Usefulness of Linear Inflation Method NIBP (iNIBP)
during Induction of Anesthesia
Naoyuki Hirata, MD, PhD
Sapporo Medical University Hospital, Department of Anesthesiology, Japan

Introduction
NIBP (non-invasive blood pressure) is a low invasive, high accuracy parameter which is essential inhemodynamics monitoring. However, many anesthesiologists are unsatisfied with NIBP measurement.
Specifically, after induction of general anesthesia, after tracheal intubation, or in situations such as unexpected
bleeding, anesthesiologists want to know the blood pressure right away and get frustrated waiting for ameasurement result. Every second counts in clinical anesthesia and a small delay of a few seconds is a longtime.

New Technology
In conventional NIBP measurement, the cuff is rapidly inflated to a pressure above systolic then gradually
deflated while detecting the oscillations in the cuff corresponding to the arterial pulse (step-deflation method).
In a newly developed linear inflation method (iNIBP), non-invasive blood pressure is measured during thecuff inflation stage. If iNIBP does not detect
the oscillations during inflation, monitoringautomatically switches to step-deflation
method.
In one study 1), the linear inflation methodcompleted measurement in 13.0 ± 2.3 seconds
as compared to 32.7 ± 13.6 seconds for the step-iNIBP

Cuff pressure (mmHg)

Deflation
methodTarget inflationpressure

Lower pressure
SYS
DIA

iNIBP

measurement
completes

Deflationmeasurement
completes

deflation method. This small reduction of only
20 seconds is important for anesthesiologists.
In our study, we assessed the usefulness ofShortermeasurement time

Time (sec)iNIBP in hemodynamically unstable patients
undergoing general anesthesia.

Figure 1. iNIBP method and step deflation method

Methods
Our study included 14 surgery patients receiving tracheal intubation under general anesthesia. Blood pressure
was continuously measured with iNIBP from before induction of anesthesia until 1 minute after intubation.
We recorded the percentage of successful iNIBP measurements (measurements not switching to step-deflation
method) during anesthesia induction and the measurement times of linear inflation method and step-deflation
method. We also compared the maximum rate of change in blood pressure for the linear inflation and stepdeflation measurements to determine if the rate of blood pressure change had an effect on causing it to switch tostep-deflation method.

Usefulness of Linear Inflation Method NIBP (iNIBP) during Induction of Anesthesia

Results
Out of 326 total NIBP measurements (an average of 23.3 measurements per patient), the linear inflation method
successfully measured 91% of the measurements without switching to step-deflation method. Linear inflation
method had an average measurement time of 13.7 seconds. When it switched to step-deflation method, theaverage measurement time was 42.8 seconds. The maximum rate of change in systolic blood pressure was
12.9% (IQR 8-43) when measured with step-deflation method and 31.6% (IQR 22-40) when measured withlinear inflation method — not a significant difference. This suggests that change in blood pressure during theanesthesia induction period did not affect switching to the step-deflation method.

iNIBP in ECTAnesthesia induction with:- Thiamylal 175 mg- Suxamethonium 40 mg

BP (mmHg), Time (sec)We also evaluated iNIBP in a case of electroconvulsive
therapy (ECT). The measurement time was
15 seconds with the linear inf lation method
when the blood pressure slightly dropped after
induction of anesthesia. After the first stimulus,
there was a rapid 80 mmHg increase in systolicblood pressure (from 120 to 200 mmHg) and
100% of the measurements were performed
with linear inflation method (without switchingto step-deflation) with a measurement time ofabout 15 seconds (Figure 2).

Success rate ofmeasurement with theinflation mode: 100%ECTTime

Figure 2. Trend graph for the ECT case

Conclusion
Even during very unstable hemodynamics, the linear inflation method of iNIBP technology can provide NIBP
measurement at a frequency close to continuous NIBP measurement. This is useful during perioperativemanagement. iNIBP is a good measurement method for anesthesiologists who want to know the blood pressure
as quickly as possible when even 1 second makes a difference.
Reference1)

Onodera J, Kotake Y et al. Validation of inflationary non-invasive blood pressure monitoring in adult surgical patients.
J Anesth. 2011; 25: 127-30.

This report is based on a presentation given at the 53th Annual Meeting of the Japanese Society of Anesthesiologists,
Kyushu Region.

Atari9154 SP67-0020 ’17.9. CLB. A.