Read Morgan and Mikhail's Clinical Anesthesiology, 6th edition PDF Ebook by John F. soundofheaven.infohed by McGraw-Hill Education. Section I: Anesthetic Equipment & Monitors Section IV: Regional Anesthesia & Pain Management Morgan & Mikhail's Clinical Anesthesiology, 6e. DOWNLOAD Morgan and Mikhail's Clinical Anesthesiology, 6th Edition By John F Butterworth IV MD, David C Mackey, John D Wasnick MD [PDF EBOOK EPUB.
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Department of Anesthesia. Texas Tech University Health Sciences Center. School of Medicine. Lubbock, Texas. Morgan & Mikhail's. New York. Morgan and Mikhail's Clinical Anesthesiology PDF 5th Edition It is a must-have book for all anesthesia students/trainees and practitioners. 5th edition | Morgan & Mikhail's CLINICAL ANESTHESIOLOGY John F. xiii 1 The Practice of Anesthesiology 1 section Anesthetic Equipment & Monitors 2 The Operating Available at: soundofheaven.info Appendix_L. pdf.
Context-sensitive half-time and anesthesia: Nonoperating Room. Anesthesiologist's Manual of Surgical Procedures. The International Edition is not available in North America. Pharmacokinetic models can range from entirely empirical dose versus response relationships to mechanistic models of ligand—receptor binding.
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Mackey ,John D. Wasnick Pages: Paperback Brand: At the same time it has retained its value for coursework, review, or as a clinical refresher. This Sixth Edition has been extensively revised to reflect a greater emphasis on critical care medicine, enhanced recovery, and ultrasound in anesthesia practice. Key features that make it easier to understand complex topics: If you want to download this book, click link in the next page 5.
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The complex process of drug distribution into and out of tissues is one reason that half-lives are clinically useless. Charged molecules are able to pass in small quantities into most organs. The free concentration equilibrates between organs and tissues. When the plasma concentration exceeds the concentration in tissue. The time course of distribution of drugs into peripheral tissues is complex and can only be assessed with computer models.
Permeation of the central nervous system by ionized drugs is limited by pericapillary glial cells and endo2 thelial cell tight junctions. If the drug is highly bound in tissues. Albumin binds many acidic drugs eg. When the plasma concentration is less than the concentration in tissue.
The redistribution phase for each tissue follows this moment of equilibration. The equilibrium concentration in an organ relative to blood depends only on the relative solubility of the drug in the organ relative to blood. During redistribution. Molecules in blood are either free or bound to plasma proteins and lipids.
Trauma including surgery. Following prolonged infusions. Distribution is a major determinant of endorgan drug concentration. The context-sensitive decrement time is a more generalized concept referring to any clinically relevant decreased concentration in any tissue, particularly the brain or effect site. This volume is calculated by dividing a bolus dose of drug by the plasma concentration at time 0. However, the typical anesthetic drug is lipophilic, resulting in a Vdss that exceeds total body water approximately 40 L.
For example, the Vdss for fentanyl is about L in adults, and the Vdss for propofol may exceed L. Vdss does not represent a real volume but rather reflects the volume into which the drug would need to distribute to account for the observed plasma concentration given the dose that was administered. The concept of a single Vd does not apply to any intravenous drugs used in anesthesia. All intravenous anesthetic drugs are better modeled with at least two compartments: The behavior of many of these drugs is best described using three compartments: The central compartment may be thought of as including the blood and any ultra-rapidly equilibrating tissues such as the lungs.
The peripheral compartment is composed of the other body tissues. For drugs with two peripheral compartments, the rapidly equilibrating compartment comprises the organs and muscles, while the slowly equilibrating compartment roughly represents distribution of the drug into fat and skin. These compartments are designated V1 central , V2 rapid distribution , and V3 slow distribution.
The volume of distribution at steady state, Vdss is the algebraic sum of these compartment volumes. V1 is calculated by the above equation showing the relationship between volume, dose, and concentration. The other volumes are calculated through pharmacokinetic modeling. A small Vdss implies that the drug has high aqueous solubility and will remain largely within the intravascular space. For example, the Vdss of.
The exception is esters, which undergo hydrolysis in the plasma or tissues. The end products of biotransformation are often but not necessarily inactive and water soluble. Water solubility allows excretion by the kidneys. Metabolic biotransformation is frequently divided into phase I and phase II reactions.
