Local Anesthetics

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Local Anesthetics Regional Blocks:

Local Anesthetics Regional Blocks Marty McCullough, CRNA, ARNP, MSN

History:

History Early examples to relieve pain during surgery included loss of consciousness produced by blows to the patient’s head or by compression of the carotid arteries. Pain relief in the arm or leg was produced by squeezing the nerves in the upper part of the limb and also by applying cold water, ice, or snow. Hypnotism became popular in the late 18 th and early 19 th centuries. Anesthesia produced by nerve block or regional anesthesia, became possible after cocaine was isolated from the coca plant in 1860.

History:

History 1844 Francis Rynd invented the hollow needle which was used for delivering hypodermic medications. 1851 Charles Pravaz (French Surgeon) invented the hypodermic syringe. 1854 Alexander Wood (Scottish Physician) improved the syringe. 1884 Dr Karl Koller first produced anesthesia of the skin and mucous membranes by instilling cocaine drops into the eye. 1885 William Halsted introduced the concept of nerve blocks for surgery by injecting the nerve with cocaine. First nerve blocks were of the mandibular nerve.

Pharmacology:

Pharmacology Local anesthetic is a drug that temporarily blocks the transmission of a stimulus along the path of a nerve fiber causing a reversible analgesic effect. It produces an absence of pain sensation and when used on specific nerve pathways (nerve block), paralysis can be achieved. Local anesthetics are weak bases whose chemical structure is connected to an amine through an ester or amide linkage.

Pharmacology:

Pharmacology ESTERS - ester are metabolized by plasma cholinesterase with an elimination half-life in circulation of about one minute. AMIDES - amides are metabolized in the liver with an elimination half-life of 2-3 hours. Patients with severe hepatic disease may be more susceptible to adverse reactions from amide local anesthetics

Pharmacology:

Pharmacology Esters Duration Potency Onset Procaine/Novacaine Short (45-60 min) Low Fast 2-Chloroprocaine Short (30-60 min) Moderate Fast Cocaine (Topical) (NO LONGER AVAILABLE)

Pharmacology:

Pharmacology Amides Duration Potency Onset Lidocaine Moderate (60-120 min) Moderate Intermediate Mepivicaine Moderate (90-180 min) Moderate Intermediate Prilocaine Moderate (60-120 min) Moderate Fast Bupivicaine Long (240-480 min) High Slow Ropivacaine Long (240-480 min) High Slow

Pharmacology:

Pharmacology Adjuvents - Medications added to local anesthetics to prolong the duration of a peripheral nerve block, or speed the onset. Epinephrine Sodium Bicarbonate Opioids

Pharmacology:

Pharmacology Epinephrine Prolongs duration of anesthesia. Varies with type of regional block and concentration of local used. Decreases systemic toxicity by decreasing the rate of absorption. Increased intensity of block. Decreases surgical bleeding.

Pharmacology:

Pharmacology Epinephrine SHOULD NOT be added to local if: Peripheral nerve block in areas with poor collateral circulation (e.g. fingers, toes, penis, ears, etc.) IV regional technique (Bier Block) History of severe uncontrolled HTN, CAD, arrhythmia, hyperthyroid, utero-palcental insufficiency

Pharmacology:

Pharmacology Sodium Bicarbonate Increases the rate of diffusion and speeds the onset of neural blockade. 1 mEq added to each 10mL of Lidocaine or Mepivacaine. 0.1 mEq added to each 10mL of Bupivicaine. “Use just a splash”

Pharmacology:

Pharmacology Opioids Addition of 50-100 μ g of Fentanyl to the local anesthetic shortens the onset, increases the level and prolongs the duration of a regional block. Primarily used in Epidurals or Spinals. Action is synergistic with the action of the local anesthetic.

Pharmacology:

Pharmacology Sedation Most patients are apprehensive about any surgical procedure or office procedure. Any available sedative will calm the patient and facilitate the placement of the nerve block. I use Versed and Propofol, but if time permits, administering any available sedative will be beneficial.

