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41-404: The differential diagnosis of wheezing is wide, and the reason for wheezing in a given patient is determined by considering the characteristics of the wheezes and the historical and clinical findings made by the examining physician. The term "wheeze" is also used as a clinical condition describing wheezing in preschool children, termed as "preschool wheeze". Wheezes occupy different portions of

82-460: A die has landed the outcome is certain by 100%, but the probability that it Would Have Occurred in the First Place (hereafter abbreviated WHOIFP ) is still 1/6. In the same way, the probability that a presentation or condition would have occurred in the first place in an individual (WHOIFPI) is not same as the probability that the presentation or condition has occurred in the individual, because

123-433: A differential diagnosis by epidemiology aims to estimate the probability of each candidate condition by comparing their probabilities to have occurred in the first place in the individual. It is based on probabilities related both to the presentation (such as pain) and probabilities of the various candidate conditions (such as diseases). The statistical basis for differential diagnosis is Bayes' theorem . As an analogy, when

164-422: A differential diagnosis in the evaluation of a cough, even if the final diagnosis is common cold ). More generally, a differential diagnostic procedure is a systematic diagnostic method used to identify the presence of a disease entity where multiple alternatives are possible. This method may employ algorithms, akin to the process of elimination , or at least a process of obtaining information that decreases

205-437: A differential diagnosis of borderline personality disorder , given the similarity in the symptoms of both conditions. Strategies used in preparing a differential diagnosis list vary with the experience of the healthcare provider. While novice providers may work systemically to assess all possible explanations for a patient's concerns, those with more experience often draw on clinical experience and pattern recognition to protect

246-499: A differential diagnostic procedure can be used concomitantly or alternately with protocols, guidelines, or other diagnostic procedures (such as pattern recognition or using medical algorithms ). For example, in case of medical emergency , there may not be enough time to do any detailed calculations or estimations of different probabilities, in which case the ABC protocol (airway, breathing and circulation) may be more appropriate. Later, when

287-578: A good prognosis and only supportive treatment is required. Meanwhile, multi-trigger wheezing is associated with allergy and a family history of asthma. Symptoms occur in between wheezing episodes and are likely to persist beyond early childhood. Due to difficulty in differentiating both types of wheeze, the diagnosis of viral-induced versus multi-trigger wheeze may be delayed for a period of time until its clinical course has become clear. To wheeze implies an inability to speak clearly, so in politics it refers to an unorthodox or less than ethical maneuver that

328-404: A system beyond the original design. In implementing a workaround it is important to flag the change so as to later implement a proper solution. Placing pressure on a workaround may result in later system failures. For example, in computer programming workarounds are often used to address a problem or anti-pattern in a library , such as an incorrect return value . When the library is changed,

369-402: Is a bypass of a recognized problem or limitation in a system or policy. A workaround is typically a temporary fix that implies that a genuine solution to the problem is needed. But workarounds are frequently as creative as true solutions, involving outside the box thinking in their creation. Typically they are considered brittle in that they will not respond well to further pressure from

410-439: Is a method of analysis that distinguishes a particular disease or condition from others that present with similar clinical features. Differential diagnostic procedures are used by clinicians to diagnose the specific disease in a patient , or, at least, to consider any imminently life-threatening conditions. Often, each individual option of a possible disease is called a differential diagnosis (e.g., acute bronchitis could be

451-644: Is absent). A diagnostician can be selective, considering first those disorders that are more likely (a probabilistic approach), more serious if left undiagnosed and untreated (a prognostic approach), or more responsive to treatment if offered (a pragmatic approach). Since the subjective probability of the presence of a condition is never exactly 100% or 0%, the differential diagnostic procedure may aim at specifying these various probabilities to form indications for further action. The following are two methods of differential diagnosis, being based on epidemiology and likelihood ratios, respectively. One method of performing

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492-414: Is approximately equal to that of a population that is as similar to the individual as possible except for the current presentation, compensated where possible by relative risks given by known risk factor that distinguish the individual from the population: where: The following table demonstrates how these relations can be made for a series of candidate conditions: One additional "candidate condition"

533-544: Is continued in the example of the method described in the next section. The procedure of differential diagnosis can become extremely complex when fully taking additional tests and treatments into consideration. One method that is somewhat a tradeoff between being clinically perfect and being relatively simple to calculate is one that uses likelihood ratios to derive subsequent post-test likelihoods. The initial likelihoods for each candidate condition can be estimated by various methods, such as: Workaround A workaround

574-412: Is not actually illegal, but relies on an element of deception or sleight of hand, being an intermediate between a workaround and a scam In this context wheezing is notably linked with the slang expression Joe Blow meaning any external person or group beyond a secretive fraternity (See also insider trading ) Differential diagnosis In healthcare, a differential diagnosis ( DDx )