Phase I reactions convert a parent compound into more polar metabolites through oxidation, reduction, or hydrolysis. Phase II reactions couple conjugate a parent drug or a phase I metabolite with an endogenous substrate eg, glucuronic acid to form watersoluble metabolites that can be eliminated in the urine or stool. Although this is usually a sequential process, phase I metabolites may be excreted without undergoing phase II biotransformation, and a phase II reaction can precede or occur without a phase I reaction.
Hepatic clearance is the volume of blood or plasma whichever was measured in the assay cleared of drug per unit of time. The units of clearance are units of flow: Clearance may be expressed in milliliters per minute, liters per hour, or any other convenient unit of flow. If every molecule of drug that enters the liver is metabolized, then hepatic clearance will equal liver blood flow. This is true for very few drugs, although it is very nearly the case for propofol. For most drugs, only a fraction of the drug that enters the liver is removed.
The fraction removed is called the extraction ratio. The hepatic clearance can therefore be expressed as the liver blood flow times the.
The clearance of drugs efficiently removed by the liver ie, having a high hepatic extraction ratio is proportional to hepatic blood flow. For example, because the liver removes almost all of the propofol that goes through it, if the hepatic blood flow doubles, then the clearance of propofol doubles.
Induction of liver enzymes has no effect on propofol clearance, because the liver so efficiently removes all of the propofol that goes through it. Even severe loss of liver tissue, as occurs in cirrhosis, has little effect on propofol clearance.
Drugs such as propofol have flow-dependent clearance. Many drugs have low hepatic extraction ratios and are slowly cleared by the liver. For these drugs, the rate-limiting step is not the flow of blood to the liver, but rather the metabolic capacity of the liver itself. Changes in liver blood flow have little effect on the clearance of such drugs. However, if liver enzymes are induced, then clearance will increase because the liver has more capacity to metabolize the drug.
Conversely, if the liver is damaged, then less capacity is available for metabolism and clearance is reduced. Drugs with low hepatic extraction ratios thus have capacity-dependent clearance. Occasionally metabolites excreted in bile are subsequently converted back to the parent drug.
For example, lorazepam is converted by the liver to lorazepam glucuronide. Compartment Models Multicompartment models provide a mathematical framework that can be used to relate drug dose to changes in drug concentrations over time. Conceptually, the compartments in these models are tissues with a similar distribution time course. For example, the plasma and lungs are components of the central compartment. The organs and muscles, sometimes called the vessel-rich group, could be the second, or rapidly equilibrating, compartment.
Fat and skin have the capacity to bind large quantities of lipophilic drug but are poorly perfused. These could represent the third, or slowly equilibrating, compartment. This is an intuitive definition of compartments, and it is important to recognize that the compartments of a pharmacokinetic model are mathematical abstractions that relate dose to observed concentration. A one-to-one relationship does not exist between any compartment and any organ or tissue in the body.
Many drugs used in anesthesia are well described by a two-compartment model. This is generally the case if the studies used to characterize the pharmacokinetics do not include rapid arterial sampling over the first few minutes Figure 7—1.
Without rapid arterial sampling the ultra-rapid initial drop in plasma concentration immediately after a bolus injection is missed, and the central compartment volume is blended into the rapidly equilibrating compartment. When rapid arterial sampling is used in pharmacokinetic experiments, the results are generally a three-compartment model.
In these cases the number of identifiable compartments is a function of the experimental design and not a characteristic of the drug. In compartmental models the instantaneous concentration at the time of a bolus injection is assumed to be the amount of the bolus divided by the central compartment volume. This is not. Excretion Some drugs and many drug metabolites are excreted by the kidneys. Renal clearance is the rate of elimination of a drug from the body by kidney excretion.
This concept is analogous to hepatic clearance, and similarly, renal clearance can be expressed as the renal blood flow times the renal extraction ratio. The nonionized uncharged fraction of drug is reabsorbed in the renal tubules, whereas the ionized charged portion is excreted in urine. The fraction of drug ionized depends on the pH; thus renal elimination of drugs that exist in ionized and nonionized forms depends in part on urinary pH.
The kidney actively secretes some drugs into the renal tubules.
