(1)
Hôpital Ambroise Paré Service de Réanimation Médicale, Boulogne (Paris-West University), France
The lung is the main vital organ, and the child is our most precious priority. Any concept which could link the lung and the child is therefore of interest. Up to now, the usual tool is the radiograph. CT should be more accurate one guesses, yet its radiation hazards are difficult to accept here [1–4].
How about using ultrasound, lung ultrasound, a non-irradiating technique, repeatable at will, in the neonate? Born for the privilege of having completed an experience in the critically ill neonate, this chapter will see how LUCI can be introduced in this precious setting. We will demonstrate, without gold standard, why it is possible and urgent to implement lung ultrasound in the neonate.
A 5 MHz microconvex probe will maybe not be sufficient in very small children. Frequencies such as 8–12 MHz should probably be preferred. The use of a high frequency offers the finest resolution.
Lung Ultrasound in the Newborn: A Major Opportunity
The bedside chest radiography is the usual tool used for assessing the neonate’s lung. This is striking to see that (without deep mistake) this tool was never assessed. All conclusions can therefore be drawn. In the adult, the bedside radiograph has a rough sensitivity of two-thirds for life-threatening disorders [5].
It is classical (and correct) to say that the child is not a miniature adult. But is it true as regards lung ultrasound? In particular, would pneumothorax generate the same signs? Would the edematous interlobular septa of a neonate (10 or 20 times smaller than the adult) generate the same B-lines? Interstitial changes are hardly visible in adult radiographies, this is worst in neonates.
Rare works had the opportunity to overcome the obstacle of the reviewing processes in this sensible setting [6–10], while we were stuck with the task of submitting just the signs of lung ultrasound before being able to reach the following step: showing their relevance [11–13]. We congratulate these authors, hoping our underground work has helped a little.
We analyzed newborns (35± days) admitted in a PICU after cardiac surgery, for 3 years. We used the technique and semiotics described, assessed, and standardized in the adult.
We took maximal care avoiding crossed infections. This is quite impossible with most machines, since the profusion of buttons and probes makes futile any attempt of cleaning.
We avoided the use of Doppler, since we are still not confident on the absence of side effects [14–16].
We had no choice but using a Philips Sonos 5500 (Philips, Andover, Netherlands) unit with a phased array 12 MHz probe. This was not ideal for many reasons. By fully exploiting our previous experience, it was possible to draw conclusions, but we guess young users would have found more difficulties.
An acronym for such an application? Read our comments in Chap. 37.
The Design of Our Study
We assessed whether the ten signs that make lung ultrasound in the adult were found again in the newborn:
1.
The pleural line (with the bat sign)
2.
The A-lines
3.
Lung sliding (with the seashore sign)
4.
The quad sign (with the lung line)
5.
The sinusoid sign
6.
The tissue-like sign
7.
The shred sign
8.
The B-lines
9.
Lung sliding abolished (with the stratosphere sign)
10.
The lung point
Basic Technique
The BLUE-points, described in Chap. 6, are used with no adaptation (Fig. 32.1). They replace previous landmarks (Accessory Note 1). Lung ultrasound in the neonate is more easy than in the adult. The 8-cm length of the probe is relatively long here, for the PLAPS-point investigation, but the light weight of the baby makes easier the rotation of the thorax (keeping in mind the fragile endotracheal tube).
Fig. 32.1
The BLUE-points in the neonate. This figure shows a simple way to determine the anterior chest wall. One takes the size of two hands of the baby, side by side, without thumbs, from the lower border of the clavicula. The lower finger indicates the lower end of the lung (note that the left hand (white frame) is in a nearer plane, and we corrected the projection of the hand for the need of the picture)
The Signs of Lung Ultrasound (Seen and Assessed in Adults) and Rough Results
Basic normal signs: Signs N° 1–3
The pleural line (with the bat sign) was found in all examinations (Fig. 32.2). Lung sliding was either present (with the seashore sign) or abolished. The A-lines were visible in enough cases to note that a newborn lung surface was able to generate A-lines.
Fig. 32.2
Normal lung surface (A-profile) in the neonate. Left: as in the adult, the ribs of the mature neonate give acoustic shadows, and a bat sign can be depicted, with proportions identical to the adult. In this child, the pleural line between two ribs is visible through 9 mm, and the rib line/pleural line distance is 2.5 mm. The fine horizontal arrows indicate A-lines. Right: a seashore sign, exactly similar to an adult’s one. Note the Keye’s sign (also similar to the adult’s one), above the pleural line (arrow). All these data indicate that this child has a (quarter of) A-profile, meaning that the BLUE-protocol may be applied to children (Image acquired with a Hewlett-Packard Sonos 5500)
Pleural effusion: Signs N° 4 and 5
The quad sign and the sinusoid sign were found in some cases (Fig. 32.3). It was possible to make precise measurements. Further studies should convert these measurements into volumes, using standardized points.
