Spinal Anesthesia Student Notes PDF

SPINAL ANESTHESIA NRAN 80516 SUMMER 2024 RON ANDERSON, M.D. SPINAL ANESTHESIA HISTORY ANATOMY PHYSIOLOGIC EFFECTS Neurologic Cardiovascular Respiratory Gastrointestinal Renal Endocrine-Metabolic TECHNIQUE PHARMACOLOGY CONTRAINDICATIONS COMPLICATIONS CONTROVERSY KEY POINTS Anatomical Concerns Bony La...

SPINAL ANESTHESIA NRAN 80516 SUMMER 2024 RON ANDERSON, M.D. SPINAL ANESTHESIA HISTORY ANATOMY PHYSIOLOGIC EFFECTS Neurologic Cardiovascular Respiratory Gastrointestinal Renal Endocrine-Metabolic TECHNIQUE PHARMACOLOGY CONTRAINDICATIONS COMPLICATIONS CONTROVERSY KEY POINTS Anatomical Concerns Bony Landmarks Normal curvatures of the spine Ligaments traversed during spinal and epidural anesthesia Meninges – Location, nature, and function Distal termination of the spinal cord It is critical to know the sensory levels needed for various surgeries and the anatomical landmarks associated with those levels. Sympathetic, sensory and motor block will reach different levels following spinal and epidural anesthesia. Understand the physiologic consequences, particularly hemodynamic consequences and the prevention and management of them. Advantages and disadvantages of: Cutting versus pencil point needles Lateral versus sitting position Midline versus paramedian approach 3 KEY POINTS After injection of drug in the subarachnoid space, positioning and monitoring of block height should occur rapidly as you will have little time to modify block height with position changes. The primary determinant of duration of spinal anesthesia is proper drug selection. For the common local anesthetics used for spinal anesthesia, understand: Typical doses and reasons to modify them Use of additives to the local anesthetics (and consequences) Onset and duration Understand the contraindications to spinal anesthesia Know the complications and management of them, in particular: PDPHA Total spinal Neurologic injury Drug and positon (procedure) concerns with TNS (transient neurologic symptoms). Technique and indications for CSE (combined spinal-epidural). 4 HISTORY 1890s Germany – Frederich von Esmarch – Heinrich Quincke 1891 – attempted treatment of hydrocephalus by drainage of CSF through a needle in the lumbosacral region – August Bier and August Hildebrant 1898 – reported effects of spinal anesthesia with cocaine given to each other ANATOMY VERTEBRAE LIGAMENTS Supraspinous Interspinous Ligamentum Flavum Anterior and Posterior Longitudinal MENINGES Dura mater Arachnoid mater Pia mater SPINAL CORD VERTEBRAE 33 Vertebrae – – – – 7 cervical 12 thoracic 5 lumbar 5 sacral (fused) S5 not fused posteriorly – 4 coccygeal (fused) STOELTING, MILLER VERTEBRAL LANDMARKS STOELTING, MILLER VERTEBRAL ANATOMY Consider: – Angle of the spinous processes – Natural curvatures of the spine – Abnormal curvatures of the spine – Effect of positioning on above Lumbar vertebra Interlaminar foramen – Spaces formed between the spinous processes – Triangular shaped Base is formed by upper edge of the lower vertebra’s lamina – Flexing slides the articular processes upward enlarging the interlaminar foramen 10 CURVATURES OF THE SPINAL COLUMN Cervical and lumbar curves are convex anteriorly Thoracic and sacral curves are convex posteriorly Supine position – Spinal curves have significant impact on spread of local anesthetics (LA) – High points of the cervical and lumbar curves are at C5 and L5 – Low points of the thoracic and sacral curves are at T5 and S2 BARASH 11 LIGAMENTS OF THE SPINAL COLUMN Ligamentum Flavum Interspinous Ligament Supraspinous ligament MILLER MILLER LIGAMENTUM FLAVUM Thickest in the midline – 3–5 mm at the L2–3 interspace of adults – Farthest from the spinal meninges in the midline – Midline insertion of an epidural needle is least likely to result in unintended meningeal puncture “wet tap” MILLER 13 LONGITUDINAL LIGAMENTS Two other ligaments not penetrated during spinal or epidural anesthesia are: – Anterior and posterior longitudinal ligaments – Run along the anterior and posterior surfaces of the vertebral bodies – Provide stabilization 14 MENINGES Dura mater – Outermost, thickest of the meninges – Potential space exists between dura and arachnoid (subdural space) May see subdural injection in: – Less than 1% of intended epidurals – Up to 10% of intended