2.5 Regional and local anaesthesia
RA_1.2 Outline the pre-operative assessment and preparation of the patient before performing a central neuraxial block
Pre-Operative Assessment and Preparation for Central Neuraxial Block
A thorough pre-operative assessment ensures the safety and success of a central neuraxial block (spinal or epidural), optimizing patient outcomes while minimizing complications.
1. Patient History
Medical History
Identify absolute contraindications, including:
Coagulopathy or bleeding disorders (e.g., thrombocytopenia, hemophilia).
Active infection at the planned insertion site or systemic sepsis.
Severe hypovolemia or hemodynamic instability (increased risk of cardiovascular collapse).
Raised intracranial pressure (ICP) (risk of brainstem herniation).
Identify relative contraindications requiring caution:
Spinal abnormalities (e.g., scoliosis, spinal stenosis, prior back surgery, ankylosing spondylitis).
Neurological conditions (e.g., multiple sclerosis, peripheral neuropathies—potential worsening of symptoms).
Severe aortic/mitral stenosis (risk of profound hypotension due to sympathetic blockade).
Medication Review
Anticoagulants and antiplatelets:
Follow ASRA (American Society of Regional Anesthesia) guidelines for perioperative management.
Warfarin: INR should be <1.5 before proceeding.
DOACs (e.g., rivaroxaban, apixaban): Ensure appropriate washout period before block.
Clopidogrel/ticagrelor: Require 5–7 days of discontinuation before block.
Low molecular weight heparin (LMWH): Timing of last dose matters (prophylactic vs. therapeutic dosing).
Allergy and Drug Sensitivities
Ensure no allergy to local anaesthetics or adjuvants (e.g., chlorhexidine, opioids, clonidine).
Anaesthetic History
Identify previous difficulties with neuraxial blocks (e.g., failed or traumatic attempts, post-dural puncture headache).
Document any adverse reactions (e.g., LAST—local anaesthetic systemic toxicity).
2. Physical Examination
General Systemic Assessment
Conduct a standard pre-anaesthetic assessment:
Cardiovascular: Rule out severe AS/MS (risk of profound hypotension).
Respiratory: Identify conditions that may impair respiratory function in case of high neuraxial spread (e.g., morbid obesity, COPD).
Spinal Examination
Inspect and palpate for:
Visible deformities (e.g., kyphosis, scoliosis, surgical scars).
Localized infection, erythema, or swelling.
Palpation of interspaces (L3-L4, L4-L5) for block placement.
Mobility and positioning considerations (e.g., severe arthritis limiting positioning).
3. Laboratory Investigations (If Indicated)
Coagulation Profile
Platelet count: If <75,000, caution advised.
INR/PT/aPTT: If on anticoagulation therapy or with liver dysfunction.
Other Investigations (Case-by-Case Basis)
Renal function tests (eGFR, creatinine): If chronic kidney disease, as impaired clearance affects drug metabolism.
Blood glucose: If diabetic (avoid hypoglycemia, ensure stable levels perioperatively).
4. Patient Optimization
Volume Status
Correct hypovolemia (e.g., IV fluids if NPO) to reduce the risk of profound post-block hypotension.
Medication Adjustments
Hold anticoagulants per guidelines.
Continue antihypertensives, except ACE inhibitors and ARBs (reduce risk of severe hypotension post-block).
Consider pre-medication with anxiolytics (e.g., midazolam) if anxious, while maintaining cooperation.
5. Patient Education and Consent
Explain the Procedure
Describe the technique, expected onset, and duration of the block.
Discuss Risks and Benefits
Benefits: Pain relief, reduced opioid use, fewer systemic side effects.
Risks:
Common: Hypotension, headache, urinary retention.
Rare but serious: Nerve injury, epidural hematoma, infection, high spinal block.
Address any patient concerns and set realistic expectations.
Informed Consent
Obtain written consent where necessary.
Ensure patient understands alternative options (e.g., general anaesthesia).
6. Equipment and Monitoring Setup
Preparation of Equipment
Sterile tray with local anaesthetic, syringes, needles, and adjuvants.
Resuscitation drugs:
Ephedrine/phenylephrine for hypotension.
Atropine/glycopyrrolate for bradycardia.
