Understanding Epidural Anesthesia
Epidural anesthesia is a versatile regional anesthesia technique involving catheter placement in the epidural space for continuous analgesia or anesthesia. This comprehensive guide covers essential knowledge for anesthesia residents.
Anatomical Considerations
The epidural space is a potential space between:
- Ligamentum flavum (anterior boundary)
- Dura mater (posterior boundary)
- Extends from foramen magnum to sacrococcygeal membrane
- Contains fat, blood vessels, and nerve roots
- Interspinous spaces (Tuffier's line at L4)
- Posterior superior iliac spines
- Spinous processes
Physiological Effects
- Sensory Blockade:
- Dose-dependent dermatomal coverage
- Progressive loss: Temperature → Pain → Touch → Proprioception
- Motor Blockade:
- Concentration-dependent (lower concentrations preserve motor function)
- Bromage scale assessment
- Sympathetic Blockade:
- Vasodilation → decreased systemic vascular resistance
- Potential hypotension (especially with thoracic epidurals)
Indications
- Obstetrics: Labor analgesia, cesarean delivery
- Postoperative Pain: Thoracic, abdominal, orthopedic surgeries
- Chronic Pain: Cancer pain, radiculopathy
- Surgical Anesthesia: Lower abdominal, pelvic, lower extremity procedures
- Vascular Procedures: Aortic surgery, peripheral vascular reconstructions
Contraindications
Absolute:
- Patient refusal
- Infection at insertion site
- Coagulopathy (INR >1.5, platelets <80,000, therapeutic anticoagulation)
- Increased ICP
- Severe hypovolemia
Relative:
- Spinal deformities
- Pre-existing neurological disorders
- Septicemia
- Uncooperative patient
Pharmacology
Common local anesthetics and dosing:
| Agent | Concentration (%) | Onset (min) | Duration (hr) |
|---|---|---|---|
| Bupivacaine | 0.0625-0.25 | 10-20 | 2-5 |
| Ropivacaine | 0.1-0.2 | 10-15 | 2-4 |
| Lidocaine | 1-2 | 5-15 | 1-1.5 |
Next Steps
Ready to master the technique? See our Step-by-Step Guide to Epidural Catheter Insertion
Learn about essential equipment in our Epidural Needles and Equipment guide.
Page 1 of 4
Epidural Catheter Insertion: Technique and Precision
Successful epidural placement requires meticulous technique and anatomical knowledge. This guide provides a detailed, step-by-step approach for anesthesia residents.
Pre-Procedure Preparation
- Patient Assessment:
- Verify coagulation status (platelets, INR, anticoagulants)
- Assess airway and cardiorespiratory status
- Obtain informed consent
- Establish IV access (18G or larger)
- Equipment Setup:
- Epidural tray with Tuohy needle
- Loss-of-resistance (LOR) syringe
- Test dose syringe (3 mL lidocaine 1.5% with epinephrine 1:200,000)
- Epidural catheter with filter
- Chlorhexidine solution, sterile drapes, gauze
- Monitoring equipment (ECG, NIBP, SpO₂)
- Positioning:
- Lateral decubitus: Knees to chest, spine parallel to edge of bed
- Sitting position: Feet on stool, leaning forward with curved back
- Ensure midline position and open interspaces
Step-by-Step Insertion Technique
- Landmark Identification:
- Palpate iliac crests → Tuffier's line (L4 spinous process)
- Mark L2-L3, L3-L4, or L4-L5 interspace
- Prepare wide area with chlorhexidine
- Local Anesthesia:
- Inject 3-5 mL lidocaine 1% at skin entry site
- Create subcutaneous wheal
- Anesthetize deeper tissues along planned needle path
- Needle Insertion:
- Hold Tuohy needle with stylet in place
- Insert midline at 90° to skin in all planes
- Advance through supraspinous and interspinous ligaments
- Attach LOR syringe with air or saline
- Identifying Epidural Space:
- Advance needle slowly while maintaining pressure on plunger
- Feel for characteristic "pop" at ligamentum flavum
- Confirm with sudden loss of resistance
- Aspirate to ensure no CSF or blood
- Catheter Insertion:
- Remove stylet from needle
- Insert epidural catheter through needle to 15-20 cm mark
- Advance catheter 3-5 cm beyond needle tip
- Hold needle steady while withdrawing catheter
- Needle Removal and Catheter Securing:
- Withdraw needle while stabilizing catheter
- Check catheter for CSF or blood flow
- Connect filter and secure with occlusive dressing
- Apply sterile tape to prevent catheter migration
- Test Dosing:
- Inject 3 mL lidocaine 1.5% with epinephrine 1:200,000
- Monitor for:
- Intravascular injection (tachycardia, hypertension)
- Intrathecal injection (rapid sensory/motor block)
- Systemic toxicity (tinnitus, metallic taste)
- Wait 3-5 minutes before administering therapeutic dose
Confirmation Techniques
- Loss of Resistance: Gold standard for space identification
- Hanging Drop: Alternative technique (less reliable)
- Ultrasound Guidance: Increasingly used for difficult anatomy
- Electrical Stimulation: Confirm catheter position
Documentation Essentials
- Needle type and gauge
- Interspace used
- Catheter depth at skin and distance beyond needle tip
- Loss of resistance medium (air/saline)
- Test dose response
- Any complications during insertion
Related Resources
Review the fundamentals in our Epidural Anesthesia Overview.
