Covidien WarmTouch, Service Manual

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Troubleshooting
6-2 Service Manual
6.3
Principles of Operation
6.3.1
Overview
The Covidien WarmTouch™ Convective Warming System provides clinicians
with a means to supply warmed or room temperature air to the skin surface of
patients to achieve and maintain normothermia. The system consists of the
Covidien WarmTouch™ Convective Warming Unit and specially designed
blankets to distribute the air.
The warming unit is powered from wall outlet AC power through an internal
power supply that maintains a consistent output across a range of input volt-
ages and frequencies. Users interact with the unit via a set of hardware keys
arranged around a software-controlled Graphical User Interface (GUI).
The warming unit produces air output by drawing room air through a High
Efficiency Particulate Air (HEPA) filter, across a heating element, and into an
electrically-operated fan. The fan outputs the air across a control thermistor at
the base of the hose. The temperature of the air is monitored by a hardware
circuit under software control that provides power to the heating element to
regulate the temperature for the heated air settings. The heated air is deliv-
ered to the output hose where the nozzle connects distally to the blanket,
resulting in air delivery to the patient.
The delivered air temperature is constantly monitored by the warming unit’s
microprocessors. If the temperature does not stay within specification, the unit
shuts down the heating element and the fan. A safety thermostat provides
additional protection by shutting down the heating element and fan if the
heated air temperature exceeds its operating limit.