Anesthesia Depth Monitoring Based on Anesthesia Monitor with the Help of Artificial Intelligence / 中国医疗器械杂志

OBJECTIVE@#To use the low-cost anesthesia monitor for realizing anesthesia depth monitoring, effectively assist anesthesiologists in diagnosis and reduce the cost of anesthesia operation.@*METHODS@#Propose a monitoring method of anesthesia depth based on artificial intelligence. The monitoring method is designed based on convolutional neural network (CNN) and long and short-term memory (LSTM) network. The input data of the model include electrocardiogram (ECG) and pulse wave photoplethysmography (PPG) recorded in the anesthesia monitor, as well as heart rate variability (HRV) calculated from ECG, The output of the model is in three states of anesthesia induction, anesthesia maintenance and anesthesia awakening.@*RESULTS@#The accuracy of anesthesia depth monitoring model under transfer learning is 94.1%, which is better than all comparison methods.@*CONCLUSIONS@#The accuracy of this study meets the needs of perioperative anesthesia depth monitoring and the study reduces the operation cost.

Heart rate extraction algorithm based on adaptive heart rate search model / 生物医学工程学杂志

Photoplethysmography (PPG) is a non-invasive technique to measure heart rate at a lower cost, and it has been recently widely used in smart wearable devices. However, as PPG is easily affected by noises under high-intensity movement, the measured heart rate in sports has low precision. To tackle the problem, this paper proposed a heart rate extraction algorithm based on self-adaptive heart rate separation model. The algorithm firstly preprocessed acceleration and PPG signals, from which cadence and heart rate history were extracted respectively. A self-adaptive model was made based on the connection between the extracted information and current heart rate, and to output possible domain of the heart rate accordingly. The algorithm proposed in this article removed the interference from strong noises by narrowing the domain of real heart rate. From experimental results on the PPG dataset used in 2015 IEEE Signal Processing Cup, the average absolute error on 12 training sets was 1.12 beat per minute (bpm) (Pearson correlation coefficient: 0.996; consistency error: -0.184 bpm). The average absolute error on 10 testing sets was 3.19 bpm (Pearson correlation coefficient: 0.990; consistency error: 1.327 bpm). From experimental results, the algorithm proposed in this paper can effectively extract heart rate information under noises and has the potential to be put in usage in smart wearable devices.

La relación de la edad con los componentes espectrales de las realizaciones sin ruido de señales fotopletismográficas: resultados de un enfoque de identificación no lineal / Relationship of Age with Spectral Components of Noise-Free Realizations of Photoplethysmographic Signals: Outcomes of a Nonlinear Identification Approach

Background: Age-related changes in the vascular network have been widely documented, however, nonlinear identification has been poorly applied to the analysis of cardiovascular signals. Objective: To determine the impact of age on spectral components of Noise-free realizations (NFR) obtained from photoplethysmographic signals, summarized in the Kernel Complexity Regressive Index (KCRIndex). Methods: With 190 apparently healthy participants (9 to 89 years) from Orense, Spain, Photoplethysmographic signals were recorded during 5 minutes in supine position using Nellcor-395 pulse oximeter; signals were digitized at 1000 Hz, and furtherly submitted to nonlinear identification via a kernel nonlinear autoregressive estimator. KCRIndex is defined as the average of at least three negative slope values at the NFR log-log spectrum in the 9 to 25 Hz frequency region. Results: KCRIndex decreased with age in a linear fashion and did not differ between genders. The regression line obtained was KCRIndex=-0.025*age+6.868 (r=-0.751). Conclusions: KCRIndex, is strongly correlated with age, thus opening up new possibilities for cardiovascular exploration at primary health care settings and even on open field conditions(AU)

