By E. Malir. College of Charleston.
Journal of muscle spindle sensitivity to movement during reinforce- Physiology (London) discount desyrel 100 mg on-line anxiety tips, 218 generic desyrel 100 mg with amex anxiety symptoms of flu, 405–31. Muscle spindle afferent discharge from resting and Physiology (London), 523, 271–82. Kinaesthetic role of muscle affer- Developments in Electromyography and Clinical Neuro- ents in man, studied by tendon vibration and microneuro- physiology,vol. Human muscle spindle discharge during isometric ceptive messages induced by tendon vibration in man: a voluntary contractions. Human muscle spindle prioceptive population coding of two-dimensional limb response in a motor learning task. Developments in Electromyography and Clinical Neuro- Motorcontrolinhumanswithlarge-ﬁbersensoryneuropa- physiology,vol. Brain discharge of human spindle afferents following voluntary Research, 543, 97–101. Fusimotor activity and the tendon jerk in the after a unilateral stroke. Neuroscience Letters, 264, 109– of muscle spindle discharge on the human H reﬂex and 12. After reciprocal Ia inhi- bition, the recurrent pathway was the ﬁrst pathway for which a reliable selective method of investiga- General features tion became available for use in human subjects. This is due to the simplicity of its organisation and Morphology to its unique feature of being activated by the ﬁnal Renshaw cells are funicular cells located ventrally motor output rather than by a special afferent input. The organisation of the disynaptic Background from recurrent pathway animal experiments Some relevant connections are sketched in Fig. Renshaw (1941) demonstrated that, in animals with dorsal roots sectioned, antidromic impulses in Pharmacology motoraxonscouldevokeashort-latencylong-lasting inhibition of the monosynaptic reﬂex in homony- Recurrent collaterals excite Renshaw cells using mous and synergistic motoneurones. The inhibition acetylcholine as the transmitter, much as do moto- depends on motor axon recurrent collaterals activa- neurone terminals at the neuromuscular junction ting interneurones, that have been called Renshaw (Eccles, Fatt & Koketsu, 1954). This characteristic cells, the discharge of which inhibits motoneu- provides the unique possibility in human studies rones (Eccles, Fatt & Koketsu, 1954). The following of studying transmission through the pathway by description of the recurrent pathway in the cat (see altering it pharmacologically. Group Ia afferent Strength of recurrent inhibition Ia inhibitory Conﬂicting results have been reported. Lindsay & interneurone Binder (1991) found a very low gain, which con- tradicted older results (Granit & Renkin, 1961). Wiring diagram of the connections of the recurrent of extensive overlap; see Hultborn et al. In this and subsequent ﬁgures, excitatory synapses are represented by Y-shape bars, inhibitory synapses by small ﬁlled circles, and inhibitory interneurones Input–output relationship by larger ﬁlled circles. Renshaw cells, their axons and their inhibitory projections are in grey. An individual Renshaw InindividualRenshawcellstherelationshipbetween cell activated by the recurrent collateral from an extensor the amount of injected current and the number of motoneurone (MN) has inhibitory projections to spikes produced by the cell is sigmoid (Hultborn & motoneurones of this pool (and MNs of synergistic muscles, Pierrot-Deseilligny, 1979b). The output from the not represented), on MNs of the same muscle(s), on Ia Renshaw cell pool caused by a phasic motor volley inhibitory interneurones which are activated by Ia afferents from the extensor muscle and inhibit antagonistic ﬂexor MNs, may be therefore facilitated when Renshaw cells and on Renshaw cells activated from ﬂexor MNs. Group II receive a tonic excitatory input sufﬁcient to move afferents inhibit Renshaw cells disynaptically. Descending them to the steeply rising phase of the input-output tracts elicit both excitation and inhibition of Renshaw cells. There is the same transmitter, acetylcholine (Ach), at the neuromuscular junction and at the synapse between recurrent collaterals and Renshaw cells. From data in Baldissera, Input to Renshaw cells Hultborn & Illert (1981). Input from motoneurones In the cat hindlimb, recurrent collaterals are always Electrophysiology given off by motoneurones innervating ankle and Asinglevolleyin motoraxonsproducesarepetitive knee muscles but are absent from motoneurones discharge of Renshaw cells, due to a prolonged EPSP of short plantar foot muscles (Cullheim & Kellerth, from the recurrent collaterals. Similarly,recurrentcollateralsareabsentfrom imal recurrent IPSP in motoneurones from a given motoneurones of long digit extensors in the cat heteronymous nerve (i. Motor stimulation of all motor axons in the nerve) has a axon collaterals spread a distance of less than centrallatencyofslightlymorethan1ms(disynaptic 1mmfrom their parent cell body, so that excitation pathway), reaches its maximum 5 ms after its onset, of a given Renshaw cell can be obtained only from Background from animal experiments 153 motor nuclei located in the immediate neighbour- activity, thus de-coupling Renshaw cells from their hood (Cullheim & Kellerth, 1978). Renshaw cell is excited by axon collaterals of many motoneurones, as evidenced both by their smoothly growing response to increasing intensity of stimu- Projections of Renshaw cells lation of individual nerves and by their excitation from several nerves (Eccles, Fatt & Koketsu, 1954; Projections to motoneurones Ecclesetal. Renshawcellsareexcitedmainly Following activation of the motoneurones of a given by motoneurones of synergistic muscles and not by muscle,recurrentinhibitionisevokedinanumberof those of strict antagonists, and this indicates that motor nuclei.
