POA: Regional Anesthesia – Flashcards
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Where does the spinal cord end in adults?
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L2
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What is the average distance from the skin to the epidural space?
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5 cm
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Which ion is most affected by local anesthetics?
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Na
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What is the sensory block level needed for caesarian section?
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T4
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Where is Tuffier's line located?
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L3-L4
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Local anesthetic with a specific gravity greater than CSF is called what?
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Hyperbaric
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Which local anesthetic is not used in spinal anesthesia?
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Ropivicaine
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What is the factor that most influences the duration of the anesthetic in spinal anesthesia?
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Dose, Choice of LA
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What dose of marcaine is best for knee anesthesia?
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8-12 mg
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What is the test dose used in epidural anesthesia?
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...
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What are the 8 advantages of regional anesthesia?
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Maintenance of Consciousness Skeletal muscle relaxation Blunts stress response to surgery Decreases intraoperative blood loss Lower incidence of thromboembolic events Postoperative analgesia Pain relief for nonsurgical patient Less N/V
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What factors determine the selection of regional anesthesia?
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Type of Surgery Length of Surgery Patient position Review of co-existing disease Anatomical area of block Neurologic abnormalities Abnormal bleeding Medications
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What level should a block to be done to for a knee procedure?
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T10
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What is the most common reason for a failed block?
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Did not wait long enough for the block to take efect
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What is the main disadvantage of regional anesthesia? What condition exacerbates it?
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Hypotension Made worse by hypovolemia
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What is the only absolute contraindication to regional anesthesia?
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Patient refusal
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What are some relative contraindications to regional anesthesia?
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Nerve block hinders surgery Infection at puncture site Sepsis Coagulopathy Increased ICP Musculoskeletal deformities Increased IOP Hypovolemia CNS disease (MS, etc.) Chronic back pain
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What can be caused when placing a regional anesthetic into the interthecal space with a patient with a high ICP?
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Brain herniation
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What are two main factors that must be considered when choosing between RA and GA?
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Can the patient cooperate? Is the surgical site appropriate?
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What surgeries are appropriate for neuraxial anesthesia techniques?
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Surgery on lower abdomen or extremities
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What are some primary advantages for doing RA?
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Ease of recovery Postop analgesia Possible lower costs
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How many total vertebrae are there? How many of each?
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33 total 7 cervical 12 thoracic 5 lumbar 5 sacral 4 coccyx
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What is the sacral hiatus?
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The lamina of the last sacral vertebrae that is incomplete and bridged only by ligaments
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What structures does the needle pass through (in order) when doing a spinal anesthetic?
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Skin SQ tissue Supraspinous ligament Infraspinous ligament Ligamentum flava Epidural space Dura Subarachnoid space
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What is the name of the nerve rootlets that extend from L1 to S3?
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Caudia equina
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Where is the cervical enlargement?
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Extends from the spinal segments C4-T1
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Where is the lumbosacral enlargement?
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L2-S3
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What envelopes the spinal cord?
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The meninges (dura mater, arachnoid mater, pia mater)
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What is the name of the space that contains the CSF?
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Subarachnoid space
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What is the function of the CSF?
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Protect the spinal cord from shock injuries
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What does the epidural space contain?
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Epidural veins, fat, lymphatics, segmental arteries, and nerve roots.
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What three structures protect the epidural space as it is approached by the anesthetist's needle?
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Ligamenta flava Lamina Spinous processes
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Where is the epidural space the largest (posterior to anterior) and what is the approximate width?
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midlumbar region, 5-6 mm
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How big is the epidural space at the midline thoracic region?
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3-5 mm
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How big is the epidural space at the lower cervical region?
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1.5-2 mm
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What is scoliosis?
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Lateral curvature in the spine
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What is an excessive posterior curvature or hump in the spine called?
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Kyphosis
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What is excessive hollowing of the back called?
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Lordosis
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What is a dermatome?
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The area of cutaneous sensation supplied by a spinal nerve that is anatomically identified as it passes through an intervertebral foramen.
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How can a dermatome be tested?
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Via a scratch test to test sensation Via an alcohol pad to test temp sensation
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What type of nerve fibers are heavily myelinated and supply motor function?
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A-alpha
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What type of nerve fibers are moderately myelinated and supply touch and pressure function?
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A-beta
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What type of nerve fibers supply proprioception?
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A-gamma
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What type of nerve fibers supply pain and temperature and are lightly myelinated?
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A-delta
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What type of nerve fibers supply pain and temperature and are unmyelinated?
