Alberto J. Muniagurria
In an orchestra each instrument that collaborates in the execution of a musical score has a form and a meaning. Similarly, the data or information obtained with the Clinical Method (interrogation, physical examination, laboratory, diagnostic imaging, and special techniques) has a form and meaning.
The doctor is trained to analyze and interpret these forms and meanings to arm them into a known entity or defined disease that is already known in its development, mode of presentation, response to therapy, and signals for its control over time. In opportunities for its definitive resolution or cure, in others for its control and improvement of the quality of life, individualizing the needs of each patient in question, and when both are not possible to accompany the patient in his good death (Euthanasia in Hippocratic meaning).
The etiological diagnosis ( I know) or the original cause of the disease is the desired objective, but very often, in practice, the diagnosis is of the syndrome (heart failure, or renal failure as an example), or of its pathophysiology. Lawrence Weed defined as problems any situation in which the etiological diagnosis is not reached, and yet generates a situation of illness or abnormality. Examples of this are Symptoms and Signs, Syndromes, reactions without apparent cause, emotions not framed in defined psychiatric pictures, special social situations (prison, overcrowding, isolation, special social groups).
Obviously with the establishment of diagnosis, the doctor has defined which is the approach with drug therapy or not, the education of the patient, knowing the prognosis ( I anticipate ). With the armed of problems it is possible to approach the situation and improve it
From basic data to plan
The semiologist, Lawrence Weed, made an interesting contribution in the ordering of the data obtained through the Clinical History (CH) by the clinical Method. This system consists in classifying the different data provided by the interrogation, the physical examination and the special study procedures, according to the clinical relationship between them.
The information provided by the patient is called Subjective Data , while the information obtained in the Physical Examinación (PE) and complementary studies is called Objective Data. The latter are not always safe, as they are influenced by the observer, at her level of training and recognition of the sign, especially on Physical Examination. This is also the case with the levels of certainty of the results of the complementary techniques applied, and their error factors.
The subjective and objective data, once grouped together, make up the basic data of the patient ( Basic Information )
From observation arises the analysis and its interpretation, both processes make up what Weed defines as, Data Elaboration Process.
From the union of the Basic Data with each other, the Problems are configured , they are identified and the List of Problems is constructed. Once they have been identified, a diagnostic, therapeutic and educational plan for the patient is drawn up.
Identification of Problems
A patient consults for pain in the side stitch in the right hemithorax, which increases with inspiration, with fever and with rusty expectoration. Thoracic examination revealed crackles in the same lung base and an inspirational murmur on auscultation. The analysis of these Subjective and Objective data, inductively deductively, suggests a lung-based infiltrate with a patent bronchus. From the articulation of the data, a problem can be obtained, and with this we know the indication to obtain a Chest X-ray as well as laboratory studies to complete the information. X-ray shows lobar condensation ( of a lobe) of the right pulmonary base and the study of blood shows elevation of White Blood cells and Erythrosedimentation Rate. The diagnosis of pneumonic condensation syndrome is established.
In the elaboration it is worth returning to the Basic Data. In this way, once the plan has been implemented, it continually returns to the Basic Data, trying to incorporate others. The evolution of the patient's clinical picture will require, on occasions, the modification of the List of Problems and adjustments to the plan.
The line that follows the process of elaboration, in the reasoning of the doctor, can use paths that are often not fully understood by the layman; above all, if it is taken into account, that each doctor applies his own personal modalities, which vary from doctor to doctor. Despite this, some general guidelines can be described that are always followed and that help the elaboration process. The process of the study and marrow dissection (induction and deduction) of the information provided by the Basic Data.
It is worth remembering the English researcher Sherlock Holmes, when asked by his assistant "What do you need the most to solve the mystery", answers "Watson data, we need data"
First, abnormal phenomena should be identified within the Basic Data, listing Symptoms and Signs, clinical and from complementary studies.
Secondly, an attempt should be made to locate these data anatomically . In the example used, the lung is the likely affected organ.
There are imprecise signs regarding the anatomical location, such as fever, fatigue and depression. In this case, an attempt should be made to explain the process in pathophysiological terms , which is the next step, that is, to give a pathophysiological interpretation to the Symptoms and Signs. The symptom or sign occurs because abnormal mechanisms are activated, which alters normal organic structures. (It should be remembered that the pain symptom is a normal response of the organism to an aggressive cause that produces it. The aggressive causes or mechanisms can be congenital, metabolic, inflammatory, vascular, traumatic, toxic, neoplastic or psychopathological.
Once the pathophysiological mechanism has been detected, a hypothesis about the nature of the problem or disease hypothesis must be raised . In order to carry out this step, it is necessary to know the probable medical pathologies or diseases that may be causing it, relying on the bibliographic search. The greater the experience and information, the more accurate the physician's hypothesis will be.
