5. Left lateral tilt for pregnant patients (aortocaval compression)

B - Breathing:

1. Assess respiratory effort
   • Can patient speak? Count to 10?
   • Observe diaphragmatic movement
   • Hand grip strength (C8-T1)
2. Support ventilation if needed
   • Face mask ventilation initially
   • Intubate if GCS <8 or respiratory failure
3. Avoid high FiO2 if spontaneous breathing (may worsen hypercapnia)

C - Circulation (CRITICAL):

1. Aggressive fluid loading (1-2L crystalloid)
2. Ephedrine 5-10 mg IV (mixed α/β agonist) - repeat every 2-3 minutes
3. Phenylephrine 50-100 mcg IV (if bradycardic, pure α)
4. Atropine 0.6 mg IV for severe bradycardia (HR <40 bpm)
5. Adrenaline 10-20 mcg IV (if cardiovascular collapse)
6. Noradrenaline infusion (0.05-0.5 mcg/kg/min) for refractory hypotension

D - Drugs/Disposition:

1. Lipid emulsion 20% - 1.5 mL/kg bolus (experimental, may bind local anaesthetic)
2. Continue monitoring in HDU/ICU
3. Block regression: Typically 2-4 hours (monitor for recovery)
4. Document incident and inform patient

Pregnant Patients Specific:

• Left lateral tilt mandatory after 20 weeks
• Fetal monitoring when viable (>24 weeks)
• Maternal safety priority (foetal survival depends on maternal survival)
• Consider early delivery if maternal condition critical

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Indigenous Health Considerations

High spinal and total spinal management present unique challenges for Aboriginal, Torres Strait Islander, and Māori populations, particularly given the high rates of obstetric anaesthesia where these complications most commonly occur. For Aboriginal and Torres Strait Islander women, pregnancy and childbirth occur within complex cultural frameworks where kinship, Country, and spiritual obligations intersect with medical care. High neuraxial blockades are reported as the leading cause of antepartum cardiac collapse in the UK, and Indigenous women may present with additional risk factors including higher rates of obesity, hypertensive disorders, and limited antenatal care access in remote communities.

Remote health service delivery significantly impacts management of high spinal emergencies. Regional hospitals serving Indigenous populations may lack immediate availability of senior anaesthetic support, advanced airway equipment, or ICU/HDU facilities for post-crisis monitoring. RFDS transfer protocols must include capacity for managing high spinal complications during retrieval, including airway management equipment, vasopressor infusions, and fetal monitoring for pregnant patients. Aboriginal Health Workers and midwives require training in early recognition of high spinal symptoms, particularly the importance of monitoring sensory levels and respiratory effort post-spinal anaesthesia.

Cultural safety considerations are paramount during crisis management. When high spinal occurs, the patient may be conscious but paralysed, creating profound psychological distress. Clear, calm communication through Aboriginal Liaison Officers is essential, explaining what is happening and reassuring the patient. Many Aboriginal women prefer female healthcare providers for obstetric care, and male providers should offer appropriate alternatives when possible. Family involvement follows collective decision-making processes, and emergency situations require rapid but culturally sensitive communication with extended kin.

Māori health considerations in Aotearoa New Zealand emphasise whānau-centred care during childbirth complications. Māori women experience disparities in maternal health outcomes, and high spinal management must incorporate tikanga (protocols) around birth and emergency situations. Whānau may wish to remain present during resuscitation, and Māori Health Workers provide essential cultural brokerage. Te Tiriti o Waitangi obligations require equitable care outcomes and Māori involvement in healthcare decision-making, including emergency protocols.

Healthcare providers must recognise the intersection of physiological vulnerability and cultural safety in Indigenous populations. Higher rates of obesity and cardiovascular disease may complicate hemodynamic management during high spinal episodes. Pre-operative assessment must be thorough given potential delayed presentation to care. Cultural protocols for managing emergencies should be established, including communication pathways, family involvement, and access to traditional birth support alongside Western medical interventions. Regional centres must have robust high spinal protocols with early recognition training, emergency drug availability, and clear transfer pathways when needed.

