By C. Amul. Thomas College.
He showed that streptomycin therapy was superior to standard therapy for the treatment of pulmonary tuberculosis buy trihexyphenidyl online now. Finally buy generic trihexyphenidyl on-line, Archie Cochrane was particularly important in the development of the current movement to perform systematic reviews of medical topics buy trihexyphenidyl 2mg. He was a British general practitioner who did a lot of epidemiological work on respira- tory diseases. In the late 1970s, he published an epic work on the evidence for medical therapies in perinatal care. This was the ﬁrst quality-rated systematic review of the literature on a particular topic in medicine. As Santayana said, it is important to learn from history so as not to repeat the mistakes that civilization has made in the past. The improper application of tainted evidence has resulted in poor medicine and increased cost without improving on human suffering. This book will give physicians the tools to evalu- ate the medical literature and pave the way for improved health for all. In the next chapter, we will begin where we left off in our history of medicine and statistics and enter the current era of evidence-based medicine. The most savage controversies are those about matters as to which there is no good evidence either way. Bertrand Russell (1872–1970) Learning objectives In this chapter, you will learn: r why you need to study evidence-based medicine r the elements of evidence-based medicine r how a good clinical question is constructed The importance of evidence In the 1980s, there were several studies looking at the utilization of various surg- eries in the northeastern United States. These studies showed that there were large variations in the amount of care delivered to similar populations. They found variations in rates of prostate surgery and hysterectomy of up to 300% between similar counties. The researchers concluded that physicians were using very different standards to decide which patients required surgery. Both clinicians and policy makers need to know whether the 9 10 Essential Evidence-Based Medicine Fig. Patient values conclusions of a systematic review are valid, and whether recommendations in practice guidelines are sound. This is a paradigm shift that represents both a breakdown of the traditional hierarchical system of medical practice and the acceptance of the scientiﬁc method as the governing force in advancing the ﬁeld of medicine. Evidence-based medicine can be seen as a combination of three skills by which practitioners become aware of, critically analyze, and then apply the best avail- able evidence from the medical research literature for the care of individual patients. This set of skills will help you to develop critical thinking about the content of the medical literature. The application of research results is a blend of the available evidence, the patient’s preferences, the clinical situation, and the practitioner’s clinical experience (Fig. In response to the high variability of medical practice and increasing costs and complexity of medical care, systems were needed to deﬁne the best and, if pos- sible, the cheapest treatments. Individuals trained in both clinical medicine and epidemiology collaborated to develop strategies to assist in the critical appraisal of clinical data from the biomedical journals. In the past, a physician faced with a clinical predicament would turn to an expert physician for the deﬁnitive answer to the problem. This could take the form of an informal discussion on rounds with the senior attending (or consul- tant) physician, or the referral of a patient to a specialist. The answer would come from the more experienced and usually older physician, and would be taken at face value by the younger and more inexperienced physician. That clinical answer was usually based upon the many years of experience of the older physi- cian, but was not necessarily ever empirically tested. Evidence-based medicine has changed the culture of health-care delivery by encouraging the rapid and transparent translation of the latest scientiﬁc knowledge to improve patient care. This new knowledge translation begins at the time of its discovery until its gen- eral acceptance in the care of patients with clinical problems for which that knowledge is valid, relevant, and crucial. Most practitioners have to keep up by regularly reading relevant scientiﬁc journals and need to decide whether to accept what they read. Most health-care workers will spend a greater part of their time functioning as “users” of the medical evidence. They will have the skills to search for the best available evidence in the most efﬁcient way. They will be good at looking for pre- appraised sources of evidence that will help them care for their patients in the most effective way. Finally, there is one last group of health-care workers that can be called the “replicators,” who simply accept the word of experts about the best available evidence for care of their patients. Information Mastery will help you to expedite your searches for information when needed during the patient care process. Ideally, you’d like to ﬁnd and use critical evaluations of clinically important questions done by authors other than those who wrote the study.
