The results of in vivo investigation of combined optical and ultrasound methods of tissue oxygenation and their application in medicine are presented. The optical method is based on the phenomenon of laser-induced photodissociation of blood oxyhemoglobin in cutaneous blood vessels. It is shown that this method provides an extraction of additional oxygen directly in the irradiation zone. The acoustic method enhances the efficiency of optically induced tissue oxygenation by improvement in the blood microcirculation. Some biomedical applications of the developed combined opto-ultrasound method of tissue oxygenation are discussed.
The paper presents our results on the study of the efficiency of inter-fractional changes in hemoglobin molecules depending on the laser radiation parameters. The evaluation of the quantum efficiency of light interaction in vivo with oxyhemoglobin (HbO2) and carboxyhemoglobin (HbCO) in the blood at wavelengths for 525 and 605 nm is presented. The photodissociation yield of 11% for HbO2 and 79% for HbCO are measured at the wavelength of 525 nm and 10 % for HbO2 and 76 % for HbCO at a wavelength of 605 nm. Thus, the quantum yield of photodissociation of the HbCO is considerably higher, which ensures high efficiency of photodecomposition of the HbCO in the blood. The obtained results can be used in the clinical phototherapy practice for effective treatment of CO poisoning.
The efficiency of the laser radiation effect on the oxyhemoglobin in blood vessels and its dependence on the wavelength of the irradiation are investigated. In vivo experimental measurements of the quantum yield of the laser-induced photodissociation of oxyhemoglobin in cutaneous blood vessels in the visible spectral range are presented. The spectral effectiveness of the photodissociation approximately correlates with their absorption spectrum and the transmission spectrum of skin tissue. Different aspects of biomedical application of this phenomenon are discussed. Non-invasive three-wavelength technique for determination of oxyhemoglobin concentrations in blood is also developed.
This paper presents an experimental study in vivo of the rate of the carboxyhemoglobin (HbCO) photodissociation in blood under the influence of the transcutaneous laser irradiation in visible spectral range from 405 to 700 nm. Despite the similarity of the HbCO and HbO2 action spectra, the designed 3-wavelengths measurement system makes it possible to obtain reliable measuring of the HbCO decrease level. The results show that there is a relatively narrow spectral range in the visible region where one could effectively (up to 50%) dissociate carboxyhemoglobin in blood through the tissue. The obtained results can be used in clinical practice on phototherapy and for effective treatment of CO poisoning.
The value of relative oxyhemoglobin concentration (saturation) in arterial (SаO2) and venous blood (SvO2) plays a significant role in the oxygen exchange in tissue and is used as criterion of delivery of oxygen adequate to the needs of tissue cells. Reduction of the volume of blood flows as well as reduction of oxygen concentration in arterial blood causes hypoxia - deficit of oxygen in tissue. One of the main mechanisms of elimination of hypoxia is based on compensation of the oxygen deficit by increasing the oxygen extraction from arterial blood, which leads to reduction of oxygen in the venous blood 1. In this report two optical techniques for measurement of venous blood saturation are presented. The first one is based on the pulseoximetry with artificial mechanical modulation of the tissue volume and the second one on the spectrophotometry of human respiratory rhythm. Good correlation between the results obtained with both techniques is observed.
We present the results from numerical simulation of the interaction of laser optical radiation with myoglobin (Mb) and
oxymyoglobin (MbO2) in muscle tissue. It is shown that the photodissociation of MbO2 can modify the concentration of
oxygen (O2) in the muscle tissue directly at the irradiation zone. The criteria of the effectiveness of the combined effect
of biological tissue oxygenation by two-wavelength laser radiation are considered.