Equipment:

Equipment Appropriate Needle 3-way Stop Cock Extension Tubing 30cc syringe 10cc syringe Betadine Swabs EKG Pad Peripheral Nerve Stimulator Sterile Gloves Skin Marker Appropriate Local Anesthetic Emergency Airway Equipment

Equipment:

Equipment Nerve Stimulators/Nerve Stimulation Eliciting paresthesia or nerve stimulation is a commonly used method for localizing nerves prior to the injection of local anesthetic. Nerve stimulation techniques rely on the use of electric current to elicit motor stimulation of nerves and confirm the proximity of the needle to the nerve. Technique: Start at 2.0mA and find motor stimulation and decrease slowly until you find the mA which motor stimulation ceases. You want it to be less than 0.5mA if possible.

Equipment:

Equipment Emergency Airway Equipment Laryngoscope (MAC 3 or Miller 2 Blade) Endotracheal Tube Stylet 5-10cc Syringe Oralpharyngeal airway Ambu Bag Oxygen tank Laryngeal Mask Airway (LMA)

Contraindications:

Contraindications Patient refusal Systemic Anticoagulation Platelet count less than 100,000 PT, PTT, Bleeding Time greater then twice the normal value Severe Bleeding Hypovolemic Shock Active infection near site of regional technique Patient age, ability to cooperate, history of headaches, chronic neurologic disorders, local anesthetic allergy, or heart block may influence the decision to administer regional anesthesia.

Complications:

Complications Local Anesthetic Toxicity Disorientation Metallic Taste Tingling in the mouth and tongue Tinnitis and Auditory Hallucinations Muscle Spasms Seizures Coma Respiratory Arrest Cardiac Arrest Death

Complications:

Complications Local Anesthetic Toxicity Toxicity of local anesthetics resulting in cessation of breathing and tonic-clonic seizure activity with resultant hypoxia, hypercarbia and profound acidosis is an ever-present risk in the practice of peripheral nerve blocks. Central Nervous System Toxicity caused by Intravascular injection Call 911 Administer oxygen by Non-rebreather at 10L/min Monitor for seizure activity Versed/Valium

Complications:

Complications Nerve Injury Complications following a peripheral nerve block fall into one of 6 major categories 1. Mechanical Trauma to Nerve a. Needle Trauma b. Intraneuronal Injection Neuronal Ischemia Inadvertent needle placement at unwanted location Neurotoxicity of local anesthetic Drug Error (Injection of wrong drug) Infection

Intubation:

Intubation Intubation Indications for Endotracheal Intubation Provide a patent airway for unconscious patient Facilitate positive pressure ventilation of the lungs NEVER ATTEMPT TO INTUBATE AN AWAKE OR SEMI-AWAKE PATIENT Use of Laryngoscope Laryngoscope is held in the left hand The blade is inserted in the right side of the patient’s mouth so the tongue is deflected to the left, away from the lumen of the blade Pressure on the teeth/gums must be avoided as the blade is advanced centrally toward the Epiglottis The wrist is held rigid as the laryngoscope is lifted along the axis of the handle to bring the laryngeal structures into view The handle should not be rotated as it is lifted to prevent using the patient’s upper teeth as a fulcrum with the blade of the laryngoscope as a lever.

Intubation:

Intubation Insertion of Endotracheal Tube ET tube is held in the right hand like a pencil and introduced in the right side of the mouth with the natural curve directed anteriorly. A styleted endotracheal tube is inserted into the right side of the mouth (midline insertion usually obscures visualization of the glottis) . The tube is advanced until the proximal end of the cuff is 1 to 2 cm past the vocal cords. Remove the laryngoscope blade, then while holding the tube firmly pull the stylet out of the ET tube. The cuff of the ET tube is inflated with approx. 5-6cc of air to create a seal against the tracheal mucosa.

Airway:

Airway LMA The LMA is a supraglottic airway device used for routine and difficult airway management. Adult sizes Most women #4 50-70kg Most men #5 70-100kg The LMA is inserted blindly into the posterior pharynx, along the roof of the mouth until resistance is felt. At that point the LMA is positioned in the hypopharynx below the base of the tongue and above the epiglottis. If the appropriately sized LMA is selected, the resistance denotes placement of the LMA’s tip in the hypopharynx. The cuff is then inflated, sealing the airway over the larynx.

