Epidurals, Spinals, and Epidurals, Spinals, and MoreMore

April 2009April 2009

Dr. EismonDr. Eismon

Table of ContentsTable of Contents

Anatomy Anatomy TechniquesTechniques Side EffectsSide Effects Concerns of anticoagulationConcerns of anticoagulation

I think that Turkey is performing I think that Turkey is performing Gobblfication Gobblfication

AnatomyAnatomy

EpiduralEpidural Local anesthetics injected into the epidural space spread in cranial and Local anesthetics injected into the epidural space spread in cranial and

caudal directions from the level at which they are administered. caudal directions from the level at which they are administered. The drug bathes the nerve roots as they pass through the anterolateral The drug bathes the nerve roots as they pass through the anterolateral

epidural space, but roots above and below the limit of spread of local epidural space, but roots above and below the limit of spread of local anesthetic remain unaffected.anesthetic remain unaffected.

This gives an epidural local anesthetic block a top and a bottom level of This gives an epidural local anesthetic block a top and a bottom level of effect, with the site of injection somewhere in between. effect, with the site of injection somewhere in between.

There may be preferential spread of local anesthetic to one side of the There may be preferential spread of local anesthetic to one side of the spinal canal, and when this occurs the level and intensity of blockade on spinal canal, and when this occurs the level and intensity of blockade on each side of the body can be different.each side of the body can be different.

Occasionally single nerve roots are missed altogether resulting in a patchy Occasionally single nerve roots are missed altogether resulting in a patchy block. block.

Local anesthetic solutions injected into the epidural space are influenced Local anesthetic solutions injected into the epidural space are influenced by gravity. With the patient in a sitting position the lower segments tend to by gravity. With the patient in a sitting position the lower segments tend to be blocked, and when supine the block spreads higher. In the lateral be blocked, and when supine the block spreads higher. In the lateral position, the dependent side tends to block preferentially position, the dependent side tends to block preferentially

Friendly advice to pregnant Friendly advice to pregnant anesthesia residentsanesthesia residents

PositioningPositioning

ProcedureProcedure

A new twist for the Sitting positionA new twist for the Sitting position In the mid-calf position, the patient In the mid-calf position, the patient

rests the lower legs (mid-calf), rests the lower legs (mid-calf), rather than the knees, on the edge rather than the knees, on the edge of the bed, sitting somewhat further of the bed, sitting somewhat further back on the bed than in the back on the bed than in the conventional sitting position. As a conventional sitting position. As a result, the knees are slightly flexed result, the knees are slightly flexed with the patient’s back nearer to with the patient’s back nearer to the practitioner. The patient’s neck the practitioner. The patient’s neck is flexed forward and the arms are is flexed forward and the arms are crossed in front of the body (crossed in front of the body (Fig. 1Fig. 1).).

One advantage of the mid-calf One advantage of the mid-calf position is that the patient naturally position is that the patient naturally assumes an ideal position for assumes an ideal position for placement of a neuraxial block with placement of a neuraxial block with little instruction. The shoulders fall little instruction. The shoulders fall forward and the flexed position forward and the flexed position achieved appears to optimally open achieved appears to optimally open the spaces between the spinous the spaces between the spinous processesprocesses

British Journal of Anaesthesia 2006 97(4):583-584; British Journal of Anaesthesia 2006 97(4):583-584; doi:10.1093/bja/ael231 doi:10.1093/bja/ael231

Technical DifficultyTechnical Difficulty The fatness- most The fatness- most

problematic: get a problematic: get a harpoon and a lucky harpoon and a lucky charmcharm

Old people suck- calcified Old people suck- calcified ligaments and arthur is in ligaments and arthur is in town: you may have to town: you may have to abandon procedureabandon procedure

Prior back surgery- Heavy Prior back surgery- Heavy MetalMetal

Autoimmune + collagen Autoimmune + collagen d/o - have ligaments like d/o - have ligaments like paper don’t slip or you paper don’t slip or you might get a spinal tapmight get a spinal tap

Technical DifficultyTechnical Difficulty Kyphoscoliosis: this gentleman Kyphoscoliosis: this gentleman

looks virtually impossible to place looks virtually impossible to place neuraxial anesthesia but clinicians neuraxial anesthesia but clinicians used Taylors approach for spinal used Taylors approach for spinal anesthesiaanesthesia

In the sitting position, the right In the sitting position, the right posterior superior iliac spine (PSIS) posterior superior iliac spine (PSIS) was identified. A point 1cm below was identified. A point 1cm below and medial to the PSIS was and medial to the PSIS was marked, Using a Quincke type marked, Using a Quincke type spinal needle, the site was entered spinal needle, the site was entered in cephalomedial direction. Dural in cephalomedial direction. Dural puncture was successful at the puncture was successful at the second attempt.second attempt.

