Regional

Lateral Femoral Cutaneous Nerve Block

-A lateral femoral cutaneous nerve block would be more appropriate for a lateral thigh procedure -The lateral femoral cutaneous nerve emerges underneath the inguinal ligament and becomes superficial inside the fascia lata near the anterior superior iliac spine -inset needle 2 cm at the inguinal crease just medial to the anterior superior iliac spine and inject 5-10 ml of LA

Cardiovascular Effects

*predominant action of sympathetic block (thoracolumbar division at the intermediolateral horn ) due to LA is venodilation VENODILATION: -reduces venous return -stroke volume -cardiac output -blood pressure If sympathetic outflow from T1-T4 is blocked: -unopposed vagal stimulation will produce bradycardia --> Bainbridge reflex BRADYCARDIA: not only associated with cardioacceleratory fibers but also with decreased venous return --> decreased atrial filling ---> diminished atrial stretch receptor action potentials ---> reflecting decrease in HR Management of hypotension: -IV fluids is not normovolemic (balanced salt solution) -Ephedrine: most effective vasoconstrictor -phenlephrine is HR is high -most effective left lateral tilt if pregnant

Field Block

-A field block is the injection of a typically large volume of local anesthetic in the subcutaneous tissue in order to block cutaneous nerves. A superficial cervical plexus block is an example of a field block that may be used to provide anesthesia for carotid endarterectomies. The radial nerve block is considered a field block because of its less predictable anatomic location and division into numerous smaller branches.

Transtracheal Block

-A transtracheal block is an effective method of anesthetizing the airway for awake airway procedures. -Aspiration should be performed continually while the needle is directed CAUDALLY -On deep inspiration, the local anesthetic should be injected into the trachea. The patient will cough, which will spread the local anesthetic throughout the trachea.. -When air bubbles are seen in the syringe, the tip of the needle is in the trachea. -A transtracheal block is performed by injecting 4mL of 4% lidocaine through a needle penetrating the cricothyroid membrane into the trachea -A transtracheal injection of 4 mL of 4% lidocaine will anesthetize the recurrent laryngeal nerve, which provides sensation to the larynx below the vocal cords.

Thoracic Paravertebral Block

-Although intravascular injection, nerve damage, and failed block are all potential complications of a thoracic paravertebral block, the most common is pneumothorax. The aspiration of air during this procedure mandates a chest film to evaluate for pneumothorax -Thoracic paravertebral block (TPVB) is indicated for postoperative pain control for procedures such as breast surgery, thoracotomy, cholecystectomy, renal surgery, liver surgery, cardiac surgery, neuralgia, and relief of pain due to pleurisy and rib fracture. -produces both a somatic and sympathetic block on the side of the injection -once the needle contacts the bone, it should be walked off the process superiorly and advanced until a loss of resistance is encountered as the needle crosses the superior costotransverse ligament. Usually this is another 1-1.5 cm beyond the transverse process

Wrist Block

-Epinephrine should not be added to the local anesthetic used for wrist blocks as it could compromise distal circulation. -ulnar nerve can blocked as it passes between the flexor carpi ulnaris tendon and the ulnar artery. -median nerve may be blocked as it passes between the palmaris longus and flexor carpi radialis tendons although it should be noted that the palmaris longus may be absent in some patients -A median nerve block at the wrist is performed by injecting 2-5 mL (4 ML) of local anesthetic in the carpal tunnel using a short, B-bevel needle between the long palmar muscle and the radial flexor muscle proximal to the proximal crease of the wrist. An additional 2-3 mLs are injected as the needle is withdrawn from the carpal tunnel. - radial nerve block is considered a field block because of its less predictable anatomic location and division into numerous smaller branches

Combined Spinal Epidural

-In combined spinal and epidural analgesia, the spinal and epidural needles may be placed at the same site or at different sites. The epidural space should be identified with the use of air because the use of saline may create a potential confusion between saline and CSF. -The main advantage of a two-level combined spinal/epidural anesthetic is that it allows the anesthesia provider the ability to test the function of the epidural catheter prior to placing the spinal anesthetic. -Disadvantages of the two-level method include: difficulty distinguishing between the epidural test dose and CSF when performing the spinal anesthetic, CSF flow may be hindered by the compression of the dural sac by the epidural test dose, the epidural catheter can be cut by the spinal needle, and there is a risk of dural puncture with the epidural catheter -Injection of solution through the epidural catheter is known to increase the spread of the spinal anesthetic. It is believed that the increased volume injected into the epidural space compresses the subarachnoid space, resulting in an increase in pressure that 'pushes' the local anesthetic in the subarachnoid space higher. Another cause is the leakage of local anesthetic from the epidural space into the subarachnoid space via the dural puncture made for the spinal anesthetic. -A two-level combined spinal/epidural is performed by first placing the epidural catheter, then performing a spinal anesthetic one or two interspaces below the epidural To avoid catheter migration during or following the combined spinal epidural anesthetic, the spinal needle gauge best used = 28

Bier Block

-Intravenous regional anesthesia technique -Done by IV administration of LA into a vein distal to a tourniquet Tourniquet: -The tourniquet pressure should be around 250-300 mmHg for arm (usually 100 mmHg about SBP) and 350-400 mmHg for the leg -Patients can tolerate a procedure under Bier block for a longer period of time if a double-tourniquet is used. -The distal cuff is inflated first followed by the proximal cuff. -The distal cuff is then deflated to allow the area under it to become anesthetized. If the proximal cuff of the tourniquet becomes too painful for the patient to tolerate, the distal cuff can be inflated and then the proximal cuff deflated to allow the surgeon more time to complete the procedure. Proper time: -To avoid a rapid bolus of intravenous local anesthetic that could result in local anesthetic toxicity, the tourniquet should remain inflated for a minimum of 15 to 20 minutes as was the case in this procedure -tourniquet time should not exceed two hours. LA: -0.5% Lidocaine most likely used -40-50 ml for the arm -100 ml for the leg -bupivicaine should never be used for this block (CI due to its cardiovascular toxicity) -vasoconstrictors are not used Limitation -long procedures where the anesthetic may no longer be effective -tourniquet discomfort Contraindications: -infection of the extremity -poor circulation -history of seizure disorder -heart block

Obturator Nerve Block

-obturator nerve block would be appropriate for procedures on the medial thigh such excision of a medial thigh mass or a release procedure on the medially located adductor muscles. -The obturator nerve provides sensation to the medial aspect of the thigh and motor innervation to the adductor muscles located in the medial thigh.

