Diaphragm ultrasound examination for congenital diaphragmatic eventration in two premature neonates

Abstract

Congenital diaphragmatic eventration (CDE) is always diagnosed by fluoroscopic examination. However, this technique is inappropriate for premature neonates because of risks of transport, hypothermia and ionising radiation. Herein, we describe two cases of premature neonates suspected to have CDE on radiography. We could not perform fluoroscopic examination due to their prematurity status. Therefore, we performed ultrasound examination and succeeded in diagnosing CDE without any risks. Using ultrasound examination, we could evaluate movement and thickness of the diaphragm. We consider this additional information useful for CDE diagnosis. This is the first report on CDE diagnosis using ultrasound examination.

Background

Congenital diaphragmatic eventration (CDE) is a rare disease in which the diaphragmatic musculature is replaced with fibroelastic tissue because of congenital developmental failure.¹ CDE is diagnosed by fluoroscopic examination, and histopathological examination is not routinely performed.¹ Although fluoroscopic examination is considered the gold standard to assess diaphragm movement,² it requires transportation of the patient to the radiology suite and involves the risks of hypothermia and ionising radiation. Conversely, ultrasound examination can be performed at the bedside without any risks. Herein, we describe two cases of premature neonates who were suspected of having CDE on radiography and diagnosed using ultrasound examination.

We performed the following procedures with an Aplio i800 (TOSHIBA, Japan) as previously reported in paediatric reports.^{1 3–5} Visualisation of the right and left diaphragm was performed simultaneously using a 7-MHz-convex-probe placed in the subxiphoid transverse plane with the probe directed to the 9 o’clock position.² Observation of changes in the diaphragm thickness using a 20 MHz linear probe in the zone of apposition (ZOA), the mid-axillary line between the 8th and 10th intercostal spaces,³ in the longitudinal plane.³ Observation of the diaphragm movement was performed via the M-mode using a 7 MHz convex probe placed between the mid-clavicular line and anterior axillary line in the longitudinal plane, with the liver and spleen as acoustic windows. Subsequently, we measured the excursion of the diaphragm using the average of three respiration cycles.

We obtained written informed consent from the parents of the patients for the publication of this study.

Case presentation

Case 1: A premature male neonate was born at 31 weeks of gestation with a birth weight of 1720 g. He experienced respiratory failure and required respiratory support with mechanical ventilation. Radiography showed an elevated right diaphragm, and we suspected CDE. However, we could not perform fluoroscopic examination because of the risk of transport and hypothermia.

Case 2: A premature male neonate was born at 36 weeks of gestation with a birth weight of 2268 g. He had respiratory failure, and the left diaphragm was observed to be elevated using radiography.

Investigations

Case 1: We performed diaphragm ultrasound examination. When we observed both sides of the diaphragm simultaneously, the movement of the right diaphragm was less than that of the left diaphragm (figure 1A). On observing the ZOA of each side of the diaphragm, the right diaphragm was thinner than the left diaphragm, with a slight change in thickness during the respiration (figure 1B). On observation via M-mode, the excursion of the right diaphragm was less than that of the left diaphragm (figure 1C). The patient was diagnosed with CDE on the basis of fluoroscopic examination at the age of 2 months.

Figure 1.

(A) During inspiration, the left diaphragm moved towards the transducer, but lack of movement of the right diaphragm was noticed (arrow). (B) The diaphragm was visualised as a hypoechoic structure between two hyperechoic lines in the zone of apposition (arrows). From the end of expiration to inspiration, the right diaphragm could not be measured because it was too thin, and the thickness of the left diaphragm changed from 0.92 to 1.54 mm. (C) The left diaphragm showed an average excursion of 5.2 mm. The right diaphragm showed an average excursion of 1.8 mm.

Case 2: We performed diaphragm ultrasound examination as in case 1. We found that the left diaphragm exhibited less noticeable movement, was thinner and had less change in thickness during respiration compared with the right diaphragm (figure 2A–C). He was diagnosed with CDE using fluoroscopic examination on the 16 days of life, and was discharged from the hospital because his respiratory condition improved.

Figure 2.

(A) During inspiration, the right diaphragm moved towards the transducer, but lack of movement of the left diaphragm was noticed (arrow). (B) The diaphragm was visualised as a hypoechoic structure between two hyperechoic lines in the zone of apposition (arrows). From the end of expiration to inspiration, the thickness of the right diaphragm changed from 1.62 to 2.32 mm, and the thickness of the left diaphragm changed from 0.42 to 0.6 mm. (C) The right diaphragm showed an average excursion of 5.0 mm. The left diaphragm showed an average excursion of 2.1 mm.

Treatment

The patient in case 1 underwent diaphragmatic plication at the age of 2 months due to a lack of noticeable improvement in his respiratory failure. The patient in case 2 also underwent diaphragmatic plication at the age of 10 months because of recurrent respiratory infections.

Outcome and follow-up

Following the diaphragmatic plication, radiography revealed a normal diaphragm in both patients. The respiratory failure experienced by the patient in case 1 and the recurrent respiratory infections in case 2 eventually improved.

Discussion

In this study, we show the utility of diaphragm ultrasound examination in premature neonates. First, this imaging technique was considered a useful tool for CDE diagnosis without any risks. Second, by measuring the thickness of the diaphragm, we were also able to obtain additional information compared with fluoroscopic examination.

For CDE diagnosis, we need to compare the movement of both sides of the diaphragm simultaneously. Because premature neonates are very small, we were also able to observe both sides of the diaphragm simultaneously using ultrasound examination.

Although fluoroscopic examination is able to show differences in diaphragm movement, it may be difficult to differentiate CDE from diaphragm nerve paralysis. In this study, we could measure the diaphragm thickness, and we considered this additional information to be useful for CDE diagnosis. Thus, we may need to perform not only fluoroscopic examination but also ultrasound examination for CDE diagnosis.

There are two points to note when performing diaphragm ultrasound examination. First, when there are overlying bowel gases, the left diaphragm observation may be difficult.² Second, because diaphragm movement depends on the respiratory condition,⁴ we performed diaphragm ultrasound examination at rest.

Because the normal range of diaphragm thickness and cut-off points for diagnosis are not standardised, further study is required to establish diaphragm ultrasound examination in neonates.

Learning points.

• Diaphragm ultrasound examination has potential in diagnosis for congenital diaphragmatic eventration without any risks.

• Diaphragm ultrasound examination is suitable for premature neonates in observing both sides of the diaphragm because they are very small.

• We could obtain additional information compared with fluoroscopic examination by measuring the thickness of the diaphragm.