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Clinical Overview

Definition and Classification

High Spinal (High Neuraxial Block) is defined as a spinal or epidural block that achieves a sensory level higher than T4 (dermatome at the nipple line), resulting in sympathetic blockade of the cardiac accelerator fibres (T1-T4) and potential respiratory compromise if block extends to cervical levels (C3-C5). [1,2]

Total Spinal refers to the most severe form where the block ascends to cranial levels, causing:

• Complete sympathetic blockade (T1-L2)
• Respiratory muscle paralysis (C3-C5 phrenic nerve)
• Loss of consciousness (cranial nerve involvement)
• Cardiovascular collapse [3,4]

Classification by Sensory Level: [5,6]

Epidemiology

Incidence: [7,8]

• High spinal (above T4): 0.5-1.5% of spinal anaesthetics
• Total spinal: 0.01-0.1% (rare but potentially fatal)
• Obstetric population: Higher incidence due to:
  • Pre-existing epidural catheter migration
  • Combined spinal-epidural techniques
  • Increased sensitivity in pregnancy
  • Compressed epidural space

Risk Factors: [9,10]

Patient Factors:

• Pregnancy: Reduced CSF volume, compressed epidural space
• Short stature: Standard doses reach higher levels
• Obesity: Epidural venous engorgement, reduced CSF volume
• Extremes of age: Variable CSF volume
• Previous spinal surgery: Altered anatomy

Technical Factors:

• Excessive dose: Above recommended for patient height/weight
• Intrathecal migration of epidural catheter: Most common cause of total spinal
• Injection pressure: High-pressure injection (especially with CSE)
• Position: Head-down (Trendelenburg) promotes cranial spread
• Baricity of local anaesthetic: Heavy solutions sink, light solutions rise

High-Risk Scenarios: [11,12]

• Cesarean section after labour epidural (migration)
• Conversion from epidural to spinal for urgent CS
• Combined spinal-epidural with intrathecal catheter
• Repeated spinal attempts
• Obstetric patients (physiological changes)

Pathophysiology

Sympathetic Blockade: [13,14]

T1-T4 Cardiac Fibers:

• Blockade of cardiac accelerator fibres
• Unopposed vagal tone
• Bradycardia: Can be severe (HR 30-40 bpm)
• Reduced contractility: β1-blockade effect
• Vasodilation: Loss of vascular tone below block level

T5-L2 Distribution:

• Arteriolar and venous dilation
• Venous pooling (dependent areas)
• Reduced venous return (preload)
• Decreased cardiac output
• Hypotension (often severe)

Respiratory Effects: [15,16]

C3-C5 (Phrenic Nerve - Diaphragm):

• Complete respiratory paralysis if bilateral block
• Loss of main inspiratory muscle
• Requires mechanical ventilation

C5-C8 (Accessory Muscles):

• Intercostal muscle paralysis
• Reduced expiratory reserve
• Impaired cough
• Compensatory use of diaphragm

Above C3 (Brainstem):

• Loss of consciousness
• Medullary respiratory centre depression
• Complete cardiovascular collapse

Pharmacokinetic Factors: [17,18]

Pregnancy-Related Changes:

• Reduced CSF volume: 30-40% reduction (epidural venous engorgement)
• Increased CSF pressure: Compressed dural sac
• Increased sensitivity to local anaesthetics: Progesterone effect
• Aortocaval compression: Supine hypotension syndrome
• Altered protein binding: Less protein binding of local anaesthetic

Baricity Effects:

• Hyperbaric (heavy): Sinks to dependent areas (sitting/supine with head-down)
• Isobaric: Stays at injection level
• Hypobaric (light): Rises to non-dependent areas

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Recognition and Diagnosis

Clinical Signs and Symptoms

Progressive Stages of High Spinal: [19,20]

Stage 1 - Cardiovascular (T1-T4 block):

• Hypotension: Often severe (systolic BP <80 mmHg)
• Bradycardia: Sinus bradycardia, heart block possible
• Nausea/vomiting: Common (gut ischaemia, vagal stimulation)
• Anxiety: Patient aware but feeling unwell

Stage 2 - Respiratory (C5-C8 block):

• Numbness in hands: (C8-T1 dermatomes)
• Shortness of breath: Unable to take deep breath
• Weakness in arms: Unable to lift against gravity
• Speaking difficulty: Cannot count >10, slurred speech
• Shallow breathing: Accessory muscle weakness

Stage 3 - Total Spinal (C3-C5 block):