Femoral Nerve

-The femoral nerve maintains a lateral position in the femoral canal. In order from lateral to medial the structures are remembered by the acronym NAVEL (nerve, artery, vein, empty space, and lymphatics) -A femoral nerve block will provide anesthesia for the anterior thigh, knee, and a portion of the medial aspect of the foot.

Trigeminal Nerve

-The mucous membranes of the nose are innervated by the opthalmic division of the trigeminal nerve (V1) anteriorly and the maxillary division of the trigeminal nerve (V2) posteriorly. These nerves are also known as the anterior ethmoidal and sphenopalatine nerves respectively.

Popliteal Block

-The popliteal nerve is a branch of the sciatic nerve. In fact, all of the nerves supplying the foot and ankle are branches of the sciatic nerve except for the saphenous nerve which is a branch of the femoral nerve. The saphenous nerve supplies sensation to the anteromedial foot and is located anterior to the medial malleolus. A nerve block in the popliteal fossa will anesthetize both the common peroneal and tibial branches of the sciatic nerve which terminate as the superficial peroneal, deep peroneal, sural, and posterior tibial nerves -35-40 ml of LA is delivered during a popliteal block -The sciatic nerve does divide into the tibial and common peroneal nerve, but does so at the upper boundary of the popliteal fossa, -The popliteal artery may be found immediately lateral to the semitendinosus tendon. -The popliteal fossa is bounded laterally by the biceps femoris tendon and medially by the semimembranosus and semitendinosis tendons.

Penile Block

-The pudendal nerve divides into dorsal and ventral branches and provides sensory innervation to the penis. -Sensation to the base of the penis is provided by the pudendal nerve and subcutaneous branches of the genitofemoral and ilioinguinal nerves. -The block should employ 10-15 mL of local anesthetic without epinephrine in a fan-shaped field block at the superior aspect of the base of the penis. -The injection of large volumes of local anesthetic or injection of a local anesthetic that contains vasoconstrictors such as epinephrine can jeopardize blood flow to the penis. -When blocking the dorsal nerves, a 25-gauge, 0.75-1 inch needle is inserted at the 10:30 and 1:30 positions at the base of the penis. The needle is inserted just inside Buck's fascia and 1 mL of local anesthetic is injected on each side.

Glossophargneal block

-blocks posterior 1/3 of the tongue -The glossopharyngeal block is performed by having the patient open their mouth while using a 25-gauge needle to inject 2 mL of local anesthetic bilaterally at the base of the palatoglossal arch (also called the anterior tonsillar pillar). This blocks the lingual and some of the pharyngeal branches of the glossopharyngeal nerve that provide sensation to the posterior third of the tongue and oropharynx.

Digit Block

-epinephrine containing solutions should not be used -maximum volume of solution = 2 ml of each side of digit should not be exceeded; 4 cc per digit -tourniquet: --caution if patient has Raynaud's disease --15 min limit --do not use rubber band --do not use tourniquet if patient has peripheral vascular disease -small volumes of solution: 2 ml of each side -infection proximal to site of injection is the main contraindication to finger/thumb blocks Transthecal block of the digit: -digit is anesthetized by inserting a 25-27 gauge needle at the base of the metacarpal perpendicular to the palm at the level of the distal palmar crease. -Once contact with bone is made, the needle should be withdrawn slightly and lidocaine 1-2% injected. -No epinephrine should be used as it can result in vasoconstriction that could impair circulation. -A transthecal block only requires ONE injection instead of the multiple injections required to produce a digital block. -no terminal arteries are close enough to the injection site to risk disrupting the arterial supply to the distal finger. -A transthecal block runs the risk of anesthetizing only the VENTRAL aspect of the finger or anesthetizing only the last two phalanges.

Spinal Cord Anatomy

-extends Foramen magnum to L1 - adult -extends to Foramen magnum to L3- newborn (transition takes 20-24 mo) -cord terminates at conus medullar is -filum termiinale extends down and anchors in the lower sacral region Spinal nerves= 31 cauda equina : loer dural ac L1-S5 WIDEST @ L2 (5-6 mm) Narrowest @ C5 (1.0-1.5 mm) Single anterior spinal artery Two posterior arteries Artery of Adamkowitz T9-L 1 *principle site of action for neuraxial blockade is the nerve root Spinal cord enlarge at locations: -The cervical enlargement occurs at C4-T1 and the lumbar enlargement which occurs from L2-S3. The cervical enlargement is due to the nerve roots that produce the brachial plexus and the lumbar enlargement produces the lumbar plexus.

Epidural Neural Blockade

-not as voluminous as the subarachnoid space -space extends from base of skin to sacrococcygeal membrane -there is no epidural space within the cranium -safest point of entry: midline lumbar region -1-2 ml of LA per segment to be blocked in adults -volume decreases with increasing ago -preservative free drug -The hanging drop technique is used to verify that the epidural needle has passed through the ligamentum flavum into the epidural space. A visible drop of fluid is placed on the hub of the epidural needle. Because the epidural space has a slightly NEGATIVE pressure, as the needle enters the epidural space, the drop of fluid will be sucked into the epidural space. -Batson's plexus in the epidural space communicates with the azygous system, which can cause engorgement of the vessels during instances of increased abdominal pressure *Anteriorly, the epidural space is bordered by the posterior longitudinal ligament. Posteriorly, it is bordered by the vertebral lamina and the ligamentum flavum which adjoins it. The vertebral pedicles constitute an incomplete lateral border.