Many drugs and drug metabolites pass from the liver into the intestine via the biliary system. During the distribution phase, the drug moves from the central compartment to the peripheral compartment. The elimination phase consists of metabolism and excretion. Instead, drug returns to the plasma from the rapidly equilibrating compartment.
The reversed role of the rapidly equilibrating tissues from extracting drug to returning drug accounts for the slower rate of decline in plasma concentration in this intermediate phase. Eventually there is an even slower rate of decrease in plasma concentration, which is log-linear until the drug is completely eliminated from the body. This terminal log-linear phase occurs after the slowly equilibrating compartment shifts from net removal of drug from the plasma to net return of drug to the plasma.
The mathematical models used to describe a drug with two or three compartments are, respectively: Drugs described by two-compartment and three-compartment models will have two or three half-lives. Each half-life is calculated as the natural log of 2 0. The coefficients A, B, and C represent the contribution of each of the exponents to the overall decrease in concentration over time.
The two-compartment model is described by a curve with two exponents and two coefficients, whereas the three-compartment model is described by a curve with three exponents and three coefficients. The mathematical relationships among compartments, clearances, coefficients, and exponents are complex.
Every coefficient and every exponent is a function of every volume and every clearance. For drugs described by multicompartment pharmacokinetics. If the bolus is given over a few seconds, the instantaneous concentration is 0, because the drug is all in the vein, still flowing to the heart. It takes only a minute or two for the drug to mix in the central compartment volume. This misspecification is common to conventional pharmacokinetic models. More physiologically based models, sometimes called front-end kinetic models, can characterize the initial delay in concentration.
These models are useful only if the concentrations over the first few minutes are clinically important. After the first few minutes, front-end models resemble conventional compartmental models. In the first few minutes following initial bolus administration of a drug, the concentration drops very rapidly as the drug quickly diffuses into peripheral compartments. The decline is typically an order of magnitude over 10 minutes.
For drugs with very rapid hepatic clearance eg, propofol or those that are metabolized in the blood eg, remifentanil , metabolism contributes significantly to the rapid initial drop in concentration. Following this very rapid drop there is a period of slower decrease in plasma concentration. During this period, the rapidly. This fundamental concept in the exposure versus response relationship is captured graphically by plotting exposure usually dose or concentration on the x axis as the independent variable.
The shape of the relationship is typically sigmoidal. The context-sensitive half-time. This does not mean that recovery from alfentanil will be faster. Depending on the circumstances. The fundamental pharmacodynamic concepts are captured in the relationship between exposure to a drug and physiological response to the drug. Pharmacokinetic models can range from entirely empirical dose versus response relationships to mechanistic models of ligand—receptor binding.
Computer models readily demonstrate that recovery from an infusion lasting several hours will be faster when the drug administered is sufentanil than it will be when the infused drug is alfentanil.
For our purposes here. For a drug such as sodium nitroprusside. C50 is the concentration associated with half-maximal effect. Drugs lacking potency have a high C Once defined in this fashion. For the first equation. Highly efficacious drugs have a large maximum physiological effect. Emax will equal E0. C50 is a measure of drug potency. The right side is also flat. C is the concentration. Emax is the maximum physiological measurement.
For drugs that lack efficacy. A sigmoidal curve is required to connect the baseline to the asymptote. Because of the risk of ventilatory and cardiovascular depression even at concentrations only slightly greater than those producing anesthesia. Pmax is the maximum probability. C is drug concentration. A In this case. As before. E0 is the baseline effect in the absence of drug. Emax is the maximum change from baseline. This range can be measured either between two different points on the same concentration versus response curve.
The therapeutic index is the C50 for toxicity divided by the C50 for the desired therapeutic effect. In the second equation. Emax is related to the intrinsic efficacy of a drug. The curve described above represents the relationship of drug concentration to a continuous physiological response. The therapeutic window for a drug is the range between the concentration associated with a desired therapeutic effect and the concentration associated with a toxic drug response.
Highly potent drugs have a low C Chap 2. Applied Clinical Pharmacokinetics. Keifer J. Noncompetitive antagonism occurs when the antagonist.
The drug effect is governed by the fraction of receptors that are occupied by an agonist. Like the concentration versus response curve. Because the rate of formation at steady state is 0.
Pharmacological antagonists reverse the effects of the agonist but do not otherwise exert an effect of their own. Glass P: Context-sensitive half-time and anesthesia: How does theory match reality? Curr Opin Anaesthesiol Yu AB.