• Complete respiratory failure: Cannot breathe
• Loss of consciousness: If block reaches brainstem
• Pupil changes: May dilate (loss of sympathetic tone)
• Cardiovascular collapse: Severe bradycardia/asystole

Diagnostic Features: [21,22]

Sensory Level Assessment:

1. Pinprick testing: Map dermatome level
2. Touch sensation: Less reliable than pinprick
3. Temperature: Ice cube test
4. Proprioception: Joint position sense

Motor Block Assessment:

1. Bromage score: 0=none, 1=able to flex knees, 2=able to flex ankles, 3=unable to move legs
2. Hand grip strength: C8-T1 function
3. Shoulder shrug: C5 function
4. Diaphragmatic movement: Observation, palpation

Respiratory Assessment: [23,24]

• SpO2 monitoring: Continuous
• Respiratory rate: May be normal initially, then falls
• Auscultation: Breath sounds present initially
• EtCO2 (if intubated): Monitor for respiratory depression
• Arterial blood gas: If respiratory failure suspected

Hemodynamic Monitoring: [25,26]

• Continuous BP: Arterial line if severe
• Heart rate/rhythm: ECG monitoring essential
• CVP: If available (assess preload)
• Cardiac output: Rarely measured, inferred from BP/HR

Differential Diagnosis

Conditions Mimicking High Spinal: [27,28]

Key Distinguishing Feature: High spinal is level-dependent with ascending sensory/motor block Other conditions are not level-dependent (systemic effects)

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Acute Management

Immediate Response Algorithm

STEP 1: Recognition and Team Alert (30 seconds) [29,30]

• Confirm sensory level above T4
• Assess respiratory effort
• Call for help: "High spinal - need assistance"
• Position patient appropriately

STEP 2: Positioning (CRITICAL) [31,32]

Non-Pregnant Patients:

• Head-up 15-30 degrees (reduces cranial spread)
• Lateral position if vomiting risk
• Avoid Trendelenburg (worsens block)

Pregnant Patients (≥20 weeks):

• Left lateral tilt (uterine displacement)
• 15-30 degree head-up if tolerated
• Manual uterine displacement if tilt inadequate
• Fetal monitoring if viable (>24 weeks)

STEP 3: Airway Management [33,34]

If Patient Conscious and Breathing:

1. 100% oxygen via face mask
2. Reassurance - explain what is happening
3. Continuous monitoring: SpO2, respiratory rate, EtCO2
4. Prepare for intubation: Equipment ready
5. Intubation triggers:
   • GCS <8
   • Respiratory rate <8 or >30
   • SpO2 <90% on 100% O2
   • Inability to protect airway

Intubation Technique:

• Rapid sequence induction if full stomach (pregnant, emergency)
• Cricoid pressure mandatory in pregnancy
• Propofol/thiopentone - beware hypotension
• Rocuronium 1.2 mg/kg (fast onset)
• Etomidate if hemodynamically unstable
• Ketamine alternative (preserves BP, bronchodilator)

STEP 4: Cardiovascular Support [35,36,37]

Fluid Loading:

• Crystalloid 1-2L rapidly (maximize preload)
• Colloid if available
• Trendelenburg for legs only (elevate legs)
• BP cuff on arm (not leg - may be unreliable)

Vasopressors (Order of Preference):

1. Ephedrine (First Line):

• 5-10 mg IV bolus
• Repeat every 2-3 minutes
• Mixed α and β agonist
• Increases HR (treats bradycardia)
• Safe in pregnancy
• Max dose: 50-100 mg total

2. Phenylephrine:

• 50-100 mcg IV bolus
• Pure α-agonist
• Reflex bradycardia (avoid if HR <60)
• Good for isolated hypotension
• Infusion: 25-100 mcg/min

3. Adrenaline (Severe/Resistant):

• 10-20 mcg IV bolus (100-200 mcg IM if no IV)
• Both α and β effects
• For cardiovascular collapse
• Infusion: 0.05-0.5 mcg/kg/min

4. Noradrenaline (Refractory):

• Infusion 0.05-0.5 mcg/kg/min
• Pure α with weak β1
• Requires arterial line
• ICU/HDU setting

5. Atropine (Bradycardia):

• 0.6 mg IV (repeat to 3 mg total)
• For HR <40 or symptomatic bradycardia
• Unblocks vagal tone

STEP 5: Advanced Support [38,39]

Lipid Emulsion (20% Intralipid):

