The most basic example, charicaturally simple but significant, is the consideration of fever. Fever is an important and not important data. Let us take the example in the title. The small branch, at the left of the BLUE-protocol decision tree, drives to the B-profile and concludes to hemodynamic pulmonary edema. With scientific reserves: “only” 95 % specificity. The few cases of B-profile that do not come from a hemodynamic cause are some pneumonia, and chronic interstitial diseases, mainly. The Extended BLUE-protocol just aims at improving this rate of 95 % by diagnosing these few cases. We remind that in the absence of a B-profile, there is no hemodynamic pulmonary edema, and the need for a sophisticated “ECHO” should not generate exaggerate energy.

This part of the B-profile can be refined, precisely by adding fever, at this step. If fever was really discriminative, things would be simple: dyspnea with fever is pneumonia. Yet medicine is medicine. Because of previous antibiotherapy, or comorbidities, of limit value of temperature, because some say that fever is “often” seen in hemodynamic pulmonary edema, or any other confusing factor, things are less simple. Here, the BLUE-protocol becomes interesting. The inclusion of the item “fever” there, once a B-profile detected, may add points. It should not be done at every step: for instance, the A-profile plus DVT with, or without, fever remains a pulmonary embolism. Yet the B-profile with fever is not the most typical from pulmonary edema. Here, a fever makes a simple and efficient alert. The consideration of this basic piece of information, of never yet debated interest, can refine this small branch of the B-profile that drives, usually, to hemodynamic pulmonary edema (Fig. 35.2).

This is the simplest example of what is, basically, the Extended BLUE-protocol. Works should of course specify the discriminative value of the temperature (37°8? 38°2?). Hundreds of examples can be added here for the relevance of the physical examination, we let the book as thin as possible.

The consideration of the volume of lung consolidation should matter. A respiratory failure due to pneumonia on healthy lungs (i.e., not including patients with previous chronic respiratory insufficiency), generates a rather substantial volume of excluded lung tissue. The volume of consolidation is usually limited in pulmonary embolism. This can make another small branch in the E-BLUE-protocol (Fig. 35.3).

Once again, we consider the branch driving to the B-profile. In exceptional cases, a chronic interstitial disease can be the diagnosis. By inserting the item “right ventricle enlargement with thickened free wall and well contractile left ventricule” (RVETFWWCLV), the few patients having a B-profile coming from a chronic interstitial disease would be immediately detected – and the therapy would be adapted. Note that colleagues not making lung ultrasound but making echocardiography instead would see a “right” disease, but they would not be able to discriminate a bronchial disease (COPD, etc.) from a chronic interstitial disease (especially when radioccult), which requires other therapies.

The exudative process invades the subpleural interlobular septa and sticks the lung (like countless small nails) to the chest wall. This explains the frequent B’-profile of ARDS [4]. Facing diffuse interstitial edema, the BLUE-protocol distinguishes patients with lung sliding (suggesting transudative process) from those with abolished lung sliding (indicating exudative process).

Infectious processes, including ARDS, can widespread through airway routes, according to non-hemodynamic rules, and the gravity law is less expressed here. This is why lung consolidations can develop anteriorly (the C-profile). The C-profile cannot be seen in AHPE (see pathophysiologic discussion, and Fig. 24.​1). The term of “enlarged” B-profile indicates that the user went beyond the four anterior BLUE-points and made a liberal scanning, searching for C-lines, even minute, not finding any. If a C-line is found, the classification changes, from the B-profile to the C-profile. And the diagnosis is shifted from AHPE to pneumonia.

Asymmetry can be seen if the disorder comes from one lung infection, which explains A/B profiles. An extended definition of the A/B profile includes, at the same lung, areas of predominant lung rockets with areas of predominant A-lines. Unilateral hemodynamic pulmonary edema? These famous cases are very rare, and this is a radiological definition – our very few observations showed more PLAPS at the edematous side, but a symmetrical (anterior) B-profile. To be confirmed on large series.

Most of these patients have lateral lung rockets. This may be considered as an extreme variant of an A/B-profile, i.e., anterior areas without and lateral areas with interstitial patterns. Fluids in AHPE, submitted to hydrostatic pressure, move up actively to the anterior areas through the interlobular septa – toward the sky. Fluids in permeability-induced edema passively descend to the dependent areas (principle N°2 of LUCI). White X-rays with absence of anterior lung rockets are therefore suggestive of ARDS.

Some cases of pneumonia are expressed by a diffuse interstitial injury with no, or not yet, impairment of lung sliding (B’-profile) or anterior consolidation (C-profile). Because of a low accuracy, this profile is not considered as indicating pneumonia in the design of the BLUE-protocol (which, reminder, provides profiles with a high likeliness of diseases, rarely a 100 % certitude, read cartouche of the native decision tree, Fig. 20.​1). Other tools can be added, in the order of the E-BLUE-protocol: from clinical, LUCI, simple emergency cardiac sonography, and interventional ultrasound data, up to classical tests if needed.