Oximetría de pulso y toma de decisión

Introducción: La enfermad producida por el COVID-19 constituye un problema sanitario mundial. La identificación precoz de las manifestaciones clínicas y del compromiso respiratorio resulta vital para minimizar las complicaciones de la enfermedad; en este sentido, la utilización del oxímetro de pulso constituye una alternativa interesante. Objetivo: Describir las ventajas aportadas por la utilización del oxímetro de pulso en la toma de decisión de pacientes para acudir oportunamente a solicitar atención médica. Métodos: Investigación básica, diseño descriptivo y retrospectivo. Universo constituido por 348 pacientes con diagnóstico de COVID-19 y la muestra por 184 casos. Se determinó frecuencia de complicaciones e influencia del uso de oxímetro de pulso en la toma de decisiones. Se utilizó prueba no paramétrica de Odd Ratio y Fisher exacta para identificar rango de ocurrencia. Resultados: promedio de edad de 54,47 años con predominio de pacientes femeninas (60,33 %) y con comorbilidades asociadas (66,85 %). El 25,00 % de los pacientes presentó afectación respiratoria como complicación de la OVID-19. El 47,83 % de los pacientes con complicaciones uso oxímetro de pulso, aunque solo el 27,27 % acudió tempranamente a consulta, pero si en el 90,91 % la decisión de asistir a servicio de urgencia estuvo influenciada por el uso del oxímetro de punto y sus resultados. Conclusiones: La oximetría de pulso ayudó a los pacientes a tomar la decisión de acudir en busca de atención médica. Puede considerarse el monitoreo de la saturación de oxígeno como una acción positiva en torno a la sospecha clínica de afección respiratoria severa.

Introduction: The disease caused by COVID-19 constitutes a global health problem. The early identification of clinical manifestations and respiratory compromise is vital to minimize the complications of the disease; in this sense, the use of the pulse oximeter constitutes an interesting alternative. Objective: To describe the advantages provided by the use of the pulse oximeter in the decision-making of patients to go in a timely manner to request medical attention. Methods: Basic research, descriptive and retrospective design. Universe made up of 348 patients diagnosed with COVID-19 and the sample of 184 cases. The frequency of complications and the influence of the use of pulse oximeter in decision making were determined. Non-parametric Odd Ratio and Fisher's exact tests were used to identify the range of occurrence. Results: average age of 54.47 years with a predominance of female patients (60.33 %) and with associated comorbidities (66.85 %). 25.00 % of the patients presented respiratory involvement as a complication of OVID-19. 47.83 % of the patients with complications used a pulse oximeter, although only 27.27 % attended the consultation early, but in 90.91 % the decision to attend the emergency service was influenced by the use of the oximeter point and its results. Conclusions: Pulse oximetry helped patients make the decision to seek medical attention. Oxygen saturation monitoring can be considered as a positive action around the clinical suspicion of severe respiratory disease.

“Oxygen Pheriwala: ” An Innovative Model for SARS-CoV-2 Screening in Resource-Limited Settings

The second wave of SARS?CoV?2 infection came as a hypoxic emergency and situation became worse in rural India, where undiagnosed COVID-19 patients died without any diagnosis or intervention. The primary aim of this innovative model was the early diagnosis of suspected SARS?CoV?2 cases, providing empirical treatment and timely referral to appropriate COVID care facilities. Fever was measured with infrared thermometer and oxygen saturation level with pulse oximeter. A total of 8203 people were screened, of which 274 persons were febrile and 69 (25%) were hypoxic too. Sixty?four out of 69 (93%) patients turned COVID?19 positive on reverse transcription?polymerase chain reaction. At the end of 3 weeks, 48/64 (75%) patients were successfully discharged. This model can be easily implemented in resource?limited regions to identify and prioritize the patients not only in this pandemic but also in outbreak of other communicable diseases.

Medición de los niveles de lactato sérico y frecuencia cardiaca en caninos (Canis lupus familiaris) braquicefálicos, mesocefálicos y dolicocefálicos sometidos a prueba de esfuerzo en trotadora motorizada / Measurement of serum lactate levels and heart rate in canines (Canis lupus familiaris) Brachycephalic, Mesocephalic and Dolichocephalic submitted to a stress test on a motorized treadmill

RESUMEN Se analizaron los niveles de lactato sérico y de frecuencia cardiaca (FC) en 15 perros clinicamente sanos que fueron sometidos a pruebas de esfuerzo en trotadora motorizada, buscando verificar un grado de fatiga muscular frente a una prueba de esfuerzo intenso. Se consideraron pacientes con morfologia craneana de tipo braquicefálico, mesocefálico y dolicocefálico. Las mediciones séricas de lactato fueron conseguidas por medio de un medidor portátil, mientras que las frecuencias cardiacas se obtuvieron a través de un oximetro portátil a los tiempos 0, 10, 20 y 30 minutos, en los diferentes momentos de esfuerzo fisico en la trotadora motorizada, la cual fue adaptada en su inclinación en 15% y a un máximo de velocidad de 10 km/h. Las medias de los niveles séricos entre perros mesocefálicos y dolicocefálicos fueron significativas, a diferencia de los perros braquicefálicos los cuales resultaron no significativos. Las medias de las frecuencias cardiacas no tuvieron diferencia significativa bajo un 95% de confianza.

