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Spinal Anesthesia
| Question | Answer |
|---|---|
| There are ____ cervical vertebrae. | Seven |
| There are _____ thoracic vertebrae. | twelve |
| There are ______ lumbar vertebrae. | five |
| There are _______ sacral vertebrae. | five |
| There are ______ coccygeal vertebrae. | four |
| The first cervical vertebrae is called the _____. | atlas |
| The second cervical vertebrae is called the ______. | axis |
| All articulate with their corresoponding rib. | thoracic vertebrae |
| There are ______ cervical nerves that exit _____ their corresponding vertebrae. | eight above |
| The spinal nerves begin exiting below their respective vertebrae begining at ______. | T1 |
| The dural sac extends to ______ in adults and to ______ in children. | S2 S3 |
| The spinal cord extends to _____ in adults and _____ in children. | L1 L3 |
| What is the principal site of action of neuraxial anesthesia? | nerve root |
| Blockade of posterior nerve roots interrupts _________. | Sensation |
| Blockade of aneterior nerve roots interrupts ____________. | Motor and autonomic function |
| Differential blockade | Sympathetic block that is two segments higher than sensory block that is two segments higher than motor block |
| Sympathetic outflow is _________. | Thoracolumbar |
| Parasympathetic outflow is _________. | Craniosacral |
| The physiologic response to neuraxial blockade results from | decreased sympathetic tone and unopposed parasympathetic tone |
| Words to use when obtaining informed consent for subarachnoid block? | Spinal anesthesia |
| Procaine spinal onset | 3-5 minutes |
| Procaine spinal duration | 50-60 min |
| CSF Specific Gravity | 1.003-1.009 at 37C |
| T10 Dermatone | Umbilicus |
| T6 Dermatone | Xiphoid |
| T4 Dermatone | Nipple line |
| Contrainidications to spinal anesthesia | Increased ICP, Septicemia, Infection at site of injection, dermatological condition, Shock or severe hypovolemia, Preexisting dx of the spinal cord, Blood clotting abnormality, Patient refusal, Lack of skill with spinal anesthesia, Length of Sx/Sx Skills |
| Relative Contraidications to spinal anesthesia | Major upper abd sx, deformities of the spine, chornic HA or backache, Blood in CSF that fails to clear, failed x 3 attempts, failure to obtain free flow CSF, minor blood clotting abnromalities |
| Most frequent complication of spinal anesthesia | Backache most likely related to the relaxation of the lordotic curve of the lumbar spine |
| Second most frequent complication of spinal anesthesia | postdural puncture headaches |
| Postdural puncture headache risk factors | young age, female sex, pregnancy, larger size of spinal needle |
| Largest interspinal space | L5-S1 |
| Reasons to not preform spinal anesthesia in elderly/"sick elderly" | Rapid hypotension & bradycardia necessitating large bolus of IVF, anticholinergics, and anticholinergics causing fluid overload, rebound hypertension, and tachycardia. |
| Reason to avoid epidural anesthesia in elderly | Spinal stenosis may create mass effect when large bolus of LA is injected into the epidural space. |
| Sacral Hiatus | five sacral vertebrae fuse into one large bone the lamina of S5 and all or part of S4 normally do not fuse leaving a caudal opening, which is more likely to be calcified in older patients. |
| Filum terminale | Extension of the pia mater, penetrates the dura and attaches the terminal end of the spinal cord to the periosteum of the coccyx |
| conus medullaris | terminal end of spinal cord |
| Blood supply to the spinal cord | Single ant spinal art from vertebral art at base of skull. Feeds ant 2/3 of cord. 2 post spinal art feed post 1/3 of cord from the post inferior cerebellar art. Radicular art in thorax/abd contribute also. Art of Adam.= major bld supply to ant lower 2/3 |
| 2 types of nerve fibers that are myelinated | A and B fibers |
| Two types of nerve fibers that carry pain trasmission | A delta and C |
| Order of nerve blockade | 1. B fibers (sympathetic preganglionic) 2. C and A delta (pain) 3. A gamma (muscle spindle) 4. A Beta (touch and pressure) 5. A alpha (motor) |
| Similarities and difference between A delta and C nerve fibers | Both transmit pain impulses but A delta fibers are myelinated and provides fast, sharp, and well localized pain sensation. C nerve fibers are not myelinated and transmit slow, poorly localized pain sensation |
| Bupivicaine spinal onset | 5-8 minutes |
| Bupivicaine spinal duration (w and w/o epi) | 90-150 min, epi may prolong by 10-30 min |
