RESUMEN
Based on the principles of organizational optics, the noninvasive tissue oxygenation saturation monitor was developed. The monitor was used to continuously monitor the changes in regional oxygen index of the thigh vastus lateralis in 101 volunteers, who performed an incremental intensity exercise on bicycle ergometer. Among the volunteers, 42 are athletes, 25 are patients whose spleens are asthenic, and the other 34 are controls. Hemoglobin concentration (CtHb) measured was heavily influenced by the thickness of fattiness; however, regional oxygen saturation (rSO2) was influenced much lightly. In the experiment, following increasing exercise intensity of the volunteers, their CtHb increased, while their rSO2 decreased. When the volunteers stopped the exercise, both of their C1Hb and rSO2 increased quickly. The results showed that the regional saturation of oxygen of muscle was closely correlated with physical performance. The changes of regional saturation of oxygen of muscle can be used to evaluate the balance between supply and consumption of oxygen, and quantitatively assess the capability of oxidative metabolism in muscles.
Asunto(s)
Músculos/fisiología , Oxígeno , Espectroscopía Infrarroja Corta , Fenómenos Biomecánicos , Prueba de Esfuerzo , Humanos , Consumo de OxígenoRESUMEN
Based on the absorption spectra of hemoglobin and myoglobin in the near infrared band, the concentrations of these pigments in the biological tissues can be obtained using near infrared spectroscopy (NIRS) by detecting the intensity attenuation of the emitted light compared with the incident light. Based on the steady-state spatially resolved NIRS, the prototype for detecting the concentrations of tissue hemoglobin and myoglobin was independently developed by our group. The probe consisted of an LED light source which could emit three different wavelengths in the near infrared band, and two detectors which were placed on the same line with and at the distances of 30/40 mm to the LED. The pigment concentrations of two pieces of pork, one from the erector spinae and the other from the rectus femoris, were detected using this prototype. The total concentrations of hemoglobin and myoglobin (c(total)) were (6.42 + 1.51) micromol x L(-1) in the erector spinae, and (15.48 +/- 4.54) micromol x L(-1) in the rectus femoris, respectively. The myoglobin was dominant in both of the results. These were consistent with the recent empirical reports. In summary, the NIRS method and prototype are authentic in detecting the pigment concentrations of pork tissue non-invasively, real-time, directly and conveniently.
Asunto(s)
Hemoglobinas/análisis , Carne/análisis , Músculo Esquelético/química , Mioglobina/análisis , Espectroscopía Infrarroja Corta , Animales , Pigmentos Biológicos/análisis , PorcinosRESUMEN
An infrared thermogram which reflects the human body surface temperature distribution can be obtained through detecting the infrared thermal radiation from each point on the human body surface. When a malignant tumor occurs in a breast, it will cause an increase in the prominent temperature in the breast surface focus region due to the abnormal blood transmission state of local focus tissue. Breast cancer can be detected through the visual analysis of the focus regions by physicians. In order to help physicians better find these focus regions, the present paper improved the traditional pseudo color display method by introducing visual effect factor and made the focus regions have a better display effect. The efficacy of this method was verified in the breast infrared thermograms of 47 breast cancer patients. The result from visual analysis of the focus region in infrared thermogram by this method can also be compared with the tissue blood transmission state from near infrared spectroscopy (NIRS) and other methods. It will be helpful to obtain more accurate diagnostic information.
Asunto(s)
Mama/citología , Gráficos por Computador , Rayos Infrarrojos , Termografía , Anciano , Mama/patología , Neoplasias de la Mama/diagnóstico , Neoplasias de la Mama/patología , Color , Femenino , Humanos , TemperaturaRESUMEN
Human tissue oxygen saturation (rSO2) can be monitored non-invasively and in real time by near infrared spectroscopy (NIRS) based on spatially-resolved spectroscopy. To expand the clinical applications of the NIRS oximeter developed by our group based on the above principle, the accuracy of rSO2 must be ensured and enhanced as far as possible. In the present paper, the influences of the probe configuration, especially the distance between the detectors and the wavelength discreteness of the light source, on the accuracy of rSO2 were discussed. The results indicate that (1) to obtain rSOz accurately, two detectors need to be used, where the distance between them should be in the range of 5-20 mm and they should be both at least 20 mm apart from the light source; (2) there can be significant error in rSO2 (> 10%) induced by the discreteness of the two emission wavelengths especially the shorter one of the light source, so the real emission wavelengths must be accurately measured and the corresponding extinction coefficients of deoxygenated and oxygenated hemoglobin (Hb and HbO2) must be used in order to avoid this error. The above conclusions can be the guidance to optimally design the probe, which has been achieved in our NIRS oximeter.
