Regional anesthesia Barry University Central Blocks – Flashcards
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What are central blocks also known as?
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Neuroaxial Blocks
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What bad side effects are decreased when using a central block?
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Lungs: Less DVT, PE, Bleeding, pneumonia/resp depression Heart: Less incidence of Cardiac complications less vascular graft occlusions Less cardiac stress response and because of the sympathetctomy nature of central blocks, less sympathetic stimulation of the heart. GI: less PONV, earlier return of GI motility PAIN: Less opioids needed
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What are the absolute/controversial contraindications for Central Blocks?
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Patient REFUSAL INFECTION at site of puncture Hypovolemic shock (Severe hemorrhage) Severe idiopathic coagulopathy Increased ICP Indeterminate neurologic disease AORTIC STENOSIS.
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What are RELATIVE contraindications for central blocks?
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Pre-existing neuropathies Pre-existing Spinal injury Medical anticoagulation Heart valve diagnosis (minus aortic stenosis) Dementia Demyelination
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Which anticoagulant is NOT contraindicated?
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NSAIDS
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What should you hold for 12 hours before and 2 hours after catheter removal?
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Low molecular weight Heparin
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In what instance should you hold LMWH for 24 hours and Heparin for 2 hours after a central block?
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if you puncture an epidural vein.
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What are the Glycoprotein IIa and IIIb inhibitors?
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Reopro, integrelin, aggrastat
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How long should you hold the Gp IIa and IIIb inhibitors post epidural?
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4 weeks post epidural.
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How many days pre-op should you hold clopidogrel? How many days pre-op should you hold ticlodipine?
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7 days 14 days
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How many vertebrae are there? How many cervical vertebrae? How many coccygeal vertebrae? How many paired spinal nerves? How many cervical spinal nerves? How many sacral spinal nerves? How many coccygeal spinal nerves?
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-33 -7 -4 -31 -8 -5 -1
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What are the two ventrally convexing regions of the spine? What are the dorsally convexing regions? What is the LOWEST point of the spine supine? What is the highest point of the spine supine?
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-Cervical;lumbar -thoracic; sacral -Lowest T5-T6 -Highest L3
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How long is the vertebral column? How long is the spine?
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-26-27 inches 17-18 inches
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Where is the Atlas located? Where is the axis located? What is another name for the cervicothoracic junction? How are the Thoracic vertebrae matched with? What vertebrae corresponds with the bottom border of the scapulae? What vertebrae corresponds with the iliac crests?
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C1 C2 C7- the most prominent structure at base of neck The corresponding ribs C7 L4-L5
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What area of the spine should NEVER be motor blocked and is reserved for analgesia (opioids and and low conc LA) only?
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Thoracic
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T/F the vertebrae have completely different structures from level to level.
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False "structurally similar level to level"
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What is also known as the structural base of the vertebra? What are attached directly to the vertebral body DORSALLY? What structure joined the pedicules to form the and oval space: vertebral FORAMEN? What is the purpose of the vertebral FORAMEN? Then, what is the purpose of the intervetebral foramen? What arises between the laminae and marks the midline of the spine's surface? What is the junction of the lamina and pedicule?
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>Vertebral body >Paired pedicules >Laminae >To house the spinal cord >to house the spinal nerves and allow it to exit. >Midline Spinous process >Transverse spinous process
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Of all the ligaments, which one is most posterior? Which ligament is the second one you go through PA? Which ligament is the posterior limit of the epidural space? What does the ligamentum flavum extend from and end at? What two structures connect the vertebral bodies and intervertebral disks?
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>Supraspinous ligament >Interspinous ligament >Ligamentum flavum >Extends from the foramen magnum to the sacral hiatus >Posterior and anterior longitudinal ligaments.
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What highly lipid sol LA clings to the posterior and lateral spaces of the epidural area?
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Etidocaine
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Where is the potential space in an epidural? How far does the epidural space extend? Where do the nerve roots exit from? What does the epidural space contain? T/F the epidural space contains many arteries. What is the name of the mess of veins in the epidural space? T/F the veins in the epidural space have valves.
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Between the Ligamentum flavum and the dura mater. >from foramen magnum to the sacral hiatus >from the intervertebral foramen to peripheral locations >contains fat, lymphatics, large network of veins >FALSE. No arteries. >Batson's plexus >False. Veins in the epidural space do NOT have valves.
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Is the epidural space discontinuous or continuous?
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It is a discontinuous space that becomes continuous when air/fluid is injected.
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What layer is being described: Delicate, nonvascular layer, closely attached to the dura mater? Also: Sub area contains roots and rootlets?