subarachnoid blocks Arachnoid mater – Delicate, avascular membrane – Primary barrier to movement of drug from epidural space to spinal cord – Subarachnoid space between arachnoid and pia mater contains CSF – contiguous with cranial CSF MENINGES Pia mater – Closely adherent to spinal cord – Connected to arachnoid mater by trabeculae – Fenestrated – At tip of spinal cord, becomes the filum terminale, anchoring the cord to the sacrum SPINAL MENINGES MENINGES MENINGES SPINAL CORD Development – 1st Trimester Fetus Spinal cord extends entire length of vertebral column – Term newborn Spinal cord ends at L3 – Adult 60% end at L1 30% end at L2 10% end at L3 – Flexion of the vertebral column produces slight cephalad movement of the distal end of cord SPINAL CORD 31 pairs of Spinal nerves – Anterior motor root – Posterior sensory root Dermatome – Skin area innervated by a given spinal nerve Cauda equina – Spinal nerves which extend beyond the end of the spinal cord MILLER CROSS-SECTION AT L4 LEVEL MILLER SPINAL DERMATOMES STOELTING, MILLER SPINAL CORD BLOOD SUPPLY Arterial – Two posterior spinal arteries Supply the dorsal, sensory portion of cord Have extensive collateral supply from subclavian and intercostals – Single anterior spinal artery Originates from the vertebral artery Supplies the ventral, motor portion of cord Artery of Adamkiewicz – Largest anastomotic link of anterior spinal artery – Comes from the aorta, typically entering on the left at the L1 vertebral foramen – Crucial to blood supply of lower 2/3 of anterior cord Anterior Spinal Artery Syndrome – Bilateral lower extremity motor weakness SPINAL CORD BLOOD SUPPLY Venous – Extensive venous plexus located primarily in the lateral epidural space – Drains into the azygous vein and then the vena cava – Increased abdominal pressure or a mass compressing the vena cava may dilate this venous plexus, increasing: Probability of puncturing a vein during epidural placement Spread of local anesthetic due to decreased effective volume of epidural space SPINAL CORD BLOOD SUPPLY SENSORY LEVELS REQUIRED FOR COMMON SURGERIES STOELTING, MILLER STOELTING, MILLER PHYSIOLOGIC EFFECTS NEUROLOGIC CARDIOVASCULAR RESPIRATORY GASTROINTESTINAL RENAL ENDOCRINE-METABOLIC NEUROLOGIC EFFECTS Site of action of central neuraxis anesthesia not completely understood STOELTING, MILLER DIFFERENTIAL BLOCK Clinically – Increasing concentrations of local anesthetic will usually produce blockade in the following sequence: Autonomic Sensory Motor Preganglionic sympathetics Pain, temperature Large motor B fibers Small A fibers Large A fibers C fibers Useful in performance of differential block for diagnosis in pain management. Sympathetic, sensory, and motor block will reach different levels following central neuraxis anesthesia. CLINICAL CONSEQUENCES OF DIFFERENTIAL SPINAL BLOCK Sympathetic block – 2-6 levels above sensory block Motor block (and sometimes proprioception) – 2-3 levels below sensory block Likely due to decreasing concentrations of local anesthetic in CSF as a function of distance from the injection site. Problems: – May be distressing to the patient – Sympathectomy CARDIOVASCULAR EFFECTS Hypotension and bradycardia – Primarily due to blockade of sympathetic efferents Related to block height – Risk factors for hypotension Age > 50 years Hypovolemia Concurrent general anesthesia Addition of phenylephrine to local anesthetic – Risk factors for bradycardia Age < 50 years ASA 1 physical status classification β- blockade HEMODYNAMIC CHANGES HYPOTENSION BRADYCARDIA Due to both arterial and venodilation Blockade of cardioaccelerator fibers at T1- T4 Decreased preload causes cardiac stretch receptors to reflexively slow HR Multiple case reports of 20 and 30 heart black, as well as severe bradycardia and asystole during spinal and epidural anesthesia – Venodilation likely makes the bigger impact – Decreased preload is primary cause of decreased cardiac output with a high spinal BARASH TREATMENT OF HEMODYNAMIC CHANGES Prehydration – 500 – 1500 ml of crystalloid has been shown to reduce hypotension in some studies – Does not reliably protect against hypotension Vasopressors – Ephedrine 5-10mg boluses α+β preferable to pure α agonist When to treat – guidelines only – 25-30% drop from baseline BP – HR < 50-60/ min RESPIRATORY EFFECTS Typically