615-438: Is the instance of there being no abnormality, and the presentation is only a (usually relatively unlikely) appearance of a basically normal state. Its probability in the population ( P(No abnormality in population) ) is complementary to the sum of probabilities of "abnormal" candidate conditions. This example case demonstrates how this method is applied but does not represent a guideline for handling similar real-world cases. Also,

656-599: The respiratory cycle depending on the site of airway obstruction and its nature. The fraction of the respiratory cycle during which a wheeze is produced roughly corresponds to the degree of airway obstruction. Bronchiolar disease usually causes wheezing that occurs in the expiratory phase of respiration. As a rule, extrathoracic airway obstruction produce inspiratory sounds. Intrathoracic major airway obstruction produces inspiratory as well as expiratory sounds. Distal airway obstruction predominantly produces expiratory sounds. The presence of expiratory phase wheezing signifies that

697-441: The standard reference range , which, by most definitions, classifies as hypercalcemia , which becomes the "presentation" in this case. A clinician (who becomes the "diagnostician" in this example), who does not currently see the patient, gets to know about his finding. By practical reasons, the clinician considers that there is enough test indication to have a look at the patient's medical records . For simplicity, let's say that

738-412: The "probabilities" of candidate conditions to negligible levels, by using evidence such as symptoms, patient history, and medical knowledge to adjust epistemic confidences in the mind of the diagnostician (or, for computerized or computer-assisted diagnosis, the software of the system). Differential diagnosis can be regarded as implementing aspects of the hypothetico-deductive method , in the sense that

779-424: The currently available information becomes: Primary hyperparathyroidism can be assumed to cause hypercalcemia essentially 100% of the time (r PH → hypercalcemia = 1), so this independently calculated probability of primary hyperparathyroidism (PH) can be assumed to be the same as the probability of being a cause of the presentation: For cancer , the same time-at-risk is assumed for simplicity, and let's say that

820-439: The end of both expiratory and inspiratory phases usually signify the periodic opening of deflated alveoli , as occurs in some diseases that lead to collapse of parts of the lungs . The location of the wheeze can also be an important clue to the diagnosis. Diffuse processes that affect most parts of the lungs are more likely to produce wheezing that may be heard throughout the chest via a stethoscope. Localized processes, such as

861-402: The example uses relatively specified numbers with sometimes several decimals , while in reality, there are often simply rough estimations, such as of likelihoods being very high , high , low or very low , but still using the general principles of the method. For an individual (who becomes the "patient" in this example), a blood test of, for example, serum calcium shows a result above

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902-427: The finding of hypercalcemia. The main causes of hypercalcemia are primary hyperparathyroidism (PH) and cancer , so for simplicity, the list of candidate conditions that the clinician could think of can be given as: The probability that 'primary hyperparathyroidism' (PH) would have occurred in the first place in the individual ( P(PH WHOIFPI) ) can be calculated as follows: Let's say that the last blood test taken by

943-424: The first place by other candidate conditions can be calculated in a similar manner. However, for simplicity, let's say that the probability that any of these would have occurred in the first place is calculated at 0.0005 in this example. For the instance of there being no disease , the corresponding probability in the population is complementary to the sum of probabilities for other conditions: The probability that

984-575: The incidence of cancer in the area is estimated at 1 in 250 per year, giving a population probability of cancer of: For simplicity, let's say that any association between a family history of primary hyperparathyroidism and risk of cancer is ignored, so the relative risk for the individual to have contracted cancer in the first place is similar to that of the population (RR cancer = 1): However, hypercalcemia only occurs in, very approximately, 10% of cancers, (r cancer → hypercalcemia = 0.1), so: The probabilities that hypercalcemia would have occurred in

1025-502: The individual can be calculated as: and for other candidate conditions: and the probability that there actually is no disease: For clarification, these calculations are given as the table in the method description: Thus, this method estimates that the probability that the hypercalcemia is caused by primary hyperparathyroidism, cancer, other conditions or no disease at all are 37.3%, 6.0%, 14.9%, and 41.8%, respectively, which may be used in estimating further test indications. This case

1066-408: The individual would be healthy in the first place can be assumed to be the same: The rate at which the case of no abnormal condition still ends up in measurement of serum calcium of being above the standard reference range (thereby classifying as hypercalcemia) is, by the definition of standard reference range, less than 2.5%. However, this probability can be further specified by considering how much

1107-452: The inspiratory and expiratory phases) indicates narrowing at the level of the glottis or subglottis , the point between the upper and lower airways. Preschool wheezing is a clinical condition that describes wheezing preschool children that do not fulfill the criteria of " asthma " fully as asthma would require a person to demonstrate a history of at least three episodes of exacerbations (worsening of symptoms) or chronic cough or wheeze for

