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K. Mohan Epidural Anesthesia Presentation
- 1. EPIDURAL ANESTHESIA PREPARED BY: K. MOHAN B.SC OTT ( FINAL YEAR ) AHS, MGMCRI
- 2. INTRODUCTION • All surgerieswhich can be performed under spinal anaesthesia can be performed under epidural block. • In addition, epidural can be utilized for upper abdominal, thoracic ( under thoracic epidural ) and even neck surgeries ( under cervical epidural ). • However in clinical practice epidural is mainly used for postoperative pain management and painless labor. • Epidural is also used in chronic pain management.
- 3. EPIDURAL NEEDLES • Themost commonly used needle for epidural is Tuohy needle . • It is blunt bevel with curve of 15 to 30 degree at tip. • This curved tip is called as Huber tip. • Other needles which can be used for epidural are Weiss ( it is winged ) and Crawford ( straight blunt bevel with no curved )
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- 5. INJECTIONS SITE • Unlikespinal anaesthesia, produces a segmental block that spreads both caudally and cranially • Injections site is arguably the most important determinant of the spread of an epidural block • The injection site should be in the middle of the range of dermatomes that needs to be anesthetized and closet to the main nerve roots involved • Caudal epidural blocks are largely restricted to sacral and low lumbar detmatomes
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- 7. CONTINUES • Thoracic levelscan be reached by the caudal approach only if large volumes ( 30cc ) are given and then the block is patchy at best because of the distance that the anesthetic has to travel • Lumbar local anesthetic injection of 10cc tend to spread cauded to include all the sacral dermatomes • Lumbar injections of 20cc volumes produce much better quality sacral blocks and can also extend cranially to include the midthoracic levels
- 8. CONTINUES • Thoracic injectionstend to produce a symmetric segmental band of anaesthesia with minimal lumbar spread • It is generally not feasible to produce surgical anesthesia in the low lumbar or sacral nerve distribution when using thoracic injections sites • Thoracic injections sites are ideally suited for procedures of the chest and upper abdomen or for relief of post- op thoracotomy pain with a catheter being placed for continuous infusions
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- 10. POSITION • Lateral positionmay be preferred position to optimize spread • Sitting position has anatomical advantages • Studies have shown small to no differences in spread of block when comparing the two position
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- 12. TECHNIQUE • Like spinalit can be given in sitting and lateral position. Usually epidural space is encountered at 4-5 cm from skin and has negative pressure in 80% individuals • Most commonly used method to locate epidural space is by loss of resistance technique. once the needle pierces the ligamentum flavum there is sudden loss of resistance and syringe filled with air or saline will be felt literally sucked in epidural sace. • Another popular technique of past, hanging drop technique ( Gutierrez’s sign ){ if a drop of saline is placed on the hub of needle it will be sucked in due to negative pressure once the needle is in epidural space } is hardly used in current day practice.
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- 14. CONTINUE • Once theneedle is confirmed in epidural space, a test dose of 2-3 ml of hyperbaric lignocaine with adrenaline ( except for obstetric patient where epinephrine should not be used ) is given and if in 5 minutes there is no evidence of either spinal block ( inability to move foot ) or intravascular injection ( tachycardia by adrenaline ), further doses can be given. • Epidural catheter is passed through the needle. 3-4 cm of catheter should be in epidural space. A microfilter is attached to catheter to prevent contamination. • Onset of effect takes place in 15-20 minutes.
