The LUCI-FLR Project: Lung Ultrasound in the Critically Ill – A Bedside Alternative to Irradiating Techniques, Radiographs and CT

(1)

Hôpital Ambroise Paré Service de Réanimation Médicale, Boulogne (Paris-West University), France

The most severely ill patients are the ones who can benefit less from CT or MRI. Critical ultrasound and lung ultrasound neatly solve this weird paradox while limiting medical radiations.

The target of the LUCI-FLR project is to decrease in the three next decades bedside radiographies by 1/3 and urgent CT by 2/3.

Some academicians have found that lung ultrasound was a futile idea in light of the technological advances of the modern medicine. The ADR-4000 of 1982, with its 45 cm width, was the basis for an absolute, disruptive revolution. At this period, the modern technologies were not mature. CT, D-dimers, and BNP, all these wonderful helps, did not exist. At this remote period, ultrasound mastered countless clinical situations, and those who used this tool first, although working in quite “clandestinity,” had a huge advance for night or day management of critically ill patients. Critical ultrasound, more than simple images, allowed to take immediate decisions. Today, it is true, the contrast between ultrasound and the rest is less “spectacular” (Fig. 29.1) but remains substantial. In other words, ultrasound currently makes a revolution, but it could have been a historical one. The community just lost three decades of visual medicine (i.e., blood, sweat, and tears for many, many patients).

Fig. 29.1

LUCI-FLR and decades. This diagram shows that portable ultrasound, quite perfect since 1982 (the ADR-4000) and even possible before the 1974 revolution of real time, could have made a historical medical revolution, the visual medicine at an era where quite nothing existed (1965, the dark era of kidney tomographies, gas encephalocisternographies, those syringes with glass and metal, etc.). Today, the advances in other fields decrease this gap, which still remains substantial – not to deal with the intrinsic advantages of ultrasound (cost, etc.)

In this chapter, we will see some occult drawbacks of CT and why ultrasound can avoid most referrals to this giant of imaging through a program which can be perfectly standardized.

Lung Ultrasound and the Traditional Imaging Standards in the Critically Ill: The LUCI-FLR Project

We saw how lung ultrasound performs better than bedside radiography for most indications in the critically ill. It may seem bold to now compare ultrasound with CT. Yet this is what we do daily.

During decades, thoracic ultrasound appeared limited to the sole diagnosis of fluid pleural effusion [1–3], when this application was not forgotten [4]. The alternative for emergency lung assessment was bedside radiography or CT [5]. Ultrasound elegantly solves this quandary.

The LUCI-FLR project (Lung Ultrasound in the Critically Ill Favoring Limitation of Radiation) is in the field of the possible. Its target is to decrease, in the three next decades, bedside radiographs by one–third and CT by two–thirds. One can go far beyond, but we aim at a reasonable, realistic target. The “L” is for limiting. The idea of some aggressive proselytes (who advocate ultrasound for everything) of eradicating radiography may appear scary – as well as the resulting acronym. Limiting, not eradicating, is the humble target of LUCI-FLR project.

We must keep radiography, this centenary technique [6, 7], for specific indications (need for overview, exact location of central lines, etc.). On the contrary, all questions clearly answered by ultrasound allow to skip X-rays. Just one example: pneumothorax. Each time the only question is “pneumothorax” and the answer is “no,” lung sliding can completely replace any radiograph, to advantage. This means, each time there is a chest pain, a thoracic procedure, a desadaptation of a ventilated patient, in an emergency or more quietly…. i.e., a dozen of disciplines and maybe more. Just imagine [8].

We must be aware of the limitations and inadequacies of bedside chest radiography [9–16]. Basic diagnoses are occulted: pneumothorax (even tension cases), pleural effusions (up to 500 ml), lung consolidation (mostly of the lower lobes), and interstitial syndrome (this diagnosis is even not required from a bedside radiograph). The summation of the images makes the disorders difficult to interpret. Some excellent radiologists know how to read some bedside radiographs, but they are not available 24/7/365 in small, nonuniversity-affiliated hospitals. We have evidence that the study of the ten ultrasound signs is much easier to acquire. Either the radiography is normal or highly abnormal (white lung), ultrasound immediately discriminates the alveolar, interstitial, and pleural components, not to speak of subphrenic or mediastinal disorders. Radiography is available only within hospitals (read last §). The irradiating potential of radiography is a concern in each pregnant woman, child, or, by extension, any person.

Tables 29.1 and 29.2 detail why ultrasound usually shows what radiography misses.