Complications of epidural block

-penetration of BV (especially in pregnant patient_ -epidural hematoma ---big concern ---incidence 1:150,000; ---majority in its with abnormal coagulation (disease process, medication; ---s/s: sharp back and leg pain, numbness, motor weakness ---diagnosis: MRI/CT ---emergency: surgical compression within 8 hours -back pain -dural puncture -neural trauma -air embolism (children with PFO) -subdural catheterization -IV catheterization -infection -headache -hypotension -respiratory depression (late or early resp depression with morphine) -bradycardia -Horners' syndrome (ptosis, miosis, anhydrosis, nasal stuffiness) -Trigemial nerve palsy *In patients presenting for lithotripsy, there is the possibility that turbulence at the air-water interface could cause neural damage if air is used for loss of resistance, better to use saline. Cervical epidural: the risk of injury is more dramatic because the level at which it could occur dural puncture, vascular injury, and neural damage. It is technically a greater risk because the epidural space in the lower cervical region is about 20% of that of the lumbar space. The cervical epidural space is about 1-1.5 cm wide compared to 5-6 cm wide in the lumbar regions. This provides for a much smaller margin of error

Respiratory System

-pulm alterations in healthy patients during subarachnoid or epidural block are usually of little clinical significance -Several ventilatory changes during high spinal are possible: --decreased FRC due to paralysis of abdominal muscles --loss of perception of intercostal and abdominal wall movement as a sensory block reaches the level of T2-T4 --> may cause patient to feel dyspneic -unable to cough if abdominal muscles and intercostal muscles are paralyzed (unable to protect airway) -apnea occurs due to hypo perfusion of the respiratory centers in the medulla secondary to severe HYPOTENSION**

Ultrasound

-see the tip of the needle in relation to anatomical structures -direct visualization of the spread of the LA can improve the quality of the block and help to avoid complications -ability to see anatomic differences form one individual to another -less anesthetic delivered more precisely -potential to increase patient safety -high frequency sound waves (1-50 MHz, typically 2-13 MHz) -wave energy transports sound waves -sound wave are longitudinal mechanical waves of compression and rarefaction of a medium such as air or soft tissue --lower frequencies (2-5 mHz) penetrate deeper tissue --higher frequencies (10-13 mHz) penetrate shallow lying structures less than 4 cm from the skin *Sound passes through/conduct sound well = anechoic (echo lucent) --> appear black on image (ex. blood, CSF) *Sound is almost entirely reflected= hyperechoic --> appears bright white on image (ex. air, bone) *Sound is modestly reflected = hypo echoic --> appears as shades of gray on image Arteries: pulsatile and non compressible Verins: compressible -short axis: cross section of the objects; most common view -long axis: longitudinal view, most helpful following the path of an object -IN PLANE: full visualization of the needle tip and shaft, allowing to watch needle-issue interaction, which is important when trying to avoid certain anatomic structures -OUT OF PLANE: only the tip of the tip of the needle intersects the ultrasound beam path; no visualization of the needle en route to the target tissue Influence needle visibility: -angle of isolation -needle gauge -bevel orientation -receiver gain -needle motion, especially on injection -echogenic modifications **one of the most common reasons for poor visibility of structures is lack of sufficient gel at the skin probe surface

Complications

1.) Infection: high fever, nuchal rigidity, severe headache --> spinal meningitis: streptococci (alpha hemolytic) --> epidural abscess: staphylococcus aurea -hematomas with neurological deficits are best diagnosed with MRI predisposing factor: DM, alcohol, AIDs, advanced age, cancer 2.) Respiratory d/t hypoventilation brainstem or loss of accessory muscles: n/v should be identified as s/s to central hypoxia 3) cardiovascular: hypotension common, most common parturients 4) Backache: most common complication d/t stretching of muscles and ligaments of the back beyond their normal range N/V: Nausea is more common in patients with a block higher than T5, those who have received opioid premedication, experience hypotension, or have a history of motion sickness.

Test Dose

3 ml 1:200,000 epi & 1.5% Lidocaine 3 x 5 mcg/ml = 15 mcg 3 x 15 mg = 45 mg test dose are unreliable in: laboring women used to detect both subarachnoid and intravascular injection

Vertebrae

33 Vertebrae: -7 cervical -12 thoracic -5 lumbar -5 sacral -4 coccygeal High Points: C3 and L3/4 Low Points: T6 and S2

Contraindications

Absolute: -patient refusal/lack of cooperation -infection at the site of injection/Dermatologic condition -coagulation deficiencies -shock or severe hypotension/hypovolemia -Increased ICP -severe aortic stenosis (normal = 2-4; less than 1 mm) -lack of experience of provider -preexisting disease involving spinal cord -operation taking longer than block will last/uncertainty about extent or duration of operation -IHSS/severe atrial stenosis *Note: cardiac disease, whether myocardial, valvular, or ischemic is considered a major contraindication to spinal anesthesia if sensory level of T6 or above are required. Spinal anesthesia is indicated in patients with even severe cardiac disease if only perineal levels of anesthesia are required Relative: -mitral stenosis -major surgical procedure about umbilicus -deformity of spinal column (unsure where medicine will go) -chronic headache or backache -blood in CSF that does not clear -inability to achieve spinal tap after three attempts -failure to obtain free flow of CSF through the lumbar puncture needle -minor abnormalities of blood clotting -pre-exisiting neurological deficit -sepsis -uncooperative patient -stenotic valvuar heart lesion -extreme patient age -morbitz I or II -third degree heart block without pace maker Controversial: -prior back surgery at site of injection -inability to communicate with patient -complicated surgery: prolonged, major blood loss, maneuvers that compromise respiration *Patient refusal is the only true absolute contraindication to neuraxial anesthesia. Severe valvular disorders and hypertrophic cardiomyopathy are not absolute contraindications, but the practitioner should evaluate the severity of the conditions and recognize that the patient would not tolerate bradycardia. Osteoporosis is considered a relative contraindication