Nurses are Like other rehabilitationists purchase desyrel 100mg line anxiety tips, PTs have in- also in an ideal position to get patients to com- creasingly sought strategies to improve the ac- ply with lifestyle changes for disease preven- curacy and reproducibility of clinical evalua- tion buy desyrel 100mg cheap anxiety symptoms shortness of breath. Two broad physician, psychologist, and social worker, they categories of exercise programs, therapeutic can initiate discussions about drug abuse with exercise and the so-called neurophysiologic young patients on a TBI or SCI unit. For new and neurodevelopmental approaches, have re- medication that will be used after hospital dis- ceived the most attention in the past. Newer charge, nurses can develop cues and rituals concepts related to neuroplasticity, motor con- with the patient and caregiver that reinforce trol, and how motor skills are learned are merg- compliance. The Association of Rehabilitation from the dynamic interplay between multiple Nurses has excellent resources for continuing CNS, peripheral, and biomechanical systems education (www. Practices in Physical and Occupational Therapy Therapeutic exercise and reeducation Massed practice Neurofacilitation techniques Biofeedback Proprioceptive neuromuscular facilitation Virtual environment training Bobath Musculoskeletal techniques Brunnstrom Rood Electromyogram-triggered neuromuscular stimulation Motor skills learning Orthotics and assistive devices Task-oriented practice Forced use 220 Common Practices Across Disorders constrained by the environment. The schools of neurofacilitation generally Success in retraining during rehabilitation frown upon attempts to strengthen muscles depends on diverse variables that include the that are hypertonic (see next section). The con- characteristics of a task, changing contexts and cern is that this leads to heightened spasticity environments when performing a task, psy- and diminished motor control. Strengthening chological reinforcements, motivation, atten- exercises, however, may be underutilized by tion, memory for carry-over of what is taught, therapists who are aiming only for compensa- environmental distractions, anxiety, sleep dep- tory gains in function or for more precise mo- rivation, and family support. A variety of experimental stud- for rehabilitating patients with upper motor ies, however, suggest that hemiparetic subjects neuron syndromes. Traditional exercise pro- can increase force output when pushing against grams emphasize repetitive passive and active higher loads, such as when pedaling to gain joint-by-joint exercises and resistance exercises muscular force output, without any worsening in anatomical planes to optimize strength and of motor control. The acquisition of self-care and mo- muscles by pedaling against resistance even at bility skills often takes precedence over the only 20 cycles per minute or by walking on quality of movement, so long as patients are a treadmill also improves cardiovascular fit- safe. Upper and lower extremity orthotics and ness in patients who have at least fair motor assistive devices tend to be used early in ther- control. When needed, therapists also employ NEUROFACILITATION APPROACHES breathing and general conditioning exercises and energy conservation techniques, particu- Many schools have developed what their pro- larly to reduce the energy cost of a pathologi- ponents call neurophysiologic approaches. The approaches involve hands-on in- believes that a task-oriented therapy for am- teraction between the therapist and the pa- bulation is most likely to provide the sensory tient. The interventions utilize sensory stimuli feedback and learning stimuli that can modu- and reflexes to facilitate or inhibit muscle tone late neural assemblies and step