3.10 Continuous Non-Invasive Blood Pressure Measurement
165
Then the dPWTT threshold decreases very slowly, which ensures that blood pressure
measurement starts even with a stable PWTT value. Due to this, the maximum interval be-
tween blood pressure measurements does not exceed 3-4 hours
When setting a fixed threshold dPWTT, an extraordinary start of blood pressure will be per-
formed after dPWTT goes beyond the specified limits, regardless of other factors.
For an extraordinary start of blood pressure, it is necessary that the value of dPWTT exceeds
the threshold for a time of 5 s or more. This condition is fulfilled regardless of the type of the
threshold and ensures the channel stability against short-term PWTT fluctuations.
3.10.3. Continuous Arterial Blood Pressure Calculation
Arterial pressure in the cNIBP channel is calculated based on the current coefficients of the ap-
proximating straight line and the current PWTT value. The coefficients of the approximating
straight line reflect the dependence of arterial pressure on the PWTT value.
To calculate blood pressure, the results of several NIBP measurements and the corresponding
PWTT values are used. This approach allows reducing the influence of errors in single meas-
urements of NIBP on the value of the coefficients. The results of calibration measurements are
taken into account with weighting factors that take into account the reliability and age of the cor-
responding result. Due to this, more recent results usually contribute more to the calculation of
the coefficients of the straight line. In addition to the dependence of blood pressure on PWTT,
according to the results of the same measurements, the relationship between the values of sys-
tolic, diastolic and mean pressures is also determined. These ratios allow the device to calculate
all three values of blood pressure.
Due to the fact that the continuous calculation of blood pressure takes into account the results
of several calibration measurements, the results of cNIBP are more stable and less sensitive to
artifacts than the results of measurements on the cuff. This also explains the fact that cNIBP
results obtained immediately after calibration usually do not match the results of the last NIBP
cuff measurement.
When the continuous NIBP mode is disabled, the cNIBP channel is calibrated only after routine
blood pressure measurements. If there is sufficient information to calculate the coefficients of
the straight line, then the cNIBP values are calculated. Extraordinary blood pressure measure-
ments are not started at the same time.
Summary of Contents for MPR6-03
Page 1: ...Patient Monitor MPR6 03 User Manual RM 501 01 000 01 01 UM Version 7 05 2020 ...
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