For the health-care system discount trihexyphenidyl 2 mg otc, this must also be done at a reasonable cost not only in dollars buy trihexyphenidyl overnight delivery, but also in patient lives 2 mg trihexyphenidyl free shipping, time, and anxiety if an incorrect diagnosis is made. Hypothesis generation in the clinical encounter While performing the H&P, the clinician develops a set of hypotheses about what diseases could be causing the patient’s problem. This list is called the differen- tial diagnosis and some diseases on this list are more likely than others to be present in that patient. When ﬁnished with the H&P, the clinician estimates the probability of each of these diseases and rank-orders this list. The probability of a patient having a particular disease on that list is referred to as the pretest prob- ability of disease. It may be equivalent to the prevalence of that disease in the population of patients with similar results on the medical history and physical examination. The numbers for pretest probability come from one’s knowledge of medicine and from studies of disease prevalence in medical literature. Let’s use the exam- ple of a 50-year-old North American alcoholic with no history of liver disease, who presents to an emergency department with black tarry stools that are sug- gestive of digested blood in the stool. This symptom is most likely caused by esophageal varices, by gastritis, or by a stomach ulcer. The prevalence of each of these diseases in this population is 5% for varices, 55% for ulcer, and 40% for gastritis. In this particular case, the probabilities add up to 100% since there are virtually no other diagnostic possibilities. This is also knows as sigma p equals one, and applies when the diseases on the list of differential diagnoses are all mutually exclusive. Rarely, a person ﬁtting this description will turn out to have gastric cancer, which occurs in less than 1% of patients presenting like this and can be left off the list for the time being. If none of the other diseases are diag- nosed, then one needs to look for this rare disease. In this case, a single diagnostic An overview of decision making in medicine 223 test, the upper gastrointestinal endoscopy, is the test of choice for detecting all four diagnostic possibilities. There are other situations when the presenting history and physical are much more vague. In these cases, it is likely that the total pretest probability can add up to more than 100%. This occurs because of the desire on the part of the physi- cian not to miss an important disease. Therefore, each disease should be con- sidered by itself when determining the probability of its occurrence. This proba- bility takes into account how much the history and physical examination of the patient resemble the diseases on the differential diagnosis. The assigned proba- bility value based on this resemblance is very high, high, moderate, low, or very low. In our desire not to miss an important disease, probabilities that may be much greater than the true prevalence of the disease are often assigned to some diagnoses on the list. Physicians must take the individual patient’s qualities into consideration when assigning pretest probabilities. For example, a patient with chest pain can have coronary artery disease, gastroesophageal reﬂux disease, panic disorder, or a combination of the three. In general, panic disorder is much more likely in a 20- year-old, while coronary artery disease is more likely in a 50-year-old. When con- sidering this aspect of pretest probabilities, it becomes evident that a more real- istic way of assigning probabilities is to have them reﬂect the likelihood of that disease in a single patient rather than the prevalence in a population. This allows the clinician to consider the unique aspects of a patient’s history and physical examination when making the differential diagnosis. Constructing the differential diagnosis The differential diagnosis begins with diseases that are very likely and for which the patient has many of the classical symptoms and signs. Next, diseases that are pos- sible are included on the list if they are serious and potentially life- or limb- threatening. These are the active alternatives to the working diagnoses and must be ruled out of the list. This means that the clinicians must be relatively certain from the history and physical examination that these alternative diagnoses are not present. Put another way, the pretest probability of those alternative diseases is so vanishingly small that it becomes clinically insigniﬁcant. If the history and physical examination do not rule out a diagnosis, then a diagnostic test that can reliably rule it out must be performed. Diseases that can be easily treated can also be included in the differential diagnosis and occasionally, the diagnosis is con- ﬁrmed by a trial of therapy, which if successful, conﬁrms the diagnosis. Last to be included are diseases that are very unlikely and not serious, or are more difﬁcult and potentially dangerous to treat. These diseases are less possible because they 224 Essential Evidence-Based Medicine Fig.
Healthy buy trihexyphenidyl 2mg on-line, sick and dead birds are often found together during an outbreak with carcases in various stages of decay order genuine trihexyphenidyl on line. Affected birds may be unable to use their wings and legs normally or unable to control the third eyelid (may not be visible) 2mg trihexyphenidyl free shipping, neck muscles and other muscles and may therefore be seen propelling themselves using weak wings across water and mudflats. Birds with paralysed neck and leg muscles cannot hold their heads up and may therefore drown. Death is frequently caused by respiratory failure caused by the toxin paralysing muscles used for breathing. Affected cattle and horses tend to have a stiff gait and are often found recumbent with laboured breathing. In humans, symptoms include blurred vision, dry mouth, difficulty in swallowing or speaking, general weakness, and shortness of breath. The illness may progress to complete paralysis and respiratory failure, but, if treated, rarely death. The disease often affects the same wetlands, and the same spots within a wetland, each year. Recommended action if Contact and seek assistance from animal and human health professionals suspected immediately if there is any illness in birds and/or people. Diagnosis Avian botulism can be tentatively diagnosed by the clinical signs and the exclusion of other neurological diseases. Detection of the toxin by health professionals is needed for a definitive diagnosis. Diagnosis in animals relies on identifying the toxin in faeces, blood, vomit, gastric aspirates, respiratory secretions or food samples. Serum is required for diagnosis in sick birds and tissue samples such as clotted heart blood, stomach contents, or liver are required for diagnosis in dead birds. In wild birds clinical diagnosis is most frequently made - flaccid paralysis being very characteristic. Some actions can be taken to mitigate environmental conditions that increase the likelihood of outbreaks. Inputs will introduce large amounts of decaying matter and may cause death of aquatic life (which forms a nutrient source for the bacteria). In areas managed primarily for migratory waterbirds, avoid flooding land that has been dry for a long time and avoid lowering water levels when warm. Both could result in die-offs of fish and aquatic invertebrates whose carcases could then become substrates for bacterial growth. In areas managed for shorebirds, lowering water levels provides essential habitat. Waterfowl can be redistributed to lower risk areas by draining contaminated areas whilst creating/enhancing other habitats. Take care to ensure these measures do not cause the dispersal of infected birds out of the area. Quick and careful collection of carcases and their disposal by burial or burning, especially during outbreaks, removes nutrient sources for bacteria. Take care to avoid contaminating new areas whilst carcases are being transported to the laboratory and disposal site. Wear gloves and thoroughly wash exposed skin surfaces after any contact with contaminated birds. Avoid locating power lines across marshes used by large concentrations of waterbirds. Sick waterfowl are easily caught and can recover if provided with freshwater and shade, or injected with antitoxin. Monitoring and surveillance Regular monitoring of live and dead birds, particularly in endemic areas and areas where migratory birds are concentrated, and during warm periods, can help identify early stages of an outbreak and allows disease control activities to be activated before any outbreaks develop further. Document environmental conditions, outbreak sites and dates of outbreak occurrence and cessation. Where possible, monitor and modify environmental conditions to prevent the pH and salinity of wetlands from reaching or being maintained within high hazard levels. Providing nutritional supplements of protein and phosphorus to reduce bone chewing among cattle. Take care with the harvesting and storage of feeds to reduce the possibility of small animals contaminating feeds. Wildlife ►Section above: Prevention and control in wetlands – overall ►Case study 3-2. Humans Thoroughly cook fish or waterfowl to an internal temperature of at least 180°F to destroy the toxin. Anglers and hunters should never harvest fish or waterfowl that appear sick or dying in areas where avian botulism is known to be present.