Antecedentes: los cambios relacionados con la edad en la red vascular se han documentado ampliamente, sin embargo, la identificación no lineal solo se ha aplicado de manera esporádica al análisis de las señales cardiovasculares. Objetivo: determinar los cambios con la edad en los componentes espectrales de las realizaciones sin ruido (NFR) obtenidas a partir de señales fotopletismográficas, resumidas en el índice regresivo de la complejidad por núcleos (KCRIndex). Métodos: Con 190 participantes aparentemente sanos (de 9 a 89 años) residentes en Orense, España, se registraron señales fotopletismográficas durante 5 minutos en posición supina usando un oxímetro de pulso Nellcor-395; las señales se digitalizaron a 1000 Hz, y se sometieron a identificación no lineal a través de un estimador autorregresivo no lineal por núcleos. El KCRIndex se define como el promedio de al menos tres valores de pendiente negativos en el espectro log-log de NFR en la región de frecuencia de 9 a 25 Hz. Resultados: KCRIndex disminuyó con la edad de forma lineal y no difirió entre géneros. La línea de regresión obtenida fue KCRIndex = -0.025 * edad + 6.868 (r = -0.751). Conclusiones: Este índice propuesto está fuertemente correlacionado con la edad, lo que abre nuevas posibilidades para la exploración cardiovascular en entornos de atención primaria de salud e incluso en condiciones de campo(AU)

Area Triangulation Method for Automatic Detection of Venous Emptying Maneuvers

Abstract Venous refilling time (VRT) can diagnose the presence of venous diseases in lower limbs. In order to calculate VRT it is necessary to determine the End of the Emptying Maneuvers (EEM). First Derivative Method (FDM) can be employed for automatic detection of the EEM, but its sensitivity to artifacts and noise can degrade its performance. In contrast, studies report that Area Triangulation Method (ATM) evinces effectiveness in biosignals point finding. This work compares the exactness of ATM and FDM for recognition of the EEM. The annotations made by 3 trained human observers on 37 photoplethysmography records were used as a reference. Bland-Altman graphics supported the analysis of agreement among human observers and methods, which was complemented with Analysis of variance and Multiple Comparisons statistical tests. Results showed that ATM is more accurate than FDM for automatic detection of the EEM, with statistically significant differences (p-value < 0.01).

Comparação do índice tornozelo-braquial com parâmetros de rigidez e resistência arterial periférica avaliados por fotopletismografia em idosos / Comparison of the ankle-brachial index with parameters of stiffness and peripheral arterial resistance assessed by photoplethysmography in elderly patients

O índice tornozelo-braquial (ITB) utiliza a razão entre a pressão arterial sistólica do tornozelo e do braço para diagnosticar de forma não invasiva a doença arterial periférica (DAP). A fotopletismografia (photoplethysmography, PPG) faz a medição e o registro das modificações de volume sanguíneo do corpo humano por meio de técnicas ópticas. Objetivos O objetivo deste estudo foi comparar o ITB com parâmetros de rigidez arterial e resistência periférica avaliados pela PPG em idosos e propor um modelo de predição para o ITB. Métodos Foi realizado um estudo transversal quantitativo. A amostra foi composta por idosos atendidos no ambulatório médico de especialidades da Universidade do Sul de Santa Catarina (UNISUL). Foram verificados: idade, sexo, índice de massa corporal (IMC), presença de comorbidades, tabagismo e atividade física. Para comparação das variáveis obtidas com a PPG com o ITB, foi realizada regressão linear bivariada e multivariada, considerando erro α = 0,05. Resultados Foram avaliados 93 idosos, sendo 63,4% mulheres. Em 98,9% dos casos, o ITB apresentou-se dentro da normalidade. Na comparação do ITB e variáveis derivadas da PPG em relação à idade, foram demonstradas associações significativas. Contudo, não foram observadas associações significativas entre ITB e PPG. O modelo multivariado indicou que apenas idade, sexo e tabagismo foram associados ao ITB. Conclusões Como conclusão, o ITB e a PPG demonstraram associação com o envelhecimento arterial, tendo em vista sua correlação com a idade; contudo, o ITB foi relacionado apenas com idade, sexo e tabagismo. Mais estudos são necessários para avaliar o potencial uso da PPG como rastreio de doenças vasculares em rotinas ambulatórias

