OPTICAL FIBER CHARACTERIZED WITH A LOW

REFRACTIVE INDEX CAN DETECT BLOOD

Blood Increased Light Loss through an Air–cladding Optical Fiber

Akihiro Takeuchi, Tomohiro Miwa

Department of Medical Informatics, School of Allied Health Sciences, Kitasato University, Sagamihara, Japan

Graduate School of Medical Sciences, Kitasato University, Sagamihara, Japan

Minoru Sawada, Haruo Imaizumi, Hiroyuki Sugibuchi, Minoru Hirose, Noriaki Ikeda

Junkosha Co., Ltd., Ishibashi, Sakaigawa, Fuefuki, Yamanashi, Japan

Department of Clinical Engineering, School of Allied Health Sciences, Kitasato University, Sagamihara, Japan

Department of Medical Informatics, School of Allied Health Sciences, Kitasato University, Sagamihara, Japan

Keywords: Air-cladding plastic optical fiber, Light loss, Venous needle dislodgement.

Abstract: Large amounts of undetected blood loss during hemodialysis are caused by venous needle dislodgement. A

special air-cladding plastic optical fiber with a low refractive index, fluoropolymer, PFA fiber, JUNFLON

was developed to monitor oil and lipid leakage in industrial fields, and to monitor the dust in the air in clean

rooms. To apply the air-cladding plastic optical fiber as a bleed sensor, we studied the optical effects of

soaking the fiber with various liquids and porcine blood on light-loss experimental settings. Light intensity

through the fiber was studied with a light emitting diode and a photodiode under various conditions of

soaked fiber with reverse osmosis water, physiological saline, glucose, and porcine blood. The more the

soaked length increased with all mediums, the more the light intensity decreased. Although the slopes of the

decreased curves varied according to the mediums, the light scattering phenomena caused by the mediums

can be applied to a bleed sensor for clinical use.

1 INTRODUCTION

Although hemodialysis has evolved into a safe and

less stressful procedure for both patients and

caregivers (Sarkar, Kaitwatcharachai and Levin,

2005; Hawley, Jefferies, Nearhos and Van Eps,

2008), intradialytic complications still cause

considerable patient morbidity and rarely, mortality

(Sarkar et al., 2005). Venous needle dislodgment

(VND) is one of the most serious accidents that can

occur during hemodialysis (Hawley et al., 2008; Van

Waeleghem, Chamney, Lindley and Pancírová,

2008). The European Dialysis and Transplant Nurses

Association/ European Renal Care Association has

produced 12 practice recommendations to help

reduce the risk of VND and detect blood leakage as

soon as possible (Van Waeleghem et al., 2008). A

safety device from Redsense Medical, Halmstad,

Sweden for use during hemodialysis that uses fiber

optic technology to detect blood has been approved

as a Class I medical device with the intended

purpose of detecting VND (Van Waeleghem et al.,

2008; Ahlmén, Gydell, Hadimeri, Hernandez,

Rogland and Strömbom, 2008).

On the other hand, optical fibers are widely and

directly used in fiber optic communications, medical

endoscopes, and sensors (Goodyer, Fothergill, Jones

and Hanning, 1996; Zubia and Arrue, 2001; Sugita,

2001; Lee, 2003). An optical fiber generally consists

of a core and a surrounding layer called “cladding”

with a low refractive index. Based on the difference

in refractive indices, light is reflected at the

core-cladding interface. An air-cladding plastic

optical fiber characterized with a low refractive

index of 1.328 nD was developed by the Junkosha

Co., Ltd. (Yamanashi, Japan), that can monitor

contaminates or impurities in a clean room or

environs (Suzuki, 2004). When the air-cladding

optical fiber is contaminated with a liquid, the light

307

Takeuchi A., Miwa T., Sawada M., Imaizumi H., Sugibuchi H., Hirose M. and Ikeda N..

OPTICAL FIBER CHARACTERIZED WITH A LOW REFRACTIVE INDEX CAN DETECT BLOOD - Blood Increased Light Loss through an Air–cladding

Optical Fiber.

DOI: 10.5220/0003122003070310

In Proceedings of the International Conference on Biomedical Electronics and Devices (BIODEVICES-2011), pages 307-310

ISBN: 978-989-8425-37-9

 2011 SCITEPRESS (Science and Technology Publications, Lda.)

signal may partially be lost from the contaminated

site and may decrease when the area contaminated

with the liquid increases. Hence, it would be

possible to detect bleeding by monitoring the light

loss from the air-cladding plastic optical fiber

attached to the skin around the needle site of a

patient’s arm or leg. To our knowledge, any

relationship between lengths of the segment soaked

with a liquid and light loss has not yet been reported

in either PubMed or Optics InfoBase literature, nor

has utilizing this particular relationship to detect

VND been reported. The present study presents the

optical characteristics of air-cladding optical fiber to

detect blood or fluid leakages.

2 MATERIALS AND METHODS

2.1 Experiment Overview

Figure 1 shows an experimental work desk on which

an optical fiber was placed with a straight segment

to test the effect the mediums have on the optical

fiber. The working area was strictly cleaned to

prevent any contamination from other mediums, e.g.,

dust, hand oils, or any liquids.

