Non-nutritive sucking habits in sleeping infants.

BACKGROUND: Pacifier use has been postulated to decrease the risk of sudden infant death syndrome (SIDS). The responsible mechanisms are, however, unclear. OBJECTIVES: Since little is known about the non-nutritive sucking (NNS) habits of infants during sleep, we investigated NNS patterns and changes of physiological parameters during NNS in sleeping infants. METHODS: Polygraphic recordings were performed in 12 infants with a median age of 55 days (range 7-82) who regularly used a pacifier during sleep. Episodes of active suckling (bursts) and quiescent periods were differentiated by video observations. We evaluated the time of suckling in relation to the total time of pacifier use, the median number of bursts per min, the median duration of single bursts and the median interval between 2 sequent bursts. In 48 randomly selected bursts, we additionally analyzed changes in heart rate, respiratory frequency and oxygen saturation compared to the 10-second period preceding the burst. RESULTS: Median sleep time with a pacifier held in mouth was 31.3 min (13.0-117.6), of which 15.5% (6.4-36.7%) was spent with active suckling. The median number of bursts per min was 2.2 (1.2-4.5). The median duration of a burst was 3 s (1-22) and the median interval between 2 bursts was 10 s (1-1,434). Heart rate, respiratory frequency and oxygen saturation did not change significantly during suckling bursts. CONCLUSIONS: This pilot study presents important data for sucking habits in pacifier users which may provide a basis for further investigations concerning the efficacy of pacifiers in SIDS prophylaxis.

Pacifier use does not alter the frequency or duration of spontaneous arousals in sleeping infants.

OBJECTIVE: It has been reported that pacifiers might reduce the risk of SIDS by favouring infants' arousability from sleep. We evaluated the influence of a pacifier on the frequency and duration of spontaneous arousals in healthy infants. METHODS: Polygraphic recordings were performed in 14 infants with an age of 51.7+/-19.9 days (means+/-SD) who regularly used a pacifier during sleep. Cortical and subcortical arousals were scored according to the recommendations of the "International Paediatric Work Group on Arousals." The number of arousals per 10-min-period and the duration of arousals were determined for periods of pacifier use as well as for periods after pacifier dislodgement and were compared with the data of 10 control infants (age 49.8+/-16.5 days) who never used a pacifier. RESULTS: Altogether, 211 arousals in pacifier users and 225 arousals in non-users were scored. In pacifier users, 2.0+/-1.6 arousals per 10-min-period with a duration of 12.2+/-3.0 s occurred during pacifier use, and 1.7+/-1.6 arousals per 10-min-period with a duration of 12.2+/-3.1s occurred during periods without pacifier. In pacifier non-users, 2.3+/-1.2 arousals per 10-min-period (duration 13.9+/-2.9s) were scored. The results did not show a significant difference concerning frequency and duration of spontaneous arousals between pacifier users and non-users. CONCLUSIONS: Our findings suggest that factors other than arousal mechanisms might be responsible for the efficacy of pacifiers in SIDS prophylaxis.

Unchanged heart rate-respiratory frequency ratio in preterm infants during spontaneous arousals.

AIM: To find out whether a correlation of heart rate (HR) and respiratory frequency (RF) defined as HR-RF-ratio (HRR) may be helpful to identify arousals in term and preterm infants. METHODS: Polygraphic recordings were performed in 25 term infants (gestational age 40.1 +/- 1.1 weeks) and 25 preterm infants (gestational age 31.1 +/- 1.3 weeks) during undisturbed daytime sleep. Arousals were scored as suggested by the 'International Paediatric Work Group on Arousals' and divided into cortical arousals and subcortical arousals. HRR was defined as HR over RF. Arousals were compared to a 30-sec period preceding an arousals. RESULTS: Two hundred arousals were scored (100 cortical arousals and 100 subcortical arousals). HRR increased during arousals in term infants (p < 0.001). This was true for cortical arousals (p < 0.001) and subcortical arousals (p < 0.05) of term infants. In contrast, in preterm infants HRR remained unchanged during cortical arousals and subcortical arousals. CONCLUSION: An increase of HRR during arousals is a simple parameter to identify arousals in term infants, but not in preterm infants suggesting that an unchanged HRR might be an indicator of an immature arousal response.

Comparison of heart rate responses during cortical and subcortical arousals in term and preterm infants.

The aim of this study was to determine whether prematurity affects heart rate responses during spontaneous arousals. Polygraphic recordings were performed during undisturbed daytime naps in 35 preterm infants (gestational age at birth 32+/-2 weeks) and 35 term infants. Arousals were scored according to the recommendations of the International Paediatric Work Group on Arousals and categorized either as cortical arousals (CA) or subcortical arousals (SCA). Heart rate (HR) and respiratory frequency (RF) were measured during arousal and during the 10-s and 30-s period before and after arousal. Changes in HR and RF were expressed as the percentage of modification normalized for the 30-s period preceding arousal. Altogether, 122 arousals in preterm infants (66 CA, 56 SCA) and 105 arousals in term infants (57 CA, 48 SCA) were scored. Mean duration of the arousal period was 9+/-4 s and 8+/-3 s, respectively. In term infants, a significant increase in HR during arousal could be shown (11.3+/-8.2%; p<0.001), whereas this increase was significantly greater during CA compared to SCA (13.7+/-6.2% versus 8.4+/-9.4%; p<0.001). In contrast, HR decreased during arousal in preterm neonates (-3.9+/-19.3%; p<0.05). These findings suggest that cardiovascular control seems to be maturationally delayed in preterm infants, which may contribute to their increased risk for Sudden Infant Death Syndrome (SIDS).