Shargel L. That fraction is based on the concentration of the drug. If the binding of an endogenous ligand is chronically blocked. According to the law of mass action. If we define f. Wu-Pong S Eds: Receptor occupancy is only the first step in mediating drug effect. The rate constant koff defines the rate of ligand unbinding from the receptor. Brunton LL. Chaps 1. The rate constant kon defines the rate of ligand binding to the receptor. Chabner BA. Maximal drug effect could occur at very low receptor occupancy.
Binding of the drug to the receptor can trigger a myriad of subsequent steps. Competitive antagonism occurs when the antagonist competes with the agonist for the binding site. Knollman BC Eds: This binding is described by the law of mass action. Local anesthetic may be deposited at any point along the brachial plexus. Brachial plexus block at the level of the cords provides excellent anesthesia for procedures at or distal to the elbow. Complete anesthesia of the knee can be attained with a proximal sciatic nerve block.
In addition to potent analgesia. As with other brachial plexus blocks. A femoral nerve block alone will seldom provide surgical anesthesia. Regional anesthetics should be administered in an area where standard hemodynamic monitors.
A properly performed interscalene block invariably blocks the ipsilateral phrenic nerve. Terminal nerves may be anesthetized anywhere along their course. The upper arm and shoulder are not anesthetized with this approach. Intravenous regional anesthesia. Often it is necessary to anesthetize a single terminal nerve.
From the paresthesia-seeking techniques described by Winnie in the mid-twentieth century. An understanding of regional anesthesia anatomy and techniques is required of the well-rounded anesthesiologist. The risk—benefit ratio often favors regional anesthesia in patients with multiple comorbidities for whom a general anesthetic carries a greater risk.
Although anatomic relationships have not changed over time. In addition. Patients with chronic pain and opioid tolerance may receive optimal analgesia with a continuous peripheral nerve block so-called perineural local anesthetic infusion.
The field of regional anesthesia has accordingly expanded to one that addresses not only the intraoperative concerns of the anesthesiologist. All sciatic nerve blocks fail to provide complete anesthesia for the cutaneous medial leg and ankle joint capsule.
A comprehensive knowledge of anatomy and an understanding of the planned surgical procedure are. Placement of a block needle through a site of infection can theoretically track infectious material into the body.
Supportive measures should begin immediately. Examples include younger pediatric patients and some developmentally delayed individuals. Positioning should be ergonomically favorable for the practitioner and comfortable for the patient. Site-specific risks should also be considered for each individual patient. In the event of a local anesthetic toxic reaction. Bleeding disorders and pharmacological anticoagulation heighten the risk of local hematoma or hemorrhage.
Specific peripheral nerve block locations warranting the most concern are posterior lumbar plexus and paravertebral blocks owing to their relative proximity to the retroperitoneal space and neuraxis. If possible. Individuals with a preexisting condition eg. Intravenous premedication should be employed to allay anxiety and minimize discomfort.
Although nerve injury is always a possibility with a regional anesthetic. Patients should be monitored with pulse oximetry. A relatively short-acting benzodiazepine and opioid are most often used and should be titrated for comfort while ensuring that patients respond to verbal cues. The precise mechanisms have yet to be clearly defined but may involve local ischemia from high injection pressure or vasoconstrictors. Potential for toxicity should be considered.
Other risks associated with regional anesthesia include local anesthetic toxicity from intravascular injection or perivascular absorption. Indwelling perineural catheters can serve as a nidus of infection. Sterile technique should be strictly observed. A detailed discussion of local anesthetics is provided elsewhere see Chapter In a patient with severe pulmonary compromise or hemidiaphragmatic paralysis.
Nerve Stimulation Technique For this technique. Field blocks are used commonly by surgeons to minimize incisional pain and may be used as a supplementary technique or as a sole anesthetic for minor. Anesthesiologists often use field blocks to anesthetize the superficial cervical plexus for procedures involving the neck or shoulder.
Field blocks may be undesirable in cases where they obscure the operative anatomy. Paresthesia Technique Formerly the mainstay of regional anesthesia. When the insulated needle is placed in. When a needle makes direct contact with a sensory nerve. Using known anatomic relationships and surface landmarks as a guide. A grounding electrode is attached to the patient to complete the circuit Figure 46—2. A curvilinear probe provides better penetration with lower resolution.