• Experimental for high spinal
• May bind local anaesthetic in CSF (theoretical)
• Dose: 1.5 mL/kg bolus over 2-3 minutes
• Follow with infusion 0.25 mL/kg/min
• Continue for 30-60 minutes
• Limited evidence but low risk

Other Considerations:

• Glycopyrrolate 0.2 mg IV: If excessive secretions
• Ondansetron 4 mg IV: For nausea/vomiting
• Sedation: If conscious but distressed (midazolam 1-2 mg IV)
• Temperature: Maintain normothermia

Monitoring and Ongoing Care

Essential Monitoring: [40,41]

• Continuous ECG (arrhythmia risk)
• Continuous BP (arterial line if unstable)
• Continuous SpO2
• Respiratory rate (if not ventilated)
• EtCO2 (if intubated)
• Temperature
• Urine output (catheterise)

Fetal Monitoring (Pregnant, >24 weeks): [42,43]

• Continuous CTG if maternal condition allows
• Category 3 CTG → urgent delivery if maternal condition stable
• Maternal resuscitation priority (foetal survival depends on mother)
• If maternal arrest → perimortem CS at 4 minutes

Neurological Assessment: [44,45]

• Serial sensory level testing (every 15-30 min)
• Motor block assessment
• Document regression
• Expected resolution: 2-4 hours (depending on drug)

Post-Crisis Management

Recovery Expectations: [46,47]

Typical Course:

• 0-2 hours: Peak block effect
• 2-4 hours: Gradual regression begins
• 4-6 hours: Return of motor function
• 6-12 hours: Full sensory recovery

Potential Complications: [48,49]

• Aspiration pneumonia: If vomiting/aspiration occurred
• Pressure injuries: If prolonged immobility
• Urinary retention: Common, catheterise
• Post-dural puncture headache: If dural puncture (25-30% risk)
• Psychological trauma: Patient may remember distress

Discharge Criteria: [50,51]

• Sensory level below T10
• Stable hemodynamics off vasopressors
• Adequate respiratory function (if not intubated)
• Clear neurological examination
• HDU/ICU observation for 12-24 hours if severe

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Special Considerations

Obstetric Patients

Unique Physiology: [52,53]

Why Higher Risk:

• Compressed epidural space: 30-40% reduced CSF volume
• Engorged epidural veins: Reduced space for LA spread
• Increased intra-abdominal pressure: Higher CSF pressure
• Progesterone effects: Increased neuronal sensitivity to LA
• Physiological anemia: Reduced oxygen reserve
• Aortocaval compression: Supine hypotension

Prevention Strategies: [54,55]

Labour Epidural to CS:

• Test dose: 3 mL lidocaine 2% + adrenaline before full dose
• Fractionated dosing: Small aliquots (3-5 mL) with assessment
• Aspiration: Before every injection (check for CSF)
• Dose reduction: 50% reduction if converting from labour epidural

CSE Technique:

• Intrathecal dose: Reduce by 20-30% in pregnancy
• Epidural catheter: Verify not intrathecal before topping up
• Time interval: Wait for spinal to settle before epidural top-up

Management Modifications: [56,57]

1. Position:

   • Left lateral tilt (15-30 degrees)
   • Manual uterine displacement if needed
   • Head-up 15-30 degrees (if tolerated)

2. Fetal Considerations:

   • Maternal hypotension >20% ↓utero-placental perfusion
   • Fetal bradycardia indicates uteroplacental insufficiency
   • May need urgent delivery if fetal compromise

3. Drug Considerations:

   • Ephedrine: Preferred (preserves uteroplacental flow)
   • Phenylephrine: Acceptable alternative (studies show safety)
   • Avoid: High-dose beta-blockers (atenolol)

Paediatric Patients

Unique Considerations: [58,59]

• Dose by weight/height: Critical calculation
• Higher spread: Relative to body size
• Toxicity risk: mg/kg dosing errors catastrophic
• Airway management: Smaller equipment, rapid desaturation

Management:

• Weight-based fluid bolus: 20 mL/kg
• Weight-based ephedrine: 0.1-0.2 mg/kg
• Weight-based atropine: 0.02 mg/kg (minimum 0.1 mg)
• Early intubation threshold (limited reserve)

Geriatric Patients

Age-Related Factors: [60,61]