ABSTRACT Serum lactate and heart rate (HR) levels were analyzed in 15 clinically healthy dogs that were subjected to stress tests on a motorized treadmill, seeking to verify a degree of muscle fatigue compared to an intense exercise test. Patients with brachycephalic, mesocephalic and dolichocephalic type cranial morphology were considered. Serum lactate measurements were procured by means of a portable meter, while heart rates were obtained through a portable oximeter at the times 0, 10, 20, and 30 minutes at different moments of physical effort on the motorized treadmill, which was adapted in its inclination by 15% and at a maximum speed of 10 km/h. Mean serum levels between mesocephalic and dolichocephalic dogs were significant, unlike brachycephalic dogs, which were not significant. The mean heart rates did not have a significant difference under 95% confidence.

Study on knowledge, attitudes and practices of pulse oximetry among pediatric healthcare providers in China and their influencing factors / 中华实用儿科临床杂志

Objective:To investigate the knowledge, attitudes, and practices (KAP) of pulse oximetry among pediatric healthcare providers in China and analyze the factor influencing the KAP.Methods:A self-developed questionnaire was used for an online research on the KAP of 11 849 pediatric healthcare providers from 31 provinces, autonomous regions, and municipalities of China from March 11 to 14, 2022.The factors influencing the KAP of pulse oximetry among pediatric healthcare providers were examined by Logistic regression. Results:The scores of KAP, of pulse oximetry were 5.57±0.96, 11.24±1.25 and 11.19±4.54, respectively.The corresponding scoring rates were 69.61%, 74.95%, and 55.99%, respectively. Logistic regression results showed that the gender and working years of pediatric healthcare providers, the region they were located, and whether their medical institution was equipped with pulse oximeters were the main factors affecting the knowledge score (all P<0.05). Main factors influencing the attitude score of pediatric healthcare providers included their knowledge score, gender, educational background, working years, region, medical institution level, and whether the medical institution was equipped with pulse oximeters (all P<0.05). For the practice score, the main influencing factors were the knowledge score, gender, age, and whether the medi-cal institution was equipped with pulse oximeters (all P<0.05). Conclusions:Chinese pediatric healthcare providers need to further improve their knowledge about and attitudes towards pulse oximetry.Pulse oximeters are evidently under-used.It is urgent to formulate policies or guidelines, strengthen education and training, improve knowledge and attitudes, equip more institutions with pulse oximeters, and popularize their application in medical institutions.

Community case management of chest indrawing pneumonia in children aged 2 to 59 months by community health workers: study protocol for a multi-country cluster randomized open label non-inferiority trial

Background:The World Health Organization (WHO) integrated management of childhood illness (IMCI) protocol recommends treatment of chest indrawing in 2-59 months old children with oral amoxicillin by trained health facility workers. Whereas, the WHO/UNICEF integrated community case management (iCCM) protocol recommends referral by community level health workers (CLHWs) to a health facility. This study aims to evaluate whether CLHWs can treat chest indrawing pneumonia effectively and safely.Methods:Thismulti-centre cluster randomized controlled open label, non-inferiority trial will be conductedin Bangladesh, Ethiopia, India and Malawi. All sites will use a common protocol with the same study design, participants, intervention, control and outcomes. CLHWs will identify 2-59 months old children with chest indrawing. Study supervisors, trained in the iCCM protocol, will confirm CLHWs’ findings. Pulse oximetry will be used to identify hypoxaemic children. In the intervention group, enrolled children will be treated with oral amoxicillin for 5 days, and in the control group they will be referred to ahealth facility, after providing first dose of oral amoxicillin. An independent outcome assessor will visit each enrolled child on days 6 and 14 of enrolment, to assess study outcomes.Conclusions:If CLHWs can effectively and safely treat chest indrawing pneumonia in 2-59 months old children, it will increase access to pneumonia treatment substantially, as in many settings, health facilities and trained health workers are not easily accessible. Moreover, this evidence will contribute towards the review of the current iCCM protocol and its harmonization with the IMCI protocol. Trial Registration:The trial is registered at AZNCTR International Trial Registry as ACTRN12617000857303

Management of fast breathing pneumonia in young infants aged 7 to 59 days by community level health workers: protocol for a multi-centre cluster randomized controlled trial