Asunto(s)
Oximetría/métodos , Oxígeno/análisis , Espectroscopía Infrarroja Corta/métodos , Humanos , Oximetría/instrumentación , Espectroscopía Infrarroja Corta/instrumentaciónRESUMEN
As a non-invasive technique for measuring tissue oxygenation, near-infrared spectroscopy (NIRS) has increasing applications in detecting cerebral hypoxia-ischemia. The authors, introduced the basic principle of the NIRS oximeter developed independently by our group (TSAH-100). The authors achieved the optimal coupling between the probe and the detected cerebral tissue. The present study investigated different regional oxygen saturations of brain (rSO2) measured non-invasively by NIRS, arterial blood oxygen saturation (SaO2) measured invasively by blood gas analysis and physiological parameters in newborn pigs with different hypoxia, in order to prove if the non-invasively cerebral rSO2 can indicate cerebral oxygenation status in clinical practice. Using this oximeter, cerebral rSO2 of 28 newborn piglets under different oxygenation status was detected. After mechanical ventilation and inhalation of 8%-17% oxygen for 30 min in the newborn pigs, the pigs were grouped according to the inhalation of oxygen. With the inhalation of 13%-17% oxygen was mild hypoxia group, with 10%-13% was moderate hypoxia group, and with 8%-10% was severe hypoxia group. There were 4 animals in mild hypoxia group, 8 animals in moderate hypoxia group, 12 animals in severe hypoxia group and 4 animals were in the normal control group. The physiological parameters were monitored during the experiment. The SaO2 were invasively measured by blood gas analysis after the experiment. The results indicate that both rSO2 and SaO2 decreased after different degree of hypoxia and there was a good correlation between cerebral rSO2 non-invasively measured by NIRS and SaO2 invasively measured by blood gas analysis (p<0.001). Cerebral rSO2 was also consistent with the degree of hypoxia and the changes in physiological parameters after hypoxia. The arterial pH and the mean arterial pressure (MAP) in the severe hypoxia group was lower than that in the control group (p<0.05). The blood lactic acid in the severe hypoxia group was higher than that in the control group (p<0.05). Thus, the rSO2 can accurately and directly indicate cerebral oxygenation status and can also replace the SaO2 invasively measured by blood gas analysis. Cerebral hypoxia-ischemia can be non-invasively and conveniently diagnosed using NIRS.
Asunto(s)
Hipoxia-Isquemia Encefálica/diagnóstico , Espectroscopía Infrarroja Corta , Animales , Animales Recién Nacidos , Hipoxia-Isquemia Encefálica/sangre , Oxígeno/sangre , Oxígeno/metabolismo , PorcinosRESUMEN
OBJECTIVE: To study correlation of brain hypoxia of different degrees with brain function and damage. METHODS: The brain regional oxygen saturation (rSO2) was determined by using a non-invasive near infrared spectroscopy (NIRS) technique in 15 piglets; the piglets were subjected to inhale 3% - 11% oxygen-nitrogen mixed gas through mechanical ventilation for 30 min. The piglets were divided into groups according to the level of brain rSO2 (i.e. < 30%, 30% - 35%, 35% - 40%, and 40% - 50%), and the data were compared with those of the control group (rSO2 > 60%). Changes of brain function were detected through amplitude and frequency of EEG waves and signal complexity. The piglets were sacrificed via decapitation 72 h after brain damage, and then histopathological and ultrastructural examinations were performed on cerebral cortex and hippocampal CA1 area. RESULTS: In the group with rSO2 > 40%, the mean arterial pressure (MAP) after hypoxia was (56 +/- 0.00) mm Hg (1 mm Hg = 0.133 kPa), the blood lactic acid (LA) was (2.3 +/- 1.2) mmol/L, the EEG findings were within normal range, and there was no change in brain tissue ultrastructure. In the group with brain rSO2 = 30% approximately 40%, the MAP was (73 +/- 8) mm Hg, the LA was (8.2 +/- 3.9) mmol/L, the EEG waves showed decreased amplitude, frequency and complexity, but restored to some extent after hypoxia. The brain tissue ultrastructure showed damages to the cerebral cortex and neuron mitochondria at hippocampal CA1 area. In the group with brain rSO2 < 30%, the MAP was (35 +/- 0) mm Hg, the LA was (12 +/- 2) mmol/L, the EEG showed decreased amplitude, frequency, and complexity of signals compared with those of the normal control group, and was difficult to restore after hypoxia in some of the piglets; the brain tissue ultrastructure appeared to be similar to the changes seen with high-degree swollen cerebral cortex and neuron mitochondria at hippocampal CA1 area. CONCLUSION: Different degrees of hypoxia had different influence on brain function and brain damage. The lower the brain rSO2, the more severe the damages to the brain and its function. The rSO2 of brain tissues detected with noninvasive NIRS can reflect brain injury and its severity during cerebral anoxia.
Asunto(s)
Lesiones Encefálicas/complicaciones , Hipoxia Encefálica/complicaciones , Consumo de Oxígeno , Oxígeno/metabolismo , Espectroscopía Infrarroja Corta/métodos , Animales , Análisis de los Gases de la Sangre , Corteza Cerebral/fisiopatología , Circulación Cerebrovascular/fisiología , Electroencefalografía , Femenino , Hipoxia/metabolismo , Hipoxia/patología , Hipoxia-Isquemia Encefálica/fisiopatología , Masculino , Neuronas/patología , Oximetría/instrumentación , Estadística como Asunto , PorcinosRESUMEN
To avoid cerebral hypoxia caused by the imbalance between cerebral oxygen supply and consumption, regional cerebral oxygenation of patients need to be monitored at real time during cardiopulmonary bypass (CPB) surgery, and the physiological parameters can be regulated and emergent treatment can be used according to it. Using the near infrared (NIR) instrument developed by our group, cerebral oxygenation of the patients under cardiac surgery was monitored. The instrument consists of a two-wavelength near infrared light source and two near infrared detectors. Hemoglobin concentration changes of regional cerebral tissue were calculated, and by steady-state spatially resolved spectroscopy (SRS) algorithm, regional cerebral oxygen saturation (rSO2) was also calculated. Physiological parameters of patients, such as mixed venous oxygen saturation (SvO2), were measured by another monitor during CPB. Hemoglobin concentration changes were easily disturbed, but the anti-disturbance ability of rSO2 was good. The value of rSO2 could be detected all over the surgeries, but SvO2 could be detected only during CPB. There were positive correlations between rSO2 and SvO2 in most of the patients, but the correlation coefficients were not very high. This was because SvO2 reflects the saturation of the main venous, but rSO2 reflects regional cerebral oxygenation. So the physiological meaning of rSO2 and SvO2 is different. The results indicate that cerebral oxygenation of patients can be reflected by rSO2 during CPB, while only monitoring SvO2 is not enough.