551 - Evaluation of olfactory stimuli on brain oxygenation of healthy newborns

Poster Number: 551
Publication Number: 551.41

Susana Rodriguez, SIBEN, CABA, Buenos Aires, Argentina; Marcelo Cardetti, Sociedad Iberoamericana de Neonatología, San Luis, San Luis, Argentina; Sergio G. Golombek, SUNY Downstate Health Sciences University, Brooklyn, NY, United States; Augusto Sola, Ibero American Society of Neonatology-, Wellington, FL, United States

Background: Neonatal near-infrared spectroscopy studies have shown changes in cerebral oxygenation of the prefrontal area in response to odor. Until now, the effect of usually used perfumes has not been explored.

Objective: To evaluate the effect of an olfactory stimulus (perfume) on brain oxygenation values in healthy term newborns, and to compare the effect according to gender and location of the newborn (NB), crib vs. skin-to-skin contact (STS).

Design/Methods:

Exploratory experimental study in healthy term newborns ≥ 6 h of life, in rooming-in, in
a calm postprandial state, without auditory or visual stimuli. Informed consent was obtained.
After inclusion, NB’s were randomly assigned to crib vs STS. The olfactory stimulus consisted of
the use of 2 swabs soaked in a perfume placed 25-50 mm in front of the nostrils for 10 seconds.
Cerebral oximetry was monitored by O3® Regional oximetry (Masimo) with neonatal sensors
located on the forehead on the left side. Values were recorded in 4 periods: 1) basal; 2) stimulus
(10 seconds); 3) immediate post-stimulus (average of the 1st min post discontinuation of the
stimulus) and 4) 2 minutes post-stimulus (average of the 2nd minute). rScO₂ variation was
considered when values changed ± 2% from baseline. Analyses was global and by gender and baby’s condition (STS vs. crib). We used ANOVA for repeated measurements, each subject being their own control and post-hoc analysis with paired t-test and Bonferroni correction.

Results:

40 NB’s were included, 50% male, birth weight 3245± 401g. The rScO₂ values were 71.7 ± 6.5% (baseline), 72 ± 6.7% (during stimulus), 72 ± 5.7% and 73 ± 5.4% (at the 1st and 2nd minute), without significant differences (p 0.19). rScO₂ was modified in 20 NBs (50%) during the olfactory stimulus (between -9 to +11%) and rScO₂ changes were observed at some point in the study (during or post-stimulus) in 30 NBs (75%), with high variability. In half rScO₂ decreased (-3 to -9%) and in the other 15 NBs it increased (+3 to +19%). The changes in rScO₂ were not related to gender (p 0.06) or STS (p 0.2).

Conclusion(s):

The olfactory stimulus with perfume affected rScO₂ in the majority of NBs, regardless of gender and STS. The effect was variable, increasing or decreasing the rScO₂ values. These results show that there is activation of olfactory pathways against the perfume,
and that these changes can be detected by rScO₂. The meaning of these individual variations is still uncertain but we speculate that this investigation may be of importance to understand the mechanisms that regulate cerebral oxygenation NB’s.