The ankle-brachial index (ABI) uses the ratio between systolic blood pressures at the ankle and the arm to diagnose peripheral arterial disease (PAD) noninvasively. Photoplethysmography (PPG) measures and records changes to the blood volume in the human body using optical techniques. Objectives The objective of this study was to compare ABI with arterial stiffness and peripheral resistance parameters assessed using PPG in elderly patients and to propose a model for prediction of ABI. Methods A cross-sectional, quantitative study was conducted. The sample comprised elderly patients seen at a medical specialties clinic at the Universidade do Sul de Santa Catarina (UNISUL), Brazil. Age, sex, body mass index (BMI), comorbidities, smoking, and physical activity were recorded. The variables obtained using PPG and ABI were compared using bivariate and multivariate linear regression, with an α error of 0.05. Results A total of 93 elderly patients were assessed, 63.4% of whom were women. In 98.9% of cases, ABI was within normal limits. Comparison of ABI with variables acquired by PPG revealed significant associations with age. However, no significant associations were observed between ABI and PPG. The multivariate model indicated that only age, sex, and smoking were associated with ABI. Conclusions In conclusion, ABI and PPG exhibited associations with arterial aging, considering its correlation with age. However, ABI was only related to age, sex, and smoking. More studies are needed to evaluate the potential uses of PPG for screening for vascular diseases in ambulatory settings

Aumento en la efectividad de la identificación de cimas y pies en el pulso fotopletismográfico al reconstruirlo mediante filtrado adaptativo / Increase in the effectiveness of identifying peaks and feet of the photoplethysmographic pulse to be reconstructed it using adaptive filtering

Resumen: Objetivo: Mejorar la identificación de cimas y pies en el pulso fotopletismográfico (PPG, por sus siglas en inglés), deformado por efecto del ruido miocinético, mediante la implementación de un dedal modificado y filtrado adaptativo. Método: Se obtuvo el PPG en 10 voluntarios sanos empleando 2 sistemas de fotopletismografía colocados en el dedo índice de cada mano, y registrándolos simultáneamente durante 3 min. Durante el primer minuto de registro, ambas manos estuvieron en reposo, y durante los 2 min posteriores, solo la mano izquierda realizó movimientos cuasi-periódicos para añadir ruido miocinético. Se emplearon 2 metodologías para procesar las señales fuera de línea, en una se usó un filtro con el algoritmo de mínimos cuadrados promediados (LMS, por sus siglas en inglés) y en la otra se hizo un preprocesamiento adicional al filtrado LMS. Ambas metodologías fueron comparadas y la de menor error porcentual en la señal recuperada se utilizó para valorar la mejora en la identificación de cimas y pies del PPG. Resultados: El error promedio obtenido fue del 22.94% para la primera metodología, y del 3.72% para la segunda. Los errores en la identificación de cimas y pies antes de filtrar el PPG fueron del 24.26 y 48.39%, respectivamente, una vez filtrados, disminuyeron a 2.02 y 3.77%, respectivamente. Conclusiones: El filtrado adaptativo basado en el algoritmo LMS, más una etapa de preprocesamiento, permite atenuar el ruido miocinético en el PPG, y aumentar la efectividad en la identificación de cimas y pies de pulso, que resultan de gran importancia para una valoración médica.

