GE CareScape V100, Service Manual

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2048723-002C CARESCAPE V100 Vital Signs Monitor 2-9
Equipment overview: Overall principles of operation
has one valve, which is used to deflate the cuff. Valve control is through the Main
Board. When the cuff pressure data acquisition for the determination is
complete, the processor on the Main Board calculates the systolic NIBP, the
diastolic NIBP, the Mean Arterial Pressure (MAP), and the pulse rate. The results
are then displayed on the UI Board and sent to the printer (if the user presses the
Print button).
The Pneumatics are controlled by the NIBP processor. The NIBP processor
monitors pressure information from PT2. If an over-inflation condition occurs,
the OVERPRESSURE signal is routed to the Pneumatics to release the air
pressure. The Main Board also generates an alarm condition with the speaker
sounding and error code message on the UI Board.
DINAMAP SuperSTAT algorithm
The oscillometric method of determining NIBP is accomplished by a sensitive
transducer which measures cuff pressure and pressure oscillations within the
cuff. For the first determination taken on a patient, the algorithm stores the
pattern of the patient's oscillation size as a function of the pressure steps. For
subsequent manual, auto, or Stat determinations taken within 2 minutes of a
previous determination of the same patient, as few as four pressure steps may
be necessary to complete the determination process. In auto mode the data is
stored for up to 16 minutes. When employing fewer pressure steps, the system
uses the stored information from the previous blood pressure determination to
decide the best pressure steps to take. The algorithm measures the consistency
of pulse size to tell if the oscillations taken at a step are good and if more steps
are needed.
The first determination settles at an initial target pressure of 135 mmHg (adult
mode) and 100 mmHg (neonate mode), depending on initial target pressure
preset. To allow for rapid settling of cuff pressure, the monitor will momentarily
inflate to a higher pressure then immediately deflate to the target pressure. After
inflating the cuff, the NIBP parameter begins to deflate. The oscillations versus
cuff pressure are measured to determine the mean pressure and calculate the
systolic and diastolic pressures.
During an NIBP determination, the parameter deflates the cuff one step each
time it detects two pulsations of relatively equal amplitude. The time between
deflation steps depends on the frequency of these matched pulses (pulse rate of
the patient). However, if the monitor is unable to find any pulse within several
seconds, it will deflate to the next step. The process of finding two matched
pulses at each step provides artifact rejection due to patient movement and
greatly enhances the accuracy of the monitor. The figure shows a full
determination sequence for an adult patient. In
Stat mode, some steps may
require only one pulse.