• Reduced cardiac reserve: Limited response to stress
• Fixed cardiac output: Dependent on heart rate (SR)
• Baroreceptor sensitivity: Impaired, profound hypotension
• Reduced CSF volume: Higher spread for given dose
• Comorbidities: IHD, valvular disease, AF

Management:

• Reduced local anaesthetic doses
• Aggressive early support
• Lower threshold for arterial line
• Consider pre-operative optimization

Cardiac Disease

High-Risk Patients: [62,63]

Aortic Stenosis:

• Fixed output - dependent on preload
• Hypotension poorly tolerated
• Avoid tachycardia (reduces filling time)
• May need pre-emptive invasive monitoring

Cardiomyopathy:

• Reduced contractility
• Poor response to fluids
• Early inotropic support
• Consider PAC (pulmonary artery catheter)

Ischaemic Heart Disease:

• Tachycardia increases oxygen demand
• Hypotension reduces coronary perfusion
• Risk of ischaemia/infarction
• Maintain coronary perfusion pressure

Indigenous Health Considerations

Note: This section expands on the Quick Answer section above for comprehensive cultural safety training.

Aboriginal and Torres Strait Islander Maternal Health: [64,65,66]

Health Disparities:

• Higher maternal mortality compared to non-Indigenous
• Limited antenatal care access in remote communities
• Higher rates of obesity complicating neuraxial techniques
• Increased hypertensive disorders (pre-eclampsia)
• Higher emergency CS rates (less planned birth)

Implications for High Spinal Risk:

1. Emergency situations: Higher likelihood of unplanned procedures
2. Technique urgency: Time pressure may compromise safety
3. Co-morbidity burden: Complex physiology (obesity + hypertension)
4. Communication challenges: May affect informed consent process

Cultural Safety in Obstetric Crisis: [67,68,69]

Birth as Cultural Event:

• Childbirth is sacred in many Aboriginal cultures
• Connection to Country and family essential
• Medical complications interrupt cultural protocols
• Sorry Business implications if adverse outcomes

During High Spinal Emergency:

• Communication: Clear explanation via ALO/interpreter
• Family involvement: Extended kinship decision-making
• Gender considerations: Many women prefer female providers
• Traditional birth practices: Where possible, accommodate

Post-Crisis Support: [70,71]

• Access to Aboriginal midwives and Health Workers
• Extended family visiting policies
• Sorry Business protocols if needed
• Connection to Aboriginal Medical Services for follow-up
• Trauma-informed care recognizing historical obstetric violence

Māori Obstetric Health: [72,73,74]

Māori Maternity Disparities:

• Higher rates of maternal obesity
• Increased gestational diabetes
• Greater emergency intervention rates
• Significant health system barriers

Te Tiriti o Waitangi in Maternity Care:

• Partnership in care decisions
• Māori workforce involvement
• Culturally safe care environments

Whānau-Centred Crisis Management: [75,76]

During High Spinal:

• Whānau presence and support
• Clear communication in plain language
• Karakia (prayers) if requested
• Māori Health Worker support

Birth and Emergency:

• Tikanga (protocols) around birth complications
• Whenua (placenta) considerations even in emergencies
• Connection to whānau, hapū, iwi identity
• Traditional healing alongside medical care

Systemic Considerations: [77,78,79]

Access to Services:

• Rural Māori may travel far for maternity care
• Cultural dislocation when birthing away from home
• Limited Māori workforce in many regions
• Institutional racism affecting care quality

Quality Improvement:

• Māori-led maternity care models
• Cultural safety training mandatory
• Data collection on Indigenous outcomes
• Accountability for equitable care

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ANZCA Exam Focus

Written Examination (SAQ)

High-Yield Topics:

1. Mechanism of hypotension in spinal anaesthesia

   • Sympathetic blockade T1-L2
   • Venous pooling, reduced preload
   • Bradycardia from T1-T4 cardiac block

2. Pharmacological management hierarchy

   • Ephedrine first line (mixed α/β, ↑HR)
   • Phenylephrine pure α (watch bradycardia)
   • Adrenaline for collapse
   • Atropine for severe bradycardia

3. Obstetric modifications

   • Left lateral tilt (aortocaval compression)
   • Reduced LA doses (pregnancy physiology)
   • Ephedrine preserves uteroplacental flow
   • Fetal monitoring considerations