| Usual concentration of bupivicaine used for spinals | 0.75% with glucose is most commonly used and is hyperbaric. May also see 0.5% w or w/o glucose (w/o glucose is isobaric) |
| Possible dosing for bupivicaine for spinal | 8-10 mg for perineal and lower extremity block and 12-15 mg for abdominal surgery |
| Usual concentration of procaine spinal solution | 10% solution in a 2 ml vial mixed with equal volume of 10% glucose or CSF to make a 5% solution |
| Why is procaine not used as much as lidocaine? | Higher frequency of N/V, relatively high anesthetic failure, slower recovery(?) |
| Procaine spinal dosing | 50-100mg for perineal and lower extremity block, 150-200 mg for upper abd surgery. |
| How is lidocaine supplied for spinal solution | 5% solution in 7.5% glucose |
| Procaine spinal onset | 3-5 minutes |
| Procaine Spinal DOA w and w/o epi | 45 minutes plain, 60 minutes with epi |
| Lidocaine spinal onset | 3-5 minutes |
| Concerns about using lidocaine for a spinal | Linked to transient neurologic syndrome (manifests as back and leg pain). Consider limiting dose to 60-70mg and keep needle apperature pointed upwards. Reducing concentration may have no impact on incidence. Inject at a rate of no more than 0.2 ml/sec |
| Dosing of Lidocaine in spinal | 25-50 mg for perineal surgery, 75-100 mg for upper abdominal surgery |
| How is tetracaine for spinals supplied | Either as 2 ml of a 1% solution or in an ampule as 20mg of crystal |
| What is the DOA for lidocaine used in spinals plain and with epi | 60-75 min plian, 60-90 min with epi |
| What is the onset for Tetracaine in spinals? | 3-5 min |
| What is the DOA of spinal tetracaine with and without epi | 90-120 with out epi, 120-240 with epi |
| What is the dosing of tetraciane for spinal anesthesia? | 5 mg for perineal and lower extremity surgery and 15 mg for upper abd surgery |
| How can spinal tetracaine be mixed | To make hyperbaric, mix with 10% glucose, to make hypobaric mix with distilled water. |
| Adding vasoconstriction to _______ and ______ do not produce clinicallly meaningful prolongation of spinal block | lidocaine and bupivicaine |
| Most commonly used vasoconstrictors for spinal | Epinephrine or phenylephrine |
| Dosing of phenylephrine when added to spinal | 0.5-5mg (0.05-0.5 ml of 1% solution) |
| Dosing of epinephrine when added to a spinal | 02-0.5mg (0.2-0.5ml of 1:1000 solution) |
| Effects and side effects of clonidine added to a spinal | Clonidine is thought to cause hyperpolarization in the ventral horn, prolonging LA action. May cause hypotension, bradycardia, and sedation. |
| Effects and side effects of neostigmine added to a spinal | Increases ach and NO which results in analgesia. Side effects include bradycardia, hypotension, N/V, anxiety, and agitation (not commonly used) |
| Effects and side effects of narcotic added to spinal. | Acts on spinal cord opioid receptors in dorsal horn, which may improve and potentially prolong a block. Can cause N/V, itching, and respiratory depression |
| An isobaric solution injected as a spinal will not rise above ______? | T10 |
| Baricity | Ratio between density of anesthetic and density of CSF. |
| T10 Dermatone | umbilicus |
| T6 Dermatone | xiphoid process |
| T4 dermatone | Nipple line |
| Significance of tingling fingers with spinal | Block progressing to C5 C6 C7....and getting closer to the diaphragm |
| Bezold Jarisch Reflex | Arises from LV chemo or mechano receptors where hypotension leads to reflexive bradycardia to allow for improved filling of the heart. |
| When to treat spinal anesthesia associated hypotension | In an asymptomatic patient a decrease of 33% from baseline may be acceptable where as a patient with chronic HTN, perhaps a decrease by 25% is acceptable. |
| Cause of spinal mediated respiratory arrest | It is unlikely that even a high spinal would cause enough blockade of the large phrenic nerve to cause apnea. Spinal associated apnea is likely more related to decreased BP/CO causing decreased CBF and medullary ischemia resulting in apnea |
| Repiratory effects of spinal anesthesia | Even high thoracic levels do not affect TV and max insp volume as only the abd and intercostals. Max breathing capacity, expiratory volumes, and coughing will be decreased r/t intercostal and abd muscle involvement. |
| Treatment for hypotension and bradycardia r/t spinal anesthesia | Fluid, positioning, ephedrine, phenylephrine, atropine. |
| CBF during spinal anesthesia | Becomes pressure dependent for MAP less than 55mmhg but is largely unaffected otherwise |
| Hepatic blood flow during spinal | Decreased, but not significantly so |