generators at and patterns of movement. Therapists may try to activate or suppress a stretch reflex, the This empiric technique, initiated by Kabat and asymmmetric and symmetric tonic neck re- Knott, arose in part from observing smooth, co- flexes, the tonic labyrinthine reflex, and with- ordinated, diagonal and spiral movements in drawal and extensor reflexes. It is based on the belief that since anterior horn cells for synergistic muscles are near each other, an appropriate Neurodevelopmental Techniques level of resistance will bring about changes in Most schools have emphasized a progression in muscle tone by overflow to these motoneurons. Neurodevelop- desired movement and inhibit unwanted mental techniques (NDT) call for reproducing movements. For example, the therapist places the developmental sequence shown by infants the upper extremity in extension, abduction, as they evolve motor control. Specific techniques include repeated abnormal motor behaviors are compensatory, quick stretch, contraction, contraction-relax- and that the quality of motor experiences helps ation, and rhythmic stabilization in which the train subjects for normal movement. Practi- patient tries to hold the arm still as resistance tioners emphasize normal postural alignment is applied by the therapist in an opposite di- prior to any movement. Proprioceptive neuromuscular facilita- ceed in a developmental pattern from rolling tion stretching techniques call for an isometric onto the side with arm and leg flexion on the contraction of the muscle under stretch, such same side, to extension of the neck and legs as the hamstrings, followed by a concentric while prone, to lying prone while supported by contraction of the opposing quadriceps muscle the elbows, and then to static and weight-shift- during stretch of the hamstrings, designated as ing movements while crawling on all four ex- contract-relax agonist-contract (CRAC). These mat activities are followed by sequence is thought to alter the responses of sitting, standing, and, finally, walking. Differ- muscle spindles in a way that increases the ent schools vary in their attempts to activate or maximum range of motion; stimulation may in- mimimize reflexive movements and to train crease in force produced by each muscle as functional movements during ordinary physi- well. Similar One of the potential problems with NDT is spiral and diagonal movement patterns are the delay of standing and walking until the pa- later used for functional activities and walking. These be- liefs, however, are not backed by data from Bobath clinical trials or by information drawn from cur- This NDT approach popularized by the Bo- rent theories regarding motor learning and baths aims to give patients control of abnormal practice-induced skills learning and associated patterns of posture and movement associated neuroplasticity. Abnormal movements provide abnormal sure across joints and allows weight bearing, sensory feedback, which reinforces limited, for example, on the arm through the extended nonselective, abnormal movement. They use pressure or support on key proximal limb or Brunnstrom trunk points to inhibit or facilitate movement. For example, the hemiplegic Specific techniques are recommended for each patient with flexor spasticity of an arm that of the 6 stages of recovery that emerge: (1) flac- rides up during walking is trained to bend for- cidity, (2) limb synergies with onset of spastic- ward in a chair with the arm hanging down. The subject slowly out of synergy, (5) selective over synergistic sits upright with the neck flexed while the arm movement, and (6) near normal control. When stages of recovery have been used as both de- the elbow starts to flex again, the patient re- scriptors and, inappropriately, as outcome peats these steps.