Background:WHO does not recommend community-level health workers (CLHWs) using integrated community case management (iCCM) to treat 7-59 days old infants with fast breathing with oral amoxicillin, whereas World Health Organization (WHO)integrated management of childhood illness (IMCI) recommends it. We want to collect evidence to help harmonization of both protocols.Methods:A cluster, randomized, open-label trial will be conducted in Africa and Asia (Ethiopia, Malawi, Bangladesh and India) using a common protocol with the same study design, inclusion criteria, intervention, comparison, and outcomes to contribute to the overall sample size. This trial will also identify hypoxaemia in young infants with fast breathing. CLHWs will assess infants for fast breathing, which will be confirmed by a study supervisor. Enrolled infants in the intervention clusters will be treated with oral amoxicillin, whereas in the control clusters they will be managed as per existing iCCM protocol. An independent outcome assessor will assess all enrolled infants on days 6 and 14 of enrolment for the study outcomes in both intervention and control clusters. Primary outcome will be clinical treatment failure by day 6. This trial will obtain approval from the WHO and site institutional ethics committees. Conclusions: If the research shows that CLHWs can effectively and safely treat fast breathing pneumonia in 7-59 days old young infants, it will increase access to pneumonia treatment substantially for infants living in communities with poor access to health facilities. Additionally, this evidence will contribute towards the review of the current iCCM protocol and its harmonization with IMCI protocol.Trial Registration:The trial is registered at AZNCTR International Trial Registry as ACTRN12617000857303.

Diagnostic accuracy of dental pulse oximeter with customized sensor holder, thermal test and electric pulp test for the evaluation of pulp vitality: an in vivo study / Precisão diagnóstica do oxímetro de pulso odontológico com suporte de sensor personalizado, teste térmico e teste elétrico da polpa para avaliação da vitalidade pulpar: um estudo in vivo

Background: the efficiency of the diagnostic aids plays an important role in the treatment plan. This study aims to assess the diagnostic accuracy of dental pulse oximeter with a customized sensor holder, thermal test and electric pulp tester in assessing the actual pulp status and to evaluate the oxygen saturation level in control healthy teeth, non-vital and teeth with irreversible pulpitis. Material and methods: thirty-seven single canal teeth requiring endodontic therapy were included in the study. The selected teeth were tested with dental pulse oximeter, electric pulp test, cold spray, and heated gutta percha stick. Between each test a time lag of 2 minutes was allowed for the central sensitization to occur. Three blinded operators were involved in the study. The actual status of the pulp was evaluated after the initiation of endodontic treatment, by direct visual examination of the accessed cavity. The data was statistically analysed using (ANOVA) Analysis of Variance and Post-hoc Tukey test. Results: sensitivity of pulse oximeter, heat test, cold and electric pulp test, was 100, 25, 50, and 12, respectively. The specificity of these tests was 100, 72 81, and 77, respectively. The ANOVA showed that there was statistical difference between all the groups (p=0.0005). Post-Hoc Tukey revealed that there was statistical difference among all the groups, nonvital group (p=0.0005), control group (p=0.01) and for irreversible pulpitis (p=0.01). The overall diagnostic accuracy of pulse oximeter was 100% followed by cold test 66%, heat test to be 49% and electric pulp test to be 45%. Conclusion: the custom-made holder used in the present study aided in providing accurate response for pulp vitality testing. In this study the diagnostic accuracy was high with dental pulse oximeter followed by cold, heat and the least was electric pulp tester in different pulpal conditions. (AU)

Fundamentação: a eficiência dos meios de diagnóstico desempenha um papel importante no plano de tratamento. Este estudo tem como objetivo avaliar a precisão diagnóstica do oxímetro de pulso odontológico com um suporte de sensor personalizado, teste térmico e testador de polpa elétrico na avaliação da condição pulpar e na avaliação do nível de saturação de oxigênio em dentes controle saudáveis, não vitais e dentes com pulpite irreversível. Material e métodos: trinta e sete dentes de canal único que necessitavam de terapia endodôntica foram incluídos no estudo. Os dentes selecionados foram testados com oxímetro de pulso, teste pulpar elétrico, spray frio e bastão de guta-percha aquecido. Entre cada teste, foi permitido um intervalo de tempo de 2 minutos para a sensibilização central ocorrer. Três operadores cegos foram envolvidos no estudo. A condição real da polpa foi avaliada após o início do tratamento endodôntico, por meio de exame visual direto da cavidade de acesso. Os dados foram analisados estatisticamente pelo teste de Análise de Variância (ANOVA) e pelo teste Post-hoc de Tukey. Resultados: a sensibilidade do oxímetro de pulso, teste de calor, de frio e teste pulpar elétrico foi de 100, 25, 50 e 12, respectivamente. A especificidade desses testes foi de 100, 72 81 e 77, respectivamente. O teste de ANOVA mostrou que houve diferença estatística entre todos os grupos (p = 0,0005). O teste Post-Hoc de Tukey revelou que houve diferença estatística entre todos os grupos, grupo não-vital (p = 0,0005), grupo controle (p = 0,01) e pulpite irreversível (p = 0,01). A precisão diagnóstica geral do oxímetro de pulso foi de 100%, seguida pelo teste a frio de 66%, o teste de calor a 49% e o teste pulpar elétrico a 45%. Conclusão: o suporte personalizado utilizado no presente estudo ajudou a fornecer uma resposta precisa para o teste de vitalidade pulpar. Neste estudo, a precisão diagnóstica foi alta com o oxímetro de pulso dental, seguido do teste com frio e calor, sendo o teste elétrico o menos eficaz nas diferentes condições pulpares testadas.(AU)