Interscalene Block

Advantages: -appropriate for should surgery -risk of pneumothorax is small -landmarks eas to identify in obese patient problems: -ulnar nerve frequently not blocked -paresthesias are elicited Landmarks: -level at cricoid C6 -between middle and anterior scalene muscle; SCALENE GROOVE -level of the trunks -looks like a stop light -patient is supine with neck turned away from side of block -sternocleidomastoid muscle is palpated -roll fingers off posteriorly US: -sternocleidomastoid muscle is superior -middle scalene muscle lateral -anterior scalene muscle medial -stop light in between middle and anterior scalene muscle -carotid artery and interjugular vein are medial close to the anterior scalene muscle Needle insertion and injection: -23 g needle -perpendicular to the floor (45 degrees caudal, posterior and medial) -paresthesias are elicited and then injection performed 20-40 ml -remember ULNAR never may not be blocked Complications: -puncture of VERTEBRAL artery -unintentional epidural or spinal -phrenic nerve paralysis LA: lidocaine, mepivicaine, etidocaine, bupivicaine

Supraclavicular Block

Advantages: -brachial plexus is most compact here -quick onset -arm can be in any position -ulnar nerve included -40 ML (mepivicaine, etidocaine, bpi) -a block performed here will achieve adequate anesthesia of the entire arm and hand Limitations/Problems: -needle paresthesias -difficult to perform or teach -PNEUMOTHORAX -Horner's syndrome and phrenic nerve block often occur with supraclavicular blocks, but the most serious complication with this approach is a 1-6% chance of pneumothorax Landmarks/US: -brachial plexus looks like a bundle of grapes here -superior to the first rib (lung pleural right below) -medial is the subclavian artery -middle scalene remains lateral -anterior scalene remains medial -at this level the brachial plexus is located posterior to the subclavian artery between the clavicle and the first rib, the brachial plexus is tightly compacted. CI: -uncooperative patient -difficult stature -severe respiratory disease -bilateral upper extremity block: would result in bilateral phrenic nerve block Postion: -positioned supine with the head turned to the opposite side Technique: -A skin wheal is raised posterior to the subclavian artery at the most inferior point of the interscalene groove. A 22-gauge, 1.5 inch needle enters the wheal posterior to the pulse and is directed caudally until a paresthesia or muscle contraction (if using a nerve stimulator) is elicited. If blood is aspirated, redirect the needle posteriorly and laterally. If the first rib is encountered, walk the needle in an anterior to posterior manner.

Infraclavicular Block

Advantages: -nerves frequently missed with the axillary approach are blocked -blocking below the level of the first rib will not eliminate the potential for pneumothorax -the musculocutaneous nerve is blocked -unlike the axillary approach it does not require positioning of the arm -40 ML Limitations: -no pulse to assist in location of bundle -needle must be advanced blindly -if injection is too far proximal to the clavicle, the musculocutaneous and axillary nerves will be missed -Pneumothorax, difficult to perform Position/US: -cord section of the brachial plexus: may be able to distinguish lateral cord, posterior cord and medial cord -congregates around the axillary artery -pectoris major and minor superior

CSF

Amount at any given time: 100-150 ml Amount in subarachnoid space: 25-35 ml Amount produced a day : 500ml Pressure: 10-20 cm H2O -The specific gravity of the CSF can increase with hyperglycemia, uremia, and increased age and may decrease with liver disease.

Order of Nerve block

BeCause A[dealer gave better acid] 1) B fibers: preganglionic autonomic fibers 2) C fibers: postganglionic sympathetic fibers; pain, temp, touch 3) A delta: pain, temp, touch 4) A gamma: muscle tone 5) A beta: proprioception/pressure 6) A alpha: proprioception/motor smaller B, C, A delta fibers are found on the outside to the nerve bundle, larger A gamma, beta, alpha fibers are found on the inside of the nerve bundle Assessment of sensory block: -alcohol swab: loss of temp = most sensitive indicator of INITIAL ONSET of sensory block -pinprick is most ACCURATE assessment of overall sensory block

Agents

Chloroprocaine: 9.1, onset = fast, DOA: 60 min procaine: 8.9, onset = fast, DOA: 90-130 mins lidocaine: 7.7, onset=intermediate, DOA: 90-150 mins mepivicaine: 7.7, onset= intermediate; DOA 120-160mins Bupivicaine: 8.1; onset =slow, DOA 250 mins Ropiciaine: 8.1; onset= slow, DOA 450 min *The addition of epinephrine prolongs the duration of tetracaine the most, lidocaine moderately, and has almost no effect on the duration of action of bupivacaine.

Nerve Avenues to the Lower Leg

Two major nerves supplying the leg: 1) Femoral (L1-L4) --> Saphenous (just below the knee, the femoral nerve continues not the leg as the saphenous nerve) 2) Sciatic (L4-S3) --> Tibial and Peroneal; proximal to the knee, the sciatic nerve bifurcates into the common peroneal never and the tibial nerve. ---Common peroneal --> superficial peroneal and deep peroneal nerve ---Tibial--> posterior tibial and sural nerve

Cervical Plexus

C1-C5 phrenic nerve C3,C4, C5 -->C4 making 70% of the contribution *the sensory and motor fibers can be blocked separately vertebrae -C1: atlas -C2: axis -C7: prominent -only Technique: -turn patients head to opposite side -draw a line from the tip of the mastoid process of the temporal bone to the anterior tubercle of the TRANSVERSE PROCESS of the 6th cerical vertebra (C6) -22g needle -penetrate the skin over each point, directing the needle slightly CAUDAL until contact is made with each transverse process - no blood of CSF should be aspirated -4 ml PER LEVEL you wish to block -can block superficial (field block) -or deep Complications: -block of the phrenic nerve (C3,4,5) --> causes hiccups -Horners syndrome (stellate ganglion block: LOCATED @ C7)--> ipsilateral ptosis, mitosis, facial and arm FLUSHING, anhydrous, nasal congestion *main risk vertebral artery injection -subarachnod anesthesia is also a potential risk -block RLN -A deep cervical plexus block involves three separate paravertebral injections at the C2, C3, and C4 levels. With the patient supine and the head turned to the opposite side, a line is drawn from the mastoid process to the C6 tubercle. Another line is made 1 cm posterior to this line. The C2 transverse process can usually be palpated on this line about 1-2 cm inferior to the mastoid process. The C3 and C4 transverse processes can usually be palpated at 1.5 cm intervals below the C2 transverse process. Skin wheals are made over each transverse process and a 22-gauge, 5-cm needle is inserted perpendicular to the skin at a slightly caudad angle. If a paresthesia is obtained after contacting the transverse process, and aspiration is negative for blood and CSF, 3-4 mL of local anesthetic is injected. *Some practitioners will perform this block with a single 10-12 mL injection at the C4 process and use distal pressure and a head-down position to encourage spread of the anesthetic to the C3 and C2 nerve roots.