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Arachnoid mater
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What layer is the tough, outermost layer that fuses with the filum terminale and ends at S2?
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Dura Mater
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T/F we use the sub-dural space for many things clinically.
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False. Not Clinically useful.- not a good block if catheter accidentally travels here. Spotty.
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How is he pia mater described?
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Highly vascular ENDS at filum terminale. Anchors the cord to the sacrum
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Where is the CSF located?
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Subarachnoid. Between the pia mater and the arachnoid mater.
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What angle do you insert a cervial or lumbar needle?
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Horizontal
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How do you insert a thoracic needle and/or sacral needle?
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Cephalad
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Which region of the spine has widest spinal canal and smallest vertebrae body?
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The cervical spine.
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T/F the vertebrae are fused together in the sacrum.
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True.
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What is described as a defect in the roof of the dorsal aspect of the caudal end?
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Sacral hiatus.
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What part of the spine has no anesthetic significance and represents fusion of three or four rudimentary vertebrae?
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Coccyx
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How far down does the spinal cord extend in a newborn? Where does the conus medullar is end in adults?
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L3 L1
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What is another name for the end of the spinal cord?
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Conus medullaris
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How many pairs of nerve roots are there?
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31
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What are the pain paths? What are the motor paths?
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The posterior (dorsal) roots The anterior (ventral) paths
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T/F each nerve root is composed of many rootlets.
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True
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What is a cord segment?
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The area that a group of rootlets comes out to forma single spinal nerve
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What is the area of skin the spinal nerve and cord segment innervate?
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dermatomes
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What is a dermatome named for?
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The intervertebral foramen through which it runs.
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Where does the cauda equina begin? Where are lumbar punctures usually performed below?
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Below L1 Below L2
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Which 2 arteries are responsive for 25% of all blood supply to the cord? What 1 artery is responsible for 75% of all blood supply to the cord?
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>Posterior. >1 anterior
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Where do the 2 posterior arteries receive their blood supply?
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Primarily from cerebral arterial system and many collaterals. Segmental arterial injury is unlikely because of so many collaterals.
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Where does 75% the arterial supply of the spinal cord come from?
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ANTERIOR ARTERY Made up of many radicular arteries supply the anterior portion of the spine. 1. Vertebral artery 2. Cervical radicular artery 3. thoracic radicular artery 4. Radicularis Magna (artery of adamkiewicz: T8-T12) 5.Iliac artery
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T/F the artery of adamkiewicz is typically unilateral and most often lies on the left side.
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True
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How does blocking of sensation dissipate?
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Cephalad to caudal
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If you are injecting LA into subarachnoid space, where is the LA taken up?
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Into the nerve roots and spinal cord.
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What kind of spinal solution and position would be appropriate for abdomen and C section? What kinda of spinal solution and position would be appropriate for Hip/TURP/Hernia/Pelvic/appy? What kind of solution would be appropriate for lower extremities?
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-T4-T6: Hyperbaric, horizontal -T6- T8: hyperbaric/ horizontal -T10 - Isobaric solution
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What kind of solution would you use for L1-L2 perianal and perineal surgeries?
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Hyperbaric/sitting Hypobaric/jacknife Iso/ horizontal
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What are the 5 indications for spinal?
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Lower extremities, hips, perineum, lower abdomen, lumbar spine.
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Is it a usual procedure to do a t5-t7 block for a turn/chole gastric resection?
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No. It is not tolerated well because of respiratory difficulty and high sympathectomy. Risks outweigh the benefits.
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Can you do spinals for Turp? What is the level typically? What electrolyte do you have to be able to be warned about with the patient's CNS? What does shoulder pain represent during a TURP?
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>yes >T6-T8 >Hypervolemia and hyponateremia >Represents secondary pain from peritoneal stimulation or bladder perforation.
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What needle is cutting needle and are usually 22G>
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Quincke-babcock
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What needles have a pencil point rounded bevel and are typically 24G? T/F these needles have a better "feel" and need more force to enter space.
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Whitacre, Sprotte, Marx
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How are the needles measured?
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Outside diameter.
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How would you position the patient for spinal?
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Sitting position, back arched like a mad cat, causes interspace to open. Lateral decubitus, hips and knees maximally flexed. "cannonball" "fetal" Jacknife/prone
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Where is the affected side for broken hips in a lateral decubitus position?
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Down
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What position may CSF have to be aspirated?
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Jacknife
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T/F pt should have absolutely NO sedation on board for a spinal block.
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False. Lite sedation is OK
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How should you localize the area for needle injection?
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Skin wheal then do 2 in deeper fanning out local lidocaine for subq tissues.
