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Potentially purchase isoptin 240 mg without a prescription hypertension 2008, the would only be concerned with whether or not the number of preferences could continue indeﬁnitely lower limit of the conﬁdence interval is greater between the upper solid and broken lines or than the non-inferiority margin (− ) cheap isoptin 240 mg on-line pulse pressure ati. SEQUENTIAL TRIALS In contrast to the open sequential design cheap 40mg isoptin with mastercard hypertension kidney pain, There has been an implicit assumption in the the closed design of Figure 2. Thus this design has a ﬁnite stage and before recruitment commences to the size and a conclusion will always be drawn. This ﬁxed sample size approach Again the solid lines indicate stopping boundaries essentially implies that the data collected during for declaring a statistically signiﬁcant difference the conduct of the trial will only be examined between treatments and if the broken line is for efﬁcacy once the trial has closed to patient crossed, concluding that no signiﬁcant difference accrual. However, the vast majority of Phase III was found between the treatments. Neverthe- to decrease the ﬁnal trial size if the data are less, if one of the factors, say the chemotherapy indicating an advantage to one of the treatments option in the example we discussed previously, and this can be ﬁrmly established at an early stage is stopped by crossing a boundary during the or to extend the trial size in other circumstances. Again, the subsequent 22 TEXTBOOK OF CLINICAL TRIALS 20 A significantly better than B 10 0 No significant difference −10 B significantly better than A −20 0 10 20 30 40 50 Number of preferences Open sequential design. The solid lines indicate stopping boundaries for declaring a statistically significant difference between treatments A and B. If the broken boundary is crossed, then the study stops, concluding that no significant difference was found between the treatments. Potentially the number of preferences could continue indefinitely between the upper solid and broken lines or between the lower solid and broken lines; in such a case no conclusion would ever be reached. Open sequential design patients recruited may then be somewhat dif- terms the use of sequential designs is still some- ferent from those at the ﬁrst stage of the trial. They do not however appear randomised consent design combines aspects of to give an actual clinical example of their use. They were motivated by the difﬁculties range from difﬁculties of ﬁnancing a trial of expressed by clinicians in obtaining consent from uncertain size, making sure the data is fully up- women who they wished to recruit to trials to-date as the trial progresses, to the more tech- with breast cancer. However, Those who were randomised to the standard Whitehead,31 see also Jennison and Turnbull,32 treatment (conventional dressing in Figure 2. On GENERAL ISSUES 23 20 A significantly better than B 10 0 No significant difference −10 B significantly better than A −20 0 10 20 30 40 Number of preferences Closed sequential design. The solid lines indicate stopping boundaries for declaring a statistically significant difference between treatments A and B. For example, if out of ten patients expressing a preference for one or other treatment, nine preferred treatment B and only one preferred A, then the study would stop, concluding that B is significantly better than A. If the broken boundary is crossed, then the study stops and the conclusion is drawn that no significant difference was found between the treatments. Closed sequential design the other hand, those who are randomised to Eligible patients the experimental treatment (MEBO dressing in Figure 2. An alternative is that those randomised to the standard treatment may also Yes No Yes No be asked if they accept that treatment; again, Treat with Treat with Treat with Treat with they are actually given their treatment of choice. Compare the properties of these designs have been 34 Source: After Altman et al. In consent in conjunction with randomisation 24 TEXTBOOK OF CLINICAL TRIALS any event, they have rarely been used in prac- may be of assistance in interpreting the results tice although they continue to be advocated. Despite some technical difﬁculties, it is Nevertheless, in the large antenatal care trial fairly certain that Bayesian methods will become described by Donner et al. RANDOMISATION AND ALLOCATION BAYESIAN METHODS TO TREATMENT the essence of Bayesian