S- 1
TECHNICAL SUPPLEMENT
S1 Introduction
S2 Overview
S3 Stackbus
Interconnect
S4 Circuit
Analysis
S5 Schematic
Diagrams
S1
INTRODUCTION
This Technical Supplement provides the reader with a summary of the
N-3100 operating principles and an in -depth discussion of N-3100 circuits. A
functional overview and detailed circuit analysis are supported by block and
schematic diagrams. The schematic diagrams are located at the end of this
supplement.
S2 OVERVIEW
The N -3100 uses an oscillometric technique to provide noninvasive blood
pressure measurements at selected intervals. The N-3100 uses the inflatable
sphygmomanometer cuff similar to that used by clinicians in routine
auscultatory blood pressure measurements. The clinician normally inflates
the cuff manually, then deflates the cuff slowly, listening for Korotkoff’s
sounds associated with systole and diastole. The oscillometric technique uses
a pressure transducer and electronic data processing to determine systolic,
mean, and diastolic pressures.
A motorized pump inflates the cuff to approximately 180 mmHg (120 mmHg
for neonatal patients) initially. The N-3100 then deflates cuff pressure
gradually. A pressure transducer detects air pressure and sends a signal to
the measurement circuits. As pressure in the cuff is reduced, blood flows in
the previously occluded artery and the pressure read by the transducer
changes. The point at which oscillation increases sharply is defined as the
systolic pressure. As the cuff deflates further, oscillation amplitude increases
to a maximum, then decreases. The point of peak oscillation amplitude is
defined as the mean arterial pressure. The point at which the system detects
a rapid decrease in oscillation is defined as the diastolic pressure. Figure S2-1
shows the inflation and deflation process and the oscillation of the pressure
as seen by the transducer.
The N -3100 is factory-set to self-calibrate before every measurement.
