**6. Endotracheal tube**

radiation improves quality of care as well as patient safety [16]. Neonatal lung POCUS is similar to pediatric lung POCUS except that the neonate has very thin soft tissue in the chest with thin ribs and a cartilaginous sternum that enables larger windows of viewing. From a technical perspective, we need a high frequency transducer like a 7–15 MHz hockey stick or equivalent linear array transducer. The detection of common respiratory conditions has been documented making it potentially possible to define the parenchymal lung disease by characteristic patterns to the common respiratory conditions such as pneumonia (PNA), transient tachypnea of the newborn (TTN) and respiratory distress syndrome (RDS). The ability to make an urgent diagnosis is where the greatest utility of lung POCUS may lie as acute respiratory compromise often requires rapid diagnostics. The presence of air or fluid such as blood,

The complication of spontaneous pneumothorax (PTX) at birth is one such condition that may be aided by lung POCUS. PTX will display several differing US patterns compared to normal lung. The characteristic findings on US of PTX in neonates are similar to adults and children (**Figure 4**). Normal lung appears homogeneous in texture with the occasional presence of hyperechoic linear A (horizontal) and B (vertical) lines. Movement of the parietal and visceral pleura against each other during respiration creates a "shimmering effect" or an "ants marching effect" which is termed lung sliding. The presence of the sliding lung sign rules out a pneumothorax on B mode [17]. Further confirmation of a PTX can be achieved with M mode which displays the data from a single line in an image mapped against time on the x-axis. The appearance of moving lung tissue results in a granular appearance similar to a sandy "seashore" with the "waves" at the top representing the static soft tissue above the lungs.

The underlying changes in RDS involve loss of the smallest airspaces (alveoli or saccules). This generates denser tissue that gives the appearance of "white lung" using lung POCUS. Some have proposed a scoring system to categorize lung disease in RDS to assist in increasing specificity for diagnosing RDS [19]. This score can reliably predict the need for surfactant treatment in preterm babies less than 34 weeks gestation treated with nasal CPAP from birth. Several

transudate or exudate in the pleural space is readily discernable by US.

68 Current Topics in Intensive Care Medicine

Some data suggests that US may not be as sensitive for PTX in neonates [18].

**Figure 4.** Pneumothorax (a) normal lung, (b) pneumothorax.

Neonatal intubation remains a difficult high level skill. Although there are much less intubations taking place compared to a decade ago, the need to establish a secure airway remains ever important. This is particularly true for resuscitation of neonates <28 weeks gestation. The current standard of practice to confirm the placement of the endotracheal tube (ETT) is with chest x-ray (CXR).The passage of the ETT into the trachea or esophagus can be discerned readily using a transverse probe position in adults and pediatric subjects [22–25]. POCUS can be used to rapidly and accurately visualize the anatomic position of the ETT position in preterm and term infants [26] (**Figure 5**). Unlike in pediatric or adult patients, evaluating the ETT in the newborn

**Figure 5.** Endotracheal tube placement ETT-endotracheal tube, RPA-right pulmonary artery.

through the chest is possible due to the cartilaginous sternum. Although there is air inside and around the ETT and the entry is at a steep angle to the ultrasound probe, the tip of the probe can be identified with a white or hyperechoic line. The ideal location for the tip of the ETT is midway between the thoracic inlet and the carina. Identifying the distance of the tip of the ETT from the carina can be accurately measured. In a recent publication of an extensive database literature search on studies relating to US use for ETT position confirmation found nine studies which collectively reported a > 80% visualization of the ETT tip by US [22]. Also, US interpretation of the ETT position correlated with the XR position in 73–100% of cases. US appears comparable to XR determining ETT position in this population. As US is more easily available and is safer than CXR, it may be a better modality for confirming proper placement of ETT in neonates when time is critical. There are no current data yet on identifying tip location during placement of the ETT and so more clinical data may be required before widespread adoption.