It can be life saving for the baby but has the potential to cause chronic joint pain in the mother and risk of infection buy trihexyphenidyl 2 mg otc. If you have an obstructed labour or mal-positioned baby buy 2 mg trihexyphenidyl otc, and/or the baby is dead 2mg trihexyphenidyl with amex, and there are no facilities to perform a caesarean section then as unpalatable as it sounds, delivering the baby in pieces may be the only option to save the mother. If the labour is prolonged with the head deeply embedded in the pelvis, pressure injuries can occur in the mother’s pelvic floor, causing a fistula between the vagina and the bladder or bowel to occur – these are very common in third world countries and very disabling. This is extremely unpleasant but can be done with a sterile wire saw and scissors. This is rarely required and is a last ditched solution to save the mother, as in a major disaster situation with no conceivable access to health care. If not done in a sterile manner infection will be introduced and will likely prove fatal to the mother “A Book for Midwives” by Susan Kline, Hesperian Foundation 1995 is the best single source of info on delivery, problems, and newborn care in an austere environment. If it is something you feel uncomfortable with then please skip to the next section. Unfortunately abortion has been a fact of life for centuries and merits discussion. Prior to legal abortion in the 1970s emergency departments on a daily basis saw young women with septic abortion and even tetanus from illegal abortion. Historically a wide range of plants have been used to induce abortion on most continents and in most cultures. They have varying efficacy but most do work to a - 115 - Survival and Austere Medicine: An Introduction degree. If this is interest to you most reputable herbal medicine texts cover this topic in varying detail. In the first trimester, psychological issues aside, surgical abortion is a very safe relatively minor procedure with a low complication rate. Infection and perforation of the uterus are potentially life threatening and were very common in backstreet abortion. One point of view is that in an austere situation with limited access to medical care a first trimester termination, provided it is done in a sterile manner with appropriate instruments is safer than carrying the pregnancy to term. This is not the case, however, with second and third trimester terminations which if performed in an austere situation are likely to prove fatal to the mother. Breasting feeding is the Gold standard by a considerable distance for nutrition for children in the first 6 months of life. It is also the ideal survival food requiring no space or rotation and is readily portable. The most reliable method of ensuring the baby is getting sufficient milk is their general contentment and steady weight gain. While there are many causes for irritable babies, when combined with poor weight gain it suggests inadequate nutrition. A common cause is insufficient breast milk although other nutritional problems can present in a similar fashion. In the event that the mother’s milk supply is insufficient or falling off there are several options. This was very common practice until the advent of commercial infant formula in the last century. If the mother had insufficient milk for the baby then another lactating woman fed the baby. There were women who did this as a career, and in upper class England this was common so the aristocratic woman could “preserve” her figure. In an austere situation this is only an option if there is another breast-feeding mother in your group either with enough spare milk or an older child who can be weened. Nipple stimulation to simulate sucking 3-4 times per day can lead to the onset of milk production after 7-10 days. This is more likely to be successful and to occur earlier in women who have previous had children and had breast-fed for longer periods. This is usually done using a manual or electric pump, however, it is possible to milk the human breasts in a similar fashion to milking cows! It can be given to the baby via a bottle and teat or from a cup – even newborn babies are able to sip from a cup although this may take a little practice. The baby sucks on your finger and sucks milk up the tube – commonly used sizes are 6 or 8 French. If you have infants or plan on having children it is important that you give some consideration to what you would do if you were unable to breast feed the infant. The unfortunate fact is that storing and rotating 6 months worth of infant formula may be prohibitively expensive for most and this is a risk you may need to live with. In a truly austere situation it is possible to make infant formula from stored food although this is clearly sub-optimal. The following table contains several recipes for using stored food components to manufacture baby formula – please accept the caution that this is only for a life-threatening situation where there are no alternatives and the baby will otherwise die.