4. Differential diagnosis

   • High spinal vs LAST vs anaphylaxis
   • Level-dependent vs systemic effects

Common SAQ Scenarios:

Scenario 1: "During spinal anaesthesia for cesarean section, the patient becomes profoundly hypotensive (BP 60/40) with a heart rate of 40 bpm. Describe your management. (20 marks)"

Scenario 2: "A patient who received spinal anaesthesia for knee surgery complains of difficulty breathing and numbness in their hands. The sensory level is to C5. Outline your assessment and management. (15 marks)"

Viva Voce Examinations

Expected Viva Themes:

Theme 1: Recognition

• "You have just performed a spinal anaesthetic. The patient complains of difficulty breathing. What do you do?"
  • Key points: Check level, assess respiratory effort, call for help

Theme 2: Management

• "Describe your management of severe hypotension and bradycardia following spinal anaesthesia."
  • Key points: Position, fluids, ephedrine/phenylephrine, atropine

Theme 3: Obstetric Context

• "How would you manage a high spinal in a pregnant patient at 36 weeks gestation?"
  • Key points: Left tilt, fetal monitoring, ephedrine preference, possible delivery

Theme 4: Prevention

• "What measures can prevent high spinal during conversion of labour epidural to cesarean section?"
  • Key points: Test dose, fractionated dosing, aspiration, dose reduction

Viva Scenario Example

Examiner: "You have performed a spinal anaesthetic for cesarean section. Five minutes later the patient complains of feeling faint and you note the blood pressure is 70/40 with heart rate 45. What is your immediate management?"

Candidate Response Framework:

1. Immediate Assessment:

   • "I would first ensure left lateral tilt for uterine displacement"
   • "Call for help - 'High spinal, need assistance'"
   • "Check sensory level - likely above T4"

2. Cardiovascular Support:

   • "Rapid fluid loading - 1-2L crystalloid"
   • "Ephedrine 5-10 mg IV bolus, repeat as needed"
   • "If bradycardia severe, atropine 0.6 mg IV"
   • "Adrenaline if cardiovascular collapse"

3. Respiratory Support:

   • "100% oxygen via face mask"
   • "Assess ability to speak, take deep breath"
   • "Prepare for intubation if respiratory compromise"

4. Fetal Considerations:

   • "Apply fetal monitoring if viable"
   • "Urgent delivery if fetal compromise"
   • "Maternal resuscitation is priority"

Examiner Follow-up: "The patient has become unconscious and stopped breathing. What now?"

Candidate: "I would secure the airway with rapid sequence intubation using cricoid pressure, maintain left lateral tilt, ensure 100% oxygen, continue fluid resuscitation and vasopressor support, and consider whether urgent delivery is needed for fetal survival."

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Short Answer Questions

SAQ 1: High Spinal Management

Question: (20 marks) A 35-year-old patient undergoing spinal anaesthesia for cesarean section becomes profoundly hypotensive (BP 62/38 mmHg) with a heart rate of 42 bpm five minutes after injection. The patient complains of difficulty breathing and has lost sensation to the shoulders.

a) What is the diagnosis? What features suggest this is a high spinal rather than other causes of hypotension? (5 marks)

b) Describe your immediate management. (10 marks)

c) What specific considerations apply to the pregnant patient in this situation? (5 marks)

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Model Answer:

a) Diagnosis and Distinguishing Features (5 marks):

Diagnosis: High spinal block (likely total spinal) [1 mark]

Distinguishing Features:

1. Level-dependent symptoms: Sensory level to shoulders (C3-C5) indicates high block [1 mark]
2. Bradycardia + hypotension: Sympathetic blockade T1-T4 affecting cardiac accelerator fibres [1 mark]
3. Respiratory symptoms: Difficulty breathing from intercostal/diaphragmatic blockade [1 mark]
4. Timing: Occurs after spinal injection, not immediately (distinguishes from anaphylaxis) [1 mark]

b) Immediate Management (10 marks):

Positioning (2 marks):

1. Left lateral tilt (15-30 degrees) for uterine displacement
2. Head-up 15-30 degrees (reduces cranial spread of block)
3. Call for help immediately

Cardiovascular Support (5 marks): 4. Aggressive fluid loading: 1-2L crystalloid rapidly [1 mark] 5. Ephedrine 5-10 mg IV bolus, repeat every 2-3 minutes [1 mark]