In patients where a midline In patients where a midline approach at the lumbar level is approach at the lumbar level is difficult, the lumbosacral approach difficult, the lumbosacral approach is an excellent alternative for is an excellent alternative for providing spinal anesthesia to providing spinal anesthesia to perineal and lower extremity perineal and lower extremity surgerysurgery

M.G.M. Medical College M.G.M. Medical College Indore Madhya Pradesh IndiaIndore Madhya Pradesh India

TattoosTattoos A Medline and EMBASE search of A Medline and EMBASE search of

the English literature using the key the English literature using the key words: spinal, epidural, tattoos, words: spinal, epidural, tattoos, tattooing, complications did not find tattooing, complications did not find any reports or concerns regarding any reports or concerns regarding neuraxial anesthesia through tattooed neuraxial anesthesia through tattooed areas. However, one might postulate areas. However, one might postulate that there could be long-term that there could be long-term implications from depositing a implications from depositing a pigmented tissue core in the epidural pigmented tissue core in the epidural or subarachnoid space. or subarachnoid space.

Based on the limited information Based on the limited information available it is possible that inserting available it is possible that inserting an epidural or spinal needle through a an epidural or spinal needle through a tattoo could cause long-term problems tattoo could cause long-term problems such as arachnoiditis or a neuropathy such as arachnoiditis or a neuropathy secondary to an inflammatory secondary to an inflammatory reaction, but we don’t know.reaction, but we don’t know.

Canadian Journal of AnesthesiaCanadian Journal of Anesthesia 49:1057-1060 (2002)49:1057-1060 (2002)

Epidural catheter placed detected by Epidural catheter placed detected by flouroscopyflouroscopy

SpinalSpinal

Physiological effect of spinal Physiological effect of spinal blockade at different levels blockade at different levels

DifferencesDifferences

CSE ZCSE Z

CSE FailureCSE Failure

CaudalCaudal Block of the sacral and lumbar Block of the sacral and lumbar

nerve roots. It is useful as a nerve roots. It is useful as a supplement to general anesthesia supplement to general anesthesia and for provision of postoperative and for provision of postoperative analgesia. This technique is analgesia. This technique is popular in pediatric patients. popular in pediatric patients. Catheter insertion may be Catheter insertion may be performed for continuous caudal performed for continuous caudal block.block.

The S5 processes are remnants and The S5 processes are remnants and form the cornua, which provide form the cornua, which provide the main landmarks for the main landmarks for indentifying the sacral hiatus. The indentifying the sacral hiatus. The hiatus is covered by the sacro-hiatus is covered by the sacro-coccygeal membrane. coccygeal membrane.

The canal contains areolar The canal contains areolar connective tissue, fat, sacral connective tissue, fat, sacral nerves, lymphatics, the filum nerves, lymphatics, the filum terminale and a rich venous terminale and a rich venous plexus. plexus.

Caudal Injection for Pain patientsCaudal Injection for Pain patients

Caudal epidural anesthesia in Caudal epidural anesthesia in children can be used inchildren can be used in

Lower abdominal surgeryLower abdominal surgery: (incision below the umbilicusT10 sensory level) : (incision below the umbilicusT10 sensory level) especially perineal, genitourinary or ilioinginual surgery. especially perineal, genitourinary or ilioinginual surgery.

Lower extremity surgery (hip, leg and foot)Lower extremity surgery (hip, leg and foot): though at times it is difficult to : though at times it is difficult to achieve a satisfactory block to the distal 1/3 of the foot. achieve a satisfactory block to the distal 1/3 of the foot.

Newborn and premature infantsNewborn and premature infants: If used as the sole anesthetic, caudal : If used as the sole anesthetic, caudal epidural anesthesia reduces the risk of respiratory depression from residual epidural anesthesia reduces the risk of respiratory depression from residual neuromuscular blockade (pancuronium) and inhalation anesthetics. Post-neuromuscular blockade (pancuronium) and inhalation anesthetics. Post-operative apnea associated with general anesthesia, is reduced with caudal operative apnea associated with general anesthesia, is reduced with caudal anesthesia but not abolished. anesthesia but not abolished.

