Technological solutions and main indices for the assessment of newborns' nutritive sucking: a review

Abstract

Nutritive Sucking (NS) is a highly organized process that is essential for infants' feeding during the first six months of their life. It requires the complex coordination of sucking, swallowing and breathing. The infant's inability to perform a safe and successful oral feeding can be an early detector of immaturity of the Central Nervous System (CNS). Even though the importance of early sucking measures has been confirmed over the years, the need for standardized instrumental assessment tools still exists. Clinicians would benefit from specifically designed devices to assess oral feeding ability in their routine clinical monitoring and decision-making process. This work is a review of the main instrumental solutions developed to assess an infant's NS behavior, with a detailed survey of the main quantities and indices measured and/or estimated to characterize sucking behavior skills and their development. The adopted sensing measuring systems will be described, and their main advantages and weaknesses will be discussed, taking into account their application to clinical practice, or to at-home monitoring as post-discharge assessment tools. Finally, the study will highlight the most suitable sensing solutions and give some prompts for further research.

Figure 1.

(a) IP of a 1-week healthy subject during bottle feeding; (b) Power Spectral Density (PSD) of intraoral pressure during NS (adapted from [23] with permission).

Figure 2.

Schematic diagrams of a nipple designed for nutrient delivery and IP monitoring: (a) PT connected to an end of a catheter whose other end is connected to the oral cavity; (b) PT inserted in the catheter and directly flushing in the oral cavity.

Figure 3.

Schematic diagrams of feeding apparatuses designed for nutrient delivery and IP monitoring: (a–b) configurations including a capillary tube, where a PT measures pressure changes between the nipple and the capillary tube (a), or in the oral cavity through a second catheter inserted into the nipple (b); (c) a PT measures the pressure changes in a chamber directly communicating with the oral cavity, and the nutrient is delivered from an open reservoir through a catheter into the mouth.

Figure 4.

(a) Portable sensing feeding apparatus for IP monitoring: the nutrient is released into the infant's mouth through a tube connected to a common nutrient reservoir. The tube presents an orifice restriction at the beginning and a PT for IP measurement before the nipple; (b) Equivalent electronic circuit of the apparatus.

Figure 5.

Sensing solutions for EP measurement: (a) a PT measures EP by means of the compression of a silicone tube inserted into the catheter connected to the transducer; (b) a PT is connected via a catheter to the lumen of the nipple (continuously filled with liquid); a one-way valve between the nutrient chamber and the nipple is applied.

Figure 6.

Sensing solutions for the measurement of the net pressure forcing the nutrient out of the nipple chamber. Two PTs are adopted to measure intranipple and intraoral pressure, and calculate the pressure gradient causing the nutrient to flow out.

Figure 7.

Position of the marker on the throat region, for DLT method application, is determined by first locating three facial markers: the external eye angle (A), the tip of the jaw (B) and the throat region (C).

Figure 8.

Different devices used for swallowing monitoring: PT connected to a transnasal catheter; pressure drum applied on the hyoid bone; microphone applied on the throat.

Figure 9.

Devices used for breathing monitoring. (a) Nasal thermistor or thermocouple applied below the nostrils for nasal airflow measurement; pressure drum or strain gauge band on the chest for respiratory movements measurement; (b) Rigid tool applied into the nostrils: the thermistor and the PT are used respectively to assess air flow and its versus.