Sudden Infant Death Syndrom (SIDS)

SIDS accounts for 500 deaths annually in Germany (4500 in the U.S, CDC 2006). It is still not clear, what causes SIDS, although a number of risk conditions are identified. One approach to prevent SIDS is the application of monitor devices to measure and analyze body parameters. Up to now, these devices are compromises between effort and indications. For a certain set of newborns at great risk (due to multiple medical reasons) rather sophisticated monitors are available at insurance cost. However, for the average infant no feasible commercially available solutions exist, that is so simple as sensor embedded textiles are.

State of the art in infant monitoring

 Physiological parameters to be monitored

To monitor newborn and small children, the following methods have been found to be useful (cite):

 Commercially available devices

A number of devices is available for home use, either prescriptive or for over the counter the use. Generally, the price is an important issue for those devices, since these devices are used at home in a familial environment; cost is an important criteria; each patient’s family keeps the monitor during an average of 4 month at home (cite). Some of the applied sensor tech-nologies are also applied for other sleeping monitor solutions, such as apnoea control for adults.

Mattress sensors

Mattress sensors consist of sensor pads, that are positioned under the bed’s mattress. The sen-sor detects small movements of an infant’s chest. A processor signals, when this movement can not be detected anymore. The devices are mostly passive (Figure 1a and b).

Integrated devices

Another type of sensors are integrated devices. Typically, they are attached to the baby during sleeping and resting periods. This devices are relatively small and weigh around 30 gramm (Figure 1c).

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Figure 1: A sensor pad is placed under the matress and a control unit attached to the bed (a © Jablotron Ltd. b © Safety 1st) c) Buzz Baby Breathing Monitor (© Baby2Bed.com)

 Research and early stages

A number of different types of project were identified (seeFigure 2).

• Mamagoose Pyjamas (by belgian company Verhaerd, www.verhaert.com) applies a system of respiration (2 capacitive elongation sensors, Patented) and Heart rate (3 electrodes measuring the potential over the heart) sensors. The device connects to an electronic box and can be read out by a PC software (Figure 2a). It seems, that the de-vice is somehow difficult to use and the cable connector between the infant and the electronics is not suitable. Cooperation with in co-operation with University of Brus-sels, Biomedical Physics Lab (Prof. Dr. M. Paiva).

• Sensatex (www.sensatex.com) describes a new device based on light, breathable, cot-ton fabric, that has fully integrated conductive fibers to measure analog physiological signals and transmit them to a small personal controller. The controller digitizes the data signals and wirelessly transmits them to a remote computer, that calculates the re-sults. The system uses wireless communication systems based ZigBee™ standard (Figure 2b). Early research for the SmartShirt System was funded by the DARPA. Sensatex claims to hold six licensed U.S. patents on conductive fiber usage. Links ex-ist to Georgia Tech.

• The german ITV Institute of Textile Technology and Process Engineering in Denken-dorf (www.itv-denkendorf.de) promotes a device, that monitors heart beat rate, breath-ing, body temperature and body humidity with elastic sensors (no further specifica-tion). The system is being currently in clinical trial at the University clinic of Tuebin-gen. The system has a cable connection between the sensor and the control unit (Figure 2c).

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Figure 2: The Mamagooese Pyjama, (© Verhaerdt Design) b) An experimental study for an e-textile shirt from Sensatex Inc. c) Prototype of a monitor device (© ITV Institute of Textile Tech-nology and Process Engineering Denkendorf)

Requirements for infant monitors

The selection of a device is based on a compromise between monitoring safety and user friendliness (especially in home care). User friendliness is strongly connected to size and mass of the device, power autonomy and the rate of false alarms. Another strong argument is the time and the effort to set up the system: possibly attach sensors, connect cables and start communications. Typically, precise and reliable sensing requires effort. Reliable sensors are difficult to set up, where simple monitor mechanisms are not reliable enough for the purpose.

The rate of false alarms (Alarm triggered without live threatening situation) should be kept small to avoid annoyed parents and the turn off of the device. Highest available safety with low number of false alarms is a combination of Heart-Breathing-Monitoring (Joch H., 2006). Here different types of devices have been pointed out, using different sensor technologies. Important for the analysis of live threatening situations is the possibility to track all sensed parameters to perform an analysis after a situation.

From the large experimental and clinical trials performed on this subject during the last 10 years, the main criteria to be taken in account for the evaluation of a new monitor are (cite):