Understand your equipment in our Epidural Needles and Equipment guide.
Page 2 of 4
Epidural Equipment: Needles, Catheters, and Accessories
Understanding epidural equipment is fundamental to safe and effective practice. This guide details the needles, catheters, and accessories used in epidural anesthesia.
Epidural Needles
Tuohy Needle
The standard needle for epidural insertion:
- Design: Hub, shaft, and curved, blunt tip with directional port
- Function:
- Curved tip helps navigate ligaments
- Directional port guides catheter placement
- Blunt tip reduces dural puncture risk
- Sizes:
- 16G-18G for adults
- 19G-20G for pediatric patients
- Length: 8-10 cm (standard), 15 cm (obese patients)
- Key Features:
- Wing hubs for better grip and control
- Depth markings on shaft
- Color-coded by gauge
Weiss Needle
Alternative needle design:
- Shorter, sharper curve than Tuohy
- Used primarily for thoracic epidurals
- Less commonly used today
Hustead Needle
Modified Tuohy design:
- Longer, more gradual curve
- Designed for easier catheter passage
- Popular for obstetric anesthesia
Catheter Types
Standard Epidural Catheters
- Material: Polyurethane or nylon
- Size: 19G-20G for adults, 22G-24G for pediatrics
- Length: 70-100 cm
- Design:
- Single end-hole (open tip)
- Multiple side holes (closed tip)
- Wire-reinforced for kink resistance
Specialized Catheters
- Spring-Wound: Enhanced flexibility and kink resistance
- Programmable: For patient-controlled epidural analgesia (PCEA)
- Combined Spinal-Epidural (CSE): Small gauge spinal needle through epidural needle
- Thoracic Catheters: Softer, more flexible for thoracic placement
Loss of Resistance (LOR) Devices
Syringe-Based Systems
- Air-Filled:
- Traditional method
- Risk of venous air embolism
- Less reliable in obese patients
- Saline-Filled:
- Preferred modern technique
- More reliable tactile feedback
- No embolism risk
- Bubble Technique: Small air bubble in saline for enhanced sensitivity
Electronic LOR Devices
- Computerized pressure monitoring
- Visual and auditory feedback
- Particularly useful for teaching
Accessories
Filtration Systems
- Bacterial Filters: 0.2 micron filters prevent contamination
- Particulate Filters: Prevent drug particle injection
- Combined Filters: Both bacterial and particulate filtration
Infusion Devices
- Gravity Infusion: Simple drip sets
- Electronic Pumps:
- Programmable infusion rates
- Patient-controlled analgesia (PCEA) capability
- Bolus options for breakthrough pain
Securement Devices
- Occlusive Dressings: Transparent, sterile adhesive
- Catheter Clamps: Prevent leakage when disconnected
- Anchor Devices: Sutureless catheter securement systems
Selection Guidelines
By Patient Population
| Patient Type | Needle Size | Catheter Type | Special Considerations |
|---|---|---|---|
| Adult | 16G-18G Tuohy | 19G standard | Consider wire-reinforced for long-term use |
| Obstetric | 17G-18G Tuohy | 19G soft tip | Multiple side holes for better spread |
| Pediatric | 19G-20G Tuohy | 22G-24G | |
| Thoracic | 18G Hustead | 19G flexible |
By Clinical Application
- Labor Analgesia: 19G catheter with multiple side holes
- Postoperative Pain: Wire-reinforced catheter for extended use
- Chronic Pain: Specialized catheters for tunneling
- CSE Technique: Needle-through-needle system
Next Steps
Apply this knowledge with our Step-by-Step Insertion Guide.