Depending on the amplitude of signal received. Ultrasound uses high-frequency 1—20 MHz sound waves emitted from piezoelectric crystals that travel at different rates through tissues of different densities. The optimal transducer varies depending upon the depth of the target nerve and approach angle of the needle relative to the transducer Figure 46—3. In contrast. The degree of efficiency with which sound passes through a substance determines its echogenicity. Structures and substances through which sound passes easily are described as hypoechoic and appear dark or black on the ultrasound screen.
Ultrasound Technique Ultrasound for peripheral nerve localization is becoming increasingly popular. Although it is common to redirect the block needle until muscle contractions occur at a current less than 0. In an attempt to further minimize any induced motor block. Local anesthetic is the primary medication infused. Potential advantages appear to depend on successfully improving analgesia and include reductions in resting and dynamic pain. There are many types of catheters. In some cases patient satisfaction.
Nerves are best imaged in cross-section. Longacting local anesthetics eg. Unlike nerve stimulation alone. Lowfrequency transducers provide an image of poorer quality but have better tissue penetration and are therefore used for deeper structures. This technique usually results in a far lower injected volume of local anesthetic 10—30 mL. Transducers with a linear array offer an undistorted image and are therefore often the first choice among practitioners.
The local anesthetic may be administered exclusively as repeated bolus doses or a basal infusion. As with all medical procedures. Unlike single-injection peripheral nerve blocks. Using a small. As the trunks pass over the lateral border of the first rib. As the nerve roots leave the intervertebral foramina. Serious complications. The three distinct trunks formed between the anterior and middle scalene muscles are termed superior.
Contributions from C4 and T2 are often minor or absent. Interscalene Block An interscalene brachial plexus block is indicated for procedures involving the shoulder and upper arm Figure 46—8. The hemidiaphragmatic paresis may result in. As the brachial plexus emerges below the clavicle. Roots C5—7 are most densely blocked with this approach. At the lateral border of the pectoralis minor muscle. For complete surgical anesthesia of the shoulder. The lateral cord gives off the lateral branch of the median nerve and terminates as the musculocutaneous nerve.
A properly performed interscalene block invariably blocks the ipsilateral phrenic nerve completely for nerve stimulation techniques. Contraindications to an interscalene block include local infection. Recurrent laryngeal nerve involvement often induces hoarseness. Having the patient lift and turn the head against resistance often helps delineate the. The brachial plexus passes between the anterior and middle scalene muscles at the level of the cricoid cartilage. In a patient with contralateral vocal cord paralysis.
Other site-specific risks include vertebral artery injection suspect if immediate seizure activity is observed. The interscalene groove should not be confused with the groove between the sternocleidomastoid and the anterior scalene muscle.
The external jugular vein often crosses the interscalene groove at the level of the cricoid cartilage. Even 1 mL of local anesthetic delivered into the vertebral artery may induce a seizure. The ventral rami of C5—C8 and T1 form the brachial plexus.
The interscalene groove is palpated using the nondominant hand. If surgical anesthesia is desired for the entire shoulder. If bone transverse process is contacted. For an out-of-plane technique. After the skin is anesthetized. A motor response of the diaphragm indicates that the needle is placed in too anterior a direction.
After careful aspiration for nonappearance of blood. Aspiration of arterial blood should raise concern for vertebral or carotid artery puncture. Nerve Stimulation A relatively short 5-cm insulated needle is usually employed. For both techniques. Figure 46— The brachial plexus and anterior and middle scalene muscles should be visualized in cross-section Figure 46— The carotid artery and internal jugular vein may be seen lying anterior to the anterior scalene muscle.
The brachial plexus at this level appears as three to five hypoechoic circles. Interscalene perineural infusions provide potent analgesia following shoulder surgery.
Ultrasound A needle in-plane or out-of-plane technique may be used. Sparing of distal branches. For an in-plane technique. It may be helpful to have the patient turn slightly laterally with the affected side up to facilitate manipulation of the needle. It has seen a resurgence in recent years as the use of ultrasound guidance has theoretically improved safety.