It occurs in those who have pre- including most therapeutic groups order 100 mg desyrel with mastercard anxiety 6th sense, substances of viously been exposed to the drug or a similar substance abuse purchase desyrel 100 mg otc anxiety in dogs symptoms, and over-the-counter preparations. Gastrointestinal effects (anorexia, nausea, vomiting, readministered, the drug reacts with the antibodies constipation, diarrhea) are among the most common to cause cell damage and the release of histamine adverse reactions to drugs. These substances with many drugs from local irritation of the gastroin- produce reactions ranging from mild skin rashes to testinal tract or stimulation of the vomiting center in anaphylactic shock. Diarrhea occurs with drugs that cause local threatening hypersensitivity reaction characterized by irritation or increase peristalsis. It include bleeding or ulceration (most often with aspirin occurs within a few minutes after drug administra- and nonsteroidal anti-inﬂammatory agents) and severe tion and requires emergency treatment with epineph- diarrhea/colitis (most often with antibiotics). Hematologic effects (blood coagulation disorders, occur 1 to 2 weeks after the drug is given. Drug fever is a fever associated with administration leukopenia, agranulocytosis, thrombocytopenia) are of a medication. Drugs can cause fever by several relatively common and potentially life threatening. Hepatotoxicity (hepatitis, liver dysfunction or failure, mechanism is an allergic reaction. Fever may occur biliary tract inﬂammation or obstruction) is potentially alone or with other allergic manifestations (eg, skin life threatening. Because most drugs are metabolized rash, hives, joint and muscle pain, enlarged lymph by the liver, the liver is especially susceptible to drug- glands, eosinophilia) and its pattern may be low induced injury. Drugs that are hepatotoxic include ac- grade and continuous or spiking and intermittent. It etaminophen (Tylenol), isoniazid (INH), methotrexate may begin within hours after the ﬁrst dose if the client (Mexate), phenytoin (Dilantin), and aspirin and other has taken the drug before, or within approximately salicylates. In the presence of drug- or disease-induced 10 days of continued administration if the drug is new liver damage, the metabolism of many drugs is im- to the client. Consequently, drugs metabolized by the liver fever usually subsides within 48 to 72 hours unless 24 SECTION 1 INTRODUCTION TO DRUG THERAPY drug excretion is delayed or significant tissue dam- must have a high index of suspicion so that toxicity can be age has occurred (eg, hepatitis). Many drugs have been implicated as causes of drug fever, including most antimicrobials, several cardiovascular agents (eg, beta blockers, hydralazine, Drug Overdose: General Management methyldopa, procainamide, quinidine), drugs with anti- cholinergic properties (eg, atropine, some antihista- Most poisoned or overdosed clients are treated in emergency mines, phenothiazine antipsychotic agents, and tricyclic rooms and discharged to their homes. Idiosyncrasy refers to an unexpected reaction to a ness and the need for endotracheal intubation and mechani- drug that occurs the ﬁrst time it is given. Serious cardiovascular effects mind-altering drugs, such as opioid analgesics, (eg, cardiac arrest, dysrhythmias, circulatory impairment) are sedative-hypnotic agents, antianxiety agents, and CNS also common and warrant admission to an ICU. Dependence may be physiologic or psy- The main goals of treatment for a poisoned patient are sup- chological. Physiologic dependence produces unpleas- porting and stabilizing vital functions (ie, airway, breathing, ant physical symptoms when the dose is reduced or circulation), preventing further damage from the toxic agent the drug is withdrawn. Psychological dependence by reducing additional absorption or increasing elimination, leads to excessive preoccupation with drugs and drug- and administering speciﬁc antidotes when available and in- seeking behavior. Carcinogenicity is the ability of a substance to cause antidotes are listed in Table 2–2; and speciﬁc aspects of care cancer. Several drugs are carcinogens, including are described in relevant chapters. For patient who are seriously ill on ﬁrst contact, enlist ity apparently results from drug-induced alterations in help for more rapid assessment and treatment. Teratogenicity is the ability of a substance to cause ingestion leads to better patient outcomes. Standard cardiopulmonary Toxic Effects of Drugs resuscitation (CPR) measures may be needed to maintain breathing and circulation. An intravenous (IV) line is Drug toxicity (also called poisoning, overdose, or intoxica- usually needed to administer ﬂuids and drugs, and inva- tion) results from excessive amounts of a drug and may sive treatment or monitoring devices may be inserted. It Endotracheal intubation and mechanical ventilation is a common problem in both adult and pediatric popula- are often required to maintain breathing (in uncon- tions. It may result from a single large dose or prolonged scious patients), correct hypoxemia, and protect the ingestion of smaller doses. Hypoxemia must be corrected quickly to avoid scription, over-the-counter, or illicit drugs. Poisoned pa- brain injury, myocardial ischemia, and cardiac dys- tients may be seen in essentially any setting (e. In some cases, the patient or someone accompanying the Serious cardiovascular manifestations often require patient may know the toxic agent (eg, accidental overdose of pharmacologic treatment.
