1. Local & regional anesthesia  Local anesthetic agent act by reducing membrane permeability to sodium  Act on small unmyelinated C fiber before large A fibers  Reduce pain & temperature sensation before touch & power What drugs are used ?  Bupivacaine (Marcaine) is a common longer – actiner anesthetic, widely used for epidurals, spinal & other blocks  Lidocaine also called (Xylocaine, lignocaine) is the most common of the short acting local anesthetics, & is used in many procedures  Mepivacaine is similar to lidocaine  Ropivacaine is a new longer acting agent which appears to be safer than Bupivacaine  Tetracaine is used mainly for spinal  Cocaine is still used as a local anesthetic in special cases  Other drugs may be added to the local anesthetic Adjuncts  Opoid  Epinephrine  Clonidine  others

2. Lignocaine  Lignocaine is a weak base (PKa=7.8)  At physiological PH mainly ionised  Has a duration of action of about 1 hour  With addition of adrenaline duration of action can be increased to 2 hours  Main toxicity is on CNS & CVS  Plain lignocaine should be used for local anesthesia in digits & appendages  Adrenaline containing solutions can cause tissue ischemia Bupivacaine Bupivacaine  Effective  Medium duration  Tachyphylaxis rare  High plasma protein bound  Selective cardiotoxicity

3. Regional anesthesia  A general anesthesia is not always necessary or advisable.  Depending on the type of operation, the anesthetist can use techniques to completely numb soecific parts of the body.  Regional anesthesia is used increasingly frequently to avoid the possible side- effect of GA.  It can also be useful in people who are too frail to undergo a general anesthesia.  With a regional anesthesia, a small amount of an anesthetic drug is injected near to the nerves that supply a part of the body.  The anesthetic temporarily prevents the nerve from sending any messages to the brain – where pain is registered – so the part of the body is completely insensitive to pain. Why choose a local or regional anesthesia  Avoids some of the risks & unpleasantness, such as nausea & vomiting, which sometimes occurs with GA.  providing pain relief for several hours after the operation.  Reduce blood loss.  Some patients feel more (in control) when they are awake during surgery.

4. How it is used?  Used in addition to a general anesthetic.  Provide pain relief after surgery.  Nerve block are also used in the diagnosis & treatment of some painful conditions.  Prevent pain during surgery.  Provide pain relief during labour. Reasons to avoid a local or regional anesthesia  Some surgeons are not used to operating on awake patients & may be too rough or impatient for successful regional anestheia.  Some anesthetists do not have the skills required to perform the necessary procedures.  Some patient cannot cope with idea of being awake during surgery.

5. Blocks for various parts of the body  Local infiltration for cuts & small procedures.  Blocks for eye surgery.  Blocks for hand & arm surgery : local infiltration, blocks of individual fingers, iv regional blocks, axillary blocks.  Spinal & epidural anesthesia.  Caudal anesthesia.  Pain relief in labour. Maximum doses of local anesthetic (average adult) plain solution with adrenaline plain solution with adrenaline Lignocaine 200 mg (20 ml of 1%) 500 mg (50 ml of 1%) Bupivicaine 150 mg (30 ml of 0.5%) 200 mg (40 ml of 0.5%) Prilocaine 400 mg (80 ml of 1.5%) 600 mg (120 ml of 1.5%)

6. Spinal & epidural anesthesia  Spinal anesthesia – local anesthetic or opiad injected into CSF below termination of cord at L1(adult).  Used for operations below the waist or in the pelvic region.  The patient completely numb from the waist down for a couple of hours.  Epidural anesthesia - local anesthetic or opiad injected into fatty epidural space.  An epidural uses a similar technique to spinal anesthesia, with a (catheter) narrow plastic cannula left in position near to the nerves in the back  This means that the anesthetist can give repeated doses of local anesthetics & (painkillers) without further injection.  This makes it useful for longer operations.  An epidural can be used for postoperative pain relief & for labour pain.  Both can produce good anesthesia for up to 2hours  The quality of block is often better with a spinal.  Epidural anesthesia is technically more demanding.

7. Contraindications to central blockade Absolute SSSSepsis BBBBacteremia SSSSkin infection at injection site SSSSever hypovolaemia CCCCoagulopathy TTTTherapeutic anticoagulation IIIIncrease intracranial pressure LLLLack of consent Relative PPPPeripheral neuropathy MMMMini – dose heparin PPPPsychosis Or dementia AAAAspirin or other antiplatelet drugs DDDDemyelating central nervous system disease CCCCertain cardiac lesion - idiopathic hypertrophic subaortic stenosis - aortic stenosis PPPPsychologic or emotional instability UUUUncooperative patient PPPProlong suergery SSSSurgery of uncertain duration SSSSurgical team resistance to awake patient

8. Complications spinal Epidural spinal Epidural  Hypotension Common Less common  LA toxicity Rare Occasional  High blockade Occasional Occasional  Urinary retention Common Less common  Headache 1-5% never unless dural puncture  Local infection Almost never Uncommon  Meningism Uncommon very rare  Epidural haematoma Almost never very rare  Backache common common Common uses for spinal :  Caesarean section  Hernia repair  Hip & knee surgery  Most procedure on the foot or leg

9. IV Regional anesthesia IV Regional anesthesia  Also known as a Bier block  Used on surgery of the upper & lower extremities  Patient must an IV cannula inserted in the operative extrmity  After a pneumatic tourniquet is applied to extremity, Lidocaine is injected through IV  Anesthesia lasts until the tourniquet is deflated at the end of the case  IMPORTANT- to prevent an overdose of lidocaine it is impotant not to deflate the tourniquet quickly at the end of the procedure  The anesthetist will deflate/ inflate tourniquet several times before complete deflation of tourniquet cuff Injection of local anesthetic around a peripheral nerve  Can be used for anesthesia during surgery or for post-op pain relief  Examples : ankle block for foot surgery, supraclavicular block for post-op pain control after shoulder surgery  For operations on a small area of the body  It is possible to simply inject local anesthetic at the site of the operation  This technique is often performed by the surgeon or GP in minor surgery unit