Effect of simulated microgravity on peripheral oxygen saturation in rats / 生物医学工程学杂志

To study the effect of microgravity on peripheral oxygen saturation (SpO ) in rats, tail-suspended rats were applied to simulate microgravity environment. SpO and arterial oxygen saturation (SaO ) were measured by pulse oximeter and arterial blood gas analyzer (ABGA) respectively on the 14th day, 21st day and 28th day in tail-suspended group and control group. Paired -test shows that SpO was significantly lower than SaO in tail-suspended group on the 14th day ( < 0.05), the 21st day ( < 0.05) and the 28th day ( < 0.01). The ANOVA results shows that modeling time had significant effect on SpO value but no effect on SaO value in tail-suspended group. These results indicate that pulse oximeter may be not suitable for oxygen saturation test in microgravity environment.

Comparison of the anesthetic effects of 2,2,2-tribromoethanol on ICR mice derived from three different sources / 한국실험동물학회지

This study was conducted to compare the anesthetic effects of 2,2,2-tribromoethanol (TBE, Avertin®) in ICR mice obtained from three different sources. TBE (2.5%) was intraperitoneally injected at three doses: high-dose group (500 mg/kg), intermediate-dose group (250 mg/kg), and low-dose group (125 mg/kg). Anesthesia time, recovery time, end-tidal peak CO2 (ETCO₂), mean arterial blood pressure, heart rate, oxygen saturation (SpO₂), body temperature, pH, PCO₂, and PO₂ of the arterial blood were measured. Stable anesthesia was induced by all doses of TBE and the anesthesia time was maintained exhibited dose dependency. No significant differences in anesthetic duration were found among the three different strains. However, the anesthesia time was longer in female than in male mice, and the duration of anesthesia was significantly longer in female than in male mice in the high-dose group. The recovery time was significantly longer for female than male mice in the intermediate- and high-dose groups. In the ICR strains tested, there were no significant differences in the mean arterial blood pressure, SPO₂, arterial blood PCO₂, and PO₂, which decreased after TBE anesthesia, or in heart rate and ETCO₂, which increased after TBE anesthesia. In addition, body temperature, blood biochemical markers, and histopathological changes of the liver, kidney, and lung were not significantly changed by TBE anesthesia. These results suggested that ICR mice from different sources exhibited similar overall responses to a single exposure to TBE anesthesia. In conclusion, TBE is a useful drug that can induce similar anesthetic effects in three different strains of ICR mice.

Validación de cinco pulsioxímetros / Validation of five pulse oximeters

Resumen: ANTECEDENTES: la pulsioxímetria estima la saturación arterial de oxígeno mediante la absorción de un haz de luz infrarroja por la oxihemoglobina. OBJETIVO: determinar la validez y la confiabilidad interinstrumento de cinco pulsioxímetros comúnmente usados en la práctica clínica. MATERIAL Y MÉTODO: estudio transversal, analítico, realizado del 1 de enero de 2015 al 30 de octubre de 2016, en el que se incluyeron pacientes mayores de 18 años de edad, con línea arterial para toma de gasometría y se midió simultáneamente la saturación de oxígeno con cinco pulsioxímetros de uso habitual. Se determinaron medianas y porcentajes de los cinco pulsioxímetros entre sí mediante prueba de Friedman. RESULTADOS: se incluyeron 101 pacientes, 63 hombres y 38 mujeres. Se encontró similitud en las mediciones realizadas por cada pulsioxímetro con p = 0.08; todos los oxímetros se correlacionaron de manera positiva contra la prueba patrón de referencia (correlación de Pearson). Oxímetro 1: r = 0.90; oxímetro 2: r = 0.64; oxímetro 3: r = 0.57; oxímetro 4: r = 0.84 y oxímetro 5: r = 0.89; el área bajo la curva mostró oxímetro 1 (0.89), oxímetro 2 (0.88), oxímetro 3 (0.87), oxímetro 4 (0.83), oxímetro 5 (0.85) con p < 0.05. CONCLUSIONES: el pulsioxímetro número 1 muestra el mejor rendimiento comparado con la gasometría. Al comparar los oxímetros entre sí el rendimiento es igual.

