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The infant car restraint devices are a critical part of infant safety during transportation. The crash tolerance and the critical safety features of each seat are well established. Infant transportation may be via a car seat or car bed. The effect of the sitting position on the airway is a concern in an infant with poor head control. Because of this concern, car seat tests during which oxygen saturation is measured, are performed on many low birth weight infants before discharge from the nursery. Indeed, a number of deaths have occurred in car seats probably related to airway obstruction. The relative effects of position on the ventilation need to be established.
We propose to identify the relative changes in ventilation that are induced by position change during sleep. We will collect a broad array of high quality data that will identify these changes, and the most likely cause. Specifically, we will we screen 200 infants, with each infant assigned to the supine position, the car bed and the car seat. The order of these positions will be randomly assigned. Following data will be collected:
Full description
BACKGROUND AND RATIONALE
The safe transportation of infants has formed a critical part of public health policy for many years. Clearly crash tolerance of the seat, the ease of installation, the position of the seat and the relative position to airbags has been the focus of intensive research. However as with all safety devices, there are some limitations. Respiratory instability is a potential concern due to the upright position in the car seat. This is particularly true in the premature newborn and has resulted in the recommendation to perform car safety seat testing before discharge from hospital for these infants.
Recently there have also been concerns raised about term infants. Merchant et al showed that mean oxygen saturations declined in both term and premature infants reaching a nadir of 95% after about 70 minutes of placement in a car safety seat with 8% noted to have an SaO2 of less than 90% for more than 20 minutes. Also, in an earlier study by Bass and Mehta, selected high risk full term infants were found to have increased risk of developing hypoxia.
It has been generally accepted that the potential for adverse effects from these hypoxic events are substantially offset by the crash protection afforded by these devices. Unfortunately, the portability of car seats and contemporary busy lifestyles are resulting in infants spending extended periods of time in the car seat for reasons other than transport. Callahan et al found in 187 infants that 94% spent greater than 30 minutes in seating devices including car seats each day. The mean time spent in seating devices was 5.7+/- 3.5 hours and ranged from 0 to 16 hours. Prolonged use of car seats in infants too young to sit unsupported may also potentially result in prolonged periods of oxygen desaturation.
A recent comprehensive review of peer reviewed published evidence noted that hypoxia has frequently been associated with significant defects in cognition. In some studies changes in cognitive function were seen with even mild levels of oxygen desaturation. Such changes were observed in all groups except premature babies. The young child may be relative resistant, as their physiology is adapted for the relatively hypoxic intrauterine environment. However a recent study also suggests that premature infants may also have problems. Thus a cautious approach has been adopted where children who fail to maintain adequate oxygen saturation while placed in the car seat are discharged in a car bed.
The cause of the hypoxia while placed in the car safety seat is most likely attributable to the relative vulnerability of the airway in the premature and term infant. The cause of the airway narrowing is slouching of the head forward while asleep in car seats which results in closure of the mouth, the pressing of the tongue against the posterior pharyngeal wall and the flexion of the airway. The shape of the newborn head with a prominent occiput and the reduced muscle tone encourages head slouching. A recent pilot study suggested that the placement of an insert which accommodated the occiput thus reducing the tendency towards flexion improved airway size and reduced the frequency of episodes of oxygen desaturation. Thus the flexion position, which is unique to the car seat, may have important implications for the airway of the newborn.
The American Academy of Pediatrics (AAP) currently recommends that infants with documented oxygen desaturation in a car seat should be transported in a car bed. Car beds should overcome the position dependent airway instability. However gastro-esophageal reflux may also occur in the flat position and this could potentially result in significant apnea. The purpose of this study was to define if the term infant is at increased risk of apnea and oxygen desaturation while positioned in a semi-reclined car safety seat when compared to positioning in a car bed.
METHODS
Overview Phase I Identify normal healthy newborns (200 newborns) Phase II Explain to the family the risk benefit of the study Obtain informed consent Review to see if the baby conforms to inclusion criteria Review to see if the baby does not meet exclusion criteria Randomization to supine (car bed) or sitting position (car seat) as the 1st position Phase III Physiological testing to include oxygen saturation, heart rate, respiratory plethysmography to monitor chest wall movement.
Phase IV Data for blinded and independent review
Over a period of one year, we propose to study 200 patients. Each infant will be studied in the supine position (30 minutes), car bed (60 minutes) and car seat (60 minutes). The order of positions will be randomly assigned. This size should be adequate to identify significant differences.
Inclusion Criteria
Exclusion Criteria
ORGANIZATION
DATA At the time of inclusion, we will collect basic perinatal data, including pregnancy complications, descriptors of labor and delivery, use of medications in the perinatal period (drugs, cigarettes, alcohol and caffeine). We will obtain basic information concerning the infant (i.e. date of birth, sex, and race) as well as birth weight, length, head circumference and Apgar scores.
Data Collection:
Each infant will be assigned a study number and all data will be labeled with this number. Each infant will have 4 leads place for cardio-respiratory monitoring. Oxygen saturation will be measured on the left hand. The study will be performed following feeding and a diaper change. The child will be placed in the designated position as determined by study randomization. The control position will be established by placing the infant face up in a standard hospital crib. The supine position will be established by placing the infant face up in an Aprica Car Bed. The seated position will be established using a standard car seat that results in 45 degree angle relative to the horizontal.
Early intervention or termination of the study:
The study nurse will be available at all times during the study. Dr. Lilijana Kornhauser-Cerar, Dr. Irena Štucin Gantar and Prof. David Neubauer or their designated substitutes will be available for consultation via cellular phone during the study.
If there is significant desaturation to 85% for longer than 10 seconds, the child shall be stimulated. If there is persistent desaturation, oxygen will be added. If there is still persistent desaturation, the study will be terminated.
Procedures:
DATA ANALYSIS AT IBMI
LIMITATIONS
PUBLICATION Drs. Kornhauser-Cerar, Štucin - Gantar, Neubauer and Kinane will be responsible for the publication of the results. All results will be submitted to a peer review journal for consideration.
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Exclusion criteria
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Central trial contact
Lilijana Kornhauser Cerar, MD; David Neubauer, MD
Data sourced from clinicaltrials.gov
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