Gastric Point-of-Care Ultrasound in Acutely and Critically Ill Children (POCUS-ped): A Scoping Review

Abstract

Introduction: Point-of-care ultrasound (POCUS) use is increasing in pediatric clinical settings. However, gastric POCUS is rarely used, despite its potential value in optimizing the diagnosis and management in several clinical scenarios (i.e., assessing gastric emptying and gastric volume/content, gastric foreign bodies, confirming nasogastric tube placement, and hypertrophic pyloric stenosis). This review aimed to assess how gastric POCUS may be used in acute and critically ill children.

Materials and methods: An international expert group was established, composed of pediatricians, pediatric intensivists, anesthesiologists, radiologists, nurses, and a methodologist. A scoping review was conducted with an aim to describe the use of gastric POCUS in pediatrics in acute and critical care settings. A literature search was conducted in three databases, to identify studies published between 1998 and 2022. Abstracts and relevant full texts were screened for eligibility, and data were extracted, according to the JBI methodology (Johanna Briggs Institute).

Results: A total of 70 studies were included. Most studies (n = 47; 67%) were conducted to assess gastric emptying and gastric volume/contents. The studies assessed gastric volume, the impact of different feed types (breast milk, fortifiers, and thickeners) and feed administration modes on gastric emptying, and gastric volume/content prior to sedation or anesthesia or during surgery. Other studies described the use of gastric POCUS in foreign body ingestion (n = 6), nasogastric tube placement (n = 5), hypertrophic pyloric stenosis (n = 8), and gastric insufflation during mechanical ventilatory support (n = 4). POCUS was performed by neonatologists, anesthesiologists, emergency department physicians, and surgeons. Their learning curve was rapid, and the accuracy was high when compared to that of the ultrasound performed by radiologists (RADUS) or other gold standards (e.g., endoscopy, radiography, and MRI). No study conducted in critically ill children was found apart from that in neonatal intensive care in preterms.

Discussion: Gastric POCUS appears useful and reliable in a variety of pediatric clinical settings. It may help optimize induction in emergency sedation/anesthesia, diagnose foreign bodies and hypertrophic pyloric stenosis, and assist in confirming nasogastric tube placement, avoiding delays in obtaining confirmatory examinations (RADUS, x-rays, etc.) and reducing radiation exposure. It may be useful in pediatric intensive care but requires further investigation.

Keywords: POCUS; foreign body; gastric insufflation; hypertrophic pyloric stenosis; nasogastric tube; pediatric anesthesia; pediatric emergency; pediatric intensive care.

Figure 1

Prisma flow chart.

Figure 2

Literature search and main findings.

Figure 3

Gastric POCUS to assess gastric volume and content. (A) Empty stomach. (B) Full stomach (liquid content). Curvilinear low-frequency (2–5 MHz) or high-frequency linear transducers were used for examination (the former providing better scanning in older children). The gastric antrum was scanned in the epigastric sagittal plane, in the supine and/or in the right lateral decubitus position, for qualitative assessment and/or for the measurement of the antral cross-sectional area. In some studies, a longitudinal scan of the stomach was performed, allowing measurement of 3 diameters (anteroposterior, transverse, and longitudinal axes) for the calculation of the spheroid stomach volume (43, 44, 46). Repeated measurements minimize intra-rater variability. Gastric content volume was calculated in four studies using the mathematical model by (52) (R² = 0.60), and in one study, it was calculated using the mathematical model by Schmitz et al. (7) (R² = 0.582).

Figure 4

Intragastric foreign body. Large hyperechoic mass within the stomach may suggest the diagnosis of an intragastric foreign body (e.g., voluminous trichobezoar). In an uncertain diagnosis, and before surgery, an abdomino-pelvic CT scan should be performed to examine the extension of the foreign body. Gastric POCUS techniques found in the literature: various ultrasound probes have been used (high- or low-frequency linear or curvilinear transducers) and the child was positioned in a supine and/or a right lateral decubitus to enhance the quality scanning of the thoracic and epigastric areas. Liquid filling may help in visualizing the foreign body.

Figure 5

Intragastric nasogastric tube (or orogastric tube). The gastric POCUS technique found in the literature: The NGT was visualized using the curvilinear transducer or the phased transducer (with the iScan feature to optimize the view). Probe frequency was adapted to the size of the patient. The child was positioned in a dorsal decubitus position. The transducer was positioned in the middle of the epigastric region, allowing for visualization of the tube passing through the cardia and entering the gastric area. Then the transducer was positioned in the upper right quadrant toward the duodenum, to verify whether the tube was entering the pylorus. The correct position of the NGT corresponded to a hyperechogenic line passing through the cardia with its length continuing within the gastric area but not entering the pylorus. Otherwise, the transducer was placed transversely over the xiphisternum and was fanned downward and aimed toward the left upper quadrant to visualize the gastric body through the left lobe of the liver. Then, sagittal and transverse sweeps were performed over the epigastric area. If the NGT was not identified, the transducer was placed over the left flank in the sagittal position using the spleen as a window. The study was considered positive when the NGT could be visualized in the stomach as two parallel hyperechoic lines.

Figure 6

Hypertrophic pyloric stenosis. Gastric POCUS consisted of the measurements of pylorus muscle thickness and length, and HPS diagnosis was confirmed if they were >3 and 15 mm, respectively. A 6–10 MHz linear probe in a transverse position allows identifying the gallbladder in the supine position. The pylorus is usually located slightly medial and posterior in relation to the gallbladder.