Understand the broader context of Management and Prevention of Complications.
Page 3 of 4
Managing Epidural Anesthesia: Complication Prevention
Effective management of epidural anesthesia requires vigilance and prompt recognition of complications. This guide covers essential management strategies for anesthesia residents, including proper catheter removal techniques.
Intraoperative Management
- Hemodynamic Monitoring:
- Continuous blood pressure monitoring (every 2-3 min initially)
- Heart rate and rhythm monitoring
- Fluid status assessment
- Sensory Level Assessment:
- Pinprick testing every 5-10 minutes
- Cold sensation testing (alcohol swab)
- Document dermatomal levels bilaterally
- Motor Blockade Assessment:
- Bromage scale:
- Grade 1: Free movement of legs
- Grade 2: Able to flex knees only
- Grade 3: Unable to flex knees, able to move feet only
- Grade 4: Unable to move legs or feet
- Bromage scale:
- Dosing Strategies:
- Bolus dosing: 3-5 mL increments
- Continuous infusion: 5-15 mL/hr
- Patient-controlled epidural analgesia (PCEA): 2-5 mL bolus, 10-15 min lockout
Postoperative Management
- Pain Assessment:
- Regular pain scores (0-10 scale)
- Assess breakthrough pain
- Evaluate sensory/motor function
- Catheter Care:
- Daily inspection of insertion site
- Monitor for signs of infection
- Check catheter position and securement
- Adjuvant Medications:
- Opioids (fentanyl, hydromorphone): Enhance analgesia
- Clonidine: Prolongs duration, reduces opioid requirements
- Epinephrine: Improves quality, decreases systemic absorption
Catheter Removal
Proper catheter removal is as critical as insertion to prevent complications. Follow these guidelines for safe removal.
Timing of Removal
- General Principles:
- Remove when no longer needed (typically 24-72 hours postoperatively)
- Consider earlier removal if signs of infection or complications
- For labor epidurals: Remove after delivery or when analgesia is no longer required
- For chronic pain: May remain for weeks with proper care and tunneling
- Indications for Early Removal:
- Suspected infection (fever, erythema, purulence at site)
- Signs of neurological compromise
- Catheter malfunction or dislodgement
- Patient request or change in care plan
Anticoagulation Precautions
Timing of catheter removal relative to anticoagulant therapy is critical to prevent spinal hematoma:
- General Rule: Remove catheters when coagulation is normal
- Specific Guidelines (ASRA Recommendations):
- Warfarin: Remove when INR ≤ 1.5
- LMWH (Prophylactic): Wait at least 12 hours after last dose
- LMWH (Therapeutic): Wait at least 24 hours after last dose
- Fondaparinux: Wait at least 42-48 hours after last dose
- Direct Oral Anticoagulants (DOACs):
- Dabigatran: Wait 24-48 hours after last dose (depending on renal function)
- Rivaroxaban, Apixaban, Edoxaban: Wait 24-48 hours after last dose
- Antiplatelet Agents:
- Aspirin/NSAIDs: No delay needed
- Clopidogrel: Wait 7 days after last dose
- Prasugrel: Wait 7-10 days after last dose
- Ticagrelor: Wait 5-7 days after last dose
- Post-Removal Anticoagulation:
- Delay next anticoagulant dose for at least 2 hours after removal
- For therapeutic anticoagulation: Wait 4-6 hours after removal
Removal Procedure
- Preparation:
- Verify coagulation status if on anticoagulants
- Gather equipment: sterile gloves, gauze, transparent dressing
- Position patient comfortably (lateral or sitting)
- Explain procedure to patient
- Removal Steps:
- Remove any tape or securement devices
- Clean insertion site with chlorhexidine or alcohol
- Don sterile gloves
- Grasp catheter at skin entry point with non-dominant hand
- With dominant hand, slowly withdraw catheter in a smooth, continuous motion
- Inspect catheter tip for integrity (should be intact)
- Apply gentle pressure with gauze for 2-3 minutes
- Apply sterile occlusive dressing
- Difficult Removal:
- If resistance is met, do not force removal