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C fibers
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What type of nerve fibers function as preganglionic autonomic and are lightly myelinated?
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B fibers
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What is a differential block?
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When a local anesthetic interrupts nerve transmission of autonomic nerves but not sensory or motor nerves (because of variation in susceptibility).
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How much higher can the level of sympathetic blockade be than sensory?
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As high as 6 or more.
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Why is a spinal anesthesia referred to as more "dense" than epidural anesthesia?
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Spinal anesthesia is more effective or complete from the patient's perspective.
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What can be done to make an epidural anesthetic more dense?
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Increase concentration of volume of agent Allow enough time for the drug to diffuse into the CSF or pass via redicular arteries into the spinal cord.
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Why are musculoskeletal deformities and fusion and scarring of the vertebrae considered relative contraindications of neuroaxial anesthesia?
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Location of epidural or subarachnoid spaces may be technically difficult and spread of anesthesia agents may be limited by anatomic alterations.
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What are suggested values for platelet counts, PT, and PTT to serve as thresholds for avoiding neuraxial anesthesia?
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Platelet count 2 times normal
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Are NSAIDS or aspirin contraindications for neuraxial anesthesia?
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No
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When should the first dose of LMWH be administered following epidural catheter removal?
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At least 2 hrs after removal
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How long should a catheter be removed after dosing by a LMWH?
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BID: Remove next morning after last dose Qday: Remove a minimum of 10-12 hrs after last dose.
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When can patients that have been on a heparin gtt safely receive neuraxial anesthesia?
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After a normal aPTT is obtained
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How many days preop before neuraxial anesthsia should warfarin be stopped? What should the INR value be before inserting the spinal/epidural?
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At least 4 days before INR < 1.5
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When should fibrinolytics or thrombolytic drugs stop meds in order to have a neuraxial technique?
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> 10 days after stopping
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When should ticlopine, clopidogrel be stopped before regional anesthesia?
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Ticlopidime 14 days clopidogrel: 7 days
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What are some distinct advantages to using regional anesthesia?
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Decreased N/V Decreased urinary retention Reduced total opioids Greater mental alertness Faster discharge Blunts surgical stress response Decrease interop blood loss Decreased thromboembolic events Decreased ilius Improved resp CV stability
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What specific patient groups are good for neuraxial anesthesia?
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Obstetric Urologic
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What are some risks of neuraxial anesthesia?
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Failed block High spinal N/V Allergic rxns PDPH hearing loss transient neurologic symptoms Infection Peridural abscess hematoma formation
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What will the first s/sx be of hematoma after neuraxial anesthesia?
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New onset weakness to lower limbs & sensory deficit Bowel/bladder dysfunction New onset back pain
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What is the window for effective emergent surgery for hematoma causing significant deficits?
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Less than 8 hrs
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How does infection occur with neuraxial anesthesia?
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Bacteria track into the site of injection from lack of aseptic technique
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What increases the risk of infection from neuraxial anesthesia?
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Preexisting dermatologic conditions Underlying sepsis Preexisting chronic infections (HIV or HSV)
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What population should not have neuraxial anesthesia due to intolerance of bradycardia or hypotension?
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Patients with fixed-volume cardiac states such as IHHS or severe atrial stenosis
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What effect can occur from decreased input in the RAS from neuraxial anesthesia?
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Somnolence
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What characterizes a total spinal?
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Cardiac and respiratory compromise
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What are the names of cutting needles?
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Quincke
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What are the names of noncutting needles?
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Sprotte, Whitacre
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What needle sizes are typically used for spinals?
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25-27 gauge
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What is the disadvantage of cutting needles in spinals?
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Increase risk PDPH
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What should be monitored when placing a spinal?
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BP, continuous ECG, pulse ox, VS (assess in supine and position in which the block will be administered.
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What is the name of the block that can be administered for vaginal, urologic, or rectal surgeries?
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Saddle block
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What position should the patient be in for placement of the spinal?
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side lying or sitting up; have pt arch back into a C-shape
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What is Tuffiers line (landmarks?)
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Line formed between tops of iliac crests; cosses the vertebral column as high as L3-L4 or ask low as L5-S1
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How much rapid acting local anesthetic should be used to numb the puncture site before doing the spinal?
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3-5 mL of lido
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What is the depth of the skin to the epudural space?
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2.5cm at shallowest (usu 4-5 cm, not usually more than 9 cm)
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What are the two approaches that can be used to place a spinal?
