scholarly journals Optical Fibre Sensor for Simultaneous Measurement of Capillary Refill Time and Contact Pressure

Sensors ◽  
2020 ◽  
Vol 20 (5) ◽  
pp. 1388
Author(s):  
Chong Liu ◽  
Ricardo Correia ◽  
Hattan Ballaji ◽  
Serhiy Korposh ◽  
Barrie Hayes-Gill ◽  
...  
Keyword(s):  
Optical Fibre ◽  
Light Signal ◽  
Fibre Bragg Grating ◽  
Capillary Refill Time ◽  
Capillary Refill ◽  
Optical Fibre Sensor ◽  
Reflected Light ◽  
Integrated Optical ◽  
Normal Colour ◽  
Exponential Regression Model

The widely applied capillary refill time (CRT) measurement is currently performed by manually applying pressure and using a stopwatch to record the time taken for the skin to recover its normal colour after a blanching pressure is applied. This method is highly subjective and observer-dependent. This paper presents a new, integrated optical sensor probe, combining monitoring of the capillary refilling process with the blanching pressure applied. The sensor consists of an optical fibre-based reflectance photoplethysmography (PPG) sensor to measure the reflected light signal, as well as a fibre Bragg grating (FBG) to measure the applied blanching pressure and to indicate the time when pressure is released. This sensor was applied to calculate the CRT (1.38 ± 0.66 s) of 10 healthy adult volunteers with (55.2 ± 21.8 kPa) blanching pressures. The form of the capillary refilling data was investigated by fitting using an exponential regression model (R2 > 0.96). The integrated probe has the potential to improve the reliability of CRT measurements by standardising the optimum duration and magnitude of the pressure.

scholarly journals Optical Fibre Sensor for Capillary Refill Time and Contact Pressure Measurements under the Foot

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6072
Author(s):  
Hattan K. Ballaji ◽  
Ricardo Correia ◽  
Chong Liu ◽  
Serhiy Korposh ◽  
Barrie R. Hayes-Gill ◽  
...  
Keyword(s):  
Contact Pressure ◽  
Blood Volume ◽  
Optical Fibre ◽  
Fibre Bragg Grating ◽  
Capillary Refill Time ◽  
Volume Changes ◽  
Capillary Refill ◽  
Optical Fibre Sensor ◽  
Skin Contact ◽  
Fibre Sensor

Capillary refill time (CRT) refers to the time taken for body tissue to regain its colour after an applied blanching pressure is released. Usually, pressure is manually applied and not measured. Upon release of pressure, simple mental counting is typically used to estimate how long it takes for the skin to regain its colour. However, this method is subjective and can provide inaccurate readings due to human error. CRT is often used to assess shock and hydration but also has the potential to assess peripheral arterial disease which can result in tissue breakdown, foot ulcers and ultimately amputation, especially in people with diabetes. The aim of this study was to design an optical fibre sensor to simultaneously detect blood volume changes and the contact pressure applied to the foot. The CRT probe combines two sensors: a plastic optical fibre (POF) based on photoplethysmography (PPG) to measure blood volume changes and a fibre Bragg grating to measure skin contact pressure. The results from 10 healthy volunteers demonstrate that the blanching pressure on the subject’s first metatarsal head of the foot was 100.8 ± 4.8 kPa (mean and standard deviation), the average CRT was 1.37 ± 0.46 s and the time to achieve a stable blood volume was 4.77 ± 1.57 s. For individual volunteers, the fastest CRT measured was 0.82 ± 0.11 and the slowest 1.94 ± 0.49 s. The combined sensor and curve fitting process has the potential to provide increased reliability and accuracy for CRT measurement of the foot in diabetic foot ulcer clinics and in the community.

scholarly journals Evaluation of optical fibre sensors in the electrical domain

2020 ◽  
Vol 9 (2) ◽  
pp. 199-208
Author(s):  
Ulrich Nordmeyer ◽  
Niels Neumann ◽  
Xiaozhou Wang ◽  
Dirk Plettemeier ◽  
Torsten Thiel ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Optical Fibre ◽  
Electromagnetic Interference ◽  
Evaluation Method ◽  
Bragg Grating ◽  
Fibre Bragg Grating ◽  
Optical Fibre Sensors ◽  
Novel Approach ◽  
Reflected Light ◽  
Wide Range

