By T. Einar. Marlboro College. 2018.
For example cheap 5mg finast with amex, quaternary ammonium salts purchase finast 5mg without prescription, which are permanently charged order 5mg finast free shipping, can be used as an alternative to an amine in a structure in order to restrict the passage of a drug across a membrane buy 5mg finast overnight delivery. The structure of the anticholinesterase neostigmine, developed from physostig- mine, contains a quaternary ammonium group, which stops the molecule from crossing the blood–brain barrier (Appendix 11). However, modern techniques such as computer modelling (Chapter 5) and combinatorial chemistry (Chapter 6) introduced in the 1970s and 1990s respectively are likely to reduce the number of intuitive discoveries. Computer modelling has reduced the need to synthesize every analogue of a lead compound. It is also often used retrospectively to confirm the information derived from other sources. Combinatorial chemistry, which originated in the field of peptide chemistry, has now been expanded to cover other areas. The term covers a group of related techniques for the simultaneous production of large numbers of compounds for biological testing. Consequently, it is used for structure action studies and to discover new lead compounds. It originally started with drugs and lead compounds derived from natural sources, such as animals, plants, trees and microorganisms. Today, natural sources are still important, but the majority of lead compounds are synthesized in the laboratory. The nature of these synthetic compounds is initially decided from a consideration of the biochemistry of the pathogenic condition. Today, many discoveries start with biological testing (bioassays or screening programme) by pharmacologists of the potential sources in order to determine the nature of their pharmacological activity as well as their potencies. In random screening pro- grams all the substances and compounds available are tested regardless of their structures. The random screening of soil samples, for example, led to the discovery of the streptomycin and tetracycline antibiotics as well as many other lead compounds. Random screening is still employed, but the use of more focused screening procedures where specific structural types are tested is now more common. Once a screening programme has identified substances of pharmacological activity of interest, the compound responsible for this activity is isolated and used as a lead compound for the production of related analogues. Analogues are made of the most promising of these compounds and they in turn are subjected to the screening procedure. This sequence of selective screening and synthesis of analogues may be repeated many times before a potentially useful drug is found. Often the sequence has to be abandoned as being either unproductive or too expensive. However, the large diversity of potential natural sources in the world makes the technique of random screening a rather hit or miss process. The screening of local folk remedies (ethnopharmacology) offers the basis of a more systematic approach. Once screening identifies a material containing an active compound, the problem becomes one of extraction, purification and assessment of the pharma- cological activity. However, the isolation of useful quantities of a drug from its land or sea sources can cause ecological problems. However, the production of large quantities of Taxol from this source would result in the wholesale distruction of the tree, a state of affairs that is ecologically unacceptable. These compounds are synthesized so that their pharmacological action may be evaluated. Once a suitably active lead is found, structural analogues of that lead are produced and screened in the hope that this procedure will eventually produce a compound that is suitable for clinical use. Obviously this approach is labour intensive and a successful out- come depends a great deal on luck. Various modifications to this approach have been introduced to reduce this element of luck (see Chapters 4–6).
There are no guides for theory (as described in Chapter 1) before moving theory analysis and evaluation that are adequate to theory analysis and evaluation order finast 5 mg overnight delivery. These have tions is adequate for study of any nursing theory discount finast 5mg visa, continued in use over time and offer direction for choose the definition that seems to best fit with guides in use today generic 5mg finast free shipping. For ex- ory should: ample cheap 5mg finast fast delivery, one of the definitions by Chinn and Jacobs (1987) or Chinn and Kramer (2004) may be chosen • define the congruence of nursing practice with for using theory in research. The definition by Silva societal expectations of nursing decisions and (1997) may be more appropriate for study of nurs- actions; ing theory for use in practice. Another way to think • clarify the social significance of nursing, or the about this is to consider whether the definition of impact of nursing on persons receiving nursing; nursing theory in use fits the theory being analyzed and and evaluated. Look carefully at the theory, read the • describe social utility, or usefulness of the theory theory as presented by the theorist, and read what in practice, research, and education. The whole The following are outlines of the most fre- quently used guides for analysis and evaluation. Parts about nursing theory of the individual nursing of the theory without the whole will not scholar and offer various interesting approaches to be fully meaningful and may lead to mis- the study of nursing theory. The guidelines set forth questions that tion of these elements may take place, as summa- clarify the facts about aspects of theory: purpose, rized here: concepts, definitions, relationships, structure, as- sumptions, and scope. These authors suggest that • Relations