Factors Affecting Nibp Measuring; Clinical Limitations - Gima 35132 Manuel De L'utilisateur

the Korotkoff Sound Method in less error, higher reliability and stability. Their differences may be reflected in the
following aspects.
1. The measures by the Korotkoff Sound Method are liable to effect of human factors. For example, different
people may have different sound judging ability, or different reactivity when listening to heart sound and
reading mercury meter. The air release speed and subjectivity may also affect the judgment. By the
oscillating method, the computation is accomplished by the computer, thus relieving the possibility of
effect due to human factor.
2. With the Korotkoff Sound Method, the measure is taken on the basis of appearance and disappearance of
heart sound. The air release speed and heart rate may have direct effect on the measurement accuracy. It
also has the disadvantages of rapid air release and poor accuracy. In the contrast, with the oscillating
method, the determination is calculated on the basis of cuff pressure oscillatory waveform envelope, and
the air release speed and heart rate has little effect on the measurement accuracy.
3. Statistics show that, when measuring the hypertension, the measure taken by the oscillating method is
likely to be lower than that taken by the Korotkoff Sound Method. When measuring the hypotension, the
measure taken by the oscillating method is likely to be higher than that by the Korotkoff Sound Method.
But, it doesn't mean the advantages or disadvantages between the oscillating method and the Korotkoff
Sound Method. Comparison with the results taken by more accurate method, let's say comparison of the
invasive pressure result with the output value by the blood pressure measuring simulator, will show which
method has more accurate results. In addition, higher or lower value should be a statistical concept. It is
recommended those used to adopt the Korotkoff Sound Method use different physiological calibration for
values determined by the oscillating method.
4. The studies have shown that the Korotkoff Sound Method has the worst accuracy when it comes to
measurement of hypotension, while the oscillating method has worse accuracy when it comes to
measurement of controlled hypertension relief.

8.1.2 Factors affecting NIBP measuring

Select a cuff of appropriate size according to the age of the subject.
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Its width should be 2/3 of the length of the upper arm. The cuff inflation part should be long enough
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to permit wrapping 50-80% of the limb concerned.
Prior to use of the cuff, empty the cuff until there is no residual air inside it to ensure accurate
measurement.
Make the cuff mark φ in the position where artery pulsates obviously, the effect will be best.
The lower part of cuff shall 2cm above the elbow joint.
Do not wrap the cuff on too thick clothes(especially for cotton-padded clothes and sweater ) to take
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measurement;
The testee shall lie in bed or sit in chair, make the cuff and heart at the same level, the result will be
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most accurate, other postures may have inaccurate result;
During measuring, do not move your arm or the cuff;
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The measuring interval shall longer than 2 minutes, in continuous measurement, too short interval
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may cause arm extrusion, blood quantity increases, then cause blood pressure increases.
Keep the patient still and stop talking before and during measuring;
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The patient's mood also can affect the measuring result, when exciting, the blood pressure goes up.
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The measuring result also affected by time, lower in the morning and higher in the evening;
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8.1.3 Clinical Limitations

User Manual for Vital Signs Monitor
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