methodology in the con- text of the design of clinical trials is to incorpo- We have indicated above that randomisation of rate relevant information into the design process. In fact it is in data monitoring (as trial data accumulate) and the key element. The object of randomisation is to with the ﬁnal analysis and interpretation of the help ensure that the ﬁnal comparison of treatment (now complete) trial data. In theory the informa- options is as unbiased as possible, that is, that any tion available and which is pertinent to the trial in difference or lack of difference observed between question can be summarised into a prior distribu- treatments in efﬁcacy is not due to the method by tion. This may include (hard) information from which patients are chosen for the options under the published literature and/or elicited clinical study.
By applying very high stimulus pulse frequencies discount isoptin 40mg fast delivery blood pressure kidney disease, the auditory neurons can be desynchronized to ﬁre on random sub- harmonics of the stimulation frequencies buy cheap isoptin line blood pressure medication kidney stones, reducing this unnatural synchronization (Rubinstein et al generic 240 mg isoptin visa quitting high blood pressure medication. Unfortunately, such stimulation is less e‰cient in terms of the mean power consumption needed to produce a given level of perceived loudness. This would conﬂict with the emphasis on smaller, lighter prostheses that can be worn on the ear (see Figure 1. Given steady improvements in the power e‰ciency of digital signal processing, the power budget for cochlear implants is increasingly dominated by the power dissipated by pushing stimulation currents through electrodes and cochlear tissues. The combination of more channels and higher stimulus pulse rates would require substantially larger, heavier batteries or more frequent recharge cycles. There are some suggestions that cochlear implant patients and perhaps even normal hearing individuals vary consid- erably in their relative dependence on the wide range of partially redundant acoustic cues that distinguish speech. Conventional cochlear implants are based on replicating the Helmholtzian place-pitch encoding, but some listeners may depend more on decoding of the high-frequency temporal cues that arise from phase-locked transduc- tion of complex acoustic waveforms (Loeb et al. For example, some subjects prefer interleaved patterns of biphasic pulses that avoid electrotonic summation be- tween channels. Other subjects prefer and perform just as well with simultaneous multichannel stimuli consisting of complex analog waveforms obtained by bandpass ﬁltering and compressing the dynamic range of the raw acoustic signal. Despite the wealth of electrophysiological and psychophysical data that can be collected from patients with multichannel cochlear implants, no correlations have yet emerged that account for their often striking di¤erences in performance and pref- erence. Thus, it is not surprising that there are essentially no preoperative predictors to decide which patients should receive which cochlear electrode or which speech- processing system. This forces engineering teams to try to design into the implants a very wide range of signal-processing and stimulus generation and delivery schemes, greatly complicating what is already perhaps the most complex biomedical device ever built. That complexity, in turn, demands a high level of sophistication from the clinicians, who must decide how to program each implant in each patient, and a high level of design for the supporting software that allows those clinicians to navigate and manage all those options. Despite (or perhaps because of) all these emergent complexities and competing strategies, cochlear implants remain the visible proof that sophisticated neural func- tions can be successfully replaced by well-designed neural prosthetic systems. They succeeded clinically and commercially because even the relatively primitive single- channel and multichannel devices that emerged in the late 1970s provided useful ben- eﬁts for the large majority of patients in whom they were implanted (Bilger, 1983). This provided the impetus for much further research and development that vastly improved both the basic performance and general usability of cochlear implants. It also provided a wide range of improved general design and manufacturing tools and techniques that should be applicable to other neural prosthetic devices, provided that we understand