minimal Accessory muscles of respiration can be compromised by high block – Caution when used in patients dependent on accessory muscles – Patients may complain of dyspnea due to lack of sensation of the chest wall moving Typically responds to reassurance Rare episode of respiratory arrest related to hypoperfusion of brainstem respiratory centers, not phrenic paralysis – Responds to improvement in cardiac output and/or blood pressure GASTROINTESTINAL EFFECTS Sympathectomy produces unopposed parasympathetic activity – – – – Increased secretions Relaxation of sphincters Increased peristalsis Constriction of the bowel May improve surgical conditions Nausea/vomiting associated with: Hypotension Block height greater than T5 Opiods History of motion sickness OTHER EFFECTS RENAL – May see urinary retention following both spinal and epidural anesthetics – Is this more severe than in patients receiving parenteral narcotics? ENDOCRINE-METABOLIC – Spinal and epidural anesthesia inhibit the surgical stress response Due to blockade of afferent sensory input Greatest effect with lower extremity and lower abdominal surgery – Unclear whether morbidity and mortality are reduced but evidence is accumulating TECHNIQUE NEEDLE SELECTION PREPARATION Drug Selection Sedation POSITION Sitting Lateral Decubutis Prone PUNCTURE Midline Paramedian Taylor POST-BLOCK POSITIONING NEEDLE SELECTION CSE NEEDLE ADVANTAGES OF VARIOUS STYLE SPINAL NEEDLES Two basic styles: – Cutting (e.g. Quincke) – Pencil point (e.g. Whitacre, Sprotte) A smaller gauge, pencil-point needle produces fewer PDPHAs than a larger gauge, cutting type needle Cutting needle – Sharper, easier to get through skin, no introducer needed unless very small needle used Pencil point – Decreased PDPHA – “Better” tactile feel PREPARATION Drug selection appropriate to duration and unique features of procedure – Which local anesthetic? – Addition of: Vasoconstrictor Alpha-2 agonist Narcotic – Fentanyl vs. Morphine – Hyperbaric vs. hypobaric vs. isobaric Sedation of the patient – Fine balance between relaxed + cooperative and asleep - particularly in elderly POSITION! POSITION! POSITION! Extremely important in successfully placing the block LATERAL DECUBITIS POSITION Hyperbaric Operative side down Hypobaric Operative side up Comfortable for patient Easy position to maintain during sedation Knees flexed Shoulders rounded Lower back bowed out MILLER SITTING POSITION Useful in morbidly obese patients or those with difficult anatomy Useful when a low level is desired, as in perineal surgery If a higher level is required, immediately after injection place patient in supine position Feet resting on stool Keep low back bowed out to minimize lumbar lordosis MILLER POSITIONING Prone – Usually in the jackknife position when surgery will require this position – Allows patient to position themselves – Useful for rectal, perineal procedures – May require gentle aspiration on needle as CSF won’t flow uphill. – Also used (not jackknife) for caudal epidural placement in adults PREP AND DRAPE Monitors on Sedation as appropriate Oxygen as needed – Usually nasal cannula adequate Do a good, WIDE prep with betadine, chlorhexidine, etc – You may not be successful at your chosen interspace Drapes – Pay particular attention to maintaining a sterile field. – Once you lay the drape on, don’t pick it back up and move it Clear plastic Paper Sterile towels SKIN AND SUBQ ANALGESIA Identify the L3-4 or L4-5 interspace – Certainly no higher than L2-3 Starting near the bottom of the chosen interspace, create a skin wheal of 1% lidocaine with a 25ga or smaller needle Inject to a depth of 1-2” in direction of anticipated spinal needle travel. Base depth of injection on patient’s body habitus STYLETS AND INTRODUCERS Stylets – Tight fitting – Prevent plugging of needle and carrying tissue into the epidural or subarachnoid space Introducers – Typically 18gauge ~ 1 ½ inches – Prevents smaller needle and pencil points from bending or getting misdirected – The introducer can reach the subarachnoid space in some people – If redirecting the needle, you must pull it back into introducer and redirect introducer first MIDLINE APPROACH Insert needle: – Midline – Nearer the bottom of the interspace – With a 100 -150 cephalad angle – Anchor introducer in interspinous ligament