ARTIFICIAL AROUSAL IN BABIES AS STRATEGY TO RESUME PROLONGED APNEAS WITHOUT DISRUPTING SLEEP

Abstract

SIDS happens when babies are asleep and newborn babies spend 15 hours per day sleeping. In fact, the term SIDS refer to infants who die in their sleep with no evidence of accidental asphysia, inflicted injury or organic disease .This study has the objective to demonstrate that there are artificial mechanisms precise enough to induce an arousal similar to the expected naturally in current risky situations (like a prolonged apnea) in healthy babies.

Full text

SIDS happens when babies are asleep [1] and newborn babies
spend 15 hours per day sleeping. In fact, the term SIDS refer to
infants who die in their sleep with no evidence of accidental
asphysia, inflicted injury or organic disease [2]. SIDS is a
multifactorial syndrome mainly related to overheating, prolonged
apnea, gastroesophageal reflux or inadequate bedding system and
posture. According to the Triple Risk Model [3], SIDS results when
three factors simultaneously influence the infant:
· An underlying vulnerability in the infant.
· A critical developmental periodn
· An exogenous stressor, e.g. hyperthermia
PRECISE ARTIFICIAL AROUSALS IN BABIES
AS A STRATEGY TO RESUME PROLONGED
APNEAS WITHOUT DISRUPTING SLEEP
INTRODUCTION
M. Valero
M. Morell / G. Pin
T. Zamora
J. Diez
Instituto de Biomecánica de Valencia.
Unidad de Sueño Hospital Quirón Valencia.
European Sleep Care Institute (ESCI).
ASEIP, Valencia, Spain.
Authors Affiliation
In this model, such exogenous stressors are postulated to induce
asphyxia, hypercapnia and hypoxia.
A failure to arouse is also one of the causes of SIDS, if babies stop
breathing during sleep; as a defense mechanism, they usually
arouse and start breathing again. In eect, they revive themselves.
However, if the baby does not arouse in time -fail to wake up and
take a deep breath to end a prolonged apnea-, there is a second line
of defense, gasping [6]. The infant’s brain stimulates slow, deep,
labored breaths that temporarily restore his oxygen supply. If this
mechanism also fails, the infant will die from a lack of oxygen.
References
[1] T. Hoppenbrouwers and J. Hodgman, SIDS, Calabasas, CA:
Monte Nido Press (ISBN: 0-9742663-0-2), 2004.
[2] R. Byard and H. F. Krous, “Sudden Infant Death Syndrome:
Overview and Update,” Pediatric and Developmental Pathology,
no. 6, pp. 112-127, 2003.
[3] H. Kinney, H. Richerson, S. Dymecki, R. Darnall and E.
Nattie, “The Brainstem and Serotonin in the Sudden Infant
Death Syndrome,” The Annual Review of Pathology:
Mechanisms of Disease, vol. 4, pp. 517-50, 2009.
[4] J. Filiano and H. Kinney, “A perspective on
neuropathologic findings in victims of the sudden infant death
syndrome: the triple-risk model,” Biol. Neonat., vol. 65, p.
194–97, 1994.
[5] F. McNamara, F. Issa and C. Sullivan, “Arousal pattern
following central and obstructive breathing abnormalities in
infants and children,” Journal of Applied Physiology, vol. 81,
pp. 2651-2657, 1996.
[6] F. McNamara, H. Wulbrand and B. Thach, “Characteristics
of the infant arousal response,” Journal of Applied Physiology,
vol. 87, pp. 2314-2321, 1998.
The importance of arousal mechanisms related to SIDS is postulated
by several reports ([5], [6], [7], [8], [9], [10], [11]). In fact two studies
have provided evidence of decreased spontaneous arousals during
sleep in SIDS compared with control infants ([12], [13]).
This study has the objective to demonstrate that there are artificial
mechanisms precise enough to induce an arousal similar to the
expected naturally in current risky situations (like a prolonged
apnea) in healthy babies.
Figure 3. Evidence of an
arousal registered during one
of the pilot experiments. Left:
Vibratory signal registered by
the accelerometer in blue.
Alfha, beta, delta and theta
waves. Right: FFT of the
screen-shoot period. Figure 5. The system set up considered 6 vibratory motors and 1 accelerometer
to measure the stimulus.
Figure 4. Interface
programmed in Labview to
control de experiment and
capture the results.
Table 1. Design of
experiments for
trials with 36
babies (T2.6)
Table 2. Summary of the arousals resulted.
Figure 6. Left: Image of a baby sleeping in lateral position during the experiment.
Right: Temperature sensor used inside the mattress.
MATERIAL AND METHODS
The stimulus selected by the study researchers to induce an artificial
arousal was a vibratory surface. This mechanism was inspired on the
evidence that a baby nurse usually produce a positive reaction when
touching softly the baby body during a prolonged apnea. During a
pilot study with 6 babies, it was explored dierent designs to
produce the stimulus and validate the hypothesis. Results of pilot
study validated that with fullterm babies, it was possible to induce a
cortical arousal with 6 vibratory motors (figure 1, figure 2) but the
sleep stage and the posture of the baby was presented as key
factors to control the vibratory energy and don’t wake up the baby.
To control the vibratory stimulus produced by the 6 motors during
the experiment, it was designed a labview interface which was
programmed to switch on the motors by the researched producing
an intermittent and random vibration calculated automatically. The
vibration energy could also be controlled using 3 force ranges. The
interface capture simultaneously the accelerometer signal and
allows the researcher to introduce the feedback of the EEG signal
observed and described by the Neurophysiologist that took part in