between structure and function of the the next step in the evaluation process is critical re- theory, including clarity, consistency, and sim- flection about whether and how the nursing theory plicity works. Questions are posed to guide this reflection: • Diagram of theory to further understand the theory by creating a visual representation • Is the theory clearly stated? Questions for analysis in this frame- work flow from the structural hierarchy of nursing knowledge proposed by Fawcett and defined in Chapter 1. The questions for evaluation guide ex- amination of theory content and use for practical Nursing theory, knowledge development purposes. Following is a summary of the Fawcett through research, and nursing practice are (2000) framework. In order to en- For theory analysis, consideration is given to: hance both nursing practice and nursing the- ory, it is incumbent upon the practicing nurse • scope of the theory to study theory, just as it is upon the theorist • metaparadigm concepts and propositions in- to study the practice of nursing. Considering cluded in the theory a commitment to study nursing theory raises • values and beliefs reflected in the theory many questions from nurses about to un- • relation of the theory to a conceptual model and dertake this important work. This chapter to related disciplines presented some of the questions worth con- • concepts and propositions of the theory sidering before undertaking extensive study For theory evaluation, consideration is given to: and deciding on a theory to guide practice. Analysis and evaluation of nursing theory • significance of the theory and relations with are the main ways of studying nursing structure of knowledge theory. Literature presents a number of dif- • consistency and clarity of concepts, expressed in ferent guides to analyzing and evaluating congruent, concise language theory. Aesthetic Meleis (1997) states that the structural and knowing grounded in an explicit conception of nursing. Fundamental patterns of knowing in nurs- are assumptions, concepts, and propositions of the ing. Integrated knowledge de- nurse-client interactions, environment, and nurs- velopment in nursing (6th ed. The structure of nursing knowledge: Analysis care through self-awareness and reflection (pp. Parker Study of Theory for Nursing Practice A Guide for Study of Nursing Theory for Use in Practice Study of Theory for Nursing Administration Summary References Nurses, individually and in groups, are affected Theories and practices from related disciplines by rapid and dramatic change throughout health are brought to nursing to use for nursing purposes. Nurses practice in increas- The scope of nursing practice is continually being ingly diverse settings and often develop organized nursing practices through which accessible health The scope of nursing practice is continu- care to communities can be provided. Community ally being expanded to include additional members may be active participants in selecting, knowledge and skills from related designing, and evaluating the nursing they receive. This guide was tice in hospitals, an increasing number of nurses developed for use by practicing nurses and students practice elsewhere in the community, taking the in undergraduate and graduate nursing education venue of their practice closer to those served by programs. The guide may be used to to provide nursing often realize that they share the study most of the nursing theories developed at all same values and beliefs about nursing.
An isolated spinous process fracture typically occurs in the setting of trauma and is considered a stable vertebral fracture buy finast 5 mg without a prescription. This patient presents with (vertigo) and (atypical arm pain with exercise) buy generic finast 5 mg, symptoms consistent with This phenomenon occurs in patients with subclavian artery occlusion or steno- sis proximal to the vertebral artery branch buy finast 5mg free shipping, which causes retrograde blood flow in the vertebral artery with ipsilateral arm exercise purchase finast 5 mg on-line. Collateral arteries arising from the subclavian artery distal to the obstruction deliver blood to the arm. During arm exercise these vessels dilate and siphon blood from the head, neck, and shoulder to increase perfusion of ischemic arm muscles. This results in temporary reversal of blood flow in the vertebral artery leading to vertebrobasilar insufficiency and symptoms of vertigo, dizziness, syn- cope, dysarthria, and diplopia. Uterine rupture Cocaine (b) (c) painless (d)painless (e) Placenta previa vaginal bleeding not painful. Ammonia is present in many household cleaners, as a cooling agent in refrigerator units, and as a fertilizer owing to its high nitrogen content and may act differently depending in what form it is in. For example, it may freeze skin on contact or affect breathing because of its vapors. Formic acid is a caustic organic acid used in many industries that causes a coagulation necrosis. Treatment for exposure to all of these chemicals includes copious irrigation and observation for systemic side effects. The reported incidence of infection from these bites may be as high as 30% to 50%, with many patients presenting only after an infection has incurred. It is important to note that cat bites have a higher infection rate compared to dog bites, given the typical puncture wound that inoculates bacteria down the track deep into tissue and becomes enclosed. Patients need to be followed closely as these infections may seed deep into joints and tissue requiring debridement. Antibiotic topicals, such as bacitracin, would be inappropriate given the high virulence of this organism. In the adult, each anterior or posterior sur- face of the upper extremity and head are equal to 4. More percentage is dedicated to the head given their larger head-to-body ratios (7% in children and 9% in