Dermatones

C4: clavicle C7: posterior: most prominent cervical spinous process T4-T5: nipples T6-T8: xiphoid T7: posterior: inferior border of scapula (lower tip) T8: lower border of rib cage T10: umbilicus L1: inguinal ligament L2-L3: knows and below L4: iliac crest (Tuffiers line/Interasited line) S2-S5: perineal

Brachial Plexus

C5-C8 T1

Supraspinous

C7 to sacrum thickest and broadest in the lumbar region

Retrobulbar block

Complications: -Retrobulbar block may result in bradycardia as there is a risk of eliciting the OCULOCARDIAC reflex (5&10) during injection. -Because of potential trauma resulting from puncture or perforation of the globe or HEMORRHAGE from puncture of a vessel located behind the globe, BLINDNESS is a potential risk of retrobulbar block. -Myopia or a previous history of scleral buckle surgery increases the risk of globe penetration by the needle as they both are associated with an increased anteroposterior length of the globe. A recessed eyeball also increases the risk of injury. -SEIZURES probably represent the inadvertant intravascular injection of the local anesthetic during the procedure. Accidental injection into the opthalmic artery will drive the local anesthetic in RETROGRADE fashion through the internal carotid artery and then to the circle of Willis. (Intra arterial injection the most common complication (incidence 1-3% -Injection into the optic nerve sheath Performed: -The injection is typically only performed below the globe as most of the vessels are positioned superiorly to the globe. -Although the larger volume of anesthetic injected when performing peribulbar blocks results in akinesia of the EYELIDS, retrobulbar blocks typically leave the orbicularis oculi muscles intact, requiring a separate block of the FACIAL NERVE branches supplying these muscles to achieve akinesia. Anesthesia: -General anesthesia is suitable for patients who are anticoagulated, cannot control their eye movement adequately, or suffer from too much anxiety or discomfort to tolerate any other forms of anesthesia. -With topical anesthesia, there is little risk of ocular injury and the technique is perfect for an anticoagulated patient or a monocular patient who would be blind from the amaurosis induced by the retrobulbar block. -Retrobulbar and peribulbar block would not be indicated for a patient who is anticoagulated.

Spinal Meninges

Dura Mater: -outmost, tough, longitudinal fibrous tube -foramen magnum to S2-3 Arachnoid: -middle layer -delicate, nonvascular -ends @ S2 Pia: -delicate -HIGHLY vascular -subarachnoid space lies between arachnoid and pia mater; this is where CSF is found

Spinal Trouble shoot

no CSF flow: rotate the needle to see if CSF flow is present in another quadrant, continue rotating the needle in all four quadrants

Ankle Block

Five Nerves 12 going clockwise: 1) Deep peroneal nerve 2)superficial peroneal nerve 3) surval nerve (lateral) 4)posterior tibial nerve 5)saphenous (medial) Tibial nerve: -largest division of the society trunk with fibers from L4-S3 -sensation to skin of heel and medial side of the sole of the foot -anesthetize with 5 ml of LA Superficial Peroneal nerve: -branch of the common peroneal nerve -sensation to dorsal of foot and adjacent sides of the first through fifth toes Saphenous -largest sensory brach of the femoral nerve -originates from fibers L3-L4 -supplies skin on the medial side of the legs, angel and onto the foot -medial anterior calf and the dorsum of the foot. Sural nerve: -a branch from the posterior tibial nerve -immediately lateral to the achilles tendon -senstation to posterior lateral aspect of lower calf and later side of the foot and fifth toe Deep Peroneal Nerve -runs in anterior compartment of leg as a continuation of the common peroneal nerve -enters the ankle between the extensor hallicus longus and the extensor digitorum longus tendons -innervates toe extensors and provides sensation to the medial half of the dorsal foot, especially the 1st and 2nd digits Femoral braches into saphenous: The injection of local anesthetic superficially near the inferior border of the medial malleolus will anesthetize the saphenous nerve.

Indications

Full stomach Anatomic distortions of the upper airway TURP (need T8-T10) Obstetrics Simpler and Faster Decreased Postop pain Continuous infusion

Anticoagulation/Antiplatelet

IV Heparin: -should not receive neuraxial anesthesia until normal PTT documented -one hour after placement of neuraxial anesthetic -indwelling catheters removed 2-4 hours after last dose -heparinization one hour after catheter 1;2-4;1 Warfarin: -discontinue at least 4 days before surgery -dose within 24 hrs surgery --> INR checked immediately -INR < 1.5 okay for block -catheter not removed until INR < 1.5 Fibrinolytic/Thrombotic: 10 days Ticlodipine: 14 days Clopidogrel: 7 days Abciximab: normal put aggregation occurs 24-48 hrs after Eptifibatide and Argatroban: normal put aggregation occurs 4-8 hrs after Use of GPIIb/IIIa antagonists contraindicated for 4 weeks after surgery LMWH: -once daily dose: --first dose 6-8 hours postop --next dose not administered for 24 hours --indwelling catheters not removed 10-12 hrs after last dose --okay to dose 2 hours after catheter removed *If LMWH is planned postoperatively, the epidural catheter should be removed at least 2 hours before the first dose. -twice daily dose: --first dose no earlier than 24 hours posop regardless of technique --remove catheter before initiation of LMWH --continous epidural catheters may be left indwelling overnight and removed the following day --okay to dose 2 hours after catheter removed *Pts who are anticoagulanted who receive a central nerve block should be monitored closely for s/s of neurologic impairment such as spinal or epidural hematoma and neurological impairment

Subarachnoid Space

In adults, the subarachnoid space extends from the foramen magnum to S2 and extends to S3 in children. The spinal cord itself extends to L1 in adults and L3 in children.

