Spinal and Epidural Anesthesia

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Information about Spinal and Epidural Anesthesia
Health & Medicine

Published on March 1, 2014

Author: praveensurgeon

Source: slideshare.net


Epidural and Spinal Anaesthesia are safer and cheaper than general anaesthesia. Epidural anaesthesia is even better than spinal anaesthesia. Post-operative pain management can be done effectively with Epidural by placing a catheter in epidural space and by injecting medicine to relieve pain.

Spinal Column Anatomy  Vertebra      Vertebral Body Pedicles Anterior (2) & Laminae Posterior (2) Transverse Process – Junction of the Pedicles and Laminae Spinous Processes – Joining of the Laminae Intervertebral Disks

 Avoids Hazards of General Anesthesia  Patient is Alert earlier postoperative  Lower incidence of Nausea/Vomiting  Better Pain Control/Less Narcotics

 Indications  Best reserved for operations below the level of the umbilicus   R/LIH, GYN, Peroneal, Anal, LE’s C-sections   Preferable to Epidural & GA  Risk/Benefit Ratio Contraindications      Refusal Infection Severe Neurological Disease Hypovolemia Coagulopathy  LMWH use?

 Overall   incidence of Spinal Hematoma Estimated < 1/220,000 – SAB Estimated < 1/150,000 - CLE  Benefit/Risk Ratio  Recommendations


A single injection of a local anesthetic solution into the subarachnoid space usually at the lumbar level  Intrathecal Narcotics  Commonly at L3-L4  Largest Interspace  L5-S1

 Small needles PDPH  Large needles improve tactile sensations  Pencil-point needles PDPH risk  Further reduction with addition of ITN  Side injection needles with large holes CSF but careful to have entire hole subarachnoid

 Baricity of anesthetic solution  Position of the patient   During injection Immediately after injection  Drug   Dosage (mg) Concentration times volume Addition of Opioids  Site of Injection

 Patient  Age Elderly patients > 80 yrs  Patient Height  Intra-abdominal Pressure  Pregnancy & Obesity  Drug Volume

 Added Vasoconstrictor  Rate of Injection  Except for Hypobaric  Gender  Females < Males  Pregnant versus Non-pregnant  Weight  Increased Weight  Lesser concentration needed?

 Sympathetic Block dermatomes higher than the sensory block 2 T5 Sensory Motor  2-6  Motor Sympathetic Block dermatomes lower than sensory block

 Isobaric  – Stays where you put it LA has the same density or specific gravity as CSF (1.0031.008) – Normal Saline  Hypobaric  – “Floats” up – Lighter than CSF LA has a density or specific gravity that is less than CSF (<1.003) – Sterile Water  Hyperbaric – Settles to Dependent aspect of the subarachnoid space – Heavier than CSF  LA has a density or specific gravity that is greater than CSF (>1.008) - Dextrose

 Sitting  With Legs hanging over side of bed     Have the patient hug a pillow Put Feet up on a Stool (no wheels) Assistant MUST keep the patient from Swaying Curve her back like a “C”, Halloween Cat, Shrimp, Cannon ball Up in the Bed (quicker but not optimal)  Baricity?   Lateral Decubitus (Left or Right?) Needs to be Parallel to the Edge of the Bed  Legs Flexed up to Abdomen  Forehead Flexed down towards Knees   Jack-knife Position Chosen for ano-rectal surgery  CSF will not drip from hub of needle  Use hypobaric solution   Bupivacaine less run-off than lidocaine

 Identify Suitable Patients  Equipment Required  Single-shot or Catheter Placement   Continuous spinal with epidural catheter Know your Spinal/Epidural Kit  Determine   Insertion Approach Midline Paramedian

 Midline Most commonly used  As needle passes thru the dura mater a “pop” is often appreciated  CSF flows thru once stylet is used   For small gauge needles (26-29 g) this may take 5-10 seconds   May take even longer in dehydrated or elderly patients If no CSF flow, needle can be obstructed by a nerve root (rotate 90 degrees)

  After identifying the proper interspace palpate the spinous process Insert needle 1 cm lateral and 1 cm inferior to this point and direct needle towards interspace   May need to walk medially off of transverse process Ligamentum flavum is usually the first resistance indentified  Traditional Bypasses supraspinous and intraspinous ligaments Taylor (L5-S1)

 GIVE INTRAVENOUS FLUID BOLUS OF 500 CC PRIOR TO SAB/EPIDURAL DOSE.  If it is not a labor epidural/c-section, give versed, fentanyl and oxygen prior to neuraxial anesthesia.  Local Anesthetics to the skin, deep tissues?  Skin wheal should be performed at vertebral interspace (1-2 ml) and to adjacent sides (.5ml) with 1% Lidocaine