their underlying basic science. Visual Prostheses Research on visual prostheses has been going on for even longer than cochlear implant development, but it is still stuck in the category of science ﬁction. Contem- porary hypotheses about visual perception suggested, however, that it would not be possible to create useful, stable percepts from such stimulation. This led to about 10 years of aggressively pursued research to build a practical visual prosthesis based on this approach. It turned out that the surprisingly punctate phosphenes pro- duced by relatively high levels of poorly focused stimulation were the product of the surround-inhibitory neural circuitry of cortical columns, which were discovered about this time. These same circuits, however, also produced uncontrollable nonlinear interactions between adjacent sites of surface stimulation when an attempt was made to combine them into images (reviewed by Girvin, 1988). In the end, this plausible attempt to convert science ﬁction into engineering fact had to be abandoned. In order to overcome the problem of the interaction of stimulus channels, some researchers turned next to developing intracortical microstimulation. Very ﬁne microelectrodes can be inserted about 2 mm into the cortex so that they stimulate just a few neurons within a cortical column, using microamperes of current rather than milliamperes (Ranck, 1975). Given the concurrent advances in the neurophysi- ology of vision, this approach is now primarily an engineering rather than a science problem. Small arrays with a few micro- electrodes have been used successfully to produce stable and apparently combinable phosphenes in patients (Schmidt et al. Scaling this up to hundreds or thousands of separately controlled channels to produce useful (but still crude) images poses daunting problems for fabrication, surgical implantation, bio- compatibility, protective packaging, interconnections, power consumption, psycho- physical ﬁtting and programming, image acquisition, and real-time data processing.
Propranolol (Inderal) IV injection 1–3 mg at a rate of 1 mg/min PO 10–20 mg three or four times per day Class III Potassium Channel Blockers: Treatment of Ventricular Tachycardia and Fibrillation; Conversion of Atrial Fibrillation or Flutter to Sinus Rhythm; Maintenance of Sinus Rhythm (Amiodarone) Amiodarone (Cordarone) Loading dose order isoptin with a mastercard hypertension uncontrolled icd 9, IV buy generic isoptin on-line arteria communicans anterior, 150 mg over 10 min (15 mg/min) buy isoptin 120mg with mastercard heart attack nightcore, then 360 mg over the next 6 h (1 mg/min), then 540 mg over the next 18 h (0. During cardiopulmonary resuscitation, IV 5 mg/kg given by direct injection (undiluted); may be repeated every 15–30 min to a maximum total dose of 30 mg/kg. Ibutilide (Corvert) Weight ≥60 kg: IV infusion over 10 min, 1 mg Weight <60 kg: IV infusion over 10 min, 0. Sotalol (Betapace) PO 80 mg q12h initially, titrated to response; average dose; 160–320 mg daily. Class IV Calcium Channel Blockers: Treatment of Supraventricular Tachycardia Diltiazem (Cardizem) IV injection 0. If ﬁrst dose does not slow the supraventricular tachycardia within 1–2 min, give 12 mg rapidly, and repeat one time, if necessary. Magnesium sulfate IV 1–2 g (2–4 mL of 50% solution), diluted in 10 mL of 5% dextrose solution ECG, electrocardiogram. This group of drugs is declining in clinical use, mainly because of prodysrhythmic effects and resultant in- Class IA drugs have a broad spectrum of antidysrhythmic creased mortality rates. The higher mortality rates occur most effects and are used for both supraventricular and ventricular often in clients with signiﬁcant structural heart disease. Quinidine, the prototype, reduces automatic- 764 SECTION 9 DRUGS AFFECTING THE CARDIOVASCULAR SYSTEM ity, slows conduction, and prolongs the refractory period. It has little effect on atrial tissue and has long been used to maintain NSR in clients with AF or is not useful in treating atrial dysrhythmias. It differs from ﬂutter who have been converted to NSR with digoxin or elec- quinidine in that: trical cardioversion. It does not decrease AV conduction or myocardial con- with long-term quinidine therapy. After in- apeutic serum levels (2 to 6 mcg/mL) are attained within 1 hour travenous (IV) administration of a bolus dose, thera- and persist for 6 to 8 hours. Quinidine is highly bound to peutic effects occur within 1 to 2 minutes and last serum albumin and has a half-life of about 6 hours. This