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Midline, Paramedian
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Describe the bromage grip.
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Firmly place dorsum of nondominant hand against patient's back and below spinal needle, grasp needle hub between thumb and index finger to stabilize needle.
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What structure will you hit first when using a paramedian approach?
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Ligamenta flavum
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How much CSF is produced each day?
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500 mL
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Where is CSF made?
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Choroid plexus of ventricles
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What reabsorbes CSF?
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Arachnoid graulations
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What is the typical volume of CSF in the spinal canal?
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30-80 mL
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What is the density of a substance compared with water referred to?
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Specific gravity
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What is the specific gravity of CSF?
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1.004-1.009
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What is baricity?
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Ratio specific gravity of local anesthetic solution in relation to CSF
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If baricity = 1, what type of is it?
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Isobaric
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What type of solution has a specific gravity greater than CSF?
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Hyperbaric
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What type of solution has a specific gravity less than CSF?
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Hypobaric
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What can be added to a local anesthetic to make it hypobaric?
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Sterile water
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What can be added to a local anesthetic to make it hyperbaric?
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Dextrose
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What are the main factors that affect spread of local anesthetics in CSF for spinals?
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Total dose Site of injection Baricity of drug Position of patient during/after injection
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What is the primary determinant of duration of a spinal anesthetic?
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Local anesthetic choice Total dose
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What does epi do when added to a spinal? How much should you add?
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prolongs duration Add 0.1-0.2 mL
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What does the addition of epi do to tetracaine, lidocaine, and bupivicaine (compare the effects)
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Titracaine - longest prolongation Lidocaine - less prolongation Bupivicaine - minimal prolongation
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What else beside epi can be added to a local anesthetic to prolong the spinal anesthetic?
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Opioids, alpha2-adrenergic receptor meds (clonidine)
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What is the spinal dose of tetracaine for a vaginal delivery?
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5 mg
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What is the spinal dose of tetracaine for a cesarean section?
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8 mg
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What is the spinal dose of tetracaine for a anorectal surgery?
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6 mg
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What is the spinal dose of tetracaine for a genital or lower-extremity surgery?
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6-10 mg
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What is the spinal dose of tetracaine for a hernia or pelvic procedure surgery?
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10-12 mg
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What is the spinal dose of tetracaine for a intraabdominal surgery?
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By height: 5 to 5'5": 12 mg 5'6" to 6: 15 mg >6: 18 mg
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What is the spinal dose of tetracaine for a back or spine surgery?
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10-15 mg
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What is the spinal dose of bupivicaine for a genital or lower-extremity surgery?
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8-12 mg
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What is the spinal dose of bupivicaine for a vaginal delivery surgery?
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5-7 mg
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What is the spinal dose of bupivicaine for a cesarean section surgery?
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10 mg
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What is the spinal dose of bupivicaine for a anorectal surgery?
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8 mg
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What is the spinal dose of bupivicaine for a hernia/pelvic procedure surgery?
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12-15 mg
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What is the spinal dose of bupivicaine for a intraabdominal surgery?
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By height: 5 to 5'5": 15 mg 5'6" to 6: 18 mg >6: 20 mg
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What is the spinal dose of bupivicaine for a back and spine surgery?
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15-20 mg
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What is the spinal dose of lidocaine for a intraabdominal surgery?
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Not used
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What is the spinal dose of lidocaine for a back and spine surgery?
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Not used
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What is the spinal dose of lidocaine for a hernia or pelvic procedure surgery?
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100 mg
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What is the spinal dose of lidocaine for a genital or lower-extremity surgery?
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75-100 mg
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What is the spinal dose of lidocaine for a anorectal surgery?
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8 mg
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What is the spinal dose of lidocaine for a cesarean section surgery?
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50-75 mg
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What is the spinal dose of lidocaine for a vaginal delivery?
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25 mg
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What is the duration of tetracaine without epi?
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~1-1.5 hrs
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What is the duration of tetracaine with epi?
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~2-3 hrs
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What is the duration of bupivicaine without epi?
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~1-1.5 hrs
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What is the duration of bupivicaine with epi?
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~1.5-2 hrs
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What is the duration of lidocaine without epi?
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~15-60 min
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What is the duration of lidocaine with epi?
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~45 min to 1.5 hrs
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If using an epidural catheter into the subarachnoid space how far should the catheter be inserted into the subarachnoid space?
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2-3 cm
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What is caudia equina syndrome?