Unable to locate CSF Inability to enter SA space   If bone (os) encountered superficially redirect needle cephalad If bone (os) encountered deep redirect needle caudally Inability to aspirate CSF before injection Ensure that you have CSF in all 4 planes Surgery outlasting the drug selected Short, intermediate & long term local anesthetics Can increase duration & efficacy with opioids/LA admixture 5-10 mcg fentanyl or 1-2 mcg sufentanil Dose (mg) T-10 T-4 Lidocaine Tetracaine Bupivacaine Ropivacaine 30-50 mg 6-10 mg 6-10 mg 6-10 mg 75-100 mg 12-15 mg 12-15 mg 12-15 mg Duration Plain w/epi (0.2 mg) 45-60 min 60-90 min 90 min 90 min 60-90 min 120-180 min 140 min 140 min

Onset Drug Dose (min) Peak effect (min) Duration (hrs) Morphine 0.1-0.25 mg 30 60 12-24 Fentanyl 10-25 mcg 5 10 2-3 Sufentanil Meperidine 5-10 mcg 10 mg 5 10 10 15 2-4 4-5 Advantages Long duration Disadvantages Significant side effects; delayed respiratory depression; biphasic modality Rapid onset Short duration Rapid onset; few side effects Short duration; can see sinusoidal fetal HR; respiratory depression > fentanyl Rapid onset; potentiation of spinal anesthesia Nausea and vomiting; pruritis significant

 Definition of determining level: analgesia versus anesthesia  Alcohol skin wipe  Pinch  “toothpick” skin test  Nerve stimulator  Etc., etc., etc.  Beware: break no skin, use no needles

 Work fast after local anesthetic injected  Assess early and frequently  Augment position changes to maximize spread hyper / hypo baric solutions early  ?  Co-administration of IT Opioids Make patient cough several times More effective with lidocaine

 Use previously discussed strategies  Re-do spinal anesthetic  Supplementation with local anesthetic per surgeon  Analgesic intravenous supplements  Dissociative intravenous supplements  General Anesthesia

Spinal Anesthesia Group   50-100 mcg during injection with 2 mg midazolam General Anesthesia Group   Standardized Induction Desflurane or Sevoflurane *Sig p < .05 200 100 TO TA L H ia os pi ta lT im e Ti m e e ne st he s Time from Surgical Start to First Postoperative Analgesic Request 50-100 mg/kg/hr Fentanyl supplementation   2-injection technique  20 ml Bupivacaine 0.5% with epinephrine (1:200,000) Propofol Infusion  300 0 Followed customized format  400 A  SD) IA Injection 15 min before incision by anesthesia in holding Spinal Intraarticular General 500 (Mean Intraarticular Group  * Su rg ic al Ti m  10-12 mg Hyperbaric Bupivacaine Supplemental Anxiolysis & fentanyl Time in Minutes   Time Requirements between Groups 600 800 Time in Minutes ( SD)  Spinal Intraarticular General 700 600 500 400 300 200 100 0 * *Sig p < .05

 Placement of Local Anesthetic into epidural space Dural Rent

 Indications Orthopedic Major hip/knee surgery, pelvic fractures OB/GYN C-section; laboring analgesia/female pelvic organs Urology Prostate, bladder procedures General Surgery Upper & lower abdominal procedures* (height of block) Postoperative analgesia, combination with GA to reduce requirements *Thoracic vs Lumbar) Pediatric Procedures (*usually through caudal) Penile procedures, IHR, Ortho procedures; Postoperative analgesia, combination with GA to reduce requirements Vascular Surgery Vascular reconstruction, amputations Thoracic Surgery Postoperative analgesia, combination with GA to reduce requirements (*Thoracic epidural) Medical Conditions  Known/suspected MH Contraindications   Same as SAB ( ? Tattoos  Epidural blocks can be placed 4 hrs after last dose of SQ Heparin, 12 hrs after last dose of LMWH  NSAIDS (including ASA) not contraindicated  Placement relatively safe with INR < 1.5

 Typically use Loss of Resistance Technique  Routinely placed in Lumbar region   Use the needle for skin infiltration to identify midline structures Insert the needle in a slightly cephalad direction Dorsum of non-injecting hand rests on patient’s back  Thumb and index finger grasp hub of needle  Seat needle into intraspinous ligament and advance in slightly cephalad direction with continuous pressure on plunger of syringe and when the needle exits ligamentum flavum feel sudden loss of resistance   The distance from skin to epidural space is 4-6 cm in 90% of the population    Never change the direction of the needle tip after it passes through the ligamentum flavum Do not advance the needle Air versus Normal Saline   Missed dermatomes Presence of parasthesias?

