Maturation of oral feeding skills in preterm infants

Abstract

Aim: Safe and successful oral feeding requires proper maturation of sucking, swallowing and respiration. We hypothesized that oral feeding difficulties result from different temporal development of the musculatures implicated in these functions.

Methods: Sixteen medically stable preterm infants (26 to 29 weeks gestation, GA) were recruited. Specific feeding skills were monitored as indirect markers for the maturational process of oral feeding musculatures: rate of milk intake (mL/min); percent milk leakage (lip seal); sucking stage, rate (#/s) and suction/expression ratio; suction amplitude (mmHg), rate and slope (mmHg/s); sucking/swallowing ratio; percent occurrence of swallows at specific phases of respiration. Coefficients of variation (COV) were used as indices of functional stability. Infants, born at 26/27- and 28/29-week GA, were at similar postmenstrual ages (PMA) when taking 1-2 and 6-8 oral feedings per day.

Results: Over time, feeding efficiency and several skills improved, some decreased and others remained unchanged. Differences in COVs between the two GA groups demonstrated that, despite similar oral feeding outcomes, maturation levels of certain skills differed.

Conclusions: Components of sucking, swallowing, respiration and their coordinated activity matured at different times and rates. Differences in functional stability of particular outcomes confirm that maturation levels depend on infants' gestational rather than PMA.

Figures

Figure 1

Schematic representing the simultaneous pressure recordings of sucking (suction and expression components), onset of swallowing and respiration (upward deflection: inhalation) over time. Dotted lines on each tracing delineate measures of time interval (sec). Swallow–respiration interfacings were identified by the time at which onset of pharyngeal swallowing and a particular respiratory phase occurred. The example shown by the dotted line between swallow and respiration is that of a swallow occurring at the beginning of inhalation.

Figure 2

Schematic describing the various swallow–respiration interfacings. Swallowing can occur during inhalation (i), end of inhalation/start of exhalation (end i), during exhalation (e), interrupting inhalation (ii), interrupting exhalation (ie) or during deglution apnea defined as apnea ≥2 sec.