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Persistent paralysis of the nerves of the cauda equina with resultant lower extremity weakness and bowel and bladder dysfunction due to neurotoxic concentrations of hyperbaric local anesthetics.
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What is transient neurologic symptoms (TNS)?
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Pain originating in the gluteal region that radiates to both lower extremities. Symptoms appear a few hours up to 24 hrs after recover and spontaneously disappear in virtually all cases in 10 days. Symptoms grande from mild to severe radicular back pain.
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How is TNS treated?
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NSAIDS, occasionally opioids.
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What LA is TNS associated primarily with?
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Lido
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Besides lido, what are contributing factors to TNS?
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Knee and hip flexion (stretching nerve roots) Obesity Ambulatory surgery
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What is the mechanism of a differential block?
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As the local anesthetic spreads rostrally and the concentration gradient lessens, only the most susceptible neurons will be blocked and a differential block occurs.
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How many segments higher than sensory fibers are sympathetic fibers typically blocked (mean)?
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6-7 segments higher
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What are the CV results of SNS blockade?
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Arterial vasodilation Decreased systemic vascular resistance venous pooling Reduction of venous return
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At what level are the cardiac accelerators?
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T1-T4
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What has been implicated in the increase in severity of perioperative hypotension?
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Rapid position changes Changes in skeletal m. Decreased venous return Low preop volume Reflex surgical stim preop meds PE pregnancy systemic rxn to medications
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How much of a decrease in baseline BP is usual from spinal anesthesia?
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20%
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What are some measures that can be used to prevent hypotension?
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Give fluids 15 min before (15mL/kg)
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What is the drug of choice to give in patients with symptomatic bradycardia form neuraxial anesthesia?
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Ephedrine (5-10 mg IV boluses) if HR low Phenylephrine 50-100 mcg if high HR Atropine 0.4-0.8 mg bradycardia Give fluids
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What can cause ventilatory difficulty for spinal anesthesia recipients?
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Accessory/abdominal/intercostal muscle impairment Ability to cough and clear secretions is inhibited
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What will happen with a high spinal with respect to the GI tract?
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Sympathectomy -- unopposed parasympathetic activity.
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What spinal roots are associated with the GI tract?
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T5-L2
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What can be a problem with abdominal surgery and neuraxial anesthesia?
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Increased bowel motility and less muscle relaxation can cause wound breakdown
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Why are N/V associated with neuraxial anesthesia?
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GI hyperperistalis, HYPOTENSION, hypoxemia, opioids.
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What s/sx are associated with the surgical stress response?
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Increases in blood adrenocorticotropins, cortisol, insulin, growth hormone, aldosterone, and glucose leads to tachycardia, hypertension, catabolism, immunosuppression and hypercoagulability.
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What causes PDPH?
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A puncture in the dura causes leaking of CSF; medulla, brainstem lose hydraulic support and drop into the foramen magnum, stretch meninges and pull on the tentorium --> headache.
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What are risk factors that cause an increase in PDPH
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Cutting needles Multiple punctures Female patients Young Pregnancy History of PDPH
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When do PDPH headaches usually occur?
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Several hours to first or second post-op day.
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What are the symptoms of a PDPH?
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Mild to incapacitating bilateral frontal HA that radiates from behind the eyes and across the head toward the occiput and often into the neck and shoulders. It is a postural headache.
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What are other symptoms of PDPH besides HA?
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n/V appetite loss blurred vision photophobia senstion of plugging of the ears loss of hearing tinnitus vertigo depression
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What is conservative management of PDPH?
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Horizontal position adequate hydration oral analgesics caffeine (500 mg IV) or 300 mg PO
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What is the definitive treatment for PDPH?
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Epidural blood patch
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Where is the needle inserted when doing an epidural blood patch?
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at or above level of lowest initial needle insertion
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How much blood is injected with an epidural blood patch and where does it come from?
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Draw 20 mL from patient Inject 12-15 mL
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What should be done after the epidural blood patch is done?
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Pt should be supine for 1/2 to 1 hr
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If a blood patch fails what should be done?
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A repeat patch can be attempted in 24 hrs
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What are some risks of epidural blood patch?
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Backache-treat with antispasmotics and NSAIDS
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What does nausea immediately after spinal insertion indicate?
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Significant hypotension, high spinal. Treat with fluids and sympathomimetics (unopposed PSN activity)
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What should be done to avoid hypotension from neuraxial blocks?
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Adequate hydration O2
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What dose of Fent and Sufent can be added to a spinal to decrease n/v?
