This is the most FAQ.

The heart is associated to the BLUE-protocol, not integrated (it is fully integrated in the Extended BLUE-protocol; see Chap. 35). Yet users may be disappointed to see that the consideration of this expert science will only slightly increase the value of the BLUE-protocol (clinical data and simple lab tests will increase it much better). This is explained first because the lung data allow to predict the cardiac status and, second, because the cardiac data can sometimes be misleading. This explains why the withdrawal of cardiac information resulted in a slight improvement of the accuracy (from 90.3 to 90.5 %; see the small story at the end of Chap. 24). The third and main reason is that the lung analysis is a direct approach in a patient suffering from the respiratory function. Showing an absence of B-profile demonstrates that the left heart function is normal (or not the actual problem). The BLUE-protocol does not search for a left heart anomaly but for the consequence of this anomaly: pulmonary edema. The detection of the B-profile has shown high accuracy for the diagnosis of hemodynamic pulmonary edema (with rare cases of pneumonia and exceptional cases of chronic interstitial disease). The detection of a non-B-profile was correlated with the absence of pulmonary edema.

We will see in Chap. 35 that the Extended BLUE-protocol takes carefully into account not only simple items from Step 1 (history, age, temperature, physical examination, etc.) and Step 2 (white cells, CRP, etc.) but also the simple emergency cardiac sonography. The B-profile in a young patient with fever, no cardiac history, and a well-contracting left ventricle will be immediately suspected as a “failure” of the BLUE-protocol (brackets because it pretends only at a 90.5 % accuracy with the simplest tools).

We therefore advise to begin the analysis of a blue patient (with no clear clinical orientation) with the lung, confirming or not edema, then simple cardiac sonography. This inversion of priorities means gain of time, since lung ultrasound needs shorter training; has less operator dependencies, less patient dependencies, and less risk of poor windows; and is cheaper. In the same time, the physician is free to initiate a training in traditional echocardiography, which will allow to better understand and manage situations where more information is required. It will indicate for instance the need for emergency valvular repair, but these are not frequent scenarios (and we rarely need to repair a valvular disease in the night).

Some colleagues were intrigued by such a timing [2]. These 3 min (let us concede “less than four” for simplifying) were done by experienced users, precisely in the aim of not interfering with the traditional management. Of course, novice doctors are free to take more time. Three-minute examination was an average timing, allowed when using the fast protocol we defined since 1992: one smart machine, one universal (microconvex) probe, one setting, no Doppler, and our substitute to gel. The lung is superficial. Time for finding windows (unlike “ECHO”) is null. Detection of A-lines or B-lines is immediate. The timing is shortened each time the BLUE-protocol does not require venous analysis or posterolateral lung analysis: B-, B′-, A/B-, or C-profile occurs in 46 % of cases and makes a BLUE-protocol duration inferior to 1 min.

We use the same fast protocol for searching for deep venous thrombosis, using the same probe, the same settings, cross-sectional scan, Carmen maneuver, etc.

Using our contact product makes the time between two regions of interest (e.g., lung and calf veins) <2 s. We keep our soaked compress near our scanned field and can do flash scanning. No time is lost for taking the traditional gel bottle, squeezing it, and applying the gel to areas distant from each other and wiping after.