Duration of Epidural Block with Lignocaine
The duration of epidural analgesia with lignocaine (lidocaine) is approximately 60-90 minutes for standard concentrations, though this can be extended with adjuvants or continuous infusion techniques.
Standard Duration Parameters
The baseline duration of epidural lignocaine depends on concentration and adjuvant use:
- Plain lignocaine solutions provide relatively short-duration analgesia, typically requiring repeat dosing or continuous infusion for sustained effect 1
- Lignocaine with epinephrine (adrenaline) extends the duration compared to plain solutions, though specific duration data for epidural use is limited in the provided guidelines 2
- Addition of opioids (such as fentanyl) can prolong analgesic effects when co-administered with lignocaine 1, 2
Concentration and Volume Effects
The intensity and quality of block are affected by concentration:
- 2% lignocaine produces more intense blockade of both large and small-diameter sensory nerve fibers compared to 1% lignocaine, though the duration difference is not explicitly stated 3
- Higher concentrations may provide more reliable surgical anesthesia but do not necessarily translate to proportionally longer duration 3
Clinical Context for Epidural Lignocaine Use
For Labor Analgesia Extension
When extending epidural analgesia for urgent cesarean section, 2% lignocaine with adrenaline and fentanyl achieves surgical readiness (T4 sensory level) in approximately 9.5 minutes (median), with an interquartile range of 7.0-13.3 minutes 2. However, this study focused on onset rather than total duration.
Comparison with Longer-Acting Agents
Lignocaine provides shorter duration compared to:
- Levobupivacaine 0.5% provides longer sensory block duration than lignocaine with adrenaline and fentanyl 2
- Ropivacaine 0.75% also provides extended duration compared to lignocaine formulations 2
Strategies to Extend Duration
Adjuvant Use
- Neostigmine (100-200 μg) co-administered with lignocaine 1% significantly prolongs the duration of analgesia in a dose-independent manner, though the exact duration extension is not quantified in the available evidence 1
- Clonidine (150 μg) combined with lignocaine (40 mg) provides superior analgesia compared to lignocaine alone in chronic pain patients, suggesting synergistic effects 4
Continuous Infusion Techniques
For sustained analgesia beyond the single-shot duration:
- Programmed intermittent epidural bolus (PIEB) regimens using bupivacaine (not lignocaine) demonstrate optimal intervals of approximately 40 minutes for 10 mL boluses 5
- Continuous epidural infusion is the standard approach when prolonged analgesia is required, though specific infusion rates for lignocaine are not detailed in the provided guidelines
Important Clinical Caveats
Toxicity Considerations
When using epidural lignocaine, be aware of cumulative dosing:
- Maximum safe dosing should not exceed 3 mg/kg/h to avoid toxic effects including CNS depression, convulsions, and hypotension 6
- Caution with multiple local anesthetic sources: Do not combine epidural lignocaine with other regional blocks or topical applications within 4 hours to minimize toxicity risk 7
- Plasma concentration monitoring: Therapeutic levels are typically <5 μg/mL, with serious toxicity occurring around 9-10 μg/mL 6
Test Dosing
When verifying epidural catheter placement:
- Test doses should not exceed the equivalent of 10 mg bupivacaine to minimize risk of high or total spinal anesthesia if the catheter is inadvertently intrathecal 6
- For lignocaine specifically, 30-45 mg has been studied for distinguishing intrathecal from epidural placement, though motor block assessment at 5 minutes is more reliable than earlier subjective symptoms 6