Ultrasound image of the brachial plexus in the interscalene groove. A longer block needle 8 cm is usually necessary. The supraclavicular block does not reliably anesthetize the axillary and suprascapular nerves. Depending on visualized spread relative to the target nerve s. The needle tip and shaft should be visualized during the entire block performance. Supraclavicular perineural catheters provide inferior analgesia compared with infraclavicular infusion and are often displaced due to a lack of muscle mass to aid catheter retention.
Light blue shading indicates regions of variable blockade. The first rib should also be identified as a hyperechoic line just deep to the artery. The subclavian artery should be easily identified. The brachial plexus appears as multiple hypoechoic disks just superficial and lateral to the subclavian artery Figure 46— After careful aspiration for the nonappearance of blood. A linear. Ultrasound image of the brachial plexus in the supraclavicular fossa. Pneumothorax and subclavian artery puncture.
Ultrasound The patient should be supine with the head turned 30o toward the contralateral side. The skin is anesthetized. Pleura may be identified adjacent to the rib.
The needle is inserted lateral to the transducer in a direction parallel to the ultrasound beam. Nearly half of patients undergoing supraclavicular block will experience ipsilateral phrenic nerve palsy. Abducting the arm 90o improves axillary artery imaging.
The axilla is also a suboptimal site for perineural catheter placement because of greatly inferior analgesia versus an infraclavicular infusion. Infraclavicular Block cords provides excellent anesthesia for procedures at or distal to the elbow Figure 46— Optimal needle positioning is between the axillary artery and the posterior cord.
The axillary artery pulse should be palpated and its location marked as a reference point. At this level. The subclavian artery and brachial plexus run deep to the coracoid process and can be found approximately 2 cm medial and 2 cm caudad to it. A relatively long needle is inserted 2—3 cm cephalad to the transducer. Axillary Block At the lateral border of the pectoralis minor muscle. Local infection. Local anesthetic spread should be visualized surrounding the plexus after careful aspiration and incremental injection.
The axillary. All of the numerous axillary block techniques require the patient to be positioned supine. Ultrasound With the patient in the supine position. There are few contraindications to axillary brachial plexus blocks.
As the brachial plexus traverses beyond the first rib and into the axilla. Site-specific risks of the infraclavicular approach include vascular puncture and pneumothorax although less common than with supraclavicular block. It is often prudent to avoid this approach in patients with vascular catheters in the subclavian region. Insertion of a perineural catheter should always be in the same location posterior to the axillary artery.
The axillary artery and vein are identified in crosssection Figure 46—18B. The medial. Nerve Stimulation The patient is positioned supine with the head turned to the contralateral side. Because the axilla is highly vascularized. A high-frequency linear transducer will. Three randomized. An acceptable motor response is finger flexion or extension at a current less than 0. Use a small curvilinear probe in a parasagittal plane to visualize the brachial plexus.
Ultrasound image of the brachial plexus surrounding the axillary artery. The red dot indicates the location of local anesthetic deposition. A total of 30—40 mL of local anesthetic is typically used.
Once an acceptable muscle response is identified. Although a single injection of 40 mL may be used. Axillary n.. Medial brachial cutaneous n. The musculocutaneous nerve elbow flexion is separate and deep within the coracobrachialis muscle. The needle is then slightly advanced until blood aspiration ceases.
Injection can be performed posteriorly. With the arm abducted and externally rotated. Nerve Stimulation Again the nondominant hand is used to palpate and immobilize the axillary artery. Transarterial Technique This technique has fallen out of favor due to the trauma of twice purposefully penetrating the axillary artery along with a theoretically increased risk of inadvertent intravascular local anesthetic injection.
A 2-in. The nondominant hand is used to palpate and immobilize the axillary artery. Musculocutaneous n. Radial n. Axillary v. Median n. Subcutaneous tissue Skin Intercostobrachial n.
Coracobrachialis m. Brachial plexus Ulnar n. Triceps m. Axillary a. Patient positioning and needle angle for axillary brachial plexus block. Biceps m. Ten milliliters of local anesthetic is then injected around each nerve including the musculocutaneous.
It enters the arm and runs just medial to the brachial artery Figure 46— As it enters the antecubital space. Ultrasound Using a high-frequency linear array ultrasound transducer. Brachial a. The needle is inserted superior lateral to the transducer and advanced inferiorly medially toward the plexus under direct visualization.