Abstract: BACKGROUND: Pulse oximetry estimates the arterial oxygen saturation by absorption of an infrared light beam by oxyhemoglobin. OBJECTIVE: To determine the intraclass validity and reliability of five pulse oximeters commonly used in clinical practice. MATERIAL AND METHOD: A cross-sectional analytical study was done from January 1st 2015 to October 30 2016, including patients over 18 years old, with arterial line for blood gas sample and simultaneously oxygen saturation was measured with 5 pulse oximeters commonly used. Medians and percentages of the 5 pulse oximeters were determined by Friedman's test RESULTS: There were included 101 patients, 63 men and 38 women, with similarity in the measurements performed by each pulse oximeter with p = 0.08; all oximeters were positively correlated against the standard gold test (Pearson's correlation). Oximeter 1: r = 0.90; oximeter 2: r = 0.64; oximeter 3: r = 0.57; oximeter 4: r = 0.84 and oximeter 5: r = 0.89. The area under the curve showed oximeter 1 (0.89), oximeter 2 (0.88), oximeter 3 (0.87), oximeter 4 (0.83), oximeter 5 (0.85) with p < 0.05. CONCLUSIONS: The pulse oximeter number 1 shows a better performance when compared to the gasometry. When the oximeters are compared to each other the performance is the same.

The comparison and selection for saturated pulse oximetry sensor / 中国医学装备

Objective:To expound the importance of blood oxygen saturation index, and to analyze the detection method of oxygen saturation index. Besides, to provide scientific and reasonable basis for use and selection of clinical saturated pulse oximetry(SpO2) sensor. Methods: To adopt pertinence detection method to test six kinds of SpO2 sensors (included the original import, original domestic, import commission processing, domestic commission processing, integrated mode sensor and one-time sensor), and to detect and analyze their specifications.Results: The experiment results of six kinds of SpO2 sensor were analyzed, and their main characteristics were obtained. And then, different sensor was recommended to different department or situation according to the actual situation of different hospital.Conclusion: Various clinical department and requirement can give full play to the advantages of various types of sensor, fast detect blood oxygen index for patients, reasonably allocate SpO2 sensor, reduce using cost and improve diagnosis level, at the same time, effectively carry through adjuvant therapy after they select the most suitable SpO2 sensor.

Effect of creatine phosphate disodium on postoperative cognitive function under combined intravenous and volatile anesthesia in geriatric patients / 解放军医学杂志

Objective To explore the relationship of perioperative INVOS cerebral oxygen saturation (rSO2) and postoperative cognition function alteration of geriatric patients under combined intravenous and volatile anesthesia with creatine phosphate disodium to provide guidance for clinical anesthesia. Methods Sixty ASA I-II patients aged >60 years scheduled for selective abdominal surgeries or surgeries on lower limb were enrolled in the study. The patients were randomly divided into 3 groups of 20 patients: creatine phosphate disodium group 1 (CPD1), creatine phosphate disodium group 2 (CPD2), control group (C). All the patients were not premedicated with atropine 0.5mg until entering the operation room. Anesthesia was induced with intravenous infusion of propofol, fentanyl and cisatracurium slowly, and maintained by inhalational anesthetics sevoflurane 1 MAC plus intravenous infusion of propofol (6-8mg·kg-1·min-1) and remifentanyl (0.2-0.4μg·kg-1·min-1), and intravenous bolus cisatracurium (0.07-0.10mg·kg-1). After tracheal intubation, all the patients were mechanically ventilated with PETCO2 in the normal range. rSO2 was continuously monitored and recorded during the operation. The Mini-Mental State Examination (MMSE), Trailmaking Test and Grooved Pegboard Test were used to access cognitive function 24h before surgery and 4, 8, 12, 24h after surgery. Results (1) There were no significant differences in general status between the three groups (P>0.05). (2) The scores of MMSE, Trail-making Test and Grooved Pegboard Test were not different 24h before the operation between the three groups (P>0.05). (3) The scores of cognitive tests were higher in group CPD2 and group CPD1 than in group C (P0.05). Conclusion CPD can reduce the occurrence of postoperative cognitive dysfunction in geriatric patients under combined intravenous and inhalational anesthesia.

MÉTODO ALTERNATIVO DE CONTROL DE INTENSIDAD LUMÍNICA PARA PULSIOXIMETRÍA EN TIEMPO REAL / AN ALTERNATIVE METHOD FOR POWER CONTROL OF LUMINICINTENSITY IN PULSEOXIMETRY ON REAL TIME / MÉTODO ALTERNATIVO DE CONTROLE DE INTENSIDADE DALUZ PARÁGRAFO OXIMETRIATEMPO REAL