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- 16. PREPARATION • Place patientin optimal position • Prepare skin over a wide area with povidine iodine • Fenestrated sterile drape • Find the interspace along the midline
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- 18. CONFIRMATION • Sudden disappearenceof resistence • Sudden ease of injection of air • Hanging drop sign • Capillary tube method of odom ( movement of air bubble in a capillary tube attached to hub )
- 19. CATHETER • Made ofpolyurethane or polymide • Polymide – stiffer, threading easier • Chance of dural or venous puncture • Closed tip • Multiple side hole • Spring wire reinforced polymer coated
- 20. CONTINUES • Threading difficult– advance and try again • If c/o pain, remove and reintroduce by changing angle of needle or rotated on either side an try again • LA prior to insertion – may open up false spaces faulty catheter insertion
- 21. SITE OF ACTIONDRUGS • Anterior and posterior nerve roots ( main site of action ) • Mixed spinal nerves • Drug diffuses through dura and arachnoid and inhibits descending pathways in spinal cord
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- 23. DRUGS USED FOREPIDURALANESTHESIA • LOCAL ANESTHETICS : Usually 2-3 ml of local anaesthetic is required for blocking 1 segment ; therefore normaly 15 to 20 ml of drug is required. Lignocaine : 1-2 % concentration is used Bupivacaine 0.625-0.5 %, ropivacaine 0.1 – 1.0 and Levobupivacaine 0.125 – 0.75 % depending whether used for sensory or motor block. Ropivacaine because of if high safety profile is most preferred .
- 24. CONTINUES • OPIOIDS : MOPHINE: 4-6 mg ( diluted in 10 ml saline ). Onset within 30 minutes. Effect lasts for 12-16 hours. Depodur is an extended –release liposomal formulation of morphine which can provide analgesia for 48 hours. FENTANYL : 100mcg ( diluted in 10 ml saline ). Onset within 10 minutes. Effect lasts for 2-3 hours.
- 25. ADVANTAGES OF EPIDURALOPIOIDS OVER LOCAL ANESTHETICS • Only sensory block is produced while with local anaesthetics there are chances of motor blockade if high concentration is used. • The effects of single dose ( especially morphine ) lasts long ( 12-16 hrs ) obviating the need for frequent injections • No sympathetic block.
- 26. DISADVANTAGES OF EPIDURALOPIOIDS OVER LOCAL ANESTHETICS • Respiratory depression • Urinary retention • Pruritus • Nausea and vomiting • Sedation
- 27. CONTINUE • ADJUVANT DRUGS: Adjuvant drugs like clonidine, dexmedetomidine, neostigmine and ketamine has been tried to enhance the onset, augment analgesic effect and improve quality of block but with variable results. • LIPOSOMAL BUPIVACAINE : Liposomal bupivacaine which can produce longer lasting analgesia is currently under investigation.
- 28. FACTORS AFFECTING THESPREAD ( LEVEL ) OF BLOCK • Volume of the drug : It is the most important factor • Age : Old requiring less dose because volume of epidural space is less. • Gravity : Dose not affect level too much as in case of spinal • Level of injection • Length of vertebral column : Taller individuals require higher dose • Concentration of local anesthetic : High the concentration, higher is the spread.
- 29. ADVANTAGES OF EPIDURALOVER SPINAL • Less hypotension : As the onset of action of epidural is slow body gets sufficient time to compensate for hypotension making epidural a better choice than spinal for cardiac compromised patients. • No postspinal headache however headache can occur if dura is punctured accidentally. • By giving top up doses through catheter level of block and duration of anaesthesia can be changed.
- 30. DISADVANTAGES OF OVERSPINAL • Inadequate ( patchy ) block/block failure rate is high • Higher chances of total spinal • Accidental dural puncture • More chance of epidural hematoma and intravascular injection • Higher chance of infections complications • Higher incidence of local anaesthetic toxicity • Higher incidence of neuropathies • Intraocular hemorrhage
- 31. CONTRAINDICATIONS • ABSOLUTE : Infection Patientrefusal Coagulopathy or other bleeding diathesis Severe hypovolemia Increased intracranial tension Severe aortic stenosis Severe mitral stenosis
- 32. CONTINUES • RELATIVE : Sepsis Preexistingneurological deficits Demyelinating lesions Stenotic valvular heart lesions Severe spinal deformities Prior back surgery at the site Inability to communicate