Philips 862478, 862474 manual Nbp, Temperature

Theory of Operation and System Architecture

NBP	The NBP processing uses an oscillometric technique to provide needed measurements at
Processing	selected intervals. This technique uses an inflatable sphygmomanometer cuff similar to those
	used by clinicians in routine measurements.
	A motorized pump inflates the cuff to approximately 180 mmHg initially, at which point the
	pressure effectively stops the flow of blood. Then, under monitor control, the pressure in the
	cuff is gradually reduced, while a pressure transducer detects the air pressure and transmits
	the parameter signal to the NBP input circuitry.
	As the pressure is reduced, blood flows in the previously occluded artery, and changes the
	measurements made by the transducer. The point at which oscillation increases sharply is
	defined as systolic pressure. As the cuff continues to deflate, oscillation amplitude increases
	to a maximum, and then decreases. The peak oscillation amplitude is defined as the mean
	arterial pressure. The point at which the system detects a rapid decrease in oscillation is
	defined as the diastolic pressure.
SpO2	Measurement of oxygen saturation in the blood uses a specrophotometry technique. It is based
Processing	on the facts that oxyhemoglobin and deoxyhemoglobin differ in their absorbtion of red and
	infrared light, and that the volume of arterial blood in tissue changes during the pulse.
	Using these facts, a pulse oximeter passes red and infrared light into an arteriolar bed and
	measures changes in light absorption during the pulsatile cycle. The light sources are red and
	infrared light emitting diodes (LEDs), while the detection is accomplished by a photo diode.
	To identify the oxygen saturation of arterial hemoglobin, the monitor uses the pulsatile nature
	of arterial flow. During systole, a new pulse of arterial blood enters the vacular bed, and both
	blood volume and light absorption increase. During diastole, blood volume and light
	absorption reach their lowest point. The measurement is based upon the difference between
	maximum and minimum absorption, focusing on the pulsatile arterial blood.
	In addition to the oximetry function, the input signals may be used to calculate heart rate.
CO2	The Microstream CO2 board consists of an 80C552 Controller, the memory system (Flash
Processing	ROM, RAM, PLA, etc.), the Flow system (FilterLine recognition system, Inlet, solenoid
	valve), Measurement Cell (Exciter, IR Source, Detectors and Temp Sensor) and an analog
	section with ADC.
	The gas inlet allows the connection of Microstream FilterLines. The FilterLines are detected
	by the Optical Code Recognition.
Temperature	Measurement of patient temperature is accomplished by processing the signal from a probe
Processing	containing a resistor whose impedance is temperature dependent. The class of such
	components is called thermistor.
	The C3 is designed to accept the signals from electrically isolated Series 400 probes
	manufactured by Yellow Springs Incorporated. Interchangeable probes in this series may be
	used for esophageal, rectal, skin or surface, or airway temperature measurement. Probes are
	furnished with a standard 10-feet lead. Extension leads are available.
	The signal from the probe is conditioned by the monitor’s input circuitry, processed, and used
	to drive the numeric display.

11-10Training