Neuromuscular disease such as muscular dystrophyNeuromuscular disease such as muscular dystrophy . There is a high . There is a high incidence of postoperative respiratory failure due to a combination of incidence of postoperative respiratory failure due to a combination of general anesthesia and muscle weakness. Caudal epidural anesthesia general anesthesia and muscle weakness. Caudal epidural anesthesia indicated for lower extremity surgery (very common in these patients). indicated for lower extremity surgery (very common in these patients).

Malignant hyperthermiaMalignant hyperthermia: it is generally accepted that all local anesthetic : it is generally accepted that all local anesthetic agents are considered safeagents are considered safe

Caudal DosesCaudal Doses Pediatric populationPediatric population 0.5 ml/kg, 0.25% bupivacaine 0.5 ml/kg, 0.25% bupivacaine

(sacro-lumbar block)(sacro-lumbar block)1 ml/kg, 0.25% bupivacaine 1 ml/kg, 0.25% bupivacaine (upper abdominal block)(upper abdominal block)1.2 ml/kg,0.25% bupivacaine (mid-1.2 ml/kg,0.25% bupivacaine (mid-thoracic block)thoracic block)(Doses described by Armitage).(Doses described by Armitage).

Adults: 20-30 ml 0.25-0.5% Adults: 20-30 ml 0.25-0.5% bupivacaine. Average volume of bupivacaine. Average volume of the sacral canal is 30-35 ml.the sacral canal is 30-35 ml.

Epidural fat in children has a loose Epidural fat in children has a loose and wide-meshed texture, whereas and wide-meshed texture, whereas in adults it becomes more densely in adults it becomes more densely packed and fibrous. Hence, local packed and fibrous. Hence, local anesthetic spread is greater in anesthetic spread is greater in children.children.

Caudal Placement PositionCaudal Placement Position The sacral hiatus in an The sacral hiatus in an

infant or young child is infant or young child is easily identified because the easily identified because the landmarks are more landmarks are more superficial. The sacral hiatus superficial. The sacral hiatus is formed by failure of is formed by failure of fusion of the fifth sacral fusion of the fifth sacral vertebral arch. The remnants vertebral arch. The remnants of the arch are known as the of the arch are known as the sacral cornu, and are located sacral cornu, and are located on either side of the hiatus. on either side of the hiatus.

Caudal Block TechniqueCaudal Block Technique The pop felt is the needle The pop felt is the needle

piercing the sacrococcygeal piercing the sacrococcygeal membrane membrane

There should be very little There should be very little resistance to injection. resistance to injection.

The dura ends at S2, but may The dura ends at S2, but may extend further. Aspirate to extend further. Aspirate to confirm the absence of confirm the absence of blood/cerebrospinal fluid and blood/cerebrospinal fluid and inject local anesthetic while inject local anesthetic while feeling for inadvertent feeling for inadvertent subcutaneous injection with the subcutaneous injection with the other handother hand

In children, the block typically In children, the block typically performed after general performed after general anesthesia has been induced anesthesia has been induced and before surgery has and before surgery has commencedcommenced

The needle is inserted at a 60-degree angle and the needle is advanced until a "pop" is felt. The needle is then lowered to a 20-degree angle and advanced an additional 2-3 mm to make sure the bevel is in the caudal epidural space

CaudalCaudal

Neuraxial ContraindicationsNeuraxial Contraindications

Effects of Neuraxial anesthesiaEffects of Neuraxial anesthesia

Complications and side effects of Complications and side effects of neuraxial methodsneuraxial methods

Blood PatchBlood Patch

The epidural blood patch The epidural blood patch consists of injecting 5-20 mLs of consists of injecting 5-20 mLs of autologous blood into the autologous blood into the epidural space, in the region of epidural space, in the region of the suspected dural 'hole.' the suspected dural 'hole.'

Autologous blood is typically Autologous blood is typically drawn in a sterile fashion, and drawn in a sterile fashion, and then injected as a bolus into the then injected as a bolus into the epidural space. epidural space.

