LIGHT TRANSMISSION THROUGH GAUZE PAD SOAKED

WITH BLOOD OR LIQUIDS TO DETECT VENOUS NEEDLE

DISLODGEMENT

Akihiro Takeuchi, Kai Ishida

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

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

Yasuo Morohoshi, Toshihiro Shinbo, Minoru Hirose, Noriaki Ikeda

Department of Laboratory Animal Science, Kitasato University School of Medicine Kitasato, Sagamihara, Japan

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

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

Keywords: Venous needle dislodgement (VND), Photo sensor, Light transmission, Gauze pad.

Abstract: Accidents during hemodialysis such as a large amount of blood loss are often caused by venous needle

dislodgement. To develop a bleeding sensor based on a photo sensor, we studied effects of liquids and

porcine blood on light transmission through a thin gauze pad. The photo sensor consisted of an ordinary

electrical circuit, a light emitting diode (lambda max = 645 nm), a photo diode, and a thin gauze pad placed

between the diodes. The light transmitted through the gauze pad soaked with liquids or porcine blood was

measured with a digital voltmeter. The liquids on a gauze pad, significantly increased the voltage (light

transmission) from 0.33 +/- 0.004 V (SD) to 0.63 +/- 0.02 V (minimum, by reverse osmosis water) and to

0.70 +/- 0.03 V (maximum, by 50% glucose). The porcine blood significantly decreased the voltage from

0.33 V to 0.21 +/- 0.02 V in Hct 40%, to 0.27 +/- 0.02 in Hct 30%, to 0.30 +/- 0.02 V in Hct 20%. We

confirmed that liquids significantly increased light transmission through the gauze pad, but porcine blood

decreased light transmission. This opposite response can be used to distinguish liquids from blood on a

gauze pad.

1 INTRODUCTION

Over the past three decades, 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). However,

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 HD

(PMID9859033, 1998; Hawley et al., 2005; Van

Waeleghem, Chamney, Lindley and Pancírová,

2008). The FDA has some statistics on cases of fatal

blood losses but the known numbers are probably

too low to reflect the real figures (Ahlmén, Gydell,

Hadimeri, Hernandez, Rogland and Strömbom,

2008). Ahlmén et al. estimate the incidence of

venous-needle dislodgements of 0.1% is merely an

approximation over a short period (Ahlmén, et al.,

2008). Although certain devices monitoring venous

pressure (Hertz, Joensson, Sternby), pressure pulse

(Goldau, Fresenius Medical Care Deutschland

GmbH) and moisture (Pierratos and Lugonzo, 2009)

(DRI Sleeper® Dr. Page. Retrieved Aug 20, 2009)

have been developed, tested and patented, a “VND

sensor” has been requested by patients and medical

professionals (European Dialysis and Transplant

Nurses Association/European Renal Care

Association (EDTNA/ERCA, 2005) has produced

12 practice recommendations to help reduce the risk

of VND and detect blood leakage as early as

possible (Van Waeleghem et al., 2008). A device

that uses fiber optic technology to detect blood has

been approved (CE marked) as a Class I medical

174

Takeuchi A., Ishida K., Morohoshi Y., Shinbo T., Hirose M. and Ikeda N. (2010).

LIGHT TRANSMISSION THROUGH GAUZE PAD SOAKED WITH BLOOD OR LIQUIDS TO DETECT VENOUS NEEDLE DISLODGEMENT.

In Proceedings of the Third International Conference on Biomedical Electronics and Devices, pages 174-177

DOI: 10.5220/0002738801740177

 SciTePress

device with the intended purpose of detecting VND

in extracorporeal circuits (Ahlmén J et al., 2008;

Van Waeleghem et al., 2008). The device has also

been granted FDA approval and is now available for

sale in the United States. However, other detection

systems are still under development at the present

time (Van Waeleghem et al., 2008).

Although there was no observed event that led to

dislodgement of the needle in most reported

episodes (Sandroni, 2005), the oozing of blood has

commonly been noticed on a tape or small gauze at

the needle site in hemodialysis (Lindsay, Burton,

1972; Salaman, 1971; Sandroni, 2005). The oozing

may be due to a brittle vessel and skin in chronic

renal failure patients. The oozing decreases the

adhesiveness between the tape and skin and could

lead to needle dislodgement. A small piece of gauze

is used to absorb the oozing blood at a needle site

and to avoid bloody soiling of clothes and bed sheets.

We attempted to sense the small amount of blood

on a small gauze pad that covers the needle site. A

direct electronic sensor such as moisture or enuresis

detector is not suitable in Japan because they could

cause micro electrification. Processing an optical

fiber to a blood sensor is technically difficult for our

laboratory, and the fiber is already used in the

convenient device above. Although it is easy to

imagine that light transmission through gauze might

be changed by blood, we could not find a practical

report of light transmission affected by blood or

other liquids.

To detect an accidental bleed in hemodialysis, we

made a photo sensor module to measure light

transmitted through gauze pad and studied the

effects of blood and liquids on a light transmission.

2 METHODS

2.1 Light Sensory Module

The sensory module consists of a light emitting

diode (LED, lambda max = 645 nm, 55 mcd,

HLMP-Q105), a photo diode (PD, spectrum 600-

1050 nm, DIL-BPW34) on a simple circuit that is

commonly used in light/dark sensors (Figure 1). The

Figure 1: The circuit of photo sensor module.