1148-446: The inspiratory phase of respiration usually indicates an upper respiratory tract obstruction, "as with aspiration of a foreign body (such as the fabled pediatric peanut)." Stridor in the inspiratory phase is usually heard with obstruction in the upper airways, such as the trachea, epiglottis, or larynx; because a block here means that no air may reach either lung, this condition is a medical emergency. Biphasic stridor (occurring during both

1189-400: The last half-year because a previously developed hypercalcemia would probably have been caught up by the previous blood test. This corresponds to a probability of primary hyperparathyroidism (PH) in the population of: With the relative risk conferred from the family history, the probability that primary hyperparathyroidism (PH) would have occurred in the first place in the individual given from

1230-416: The measurement deviates from the mean in the standard reference range. Let's say that the serum calcium measurement was 1.30 mmol/L, which, with a standard reference range established at 1.05 to 1.25 mmol/L, corresponds to a standard score of 3 and a corresponding probability of 0.14% that such degree of hypercalcemia would have occurred in the first place in the case of no abnormality: Subsequently,

1271-509: The occlusion of a portion of the respiratory tree, are more likely to produce wheezing at that location, hence the sound will be loudest and radiate outwardly. The pitch of a wheeze does not reliably predict the degree of narrowing in the affected airway. A special type of wheeze is stridor . Stridor — the word is from the Latin, strīdor — is a harsh, high-pitched, vibrating sound that is heard in respiratory tract obstruction. Stridor heard solely in

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1312-423: The only information given in the medical records is a family history of primary hyperparathyroidism (here abbreviated as PH), which may explain the finding of hypercalcemia. For this patient, let's say that the resultant hereditary risk factor is estimated to confer a relative risk of 10 (RR PH = 10). The clinician considers that there is enough motivation to perform a differential diagnostic procedure for

1353-448: The past six months. Besides, a number of wheezing preschool children would have their symptoms resolved after they had grown up, unlike asthma which persists into adulthood. Preschool wheezing can be divided into "viral-induced wheeze" and "multi-trigger wheeze". Viral-induced wheezing accounts for about two-thirds of all preschool wheezes. The wheezing symptom is episodic and the child is completely normal in between wheezing episodes. It has

1394-499: The patient from delays, risks, and cost of inefficient strategies or tests. Effective providers utilize an evidence-based approach, complementing their clinical experience with knowledge from clinical research . A differential diagnosis has four general steps. The clinician will: A mnemonic to help in considering multiple possible pathological processes is VINDICATEM : There are several methods for differential diagnostic procedures and several variants among those. Furthermore,

1435-467: The patient was half a year ago and was normal and that the incidence of primary hyperparathyroidism in a general population appropriately matches the individual (except for the presentation and mentioned heredity) is 1 in 4000 per year. Ignoring more detailed retrospective analyses (such as including speed of disease progress and lag time of medical diagnosis ), the time-at-risk for having developed primary hyperparathyroidism can roughly be regarded as being

1476-476: The patient's peak expiratory flow rate is less than 50% of normal. Wheezing heard in the inspiratory phase, on the other hand, is often a sign of a stiff stenosis, usually caused by tumors , foreign bodies or scarring. This is especially true if the wheeze is monotonal , occurs throughout the inspiratory phase (i.e. is "holoinspiratory"), and is heard more proximally, in the trachea . Inspiratory wheezing also occurs in hypersensitivity pneumonitis. Wheezes heard at

1517-452: The potential presence of candidate diseases or conditions can be viewed as hypotheses that clinicians further determine as being true or false. A differential diagnosis is also commonly used within the field of psychiatry / psychology , where two different diagnoses can be attached to a patient who is exhibiting symptoms that could fit into either diagnosis. For example, a patient who has been diagnosed with bipolar disorder may also be given

1558-411: The presentation has occurred by 100% certainty in the individual. Yet, the contributive probability fractions of each condition are assumed the same, relatively: where: When an individual presents with a symptom or sign, Pr(Presentation has occurred in individual) is 100% and can therefore be replaced by 1, and can be ignored since division by 1 does not make any difference: The total probability of

1599-417: The presentation to have occurred in the individual can be approximated as the sum of the individual candidate conditions: Also, the probability of the presentation to have been caused by any candidate condition is proportional to the probability of the condition, depending on what rate it causes the presentation: where: The probability that a condition would have occurred in the first place in an individual

1640-421: The probability that hypercalcemia would have resulted from no disease can be calculated as: The probability that hypercalcemia would have occurred in the first place in the individual can thus be calculated as: Subsequently, the probability that hypercalcemia is caused by primary hyperparathyroidism (PH) in the individual can be calculated as: Similarly, the probability that hypercalcemia is caused by cancer in

1681-401: The situation is less acute, a more comprehensive differential diagnostic procedure may be adopted. The differential diagnostic procedure may be simplified if a " pathognomonic " sign or symptom is found (in which case it is almost certain that the target condition is present) or in the absence of a sine qua non sign or symptom (in which case it is almost certain that the target condition

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