| Renal blood flow during spinal | Decreased if MAP less than 50 but will resolve with increased BP |
| Type of spinal needles with cutting edges | Quinke Badcock, pitkin |
| Tuohy needle | noncoring huber point needle, rarely used in spinal except for introduction of catheter |
| Greene needle | rounded , non-cutting bevel |
| Sprotte Needle | Pencil point needle, which is the same as the whitacre except it has a larger opening |
| Whtitacre needle | Most commonly used spinal needle which has a pencil point, with a non-cutting bevel, and an opening on the side of the needle |
| significance of Iliac crest landmark | It is even with the spinous process of L4 with L3-L4 interspace above and L4-L5 below |
| Elimination of LA during spinal anesthesia | Elimination occurs only via uptake into vascular space. Epidural space is more vascular so will have a quicker uptake and shorter DOA compared to SAB. More highly lipid soluble drugs will have a longer DOA r/t slower uptake |
| Benefit of spinal in OB | Good for an urgent instrument delivery, manual removal of retained placenta, and repair of laceration |
| Usual spinal dose of LA for OB | Lidocaine 50-75 mg of 1.5-2% solution |
| When is a paramedian approach best | Allows avoidance of sometimes calcified and narrow interspinous spaces |
| Initial needle placement when attempting a paramedian spinal | 1cm lateral and 1cm inferior to midline with a 15-20 degree angle toward midline and slightly cephalad. |
| What structures are avoided with a paramedian approach? | The supraspinous and paraspinous ligaments will not be transected. The ligamentum flavum will be the first ligament entered. |
| GI system effects of spinal anesthesia | Sympathetic block leads to unopposed parasympathetic tone leading to a small contracted gut with relaxation of the abd muscles. |
| Taylors approach | Paramedian approach to L5-S1. Palpate posterior superior iliac spines. Enter with needle 1cm medial and 1cm caudal with needle directed cephalad and medial....walk of sacrum |
| Clincal features of postdural puncture headache | Occurs a minimum of several hours after dural puncture, is usually bifrontal and occiptal w neck & shoulder involvement. Upright position & coughing make it worse while laying down makes it better. Pt will have photophobia & feel helpless & miserable |
| 3 factors that place a pt at higher risk for a post dural puncture headache | Female, younger, OB pt |
| Treatment for postdural puncture headache | Caffeine and fluids for conservative management. If this does not work, an epidural blood patch may be attempted which involves the injection of 5-15cc of autologous blood followed by supine position for 30-60minutes. |
| Cauda Equina syndrome symptoms | Results in lower extremity weakness, pain, and incontinence |
| Cauda Equina Syndrome Causes | Most likely associated with cont spinal techniques and neurotoxic doses of LA. Thought to result from pooling of LA in the sacrolumbar region intead of spreading to the thoracic region. |
| barbotage | mixing CSF with injectate to be used for spinal |
| Factors that will NOT affect the height of a block during spinal anesthesia | Added vasoconstrictor, coughing/straining/bearing down, barbotage, rate of injection (except hypobaric), needle bevel (except whitacre), genter weight |
| Specific Gravity | Density of a substance divided by the density of water. The answer is dimentionless. |
| Mixing hypobaric Tetracaine | 20mg of crystals mixed with 2 mL of distilled water to yield 1% solution with a baricity of 0.9977 |
| Mixing hypobaric bupivicaine | 0.5% bupivicaine warmed to 37 degrees celsius (0.5-0.75 bupivicaine, unwarmed is isobaric) |
| Most commonly used isobaric LA solutions | Tetracaine or bupivicaine mixed with CSF. |
| How far will isobaric LA solution rise? | isobaric LA solutions will not rise above T10. |
| Hyperbaric LA solutions | Lidocaine, bupivicaine, tetracaine mixed with glucose. |
| Where will a hyperbaric block settle in a supine patient | T5-7 |
| 4 factors that affect uptake | 1. Concentration of LA 2. Surface area of nerve root exposed to LA 3. Lipid content of nerve tissue 4. Blood flow to nerve tissue |
| Patients who might not tolerate spinal anesthesia | Patients with fixed volume cardiac states such as IHSS or sever arotic stenosis. |
| Myocardial Oxygen supply/demand with after spinal anesthesia | Decreased in myocardial O2 supply may be insignificant r/t decreased demand. Decreased demand r/t decreased afterload (dec resistance), decreased preload (dec workload), and decreased HR. |
Created by:
mandyrosern
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