Talbert desyrel 100 mg amex anxiety symptoms home remedies, sure with elevated pulse desyrel 100 mg sale anxiety zoloft, which indicates volume depletion; and G. New York: always important to evaluate assessment data before giving a McGraw-Hill. Discuss antiplatelet agents in terms of indica- of hemostasis and thrombosis. Discuss characteristics and uses of anticoag- those for analgesic, antipyretic, and anti- ulant, antiplatelet, and thrombolytic agents. Describe thrombolytic agents in terms of indi- in terms of indications for use, onset and cations and contraindications for use, routes duration of action, route of administration, of administration, and major adverse effects. Discuss the use of anticoagulant, antiplatelet, nursing process implications. Describe systemic hemostatic agents for protective measures to prevent abnormal treating overdoses of anticoagulant and bleeding. Critical Thinking Scenario Juan Sanchez, a 56-year-old migrant farmer without health insurance, is admitted to the hospital after an episode of syncope. He is diagnosed with atrial ﬁbrillation and is started on a calcium channel blocker and Coumadin. Reﬂect on: Assessment data that would be helpful to individualize your teaching plan. Discuss the rationale for use of Coumadin for clients with atrial ﬁbrillation. OVERVIEW Atherosclerosis is the basic disease process that often leads to pathologic thrombosis. It begins with accumulation of lipid- Anticoagulant, antiplatelet, and thrombolytic drugs are used filled macrophages (ie, foam cells) on the inner lining of ar- in the prevention and management of thrombotic and throm- teries. Foam cells develop in response to elevated blood lipid boembolic disorders. Thrombosis involves the formation levels and eventually become ﬁbrous plaques (ie, foam cells (thrombogenesis) or presence of a blood clot (thrombus) in covered by smooth muscle cells and connective tissue). Blood clotting is a normal body defense Advanced atherosclerotic lesions also contain hemorrhages, mechanism to prevent blood loss. Eventually, a thrombus may thrombus breaks off and travels to another part of the body, develop at plaque sites and partially or completely occlude it is called an embolus. In coronary arteries, a thrombus may precipi- 832 CHAPTER 57 DRUGS THAT AFFECT BLOOD COAGULATION 833 tate myocardial ischemia (angina or infarction) (see Chap- CLOT LYSIS ter 53); in carotid or cerebral arteries, a thrombus may pre- cipitate a stroke; in peripheral arteries, a thrombus may When a blood clot is being formed, plasminogen (an inactive cause intermittent claudication (pain in the legs with exer- protein found in many body tissues and ﬂuids) is bound to ﬁ- cise) or acute occlusion. Thus, serious impairment of blood brin and becomes a component of the clot. After the outward flow may occur with a large atherosclerotic plaque or a rel- blood ﬂow is stopped and the tear in the blood vessel re- atively small plaque with superimposed vasospasm and paired, plasminogen is activated by plasminogen activator thrombosis. Consequences and clinical manifestations of (produced by endothelial cells or the coagulation cascade) to thrombi and emboli depend primarily on their location and produce plasmin. If the balance between thrombo- genesis and thrombolysis is upset, thrombotic or bleeding dis- THROMBOTIC AND orders result. Thrombotic disorders occur much more often THROMBOEMBOLIC DISORDERS than bleeding disorders and are emphasized in this chapter; bleeding disorders may result from excessive amounts of drugs Thrombosis may occur in both arteries and veins. To aid understanding of drug therapy for thrombosis is usually associated with atherosclerotic plaque, thrombotic disorders, normal hemostasis, endothelial functions hypertension, and turbulent blood ﬂow. These conditions in relation to blood clotting, platelet functions, blood coagula- damage arterial endothelium and activate platelets to initiate tion, and characteristics of arterial and venous thrombosis are the coagulation process. If the obstruction is incomplete or temporary, local tissue ischemia (deﬁcient blood supply) oc- curs. If the obstruction is complete or prolonged, local tissue HEMOSTASIS death or infarction occurs. Venous thrombosis is usually associated with venous sta- Hemostasis is prevention or stoppage of blood loss from an sis. When blood ﬂows slowly, thrombin and other procoagu- injured blood vessel and is the process that maintains the in- lant substances present in the blood become concentrated in tegrity of the vascular compartment. It involves activation of local areas and initiate the clotting process.
9 of 10 - Review by E. Malir
Votes: 196 votes
Total customer reviews: 196