Median Nerve Block The median nerve is derived from the lateral and medial cords of the brachial plexus. Biceps tendon C. Just distal to this point. The brachial plexus can be identified surrounding the artery Figure 46— Flexor carpi radialis Palmaris longus Flexor digitorum superficialis Flexor digitorum profundus Palmar branch Palmar digital nerves Blocks of the Terminal Nerves minal nerve.
Axillary artery. Brachioradialis m. A short gauge needle is inserted just medial and deep to the palmaris longus tendon.
If ultrasound is used. To block the median nerve at the wrist. Brachialis m. Skin Subcutaneous tissue Biceps m. At the level of the proximal wrist flexion crease. To block the median nerve at the elbow. To block the ulnar nerve at the level of the elbow. With ultrasound. The nerve is frequently palpable just proximal to the medial epicondyle. Ulnar n. Ulnar Nerve Block The ulnar nerve is the continuation of the medial cord of the brachial plexus and maintains a position medial to the axillary and brachial arteries in the upper arm Figure 46— Medial epicondyle Arcuate ligament Ulnar a.
The needle is inserted just medial to the artery Figure 46—29 and 3—5 mL of local anesthetic is injected. At the distal third of the humerus.
To block the ulnar nerve at the wrist. At the wrist. Flexor carpi ulnaris Biceps tendon Flexor digitorum profundus Palmar branch Dorsal branch Palmar retinaculum Median n. In the mid-forearm.
Flexor carpi radialis m.
Radial a. Ulnar a. To block the radial nerve at the elbow. A short gauge insulated needle is inserted just lateral to the tendon and directed toward the lateral.
Terminal sensory branches include the lateral cutaneous nerve of the arm and the posterior cutaneous nerve of the forearm. After exiting the spiral groove as it approaches the lateral epicondyle.
The deep branch remains close to the periosteum and innervates the postaxial extensor group of the forearm. Radial Nerve Block The radial nerve—the terminal branch of the posterior cord of the brachial plexus—courses posterior to the humerus. The superficial branch becomes superficial and follows the radial artery to innervate the radial aspects of the dorsal wrist and the dorsal aspect of the lateral three digits and half of the fourth. The musculocutaneous nerve is the terminal branch of the lateral cord and the most proximal of the major nerves to emerge from the brachial plexus Figure 46— Lateral Brachialis m.
Musculocutaneous Nerve Block A musculocutaneous nerve block is essential to complete the anesthesia for the forearm and wrist and is commonly included when performing the axillary block.
Medial Biceps Median n. Using a short gauge needle. This nerve innervates the biceps and brachialis muscles and distally terminates as the lateral antebrachial cutaneous nerve.
Lateral epicondyle Radial n.
Dorsal Palmar. Deep branch Posterior interosseous n. Lateral epicondyle Flexor carpi radialis m. Superficial branch epicondyle Figure 46—31 until wrist or finger extension is elicited. Ultrasound may be used at the level of the wrist or mid-forearm to identify the radial nerve just lateral to the radial artery.
Sensory innervation of each finger is provided by four small digital nerves that enter each digit at its base in each of the four corners Figure 46— The insertion of the biceps tendon is identified.
Digital Nerve Blocks Digital nerve blocks are used for minor operations on the fingers and to supplement incomplete brachial plexus and terminal nerve blocks. Ultrasound may be used to confirm the location of the musculocutaneous nerve in the coracobrachialis muscle or between this muscle and the biceps see Figure 46— Simple infiltration may be used. A small-gauge needle is inserted at the medial and lateral aspects of the base of the selected digit.
The extremity is elevated and exsanguinated by tightly wrapping an Esmarch elastic bandage from a distal to proximal direction. It supplies cutaneous innervation to the medial aspect of the proximal arm and is not anesthetized with a brachial plexus block Figure 46— An 8 Intravenous regional anesthesia.
Intercostobrachial Nerve Block The intercostobrachial nerve originates in the upper thorax T2 and becomes superficial on the medial upper arm. Anesthesia is usually established after 5—10 min. Patients usually tolerate the distal tourniquet for an additional 15—20 min because it is inflated over an anesthetized area.
Addition of a vasoconstrictor epinephrine has been claimed to seriously compromise blood flow to the digit. Tourniquet pain usually develops after 20—30 min. The proximal tourniquet is inflated. The patient should be supine with the arm abducted and externally rotated. Even Intravenous Regional Anesthesia a Bier block.