Abstract. Optical fibre sensors cover a wide range of applications. They offer versatile advantages including resilience to electromagnetic interference, biocompatibility and chemical resistivity. Even in environments with restricted accessibility, integration difficulties can be overcome by using radio-over-fibre (RoF) technology that allows a wireless read-out. Conventionally, optical fibre sensors are evaluated in the optical domain by analysing the amplitude or spectrum of either the transmitted or the reflected light. A novel approach is to feed a radio frequency-modulated laser into the optical sensor and carry out a full electrical analysis of the resulting radio frequency (RF) signal, which is changed by the sensor's characteristics. This method will be investigated in this paper for fibre Bragg grating-based and chirped fibre Bragg grating-based sensors in reflection and transmission configuration. Their applicability for this new evaluation scheme will be discussed. Subsequent studies may cover additional types of sensors and the testing of the novel evaluation method within an application-related scenario, including packaging.

scholarly journals Stretchable optical fibre sensor for soft surgical robot shape reconstruction

2021 ◽  
Vol 51 (4) ◽  
Author(s):  
Yanlin He ◽  
Likun Gao ◽  
Yuchen Bai ◽  
Hangwei Zhu ◽  
Guangkai Sun ◽  
...  
Keyword(s):  
Optical Fibre ◽  
Soft Materials ◽  
Maximum Error ◽  
Shape Reconstruction ◽  
Fibre Bragg Grating ◽  
Soft Robot ◽  
Soft Robots ◽  
Optical Fibre Sensor ◽  
Fibre Sensor ◽  
Shape Sensing

Soft robotics presents several advantages in the field of minimally invasive surgery. However, existing methods have not fully addressed problems related to soft robot shape sensing due to the complex motion of soft robots and the stretchable nature of the soft materials employed. This study demonstrates the shape sensing of a soft robot with a helically embedded stretchable fibre Bragg grating (FBG)-based optical fibre sensor. Unlike straight FBG embedding configurations, this unique helical configuration prevents sensor dislocation, supports material stretchability, and facilitates shape detection for various soft-robot movements. The proposed soft-robot design principle and FBG sensor are analysed and their fabrication process, which includes an FBG-written optical fibre sensor, is described. Bending experiments are conducted with the soft robot, the wavelengths of FBG sensors at different bending and telescopic movement states are obtained, and the soft-robot shape is reconstructed. Experimental results demonstrate that the maximum error between FBG sensing and the actual bending state is less than 2.5%, validating the feasibility and effectiveness of the proposed helical stretchable FBG sensing method for the shape measurement of soft robots. These results indicate the potential and applicability of this shape-sensing approach in biomedical research.

scholarly journals High temperature high sensitivity optical fibre sensor based on multimode fibre Bragg grating

2018 ◽  
Vol 13 (11) ◽  
pp. 1537-1541
Author(s):  
Qijing Lin ◽  
Na Zhao ◽  
Weile Jiang ◽  
Kun Yao ◽  
Bian Tian ◽  
...  
Keyword(s):  
High Temperature ◽  
Optical Fibre ◽  
High Sensitivity ◽  
Bragg Grating ◽  
Fibre Bragg Grating ◽  
Optical Fibre Sensor ◽  
Fibre Sensor

Effect of acupuncture on capillary refill time in healthy adults: A clinical study

2021 ◽  
Vol 135 ◽  
pp. 104135
Author(s):  
Bo-Yan Yeh ◽  
Yen-Lin Chao ◽  
Yu-Sheng Chen ◽  
Huang-Ping Yu
Keyword(s):  
Clinical Study ◽  
Healthy Adults ◽  
Capillary Refill Time ◽  
Capillary Refill

scholarly journals Optical fibre based real-time measurements during an LDR prostate brachytherapy implant simulation: using a 3D printed anthropomorphic phantom

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
P. Woulfe ◽  
F. J. Sullivan ◽  
L. Byrne ◽  
A. J. Doyle ◽  
W. Kam ◽  
...  
Keyword(s):  
Optical Fibre ◽  
Planning System ◽  
Treatment Planning System ◽  
Prostate Brachytherapy ◽  
Anthropomorphic Phantom ◽  
Optical Fibre Sensor ◽  
Ldr Brachytherapy ◽  
3D Printed ◽  
Average Activity ◽  
Iodine 125

