The Car Seat Tolerance Screen (CSTS) is a standard medical observation performed on certain newborns before they are discharged from the hospital. The procedure determines if an infant can safely tolerate the semi-upright position required for travel in a motor vehicle. This screening focuses on the baby’s physiological response to the car seat angle, monitoring for any compromise in breathing, heart rate, or oxygen levels due to the positioning. The goal is to ensure the infant is medically ready for the transition home.
Who Undergoes the Car Seat Tolerance Screening
The American Academy of Pediatrics (AAP) recommends this screening primarily for infants considered to be at a higher risk for cardiorespiratory instability. The most common group requiring the CSTS are babies born prematurely, specifically those delivered before 37 weeks gestational age. Infants with a low birth weight, often defined as less than about 5 pounds, are also frequently screened.
These infants are vulnerable because their respiratory and neurological systems are still immature. Underdeveloped muscular tone and respiratory control can make it challenging for them to maintain a clear airway when positioned in a semi-reclined seat. Other conditions necessitating the test include a history of apnea, bradycardia, respiratory distress, or certain congenital heart or airway anomalies. The CSTS is typically performed within 12 to 24 hours of the expected discharge date.
Physiological Criteria for Failing the Test
A baby fails the CSTS when specific changes occur in their vital signs while observed in the car seat. The primary metrics monitored are the infant’s heart rate, oxygen saturation levels, and breathing pattern. These measurements are continuously tracked using a cardiorespiratory monitor and a pulse oximeter during the observation period, which typically lasts 90 to 120 minutes.
Desaturation
One common failure criterion is a significant drop in blood oxygen saturation (\(\text{SpO}_2\)), known as desaturation. This is defined as the level falling below 90 percent for a duration of 10 seconds or longer. This drop is a direct indicator that the infant is not receiving or processing enough oxygen in the semi-upright position.
Bradycardia
Bradycardia is a significant slowing of the heart rate. The threshold is typically a heart rate dropping below 80 to 100 beats per minute for a sustained period, often defined as 10 seconds or more. Bradycardia frequently occurs as a response to low oxygen levels caused by desaturation or a pause in breathing.
Apnea
Apnea is defined as a pause in breathing. A failure is recorded if the infant stops breathing for 15 to 20 seconds or longer. A shorter pause in breathing accompanied by a drop in heart rate or oxygen saturation also qualifies as a failure. The semi-reclined angle can cause the infant’s chin to fall toward their chest, potentially compressing the airway.
Interventions and Next Steps After a Failure
When an infant fails the Car Seat Tolerance Screen, they are immediately removed from the car seat and provided medical intervention, which may include repositioning, stimulation, or administering oxygen. The healthcare team then communicates the results to the ordering physician. A failure indicates the baby is not yet safe for discharge in a standard car seat, and the discharge process is paused.
Adjusting the Car Seat Setup
A common intervention is adjusting the car seat setup to achieve a better, open-airway position. This often involves using approved support devices, such as tightly rolled blankets or towels, placed alongside the infant’s head and torso to maintain proper alignment. It is crucial that these supports are only placed next to the baby and never under them or between the baby and the harness straps, as this interferes with the seat’s crash protection features.
If repositioning is successful, the infant undergoes a retest after a recovery period that can last several hours or even a day. If the infant continues to fail, even with approved supports, the medical team may recommend an alternative device. This alternative is typically a specialized car bed, which allows the baby to travel in a completely flat, supine position, eliminating the positional risk associated with the semi-upright seat.
Continued Care and Monitoring
In some cases, the physician may recommend the infant remain in the hospital for a few more days, allowing for further maturation of the respiratory control system before another retest is attempted. Following a failed screen, some infants may be discharged with a home cardiorespiratory monitor. This device tracks their breathing and heart rate, providing an added layer of safety until the infant demonstrates full physiological stability.