Quantitative Assessment of Nutritive Sucking Patterns in Preterm Infants (P11-095-19)

Objectives Mastery of oral feeding independent of supplementary feeding tubes is crucial for safe discharge of very preterm infants (≤ 32 weeks of gestation). Qualitative assessments of suck-swallow-breathe coordination can be subjective and result in prolonged hospitalizations and delay discharges. Quantitative assessment of sucking activity during feeding (i.e., nutritive sucking) could improve determination of readiness for progression to independent oral feeding and facilitate discharge planning. To quantitively assess nutritive sucking patterns using an instrumented feeding bottle. Methods Preterm infants ≤ 32 weeks of gestation who attained independent oral feeding were prospectively evaluated after written informed consent was obtained. Infants with congenital anomalies and infants with major comorbidities were excluded. Nutritive sucking was assessed for a minimum of one feeding session in each participant by instrumenting a commercially available feeding bottle with a detachable pressure sensor configured to detect changes in the bottle enclosure. Speech pathologists administered the feeding using a standardized technique with infants under continuous cardiorespiratory monitoring. Type of feed, volume, and schedule was maintained consistently in accordance with each participant's defined regimen during his/her hospitalization. Results We analyzed 63 feeding sessions from 33 preterm infants. Mean birthweight of study participants was 1160 g (SD: 455) and median gestational age was 28 weeks (IQR: 27 – 31). Nutritive sucking patterns were assessed at term equivalent age (median corrected gestational age: 37 weeks; IQR: 35 – 39). During each feeding session, the median suck count was 784 (IQR: 550 – 1053), the median sucking rate was 0.6/s (IQR: 0.5 -0.9), the median number of brief feeding interruptions was 10 (IQR: 6–15), and the median value of sucking bursts was 52 (41-65) [Image]. Maximum suck strength strongly correlated with suck count (r = 0.68). A positive association between suck count and sucking bursts was found in unadjusted regression models (R2 = 0.35; P < 0.0001) and models adjusted for gestational age at birth, birthweight, feeding volume, transient events during feeding, and postnatal age (R2 = 0.50; P < 0.0001). Conclusions In stable very preterm infants, nutritive sucking patterns can be quantified by instrumentation of commercially available feeding bottles. Further analyses of sucking burst patterns may improve determination of readiness for progression to independent oral feeding in preterm infants. Funding Sources None. Supporting Tables, Images and/or Graphs

Shift of ionization equilibrium in spatially confined laser induced plasma

Spatial confinement of laser-induced plasma leads to shift of ionization equilibrium and can improve determination of elements by their resonant atomic lines.

Maximum-likelihood determination of anomalous substructures

A fast Fourier transform (FFT) method is described for determining the substructure of anomalously scattering atoms in macromolecular crystals that allows successful structure determination by X-ray single-wavelength anomalous diffraction (SAD). This method is based on the maximum-likelihood SAD phasing function, which accounts for measurement errors and for correlations between the observed and calculated Bijvoet mates. Proof of principle is shown that this method can improve determination of the anomalously scattering substructure in challenging cases where the anomalous scattering from the substructure is weak but the substructure also constitutes a significant fraction of the real scattering. The method is deterministic and can be fast compared with existing multi-trial dual-space methods for SAD substructure determination.