GE Medical Systems marquette Dash 2000, Руководство оператора, Страница: 187 / 272

Revision C Dash 2000 Patient Monitor 10-3
2005873-001
GENERAL CAUTIONS
Accuracy of NBP measurement depends on using a cuff of the
proper size. It is essential to measure the circumference of the
limb and to choose the proper cuff size.
The pulse rate derived from an NBP determination may differ
from the heart rate derived from an ECG waveform because
the NBP parameter measures actual peripheral pulses, not
electrical signals or contractions from the heart. Differences
may occur because electrical signals at the heart occasionally
fail to produce a peripheral pulse or the patient may have poor
peripheral perfusion. Also, if a patient's beat-to-beat pulse
amplitude varies significantly (e.g., because of pulsus
alternans, atrial fibrillation, or the use of a rapid-cycling
artificial ventilator), blood pressure and pulse rate readings
can be erratic, and an alternate measuring method should be
used for confirmation.
GENERAL NOTES
A patient's vital signs may vary dramatically during the use of
cardiovascular agents such as those that raise or lower blood
pressure or those that increase or decrease heart rate.
Automatic noninvasive blood pressure monitoring uses the oscillometric
method of measurement. To understand how this method works, we’ll
compare it to the auscultative method. With auscultation, the clinician listens to
the blood pressure and determines the systolic and diastolic pressures. The
mean pressure can then be calculated with reference to these pressures
as
long as the arterial pressure curve is normal.
Since the monitor cannot hear the blood pressure, it measures cuff pressure
oscillation amplitudes. Oscillations are caused by blood pressure pulses
against the cuff. The oscillation with the greatest amplitude is the mean
pressure. This is the most accurate parameter measured by the oscillometric
method. Once the mean pressure is determined, the systolic and diastolic
pressures are calculated with reference to the mean.
Simply stated, auscultation measures systolic and diastolic pressures and the
mean pressure is calculated. The oscillometric method measures the mean
pressure and determines the systolic and diastolic pressures.