Airway:

Airway Oral Pharyngeal Airways (OPA’s) is used to maintain a patent airway by preventing the tongue from covering the epiglottis. Oral airways are ONLY indicated in unconscious people due to the likelihood that the device would stimulate a gag reflex in conscious or semi-conscious patients, resulting in vomiting. Choose the correct size by measuring from the person’s mouth to the angle of the jaw. Place in the patient’s mouth with the tip facing the roof of the mouth, then rotated 180 degrees once contact is made with the back of the throat. Remove the airway when the patient regains a swallow reflex or can maintain their own airway.

Airway:

Airway Nasopharyngeal Airways (Nasal Trumpet) are designed to be inserted into the nasal passageway to secure an open airway. Nasal Airways are to be used in conscious and semi-conscious patients. Nasal Airways are ABSOLUTELY CONTRAINDICATED in patients with severe head or facial injuries, or have evidence of basilar skull fracture because of possibility of direct intrusion into brain tissue. Correct size is chosen by measuring from the patient’s nostril to the earlobe or the angle of the jaw. To insert, lubricate the tube and insert with the beveled edge against the septum and advance until the flared end rests against the nostril.

Documentation:

Documentation Nerve Block Procedure Approach Used Pre-medication Skin Preparation Equipment used (eg: needle, nerve stimulator) Number of attempts Type of response obtained on nerve stimulation Minimal current (mA) accepted Local Anesthetic (type, concentration, additives, volume) Abnormal pressure or pain on injection Signs of block onset Comments

Peripheral Nerve Blocks:

Peripheral Nerve Blocks Basic Technically easy to perform, have low risks of complications, and have wide clinical applicability. Ample expertise is present in most residency programs to allow the adequate training of students. These procedures should be part of the abilities of every anesthetists.

Peripheral Nerve Blocks:

Peripheral Nerve Blocks Basic Peripheral Nerve Blocks Axillary Block Wrist Block Bier Block Digital Block Ankle Block Intercostobrachial Cutaneous

Peripheral Nerve Blocks:

Peripheral Nerve Blocks Intermediate Complexity and potential for complications is greater than for basic block techniques. These procedures are best mastered by spending 1-2 months in a well structured, mentored elective peripheral nerve block rotation during training or with a fellowship in regional anesthesia

Peripheral Nerve Block:

Peripheral Nerve Block Intermediate Peripheral Nerve Blocks Femoral Nerve Block Sciatic Nerve Block Popliteal Block Infraclavicular Brachial Plexus Block Deep Cervical Plexus Block Interscalene Blocks Supraclavicular Interscalene Block

Peripheral Nerve Block:

Peripheral Nerve Block Advanced Highly specialized procedures, most of which require significant expertise in Basic and Intermediate Nerve Block procedures for their implementation. Advanced nerve block techniques are either deeper nerve blocks or blocks that require more specialized equipment and/or the insertion of indwelling catheters for continued infusions of local anesthetics. Most anesthetists require 6-12 months fellowship to acquire sufficient expertise in these techniques

Peripheral Nerve Blocks:

Peripheral Nerve Blocks Advanced Continued Interscalene Brachial Plexus Block Continues Infraclavicular Brachial Plexus Block Thoracolumbar Paravertebral Block Lumbar Plexus Block Continuous Femoral Nerve Block Continuous Sciatic Block Continuous Popliteal Block Sciatic Nerve Block: Anterior Approach

Peripheral Nerve Blocks:

Peripheral Nerve Blocks For this class we will ONLY be focusing on Basic Skill Level Peripheral Nerve Blocks Any Intermediate Skill Level Blocks will be discussed for information purposes only

Upper Extremity Blocks:

Upper Extremity Blocks Axillary Block Wrist Block Bier Block Digital Block Intercostobrachial Nerve Block

Axillary Block:

