Technique of SPINAL ANESTHESIA indication and contraindication Guided by: Dr. Shubhada Deshmukh(M.D.) Presented by: Dr.Anurag Giri

Spinal anesthesia is also called as spinal block or subarachnoid block (sab). SAB is a regional anesthesia involving injection of a local anesthesia into the subarachnoid space which extends from the foramen magnum to S2 in adults and S3 in children. Injection of LA below LI in adults and L3 in children helps to avoid direct trauma to the spinal cord , (anesthetic agents acts on the spinal nerve and not on the substance of the cord) Spinal Anesthesia

Corning in 1885 , accidently administered cocaine intrathecally.Quincke in 1891 , made use of spinal puncture in diagnosis.August bier of Germany in 1898 , introduced the technique of spinal anesthesia.Pitkin popularized the method of introducing agent's intrathecally.

History

Informed consent.Physical examination , history (past surgical ).Laboratory test.Premedication Diazepam 0.1-0.2 mg/kg Po midazolam 1-3 mg I/MPreoperative evaluation and preparation

Used both alone and in combination with either GA or sedation.Lower limb orthopedic surgery on the pelvis, femur , tibia and ankle.Total hip replacement.Total knee replacement.Lower limb vascular surgery.4) INDICATION OF SPINAL ANESTHESIA

Hernia (Ingunial or epigastric).Haemorrhoidectomy , fistula , fissure.Nephrectomy and cystectomy in combination with GA.Transurethral resection of the prostate and transurethral resection of the bladder tumors.Abdominal and vaginal hysterectomiesLaproscopic assisted vaginal hysterectomies(LAVH) combined with GA.Caesarean sections.

ABSOLUTEPatient refusalInfection at the site of injectionCoagulopathy or other bleeding diathesisSevere hypovolemiaIncreased intracranial pressureSevere aortic stenosis Severe mitral stenosis Post traumatic vertibral injuries , myocardial infract. Contraindication

RELATIVE

SepsisUn co-operative patientPre existing neurological deficitStenotic valvular heart diseaseSevere spinal deformitySpinal congenital anomaliesHypo tensionHyper tensionSevere anaemiaShock(haemorragic,septic)Brain tumor

4 PsPreparationPositionProjectionPunctureRECOMMENDATIONS FOR SAFE SPINAL TECHNIQUES

Scrub hands according to aseptic surgical techniqueUse sterile glows Avoid contaminating blocking solutions with solutions used to prepare the skin.Use aseptic technique when opening tray.Clean the skin prior to needle puncture.Touch only sterile articles once gloved.Use introducer prior to injection of small guage spinal needle. Avoid repeated traumatic punctures.Use approved local anaesthetic agents in standard concentration

Clean the skin surface twice with betadine and twice with spirit using window technique with sterile gauzeCLEANING AND DRAPPING

NEEDLESThe standard spinal needle-Three parts Hub , cannula, styletPoints of cannulae are beveled and have sharp edge Cannulae made of stainless steel should be stiff, flexible and resistant to breakage.Sizes- 16 G to 30 GLength- 3.5 to 4 inchesNEEDLES CLASSIFIED 1. Standard bevelled with cutting edges-Quincke ,Babcock or Pitkin2. Pencil point needle with conical point with no cutting edges- Sprotte, Greene .

SPINAL ANASTHESIA TECHNIQUE

Large IV cannula IV fluids immediately before the spinal The volume of fluid given will vary with age and extent of blockIdeally 10ml/kg Crystalloids like Ringer lactate , 0.9% normal saline are usedNow co-loading.

INTRAVENOUS PRELOADING

L.P. is most easily performed when there is maximum flexion of lumbar spine .By this ligaments get stretched and space is open

POSITIONS

TWO ASPECTS1. Spinal canal should be on horizontal plane2. Operator should fix his or her gaze on the horizontal plane.POSITIONINGFlexed lateral position- back should be parallel to the edge of the table, knees are flexed on the abdomen, neck flexed. Jack knife positionLATERAL POSITION

The anatomic midline is often easier to aproach when the patient is in sitting position .Patient sit with their elbows resting on their thighs or bedside table or they can hug a pillow. Flexon of spine miximizes the target area between adjacent spinous processes and brings the spine closer to skin surfaceSITTING POSITION

This position is used for anorectal procedures utilising a hypobaric anasthetic solutionProne position

Vertebral Spinous processes and the iliac crestsSpinous processes clearly define the midlineLine drawn between the iliac crests- intercristine or Tuffiers line crosses the 4th lumber vertebrae.