Lipid emulsion (for LAST management).
Standard Monitoring
IV access secured before the procedure.
Attach standard ASA monitors:
ECG for arrhythmia detection.
Non-invasive BP for hypotension monitoring.
Pulse oximetry to track oxygenation.
Emergency Preparedness
Ensure airway equipment is immediately available in case of high spinal leading to respiratory depression.
If an epidural is being placed, verify that a test dose is prepared to rule out intrathecal or intravascular placement.
Conclusion
A comprehensive pre-operative assessment and meticulous preparation are crucial to ensuring the success and safety of a central neuraxial block. Proper risk stratification, patient education, and equipment readiness minimize complications and optimize perioperative outcomes.
RA_1.5 Describe how to assess the adequacy of a central neuraxial block and manage an inadequate block
Assessing the Adequacy of a Central Neuraxial Block
A thorough assessment of a central neuraxial block (spinal or epidural) is essential to ensure adequate analgesia and anesthesia for the planned procedure. This involves evaluating sensory, motor, and autonomic blockade, as well as confirming symmetry and adequacy of spread.
1. Sensory Blockade
Objective: Determine the level and extent of sensory block to ensure adequate surgical anesthesia.
Dermatomal Level Assessment:
Use cold stimulus (ice, ethyl chloride spray) or pinprick to map sensory loss.
Compare sensation to a reference area (e.g., forehead) to detect changes.
Confirm that the block reaches the required dermatome:
T4 for cesarean section
T6–T8 for upper abdominal surgery
T10 for lower abdominal surgery
T12–L1 for inguinal and perineal procedures
L2–S2 for lower limb surgery
Extent of Block:
Ensure coverage includes both the surgical incision site and any expected pain referral areas.
Confirm depth of block—superficial anesthesia may be inadequate for deep tissue surgery.
2. Motor Blockade
Objective: Evaluate the degree of motor impairment to assess block depth and consistency.
Bromage Scale for Lower Limb Motor Function:
0 – Full movement (no block)
1 – Unable to lift extended leg; hip flexion blocked
2 – Unable to flex knee; hip and knee blocked
3 – No movement at all (complete motor block)
Upper Limb Motor Function (for high spinal/epidural blocks):
Assess hand grip and elbow flexion (C5–C7 involvement).
Unexpected upper limb weakness may indicate excessive cephalad spread.
Procedure-Specific Considerations:
Some surgeries (e.g., orthopedic lower limb procedures) require a dense motor block, while labor analgesia should ideally preserve motor function.
3. Autonomic Blockade
Objective: Detect sympathetic blockade, which contributes to hypotension and bradycardia.
Signs of Sympathetic Block:
Hypotension due to arterial and venous vasodilation (T1–L2 block).
Bradycardia if the block extends to T1–T4, affecting cardiac sympathetic fibers.
Warm, flushed skin in blocked dermatomes.
Management:
Treat hypotension with IV fluids and vasopressors (e.g., phenylephrine, ephedrine).
Monitor heart rate—excessive bradycardia may require atropine or glycopyrrolate.
4. Symmetry of Block
Objective: Ensure uniform distribution of local anesthetic.
Bilateral Assessment:
Compare sensory and motor block on both sides.
Asymmetry suggests patchy spread or maldistribution (common in epidurals).
Corrective Measures:
Reposition patient to encourage better spread (e.g., lateral positioning if unilateral block).
Manipulate epidural catheter (withdraw or advance) if an epidural block is asymmetric.
Managing an Inadequate Block
If a block is insufficient for surgical anesthesia or analgesia, immediate corrective actions are required.
1. Identify the Problem
Partial Block: Incomplete sensory/motor blockade with inadequate anesthesia.
Asymmetric Block: Unequal distribution of anesthesia, affecting one side more than the other.
Failed Block: No effect despite appropriate technique and dosing.
2. Immediate Management Strategies
Partial or Insufficient Block:
For Epidural Blocks:
Administer a top-up dose of local anesthetic via the catheter.
Use a higher concentration (e.g., increase from bupivacaine 0.125% to 0.25%).
Adjust patient positioning to promote cephalad or lateral spread.
Consider catheter manipulation (withdraw slightly to avoid a potential one-sided epidural).