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What kind of angle is used for midline spinal approach? When is an increase in resistance felt? What produces the "pop"? What is the characteristic of a successful spinal? When you remove the stylet, what should you see to confirm? What should you do if the patient feels ANY parasthesia? T/F it is OK to keep injecting if you see heme.
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>Slightly cephalic >when the introducer enters the interspinous ligament. >The dura produces the POP >A successful spinal is smooth passage. >you should see CSF. >stop and reposition needle. >False. Do not inject.
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What do you bypass with the paramedian approach? What population is the paramedian approach useful in? Where do you move once you've found the lower border of the interspace? What is the first ligament encountered using the paramedian approach? What can repeated contact with the periosteum cause?
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You bypass the supraspinous ligament and the interspinous ligament. >Elderly, calcified interspinous ligament, difficulty flexing spine. >1 cm lateral. >Ligamentum Flavum >pain
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What is baracity?
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Density of local anesthetic/ density of CSF
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What four local anesthetic properties determine the spread of anesthetic in subarachnoid space?
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Baracity, dose, volume, concentration (can contribute to baracity.)
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What four physical properties influence anesthetic spread?
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Height extremes physiologic status spinal column anatomy decreased CSF volume
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What are the numbers corresponding to baracity?
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1=Isobaric 1.0015= hyperbaric
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What can you use for a T10 spinal block? T4 spinal block?
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T10: Bupivicaine 0.75% 8-12mg Lidocaine 5.0% 50-75mg. T4: Bupivicaine 0.75% 14-20mg Lidocaine 5.0% 75-100mg
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What are the dermatomal levels corresponding to these common surgical procedures ? Upper abdominal surgery uterine, intestinal, urologic TURP Hip, vaginal delivery Thigh/ Lower Leg Foot/ankle perineal and anal surgery
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T4 T6 T10 T10 L1 L2 S2-S5
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What is the CSF made out of?
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99% water
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How much CSF is there? How much is replaced per hour? What is the other 1% of CSF made out of? Where is the the CSF made? How is CSF removed?
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100-160mL 20-25mL/hr Protein, electrolytes, glucose, NT, metabolites CHoroid plexus Arachnoid Villi
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What is the Specific gravity of CSF?
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1.003-1.008
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What is the most widely used baracity?
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Hyperbaric
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What maneuver can protect cervical spread of hyperbaric soon somewhat?
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Neck flexion
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What are the three medicines that can all be mixed with CSF?
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Tetracaine, lidocaine, bupivacaine LOWERS the concentration making it lighter and ISO baric
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What does intra-abdominal pressure affect with the level of local injected?
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It affects the final level of local injected and causes changes in the contour of the subarachnoid space and goal volume of CSF.
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What are examples of increased IAP?
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Ascites, obesity, tumores, pregnancy cause decreases in venous return and back flow into epidural veins. Large epidural veins occupy the space.
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What can venous back flow into the epidural space cause the LA to proximal vs distal?
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Proximal
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What can the uterus cause in the epidural space? What can this cause?
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an increased volume in the venous plexus (Batson's plexus) > a smaller tighter epidural and subarachnoid space. >higher spread.
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What length of needle do you need in an obese patient? What approach is more difficult in an obese patient?
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>4-6" >paramedian approach
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What can scoliosis cause difficulties in?
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Hard to identify midline and decrease CSF volume.
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What is thought to happen with increasing age?
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Spinal and epidural spaces are thought to become smaller and less compliant. Stenosis and scarring and calcification of tissues. Decrease your doses.
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Where does the sympathetic chain originate from? T/F only arterial dilation occur in a sympathectomy.
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The thoracolumbar spinal cord. FALSE. Venodilation also occurs.
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What is the primary reason for hypotension seen in spinal anesthesia? Is arterial vasodilation maximal?
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Loss of venous tone and loss of venous return (preload) No. The arteries retain autonomic tone after sympathetic denervation.
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What is a total sympathectomy?
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Increase in volume of capacitance vessels and decrease in venous return to the heart. Hypotension.
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What is a partial sympathectomy?
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T8 block usually allows physiologic compensation with vasoconstriction mediated by sympathetic fibers above the block.
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Where are the cardiac accelerator fibers?
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T1-T4 (sympathetic efferents) Increase HR when stimulated. High central blockade and unopposed vagal activity leads to bradycardia.
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How are the pulmonary function affected primarily?
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Through motor blockage of intercostal muscles and abdominal muscles.
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How high would you have to block if you suspected a phrenic nerve block?
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C3-C5 COncentration is typically not enough to fully block Alpha nerves.
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What is spinal block apnea typically attributed to?
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Hypoperfusion of the brainstem respiratory centers.