PDPH

Incidence: 0.2-0.4% -highest in OB -within several hours but usually 1st, 2nd day post puncture -earlier onset = more severe it will be -bifrontal and occipital; involving head, neck, shoulders -agrivated upright position, received by lying down -s/s: loss of appetite, photophobia, n/V, changes in auditory acuity, tinnitus, depression, feel miserable, tearful, bed ridden, dependent, diplopia, cranial nerve palsies -decreased in the amount of available CSF in the subarachnoid space --> causes stretching of meninges, vessels, and nerves, leading to headache ; an additional complication of decreased CSF volumes is racial nerve palsy which leads to decreased blood supply to the nerves Risk factors: -large cutting needle -perpendicular to parallel fibers -epidural needle -women> men -young> elderly -Ob BLood Patch: 10-30 cc aseptically drawn blood if patient volume depleted it is desirable to infuse 1000 cc IV The blood patch is injected into the epidural space (usually below the original site) until the patient can feel pressure in his back -after EBP; best rest for 1-2 hours before ambulating -first blood patch 89-95% effective -may repeat within 24 hours -pain relief should be instantaneous backache, neck ache, temperature elevation and radicular pain may be s/s

Intercostal nerve Block

Intercostal nerves of primary rami T1-T11 VAN -The intercostal neurovascular bundle travels on the inferior surface of the rib. From superior to inferior in the bundle are the vein, artery, and nerve. -The correct rib is identified by palpation, a skin wheal is made directly over it at the level of the MIDAXILLARY LINE, and then a 22 or 25 gauge needle is walked off the INFERIOR border of the rib and advanced about 0.5 cm. After careful aspiration for blood or air, 3 to 5 mL of local anesthetic is injected. -left hand firmly placed against patient's back controlling needle -needle at 15-20 degree angle cephalad Complications: -Pneumothorax -toxicity of LA -total spinal -nerve injury

Caudal Epidural Block

MOST COMMON FORM OF RA IN PEDIATRIC POPULATION: -postion patient (neonates are first put to sleep) -palpation of landmarks -needle insertion through sacrococcygal membrane correct needle placement: -sacral bone is present on each side of it, in front of, and behind the needle at its point of insertion -needle placed in the SACROCOCCYGEAL MEMBRANE -CSF, air, or blood should not be aspirated -No subcutaneous bulge or crepitus should occur after injection of 2-3 ml of air or anesthesia solution -injection should feel like injecting into the epidural space -"Whoosh test with air while listening with your stethoscope over midline lumbar spine -if properly placed the needle should move in the canal, pivoting at the point of penetration -there should no local pain on injection; if pt has pain, stop injection -paresthesia or feeling of fullness from the sacrum to the soles of the feet occurs during injection and ceases upon complettion -feeling of grating as the needle moves along the anterior wall of the sacral canal. -When performing a caudal anesthetic, the needle or intravenous catheter is advanced toward the sacral canal at a 45 degree angle towards the head until a pop is felt as it pierces the sacrococcygeal ligament. The angle of the needle is then flattened and advanced. VOLUME: -premature infant: inguinal hernia repair: chloroprocaine, 1 ml/kg as bolus, then 0.3 ml/kg until desired level is met -children: 0.5-1 ml/kg of 0.125 to 0.25% bupivicaine (4-6 hrs) -volume range of 25-35 ml is required to get a sensory block at T10 to T12 ---> S5-L2: 15-25 ml ----> S5-T10: 35 ml -high plasma levels of local anesthetic after caudal adminstration, compared to lumbar epidural -distribution time of a caudal is longer than lumbar epidurals Potential problems: -Complication: slight risk of neurologic damage -injection sit pain is most common COMLPAINT -most frequent PROBLEM = ineffective blockade -urinary retention -infection -The epidural sac extends to about L2 in adults and S4 in children making inadvertant intrathecal injection more likely in children. postop problmes: -pain at injection site is the most common postoperative complaint -urinary retention -infection: risk is present -slight risk of neurological damage Surgeries: Caudal anesthesia is a useful adjunct for surgeries below the level of the umbilicus. Omphaloceles are herniations through the umbilicus through which abdominal contents protrude. Clubfoot repair, inguinal herniorrhaphy, and circumcision are all surgeries that would benefit from the pain relief provided by a caudal block. *The two sacral cornua, the coccyx, and the posterior superior iliac spines can all be used as anatomic landmarks to identify the correct placement of the needle for a caudal bloc postion: either lateral or prone A caudal anesthesic is used predominantly in pediatric anesthesia because in patients under the age of 12 the spread of LA in the caudal epidural space is more reliable and the sacral hiatus is larger Adult caudal: -A 3 mL test dose is administered first. For sacral procedures: -S5-L2: 12-15 mL is sufficient. -S5-T10: 20-30 mL is usually required for anesthesia up to a T10 dermatome. Peds: -0.5-1.0 ml/kg of 0.125-0.25% bupivicaine Premature: chloroprocaine: 1 ml/kg bolus 0.3 ml/kg until desired level met

Musculocutaneous nerve

Movement: -flexion elbow Because the musculocutaneous nerve branches off of the brachial plexus very early, it is typically not blocked with an axillary approach leaving its distribution to the lateral forearm intact. For procedures that may involve that distribution, an axillary block should be augmented with a 5-8 mL local anesthetic injection into the CORACOBRACHIALIS muscle where the musculocutaneous nerve emerges. The addition of 20 mL to the axillary block would not reach the musculocutaneous nerve. Injecting 2-3 mL at the level of the ulnar styloid across the volar aspect of the forearm would block the radial nerve which would provide anesthesia to the lateral 3 1/2 fingers. Injecting 3-5 mL of local anesthetic at the posterior surface of the elbow just proximal to the arcuate ligament would block the ulnar nerve.