characteristic is advan- tabolized by the liver (about 80%) and excreted in the urine tageous in emergency management but limits lidocaine (about 20%). In alkaline urine (ie, pH >7), renal excretion of use to acute care settings. It is less likely to cause heart block, cardiac asystole, ally contraindicated in clients with severe, uncompensated ventricular dysrhythmias, and heart failure. Lidocaine may be given intramuscularly (IM) in emergen- Quinidine salts used clinically include quinidine gluconate cies when IV administration is impossible. When given IM, (Quinaglute), quinidine sulfate (Quinora), and quinidine poly- therapeutic effects occur in about 15 minutes and last about galacturonate (Cardioquin). Lidocaine is contraindicated in clients allergic active drug (quinidine base) they contain and the rate of ab- to related local anesthetics (eg, procaine). The sulfate salt contains 83% actions may occur in sensitized individuals. They are used to sup- tains 62% active drug, and peak effects occur in 3 to 4 hours. They the polygalacturonate salt contains 60% active drug, and peak are well absorbed from the GI tract, and peak serum levels are effects occur in about 6 hours. The gluconate and polygalacturonate salts re- does not decrease absorption. Oral extended-action preparations of quinidine (Quinidex Phenytoin decreases automaticity and improves conduction Extentabs, Quinaglute Dura-Tabs) also are available. Decreased automaticity helps control Disopyramide is similar to quinidine in pharmacologic dysrhythmias, whereas enhanced conduction may improve actions and may be given orally to adults with ventricular cardiac function. It is well absorbed after oral administra- from digoxin, quinidine, or procainamide, phenytoin may re- tion and reaches peak serum levels (2 to 8 mcg/mL) within lieve dysrhythmias without intensifying heart block. Its only quinidine-like action is excreted by the kidneys and the liver in almost equal pro- is to suppress automaticity; otherwise, it counteracts the ef- portions.
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Herbal medicines discount 120 mg isoptin with amex pulse pressure 88, also called botanicals discount isoptin 40 mg without a prescription blood pressure medication hair loss, phyto- of a client with a particular medical diagnosis should be chemicals buy isoptin pills in toronto blood pressure chart to keep track of readings, and neutraceuticals, are derived from plants; represented. The labels contain essen- Do not take a laxative if you have stomach pain, nau- tial information about the name, ingredients, indications sea, or vomiting, to avoid worsening the problem. Such products can raise blood pres- ✔ Do not take OTC medications longer or in higher doses sure and decrease or cancel the blood pressure–lowering than recommended. This could lead to severe ✔ Note that all OTC medications are not safe for everyone. Many OTC medications warn against use with certain ill- ✔ Store OTC drugs in a cool, dry place, in their original con- nesses (eg, hypertension, thyroid disorders). Consult a tainers; check expiration dates periodically and discard those that have expired. Some speciﬁc precautions include the following: ✔ Measure liquid OTC medications with the measuring de- Avoid alcohol if taking antihistamines, cough or cold vice that comes with the product (some have a dropper or remedies containing dextromethorphan, or sleeping pills. If such a device is not available, use a measur- of them with alcohol may result in excessive, potentially ing spoon. Accurate measurement of sedative-type drug (eg, for nervousness or depression). Older people are more likely to Ask a health care provider before taking other products have adverse drug reactions and interactions because of containing aspirin if you are already taking a regular dose changes in heart, kidneys, and other organs that occur of aspirin to prevent blood clots, heart attack, or stroke. Most testimonials from family members, friends, or celebri- products have not been studied sufficiently to evaluate their ties. With the continued caution that relatively little re- safety or effectiveness; most available information involves liable information is known about these products, self-reports of a few people. Overall, the effects of these several resources are provided in this text, including: products on particular consumers, in combination with other • Table 4–1 describes some commonly used herbal and herbal and dietary supplements, and in combination with dietary