El pulsioxímetro es una herramienta no invasiva esencial para el monitoreo de la saturación arterial de oxígeno. Utiliza la espectrofotometría para detectar sobre la piel dos intensidades de luz (600 y 900 nm) que proporcionan información de la perfusión tisular y cantidad de oxígeno transportada. Depende de un circuito de manipulación de corriente, dos diferentes fuentes emisoras de luz, un foto-detector y una unidad de procesamiento que permiten ajustar las intensidades de luz ante tejidos de diferentes características. En el presente trabajo, se propone un método de modulación por ancho de pulso alternativo para el control de la intensidad lumínica media, cuyo principio es la conmutación on/off de la corriente aplicada a los LEDs en la etapa de emisión. Este sistema permite modificar tanto el nivel de CD como la amplitud de la señal de CA de la onda fotopletismográfica e implica la reducción del número de componentes analógicos y consumo de energía. La metodología presentada permite regular la resolución de la señal muestreada y ofrece disminuciones del 21 % y 40 % en potencia comparado con los esquemáticos propuestos por Freescale Semiconductor, Inc. y Texas Instruments Incorporated respectivamente. El uso de señales sincronizadas moduladas en ancho de pulso con frecuencias por encima de 333 kHz y pasos de 50 ns para emitir luz, permitió una reducción 41% de potencia, respecto al sistema con modulación analógica del módulo MDK pulse oximeter.

Pulse oximetry is an essential optical based non-invasive tool for monitoring blood oxygen saturation. It uses spectrophotometry to detect two light intensities (600 and 900 nm) through the skin; it provides information on tissue perfusion and quantity of transported oxygen. The process relies on a current control circuit, two light emitting sources, a photodetector, and a digital signal processor that adjusts the light intensities for different tissue characteristics. This paper proposes an alternative method of pulse width modulation for controlling the mean light intensity level, whose principle is a pulse width nodulation of the current applied to the LEDs in the emitting stage. This system allows modifying the DC level and the amplitude of the AC signal of the photopletismographic wave. The results is the reduction of the number of analog components and power consumption. The methodology presented, it allows adjusting the definition of the sample signal and offers power reductions of 21% and 40% compared to schematics given by Freescale Semiconductor, Inc. and Texas Instruments Incorporated, respectively. Thus, by using synchronized signal pulse width modulation to emit light, with frequencies above 333 kHz and steps of 50 ns, it will allow power reductions of 41%, compared to the conventional analog modulation module MDK pulse oximeter.

O oxímetro de pulso é uma ferramenta não invasiva essencial para o monitoramento da saturação de oxigênio no sangue. Usa espectrofotometria para detectar a pele duas intensidades de luz (600 nm e 900) para fornecer informações de perfusão tecidual ea quantidade de oxigênio transportado. Depende de manuseamento corrente do circuito, duas fontes diferentes emissores de luz, um fotodetector e uma unidade de processamento para ajustar a intensidade da luz nos tecidos com características diferentes. Neste trabalho, um método de modulação de largura de pulso alternativa para controlar a intensidade de luz média, o princípio é o de ligar/desligar da corrente aplicada aos LEDs no palco questão é proposto. Este sistema permite modificar tanto o nível DC e a amplitude do sinal AC da forma de onda fotoplestimográfico e envolve a redução do número de componentes analógicos e consumo de energia. A metodologia apresentada permite ajustar a resolução do sinal de amostragem e oferece reduções de 21% e 40% da potência em comparação com o esquema proposto pela Freescale Semicondutor, Inc. e Texas Instruments Incorporated, respectivamente. Sinais sincronizados usando freqüências moduladas por largura de pulso acima de 333 kHz e 50 ns passos para emitir luz, permitiu uma redução de 41% de energia em comparação com módulo de oxímetro de pulso MDK sistema de modulação analógica.

Recent advance in patient monitoring / 대한마취과학회지

Recent advance in technology has developed a lot of new aspects of clinical monitoring. We can monitor sedation levels during anesthesia using various electroencephalographic (EEG) indices, while it is still not useful for anesthesia depth monitoring. Some attempts are made to monitor the changes in sympathetic nerve activity as one of the indicators of stress, pain/analgesia, or anesthesia. To know the balance of sympathetic and parasympathetic activity, heart rate or blood pressure variability is investigated. For trend of cardiac output, low invasive monitors have been investigated. Improvement of ultrasound enables us to see cardiac structure and function continuously and clearer, increases success rate and decreases complication of central venous puncture and various kinds of nerve blocks. Without inserting an arterial catheter, trends of arterial oxygen tension or carbon dioxide tension can be monitored. Indirect visualization of the airway decreases difficult intubation and makes it easier to teach tracheal intubation. The changes in blood volume can be speculated non-invasively. Cerebral perfusion and metabolism are not ordinary monitored yet, but some studies show their usefulness in management of critically ill. This review introduces recent advances in various monitors used in anesthesia and critical care including some studies of the author, especially focused on EEG and cardiac output. However, the most important is that these new monitors are not almighty but should be used adequately in a limited situation where their meaning is confirmed.