infants). The Prophylactic antibiotics are not warranted in these cases, given the chance of increased future resistance rates. For areas of greater involvement and inhalation burns, fluid resuscitation may patients with a history of altitude illness as prophylaxis. It works to decrease the formation of bicarbonate by inhibiting carbonic anhydrase. It also decreases bicarbonate absorption in the kidney, causing a metabolic acidosis, which stimulates hyperventilation. This compensatory mechanism is turned off when the pH is close to the physiologic range of 7. It’s this hyperventilation that counters the altitude-induced hypoxemia, thereby relieving symptoms. Dexamethasone works to decrease vasogenic edema and decrease intracranial pressure. Nifedipine works by decreasing pulmonary artery pres- sure in high-altitude pulmonary edema as does the diuresis resulting from furosemide. Morphine is thought to reduce pulmonary blood flow and decrease hydrostatic forces in pulmonary edema. These injuries may inflict fractures, cardiovascular collapse, burns, blunt abdominal injuries, and neurologic damage. Although 50 to 300 people die because of lightning strikes each year in the United States, most injuries sustained are not lethal. Ninety-five percent of clinical cases result from the species, another member of the which was imported from Brazil in the 1930s. This ant is found in many of the southern states given that it cannot survive long winters and is slowly replacing the less dangerous species native to North America.
Khat Khat consists of the young leaves of the Catha edulis plant; it is usually chewed for its stimulant effect when fresh but may be drunk as an infusion of leaves discount finast 5mg otc. In the United Kingdom purchase finast 5mg, it is sold legally (it is illegal in the United States) and is used by Somali populations (72 finast 5 mg sale,73) proven finast 5mg. The main component is cathinone, with effects similar to those of amphetamine, resulting in euphoria, Substance Misuse 301 increased alertness, and anorexia (74). Heavy khat consumption may result in mania-like symptoms, paranoia, and an acute schizophrenia-like psychosis, usually resolving within weeks of cessation of use (76,77). Although there is no specific physical withdrawal syndrome, depression, hypersomnia, and loss of energy may occur when khat use is stopped (75). Marijuana Marijuana is the most commonly used illicit drug in the United Kingdom (with 11% of 16–59 years olds having used it in the last year; see ref. There are several forms, including hashish (a resin), herbal cannabis (a green-colored preparation made from the leaves of the plant), and cannabis oil. The onset of effects is reported as being more rapid, and the hallucinogenic properties are heightened. Tolerance develops to many effects of cannabis, including the “high” with chronic use, and an abstinence syndrome has been described with dis- turbed sleep, decreased appetite, restlessness, irritability, and sweating. With- drawal symptoms are usually mild and short-lived, although they may be more severe in heavy regular users (82). Anabolic Steroids Anabolic steroids may be taken orally or intramuscularly by body builders or other individuals who want to enhance their physical appearance. Research has shown that injections of testosterone enanthate increase muscle size and strength, especially when combined with exercise (83). To achieve the desired effect, different steroids are taken in cycles, with rest periods in between, a regime known as “stacking,” or, alternatively, increasing doses of the same ste- roid are taken, a so-called drug pyramid (84). Most of the steroids sold in the United Kingdom are counterfeit rather than produced by legitimate pharmaceu- tical companies. Consequently, they may contain a different steroid from the 302 Stark and Norfolk 302 Substance Misuse 303 one indicated on the bottle, and scant reliance can be placed on the reported dose because they may have little or no steroid in them at all (85). General effects of anabolic steroids (86) include baldness, acne (typi- cally affecting the shoulders and upper back), raised blood pressure and heart rate, fluid retention, and a reduction in high-density lipoprotein cholesterol. Gynecomastia may occur, and the prostate gland may swell, resulting in impaired micturition. Most of these effects are dose dependent and more likely with prolonged administration. While the drug is being taken, there is a significant reduction in testoster- one production by the testes so that sperm output and quality are decreased, and a return to normal can take many months after drug use is stopped. The effect on sex drive is variable, but overall it seems that the sex drive increases at the beginning of a steroid-using cycle, and then decreases to below normal after several weeks of use. Drive may remain below normal levels even after the drug is stopped, until such time as the testes start producing testosterone again. In women, menstrual irregularities are reported, with permanent enlarge- ment of the clitoris. There may also be growth of facial and body hair, male pattern baldness, and decreased breast size. Abuse of sex steroids by recre- ational body builders may be an unrecognized cause of subfertility (88). Liver function tests may show abnormalities that usually return to nor- mal once the drug is stopped. Drug-induced jaundice can be caused by tempo- rarily impaired excretory function, and peliosis hepatitis, in which the liver tissue is replaced by blood-filled cysts, may occur, as can liver tumors (89) and Wilms’ tumor. Initial use may result in stimulatory effects, such as increased confidence, decreased fatigue, heightened motivation, agitation, irritability, and insom- nia, which may progress to argumentative and aggressive behavior and major mood disturbances including depression, mania, and hypomania (90,91).