LANDMARK

The depression between the spinous process of the vertibra above and below the level to be used is palpated.This will be the middle entry site.The spinous process course downwards from the spine towards the skin so the needle will be directed cephaladThe subcutaneous tissue gives feeling of little resistance to the needle,after that needle will enter the supra spinous and infra spinous ligaments felt as an increase in tissue density .As the needle meets the ligamentum flavam an increase in resistance is encountered and on piercing it, loss of resistance can be felt .The needle is advanced through the epidural space and penetrates the dura (2nd resistance) and subarachnoid membrane as signaled by free-flowing CSF.MIDLINE APPROACH

USE OF AN INTRODUCER Concept of Introducer was that of Lincoln Size.Modifications- Pitkin and by Lundy.

Purpose- Spinal needle can be inserted to the depth of the interspace without touching the skin, subcutaneous tissues and ligaments.Grasping and stabilising

OBJECTIVES OF INTRODUCER Infection ContaminationFacilitate introduction of Spinal needle.Minimize introduction of skin and tissue fragments Avoid development of SAB epitheliomas and epidural tumors.

The paramedian approach may be selected if SAB is difficult(severe arthritis or prior LS spine surgery) The skin wheal for the paramedian approach is raised 2cm lateral to the inferior aspect of the superior spinous process of the desired level.The needle is directed and advanced at a 10-25degree angle towards the midlinepARAMEDIAn/ lateral aproach

This is a very useful method in cases of spine fusion, arthritic spine, opisthotones , skin infection in the lumbar region , or in other conditions in which the usual approach is difficult or impossible.Largest interspase L5-S1.A skin wheal is made 1cm medially and 1cm below the lowest prominence of the posterior-superior spine. A 12-cm , needle is directed upward , medially and forward at an angle of about 50degree , approximating forward at an angle that the dorsal aspect of the sacrum makes with the skin. The needle then is advanced so that its point enters the lumbosacral space between the sacrum and the last lumbar vertebra. As the space is entered , there usually an immediate flow of CSF , although gentle aspiration may be necessary.Taylor technique

The spinal needle feels as if it is in the right position but no CSF appears. Wait at least 30 seconds, then try rotating the needle 90 degrees and wait again. If there is still no CSF, attach an empty 2ml syringe and inject 0.5-1ml of air to ensure the needle is not blocked then use the syringe to aspirate whilst slowly withdrawing the spinal needle. Stop as soon as CSF appears in the syringe.

Blood flows from the spinal needle. Wait a short time. If the blood becomes pinkish and finally clear, all is well. If blood only continues to drip, then it is likely that the needle tip is in an epidural vein and it should be advanced a little further to pierce the dura.

The patient complains of sharp, stabbing leg pain. The needle has hit a nerve root because it has deviated laterally. Withdraw the needle and redirect it more medially away from the affected side.Practical Problems

The patient complains of pain during needle insertion. This suggests that the spinal needle is passing through the muscle on either side of the ligaments. Redirect your needle away from the side of the pain to get back into the midline or inject some local anaesthetic.

Wherever the needle is directed, it seems to strike bone. Make sure the patient is still properly positioned with as much lumbar flexion as possible and that the needle is still in the mid-line. It might be better to attempt a paramedian approach to the dura.

PRINCIPLES IN ADMINISTRATING ANAESTHETIC SOLUTIONSMain aim of anaesthetists is to secure anaesthesia of Sufficient duration Sufficient Height.STOUTS PRINCIPLES FOR SPREAD OF SOLUTIONSHeight of anaesthesia isDirectly proportional to concentration of the drugInversely proportional to rapidity of fixationDirectly to speed of injection Directly proportional to the volume of fluid.Inversely proportional to spinal fluid pressure.Directly proportional to specific gravity for hyper baric solution.With isobaric or hypobaric solutions, extent depends on position of patient.