Skin Burn Associated with Pulse Oximeter : A case report / 대한마취과학회지

A pulse oximeter is used widely on account of its convenience and very few complications. We experienced a case of accidental burning by a pulse oximeter sensor. An 83-year-old woman underwent total hip replacement surgery. A pulse oximeter (Oxisensor II N-25, Nellcor Puritan Bennett Inc., USA) was placed on the left index finger. The patient complained of pain on her index finger 5 minutes after the operation began. A localized skin burn was found underneath the sensor of the pulse oximeter. The skin burn healed without any sequelae.

Precisión y exactitud de un oxímetro de pulso "de bolsillo" en la ciudad de México / Precision and accuracy of "a pocket"pulse oximeter in Mexico City

Background. Pulse oximeters are frequently used in the clinical practice and we must known their precision and accuracy. The objective was to evaluate the precision and accuracy of a "pocket" pulse oximeter at an altitude of 2,240 m above sea level. Methods. We tested miniature pulse oximeters (Onyx 9,500, Nonin Finger Pulse Oximeter) in 96 patients sent to the pulmonary laboratory for an arterial blood sample. Patients were tested with 5 pulse oximeters placed in each of the fingers of the hand oposite to that used for the arterial puncture. The gold standard was the oxygen saturation of the arterial blood sample. Results. Blood samples had SaO2 of 87.2 ± 11.0 (between 42.2 and 97.9%). Pulse oximeters had a mean error of 0.28 ± 3.1%. SaO2 - (1.204 x SpO2) - 17.45966 (r = 0.92, p < 0.0001). Intraclass correlation coefficient between each of five pulse oximeters against the arterial blood standard ranged between 0.87 and 0.99. HbCO (2.4 ± 0.6) did not affect the accuracy. Conclusions. The miniature oximeter Nonin is precise and accurate at 2,240 m of altitude. The observed levels of HbCO did not affect the performance of the equipment. The oximeter good performance, small size and low cost enhances its clinical usefulness.

Introducción. Los oxímetros de pulso son ampliamente utilizados en la práctica clínica y su precisión y exactitud deben conocerse especialmente en altitudes moderadas como en la ciudad de México. El objetivo principal fue evaluar la precisión y exactitud de un oxímetro de pulso "de bolsillo" (Onyx 9500 de Nonin®) en la ciudad de México. Métodos. Se realizaron mediciones de la saturación de oxígeno estimada por el oxímetro de pulso (SpO2) y se compararon contra la medida espectrofotométricamente en sangre arterial (SaO2) en 96 pacientes que acudieron al laboratorio de fisiología pulmonar del Instituto Nacional de Enfermedades Respiratorias. A cada paciente se le colocaron cinco oxímetros de pulso en los dedos de una mano obteniéndose un promedio de SpO2 para cada uno de los oxímetros y para los cinco oxímetros a la vez, mediciones que se compararon de manera simultánea contra el estándar. Resultados. Las muestras sanguíneas de los 96 pacientes que participaron tuvieron una SaO2 de 87.2 ± 11.0 (entre 42.2-97.9%). Los oxímetros (promedio de los cinco) tuvieron un error de medición promedio de 0.28 ± 3.1%. SaO2 = (1.204 x SpO2) - 17.45966 (r = 0.92, p < 0.0001). Los coeficientes de correlación intraclase que se obtuvieron al comparar los oxímetros entre sí y contra el estándar (SaO2) estuvieron entre 0.87 y 0.99. El nivel de carboxihemoglobina (HbCO) fue de 2.4 ± 0.6% y no afectó significativamente la exactitud del oxímetro. Conclusiones. El oxímetro digital de pulso "de bolsillo" es preciso y exacto en la estimación de la SaO2 a 2,240 metros de altitud. Los niveles observados de HbCO (2.4%) no afectaron su exactitud. Se observó un adecuado desempeño del oxímetro digital de pulso en la ciudad de México.

Influence of Repeated Exposures to Hypobaric Chamber on Acute Hypoxia Tolerance / 항공우주의학회지

BACKGROUND: Acute hypoxia tolerance has been evaluated by the time of useful consciousness, subjective symptoms, cardiovascular changes, visual deterioration, psychological performance, and so forth. But these methods are either subjective, lacking strict objectivity, or too demanding to collect sufficient data. Pulse oximeter monitoring has come to be used not only in hospitals but in the aviation environment. This noninvasive oxygen monitoring apparatus warrants a highly objective analysis to investigate acute hypoxia tolerance. METHODS: Eight healthy male volunteers (20-25 years old) were exposed three times to a simulated altitude of 25,000 ft (7,620 m) at intervals of 7 days. We monitored arterial oxygen saturation (SaO2) and pulse rate by a pulse oximeter. The duration from taking the mask off to the time of 60% SaO2 was regarded as acute hypoxia tolerance. The venous hemoglobin concentration was measured a day before exposure to hypoxia. A questionnaire on the 14 subjective hypoxic symptoms was obtained after hypobaric chamber training. RESULTS: There were neither differences of acute hypoxia tolerance, hemoglobin concentration, nor pulse rate according to the repeated exposure of hypoxia. Four symptoms of sleepiness, fatigue, flushing and thinking impairment were sustained regardless of repeated exposures to hypoxia. But the incidence of symptoms of ear pain, anxiety, abdominal pain were reduced according to the repeated hypoxia. CONCLUSION: With pulse oximeter monitoring there was no difference between the values of time of 60% SaO2 in repeated exposures to hypoxia. The incidence of some subjective symptoms was reduced according to the repeated exposures to hypoxia.