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How is renal blood flow maintained throughout sympathectomy?
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Autoregulation
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What happens to urinary muscle with a spinal? Why is it the last to resolve?
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Tone is eliminated and bladder retention is common. Last to resolve r/t it being S3-S4 block.
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Why do patients experience N/V?
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Unopposed parasympathetic activity and hypotension.
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What can sympathetic activation of pain cause in the body?
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Hormonal and metabolic responses.
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What can regional anesthesia block metabolically?
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Myocardial stress, hyperglycemia, and natural hypertension.
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What are the complications of a spinal?
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Pain with injection Backache Headache Urinary Retention Meningitis Vascular Injury Nerve Injury (cauda equina syndrome; TNS) High Spinal.
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What can needle insertion cause?
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Hyperemia, local tissue irritation, replex spasm of muscles, Soreness can last for 10-14 days.
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What can cause the PDPH?
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During a spinal, there is a natural loss in CSF that causes a downward traction on the structures of the CNS.
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When does the headache start typically?
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6-12 hours after the epidural
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What is the most important factor for PDPH? T/F Transecting the fibers is better than going in-between them with a parallel bevel.
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>needle size >False. Go parallel.
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What are the things that treat PDPH?
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FLuids/hydration oral analgesics Abd binder caffeine Bedrest/supine
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What is an epidural blood patch?
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Placement of epidural needle in the area of the lumbar puncture. 12-20mL of pt's blood obtained during venipuncture (sterile) is injected in the epidural space. (95% of pts have complete relief after 24hr and 99% have relief after 2nd patch.)
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What is urinary retention associated with blockage of? What gender is UR more common in? What can cause neurogenic bladder? What can bladder distention cause?
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>S2-S4 >Males >long cases w/no foley >HTN and tachycardia.
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What are some of the causes of meningitis?
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Back in the day when needles were reused and cleansed with caustic substances. >can be a problem if betadine is not removed from the back before dural puncture.
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What can cause an epidural hematoma? When should you investigate a bleed? What is the best thing for a vascular injury resolving? What are the two tests you can do do diagnose a bleed? What is the emergency maneuver you have to perform for a vascular injury?
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>bleeding from an epidural venous plexus >when the anesthetic prolongs beyond a reasonable amount of time or begins to build up again after wearing off >early diagnosis is the best thing >CT MRI >decompressive laminectomy
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How frequent is a nerve injury in a spinal? What are the causes of these injuries? What levels should prevent contact with the spinal cord?
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>1:10,000 >Direct contact with Cauda equina >Below L2.
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What is TNS? How is it caused?
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A painful condition of the buttocks and thighs with possible radiation to the lower extermities, beginning as soon as a few hours after spinal anesthesia and lasting as long as ten days. >caused by all LA but more by Mep and Lido
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What are the symptoms of High Spinal Anesthesia?
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>severe hypotension > profound bradycardia ( Blocked cardioaccelerators T1-T4) >respiratory insufficiency >Hypoperfusion to medulla
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What are the causes of High spinal?
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Position High total dose Position Baricity Sudden increases in intra abdominal pressure (valsalva's maneuver, coughing, lifting of the legs.
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How do you treat a high spinal?
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Support airway and increase circulation ventilate with 100@ Intubate if needed Fluids pressors Do not put head up. Give ephedrine May need a touch of epinephrine
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How does the epidural create anesthesia?
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The LA diffuses through the intervertebral foramen to nerve roots and through the meninges to CSF.
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In comparison to spinals what do the epidurals require more of? T/F Epidurals can provide analgesia with minimal block or full motor block.
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Epidurals require more volume/time True.
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How is the epidural space bounded? Where is the widest part of the epidural space? What is the epidural space filled with?
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Dural layer ventrally and ligamentum flavum dorsally. L2 loose connective tissue that surrounds the epidural veins (Venus plexus)
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What can venous obstruction cause in the epidural space? T/F it is OK to thread the catheter during a contraction. What are the hardest nerves to anesthetize?
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Engorgement of the azygos system False. Do not thread during contraction. L5-S1
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How much do you have to increase the dose of LA to fill the potential space? Why is onset for epidurals slower? What is segmental anesthesia?
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>10X the dose >Because it has to diffuse across the membranes. >the epidural medicine extends upward and downward from the injection point.
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What does the segmental spread depend on?
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Largely on the volume of the local. Example: 5mL may produce a narrow band of 3-5 dermatomes whole 20mL will produce anesthesia from upper thoracic area to sacrum.
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What is the epidural placement technique?