PD changes its resistance depending on the intensity

of the light transmitted. The voltage across the

resistance R2 (12 k ohm) increases when the light is

bright and decreases when it is dark. The voltages

are measured with a digital voltmeter. The LED and

PD are attached at the edges of a plastic clip and

sealed with bond to avoid any short-circuits that

could be caused by the liquids. The voltages were

not changed by any background illumination such as

that from a desk lamp because the strong LED light

was shown directly through the gauze pad to the PD.

2.2 Gauze Pad and Test Medium

Loose weave pads was a piece of gauze (Blood Ban,

L size, Yutoku Pharmaceutical Industry, Ltd., Japan)

used after collecting blood or administering infusion

such as a “BAND-AID.”

Test mediums in the amount of 0.3 ml were

manually dropped in the center of the gauze pad

(Figure 2). The applied liquids were a reverse

osmosis water, physiological saline, and glucose in

water at 5%, 10%, 20%, 40% and 50%. Porcine

plasma and blood were also applied and tested in the

same manner. The hematocrits (40%, 30% and 20%)

were prepared by adding porcine plasma but not

saline. The porcine blood was obtained from a

slaughterhouse (Tokyo Shibaura Zoki Ltd., Tokyo

Japan).

2.3 Statistics

For each liquid, seven measurements were collected

and presented with a mean and SD. For each porcine

blood, five measurements were averaged as one

value. Nine values were collected for each blood

sample and presented with a mean and SD. They

were statistically compared with the control values

using unpaired Student’s t-test. A probability level

of P < 0.05 was considered to indicate statistical

significance.

LIGHT TRANSMISSION THROUGH GAUZE PAD SOAKED WITH BLOOD OR LIQUIDS TO DETECT VENOUS

NEEDLE DISLODGEMENT

175

Figure 2: Experiment of dropping porcine blood on a tight

weave pad thin gauze pad.

3 RESULTS

Mean voltage was 0.332 +/- 0.004 V under control

condition. Liquids and porcine plasma increased the

voltages from 0.332 +/- 0.004 V to 0.634 +/- 0.018

V (minimum, by a reverse osmosis water) and to

0.703 +/- 0.027 V (maximum, by 50% glucose)

(Figure 3). The light transmitted through the gauze

pad was increased by liquids or plasma. There was a

higher concentration of glucose the more the light

transmission increased. Porcine blood decreased the

voltage from 0.332 V to 0.214 +/- 0.019 V in 40%

Hct, to 0.271 +/- 0.023 in 30% Hct, to 0.304 +/-

0.019 V in 20% Hct. The higher the concentration of

Hct, the more the light transmission decreased.

4 DISCUSSION

Studies of incidents showed that the typical scenario

of VND episodes happened in apparently routine

treatments and with fully staffed units (Sandroni,

2005). Although a needle and needle tubing are

stabilized with an adhesive fabric and the “chevron”

technique (Van Waeleghem et al., 2008), VND

occurs in hemodialysis. In the present state, medical

staffs are required to find accidents as quickly as

possible.

Liquids or plasma increased light transmission

through gauze pad. It may be the same effect as

when light is seen through a wet shirt. A part of the

light from a light source, the LED, was scattered

outward in the gauze as a bulk scatter. The residuals

hit the PD. The liquids dropped on the gauze pad

could reflect the light traveling inward. The light

transmissions increased proportionally to the glucose

concentrations. The relationship is probably due to

the Beer-Lambert’s law.

Porcine blood clearly decreased the light

transmission through the gauze pad. The decreases

were related to their hematocrits. The absorbance of

light at a wavelength 645 nm was interpreted by a

higher concentration of haemoglobin. The opposite

response of light transmission caused by liquids or

blood may be used in theory to distinguish blood

from liquids such as sweat, infusion drip, urine,

saliva, or leaching solution. Although we have

attempted to develop a monitor tool to detect

bleeding in hemodialysis, the device may be used for

monitoring VND during a continuous intravenous

infusion for a relatively long time. In such a case,

even if venous blood flows and mixes at the needle

site, the infusion volume may be larger than that of

venous blood. It would be more desirable if the

device could quickly detect any change from the

control level rather than an absolute value of the

light transmission.

Although the optical device of Ahlmén et al.

(2008) can find a minute amount of blood (about 1

ml), it may be difficult to distinguish oozing from

bleeding. Our procedure may control the sensing

volume by an arbitrarily set gauze volume or

distance between the needle site and the sensor on a

gauze pad.

This study proved that the light was absorbed in

gauze pads with hemoglobin and that light

transmission increased in wet gauze pads without

hemoglobin. Although we should confirm that the

phenomenon is ordinary shown in other kinds of

gauze pad, more thin or thick, this fundamental

study will promote the development of simple

practical bleeding sensors to monitor hemodialysis

and continuous infusion. In a future plan, we will

consider a disposable or re-usable LED and PD

device to completely avoid any infection and short-

circuits, a power supply for four-hour hemodialysis

a day, three times a week, and how to alarm an event

to notify medical staffs.

5 CONCLUSIONS

We confirmed that liquids on a gauze pad

significantly increased light transmission through the

gauze pad, but porcine blood decreased light

transmission. These opposite effects of light

transmission through the gauze pad can be used to

distinguish liquids from blood on the gauze pad with

the bleeding sensor.

BIODEVICES 2010 - International Conference on Biomedical Electronics and Devices

176

Figure 3: Voltages across R2 with porcine blood and liquids in the gauze pad. Horizontal line 0.332 V shows the value at

the control condition.

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NEEDLE DISLODGEMENT

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