Ulnar Nerve

Movements: -Adduction Thumb -fterm-46lexion wrist -flesion and opposition of medial two fingers toward thumb Ulnar Block at the ELBOW: - flex patient's elbow 90 degrees -identify medial epicondyle of humerus -insertion point of needle is between the medial epicondyle of the humerus and the olecranon process of the ulna -4 ml AT THE WRIST: -wrist slightly flexed -identify flexor muscle or wrist -insert B bevel needle slightly adjacent to ulnar artery (ulnar artery medial and flexor carpi ulnaris tendon lateral) -2-4 cc -block of dorsal bench of ulnar nerve requires a lidocaine wheal around the ulnar portion of the wrist

Radial nerve

Movements: -EXTENSION (only one to extend) elbow, wrist, fingers -abduction thumb -supination forearm (rad soup) Block At the ELBOW: -elbow extended (remember radial nerve EXTENDS everything) -locate brachioradialis muscle and the biceps brachii muscles insertion (tendon) -radial nerve is in the groove between the muscle mentioned aboe -4 cc AT THE WRIST: -wrist placed in a neutral position ('handshake') -inject subcutaneous ring (field block) of LA, beginning at the radial flexor muscle and extending to the dorsal surface of ulnar styloid - avoid formation of a continuous ring of LA around the wrist when done in conjunction with an ulnar block, as circulation of the hand could be compromised -6 cc Damage to the radial nerve (arising from the C6-T1 nerve roots) can result in weak thumb abduction, inability to extend the metacarpophalangeal joints, and loss of sensation in the web space between the thumb and index finger. Common causes include pressure from the vertical bar of an anesthesia screen and excessive cycling of an automatic blood pressure cuff.

Median Nerve

Movements: -pronation forarme -flexion wrist -oppostition middle, forefinger, thumb and flexion of the lateral 3 fingers -innervation to the muscles of the thenar eminence, the forearm flexors, and the lumbrical muscles of the first and second finger Locations: In brachial plexus: from the lateral and medial cord In wrist: between palmaris longus and flexor carpi radialis tendons Elbow: -draw a line from medial to lateral condyles of the humerus on anterior surface -insert B-becel needle slightly MEDIAL TO BRACHIAL ARTERY, toward the center, lateral side is the biceps -4 cc AT THE WRIST: -flex wrist against resistance -palpate palmaris longus tendon and the flexor carpi radials tendon -insert B bevel between the two tendons/muscles -2-4 ml

Lumbar Plexus and "Three is One Block"

NAVEL -provides anesthesia for the anterior thigh, knows and a small portion of the medial calf and foot -may be used in conjunction with other lower extremity blocks -The insertion site should be 1.5-2.0 cm lateral to the femoral pulse, 2.0 cm inferior to a line drawn between the pubic symphysis and the anterior superior iliac spine -you could also identify the inguinal ligament and then palpate for the femoral pulse -enter 2 cm lateral to the femoral pulse and 2 cm distal to the inguinal ligament -peripheral nerve stimulator with a 2 inch 22g stimulating needle and look for a quadriceps twitch or patellar snap -once the nerve is identified, turn the PNS to less than 0.5 mA and inject 1 ml of LA anesthetic and observe the fade -aspirate and deposit 30 ml of LA -useful in numerous procedures involving the thigh and knee -3-in-1 = lateral femoral cutaneous nerve, femoral nerve, obturator nerve *The posterior branches of the femoral nerve provide motor input to the quadriceps. The anterior division innvervates the sartorius muscle

Sciatic Block

Originates: form the lumbosacral trunk and is composed of L4-L5, S1-3 -supplies sensory fibers to the posterior hip capsule as well as to the knee -motor activity to the hamstring and to all lower extremity muscles distal to the knee -all sensory innervation to the lower extremity distal to the knee, except along the anteromedial aspect, which is covered by the saphenous nerve -breaks into the peroneal and tibial nerve proximal to the popliteal crease -A sciatic nerve block will provide anesthesia for the knee and all structures distal, but will not provide anesthesia for the placement of a tourniquet on the thigh. Anterior Approach: -supine postion -leg slight internal rotation, toes inward -inguial ligament identified, marked and divided into thirds -At the junction of the medial and middle turn, a perpendicular line is drawn that intersects the greater trochanter line at a right angle -4 inch, 21g insulated stimulating needle is inserted at this intersection -motor response in the distal ankle, foot, toes -Reduce PNA to 0.5 mA and witness fade after injection of 1 mL -aspirate and then deposited 20 ml of LA Complications: partial block due to branching of the sciatic nerve, and intraneural injection *nearly all skin of the leg is innervated by the sciatic nerve

Axillary Block

RUMM PISS -best suited for surgical procedure on the elbow, hand, forearm -low incidence of complications -high success rate -ease of performance -most frequently used Within the brachial bundle: -Radial nerve: posterior, lateral and closer to humorous -Ulner nerve: most inferior, more medial -Median: superior but in the brachial bundle -Musculocutaneous: superior but out of the brachial bundle in the CORACOBRACHIALIS muscle Advantages: -most population technique for blocking the nerves of the arm -poluarity based on minimal number of complications -provides anesthesia for surgery on the forearm -fewer complications than for supraclavicular block -safest, most reliable for the patient Limitations: -arm must be abducted to perform block -not for shoulder or upper arm surgery -musculocutaneous nerve lies outside the sheath and separate block for this nerve is required -circumflex block may also need to be blocked for total anesthesia US: -all nerves but the musculocutaneous nerve positioned around the axillary artery -biceps are lateral and superior, (above the coracobrachialis muscle) -humerous and triceps inferior, radial nerve closest Technique: -patient is supine with head turned away from arm to be blocked -arm is abducted to 90 degrees, and forearm is flexed to 90 degrees -palpate brachial artery (axillary artery) pulse proximally as far as possible toward armpit -40 ML Complications: -Intravasular injection -increased risk for hematoma -When performing a brachial plexus block using the axillary approach, it is often necessary to perform separate blocks of the medial brachial cutaneous and intercostobrachial nerves because the former exits the sheath just below the clavicle and the latter doesn't travel in the sheath at all. These two nerves provide sensation to the skin of the medial and posterior proximal arm

