Novel aspects in diagnostic approach to respiratory patients: is it the time for a new semiotics?

Abstract

Medical approach to patients is a fundamental step to get the correct diagnosis. The aim of this paper is to analyze some aspects of the reasoning process inherent in medical diagnosis in our era. Pathologic signs (anamnestic data, symptoms, semiotics, laboratory and strumental findings) represent informative phenomena to be integrated for inferring a diagnosis. Thus, diagnosis begins with "signs" and finishes in a probability of disease. The abductive reasoning process is the generation of a hypothesis to explain one or more observations (signs) in order to decide between alternative explanations searching the best one. This process is iterative during the diagnostic activity while collecting further observations and it could be creative generating new knowledge about what has not been experienced before. In the clinical setting the abductive process is not only theoretical, conversely the physical exploitation of the patient (palpation, percussion, auscultation) is always crucial. Through this manipulative abduction, new and still unexpressed information is discovered and evaluated and physicians are able "to think through doing" to get the correct diagnosis. Abductive inferential path originates with an emotional reaction (discovery of the signs), step by step explanations are formed and it ends with another emotional reaction (diagnosis). Few bedside instruments are allowed to physicians to amplify their ability to search for signs. Stethoscope is an example. Similarities between ultrasound exploration and percussion can be found. Bedside ultrasonography can be considered an external amplifier of signs, a particular kind of percussion and represents a valid example of abductive manipulation. In this searching for signs doctors act like detectives and sometimes the discovering of a strategic, unsuspected sign during abductive manipulation could represent the key point for the correct diagnosis. This condition is called serendipity. Ultrasound is a powerful tool for detecting soft, hidden, unexpected and strategic signs.

Keywords: Abduction; Chest ultrasonography; Diagnostic approach; Lung; Semiotics; Ultrasound.

Fig. 1

Seventy-five old man with persistent cough, shortness of breath of recent onset and ankle edema. a: Small transonic pleural effusion on the right side. b: Pneumogenic Interstitial Syndrome. The pleural line is irregular and the sub-pleural plane is white, without horizontal reverberations and mirror effect. c: Inferior cava vein is enlarged without inspiratory collapse. d: Sub-xiphoidal view of the heart showing enlarged right ventricle (arrow) with thickened wall. The left ventricle is normally kinetic

Fig. 2

Chest x-ray of the same patient showing enlarged cardiac shadow and uncertain signs of pleural effusion and interstitial lung disease

Fig. 3

a and b: Chest x rays showing two patients with opaque right hemithorax. c and d: ultrasound scans of the right hemithorax in the same patients. The diagnosis is immediate (hyper-codified abduction). a. massive pleural effusion. b: right lung atelectasis. The right main bronchus is closed by a large hilar mass

Fig. 4

Stages of abduction and its iterative dynamics, searching for the best explanation (27, modified)

Fig. 5

a: patient with right pleural effusion, plain chest x-ray. b and c: Bedside Chest ultrasonography strategically revealing nodular variations of the parietal pleura, diaphragm and costophrenic sinus. This serendipitous finding immediately orients towards the most likely diagnosis (neoplastic pleural involvement)