Fig. 32.3
PLAPS in the neonate. From top to bottom: the large arrows indicate the pleural line. The small white arrows indicate a lung line, demonstrating a (small) pleural effusion. Surrounded by the black arrows, a tissular pattern with a shred sign, i.e., a lung consolidation. Example of PLAPS (detected at the PLAPS-point). Once again note the poor resolution quality (Image acquired with a Hewlett-Packard Sonos 5500)
Lung consolidation: Signs N° 6 and 7
All signs described in the adult were present, i.e., the tissue-like sign, the shred sign, the air bronchograms, the dynamic air bronchograms, etc. (fluid tubulograms and others) (Fig. 32.3). They were seen in more than half the cases. A BLUE-consolidation index was available for each. Regarding the mediastinal line, the distance with the pleural line, 9–11 cm in adults, should be here (as well as in adults) four times the length of the pleural line.
Interstitial syndrome: Sign N° 8
The characteristic sign of interstitial syndrome, i.e., the disseminated lung rockets, were recorded in many cases (Fig. 32.4).
Fig. 32.4
Lung rockets in the neonate. Massive lung rockets at a neonate’s lung surface, as in the adult, indicating an interstitial disorder (inflammatory lung syndrome after cardiac by-pass) (Image acquired with a Hewlett-Packard Sonos 5500)
Pneumothorax: Signs N° 9 and 10
The A′-profile and the lung point were observed in a few cases.
The profiles of the BLUE-protocol
It is too early to affirm that the BLUE-protocol works in the neonate. Just note that all its profiles were seen again in critically ill neonates: we saw all BLUE-profiles dispatched among these babies, by order of increasing frequency: the B, A/B, C, A then B′ profiles. We let the physicians either imagine what they can infer from these data or drive any necessary studies using any appropriate gold standard.
Demonstration of the Potential of Ultrasound to Replace the Bedside Radiography as a Gold Standard
We found in this series roughly the same discrepancy than the one long highlighted in the adult (where CT clearly demonstrated ultrasound’s superiority). Our experience has no solid gold standard such as CT, and we expect many rejections of our work (warning on the value of bedside chest radiography in the light of ultrasound data).
When two tests disagree, one is right, one is wrong, without space for intermediate possibilities in one given patient. We propose two ways (one logical, one scientific) for demonstrating the superiority of ultrasound, even without a gold standard.
For the Hurried Reader, the Logical, and Intuitive Proof
Our 3-year experience driven in a neonate ICU showed that the 10 basic, standardized signs that were assessed in the adult (who benefited from CT correlations) were all found again in critically ill newborns. During all this observation, we did not see any “new” sign particular to the neonate that had not been observed previously in the adult. What else to add? When finding a fractal sign, which disease to expect (but a non-translobar lung consolidation)?
For Non-hurried Readers, a Scientific Proof
Here is a ten-step demonstration. In spite of the absence of CT correlation, the discrepancy found between radiography and ultrasound should favor ultrasound.
Step 1: The ultrasound signs assessed in the adult are exactly the same in the neonate
See our comments just above (“for the hurried readers”).
Step 2: A discrepancy between ultrasound and radiography is highlighted in the critically ill neonate
Our experience in neonates showed that the correlation with the radiography, read by skilled blinded radiologists, made appear a discrepancy in roughly the same proportions as the one long observed in adults – where CT clearly showed ultrasound’s superiority.
Step 3: The anatomic features of each syndrome (pneumothorax, etc.) are the same in both adults and neonates
Regarding the assessed disorders, no radiologic distinction was made to our knowledge between adults and children [17]. There is no physiopathological argument for assuming that these two populations should generate different radiologic patterns [18]. The same reasoning is valuable as regards ultrasound. This is the only speculation of our demonstration.
Step 4: Adult bedside chest radiography is imperfect
The limitations of radiography have been clearly demonstrated in the adult [19–27] (Table 32.1).
Table 32.1
Accuracy of radiography compared to CT in the adult ARDS
Sensitivity (%)
Specificity (%)
Pleural effusion
39
85
Lung consolidation
68
95
Interstitial syndrome
60
100
Step 5: Ultrasound has accuracy near to CT in the adult
As opposed, ultrasound proved in the adult a sensitivity and a specificity near to CT [5, 26–32] (see Table 29.3), on occasion superior [33].
Step 6: Bedside radiography in the neonate is a tool which has not been evaluatedRelated posts:
The Excluded Patients of the BLUE-Protocol: Who Are They? Did Their Exclusion Limit Its Value?
Glossary
The Ultrasound Approach of an Acute Respiratory Failure: The BLUE-Protocol
Lung Ultrasound Outside the Intensive Care Unit
The BLUE-Points: Three Points Allowing Standardization of a BLUE-Protocol
Which Equipment for the BLUE-Protocol 2. The Probe
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