Fetal swallowing: correlation of electromyography and esophageal fluid flow

Abstract

Patterns of fetal drinking behavior were quantified in five singleton fetuses (128 +/- 1 days gestation) by computer analysis of laryngeal-esophageal electromyography (EMG) and thoracic esophageal fluid flow. Esophageal flow was noted to be bidirectional with an average antegrade flow-to-retrograde flow ratio of 4.4 +/- 1.5. Retrograde esophageal flow coincided with diaphragmatic contractions, suggesting that inspiratory gastroesophageal pressure gradients may be operative. The regurgitated fluid was returned to the fetal rumen by thoracic esophageal contractions. Significant net fluid intake was noted during periods of primarily unidirectional antegrade esophageal flow. Fetuses swallowed an average of 35 +/- 9 ml/h during the 12-h study, extrapolating to an average daily volume of 840 +/- 224 ml. An EMG "propagated swallow" representing coordinated contractions of the thyrohyoid, nuchal esophagus, and thoracic esophagus averaged 43 +/- 3 swallows/h and was highly correlated with net esophageal flow. Nearly 60% of the total fluid intake occurred during "bouts" of propagated swallows, which represented only 8% of the study period. Bouts averaged 11.7 +/- 0.4 propagated swallows, lasted 2.1 +/- 0.2 min, and occurred every 27.6 +/- 1.7 min. Although EMG swallowing activity was similar, there were significant differences among fetuses in net esophageal fluid flow and volume per propagated swallow. We speculate that fetal fluid intake is dependent on the availability and physical properties of the swallowed fluid, whereas swallowing activity is primarily related to cortical maturation and thirst stimulation.

Plasma Osmolality Dipsogenic Thresholds and c-fos Expression in the Near-Term Ovine Fetus

“…EMG signals were processed as previously described (17). An EMG-propagated swallow, representing a coordinated laryngeal-esophageal contraction, was defined by a time sequence of integrated EMG signals from the thyrohyoid muscle to the upper and lower nuchal esophagus (17).…”

Neuronal NO modulates spontaneous and ANG II-stimulated fetal swallowing behavior in the near-term ovine fetus

“…were placed in the fetal femoral vein and artery and threaded to the inferior vena cava and abdominal aorta, respectively. Surgical placement of bipolar electromyography (EMG) electrodes (thyrohyoid muscle, upper and lower nuchal esophagus) for determination of swallowing activity was performed as previously described (36). Electrodes were also implanted on the parietal dura through two drilled burr holes (5 mm above the bregma and 10 mm from each side of the sagittal suture) for the determination of fetal electrocortical activity (ECoG).…”

“…amniotic fluid; angiotensin II THIRST AND APPETITE-MEDIATED ingestive behavior develop and are likely imprinted in utero, thus preparing for newborn and adult ingestive behavior. Fetal swallowing activity is markedly different from that of the adult, as basal fetal swallowing occurs at a markedly (6-fold) higher rate compared with basal adult drinking activity after body weight differences are adjusted for (35). This high rate of basal fetal swallowing is critical for the regulation of amniotic fluid volume (30) and the development of the fetal gastrointestinal tract.…”

Enhancing effects of flavored nutritive stimuli on cortical swallowing network activity

“…Deglutition, the primary ingestive behavior that develops in utero in mammalian species (42), contributes to several critical fetal developmental processes (39). The physical act of swallowing requires extensive sensory/motor coordination of oral, pharyngeal, laryngeal, esophageal, and diaphragmatic muscles (1,2) that are primarily mediated by the "swallowing center" of the brain stem (19,20).…”