Needle Structures

SPCA DELI vers -skin -subcutaneous tissue -supraspinous ligament -interspinous ligament -ligamentum flavum -epidural space -dura mater -arachnoid mater -subarchoid space with CSF -pia mater -spine Performance: -When performing spinal anesthesia, two sensations are often felt. The first is similar to passing the needle though a pencil eraser and the second is a distinct pop. -The first pop is the needle penetrating the ligamentum flavum and the second is the needle penetrating the dura mater. Paravertebral approach: -will not pass the: --supraspinous ligament --interspinous ligament first thing passed after skin and subQ tissue = ligament flavum -When performing an epidural via the paramedian approach, the needle entrance site begins 1 cm lateral to the inferior border of the spinous process above the interspace desired. It is then advanced through the subcutaneous tissue and paraspinous muscles until it strikes the lamina of the inferior vertebra. The needle is then walked medially and superiorly off of the lamina until the ligamentum flavum is reached. Once there, any of the approaches for traversing the ligamentum flavum without interrupting the dura can be applied. If you hit a bone for the paravertebral approach: most likely lamina

Epidural needles

Touhy: 30 degree curve bevel Houston: 15 degree curve bevel *not sharp, bounces off dura, stands catheter in the direction of the bevel Crawford: thoracic, straight, sharp, higher rate of dural puncture Weiss: has wings where the finger are Multiport/mulitoriface catheter: lower incidence of inadequate analgesia; higher incidence of IV cannulation Length of needle to hub: 12-12.5 Skin to epidural space: skinny person: 3 cm normal: 4-5 cm obese: 8 cm Threat catheter into epidural space: 4 cm Properly placed epidural at skin: (4+5=9) at catheter hub: (4+5+12=21cm)

Spinal Block Pharmacology

Vasoconstrictors: -prolong duration of spinal block -epinephrine @ 0.1-0.2 ml (1mg/ml) to prolong duration of spinal (not to be used in nose, toes, hose) -phenylephrine @ (good drug to use if you don't want to increase HR and myocardial demand) Onset: -quickens onset by changing pH -Bicarb more alkalotic Spread : starts with an H look it up Duration: -Addition clonidine (1 mcg/kg): increase quality and duration of pain relief but can produce bradycardia, hypotension, sedation Spinal Opioids: -improve duration efficacy of block -Fentanyl 10-25 mcg -sufentanil 10 mcg -preservative-free morphine 250 mcg -clonidine: 15-45 mcg(150 mcg epidural) Baracity: Hyperbaric: -add Dextrose 5-8% --injected at the L3 interspace the spread of the drug in both a cephalad and caudal direction Hypobaric: -dissolve the drug in sterile water Factors with proven effects on distribution of drug: -site of injection -antaomical shape of spinal column (highest L3-> spreads caudal and cephalad) -angulation of needle -patient height -volume of CSF (pregnancy) -Characteristics of local anesthetic --density --specific gravity --baracity -Dose -Volume (epidural) Spinal: -Position of patient (spinal) -site of injection (spinal) -postion after injection -local anesthetic selected -total DOSE administered -addition of opioids **Uptake of LA is the greatest where the concentration of the local anesthetic if the greatest --> uptake occurs by diffusion down a concentration gradient Elimination: -rate of elimination determines the duration of spinal anesthesia -by vascular absorption via subarachnoid and epidural blood vessels (more in epidural) *advantage of spinal over epidural is the ability to control the spread of the anesthetic by controlling the specific gravity go the solution and the position of the pt

Spinal Needles

cutting needles: Quinke: all cutting edge; sharp point Pitkin: sharp point, short bevel cutting edge, rounded heel Pencil Point: Greene: rounded non-cutting bevel Sprotte: large opening on side Whitacrea: small opening on side Postion: -sitting position has dura running parallel to the spinal column. The dura runs cephalad to caudal and fibers are longitudinal: --> a pencil point needle will "separate the dura" --> a cutting needle will need to face either right or left to "separate" rather than tear the dura (which minimizes trauma) Lateral position: --> pencil point: no change --> cut bevel will need to face up or down to minimize trauma

Distribution of Epidural

distribution of LA after injection into the epidural space. There are tow mechanisms of epidural produced conduction block: 1) LA acts directly at the nerve roots and dorsal ganglia beyond the dura after diffusing through the intervertebral foramen 2) LA acts on dorsal and ventral rootlets and spinal cord after diffusing across the drua and arachnoid, or acorss the dural cuff (root sleeve) into the CSF and into the spinal cord

Ligamentum Flavum

hello ligament -short segment between the spinous processes DOES not go the entire length of the cord.. SEGMENTS only

Sympathetic Blockade

other s/s from sympathetic blockade from spinal: -increased tone of urethral sphincter -->result in urinary retention -increased peristalsis -decreases stress response, results in lowered production of cortisol -vasodilation -generalized constriction of the bowel -increased gastrointestinal blood flow, -increased gastric intraluminal pressure

Differential Nerve Blockage

smaller nerves are more susceptible to the actions of LAs than large fibers. Smaller fibers are preferentially blocked , myelinated fibers are more easily blocked than nonmyelinated. Differential blockage is observed clinical but poorly understood -large myelinated fibers are more resistant to LA block that smaller myelinated or unmyelinated fibers -the anatomy of the nerve root may explain the differential blockade -the diffusion path to the larger diameter fibers situated deep in the nerve bundle is longer Spinal: sympathetic 2-6 dermitones above sensory 2 dermatomes above motor Epidural: sympathetic and sensory at same level, motor 6 below With neuraxial anesthesia, a differential block is produced which typically results in a sympathetic block that can be as high as 6 dermatome levels above the sensory blockade. Factors affecting sensory block: -most intense bloc and fastest onset at site of injection -a lumbar epidural injection is associated with greater cranial than caudal spread of LA, there may be a delay in onset in L5 and S1 segments due to the large size of the nerve roots -a mid thoracic epidural is associate with uniform spread of LA, however the upper thoracic and lower cervical segments are resistant to block because of the large size of nerve roots and the large number of nerve fibers within them -T12 level for tourniquet pain

Epidural Space

space that surrounds the spinal meninges -extends from the foramen magnum to SACRAL hiatus -potential space -bound by dura and ligament flavor Which ligament binds the epidural space posteriorly: Ligamentum Flavor Anteriorly: posterior longitudinal ligament

Interspinous

thin membrous ligament full length of the column thickest and broadest in lumbar region