ADVANCING THE NEEDLE Many ways to hold needle, you will find what works best for you Goals: – Absolute control of needle depth – Tactile sensation of different tissues and perforation of the dura Distinction between ligament and paraspinous muscle which is entered if you deviate from midline Distinct “pop” felt on puncturing the dura, especially with a pencil point needle MIDLINE APPROACH MILLER CONTACT WITH BONE What went wrong? – Too steep an angle – Directed caudad – Started in the wrong place Pull needle back to subQ tissue and redirect, otherwise: – Needle may bend – Won’t reliably redirect PARAMEDIAN APPROACH Valuable in patients who are unable to reduce their lumbar lordosis – Some elderly males – Fusion – You gave a bit too much sedation – Pain E.g. Hip fracture PARAMEDIAN APPROACH MILLER TAYLOR APPROACH Paramedian approach at L5-S1 Same merits as discussed with the paramedian approach MILLER PARESTHESIAS Typically transient pain “shooting” into buttocks or down leg Needle likely deviated from midline or paramedian approach needs angle adjustment NEVER INJECT INTO A PARESTHESIA Pull the needle back to subQ and redirect in opposite direction of side which produced paresthesia CSF!!! When you feel the “pop” of puncturing the dura: – Advance the needle slightly (1-2 mm) Particularly important with pencil point needle where hole is not at end of needle – Remove the stylet – CSF should flow freely If not, rotate the hub 90 degrees – If CSF flows freely, – ANCHOR the needle on patients back and – Attach syringe with local anesthetic – Aspirate gently CSF should swirl in your local syringe INJECTING YOUR LOCAL If CSF aspirates freely, inject your local over 5 – 10 seconds. Re-aspiration – Some never – Some in the middle – Some at the end The key is to securely anchor the needle against the patient’s back so it doesn’t move Remove syringe andneedle Position patient POST-BLOCK POSITIONING Immediately position patient to achieve desired block height Within 1-2 minutes begin to assess development of block – Sympathetic – Sensory Reposition as necessary to modify block height – After ~ 5 minutes you won’t be able to affect much change Actively monitor patient’s hemodynamic status – Frequent blood pressures PHARMACOLOGY LOCAL ANESTHETICS Individual Drugs Baricity ADDITIVES BLOCK HEIGHT ONSET DURATION PHARMACOLOGY Principle Goals: Adequate block height of analgesia for proposed surgery Adequate duration of block for anticipated length of surgery LOCAL ANESTHETICS Drug selection is primary determinant of duration of spinal block Short acting – Procaine, lidocaine, mepivacaine, chloroprocaine Longer acting – Tetracaine, bupivacaine, ropivacaine, levobupivacaine SHORT-ACTING SPINAL ANESTHETICS Procaine (50-150 mg) Relative to lidocaine : – – – – More frequent nausea Higher failure rate Slower recovery Decreased incidence of TNS Lidocaine (60-70 mg) – TNS develops most commonly following outpatient surgery in the lithotomy and knee arthroscopy positions – Recommendations: Limit dosage to 60-70 mg Reduce concentration from 5% to 2.5% or less Mepivacaine (30-60 mg) – Slightly longer acting than lidocaine – Similar to slightly lower incidence of TNS Chloroprocaine (40-60 mg) – Hx of problems in past with preservatives and large epidural doses getting subarachnoid – Excellent analgesia with 40-60mg with little or no incidence of TNS – Do not add epinephrine LONG-ACTING SPINAL ANESTHETICS Ropivacaine and Levobupivacaine – No advantage over bupivacaine in doses used for spinal anesthetics. May have protective value in epidural doses Tetracaine (12-15 mg) Longest acting spinal anesthetic when vasoconstrictor added – May increase the incidence of TNS which is otherwise low Packaged as: – Niphanoid crystals 20mg » Reconstitute with 2 ml sterile water to give a 1% solution » Mix with equal volume D10 producing a hyperbaric 5 mg/ml solution – 1% solution Bupivacaine (12-15 mg) Hyperbaric 0.5% and 0.75% solution prepackaged in dextrose Isobaric 0.5% and 0.75% plain solutions – Is it really isobaric? Levobupivacaine (12-15mg) Ropivacaine (15-25mg) SPINAL DOSING STOELTING, MILLER BARASH ADDITIVES Vasoconstrictors – Usefulness varies with local anesthetic used Epinephrine (0.1 – 0.2mg, max 0.5mg) Phenylephrine (2 – 5mg) – Cautions: Lidocaine – Addition of vasoconstrictors may