For Spinal Blocks:
Wait and reassess (if early after administration, block may still be spreading).
Re-dose if using a continuous spinal catheter.
Convert to epidural or general anesthesia if the block remains inadequate.
Asymmetric Block:
For Epidural Blocks:
Reposition the patient to facilitate spread toward the unblocked side.
Pull back or advance the epidural catheter slightly.
Administer a small bolus to test if local anesthetic spreads appropriately.
For Spinal Blocks:
If unilateral, attempt lateral positioning on the unblocked side.
If persistent, consider re-dosing or conversion to general anesthesia.
Failed Block:
For Epidural:
Confirm catheter placement (aspiration, test dose, incremental dosing).
Replace the catheter at a different level if no effect.
Convert to spinal or general anesthesia if necessary.
For Spinal:
If there is no effect at all, consider:
Incorrect placement (e.g., intrathecal catheter failure).
Maldistribution (e.g., high CSF flow washing away drug).
Reattempt spinal at a different interspace or convert to general anesthesia.
3. Pharmacological Interventions
To enhance block efficacy, consider:
Higher local anesthetic concentrations (e.g., 0.5% bupivacaine instead of 0.25%).
Adjuvants:
Opioids (e.g., fentanyl, morphine) prolong sensory block.
Clonidine or dexmedetomidine enhance both sensory and motor blockade.
Sodium bicarbonate (for epidurals) speeds onset by alkalinizing the local anesthetic.
4. Monitoring and Reassessment
After any intervention:
Reassess sensory and motor block every 5–10 minutes.
Ensure patient comfort and hemodynamic stability.
Confirm adequacy before proceeding with surgery.
5. Documentation and Postoperative Follow-Up
Record:
Level of block achieved.
Interventions performed.
Patient response and final outcome.
Postoperative considerations:
Monitor for post-dural puncture headache (PDPH) if dural puncture occurred.
Assess for neurological complications, especially in prolonged epidurals.
Ensure adequate postoperative analgesia (e.g., multimodal analgesia, PCA opioids).
Conclusion
A structured, systematic approach to assessing and managing a central neuraxial block ensures effective anesthesia and patient safety. Prompt identification and intervention in cases of inadequate blockade help minimize delays and avoid unnecessary conversion to general anesthesia.
RA_1.6 Discuss the appropriate use of intraoperative anxiolytic sedation to supplement central neuraxial block
Appropriate Use of Intraoperative Anxiolytic Sedation in Central Neuraxial Block
1. Indications
Patient Comfort:
To reduce anxiety and distress in awake patients undergoing surgery.
Useful in patients uncomfortable with the operative environment (e.g., noise, conversations, surgical sensations).
Immobilization:
Facilitates patient cooperation and minimizes movement during procedures.
Essential in surgeries requiring a high degree of precision (e.g., orthopedics, vascular surgery).
Extended Duration of Surgery:
Prolonged procedures may require sedation to reduce fatigue and discomfort.
2. Considerations for Use
Patient Factors:
Anxiety Levels: Tailored to patient’s psychological needs; avoid over-sedation.
Coexisting Conditions: Caution in patients with respiratory disease, obstructive sleep apnea, or frailty.
Cognitive Function: Avoid in patients with a risk of postoperative delirium.
Surgical Factors:
Nature of the procedure: Sedation is more likely needed in longer or more invasive surgeries.
Positioning requirements: Sedation may help tolerate uncomfortable positions (e.g., lithotomy).
Anesthetic Factors:
High spinal blocks or extended sensory levels may reduce the need for sedation.
Awareness of risks, such as masking symptoms of an inadequate block or high spinal anesthesia.
3. Agents Commonly Used
Midazolam (Benzodiazepine):
Provides anxiolysis, amnesia, and sedation.
Short-acting with titratable dosing.
Risks: Respiratory depression, oversedation in elderly or frail patients.
Propofol:
Effective for light to moderate sedation; rapid onset and recovery.
Provides better control and titration.
Risks: Hypotension, especially in hypovolemic or elderly patients.
Dexmedetomidine:
Sedation with minimal respiratory depression; maintains arousability.
Provides analgesia and sympatholysis.