In 90% of cases, the response is In 90% of cases, the response is positive and immediate. positive and immediate. Subsequently, long-term relief Subsequently, long-term relief of PDPH occurs in the majority of PDPH occurs in the majority of cases of cases

PATIENTS ON HEPARIN THERAPYPATIENTS ON HEPARIN THERAPY There should be at least a 1-h delay between neuraxial needle placement There should be at least a 1-h delay between neuraxial needle placement

and heparin administration. and heparin administration. The epidural catheter should be removed 2–4 h after the last heparin dose The epidural catheter should be removed 2–4 h after the last heparin dose

and 1 h before subsequent heparin administration. and 1 h before subsequent heparin administration. Partial thromboplastin time (PTT) or activated coagulation time (ACT) Partial thromboplastin time (PTT) or activated coagulation time (ACT)

should be monitored to avoid excessive heparin effect. should be monitored to avoid excessive heparin effect. Dilute concentrations of local anesthetics are recommended to minimize Dilute concentrations of local anesthetics are recommended to minimize

motor blockade; the patient should be followed postoperatively for early motor blockade; the patient should be followed postoperatively for early detection of reoccurrence of motor blockade. detection of reoccurrence of motor blockade.

In the event of a traumatic (bloody) or difficult needle placement, there are In the event of a traumatic (bloody) or difficult needle placement, there are no data to support mandatory cancellation of surgery. no data to support mandatory cancellation of surgery.

PATIENTS RECEIVING LMWH AND NEURAXIAL ANESTHESIAPATIENTS RECEIVING LMWH AND NEURAXIAL ANESTHESIA Monitoring of anti-Xa level is not recommended.Monitoring of anti-Xa level is not recommended. The administration other anticoagulant medications with LMWHs may increase the The administration other anticoagulant medications with LMWHs may increase the

risk of spinal hematoma.risk of spinal hematoma. The presence of blood during needle placement and catheter placement does not The presence of blood during needle placement and catheter placement does not

necessitate postponement of surgery. However, the initiation of LMWH therapy necessitate postponement of surgery. However, the initiation of LMWH therapy should be delayed for 24 h postoperatively.should be delayed for 24 h postoperatively.

The first dose of LMWH prophylaxis should be given no earlier than 24 h The first dose of LMWH prophylaxis should be given no earlier than 24 h postoperatively and only in the presence of adequate hemostasis.postoperatively and only in the presence of adequate hemostasis.

In patients who are on LMWH, needle/catheter placement should be performed at In patients who are on LMWH, needle/catheter placement should be performed at least 12 h after the last prophylactic dose of enoxaparin or 24 h after higher doses least 12 h after the last prophylactic dose of enoxaparin or 24 h after higher doses of enoxaparin (1 mg/kg every 12 h), 24 h after dalteparin (120 U/kg every 12 h or of enoxaparin (1 mg/kg every 12 h), 24 h after dalteparin (120 U/kg every 12 h or 200 U/kg every 12 h), and 24 h after tinzaparin (175 U/kg daily).200 U/kg every 12 h), and 24 h after tinzaparin (175 U/kg daily).

There should be a 12-h interval between the last prophylactic dose of enoxaparin There should be a 12-h interval between the last prophylactic dose of enoxaparin and removal of the epidural catheter. For higher doses of enoxaparin, a 24-h delay and removal of the epidural catheter. For higher doses of enoxaparin, a 24-h delay is recommended.is recommended.

The LMWH may be administeredThe LMWH may be administered

Summary of Guidelines on Anticoagulants and Neuraxial BlocksSummary of Guidelines on Anticoagulants and Neuraxial Blocks I. Antiplatelet medications I. Antiplatelet medications Aspirin, NSAIDs, COX-2 inhibitorsAspirin, NSAIDs, COX-2 inhibitors

May continueMay continuePain clinic patients: Aspirin preferably stopped 2–3 days in thoracic and cervical blocksPain clinic patients: Aspirin preferably stopped 2–3 days in thoracic and cervical blocksEpidurals (author’s preference—see text) Epidurals (author’s preference—see text)

Thienopyridine derivativesThienopyridine derivativesa. Clopidogrel (Plavix)—discontinue for 7 daysa. Clopidogrel (Plavix)—discontinue for 7 daysb. Ticlopidine (Ticlid)—discontinue for 14 days Do not perform a neuraxial block in patients on more than one antiplatelet drug. b. Ticlopidine (Ticlid)—discontinue for 14 days Do not perform a neuraxial block in patients on more than one antiplatelet drug.