AbstractAn optical fibre sensor based on radioluminescence, using the scintillation material terbium doped gadolinium oxysulphide (Gd2O2S:Tb) is evaluated, using a 3D printed anthropomorphic phantom for applications in low dose-rate (LDR) prostate brachytherapy. The scintillation material is embedded in a 700 µm diameter cavity within a 1 mm plastic optical fibre that is fixed within a brachytherapy needle. The high spatial resolution dosimeter is used to measure the dose contribution from Iodine-125 (I-125) seeds. Initially, the effects of sterilisation on the sensors (1) repeatability, (2) response as a function of angle, and (3) response as a function of distance, are evaluated in a custom polymethyl methacrylate phantom. Results obtained in this study demonstrate that the output response of the sensor, pre- and post-sterilisation are within the acceptable measurement uncertainty ranging from a maximum standard deviation of 4.7% pre and 5.5% post respectively, indicating that the low temperature sterilisation process does not damage the sensor or reduce performance. Subsequently, an LDR brachytherapy plan reconstructed using the VariSeed treatment planning system, in an anthropomorphic 3D printed training phantom, was used to assess the suitability of the sensor for applications in LDR brachytherapy. This phantom was printed based on patient anatomy, with the volume and dimensions of the prostate designed to represent that of the patient. I-125 brachytherapy seeds, with an average activity of 0.410 mCi, were implanted into the prostate phantom under trans-rectal ultrasound guidance; following the same techniques as employed in clinical practice by an experienced radiation oncologist. This work has demonstrated that this sensor is capable of accurately identifying when radioactive I-125 sources are introduced into the prostate via a brachytherapy needle.

scholarly journals Effects of capillary refill time-vs. lactate-targeted fluid resuscitation on regional, microcirculatory and hypoxia-related perfusion parameters in septic shock: a randomized controlled trial

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Ricardo Castro ◽  
Eduardo Kattan ◽  
Giorgio Ferri ◽  
Ronald Pairumani ◽  
Emilio Daniel Valenzuela ◽  
...  
Keyword(s):  
Septic Shock ◽  
Randomized Controlled Trial ◽  
Fluid Resuscitation ◽  
Controlled Trial ◽  
Tissue Perfusion ◽  
Capillary Refill Time ◽  
Capillary Refill ◽  
Randomized Controlled ◽  
Microcirculatory Flow ◽  
The Impact

Abstract Background Persistent hyperlactatemia has been considered as a signal of tissue hypoperfusion in septic shock patients, but multiple non-hypoperfusion-related pathogenic mechanisms could be involved. Therefore, pursuing lactate normalization may lead to the risk of fluid overload. Peripheral perfusion, assessed by the capillary refill time (CRT), could be an effective alternative resuscitation target as recently demonstrated by the ANDROMEDA-SHOCK trial. We designed the present randomized controlled trial to address the impact of a CRT-targeted (CRT-T) vs. a lactate-targeted (LAC-T) fluid resuscitation strategy on fluid balances within 24 h of septic shock diagnosis. In addition, we compared the effects of both strategies on organ dysfunction, regional and microcirculatory flow, and tissue hypoxia surrogates. Results Forty-two fluid-responsive septic shock patients were randomized into CRT-T or LAC-T groups. Fluids were administered until target achievement during the 6 h intervention period, or until safety criteria were met. CRT-T was aimed at CRT normalization (≤ 3 s), whereas in LAC-T the goal was lactate normalization (≤ 2 mmol/L) or a 20% decrease every 2 h. Multimodal perfusion monitoring included sublingual microcirculatory assessment; plasma-disappearance rate of indocyanine green; muscle oxygen saturation; central venous-arterial pCO2 gradient/ arterial-venous O2 content difference ratio; and lactate/pyruvate ratio. There was no difference between CRT-T vs. LAC-T in 6 h-fluid boluses (875 [375–2625] vs. 1500 [1000–2000], p = 0.3), or balances (982[249–2833] vs. 15,800 [740–6587, p = 0.2]). CRT-T was associated with a higher achievement of the predefined perfusion target (62 vs. 24, p = 0.03). No significant differences in perfusion-related variables or hypoxia surrogates were observed. Conclusions CRT-targeted fluid resuscitation was not superior to a lactate-targeted one on fluid administration or balances. However, it was associated with comparable effects on regional and microcirculatory flow parameters and hypoxia surrogates, and a faster achievement of the predefined resuscitation target. Our data suggest that stopping fluids in patients with CRT ≤ 3 s appears as safe in terms of tissue perfusion. Clinical Trials: ClinicalTrials.gov Identifier: NCT03762005 (Retrospectively registered on December 3rd 2018)

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