Those unlikely diseases are discarded for the data obtained and the most possible diagnosis should be chosen from the probable diagnoses. At this level, knowledge of age, sex, race, epidemiology and pathology prevalent in the area, response to medication, etc., etc., must be taken into account. In other words, all the factors that overturn the possibility of diagnosing one way or the other.
The time of evolution must also be taken into account, since a panel installed in 24 hours is not the same as another that takes months of evolution. Likewise, the conditions that put the patient at risk and those that will respond to treatment must be considered. Also consider that it must be resolved at the moment (acute symptoms) and which gives time to evaluate (chronic symptoms).
At this point of the diagnostic evaluation is in the "possibility" stage, there is still a way to go through diagnostic studies that confirm or discard the hypothesis. This is termed aetiological diagnostic medical language .
The hypothesis must be tested through new maneuvers, studies or consultations.
On frequent occasions, perhaps in most Primary Care consultations, the definitive etiological diagnosis is not reached, which is only achieved through pathological, bacteriological or specific laboratory studies. This does not contraindicate starting treatment.
Then it remains to assess the response to treatment
The outlined plan must take into account the patient's view of the disease
The doctor must know what the patient has understood about his illness and about the diagnostic plan, what his feelings are. Continuing with the example, the patient who presented himself has to make an important business the next day, or he has just arrived from abroad where he knows that there is mortality from respiratory infections, or he has a son with an immunological deficit.
Patient education should not be one-way, but with the active participation of the patient, giving him or her space to ask questions and approve the indications. Developing a plan requires a timely patient-physician relationship.
Through this methodology, however, limitations may arise
Limitations of the medical model
Medical diagnosis is fundamentally based on having identified abnormal structures, altered systems and other specific causes, but in numerous circumstances, the patient's complaints do not fall into these categories. Some symptoms do not give the possibility of further analysis and little progress can be made with data such as anorexia or fatigue.
Another situation is a consultation, for example, such as fever and where the planning of the study methods follow a pre-established routine, and the extent of application of that routine will depend on the importance of the Symptom / Sign. In other words, it is not always necessary to put into practice all the studies. Before deciding on a large number of diagnostic studies, it is important to evaluate the medical history in detail and request the indicated analyzes in a progressive and judicious way, which will be increasingly judgmental the greater the experience of the physician.
It should also be considered that, frequently, the reason for consultation is more related to the life of the patient than to his “body.” Numerous reasons (loss of loved ones, work, etc. etc.) affect the mood of the patient. person directly.
Identifying these situations, evaluating responses to them, and studying a plan to better manage them is as important as treating your pharyngitis or gastroduodenal ulcer. Many patients seek the doctor, not to cure an illness but to maintain their health. For them and for most, the item “maintenance of health” can be included when developing their List of Problems, and then the plans to elaborate for this problem will be the prevention and promotion of your health. Diets, physical activity, immunizations, discussion of emotions in various circumstances and recommendations for their safety (use of seat belts, prophylactics, etc., etc.) will be the topics to be developed.
Multiple problems versus Unique problema
One of the s difficulties arise, for which it starts, is to group the Symptoms of the patient in a separate Problem or several.
Taking into account the patient's age helps, since it is probable that the young person has unique diseases, while the older adult is affected by multiple diseases. Symptom presentation time is also helpful, as an example, an episode of pharyngitis a month earlier is probably not linked.
With today's consultation, for fever and stitch pain and cough that began in the last 24 hours.
Injured systems can help group Signs
They can be grouped, an elevated blood pressure, with a sustained and displaced left ventricular impulse, a fundus of eyes with arterial injuries, within the cardiovascular system. The problem to open will be: Hypertensive cardiovascular disease with retinopathy. If the patient also has diarrhea and pain in the lower left abdominal quadrant, that will be the second problem.
There is no single rule to link Symptoms and Signs. This is developed through experience and knowledge.
Until a strep throat is interpreted to precede Rheumatic Fever or Glomerulus Nephritis, sore throat will not be grouped with arthritis, hematuria, or eyelid edema as a Problem.
A group of data difficult to manage
Sometimes the List of Problems is very extensive and must be worked on. It is very likely that there are problems that can be integrated or joined. The questioning helps to uncover and guide the causes. If, for example, chest pain occurs, which increases with exertion and disappears at rest in a few minutes, this leads to cardiovascular or eventually osteoarticular pathology, but it is generally against a digestive cause.
Each of the questions used is important in the orientation of thought. The Problem List summarizes the medical thinking process. Collaborate in building medical reasoning.
Acute and chronic reasons for consultation, health checks
From the beginning of the interrogation and throughout the examination of the patient, the acute, urgent and emergency reasons for consultation must be separated , which must be resolved with different degrees of speed, mediately or immediately, from the chronic ones, which require a calmer order. for its control and monitoring. Another scenario is also created in the Health Controls , which have an organized scheme of medical intervention.
In other words, there is a different medical intervention in each case.