The examined air-cladding optical fiber is a

fluoropolymer, PFA core fiber, JUNFLON

(Junkosha), with a 1-mm diameter, and a refractive

index of 1.328 nD. The fiber used in this experiment

was 2 m in length and weighed 2 g. It was resistive

to acids and alkalines, and to ethanol, ethylene oxide

gas, and heating for sterilization.

The sensor module, LEAKLEARN OPT

(Junkosha), consisted of a light emitting diode

(LED), a detector photodiode (PD), and electrical

circuits for monitoring and alarming. The sensor

module monitors voltage as light intensity. Thus, the

voltage decreases as the light transmitted to the PD

becomes darker.

2.2 Mediums used to Soak the Optical

Fiber

The applied liquids were: reverse osmosis (RO)

water, physiological saline, and glucose in water at

5%, 10% and 20%. All of which except the RO

water were pharmaceutical products. Porcine plasma

and blood (Hct 40% and 20%) were also applied and

tested in the same manner. The hematocrits were

prepared by adding porcine plasma but not saline.

To control a length of fiber soaked with a medium

without a longitudinal leak under the fiber, narrow

gauze strips were crossed over the fiber or wrapped

around the fiber. Then each medium was manually

dripped on each gauze strip. The mediums, thus,

soaked the gauze strips and circumferentially

surrounded the fiber for the whole width of the strips.

There was no expansion observed of the mediums

along the fibers.

For physiological saline, light intensities were

compared with two settings, the continuous and the

separate modes, of the gauze strips on the fiber. The

soaked lengths were the sum of the widths of the

gauze strips in the separate mode. For other

mediums, the light intensities were measured in the

continuous mode on the fibers.

Figure 1: Experimental setting.

Figure 2: Light intensity to soaked length for each test

medium. The horizontal axis indicates the soaked length in

centimeters.

3 RESULTS

Figure 2 shows all of the raw data obtained for each

medium tested. Data points for all experiments

including duplicates are shown with 5 symbols for

the 5 experiments. The light intensities clearly and

exponentially decreased with the longer soaked

length for all the mediums. For physiological saline,

BIODEVICES 2011 - International Conference on Biomedical Electronics and Devices

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the raw data of the continuous mode were visually

the same as those of the separate mode. Porcine

plasma showed a slightly steeper curve than did the

porcine blood. The raw data of RO water showed a

milder decreasing curve than did those of the other

mediums.

4 DISCUSSION

The light intensity decreased as the length soaked

with the medium increased. Although Golnabi and

Azimi (2007) proposed a plastic optical fiber

leakage sensor by immersing liquids with the higher

index of refraction, the quantitative relationship

between soaked lengths and light loss was not

reported in detail in their study.

The phenomenon of scattering back to the front

end of a fiber is also utilized as a sensor, optical time

domain reflectometry (OTDR) (Sugita, 2001).

Although the OTDR is also widely used in medical

and chemical analyses and molecular biotechnology

(Lee, 2003; Barnoski and Jensen, 1976; Sensfelder,

Bürck and Ache, 1998), it is difficult for

commercially available OTDR to detect any clinical

events in a region less than 1 m from the sensor

module. The mechanism of our sensor is simpler

than that of OTDR, and only based on light intensity

without any chemical modifiers to sense bleeding or

liquids. The phenomena that the decrease of light

intensity depends on the length soaked can be

applied to monitor VND.

Although it is well known that bending a fiber

modifies its guiding properties and increases light

loss, the optical fiber used in the present study

showed no light loss even when bending it in a

1-cm-diameter loop. This flexibility would be useful

for attaching the optical fiber to the skin around a

needle site of a patient’s arm or leg.

The optical fiber can be used as a non-invasive

disposable sensor to detect bleeding or leakage

during hemodialysis. The optical fiber was looped

on the surface of the skin around the puncture site

(Figure 3). Although the sensor can detect bleeding

from the needle site, it can not sense a subcutaneous

bleeding.

Although this sensor module may be made

smaller while maintaining its sophisticated functions

for clinical use, the air-cladding optical fiber offers

certain advantages, such as the fiber’s light weight,

flexibility, and the ability to adjust the fiber length,

loop size, and route, simple fixation with surgical

tape, and continuous real-time sensing. These

advantages allow the air-cladding optical fiber to be

used as a disposable sensor to quickly detect

bleeding and leakage during hemodialysis and

continuous venous infusion.

Figure 3: Clinical setting during hemodialysis. The optical

fiber was attached with 3M tape to the skin and partially

passed through a white tube.

5 CONCLUSIONS

We confirmed the phenomenon that light intensity

clearly decreased as the soaked length of a fiber

increased. This phenomenon can be used to quickly

detect bleeding and leakage and set off alarms for

patients undergoing hemodialysis and for those

receiving infusion therapy.

ACKNOWLEDGEMENTS

The authors thank Robert E. Brandt (CEO, MedEd

Japan) for helpful advice on the English language in

the preparation and editing of this manuscript.

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