Risks: Bradycardia, hypotension.
Fentanyl (Low Dose):
Provides sedation and supplemental analgesia.
Risks: Respiratory depression, nausea, or pruritus.
4. Risks and Precautions
Respiratory Depression:
Especially in obese patients or those with preexisting respiratory compromise.
Close monitoring with pulse oximetry and capnography.
Hemodynamic Instability:
Synergistic effects with neuraxial-induced sympathetic blockade can cause hypotension.
Gradual titration of sedatives is critical.
Masking of Symptoms:
Sedation may obscure patient complaints of discomfort or symptoms of high spinal block.
Maintain frequent communication with the patient during sedation.
Postoperative Delirium:
Minimize sedation in elderly or cognitively impaired patients to avoid exacerbation.
5. Monitoring and Best Practices
Standard Monitoring:
ECG, blood pressure, oxygen saturation, and level of consciousness.
Individualized Approach:
Minimal sedation for most cases; use deeper sedation only when necessary.
Titrate dose based on patient response and surgical requirements.
Team Communication:
Clear communication between anesthetist and surgeon to balance sedation depth and safety.
Summary
Intraoperative anxiolytic sedation can enhance patient comfort, cooperation, and surgical conditions when used judiciously during central neuraxial block. A careful selection of agents, vigilant monitoring, and a patient-centered approach minimize risks and optimize outcomes.
RA_1.7 Outline the assessment and management of minor and major complications associated with a central neuraxial block
Assessment and Management of Complications Associated with Central Neuraxial Block
1. Minor Complications
A. Hypotension
Assessment:
Early signs include dizziness, nausea, and reduced blood pressure (SBP <90 mmHg or a 20% drop from baseline).
Check for high spinal block or sympathetic blockade.
Management:
Administer IV fluids (crystalloid or colloid boluses).
Use vasopressors (e.g., phenylephrine or ephedrine) to maintain perfusion.
Monitor and treat bradycardia if present (e.g., atropine or glycopyrrolate).
B. Nausea and Vomiting
Assessment:
Often secondary to hypotension or unopposed vagal tone.
Rule out other causes like opioid use or visceral manipulation.
Management:
Correct underlying hypotension.
Administer antiemetics (e.g., ondansetron, metoclopramide).
C. Post-Dural Puncture Headache (PDPH)
Assessment:
Presents as a postural headache (worse on sitting or standing).
May be accompanied by nausea, neck stiffness, or tinnitus.
Management:
Conservative: Bed rest, hydration, caffeine.
Severe cases: Epidural blood patch.
D. Backache
Assessment:
Common, often due to needle trauma or prolonged positioning.
Management:
Reassurance and analgesia (e.g., paracetamol, NSAIDs).
2. Major Complications
A. High Spinal Block
Assessment:
Symptoms: Dyspnea, difficulty speaking, bradycardia, hypotension.
Signs: Progressive sensory and motor block extending to cervical levels.
Management:
Immediate airway support (oxygen, intubation if needed).
Hemodynamic support with fluids and vasopressors.
Stop further anesthetic administration.
B. Epidural Hematoma
Assessment:
Severe back pain, motor weakness, sensory loss, or bowel/bladder dysfunction.
Confirmed via urgent MRI or CT.
Management:
Emergency neurosurgical decompression within 6–12 hours of symptom onset.
C. Nerve Injury
Assessment:
Symptoms: Persistent sensory loss or motor weakness postoperatively.
Differentiate from transient effects of the block or positional injury.
Management:
Neurological consultation and imaging (MRI/CT) if symptoms persist.
Supportive care and physiotherapy for minor cases.
D. Infection (e.g., Meningitis, Abscess)
Assessment:
Fever, back pain, neurological signs (e.g., weakness, sensory changes).
Confirm with imaging or cerebrospinal fluid (CSF) analysis.
Management:
Antibiotic therapy for meningitis.
Surgical drainage for abscesses.
E. Cardiovascular Collapse
Assessment:
Severe hypotension, bradycardia, or asystole due to sympathetic blockade or vagal stimulation.
Management:
Immediate resuscitation (CPR if required).
Aggressive fluid resuscitation and vasopressors.
Atropine or epinephrine for bradycardia/asystole.