supplements. In later chapters, when infor- pharmaceutical drugs, are essentially unknown. Two major concerns are that scientific support for their use are described in more use of supplements may keep the client from seeking treat- detail. For example, in Chapter 7, some products ment from a health care provider when indicated and that the reported to be useful in relieving pain, fever, inﬂam- products may interact with prescription drugs to decrease ther- mation, or migraine, are described. In this chapter, general in- need to have an adequate knowledge base and to incorporate formation is provided (see Client Teaching Guide- their knowledge in all steps of the nursing process (see below). In later chapters, guidelines may em- • Seek information from authoritative, objective sources phasize avoidance or caution in using supplements rather than product labels, advertisements, or personal (text continues on page 59) CHAPTER 4 NURSING PROCESS IN DRUG THERAPY 55 TABLE 4–1 Herbal and Dietary Supplements Name Characteristics Uses Remarks Black cohosh • Thought to relieve menopausal • Most often used to relieve symp- • No apparent advantage over tradi- symptoms by suppressing the re- toms of menopause (eg, ﬂushes, tional estrogen replacement ther- lease of luteinizing hormone (LH) vaginal dryness, irritability) apy (ERT) from the pituitary gland and dysmen- • May also relieve premenstrual syn- • May be useful when ERThis contra- orrhea by relaxing uterine muscle drome (PMS) and dysmenorrhea indicated for a client or the client • Well tolerated; may cause occa- refuses ERT sional stomach upset. In overdose • Recommended dose is 1 tab stan- may cause nausea, vomiting, dardized to contain 20 mg of herbal dizziness, visual disturbances, drug, twice daily and reduced pulse rate • Not recommended for use longer • Most clinical trials done with Reme- than 6 months because long-term femin, in small numbers of women; effects are unknown other trade names include Estroven • Apparently has no effect on and Femtrol endometrium, so progesterone not needed in women with an intact uterus Capsaicin • Derived from cayenne pepper • Capsaicin is a topical analgesic that Applied topically (see Chap. However, tion of use (eg, inhibits platelet more well-controlled studies are aggregation; may depress or stimu- needed before the herb can be late central nervous system [CNS], recommended for these uses. Siberian wort, phenelzine, selegiline, tranyl- ginseng should not be used longer cypromine); headache, mania, and than 3 weeks. These include antidepressants, adrenergics and others Saw palmetto • Action unknown; may have anti- Used mainly to relieve urinary symp- • Reportedly effective in doses of androgenic effects toms in men with benign prostatic 320 mg/day for 1–3 months • Generally well tolerated; adverse hyperplasia (BPH) • Men should have a prostate spe- effects usually minor but may ciﬁc antigen (PSA) test (a blood test include GI upset, headache. Also tive drugs and should not be used • Adverse effects with acute overdose has muscle relaxant effects regularly or chronic use include blurred • Many extract products contain vision, drowsiness, dizziness, ex- 40–60% alcohol and may not be citability, headache, hypersensitivity appropriate for all patients reactions, insomnia, nausea. Also, • Most studies ﬂawed—experts do risk of liver damage from combina- not believe there is sufﬁcient evi- tion products containing valerian dence to support the use of valer- and from overdoses averaging 2. As a result, ✔ When taking herbal or dietary supplements, follow the in- the types and amounts of ingredients may not be stan- structions on the product label. Inappropriate use or tak- dardized or even identified on the product label. In addition, components and active adverse effects or drug–supplement interactions. Some products (eg, echinacea, ents are standardized (meaning that the dose of medicine ephedra, feverfew, garlic, gingko, ginseng, kava, valerian in each tablet or capsule is the same). With or increase risks of bleeding; some have unknown effects herbal medicines especially, different brands of the same when combined with anesthetics, other perioperative med- herb vary in the amounts of active ingredients per rec- ications, and surgical procedures. Dosing is also difficult because a par- ✔ Store herbal and dietary supplements out of the reach of ticular herb may be available in several different dosage children. In this chapter, general infor- drugs (when such information is available).