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2.5-5 mcg Sufent 20 mcg Fent
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Why do patients get urinary retention from neuraxial anesthesia?
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Unopposed PSN causes increased tone to internal urethral sphincter
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What are some causes for neurologic deficits following neuraxial anesthesia?
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Direct needle injury Drug related neurotoxicity Anterior spinal artery syndrome Undiagnosed neurologic sidease Intraneural or intramedullary injections Presence of blood in CSF Hematomas Absesses
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What is the timeframe that sudden cardiac arrest can occur with spinal anesthesia?
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20-60 min after onset of spinal block
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What events are frequently associated with sudden cardiac arrest with spinal anesthesia?
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Sign. blood loss Orthopedic cement placement
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What are signs and symptoms of impending cardiac arrest with spinal anesthesia?
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Gradual downward trend in HR then abrupt severe bradycardia or asystole. Or bradycardia/asystole in seconds or minutes from a stable HR
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What are some proposed mechanisms for sudden cardiac arrest in regional anesthesia?
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Benzold Jarish reflex Low pressure right atrial baroreceptors Activation of receptors within myocardial pacemaker cells. High sympathetic level, sedation, hypoxemia, and hypercarbia.
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What are some auditory, ocular, and facial complications of spinals?
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Transient hypoacusis or hearing loss retinal hemmorrhage Horner syndrome (ptosis, miosis, anhidrosis, enphthamosis) Most are self-limiting
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What is the main advantages to epidurals over spinals?
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Can be used for long duration Post-op pain Can be converted from pain relief to surgical dosing for cesarians. Good for labor pain.
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Why are epidural volumes so much bigger than spinal volumes?
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Epidural space is much larger. Medication must diffuse into CSF
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What is the order of structures that you will pass thru when performing an epidural?
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Skin SQ tissue Supraspinous ligament Infraspinous ligament Ligamentum Flava
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What type of needle is typically used to place an epidural and what characteristics does it have?
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Tuohy Blunt tip Curved tip (30 degrees) 16-18 gauge (epidural catheter diameter is 2 gauges smaller than needle diameter) Others are: Hustead needle and Crawford needle
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How far should the epidural catheter be threaded into the epidural space?
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3-5 cm
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What is the name of the hand grip that should be used with epidural insertion?
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Bromage grip
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How do you know when the Tuohy catheter is in the epidural space?
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You will lose resistance
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How can you determine if you are in the epidural space?
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Insert air through the catheter and palpate the spinous process. If you feel creptus the needle is in the adjacent tissues.
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What may be felt by the patient as the epidural catheter is threaded into the epidural space?
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Funny bone sensation down one or both legs (paresthesia) - may indicate that catheter has brushed by a nerve root. If it persists, wWithdraw the catheter and replace. Best to move to another level.
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What can happen if you inject epidural medication into a patient complaining of persistent paresthesias?
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nerve root damage nerve-root death long-term morbidities
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When removing the epidural catheter how should this NOT be done?
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Never through the needle! (catheter shear and embed foreign material in patient's back)
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If aspiration of the epidural catheter returns CSF or blood what should be done?
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It should be removed and replaced at a different interspace?
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What is the purpose of the epidural test dose?
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To determine if the catheter or needle has inadvertently entered the subarachnoid space or an epidural vein.
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What is the epidural test dose (meds?):
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45 mg Lido (1.5%) 15 mcg Epi (1:200,000) total 3 mL
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What will you see if the epidural is in the subarachnoid space?
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Spinal anesthesia in 3 minutes (determined by the Lido)
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What will you see if the epidural is in the epidural vein?
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20% rise in HR and BP within 30 seconds (determined by the Epi); tinnitus, metallic taste, circumoral numbness (determined by the Lido)
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What else could be used as a test dose for an epidural catheter besides lido/edi?
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100 mcg undiluted Fent (pt will experience immediate dizziness/sleepiness from opioid)
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What will be the first structure you feel if inserting an epidural using the paramedian approach?
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Ligamentum flava
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What are the two most important factors in determining the extent of epidural blockade?
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Dose and site of injection
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If inserting epidural at the cervical or thoracic space what must be done to the dosing?
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Decrease volume - spaces are much smaller
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What spinal level (where would it be inserted) is used to provide blockade for an epidural for upper abdominal surgery?
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T8-T10
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What spinal level (where would it be inserted) is used to provide blockade for an epidural for labor or lower abdominal surgery?
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L2-L3
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What spinal level (where would it be inserted) is used to provide blockade for an epidural for thoracic surgery?