Abstract: Objective: To improve the identification of peaks and feet in photoplethysmographic (PPG) pulses deformed by myokinetic noise, through the implementation of a modified fingertip and applying adaptive filtering. Method: PPG signals were recordedfrom 10 healthy volunteers using two photoplethysmography systems placed on the index finger of each hand. Recordings lasted three minutes andwere done as follows: during the first minute, both handswere at rest, and for the lasting two minutes only the left hand was allowed to make quasi-periodicmovementsin order to add myokinetic noise. Two methodologies were employed to process the signals off-line. One consisted on using an adaptive filter based onthe Least Mean Square (LMS) algorithm, and the other includeda preprocessing stage in addition to the same LMS filter. Both filtering methods were compared and the one with the lowest error was chosen to assess the improvement in the identification of peaks and feet from PPG pulses. Results: Average percentage errorsobtained wereof 22.94% with the first filtering methodology, and 3.72% withthe second one. On identifying peaks and feet from PPG pulsesbefore filtering, error percentages obtained were of 24.26% and 48.39%, respectively, and once filtered error percentageslowered to 2.02% for peaks and 3.77% for feet. Conclusions: The attenuation of myokinetic noise in PPG pulses through LMS filtering, plusa preprocessing stage, allows increasingthe effectiveness onthe identification of peaks and feet from PPG pulses, which are of great importance for medical assessment.

Evaluation of quality of life and photoplethysmography in patients with chronic venous insufficiency treated with foam sclerotherapy

BACKGROUND: Ultrasound-guided foam sclerotherapy plays a major role in treatment of chronic venous insufficiency, providing clinical and hemodynamic improvement to patients undergoing treatment.OBJECTIVES: To examine the relationships between venous refilling time and impact of venous disease on quality of life and between changes in venous refilling time and improvement of symptoms after ultrasound-guided foam sclerotherapy for chronic venous insufficiency. METHODS: Thirty-two patients classified as C4, C5 or C6 answered a questionnaire on quality of life and symptoms and their venous filling time was measured using photoplethysmography before and 45 days after treatment of chronic venous insufficiency with ultrasound-guided foam sclerotherapy.RESULTS: Statistically significant improvements were observed in quality of life scores and in venous filling time and in the following symptoms: aching, heavy legs, restless legs, swelling, burning sensations, and throbbing (p<0.0001). A similar improvement was also seen in the work and social domains of quality of life (p<0.0001).CONCLUSIONS: As confirmed by questionnaire scores and venous refilling times, ultrasound-guided foam sclerotherapy demonstrated efficacy and resulted in high satisfaction levels and low rates of major complications.

CONTEXTO: A escleroterapia com espuma guiada por ultrassom (EGUS) ocupa lugar de destaque no tratamento da insuficiência venosa crônica (IVC), proporcionando melhora clínica e hemodinâmica aos pacientes submetidos ao tratamento.OBJETIVOS: Verificar a correlação entre dados obtidos por questionário de qualidade de vida e de sintomas com dados obtidos por fotopletismografia (FPG), antes e depois do tratamento por escleroterapia com espuma guiada por ultrassom (EGUS) da insuficiência venosa crônica (IVC). MÉTODOS: Um grupo de 32 pacientes, classificados como C4, C5 e C6, foi submetido à aplicação de questionário de qualidade de vida e sintomas, sendo aferido o tempo de enchimento venoso (TEV) por FPG antes e 45 dias depois do tratamento da IVC através de EGUS. O teste do sinal foi utilizado para análise estatística da melhora dos escores dos questionários e do TEV. O teste de McNemar foi utilizado para avaliação da melhora nos sintomas e do impacto do tratamento nas atividades laborais e sociais dos pacientes.RESULTADOS: Houve melhora nos escores dos questionários de qualidade de vida e no TEV, com significância estatística (p<0,0001). Houve melhora estatisticamente significativa nos sintomas: dor, cansaço, edema, queimação, pernas inquietas e latejamento (p<0,0001). Incremento na qualidade laboral e social após o tratamento apresentou melhora estatisticamente significativa (p<0,0001). Não ocorreram complicações maiores ou efeitos adversos nesta série.CONCLUSÕES: A EGUS mostrou-se eficaz, com alto índice de satisfação e baixas taxas de complicacões maiores, ratificada pelos escores dos questionários e pelos TEVs aferidos pela FPG.