Potentially all data or information, with which the reasoning is constructed, has possibilities of error. By forgetting symptoms on the part of the patient, the sequence of events is altered, important elements are hidden due to embarrassment or false interpretations or denial of reality. Or the doctor also misinterprets, discards important information, stops asking key questions, mistakes the signs when checking, or omits maneuvers from the complete physical examination. Errors can be decreased by repeating a careful routine. Despite this "The hare escapes to the most careful ..."
The quality of the Data can be measured. In evaluating the results, it is essential to consider the certainty, precision, sensitivity, specificity and prevalence of the studies for the different pathologies. (Predictive value)
The accuracy refers to the closeness with which a measure reflects the actual value of an object.
Accuracy refers to the reproducibility of a measurement. The measurement can be true, precise, or both or neither. To take an example, the size of the liver, evaluated by percussion, can vary by 2 or 3 centimeters with the actual size, which shows that percussion is not a very precise method. In turn, percussion percussion indicates a smaller liver size than that detected by liver scintigraphy, which shows that percussion is not a certain method either. Despite this, it is more effective than palpation to estimate liver size.
The sensitivity of an observation is the ability to identify people with a certain abnormality within a group, in which all have that abnormality. When the observation does not allow the abnormality to be detected in the person who has it, the result is considered false negative . A highly sensitive test or method of observation is the one that detects the majority of people with the given abnormality and that has few false negatives.
The specificity of an observation refers to the ability to correctly identify people who do not have the abnormality. When it fails to do so it produces a false positive. A test or method that is 95% specific correctly identifies 95 out of 100 normal people. The other 5% are false positives.
The presence of a breath on auscultation serves as an example to understand this. Most patients with aortic stenosis have a systolic murmur on examination of the aortic area. Therefore, a systolic murmur is a very sensitive criterion for aortic stenosis. But that breath has little specificity. Various conditions can cause a systolic murmur to the normal valve. If the systolic murmur were used as a single criterion for aortic stenosis, many patients would be wrongly classified; or that, many false positive diagnoses would be made
In contrast, a decrescendo, high-frequency diastolic murmur in the aortic area and on the left sternal border is much more specific. Most of this type of murmur is produced by aortic insufficiency, rarely other processes can produce a similar sound.
The predictive value of an observation refers to the ability to correctly predict an abnormality, in the findings of a sign, in a population. Unlike sensitivity and specificity, where by definition the population is affected or not, respectively, the predictive value depends on the prevalence of the anomaly in the population. With the same sensitivity and specificity, the predictive value of an observation increases with prevalence. The chances of being right improve when hypotheses are established about frequent abnormalities in the chosen population, and decrease in the opposite situation.
If a patient consults for fever, headaches, general pain, cough, there are more possibilities (greater predictive value) of being on the right track when talking about influenza during the winter, and even more so in the course of an epidemic. What to establish the diagnosis in the summer.
When you hear a gallop in the distance, think that they are horses, unless you are in a zoo, remember the zebras there!
Unfortunately, medical texts generally do not describe the certainty and precision of the methods and rarely mention the sensitivity and specificity of the observations. Usually these data are not reported. Qualitative judgments, however, are possible and we must try to develop them.
When evaluating a symptom or sign, it is necessary to try to detect how true and precise it is, how sensitive it is, said data, for the diagnosis of an abnormality.
In a population similar to that of this patient, in a similar environment, how prevalent is this abnormality, and therefore, how predictive can this data be?
The interplay in the elaboration process and data collection
The medical student, in his training stage, does not yet have the necessary knowledge to judge which data should be emphasized as basic data. You also cannot emphasize, quickly evaluate, and omit unnecessary information. Because of this, you should collect as much information as possible, which may not be necessary for the experienced doctor.
The reason is the development of an interplay between the elaboration process and data collection, which improves when experience increases.
The student must make a thorough history, and a complete physical examination, as this will be necessary to think about the patient . With the years of practice, the doctor will be guided not only by the methodology he learned but by an elaboration and active reasoning. The experienced doctor begins to formulate his hypotheses from the first moment of the interview; From the beginning, and throughout the exam, he tests the viability of his hypotheses with his questions.
When more sagacity and practice is acquired the elaboration process will affect the data collection. The ability to ask key questions is developed, and the examination is directed at certain areas of the patient, with special care and detail.
Likewise, one must be very careful, since the initial judgments may be wrong, and it is possible that very useful data may be omitted, which may modify the hypotheses. Early or hasty formulation can lead to premature questions being generated in directed questioning, and important parts of the global questioning being missed.
Not every patient needs a complete evaluation, but, especially in the elderly, there can be high blood pressure, dyslipidemia, colon cancer and depression at the same time. This will not be detected if the examination is not thorough and thorough. full.
The complete doctor is one who has an orderly method of work and complies strictly, leaving little room for the "bright sparks" of improvisation.