- Reposition patient (try different positions)
- Apply gentle traction over several minutes
- If still unsuccessful, consider imaging (X-ray) to check for kinking or knotting
- Surgical consultation for rare cases of entrapped catheter
Post-Removal Assessment
After removal, perform the following checks:
- Catheter Inspection:
- Verify tip is intact (no fragments left behind)
- Note any unusual markings or discoloration
- Insertion Site:
- Check for bleeding or hematoma formation
- Inspect for signs of infection (redness, swelling, discharge)
- Apply pressure if bleeding occurs
- Neurological Assessment:
- Assess motor function in lower extremities
- Check sensory function (pinprick, light touch)
- Evaluate for new-onset back pain or radicular symptoms
- Document baseline neurological status
- Patient Instructions:
- Keep dressing dry and intact for 24 hours
- Report fever, severe back pain, or neurological changes immediately
- Avoid heavy lifting for 24 hours
- Follow up if any concerns arise
Documentation
Document the following in the medical record:
- Date and time of removal
- Reason for removal
- Catheter condition (intact, damaged)
- Coagulation status at time of removal
- Any difficulties encountered during removal
- Post-removal neurological assessment
- Patient tolerance of the procedure
- Instructions given to patient
Complications: Recognition and Management
Common Complications
- Hypotension (Incidence: 5-15%)
- Prevention:
- Fluid preloading (500-1000 mL crystalloid)
- Incremental dosing
- Left uterine displacement in pregnancy
- Treatment:
- Fluid bolus (250-500 mL)
- Ephedrine 5-10 mg IV (first line in obstetrics)
- Phenylephrine 50-100 mcg IV (first line in cardiac patients)
- Prevention:
- Dural Puncture ("Wet Tap") (Incidence: 0.5-3%)
- Prevention:
- Use saline for LOR (more reliable)
- Ultrasound guidance for difficult anatomy
- Paramedian approach in challenging cases
- Management:
- Recognize immediately (free-flowing CSF)
- Options:
- Resite at different level
- Convert to spinal anesthetic
- Place catheter intrathecally (intentional spinal)
- Prophylactic blood patch if high risk
- Prevention:
- Inadequate Block (Incidence: 5-10%)
- Causes:
- Catheter malposition (lateral, intravascular, subdural)
- Anatomical variations
- Insufficient dose/concentration
- Management:
- Reposition patient
- Administer supplemental bolus
- Consider catheter replacement
- Rescue with systemic analgesics
- Causes:
Serious Complications
- Epidural Hematoma (Incidence: <0.01%)
- Risk Factors:
- Coagulopathy
- Difficult insertion
- Anticoagulated patients
- Improper timing of catheter removal relative to anticoagulation
- Recognition:
- Severe back pain
- Progressive neurological deficits
- Bowel/bladder dysfunction
- Management:
- Emergency MRI
- Neurosurgical consultation
- Decompression within 8 hours
- Risk Factors:
- Epidural Abscess (Incidence: <0.01%)
- Prevention:
- Strict aseptic technique
- Limit duration of catheterization
- Avoid in immunocompromised patients
- Recognition:
- Fever, back pain, leukocytosis
- Neurological symptoms
- Erythema at insertion site
- Management:
- Blood cultures, CRP, ESR
- MRI with contrast
- IV antibiotics ± surgical drainage
- Prevention:
- Total Spinal Anesthesia (Incidence: <0.1%)
- Causes:
- Unrecognized dural puncture
- Large epidural dose
- Catheter migration into subarachnoid space
- Recognition:
- Rapid ascending sensory level
- Hypotension, bradycardia
- Respiratory depression/apnea
- Management:
- ABCs: Intubate if respiratory compromise
- Aggressive hemodynamic support
- Stop surgery if severe
- Causes:
Quality Improvement
- Regular audit of complication rates
- Standardized documentation templates
- Peer review of difficult cases
- Simulation training for emergency scenarios
Further Learning
Review equipment details in our Epidural Needles and Equipment guide.
Perfect your technique with our Step-by-Step Insertion resource.