FACTORS POSTULATED TO BE RELATED TO SPINAL ANAESTHETIC BLOCK HEIGHT PATIENT CHARACTERISTICSAge, Height, Weight, Intra abdominal pressure, position, anatomic configuration of spinal column.TECHNIQUE OF INJECTIONSite of injection, direction of injection, rate of injection.CHARACTERISTICS OF SPINAL FLUIDVolume, Pressure, density.CHARACTERISTICS OF ANAESTHETIC SOLUTIONSDensity, Amount, Concentration, temperature, volume.

This is the technique of stirring up to increase turbulence , mixing of injected solutions and increasing the distribution in the subarachnoid space. The technique first was described by Bier and consists of the injection of the anesthetic solution into the subarachnoid space, immediate withdrawal of a portion of the solution and reinjection. This may be repeated. The to-and-fro movement agitates the injectate in the spinal fluid, and the currents mix the agent more completely and carry the agent more extensively and to higher levels. Caution must be observed and each operator must learn the results of his barbotagebarbotage

PATIENT FACTORSAGE Spinal space become smaller with age - distribution greater.OBESITY Increase intra-abdominal pressure increase pressure in epidural space. Decrease subarachnoid spacePREGNANCY Increase intra-abdominal pressure Increase volume of epidural venous plexus - Small subarachnoid spaces.

INTRAABDOMINAL PRESSUREChanges resulting from direct pressure of increased intra-abdominal pressure on epidural and subarachnoid spaces.Collateral flow through epidural venous plexus expand- SA space smallSPINAL CURVATUREAbnormal curvature have an effect on technical aspects Changes the contour of Subarachnioid spaceRATE OF INJECTION Slow injections - low levelsRapid injections - high level

CHARACHTERISTICS OF ANAESTHETIC SOLUTIONSAMOUNT OF DRUGIncrease amount- increase DurationEFFECT OF TEMPERATUREDecrease Temperature- increase Baricity

CHARACHTERISTICS OF ANAESTHETIC SOLUTIONS

DENSITY / SPECIFIC GRAVITY AND BARICITYDensity of any solution is the weight in grams of 1 ml of the solution at a standard temperature. Density varies inversely with temperature.Specific gravity is the density of a solutions compared in a ratio with the density of water.Baricity is a ratio comparing the density of one solution to another.Density of normal human. CSF at 370C is 1.0001 to 1.0005Specific gravity of spinal fluid 1.003 to 1.008ISOBARIC SOLUTIONS Densities between 0.9998 and 1.0008Solutions are mixed with physiological saline Solutions with out added glucose Bupivacaine, ropivacaine, levobupivacaine Spread not influenced by position

HYPOBARIC SOLUTIONSBaricity less than 0.9998 at 370CPrepared by diluting with distilled water HYPERBARIC SOLUTIONSSolutions at 370c with baricity greater than 1.0008Made by addition of 5-9.5% dextrose.

Problems with the BlockNo apparent sab at all. If after 10 minutes the patient still has full power in the legs and normal sensation, then the block has failed probably because the injection was not intrathecal. Try again.

The sab is one-sided or is not high enough on one side. lie the patient on the side that is inadequately blocked for a few minutes and adjust the table so that the patient is slightly "head down".

sab not high enough. tilt the patient head down while they are supine (lying on the back), so that the solution can run up the lumbar curvature. Flatten the lumbar curvature by raising the patient's knees.

Block too high. The patient may complain of difficulty in breathing or of tingling in the arms or hands. Do not tilt the table "head up".

CLASSIFIED INTO:Single injection techniqueHyperbaricIsobaricHypobaricContinuous injection methodIntermittant or fractionalDifferential blockContinuous dripSegmental methodSPINAL ANASTHESIA TECHNIQUE

1. Procaine-Anaesthetic solution used is procaine mixed each 50mg of procaine crystal with each 1ml of CSFDosage-For lower extremities and perinium 50-100mg For lower abdomen 100-150 mg For upper abdomen 150-200mg2. Lidocaine dextrose-Premixed solution is available lidocaine 5% in 5% dextrose or lidocaine 5% in 7.5% dextrose to a volume of 2.5ml or 50mg/ml of lidocaine.Dosage-For lower extremities and periniom 40-60mg For lower abdominal 75mg . For upper abdominal 100-150mg HYPerBARIC

