User's Manual Part 2

6-24
6.4. Non Invasive Blood Pressure Monitoring
This monitor uses the oscillometric method for measuring non-invasive blood pressure (NIBP).
This measurement can be used for adults, pediatrics and neonates, however to clarify, for
purposes of NIBP operation, the term “Pediatrics” does not include neonates. The oscillometric
technique applies specific algorithmic adaptations for neonatal cuffs and pulse levels. While
adult and pediatric patients (excluding neonates) share the same algorithmic settings for cuff
and pulse signal ranges. There is a range of cuff sizes offered for neonatal patients (four
sizes), all labeled for neonates. Patients with larger limbs than the neonatal types fit, will use
the larger sizes and operate in the Adult pediatric range. See section 9.
Automatic non-invasive blood pressure monitoring uses the oscillometric method of
measurement. This principle does not use sounds, but rather measures cuff pressure
oscillation amplitudes created by blood pulsations which vary as external cuff pressure passes
from above systolic to below diastolic. Oscillations are caused by blood pressure pulses against
the cuff with the largest oscillation signal by definition occurring when the cuff pressure equals
the mean arterial pressure (MAP). The systolic pressure is determined to be the cuff pressure
with an associated pulse amplitude of 72% of the maximum amplitude recorded at the MAP cuff
pressure, while diastolic is the cuff pressure associated with oscillations of 50% of the maximum
oscillation amplitude. The oscillation points for systolic and diastolic are empirically determined
and validated through testing.
In adult/Pediatric mode the initial inflation pressure is 160mmHG, while in Neonatal mode initial
inflation is 100mmHg. Subsequent pressure readings will use an inflation pressure of 30 above
the previously determined systolic pressure, or should no systolic be determined (patients
pressure too high as compared to the inflation pressure), inflation is 60mmHg above the MAP
reading. Further, in adult/pediatric mode only, there is an ability to increase inflation pressure,
during a given inflation cycle, should the algorithm determine that the patients systolic pressure
lies above the inflate pressure. In this case, cuff pressure will be increased to 40 mmHg above
the starting inflate pressure of this currently in process determination.
6.4.1. NIBP Overview
! WARNING
• Inaccurate measurements may be caused by incorrect cuff application or use. Make
sure the cuff is placed according to directions in this manual and the cuff directions for
use.
• Rapid, prolonged cycling of an oscillometric, noninvasive blood pressure monitor cuff
has been associated with any or all of the following: ischemia, purpura, or neuropathy.
Periodically observe the patient to make sure that their circulation is not impaired.
• Do not place the cuff on an extremity being used for intravenous infusion or any area
where circulation is compromised or has the potential to be compromised. As with all
automatically inflatable blood pressure devices, continual cuff measurements may
cause injury to the patient being monitored. Weigh the advantages of frequent
measurement against the risk of injury.
• Be sure to select the correct patient category setting for your patient before
measurement. Do not apply the adult/pediatric settings for neonatal patients.
• Artifacts from patient movement, common arrhythmias, premature beats, or fibrillation
may affect NIBP readings.
• Ensure the NIBP hose does not get kinked or occluded. Continuous NIBP cuff pressure
unable to be relieved may result in injury to the patient.
• Do not apply the blood pressure cuff to the same extremity as one to which a SpO
2
sensor to an infusion or IBP catheter is attached. Cuff inflation can disrupt the infusion,
IBP or SpO
2
monitoring and lead to alarms.