 Thread catheter 3-5 cm  Check position   Remove needle while keeping positive pressure on catheter (thread concurrently)   Check position Secure catheter   Presence of parasthesias? Check position Test dose  Aspirate for Blood or CSF   Off midline insertion usually results in higher blood vessel puncture  A change of 20% or greater in HR after test dose indicates intravascular injection (replace catheter)  A dense motor block within 5 minutes after test dose indicates spinal block (if positive either replace catheter or convert to continuous spinal technique)  Only give test dose after contraction is over in pregnant women  If patient on beta blocker a change in systolic pressure > 20 mm Hg indicates intravascular injection 1.5 % Lidocaine with epinephrine vs 2% Lidocaine

Problem Interpretation Reason Action Needle floppy, angles laterally Missed intraspinous ligament Entry off midline Reassess and redirect needle Hit bone < 2 cm on insertion Hit spinous process Missed interspace; spine flexion inadequate Identify interspace; redirect needle more caudal Hit bone > 4cm or > Contacted lamina Needle entry too lateral Redirect more midline or use paramedian approach Bony resistance all approaches Arthritic spine & ligaments Ossification of ligaments Use paramedian approach Cannot thread catheter Narrow epidural space; Missed epidural space, false loss of resistance Space not dilated Epidural needle too close to dura; catheter not in epidural space Dilates space with 20 ml NS Try rotating the needle slightly to change bevel direction Resistance to LA injection, difficulty passing catheter, clear fluid in catheter, cold fluid in catheter Drip back of LA Cold fluid = LA; may be in subdural space Can be widespread patchy block with hemodynamic stability; replace catheter and wait for resolution Pain (parasthesia) with catheter insertion Catheter near nerve root Approach too lateral; too much catheter in epidural space If pain persists replace catheter; withdraw catheter if > 5 cm and reassess Can’t palpate spinous process Obesity or arthritis (obscuring spinous processes) Obesity; severe arthritis Try midline approach for obese Use 22 g needle to identify bony landmarks Use paramedian approach

Drug Concentration (%) Onset (min) Duration Plain/Epi (min) 2-Chloroprocaine 3 10-15 45-60/60-90 Lidocaine 2 10-15 80-120/120-180 Mepivacaine 1-2 15 90-160/160-200 Bupivacaine 0.25-.375 (*not surgical suitable) 0.5-.75 (*.75 -Not on OB) 15-20+ 160-220/180+ 15-20 15-20 120-200/150+ 0.5 – 0.75 15-20+ 140-180/150+ 0.5 15-20 160-220/180+ Etidocaine Ropivacaine Levobupivacaine

  Volume is the key factor in determining height of blockade Typical loading dose is 10-20 ml given in 5 ml increments Wait about 2-3 minutes between increments Use of epinephrine and bicarbonate will speed up onset on anesthesia If block incomplete after bolus replace catheter rather than wasting time giving larger dose or re-positioning catheter  Inject one-quarter to one-third of initial dose about 15 minutes after initial bolus to enhance sensory blockade     Cookbook guideline  To determine volume you can use the 5-foot rule  Example: For an individual who is 5 feet in height you administer 1 ml of local anesthetic solution for each segment requiring blockade and increase the volume by 0.1 ml for every 2 inches above 5 feet.  Example: For someone 5’10” in height and you enter at L3-L4 Interspace and want a to block up to T-6.  8 ml for L3-S5 and 7 ml for L2-T6 = 15 ml (base amount)  Additional amount is 0.1 ml times 5 (10 inches/2) = 0.5 times 15 segments = 7.5 (supplemental amount)  Overall add the 15 ml plus the 7.5 ml to get a dose of 22.5 ml Need a total of 22.5 ml to achieve a T-6 level on a 70” person

 Opioids  Morphine, Fentanyl, Sufentanil, Depo-Dur   Clonidine   Depo-Dur Considerations Hemodynamic Considerations Sodium Bicarbonate  Speeds onset & Prolongs duration

 CSE technique   Allows for immediate relief of pain (from SAB) & subsequent administration of medications via CLE for prolonged anesthesia Advantages   Reported to decrease failure rates of CLE (confirmation of epidural placement) Clinical uses:    General Surgery Laboring analgesia & Cesarean Section High risk patients  Slower onset of sympathetic blockade  Careful positioning during SAB with subsequent titration of CLE  Administration of intrathecal opioids with small amount of bupivacaine (2.5-5 mg) decreases epidural dosing requirements and decreases degree of sympathectomy

  CSE offers the advantages of both spinal and epidural anesthesia CSE provides rapid onset and careful titration  Can use doses as low as 40 mg lidocaine or 7.5 mg bupivacaine  Additional Opioids     Sufentanil Fentanyl Morphine Potential disadvantages PDPHA  Catheter migration into SA space  Test Dose  Transient parasthesias   Ideal length of spinal needle beyond epidural needle is 12-13 mm  Longer spinal needles associated with higher incidence

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