• Mixed α/β agonist, increases heart rate

6. Atropine 0.6 mg IV (for severe bradycardia HR <40) [1 mark]
7. Adrenaline 10-20 mcg IV if cardiovascular collapse [1 mark]
8. Noradrenaline infusion (0.05-0.5 mcg/kg/min) if refractory [1 mark]

Respiratory Support (2 marks): 9. 100% oxygen via face mask 10. Assess respiratory effort (can they speak?) 11. Prepare for intubation if respiratory failure (GCS <8, RR <8)

Other (1 mark): 12. Continuous monitoring: ECG, BP, SpO2 13. Fetal monitoring if viable (>24 weeks)

c) Pregnancy-Specific Considerations (5 marks):

1. Aortocaval compression: Must maintain left lateral tilt to prevent supine hypotension syndrome [1 mark]
2. Fetal effects: Maternal hypotension >20% reduces utero-placental perfusion [1 mark]
3. Drug selection: Ephedrine preferred (preserves uterine blood flow) [1 mark]
4. Fetal monitoring: Continuous CTG when maternal condition allows [1 mark]
5. Delivery decision: If maternal arrest at >24 weeks, perimortem cesarean at 4 minutes [1 mark]
6. Aspiration risk: Full stomach - RSI with cricoid if intubation needed [1 mark]

(Any 5 points acceptable)

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SAQ 2: Prevention of High Spinal

Question: (15 marks) You are converting a labour epidural to spinal anaesthesia for urgent cesarean section.

a) List three risk factors for high spinal in this scenario. (3 marks)

b) Describe the technique to minimise risk of high spinal. (7 marks)

c) What is a "test dose" and why is it important? (5 marks)

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Model Answer:

a) Risk Factors (3 marks):

1. Intrathecal catheter migration: Labour epidural catheter may have migrated into subarachnoid space [1 mark]
2. Compressed epidural space: Pregnancy reduces CSF volume by 30-40% [1 mark]
3. Increased sensitivity: Progesterone increases neuronal sensitivity to local anaesthetic [1 mark]
4. Time pressure: Urgent CS may lead to rushed technique [1 mark]
5. Higher spread in pregnancy: Standard doses reach higher sensory levels [1 mark]

(Any 3 acceptable)

b) Technique to Minimise Risk (7 marks):

1. Test dose: Inject 3 mL lidocaine 2% + 1:200,000 adrenaline [1 mark]
   • Rapid sensory block indicates intrathecal catheter
2. Aspiration: Attempt aspiration through catheter before every injection [1 mark]
   • CSF return indicates intrathecal placement
3. Fractionated dosing: Give local anaesthetic in small aliquots (3-5 mL) [1 mark]
   • Assess between doses for level and block density
4. Dose reduction: Use 50% of standard spinal dose [1 mark]
   • 1.5-2 mL hyperbaric bupivacaine 0.5% instead of 2.5-3 mL
5. Check sensory level: Test block height after each increment [1 mark]
6. Avoid Trendelenburg: Head-up position if possible [1 mark]
7. Alternative: Consider combined spinal-epidural (CSE) with reduced intrathecal dose [1 mark]

c) Test Dose (5 marks):

Definition: [1 mark]

• Small volume (3 mL) of local anaesthetic with adrenaline injected via epidural catheter to test for intravascular or intrathecal placement

Purpose and Interpretation: [2 marks]

• Intrathecal: Rapid onset of sensory block within 2-5 minutes (indicates catheter in subarachnoid space)
• Intravascular: Tachycardia within 30 seconds (indicates IV catheter placement)

Importance: [2 marks]

• Prevents high spinal by detecting intrathecal catheter before full dose given
• Prevents systemic toxicity by detecting IV catheter
• Mandatory safety check before any epidural top-up
• Particularly important when converting labour epidural to surgical anaesthesia

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SAQ 3: Total Spinal vs Local Anaesthetic Toxicity

Question: (15 marks) Compare and contrast the features of total spinal block and local anaesthetic systemic toxicity (LAST). Include mechanisms, clinical features, and management differences.

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Model Answer:

Mechanisms (5 marks):

Clinical Features (5 marks):

Management Differences (5 marks):

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References

1. Sivanandan S, Surendran A. Management of total spinal block in obstetrics. Update Anaesth. 2019;34:18-24.

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