Neonatal sucking: effects of quantity of the response-contingent fluid upon sucking rhythm and heart rate

Comparison of physiological and behavioral responses to fresh and thawed breastmilk in premature infants--a preliminary study

BACKGROUND

Breastmilk is usually frozen for premature infants when they are unable to feed orally. However, thawed breastmilk may have altered odor and taste from its original form. Few studies have investigated whether premature infants respond differently to fresh and thawed breastmilk. The purpose of this study was to examine the physiological and behavior responses of premature infants alternately fed fresh and thawed breastmilk.

SUBJECTS AND METHODS

An experimental, crossover study using random assignment was conducted. A convenience sample of 18 premature infants less than 37 weeks gestational age at birth with the capability of oral feeding was studied. The premature infants were fed with fresh and thawed breastmilk during two consecutive meals in a random order. Infants' heart rate and oxygen saturation levels were measured baseline and during feeding, as well as observed feeding cues during the feeding period.

RESULTS

Premature infants showed significant differences in heart rate when fed thawed, as opposed to fresh, breastmilk. Premature infants demonstrated more stress cues when fed thawed compared with fresh breastmilk (p=0.007). For infants with postmenstrual ages greater than 36 weeks gestation, feeding with thawed breastmilk showed more stress cues and greater effect on heart rate activity compared with fresh breastmilk (p<0.05).

CONCLUSIONS

Older premature infants demonstrate more stress when fed with thawed breastmilk. Preterm infants should be directly breastfed or fed with nonfrozen breastmilk, when they show stress behaviors in being fed with thawed breastmilk.

Nutritive and nonnutritive sucking and the temporal organization of the suckling behavior of domestic piglets

Detailed video recordings of the suckling behavior of one piglet from each of four litters were analyzed to determine how the components of piglet suckling behavior are organized in relation to the time of milk ejection and the temporal pattern of grunting by the sow. Early in the suckling episode, most piglets massaged the udder with their snouts, and then changed gradually to sucking the teats with slow mouth movements (1-2/sec). The piglets then had a distinct phase of sucking with rapid mouth movements (4-5/sec) which began suddenly and lasted about 5 to 15 sec. The weight gains of piglets removed at different times showed that piglets consumed milk during the fast sucking but not during the preceding slow sucking, regardless of how much slow sucking had occurred. Three of the four sows showed a characteristic increase in rate of grunting about 20 to 25 sec before fast sucking began. The piglets' change from massaging to slow sucking often coincided with the increase in grunt rate, but the timing of the transition varied greatly. This suggests that the change in grunting is one but not the only cue used by the piglets to time their suckling behavior. During the slow, nonnutritive sucking, mouth movements were highly variable in duration, with occasional short bursts of rapid mouth movements. This contrasted with the more uniform duration of fast sucking movements. Evidently, in piglets, nutritive and nonnutritive sucking differ in both rate and temporal patterning.

Spontaneous non-nutritive sucking in continuously fed infants

In order to investigate the effects of a deprivation of the nutritive sucking (NS) on the activity of non-nutritive sucking (NNS), we examined 8 infants (ages 1-13 months) continuously fed by intracaval catheter. They had no NS experience at all from birth. Eight age-matched normally fed infants served as controls. The infants were examined for a full 24-h period by polygraphic recordings and behavioural observation. The amount of NNS was computed for the whole 24-h period and separately for each behavioural state (waking, quiet sleep, paradoxical sleep and ambiguous sleep). All the continuously fed infants showed a typical pattern of NNS. There were no differences in amount of NNS between continuously fed and control infants in any behavioural state. These results suggest that NS does not contribute to the long term maintenance of the NNS activity.