increase neurotoxicity Chloroprocaine – Addition of epinephrine may produce “flu-like” effects Tetracaine – Epinephrine or phenylephrine may increase incidence of TNS OTHER ADDITIVES Clonidine (25-150mcg) Increases duration and quality of block Inhibition of nocioceptive afferents Has been shown in some studies to exacerbate hypotension Narcotics – Mimic endogenous enkephalins at the dorsal horn Fentanyl (12.5 – 25mcg) Morphine (0.1 - 0.5mg) – May produce some pain relief for up to 18-24 hours – May produce respiratory depression Neostigmine – Release of nitric oxide in spinal cord prolongs and intensifies analgesia BLOCK HEIGHT MILLER MILLER BLOCK HEIGHT So what really makes a difference, other than drug dose and baricity? CSF volume Accounts for ~80% of variability in block height Patient position Age But less important than the others ONSET AND DURATION Onset to peak block height – Lidocaine and mepivacaine 10-15 minutes – Tetracaine and bupivacaine 20+ minutes Primary determinant of duration is drug selection – 2-Dermatome regression – Complete resolution Duration at surgical site CONTRAINDICATIONS APPROPRIATE FOR PLANNED SURGERY? PATIENT REFUSAL PATIENT’S INABILITY TO REMAIN STILL INCREASED INTRACRANIAL PRESSURE COAGULOPATHY INFECTION AT SITE/ SEPSIS SEVERE HYPOVOLEMIA AORTIC OUTLET OBSTRUCTION PRE-EXISTING NEUROLOGIC DISEASE? CONTRAINDICATIONS Is a spinal appropriate for the planned surgery? Is the anatomic location amenable to a spinal anesthetic? Will the duration of surgery exceed that of your block? Does the patient’s mental status make them a candidate for regional anesthesia? Patient refusal Often cited as the only “absolute” contraindication to regional anesthesia CONTRAINDICATIONS Patient’s inability to remain still Given an alternative, the risk is not worth it Increased intracranial pressure Potential for risk of herniation if CSF is removed May further increase ICP if large volumes injected into epidural space Benign intracranial hypertension (pseudotumor cerebri) not a contraindication since pressure is globally elevated CONTRAINDICATIONS Coagulopathy Increased risk of epidural hematoma, particularly in association with LMWH Infection at insertion site/ Sepsis Increases the risk of meningitis Severe hypovolemia or shock Increased risk of hypotension CONTRAINDICATIONS Aortic outlet obstruction E.g. severe aortic stenosis Acute reduction in afterload compromises aortic pressure and subsequently coronary perfusion pressure Pre-existing neurologic disease Particularly in diseases like MS that have intermittent exacerbations Has been incorrectly considered a contraindication due to legal concerns Does not preclude regional anesthesia, but warrants a more thorough discussion with the patient COMPLICATIONS POSTDURAL PUNCTURE HEADACHE (PDPHA) Incidence Prevention Management BACKACHE HEARING LOSS TOTAL SPINAL NEUROLOGIC INJURY POST DURAL PUNCTURE HEADACHE Location – Frontal, occipital, or both Nature – Dull or throbbing KEY FEATURE – POSTURAL Time frame – Typically 12-48 hours following puncture – May rarely occur immediately Mechanism – Loss of CSF through hole in dura causes the brain to be displaced downward, causing traction on sensitive structures POST DURAL PUNCTURE HEADACHE Risk Factors – Cutting needle (e.g. Quincke) Pencil point needles have greatly reduced the incidence of PDPHA due to: ? – Less cutting of the fibers vs. – Greater inflammatory response with pencil point – Needle size – Age Low risk in children Increases in puberty Decreases again in elderly – Pregnancy vs. female gender – Previous history of PDPHA POST DURAL PUNCTURE HEADACHE MILLER MANAGEMENT OF PDPHA Old school – Forced fluids, bedrest, caffeine (po or IV) Definitive – Epidural Blood Patch Epidural needle placed 15-20 ml of blood removed from patient in sterile fashion Slow injection of blood into the epidural space – Try to go at same interspace as previous puncture » If unable, go lower. MRI studies show significantly more spread of blood in a cephalad direction than caudad ~90% effective COMMENTS ON EPIDURAL BLOOD PATCH Remarkably effective treatment Must use strict aseptic technique A basic neurologic history and physical is warranted prior to the procedure – Subdural hematoma – New onset of neurologic symptoms Post procedure instructions –you must document this! – Bed