Starting at the deltoid prominence and proceeding inferiorly. Three major nerves from the lumbar plexus make contributions to the lower limb: Femoral Nerve Block The femoral nerve innervates the main hip flexors. The posterior femoral cutaneous nerve S1—3. These provide motor and sensory innervation to the anterior portion of the thigh and sensory innervation to the medial leg. The posterior thigh and most of the leg and foot are supplied by the tibial and peroneal portions of the sciatic nerve.
It lies within the psoas muscle with branches descending into the proximal thigh. Slow deflation is also recommended to provide an additional margin of safety. The sacral plexus arises from L4—5 and S1—4. The lumbar plexus is formed by the ventral rami of L1—4. The term 3-in-1 block refers to anesthetizing the femoral.
A femoral nerve block alone. Femoral nerve blocks have a relatively low rate of complications and few contraindications. Its most medial branch is the saphenous nerve. Just lateral to the artery and deep to the fascia iliaca.
Fascia Iliaca Technique The goal of a fascia iliaca block is similar to that of a femoral nerve block. Without use of a nerve stimulator or ultrasound machine. The femoral artery and femoral vein are visualized in cross-section. The needle is advanced through the sartorius muscle. Nerve Stimulation With the patient positioned supine. The needle is inserted parallel to the ultrasound transducer just lateral to the outer edge. The needle is advanced until it is seen penetrating the fascia iliaca.
Local anesthetic is injected. Once the inguinal ligament and femoral artery pulse are identified.
Ultrasound A high-frequency linear ultrasound transducer is placed over the area of the inguinal crease parallel to the crease itself. As the needle passes through the two layers of fascia in this region fascia lata and fascia iliaca.
A short gauge block needle is inserted and directed laterally. A field block is performed with 10—15 mL of local anesthetic.
Once the needle has passed through the fascia iliaca. The lateral femoral cutaneous nerve L2—3 departs from the lumbar plexus. This block usually anesthetizes both the femoral nerve and lateral femoral cutaneous nerves. As there are few vital structures in proximity to the lateral femoral cutaneous nerve.
It may be anesthetized as a supplement to a femoral nerve block or as an isolated block for limited anesthesia of the lateral thigh. Sartorius muscle. Ultrasound image of the femoral nerve. It emerges inferior and medial to the anterior superior iliac spine to supply the cutaneous sensory innervation of the lateral thigh. Lateral Femoral Cutaneous Nerve Block The lateral femoral cutaneous nerve provides sensory innervation to the lateral thigh see Figure 46— The patient is positioned supine or lateral.
Two centimeters distal to the junction of the middle and outer thirds. After identification of the pubic tubercle.
Redirecting laterally and caudally. The obturator nerve contributes sensory branches to the hip and knee joints. This nerve exits the pelvis and enters the medial thigh through the obturator foramen. Obturator Nerve Block A block of the obturator nerve is usually required for complete anesthesia of the knee and is most often performed in combination with femoral and sciatic nerve blocks for this purpose. Posterior Lumbar Plexus Psoas Compartment Block surgical procedures involving areas innervated by the femoral.
Following careful aspiration for the nonappearance of blood. These include 10 Posterior lumbar plexus blocks are useful for. The needle is advanced posteriorly until bone is contacted Figure 46— Obturator n. Femoral nerve. Femoral n. Contact pubic tubercle 1. The midline is palpated. A long The posterior superior iliac spine is then palpated and a line is drawn cephalad.
Modern posterior lumbar plexus blocks deposit local anesthetic within the body of the psoas muscle. The needle is advanced in an anterior direction until a femoral motor response is elicited quadriceps contraction. If available. Lumbar plexus Spinal cord procedures on the hip. The patient is positioned in lateral decubitus with the side to be blocked in the nondependent position Figure 46— The lumbar plexus is relatively close to multiple sensitive structures Figure 46—48 and reaching it requires a very long needle.
Lumbar nerve roots emerge into the body of the psoas muscle and travel within the muscle compartment before exiting as terminal nerves see Figure 46— A line is first drawn through the lumbar spinous processes. If the transverse process is contacted. Saphenous Nerve Block The saphenous nerve is the most medial branch of the femoral nerve and innervates the skin over the medial leg and the ankle joint see Figure 46—