Table 29.1

Disorders which can be missed or confused with other disorders by bedside radiograph (into brackets, diagnoses that are erroneously done)

	Pleural effusion	Lung consolidation	Interstitial syndrome	Free pneumothorax	Normal subject
False negatives	Retro-diaphragmatic location (normal) Extensive but spread posterior location (normal or alveolar syndrome)	Too small lesion (normal) Consolidation totally hidden by the cupola (normal) Consolidation partially hidden by the cupola with blunting of the cul-de-sac (pleural effusion) Summation of consolidation without air bronchogram with pleural effusion (pleural effusion)	Too small images (normal) Too dense patterns (alveolar syndrome) Summation with posterior pleural and alveolar images (alveolar or pleural)	Pleural line not tangential to the X-rays (normality)	Not applicable
False positives	Basal alveolar consolidation blunting the cul-de-sac	Pleural effusion with diffuse posterior location Some interscissural pleural effusions Summation of pleural images with dense interstitial syndrome	None	None	Interstitial syndrome (if poor inspiration) Pneumothorax (skinfolds)

Table 29.2

Disorders which can be missed or confused with other disorders by ultrasound (into brackets, diagnoses that are erroneously done)

	Free pleural effusion	Lung consolidation	Interstitial syndrome	Pneumothorax	Normal subject
False negatives	(1)	Deep lesion (normal)	(1)	Absence of lung point (2)	(1)
False negatives	(1)	Not scanned location (normal)	(1)	Absence of lung point (2)	(1)
False positives	(1)	(3)	(4)	(1)	(1)

(1) No condition yet considered

(2) In the case of an A′-profile without a lung point, we remind it is preferable for ultrasound not to conclude

(3) In our previous edition, we featured the thymus and some loculated and echoic pleural collections, but both are distinguished using the thymus line and the lung line, which are not confused with a shred line

(4) The exceptional gooey sign, described in Chap. 12

Overt and Occult Drawbacks of Thoracic Tomodensitometry

The CT is a giant in imaging. It has the major advantage of providing an easy-to-interpret overview of the chest. We respect this precious tool which has saved many lives. For giving a chance to ultrasound facing this standard, we remind seven of the CT’s drawbacks:

Cost (machine, maintenance, etc.).

For us, this is a minor problem. For more than 2/3 of the people on Earth (far more), who will never see a CT, this is a critical, life-threatening issue.

Irradiation.

We who have the privilege of affording CT in each of our wealthy institutions must now face its high degree of irradiation: 400 times (or more?) that of a chest radiography. Deleterious side effects of CT are now acknowledged [17–21]. Investigation of lung disorders in pregnant women raises concerns [22]. Diagnostic X-rays are the largest source of artificial radiation exposure, the source of 0.6–3.2 % of the cumulative risk of cancer [19, 20]. A CT performed at the chest of a 30-year-old or less woman increases the risk of breast cancer by 35 % [23]. A CT done before the age of 1 year accounts for 3 % of radiation-induced cancers and between 1 and 14 years for 19 % [19]. Authors increasingly point out the drawbacks of chest CT, but without proposing any real alternative [24]. Ultrasound provides an elegant solution.

Delay.

Some experts found lung ultrasound a minor idea, since CT provides all answers in “10 s.” Brackets. This vision has resulted in countless rejections, delaying publications, limiting the widespread of a simple approach, with the consequences we can all live now (a whole community equipped with machines which are good, but could have been acquired much sooner, and with more interesting performances). But it is far from true. While lung ultrasound was fully implementable, i.e., since 1982 (or less), the CT machines were in their infancy. The image acquisition was long – a deadly issue for some patients. Just for those patients who survived to CT, while bleeding actively, how many blood units were lost. Countless. Rivers of blood. Yet now that CTs are so-called rapid, the real overall time is not “10 seconds.” When the managing team comes to the point that a CT is necessary in a given unstable patient, the time for arguing with the radiologist, preparing the patient, moving the patient to the CT department and then on the CT table, waiting the famous 10 s acquisition, understanding the CT results, taking the patient back to the ICU, and being able to manage the disorder according to the CT result, this time is superior to “10 s.” Those who can do this incompressible sequence in less than 1 h can contact us.

Need for transportation.

This is a major drawback in the critically ill. In the intensivist’s brain, requiring CT scan is a decision.

An unstable patient is at permanent risk. Multiple life-support devices (catheters, tubes) can be harmful.
Transportation of unstable patients is a strain for the whole medical and paramedical team.
The intensivist is condemned to doing nothing during the entire procedure and cannot deal with other emergencies. It should be recalled here that during more than 12 h a day (including the whole night), only one intensivist is present for the hospital’s extreme emergencies.
Emergency CT scan is not the time to warrant perfect asepsis – the critically ill patient with multiresistant germs behaves as a “bacteriologic bomb” for the whole hospital.