rest, no lifting for 24 hours – Force po caffeine-containing fluids – Normal things they should expect: Low grade fever Mild backache – Return to the Emergency Room immediately for: High fever Severe backache New neurologic symptoms – Incontinence – Numbness – Worsening of headache COMPLICATIONS Backache – Usually minor and brief, may occur in ~10% – Etiology uncertain, possible causes include: Needle trauma Local anesthetic irritation Ligamentous strain Surgical positioning Hearing loss – – – – Transient, mild decrease lasting 1-3 days Incidence up to 40% 3:1 Female to male predominance Etiology unclear COMPLICATIONS Total spinal – Block of the entire spinal cord and possibly brainstem resulting in: Profound hypotension and bradycardia from sympathetic block Possible respiratory arrest – Management: Cardiovascular support – Vasopressors, fluids, atropine Respiratory support – Ventilation, oxygenation COMPLICATIONS Neurologic injury – Serious injury is rare (0.03 – 0.1%) Not proven to be causative in all these cases – Most commonly Limited motor weakness Persistent paresthesia – Etiologies Direct needle trauma Spinal cord ischemia Inadvertent injection of neurotoxic substance or bacteria Epidural hematoma – Local anesthetics can be neurotoxic in commonly used concentrations Maldistribution can cause injury – e.g. spinal microcatheters CONTROVERSY APPROPRIATE FOR OUTPATIENT ANESTHESIA? USE OF SPINAL MICROCATHETERS? BENZODIAZIPINES FOR SEDATION? IMPROVED LONG-TERM OUTCOME WITH REGIONAL ANESTHESIA? COMBINED SPINAL-EPIDURAL? REIMBURSEMENT OF POSTOPERATIVE PAIN MANAGEMENT????? CONTROVERSY Is spinal anesthesia appropriate for outpatient anesthesia? – Concerns: PDPHA Urinary retention Lidocaine and TNS – Alternatives to idocaine – Length (cost) of extended PACU stay Are spinal microcatheters safe? Is there a patient or procedure that can only be done with a continuous spinal? GUIDELINES FOR CONTINUOUS SPINAL CONTROVERSY Are benzodiazipines appropriate for sedation with regional anesthesia? – Pros Excellent sedative drugs May raise seizure threshold – Cons Resuscitation following cardiac collapse from local anesthetic toxicity more difficult with diazepam on board May mask early symptoms, delaying appropriate therapy – A reasonable discussion if talking about the large local anesthetic doses required for epidurals, but a non issue for spinal anesthesia Is long-term outcome improved following regional anesthesia? – Decreased surgical stress response – Modification of surgical effects on fibrinolytic system – Translation of findings to long-term morbidity and mortality CONTROVERSY Combined spinal-epidural anesthesia – Used most frequently in obstetrics Cesarean section – Gives excellent spinal analgesia for surgery – Allows postoperative epidural for pain control – May delay ambulation, or add risk/impact staffing Labor – Systematic review shows little difference between CSE and epidural analgesia – Useful in surgery which is of uncertain duration and amenable to central neuraxis block – Useful for postoperative pain management ADVANTAGES OF CSE CONTROVERSY Reimbursement – If we determine that improved postoperative pain management reduces morbidity and/or mortality, therefore reducing overall health care costs, how will anesthesia providers be reimbursed for that service? – Increased workload – Increased liability THE ANESTHETIC RECORD CHARTING YOUR SPINAL Sterile prep and drape with betadine. Skin wheal and deep infiltration with 25 gauge, 1 ½” needle. 25 gauge Sprotte via introducer to subarachnoid space x one attempt with return of clear CSF x four quadrants. Positive aspiration of CSF. 12.5 mg of 0.75% bupivacaine with fentanyl 25 mcg injected over 10 seconds. Needle removed. Pt placed in supine position. Patient tolerated procedure well. Bupivacaine lot# ---------. Expiration 10/2018 Fentanyl lot#-------- Expiration 10/2018 SP&D c betadine. Skin wheal & deep infilt. c 25 ga I ½”. 25ga Sprotte via intro to SAS X 1. Clear CSF x 4 quads. + asp CSF. 12.5 mg 0.75% Bup/Fentanyl 25mcg over 10 seconds. Needle removed. →supine. Tol. Well. Bup lot------exp10/20108 Fent lot----- exp 10/2018 SOURCE MATERIAL CLINICAL ANESTHESIA - 8th edition. Barash, Cullen, Stoelting MILLER’S ANESTHESIA – 9TH edition. Miller BASICS OF ANESTHESIA – 6th edition. Stoelting, Miller 97