Incubators

Incubators

1. Incubators Compiled and Presented by: Dr. Judith Justin M.Tech ., Ph.D., Prof. & Head, Department of Biomedical Instrumentation Engineering Faculty of Engineering Avinashilingam University Coimbatore - 641 108

2. Ohmeda Giraffe Omnibed

3. Introduction Premature newborns require their body temperature to be elevated & controlled within a specific range When kept in a temperature controlled chamber, the oxygen requirements are minimized Premature newborns are more susceptible for developing respiratory problems, because their lungs are unable to supply enough oxygen By minimizing oxygen demands for maintaining temperature, more oxygen is available for growth Such controlled temperature environments are maintained in infant incubators.

4. Infant Incubator Temperature controlled air is passed through a chamber in which baby is located to maintain it at a set temperature Temperature is maintained by use of a proportional control system. Temperature in a air-supply line varies a thermistor resistance that is compared with a fixed resistance which corresponds to the set temperature If the temperature of air entering the infants chamber is lower than the set temperature, power is applied to the heater (to switch ‘ON’ and) to correct the difference In the proportional controller system, the amount of power applied to the heater is proportional to the difference between actual air temperature and the set point. This means that the amount of power decreases as temperature approaches the set point, an important feature in effecting more precise control and minimizing overshoot of the set point

5. Comparator Gate pulse generator Thermistor Bridge Set-point resistor 1-Hz sawtooth generator Silicon- controlled switch Heater Amplifier ν 1 ν 2 ν 3 ν 4 ν 5 Power line Block Diagram The control system shown in fig. uses thermistor in a bridge circuit, with the set point resistance as another arm of the bridge. The bridge output is amplified, giving the voltage V1 at the output, which is proportional to the difference in temperature between thermistor and the set point

6. Some incubators measure skin temperature of infant over the liver, instead of air temperature in the chamber. In such cases, the thermistor is strapped to the body of the infant Incubators have an alarm to alert clinical staff when there is overheating Buzzer is connected in series with a switch which is activated by a bimetallic strip In some cases when infants skin surface has to be exposed to carry special procedures/attach diagnostic or therapeutic devices then we use heated air and convection In such cases radiant warmers are used

7. Radiant warmer Infant is placed on a mattress under a radiant heating element. Low walls surround the mattress so that the infant does not fall off. In other incubators, the infant must be accessed through arm ports The radiant warmer consists of a heating element such as a coil of high-resistivity wire A heat reflector above this wire helps to focus the heat energy on the mattress. The current through the heater element is controlled and overheating is avoided. Proportional control is used to achieve this. A thermistor is placed on the exposed skin or abdomen of the infant to measure the skin surface temperature. This thermistor could get heated by the radiant source giving erroneous reading. It is attached to the infant through a special pad that consists of a foam pad with a shiny metallized surface that reflects thermal radiation.

8. Apnea monitor Sometimes infants develop respiratory distress or anomalies. They can stop breathing An alarm is sounded when respiratory activity ceases for periods greater than 15 to 30 seconds.

9. Any Queries???