Decrease in Pulse Oximeter Readings Following Injection of Isosulfan Blue Dye / 한국유방암학회지

PURPOSE: A sentinel lymph node mapping with blue dye has been well accepted as a common procedure in breast cancer surgery. However, it is well known that blue dye absorbed into the circulation may interfere pulse oximetery reading. The aim of this study was to evaluate the change of pulse oximetery reading by isosulfan blue dye injection during sentinel lymph node mapping. METHODS: Thirteen breast cancer patients with normal preoperative cardiopulmonary functions were studied. Four ml of isosulfan blue dye was injected subdermally when the patient became stable after induction of general anesthesia. The pulse oximetery was monitored continuously. Multiple arterial blood gas analyses (ABGA) were performed before dye injection and 10, 30, 40 minutes after dye injection. The results of oxygen saturturation by oximetery (SpO2) and the results of arterial oxygen tension (SaO2) and arterial oxygen saturation (SaO2) by ABGA were compared. RESULTS: The value of both SaO2 and PaO2 measured by ABGA has not been altered by isosulfan dye injection. However SpO2 decreased by isosulfan dye injection. SpO2 decrease started 8.2+/-1.5 (2~0) minutes after dye injection and returned to preinjection level by 85.7+/-5.6 (60~126) minutes after injection. The lowest vaule of SpO2 was 95.6+/-1.2% (93~97). Mean duration of SpO2 decrease was 77.5+/-6.2 (40~117) minutes. The duration of SpO2 decrease was longer in the aged patients, but it was not statistically significant (p=0.3). There was no siginificant difference in duration of SpO2 decrease according to injection site, operation method, and body mass index (BMI). CONCLUSION: .Isosulfan dye injection using for sentinel lymph node mapping causes no change in true ABGA results but causes a mild reversible decrease in SpO2, It is important to look for other causes when SpO2 decrease is significant and persistent.

Anesthetic Management during Aortic Arch Surgery Using Anterograde Selective Cerebral Perfusion / 대한마취과학회지

Cerebral protection during aortic arch surgery is an anesthetic challenge, since the surgical procedures for aortic arch aneurysm involve an interruption of cerebral blood flow. We report a successfully managed case of aortic arch aneurysm repair with antegrade selective cerebral perfusion (SCP) during TCA (total circulatory arrest) using a transcranial oximeter, cerebral oxygenation was monitored during surgery. Although at the beginning of TCA a decrease in the regional cerebral oxygen saturation was observed, this was soon recovered by SCP. Except for the short period of TCA without SCP, regional cerebral oxygen saturation (rSO2) value were well maintained during surgery.

Reliability of rSO2 to Measure CO2 Reactivity of Cerebral Vasculatures during Desflurane-N2O Anesthesia / 대한마취과학회지

BACKGROUND: Near infrared spectroscopy (NIRS) to monitor regional cerebral oxygen saturation (rSO2) is a noninvasive and simple modal ity in clinical use. The ability of rSO2 as an index of cerebral oxygenation has been well demonstrated. However, the reliability of rSO2 to reflect the changes of cerebral vascular reactivity in the changes of arterial partial pressure of CO2 (PaCO2) has not been established. The aim of this study was to verify the reliability of rSO2 to measure the CO2 reactivity of cerebral vasculatures. METHODS: Twenty healthy adult patients undergoing general anesthesia were enrolled in this study. Anesthesia was induced with propofol and maintained with desflurane/N2O. Respiration was mechanically controlled. The radial artery and jugular bulb were cannulated. The sensor of the NIRS was attached to the ipsilateral forehead. During normocapnia (PaCO2 40 +/- 1.3 mmHg) and hypocapnia (PaCO2 30 +/- 2.4 mmHg), blood was obtained from the radial artery and jugular bulb and analyzed. rSO2 was compared with fSO2 (estimated field oxygen satuation), and the gold standard of tissue oxygen saturation. fSO2 was calculated from the following equation: fSO2 = 0.75 SjO2 + 0.25 SaO2. RESULTS: rSO2 significantly correlated with fSO2 (P = 0.000, r2 = 0.56). A bias of - 5.8% with a precision 12.94% was found. CONCLUSIONS: We concluded that rSO2 can be a reliable predictor to measure CO2 reactivity of cerebral vasculatures during normocapnia and hypocapnia.