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T4-T5
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What spinal level (where would it be inserted) is used to provide blockade for an epidural for chronic pain treatments or surgery ot the arms, shoulders, or upper chest?
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C7 to T1
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What is the definition of dose for epidural medications?
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Volume x concentration
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What determines the density of the block for epidurals?
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concentration of LA
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What determines the spread of the LA for epidurals?
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Volume
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How much volume per segment should be used for epidurals for cervical, thoracic, and lumbar?
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Cervical & thoracic: 0.7 - 1 mL per segment (<10mL) Lumbar: 1.25 - 1.5 mL per segment (15-20 mL)
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Which direction will the spread of epidural anesthesia be faster?
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Cephalad
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What are other factors that affect level of blockade achieved with epidural anesthesia?
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Height weight age patient position during injection pregnancy speed/mode of injection
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Why should drugs be injected slowly into the epidural space?
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Avoid rapid increased in CSF pressure, HA, increased ICP
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What will be different about the spread of epidural anesthesia in the elderly?
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May be 3 or 4 dermatomes greater (age related tissue differences - less compliant and less leaky epidural space
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What volume per lumbar level should be used for elderly and pregnant patients?
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0.5-1 mL / segment
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What should be the position of the epidural catheter and dose for procedures of the chest?
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T12-L2; 8-12 mL
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What should be the position of the epidural catheter and dose for procedures of the upper abdomen?
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L2; 12-16 mL (7-10 mL for incisional pain)
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What should be the position of the epidural catheter and dose for procedures of the lower abdomen?
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L2-L3; 8-16 mL (depending on desired level)
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What should be the position of the epidural catheter and dose for procedures of the lower extremity?
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L4 (anesthesia); 10-14 mL L2 (sympathetic block); 5-7 mL
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What should be the position of the epidural catheter and dose for procedures of the perineium?
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L4; 8-12 mL
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What should be the position of the epidural catheter and dose for procedures of the back and flank?
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L2; 10-14 mL
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What should be the position of the epidural catheter and dose for procedures of the vaginal delivery?
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L3 (first stage labor: 5-7 mL) L3 (2nd and 3rd stage labor: 10-12 mL)
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What increments should epidural meds be injected in?
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3-5 mL every 3 minutes
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What two factors determine penetration of opioids from the epidural space to the subarachnoid space?
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Lipid solubility Molecular weight
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Where are the opioid receptors located in the spinal cord?
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Substantia Gelantinosa
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How much is the opioid dose increased when giving via epidural versus intrathecally?
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10 times more
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What opioid cannot be given with a LA via epidural?
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DepoDur (extended release morphine)
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What is the time to maximal spread for epidural anesthetics?
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10-25 min
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Why is it important to consisently check dermatome levels when maintaining an epidural anesthetic?
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Tachyphylaxis can occur if regression of level of blockade is allowed beyond two dermatome segments (more likely to occur with short-acting amides like lido or mepivacaine)
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What and be done to deal with a one-sided or single sensory block?
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Repositioning the patient with the unblocked side down or administer more local anesthetic.
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What are some complications of epidural anesthesia?
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High level of blockade (decreased BP, CO, SV, HR, PVR) Backache PDPH (wet tap?) Neuraxial anesthesia complications (spine ache, root pain, weakness, bowel or bladder dysfunction
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Why is combined spinal/epidural anesthesia used (advantage0?
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Quicker onset of spinal with flexibility of epidural
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What is the two level technique for combined neuraxial anesthesia?
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Epidural inserted first, spinal needle inserted second, placed one or two interspaces lower
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What are some potential problems with the two level technique of neuraxial anesthesia?
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Inability to determine test dose from spinal block Inability to differentiate the epidural test dose from CSF. Epidural catheter laceration by the spinal needle. Misdirection of the spinal needle by the catheter. Inability to obtain CSF becasue of compression of the dural sac by the test dose. Increased risk of dural puncture by the epidural catheter.
question
What are some potential disadvantages with the two level technique of neuraxial anesthesia?
answer
Increased discomfort, tissue trauma, morbidiy with multilevel puncture.
question
What is the single level technique for spinal/epidural combined anesthesia?
answer
Insertion of an epidural needle at the appropriate interspace and then using the epidural needlea s a guide for the spinal needle.
question
What are disadvantages to the single level technique for spinal/epidural combined anesthesia?
answer
Possible inadequate spinal block if catheter placement is delayed, potential for nerve root trauma, inability to reliably test the catheter with a preexisting spinal block.