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>Advance Toughy needle midline until resistance is felt. >Attach glass syringe with 3-4mL of air/fluid >when barrel of syringe is tapped it should be firm >Advance slowly tapping syringe intermittently >ligamentum Flavum is crunchy >after passes through LF will feel 'give" >LOR will be felt >remove syringe-inject saline >hold needle in place while catheter is threaded. >Remove needle.
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What is the test dose for an Epidural?
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3mL 45mg of 1.5% lidocaine 5 micrograms of 1:200,000 Epinephrine
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What will the patient feel with an intravascular injection?
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>HR increase of 20% within 30-60seconds >circumoral numbness, ringing in ears
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What will the patient feel if it is a subarachnoid injection accidentally?
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Produces spinal anesthesia within 3 minutes.
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What two instances will it be hard to see the increase in HR with the test dose?
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When opioids are used during pregnancy contractions
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What is the technique after a negative test dose is injected?
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Continuous epidural infusion or 5mL q 3-5 mins until desired effect
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T/F if you have already aspirated negative, it is not necessary to aspirate again for re-dosing.
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FALSE. MUST aspirate every time you re-dose.
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What is the simple dosing rule?
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1-2mL of anesthetic for each spinal segment to be anesthetized.
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What happens if you wet-tap a patient with a Toughy needle?
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Lose LOTS of CSF
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Epidural: The _____ of LA is a function of the _______ and the _____ of the solution.
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DOSE VOLUME CONCENTRATION Ex: The higher the volume of a lower concentration, will result in a higher sensory level with less motor block. 2. A lower volume of a higher concentration will result in a lower but denser sensory and motor block (more surgical).
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EPIDURAL: What is the consideration for patient age and dose changes? What is the consideration for weight and spread? T/F you don't need to change your dose for <5ft tall. T/F Position of the patient has minimal effect. Is it easier/harder to block L5-S1 in sitting position?
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> decrease dose >obesity will spread the LA cephalic >less than 5 ft tall decrease dose to maybe 1cc per segment >true >harder to block in sitting
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What is a wet-tap? What is the occurrence of headache in a wet-tap? What are the signs of meningitis? What is the protocol when you wet-tap?
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>accidentally go through dura with the toughy needle (17G) >40-80% >Nuchal rigidity, fever, chills >make sure there is a policy. Give dose as if spinal.
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What are the many benefits of neuroaxial opioids?
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>modulate alpha delta and C fibers. >improve preoperative analgesia >synergistic >reduce supra spinal effects of systemic opioids.
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T/F there aren't any opioid receptors in the spinal cord.
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False. there are opioid receptors present in the spinal cord.
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How long can a morphine epidural stay in? Is epidural morphine water or lipid soluble? What is a serious side effect to look for with morphine epidural?
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>12-24 hours >Water soluble >delayed respiratory depression 6-12 hours post injection.
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Is the fentanyl epidural lipid soluble or water soluble? Will you see a more immediate effect with fentanyl or morphine? What does fentanyl decrease the need for? Where is fentanyl absorbed? What is a serious side effect of fentanyl?
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>Lipid soluble >more immediate with fentanyl > decreases the need for other opioids for volatiles. >rootlets, vascular system, cord. >early respiratory depression
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What is the length of a spinal morphine block? Is morphine useful for intraoperative relief? Why or why not? What should you tell the ICU nurses if you give morphine as a spinal?
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6-18 hours >not useful for intraoperative relief because it is hydrophilic nature >Tell them to not use opioid breakthrough because of the late onset reap depression
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What spinal opioid has quicker uptake? What is an appropriate dose for Fentanyl spinal? How much can you give safely to a pregnant individual?
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>fentanyl is quicker *10-25mcg >Little respiratory depression, is seen early *16mcg for parturients.
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What is the most common regional in pediatrics?
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Caudal epidural
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T/F you do not have to provide anesthesia to the patient receiving a caudal block/
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False. you may put this child asleep
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What is this surgery usually used for?
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surgeries of the perineum and lower abdomen.
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Where is the sacral cornua located? Where is the sacral hiatus located? Is it always necessary to do a wheal? What size needle is used? What angle is the needle placed? What ligament is punctured and produces a pop?
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>just above the gluteal crease >in-between the sacral cornua. 5cm above the coccyx. >not always necessary >22g normal IV catheter or Jelco needle. >70 degrees >saccrococcygeal ligament
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Caudal Epidural What should you drop your angle to once you have crossed the sacrococcygeal ligament? How much further should you advance the needle? How can you confirm placement? What is the dosing for a caudal epidural?
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Drop the angle to 45 degrees >Advance inject some air >1cc/kg of low concentration bupivacaine (0.175-0.25%)