3. Bupivacaine dextrose- An optimal concerntration of bupivacaine is 0.5% in 5% dextrose Dosage-For lower extrimities and perinium 1.5 -2.5ml(7.5 -12.5mg of bupivacaine) 1.5ml will provide level of T10. 2ml will provide level of T8 For lower abdomen 2.5ml-3.0ml(12.5-17.5mg)3.0ml provides anesthesia to T6 level For upper abdomen (high spinal) 3.5 to 4.5 ml (17.5-25mg) 4ml will provide anasthesia usually upto T4 level4. Teracaine dextrose- Rarely used in practice5.Dibucaine dextrose-Rarely used in practice

1.Dibucaine-Anasthetic solution 1:1000 or 0.1% dibucaine solution is used.To make this solution minimum 1vol. of 0.5% dibucaine in a buffered phosphate sodium chloride solution with 4vol. Of CSF.For lower extrimities and perinium 0.5 to 1mlFor lower abdomen 1to 1.5 mlFor upper abdomen 1.5 to 2ml2. Bupivacaine isobaric-0.5% bupivacaine solution in isotonic saline.For lower extrimities and perinium 1-2mlof bupivacaine achieved level upto T10 -T12For lower abdomen 2.5 -3.0ml level upto T8 T6.For upper abdomen 3.5-5.0ml level upto T6-T4.ISOBARIC

1.Tetracaine in distilled water 0.1% tetracaine hydrochloride solution is commonly used.Hypobaric tetracaine (naphanoid) crystalline powder in a sterile ampoule containing 20mg of tetracaine is dissolved in sterile distilled water for injectionDosage-For lower extremities and perinium 5-10mg For lower abdomen 10-15mg For upper abdomen 15-20mg2. Dibucaine hypobaric-Anasthetic sloution dibucaine 1;1500 in 0.5% saline each 1.5ml contains 1mg of dibucaine.Dosage-For lower extremities and perinium 5-10ml For lower abdomen 10-15ml For upper abdomen 15-20 mlhypobaric

inserting a catheter into the subarachnoid space increases the utility of spinal anesthesia by permitting continuous or repeated drug delivery in order to expand the level or duration of spinal block dural puncture is done with an epidural needle . After the subarachnoid placement of the needle and ascertaining free flow of csf ,the catheter is threaded 2-3 cm in to the subarachnoid space .the catheter should never be pulled back in to the needle shaft because of the risk of shearing the catheter off into the subarachnonid spaceIf the catheter needs to be removed both needle and catheter should be removed as a unit . 18 G epidural needle &20 G epidural catheter are used Stimulation of nerve root by the catheter tip is painful and catheter can enter subarachnoid vessel

CONTINUOUS INJECTION METHOD

Sensation of temperature- Ice, AlcoholSensation of Pin-prick Blunt tipped / ForcepMotor power Bromage scale 0 No motor block 1 Can flex knee, move foot, but cannot raise leg 2 Can move foot only 3 Cannot move foot or kneeTesting of Effect

Sedation only is recommended in infants older than 6-8 weeks.Conceptual age of 48weeks or more to permit quite and safe for spinal tap.Generally the preterm neonate or infant of a conceptual age less than 48 weeks will not need sedation but clinical judgement will determine the need.Ketamine 1-2mg/kg with atropine15-20 micro gram /kgMidazolam 50-100 micro gram/kg.

SPINAL ANASTHESIA IN INFANTS AND CHILDREN

The lateral position is preferred with the table tilted and the head up at 100degree to faster filling of the lumber subarachnoid space.The sitting position may also be used.The puncture at L3 L4 vertibra interspace for children of 1-18yrs and L5 for infants.The spinal needle directed perpendicular to plane of the back.A standard 24-26G needle is used.Dosage-Minimum vol. of 0.2ml is necessary in the preterm or newborn infantInfant under 3000gm requires the largest doses because larger vol. of CSF and absorption doses upto 0.6mg/kg may be given to infant of 2-3kg of weightFor infant over 3kg the dose is stablised at 0.35 mg/kg upto 1yr of age.POSITION

After administration of spinal anasthesia iv line may be easily started in a foot vein because of venous dilatation. Monitoring of pulse ,BP and Oxygen saturation is an additional standard.monitoring

THANKS ALL

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