CHARACTERISTICS OF BOWEL SOUNDS IN PRETERM INFANTS OF DIFFERENT POST-CONCEPTIONAL AGE
Authors: Mavropulo T. , Khorosh A. 
Published: November 2024

Assessment of the intestinal status of preterm infants is key to early diagnosis of potentially dangerous conditions. Decreased or absent bowel sounds during a short period of observation may indicate serious conditions such as sepsis or necrotizing enterocolitis (NEC) in newborns. The method of detecting bowel sounds using an electronic stethoscope can be used to obtain visual waveforms, which leads to increased objectivity in the analysis of bowel sounds. However, there are currently insuffi cient data to characterize normal bowel sound activity in preterm infants requiring enteral nutrition. The purpose of our study was to investigate the characteristics of bowel sounds obtained by electronic auscultation in preterm infants as a function of postconceptual age (PCA) and enteral feeding status.Materials and methods. A prospective study of premature infants was performed. Inclusion criteria: gestational age (GA) of newborns 24-32 weeks, birth weight up to 1500 g. Exclusion criteria: confi rmed intestinal diseases that would contraindicate long-term enteral nutrition (EN), including congenital anomalies of the gastrointestinal tract, NEC stages 2A-3B; congenital malformations of other organs and chromosomal anomalies; critical condition of the child requiring vasopressor support. The fi rst group included 16 children who received EN in increasing volume (from 10 ml/kg/day to 160 ml/kg/day). The second group included 9 neonates who did not receive EN due to temporary contraindications. Children required invasive or noninvasive lung ventilation, total or partial parenteral nutrition. Electronic auscultation of bowel sounds was performed with a 3M™ Littmann® CORE 2 Digital Stethoscope. The study was performed between 30 and 120 minutes before and after the administration of enteral milk through a nasogastric tube, or once daily if the infant was not enterally fed. A continuous 60-second recording of bowel sounds was obtained, digitally recorded, manually counted, and reviewed for patterns of bowel sounds. The bowel sounds obtained were classifi ed according to the classifi cation of Siok Siong Ching and Yih Kai Tan. The following types of sounds were identifi ed: isolated, grouped, and prolonged. The interval between sounds was determined by the time between the end of one sound and the beginning of the next. Recordings were analyzed in terms of PCA: 26-28 weeks, 28-31 weeks, 32-33 weeks, 34-36 weeks.Results. We analyzed 23 recordings of bowel sounds from the group of children who did not receive EN. In 4 cases (17.4 %) no bowel sounds were recorded, in 16 cases (69.6 %) only isolated sounds were recorded, in 3 cases (13.0 %) isolated and grouped sounds were recorded. No prolonged bowel sounds were recorded in the group. The mean interval between sounds was 9.63±2.04 seconds (Me - 8.68 seconds). In the group of neonates receiving EN at the time of examination before feeding (49 recordings), in 11 cases (22.4 %) only is olated sounds were recorded, in 36 cases (73.5 %) isolated and grouped sounds were recorded, in 2 cases (4.1 %) sounds of all types were recorded. The mean interval between sounds was 2.10±0.27 seconds (Me - 1.55 seconds). During the post-feeding examination (47 recordings), in 14 cases (29.8 %) only isolated sounds were recorded, in 30 cases (63.8 %) isolated and grouped soundswere recorded, in 3 cases (6.4 %) sounds of all types were recorded. The mean interval between sounds was 2.93±0.42 seconds (IQR – 1.76 seconds). In neonates at 28-31 weeks gestational age who were enterally fed, the number of isolated bowel sounds detected was signifi cantly higher (compared to the group of neonates who were not fed), as was the number of grouped sounds. The interval between bowel sounds was signifi cantly longer in the group of neonates who were not fed. In neonates with PCA at 32-33 weeks, the number of isolated and grouped sounds was signifi cantly higher than in neonates who were not breastfed. In the group of infants with a PCA of 34-36 weeks, the number of isolated sounds was also signifi cantly higher. A signifi cant diff erence was found in the number of isolated sounds before and after feeding and in the duration of the interval between sounds. When the data were analyzed without regard to PCA, there was a signifi cant decrease in the number of isolated sounds after eating from 29.4±1.49 to 24.5±1.89 and an increase in the duration of the interval between sounds from 2.10±0.27 to 2.93±0.42. In the general observation group, with an increase in PCA, there was a signifi cant increase in the frequency of recording isolated sounds, changes in other indicators in our study were not signifi cant.Conclusions. Accurate assessment of bowel sounds serves as a specifi c marker of a healthy and viable bowel. In particular, an increase in the number of isolated and grouped sounds, as well as a decrease in the intervals between sounds, is noted in premature infants ready for enteral feeding, as opposed to infants with feeding intolerance. An increase in PCA is also associated with an increase in the number of isolated sounds during observation. We believe that quantitative monitoring of neonatal bowel sounds may be of clinical benefi t in preterm infants at risk for bowel dysfunction.