the experiment.
To do the experiment, it was considered 12 baby groups according
to the criterial of 8 experts (pediatricians) that collaborated during
the study: 6 age periods and 2 gestational groups (full-term,
preterm). Table 2 presents the number of babies recluted for the
experiment. All babies were recluted by pediatricians involved in the
study and were all health and without any arousal nor respiratory
problems detected by doctors.
RESULTS
Table X presents a summary of the arousals resulted during the 28
experiments according to the sleep stage (N1, N2, N3) and the
vibratory energy (LEVEL) used each time. The experiment got 222
cortical arousals.
Finally it was done a fuzzy logic analysis to simulate graphically
an algorithm to produce the correct vibratory stimulus
according to the significant factors (Figure 8).
The ANOVA analysis detected as significant factors to produce an
arousal (Figure 7) following parameters:
· Vibratory LEVEL
· Gestational Age
· Baby sleep Posture
Figure 1. The
motor was
allocated inside a
plastic capsule
which was
inserted inside a
baby mattress.
Figure 2.
Microvibe motor
used during the
experiment.
The experiment consisted in producing dierent stimulus trying to
induce an arousal in all sleep stages (REM and NonREM: N1, N2,
N3-N4) without waking up the baby. All the experiments were done
during the early night sleep in the same hospital room by the same
research team (1 engineer and 1 neurophysiologist). Posture of the
THE FOLLOWING SIGNALS WERE INSTRUMENTED:
· EEG. 1: SaO2, 2: T2-O2, 3: Fp1-T3, 4: T3-O1, 5: Fp4-C4,
6:C4-O8, 7: Fp1-C3, (Figure 6-Left); C3-O1.
· Temperature (sensor to be added in the mattress surface)
(Figure 6 Right).
· Respiration.
· Mattress acceleration and input signal for the vibrators.
baby was selected voluntary by the baby career to do not influence
the baby current sleep habits. Only prone posture was not allowed.
Dierent analysis (ANOVA, Correlations, Fuzzy logic) were
performed to understand how factors controlled during the
experiment could influence the results.
Dierent analysis (ANOVA, Correlations, Fuzzy logic) were
performed to understand how factors controlled during the
experiment could influence the results.
The system, presented as an artificial stimulator under the baby
body, has been able to induce a cortical arousal in the 12 baby
groups included into the study. The fuzzy logic analysis indicates
that the designed system works properly only in supine posture.
This could be explained because in supine posture the baby rest
the whole shoulder over the vibratory mattress.
None of the groups gave significant results with the minimum
vibratory level selected at the experiment, future experiment
should contemplate higher vibratory levels.
Younger-full term babies needed the highest vibratory levels to
produce an arousal, maybe this evidence indicates that during
this life-period the babies sleep deeper.
The system presented in this study could be trained for each baby
to produce an arousal in case of risky situations that could be
automatically detected by a respiratory monitoring system at
home or in a hospital. If the vibratory Level is performed properly,
the baby will arouse without disrupting the sleep stage avoiding
an emergency alarm every risky situation or every false positive
signal could shoot an emergency alarm.
This study has been financed by EU FP7 under the project Baby
Care Sleep.
Project coordinator: Colchones Delax
Project Partners: Cogent, VDS, Pin Arboledas, IBV, ISRI,
Centexbel and ASEIP.
DISCUSSION
AND CONCLUSION
[7] A. Lijowska, N. Reed, B. Mertins Chiodini and B. Thach,
“Sequential arousal and airway defensive behaviour of
infants in asphixial sleep environments,” Journal of Applied
Physiology, vol. 83, pp. 219-228, 1997.
[8] M. Page and H. Jeffery, “Airway protection in sleeping
infants in response to pharyngeal fluid stimulation in the
supine position,” Pediatric Research, vol. 44, pp. 691-698,
1998.
[9] H. Wulbrand, F. McNamara and B. Thach, “Suppression
of sigma spindle EEG activity as a measure of transient
arousal following spontaneous and occlusion sighs and
startles,” Pediatric
Research, vol. 44, pp. 767-773, 1998.
[10] F. McNamara, A. Lijowska and B. Thach, “Spontaneous
arousal activity in infants during NREM and REM sleep,”
Journal of Physiology, vol. 538, no. 1, pp. 263-269, 2002.
[11] B. Galland, G. Reeves, B. Taylor and D. Bolton, “Sleep
position, autonomic function and arousal”, Archives of
Diseases of Children, Fetal Neonatal Edition, vol. 78, pp.
189-194, 1998.
[12] A. Kahn, J. Groswasser, E. Rebuffat, M. Sottiaux, D.
Blum, M. Foerster, P. Franco, A. Bochner, M. Alexander, A.
Bachy, P. Richard, M. Verghote, D. Le Polain and J.
Wayenberg, “Sleep and cardiorespiratory characteristics of
infant victims of sudden infant death: a prospective
casecontrol study,” Sleep, vol. 15, pp. 287-292, 1992.
[13] V. Schechtmann, R. Harper, A. Wilson and D. Southall,
“Sleep state organization in normal infants and victims of
sudden infant death syndrome,” Pediatrics, vol. 89, pp.
865-870, 1992.
Tomás Zamora
innovation@escinstitute.com
(+34) 670 372 937
www.escinstitute.com
Figure 8. Decision tree resulted at the fuzzy logic analysis for training the
system according to main significant factors resulted in the experiment.
Figure 7. Influence of the main factors
(baby posture, vibration level and
gestational age) over the AROUSAL
produced by the experiment. Vibration
level 3, Preterm babies and supine
position favors a higher arousal
registration..