Applying the 3-element windkessel model to photoplethysmographic signals. Gender differences and age correlation

Automatically averaged photoplethysmographic (PPG) signals were fit to a 3-element windkessel model using a Gauss-Newton optimization algorithm. Data corresponded to 78 healthy subjects (ages from 8 to 87 years). Unlike other reports, two phase velocities are also estimated from the model. Gender differences were found, particularly respect to individual parameters correlation with age. When a nonlinear model was fit to the two first principal components, a high correlation with age was found for both females (r=0.69) and male subjects (r=0.77). Our results further support the idea that the PPG signal is a valuable source of information about the cardiovascular system, comparable to the much more expensive continuous pressure signal(AU)

Señales fotopletismográficas automáticamente promediadas fueron ajustadas a un modelo de bomba hidráulica de tres elementos. Para ello se utilizó un algoritmo de optimización del tipio Gauss-Newton. Los datos fueron obtenidos de 78 individuos sanos con edades entre 8 y 87 años. A diferencia de otros reportes, en el presente trabajo se estimaron dos velocidades de fase a partir del modelo. Al aplicar un modelo no lineal respecto los dos primeros componentes principales, se obtuvo una elevada correlación con la edad tanto para los sujetos femeninos (r=0.69) como para los masculinos (r=0.77). Nuestros resultados ofrecen un apoyo adicional a la idea de que la señal fotopletismográfica es una fuente importante de información acerca del sistema cardiovascular, comparable a la señal de presión continua, aun cuando esta última es mucho más costosa(AU)

Avaliação quantitativa da insuficiência da veia safena magna nos pacientes portadores de varizes primárias de membros inferiores pelo mapeamento dúplex e fotopletismografia / Quantitative evaluation of the insufficiency of the great saphenous vein of patients with primary varicose veins of the lower limbs by means of duplex scanning and photoplethysmography

INTRODUÇÃO: A doença venosa crônica (DVC) é uma doença comum com conseqüências sócio-econômicas importantes. O refluxo é uma das principais causas da DVC. Detectar e quantificar o refluxo são medidas importantes no diagnóstico de insuficiência venosa crônica. A avaliação quantitativa da DVC pode ser realizada por meio de métodos invasivos e não invasivos. Os métodos não invasivos, quantitativos, são: fotopletismografia (FPG), pletismografia a ar e o mapeamento dúplex. O MD, padrão-ouro, permite a detecção e quantificação acurada do refluxo em veias individuais, pela medida da duração do refluxo ou tempo de fechamento da válvula, além de proporcionar informações anatômicas e funcionais relevantes para direcionar o tratamento de veias varicosas. Nos pacientes com varizes primárias dos membros inferiores a veia safena magna (VSM) é freqüentemente acometida, especialmente por refluxo na junção safeno-femoral (JSF), por insuficiência da válvula ostial. A avaliação da VSM é importante porque a sua preservação traz vantagens, pois a mesma tem sido utilizada como substituto arterial em doenças degenerativas, como a doença arterial obstrutiva crônica dos membros inferiores, na revascularização miocárdica e nos traumas vasculares de extremidades...

INTRODUCTION: The chronic venous disease (CVD) is a common disease with socio-economic consequences. Reflux is one of the main causes of CVD. Detecting and quantifying the reflux are important steps in the diagnosis of chronic venous insufficiency. The quantitative evaluation of CVD may be performed by means of invasive and non-invasive methods. Non-invasive quantitative methods are: photoplethysmography (FPG), air plethysmography and duplex scan. The DS, gold standard, allows the detection and quantification accurate measurement of the vein reflux individual, by the measure of length of reflux or time of valve closure, in addition to providing functional and relevant anatomical information to guide the treatment of varicose veins. In patients with primary varicose veins of the lower limbs the great saphenous vein (GSV) is frequently affected, especially by reflux in the saphenofemoral junction (SFJ), because of the failure of the ostial valve. The evaluation of the GSV is important because its preservation brings advantages so that it has been used as a replacing arterial in degenerative diseases such as chronic obstructive arterial disease of the lower limbs, in myocardial revascularization and in vascular trauma of the extremities...