3. Prevention Strategies
Pre-procedure assessment: Identify high-risk patients (e.g., coagulopathies, infections).
Aseptic technique: Reduces risk of infection.
Monitoring: Continuous hemodynamic and neurological assessment during and after the block.
Patient positioning: Ensure proper alignment to reduce traumatic injury.
Dose titration: Minimize risk of high spinal block.
Summary
Central neuraxial blocks are generally safe but can lead to minor and major complications. Early recognition and prompt management of complications, along with preventive measures, are essential for optimizing patient outcomes.
RA_1.8 Describe post-anaesthesia instructions for patients following a central neuraxial block
Post-Anaesthesia Instructions for Patients Following a Central Neuraxial Block
Providing clear post-anaesthesia instructions ensures patient safety, optimal recovery, and early recognition of complications after a central neuraxial block (spinal or epidural).
1. General Overview
Explain that the block provides temporary pain relief, and its duration depends on the local anaesthetic and any additives used (e.g., spinal: 2–6 hours, epidural: variable, depending on infusion rate and concentration).
Reassure patients about common, transient side effects, such as numbness, tingling, or heaviness in the legs, and emphasize warning signs that require medical attention.
2. Activity and Mobility
Motor Recovery
Instruct patients to remain in bed until they regain full motor function to prevent falls or injury.
Encourage leg movement exercises in bed to facilitate circulation and recovery.
Assistance with Mobilization
When the block starts to wear off, patients should not attempt to stand unaided.
Encourage assisted first-time mobilization with nursing staff or a caregiver.
Positioning Considerations
If a post-dural puncture headache (PDPH) is suspected or at risk (e.g., large dural puncture, multiple attempts), recommend lying flat for a few hours to reduce headache severity.
3. Pain and Sensory Effects
Pain Relief and Transition to Oral Analgesia
Inform patients that pain relief will last for several hours and advise when to start oral pain medication before the block fully wears off to prevent breakthrough pain.
Recommend a multimodal analgesia approach (e.g., paracetamol, NSAIDs, or prescribed opioids) for ongoing pain control.
Residual Numbness or Tingling
Mild numbness, tingling, or heaviness in the legs is common and should resolve gradually.
If persistent (>24 hours) or worsening numbness occurs, the patient should seek medical review.
4. Monitoring and Red Flags
Patients should be educated on signs requiring urgent medical attention, including:
Neurological Symptoms
Persistent limb weakness (>6–8 hours post-block) or an inability to move the legs.
New-onset numbness, paraesthesia, or increasing sensory loss beyond the expected duration of the block.
Severe Pain or Headache
Severe back pain that persists or worsens over time.
Post-dural puncture headache (typically worse when sitting/standing, relieved when lying down).
If a headache occurs, advise hydration, caffeine intake, and lying flat. If severe, persistent, or associated with nausea/vomiting, contact a doctor as it may require an epidural blood patch.
Signs of Infection or Epidural Abscess (if epidural used)
Fever, redness, swelling, or pus at the injection site.
New or worsening back pain combined with fever or neurological deficits (urgent review needed).
Signs of Epidural Hematoma (Rare but Serious Complication)
Progressive weakness, numbness, or inability to walk hours after the block should raise concern.
New onset urinary retention or incontinence may indicate spinal cord compression—seek urgent medical attention.
5. Urinary Function
Urinary retention is common, particularly after spinal anaesthesia and in males.
Patients should attempt to urinate within 6–8 hours post-block.
If unable to urinate or experiencing significant bladder discomfort, seek assistance for catheterization if necessary.
6. Follow-Up and Emergency Contact
Provide clear instructions on who to contact (hospital, anaesthetic team, or emergency services) if concerning symptoms develop.
Consider scheduling a follow-up review for patients at higher risk of complications (e.g., those with pre-existing neurological conditions, difficult block placement, or prolonged epidural use).
7. Education and Reassurance
Explain the expected recovery timeline and reassure patients about the temporary nature of most side effects.
Encourage communication—patients should feel comfortable asking questions and voicing concerns about their recovery.
Conclusion
A structured approach to post-anaesthesia instructions enhances patient safety, comfort, and satisfaction while ensuring early recognition and management of potential complications.
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