Axillary Block Indications: Forearm and Hand Surgery Landmarks: Axillary Pulse, Coracobrachialis muscle, Pectoralis major muscle Needle: 3-5cm Insulated Local Anesthetic: 35-40mL Ropivicaine 0.5% Onset: 15-20 min Duration of Anesthetic: 6-8 hours Duration of Analgesia: 8-12 hours Any of the following three endpoints: 1. Nerve stimulation, hand twitch @ 0.2-0.4mA of current 2. Paresthesia of the hand 3. Perivascular blood aspiration (axillary artery)

Axillary Block:

Axillary Block Place patient supine, head facing away from block side, and arm abducted with elbow forming 90 º angle. Palpate the Axillary artery high in the axilla Once the artery in located, position the Index and Middle fingers straddling the artery Insert the insulated needle just in front of the fingers and advance at an angel 45º cephalad.

Axillary Block:

Axillary Block Set the nerve stimulator to 3mA and advance the needle slowly until stimulation of the brachial plexus is obtained (hand twitch). Reduce the nerve stimulator until the cessation of twitching occurs (should be around 0.2-0.4mA). Inject 35-40mL of local anesthetic, aspirating every 5mL. When the axillary artery is punctured before the plexus is stimulated, do not continue searching for stimulation. Resort to the transarterial technique and inject two-thirds of the local posteriorly and one-third anteriorly to the artery.

Wrist Block:

Wrist Block Indications: Surgery of the Hand and Fingers Nerves: Radial, Ulnar, Medial Needle: 1½ inch 25-gauge Local: 6mL per nerve Bupivicaine 0.5% NEVER USE EPI CONTAINING LOCAL ANESTHETIC Onset: 15-30 min Duration of Anesthetic: 5-15 hours Duration of Analgesic: 6-30 hours

Wrist Block:

Wrist Block Three part block: Medial Nerve , located between tendons of the palmaris longus (most prominent of the two) and the flexor carpi radialis. Ulnar Nerve , passes between the ulnar artery and the flexor carpi ulnaris . Radial Nerve , passes the outer side of the radial artery and beneath the supinator longus .

Wrist Block:

Wrist Block Medial Nerve Insert the needle between the tendons of the palmaris longus and flexor carpi radialis. The needle is inserted deep into the fascia until it contacts bone then pull back 2-3mm. A “fan” technique is recommended. Ulnar Nerve Insert the needle under the tendon of the flexor carpi ulnaris muscle closest to its distal attachment, just above the styloid process of the ulna. Radial Nerve Inject subcutaneously just above the radial styloid, aiming medially, then infiltrate laterally. Essentially a “field block”.

Bier Block:

Bier Block Indications: Surgery on Wrist, Hands and Fingers Needles: None required Other: Double Cuff Tourniquet Local Anesthetic: 12-15mL Lidocaine 2%

Bier Block:

Bier Block A small IV catheter is placed in the distal portion of the extremity. The arm or leg is then exsanguinated by wrapping the an elastic bandage. The proximal end of a double tourniquet is inflated to 250-275 mm Hg, or about 100 mm Hg above the patient’s systolic BP. 40-50mL of plain (w/o Epi) local anesthetic is injected into the IV catheter and the catheter is removed.

Bier Block:

Bier Block Beyond 45 min of surgery, many patient’s experience tourniquet pain at the tourniquet site. The distal end of the double tourniquet is then inflated, and the proximal end is deflated. A Bier Block can be used for surgical procedures with a duration of 2 hours or less. Severe tourniquet pain and the maximum allowable tourniquet time, limit the practical duration of the block.

Digital Block:

Digital Block Indications: Surgery of Fingers Nerves: Digital Nerves Local: 2-3mL per side Bupivicaine 0.5% NEVER USE EPI CONTAINING LOCAL ANESTHETIC Onset: 15-30 min Duration of Anesthetic: 5-15 hours Duration of Analgesic: 6-30 hours

Digital Block:

Digital Block Insert the needle on the dorsolateral base of the finger and direct anteriorly toward the base of the phalanx until the needle contacts the phalanx. Inject 1-2mL of local anesthetic, and inject an additional 1mL while withdrawing the needle back to skin level. The same procedure is repeated on each side of the base of the finger to achieve anesthesia of the entire finger. THE SAME PRINCIPALS APPLY TO BLOCK THE TOES.

