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Example configuration - APR31a  PDF   Settings - APR31a
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Input

The module has one input.

  • The sampling frequency of the input signal must be within a 100-1000 Hz range.
  • When APR31a is used as a trigger for AFL30a (arterial flow analyzer), the sampling frequency of arterial flow signal should not exceed 500 Hz.

Outputs

Parameters
  • All outputs are computed on a cycle-by-cycle basis (except the Analysis error event). A cycle onset and offset are determined respectively by the previous and the current diastole points.
  • For experiments with rapid changes in pulse pressure and a heart rate above 600 bpm, cycles may be missed without generating any Analysis Error marker.

 

Parameters

Units

Description

Location

Systolic

mmHg

Systolic blood pressure.

Systolic pressure point.

Diastolic

mmHg

Diastolic blood pressure.

Diastolic pressure point.

Arithmetic Mean

mmHg

Arithmetic mean of signal samples [1] using the following formula:

Systolic pressure point.

Quadratic Mean

mmHg

Quadratic mean of signal samples using the following formula:

Systolic pressure point.

Approximated Mean

mmHg

Mean pressure computed using the following formula:

Systolic pressure point.

Rate

bpm

Instantaneous heart rate computed as: 60/(Beat Interval/1000) (see definition below).

Systolic pressure point.

Beat Interval

ms

Duration between previous and current systole positions.

Systolic pressure point.

Pulse Pressure

mmHg

Amplitude between systolic and diastolic pressures of the current cycle.

Systolic pressure point.

Analysis Error

 

Time event generated when one of the following condition is met:

  • absence of systolic pressure value,
  • absence of diastolic pressure value,
  • instantaneous rate outside the 13.3-800 bpm range (i.e. 0.075-4.5 s for Beat Interval),
  • 4-fold change in Pulse Pressure detected between the current cycle and a previous cycle included in “the last 5 cycles before the 2 preceding ones”,
  • external perturbation (saturation, high frequency spike, flat signal, etc.). Following a period of abnormal signal, a 10s delay (maximum) may occur before reinitializing detection.

No parameter computed.

On the cycle (systolic or diastolic pressures not detected) or on the previous valid cycle (abnormal event).
Only one marker per detected abnormal event.

[1] Ream A.K. Mean blood pressure algorithms. J. Clin Monit. 1985; 1: 138-144

Response time

Outputs are available after a delay [5-14 s] from signal acquisition.

 

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