Comparison of iNIBP linear inflation
method and conventional deflation method
non-invasive blood pressure measurement
in hemodialysis patients
Nobuto Hokama
Clinical Engineer, JA Nagano Koseiren Minami Nagano Medical center
Shinonoi General Hospital, Nagano, Japan

Background

About iNIBP

In patients undergoing hemodialysis, the treatment cancause hemodynamic variations which affect the bloodpressure. Also, the cuff attachment and repeated inflationsof non-invasive blood pressure ( NIBP) measurement
can be stressful. Nihon Kohden’s iNIBP linear inf lation
technology NIBP measurement has the advantages of shortermeasurement time with only the lowest necessary cuff
pressure. This can be useful for dialysis patients.

iNIBP completes the measurement while slowly inflating the cuff,
then deflates the cuff as soon as SYS is determined. As compared tothe deflation method which sets the target inflation pressure basedon the previous SYS, the iNIBP measurement time is shorter andinflation pressure is lower.
Cuff pressure (mmHg)

Deflation
methodiNIBP

Target inflationpressure

Lower pressure
SYS

Deflationmeasurement
completes

iNIBP

measurement
completes

DIA

ObjectiveWe evaluated the usefulness of iNIBP during hemodialysis.

Time (sec)

Shorter
measurement time

Methods
NIBP was measured by one of the two methods before,
during and after dialysis on a given day. Statistical difference
between each method was determined by Student’s t-test andMann-Whitney U test.
Significant difference was defined as P < 0.05. Pain intensity
was measured by the numeric rating scale (NRS).
Measurement Items

Example of measurement schedule using 2 different methods
Deflation
methodiNIBP

MondayWednesday

Friday0-10 Pain intensity (NRS)
Nopain0

Mild pain

12

Moderate pain

3456

Severe pain

78 9 10Evaluated Devices
Conventional Method

Systolic blood pressure (mmHg)
Diastolic blood pressure (mmHg)
Mean blood pressure (mmHg)
Pulse rate (bpm)
Arrhythmias
Measurement time (s)Maximum inflation
Pressure (mmHg)
Excess pressure=(max inflation pressure - SYS*) (mmHg)
NRS

iNIBP

DeviceDialysis unit

Nihon Kohden bedside monitor

Measurement principle

Oscillometric method

Oscillometric method

Measurement method

Conventional deflation method

Linear inflation and deflation method

Accuracy±3 mmHg

±3 mmHg

Inflation range

10–300 mmHg

0–300 mmHg

Cuff-YAWARA CUFF 2*SYS: Systolic blood pressure

Resultsn=160
ConventionaliNIBP

P value

Systolic blood pressure (mmHg)

136±19140±240.21

Diastolic blood pressure (mmHg)

76±1277±120.50

Mean blood pressure (mmHg)

95±1898±170.37

Pulse rate (bpm)

73±11

76±170.21

Arrhythmias (%)

30±50

10±300.10

Measurement time (s)31±1422±11<0.01

Max inflation pressure (mmHg)

192±19159±25<0.01

Excess pressure = (max inflationpressure – SYS) (mmHg)

51±2519±16<0.01

Student’s t-test for above items

NRS

1.3±1.5

0.8±1.40.011

Mann-Whitney U test for above item

Population

Number of patients: 17 (8 male and 9 female)
Average age: 65 ±12 (34-79)
Average time on dialysis: 7 years 8 months ±6 years
NRS4
1%

NRS4
5% NRS5
5%
NRS3
5%

NRS1
24%

NRS71%

NRS3
10%

NRS0
42%

NRS2
19%

NRS5
3%

NRS2
7%
NRS1
13%

Conventional
method

NRS0
65%

iNIBP

NRS0
NRS1
NRS2
NRS3
NRS4
NRS5
NRS6
NRS7

Figure 1. Distribution of NRS values during NIBP measurement

Comparison of iNIBP linear inflation method and conventional deflation method
non-invasive blood pressure measurement in hemodialysis patients

Discussion
Compared to the conventional method, iNIBP had a higher proportion of zero pain NRS 0 ratings (Figure1) which means less stressful measurement. In dialysis patients receiving multiple NIBP measurements,
blood pressure can vary greatly between measurements. Compared with the conventional method, iNIBP
measurement time tended to be less affected by blood pressure variation. This means that iNIBP can provide
measurement in a shorter amount of time even during sudden blood pressure changes (Figure 2).
Excessive cuff pressure and long measurement time can cause patients stress but iNIBP was able to provide amild and comfortable measurement environment (Figure 3).
What is less stressful NIBP measurement?
Measurement Time(s)100Conventional method
iNIBP

80
604020-80-60-40-20

020406080

Difference from Previous Measurement(mmHg)

Figure 2. Blood pressure differnce from the previousmeasurement and measurement time

Comfortable measurement
Meximum Inflation Pressure(mmHg)

Shorter and more constant measurement time
250

Conventional method
iNIBP

200150100500020406080100

Measurement Time(s)Figure 3. Measurement time and maximum inflation pressureSummary• Patients tended to feel less pain during NIBP measurement with the iNIBP method.
• The maximum inflation pressure of the iNIBP method was nearly equal to the systolic pressure; this contributed toa shorter measurement time.
• By reducing the measurement time and inflation pressure and keeping the measurement time constant, iNIBP
relieved the stress of blood pressure measurement in patients undergoing hemodialysis.
• iNIBP can benefit medical staff involved with dialysis by delivering operating efficiency for patients with frequent
NIBP measurement and fast NIBP results during sudden blood pressure drop.

Conclusion
Blood pressure measurement with iNIBP can be beneficial for dialysis patients.
This report is from a presentation at the 26th Congress of Japan Association for Clinical Engineers and the 61st Annual Meeting of the Japanese Society for Dialysis Therapy.

About the Use of Disposable Cuffs in Our Facility
In our dialysis center, we usually use reusable cuffs but after the abovementioned dialysis congress, we tried Nihon
Kohden’ s newly released disposable cuffs. These disposable cuffs have a thin vinyl chloride surface that iswater-repellent, easy to clean and low maintenance.
The Guidelines for Standard Hemodialysis Procedure and Prevention of Infection in Maintenance Hemodialysis
Facilities (4th ed) call for stricter measures to prevent the transmission of pathogens so our facility would also like to
use disposable NIBP cuffs as one infection-control measure against hepatitis virus, HIV, MRSA, and other pathogens.

Atari9271 SP67-0049 ’17.11. CLB. A.