Digital Block:

Digital Block Transthecal Digital Block Transthecal block is placed by infusing local anesthetic into the flexor tendon sheath. With the hand supinated, the flexor tendon is located. The needle should enter the skin at a 45 º angel. Inject 2mL of local anesthetic into the flexor tendon sheath at the level of the distal palmar crease.

Digital Block:

Digital Block Resistance to injection indicates the needle is against the tendon. Careful withdrawal of the needle results in free flow of medication as the potential space between the tendon and the sheath is entered. ***Combining both techniques increases the success rate and provides for more extensive distribution of anesthesia.

Intercostobrachial Nerve Block:

Intercostobrachial Nerve Block Cutaneous Nerve Block Blocks of these nerves are often combined with infraclavicular or axillary block to achieve more complete anesthesia of the upper arm. Also used individually to minimize tourniquet pain. A 1½ inch 25-gauge needle is inserted at the level of the axillary fossa. The entire width of the medial aspect of the arm is infiltrated with local anesthetic to raise a subcutaneous “wheal” of anesthesia.

Lower Extremity Blocks:

Lower Extremity Blocks Ankle Femoral

Ankle Block:

Ankle Block Indication: Surgery of the Foot and Toes Needle: 1½ inch Local: 6mL per Nerve Bupivicaine 0.5% NEVER USE EPI CONTAINING LOCAL ANESTHETIC Onset: 15-30 min Duration of Anesthetic: 5-15 hours Duration of Analgesic: 6-30 hours Two Deep Nerves: Posterior Tibial, Deep Peroneal Three Superficial Nerves: Sural, Saphenous, Superficial Peroneal

Ankle Block:

Ankle Block Patient is in supine position with foot elevated on foot rest Posterior Tibial Insert needle in the groove just behind the medial malleolus. Advance until it contacts bone and withdraw 1-2mm Inject 2-3mL anesthetic. A “fan” technique is recommended to increase the success rate. Deep Peroneal Insert needle just lateral to the extensor hallucis longus tendon. Advance until it contact bone and withdraw 1-2mm. Inject 2-3mL anesthetic. A “fan” technique is recommended to increase the success rate.

Ankle Block:

Ankle Block Saphenous Nerve Insert the needle at the level of the medial malleolus and a “ring” of local anesthetic is raised from the point of needle entry to the Achilles tendon and anteriorly to the tibial ridge Inject 6mL local anesthetic Superficial Peroneal Nerve The needle is inserted at the tibial ridge and extended laterally toward the lateral malleolus Inject 5-6mL of local anesthetic, making sure to raise a subcutaneous “wheal” which indicates injection in the proper superficial plane

Ankle Block:

Ankle Block Sural Nerve Insert the needle at the level of the lateral malleolus and the local anesthetic is infiltrated towards the Achilles tendon. Inject 5-6mL of local anesthetic, making sure to raise a subcutaneous “wheal” which indicates injection in the proper superficial plane

Femoral Nerve Block:

Femoral Nerve Block Skill Level: Intermediate Indications: Anterior Thigh and Knee Surgery Landmarks: Femoral Crease, Femoral Artery Pulse Nerve Stimulator: Twitch of the Patella (Quadracep) @ 0.2-0.5 mA Local: 30mL Bupivicaine 0.5% 20mL and Lidocaine 2% with Epi 10mL Onset: 10-20 min Duration of Anesthesia: 5-15 hours Duration of Analgesia: 6-30 hours

Femoral Nerve Block:

Femoral Nerve Block The patient is in the supine position with both legs extended Palpate the femoral artery at the femoral crease, and insert the needle just lateral to the artery and advance in the sagittal, slightly cephalad plane. Set the nerve stimulator to 2.0mA and proper needle position will indicate a visual or palpable twitch of the quadracep muscle (a patella twitch).

Femoral Nerve Block:

Femoral Nerve Block Decrease the nerve stimulation until you continue to have a twitch around 0.2-0.5mA. Inject 25-30mL local anesthetic, aspirating every 5mL

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