Blood from the liver soon reaches pulmonary vessels so that surviving gut bacteria readily cause pulmonary infection; increased capillary permeability enables pulmonary oedema formation finast 5 mg otc, and possible shunting trusted finast 5mg. As suction raises intracranial pressure order 5 mg finast free shipping, patients should be preoxygenated and duration and number of passes should be minimised (see Chapter 22) 5mg finast sale. Suction may also cause trauma, so that catheters withdrawn should be observed for blood (type, amount) as well as sputum (type, colour, amount). Hepatopulmonary syndrome occurs in up to 30 per cent of patients with endstage failure (Isaac & Manji 1997). Pathology is unclear; there is no specific treatment and resolution can be spontaneous, but mortality remains high. Hepatopulmonary syndrome is an indication for liver transplantation (Isaac & Manji 1997. Cardiovascular compromise is caused by ■ hypovolaemia ■ vasodilation ■ increased capillary permeability ■ reduced cardiac return. As prolonged hypotension predisposes to multiorgan dysfunction, nurses should closely assess and monitor cardiovascular function. Inotropes will probably be needed, although may have little effect if sympathetic pathways are damaged. Stress responses (see Chapter 3) increase blood and intracranial pressure, and so patients should be nursed in quiet environments with minimal sensory stimulation. There is no detectable histological change to renal tissue, and kidneys resume normal function following hepatic transplantation (Hinds & Watson 1996); without transplantation, mortality exceeds 90 per cent (Hinds & Watson 1996). Unlike acute tubular necrosis, relatively normal sodium reabsorption and urine concentration is maintained during hepatorenal syndrome. The liver has more than 500 metabolic functions, and so hepatic failure causes complex disorders. Electrolyte disorders from hepatic hypofunction are often compounded by renal and capillary epithelial changes. Reduced free water clearance can dilute electrolyte concentrations, causing hyponatraemia and hypokalaemia (Sussman 1996). Prolonged malnourishment (especially with alcoholism), vomiting and nasogastric drainage may compound hypokalaemia, while dehydration (e. Electrolyte imbalances have varied systemic effects, including dysrhythmias from hypokalaemia and oedema formation from hyponatraemia. Hepatic failure 381 Metabolic acidosis may occur from ■ hypoperfusion (anaerobic metabolism) ■ renal impairment ■ gastric acid loss (vomiting, aspiration) (Adam & Osborne 1997) Impaired toxin metabolism and clearance increases sensitivity to, and effects of, many drugs and metabolites. With chronic failure, hepatocellular necrosis prevents glycogenolysis, which causes potential hypoglycaemia (Lockhart-Wood 1996), necessitating frequent blood sugar monitoring and probably glucose supplements. Artificial livers The development of artificial livers has been slow and problematic, but shortage of donor livers prompted experiments with xenoperfusion. Cadaver and baboon livers have achieved extracorporeal support for up to 75 days (Conlin 1995), although immunologie intolerance makes xenoperfusion impractical (Sussman 1996). Temporary support is possible from hepatocytes grafted onto semipermeable hollow-fibre devices (visually similar to those used for haemofiltration), which provide support until transplantation (Fristoe et al. Nurses should encourage families to express their needs Intensive care nursing 382 and emotions, but it may be necessary to involve counselling or other services. Liver function affects many other organs and systems, and so the care of patients with liver dysfunction requires a range of knowledge and skills. Intracranial hypertension, a major complication of hepatic failure, is discussed further in Chapter 22. Further reading Hawker is a leading authority on hepatic failure; her chapter (1997a) is an accessible and useful source. Langley and Pain (1994) discuss some of the options for medical treatment, while Stanley et al. Artnal and Wilkinson (1998) give a case study of fulminant failure from paracetamol. Clinical scenario Fabio Galvani is a 26-year-old male who has recently completed a six-month backpacking trip to southeast Asia. Since his return he has been feeling increasingly unwell with nausea, vomiting, fever with influenza-like symptoms.