Non-Invasive Estimation of Systolic Blood Pressure and Diastolic Blood Pressure Using Photoplethysmograph Components

PURPOSE: Photoplethysmography (PPG) is a noninvasive optical technology that detects changes in blood volume in the vascular system. This study aimed to investigate the possibilities of monitoring the cardiovascular system status by using PPG. MATERIALS AND METHODS: Forced hemodynamic changes were induced using cardiac stimulants; dopamine and epinephrine, and PPG components were recorded by a noninvasive method at the peripheral blood vessels. The results were compared among 6 dogs. Endotracheal intubation was performed after an intramuscular injection of 25 mg/kg ketamine sulfate, and anesthesia was maintained with 2% enflurane. After stabilizing the animals for 15 min, 16 mg/mL diluted dopamine was injected into a vein for 2 min at 20 microgram/kg.min(-1) by using an infusion pump. Thereafter, the infusion pump was stopped, and 1 mg epinephrine was injected intravenously. Fluid administration was controlled to minimize preload change in blood pressure. RESULTS: After stimulant administration, systolic blood pressure (SBP) and diastolic blood pressures (DBP) increased. The direct current (DC) component, which reflects changes in blood volume, decreased while the alternating current (AC) component, which reflects changes in vascular compliance and resistance, increased. The correlation coefficient between SBP and the foot of the DC component was 0.939 (p < 0.01), while it was 0.942 (p < 0.01) for DBP and the peak of the DC component. The AC component could predict the increase in vascular resistance from a stable pulse blood volume, even with increased pulse pressure. Conclusions: These results support the possibility that PPG components may be used for easy and noninvasive measurement of hemodynamic changes in the cardiovascular system.

Evaluación cualitativa de la morfología de la señal fotopletismográfica en el diagnóstico de la insuficiencia arterial / Qualitative evaluation of the morphology of the photopletismographic signal in the diagnosis of arterial insufficiency

Con el objetivo de evaluar las posibilidades de un análisis cualitativo simple de la curva fotopletismográfica AC para diagnosticar la insuficiencia arterial de miembros inferiores, se compararon los registros obtenidos en las extremidades de 289 pacientes diabéticos y 571 no diabéticos con los valores de índice tobillo/brazo realizado por método Doppler. Las señales fotopletismográficas fueron clasificadas en función de las características siguientes: presencia de señal, asimetría de la misma, características de la fase descenso y presencia de dicrotismo. Como regla de oro, se empleó el índice tobillo/brazo, y se consideró como normales los valores mayores o iguales que 0,9. Se encontraron valores de exactitud, sensibilidad y especificidad de 90,8 por ciento, 92 por ciento y 90 por ciento respectivamente para los pacientes no diabéticos. Los pacientes diabéticos, por su parte, mostraron valores de exactitud, sensibilidad y especificidad de 90 por ciento, 85 por ciento y 93 por ciento respectivamente. Se concluye que el análisis propuesto puede ser útil en el diagnóstico de la insuficiencia arterial.

Aimed at evaluating the possibilities of a simple qualitative analysis of the photopletismographic curve AC for diagnosing the arterial insufficiency of the lower limbs, the registers obtained in the extremities of 289 diabetic patients and 571 non diabetic were compared with the values of the ankle/arm index obtained by Doppler method. The photopletismographic signals were classified according to the following characteristics: presence of signal, asymmetry of it, characteristics of the decrease phase and presence of dicrotism. The ankle/arm index was used as a gold standard and those values higher than or equal to 0.9 were considered normal. Values of exactness, sensitivity and specificity of 90.8 percent, 92 percent y 90 percent, respectively, were found for the non diabetic patients. On the other hand, the diabetic patients showed values of exactness, sensitivity and specificity of 90 percent, 85 percent and 93 percent, respectively. It was concluded that the analysis proposed may be useful in the diagnosis of arterial insufficiency.