GPIIB/IIIA inhibitors: Time to normal platelet aggregationGPIIB/IIIA inhibitors: Time to normal platelet aggregationa. Abciximab (Reopro) = 24–48 ha. Abciximab (Reopro) = 24–48 hb. Eptifibatide (Integrilin) = 4–8 hb. Eptifibatide (Integrilin) = 4–8 hc. Tirofiban (Aggrastat) = 4–8 hc. Tirofiban (Aggrastat) = 4–8 hAntiplatelet medications (ASA, Plavix) are usually given after GPIIb/IIIa inhibitors. The above guidelines on aspirin and Plavix should be Antiplatelet medications (ASA, Plavix) are usually given after GPIIb/IIIa inhibitors. The above guidelines on aspirin and Plavix should be adhered to. adhered to.

II. WarfarinCheck INRII. WarfarinCheck INRINR ≤ 1.5 before neuraxial block or epidural catheter removalIII. HeparinINR ≤ 1.5 before neuraxial block or epidural catheter removalIII. Heparin

Subcutaneous heparin (5000 units SQ q 12 h)Subcutaneous heparin (5000 units SQ q 12 h)Subcutaneous heparin is not a contraindication against a neuraxial blockSubcutaneous heparin is not a contraindication against a neuraxial blockNeuraxial block should preferably be performed before SQ heparin is givenNeuraxial block should preferably be performed before SQ heparin is givenRisk of decreased platelet count with SG heparin therapy > 5 days Risk of decreased platelet count with SG heparin therapy > 5 days

Intravenous heparinIntravenous heparinNeuraxial block: 2–4 h after the last intravenous heparin doseNeuraxial block: 2–4 h after the last intravenous heparin doseWait ≥ 1 h after neuraxial block before giving intravenous heparin Wait ≥ 1 h after neuraxial block before giving intravenous heparin

IV. Low-molecular-weight heparin (LMWH)IV. Low-molecular-weight heparin (LMWH)No concomitant antiplatelet medication, heparin, or dextranNo concomitant antiplatelet medication, heparin, or dextran

LMWH PreopLMWH Preopa. Wait 12 h before a neuraxial block:a. Wait 12 h before a neuraxial block:b. Enoxaparin (Lovenox) 0.5 mg/kg bid (prophylactic dose)b. Enoxaparin (Lovenox) 0.5 mg/kg bid (prophylactic dose)c. Wait 24 h before a neuraxial block:c. Wait 24 h before a neuraxial block:d. Enoxaparin (Lovenox), 1 mg/kg bid (therapeutic dose)d. Enoxaparin (Lovenox), 1 mg/kg bid (therapeutic dose)e. Enoxaparin (Lovenox), 1.5 mg/kg qde. Enoxaparin (Lovenox), 1.5 mg/kg qdf. Dalteparin (Fragmin), 120 units/kg bidf. Dalteparin (Fragmin), 120 units/kg bidg. Dalteparin (Fragmin), 200 units/kg qdg. Dalteparin (Fragmin), 200 units/kg qdh. Tinzaparin (Innohep), 175 units/kg qd h. Tinzaparin (Innohep), 175 units/kg qd

LMWH Postop:LMWH Postop:a. LMWH should not be started until after 24 h after surgerya. LMWH should not be started until after 24 h after surgeryb. LMWH should not be given until ≥ 2 h after epidural catheter removal b. LMWH should not be given until ≥ 2 h after epidural catheter removal

Patients with epidural catheter who are given LMWHPatients with epidural catheter who are given LMWHThe catheter should be removed at the earliest opportunity.The catheter should be removed at the earliest opportunity.Enoxaparin (0.5 mg/kg): Remove the epidural catheter ≥ 12 h after last dose.Enoxaparin (0.5 mg/kg): Remove the epidural catheter ≥ 12 h after last dose.Enoxaparin (1-1.5 mg/kg), dalteparin, tinzaparin:Enoxaparin (1-1.5 mg/kg), dalteparin, tinzaparin:Remove the epidural catheter ≥ 24 h after last doseRemove the epidural catheter ≥ 24 h after last doseRestart the LMWH ≥ 2 h after the catheter removalRestart the LMWH ≥ 2 h after the catheter removalSummary recommendations for LMWH (preop & postop):Summary recommendations for LMWH (preop & postop):Wait 24 h except for patients on low-dose enoxaparin (0.5 mg/kg) in which case a 12 hWait 24 h except for patients on low-dose enoxaparin (0.5 mg/kg) in which case a 12 hinterval is adequate.interval is adequate.Wait 2 h after the catheter is removed before starting LMWH. Wait 2 h after the catheter is removed before starting LMWH.