A novel method of direct control of local tissue oxygenation based on laser-induced photodissociation of oxyhemoglobin
in cutaneous blood vessels is discussed. New technology in selective and local increase of the concentration of free
molecular oxygen in tissue that enhances metabolism of cells is demonstrated. Direct in vivo measurements of the tissue
oxygen tension are carried out on human skin. Kinetics of oxygen tension in tissue is investigated under the effect of He-Ne laser radiation at the power of 1mW relatively to initial value of tissue oxygen tension. The results of experimental
study the kinetics of oxygen distribution into tissue from arterial blood is presented. Biomedical applications of proposed
new technology in laser therapy of pathologies where elimination of local tissue hypoxia is critical are discussed.
New approach in laser-optical diagnostic methods of cell metabolism based on visualization the local net of tissue blood
vessels is proposed. Optical model of laser - tissue interaction and algorithm of mathematical calculation of optical
signals is developed. Novel technology of local tissue hypoxia elimination based on laser-induced photodissosiation of
oxyhemoglobin in cutaneous blood vessels is developed. Method of determination of oxygen diffusion coefficient into
tissue on the base of kinetics of tissue oxygenation TcPO2 under the laser irradiation is proposed. The results of
mathematical modeling the kinetic of oxygen distribution into tissue from arterial blood are presented. The possibility of
calculation and determination of the level of TcPO2 in zones with the disturbed blood microcirculation is demonstrated.
The increase of the value of oxygen release rate more than for times under the irradiation by laser light is obtained. It is
shown that the efficiency of laser-induced oxygenation by means of increasing oxygen concentration in blood plasma is
comparable with the method of hyperbaric oxygenation (HBO) at the same time gaining advantages in local action.
Different biomedical applications of developing method are discussed.
It is shown that exposure of the human skin by a laser radiation increases the degree of its oxygenation and that an
increase in the skin temperature enhances this effect. The results obtained were coordinated with the data of earlier
theoretical investigations on the mechanism of oxygenation of tissues in the process of laser-induced dissociation of
oxyhemoglobin. The data obtained by independed methods for measuring SaO2 were in good qualitative and
quantitative agreement.
Concentration of oxygen in tissue plays an important role in enhancing in vivo wide variety of biochemical reactions including cell metabolism. Aerobic cell metabolism is primary mechanism in energy production in tissue. Controlling this mechanism gives unique possibility of biological stimulation to reach therapeutic effect. This goal could be reached by laser-induced photodissociation of oxyhemoglobin in cutaneous blood vessels. This phenomenon is considered as a main mechanism of biostimulating and therapeutic effect of low energy laser radiation. Laser-induced photodissociation of oxyhemoglobin in vivo manifests itself through the changes of the value of arterial blood saturation before and during the laser irradiation. High sensitive pulse oxymeter could be used for the measurements of the level of arterial blood saturation. Unique possibility is reached in local increase the concentration of oxygen by additional releasing it into tissue. Laser-induced enrichment of tissue oxygenation stimulates of cell metabolism and allows develop new effective methods for laser therapy as well as phototherapy of pathologies where elimination of local tissue hypoxia is critical.
A new method of laser-induced tissue oxygenation for elimination of tissue hypoxia and increase in the efficiency of the method of Photodynamic Therapy (PDT) is proposed. It is shown that significant increase in the efficiency of PDT due to extra supply of cancer tissue by free oxygen could be reached.
The method of direct control of tissue local oxygen concentration based on in vivo laser-induced photodissosiation of oxyhemoglobin is discussed. This method gives unique possibility in selective and local increase of the concentration of
free molecular oxygen into tissue that enhances metabolism of cells. Novel method of dosimetry based on key biological
parameters connected with aerobic metabolism is discussed. Different biomedical applications of these methods are
proposed.
High sensitive multi channel pulse oxymeter - spectrophotometer for control of the local tissue oxygen saturation is presented. Due to an original method of data storing and processing the accuracy of measurements 3-4 times are increased in compare with similar systems. This system is used for registration of the local changes of arterial blood saturation with oxygen under effect of low intensity laser radiation. It is shown that the photodissociation of oxyhemoglobin in cutaneous blood vessels play a dominant role in the mechanism of biostimulating and therapeutic effect of low intensity laser radiation. The results of experimental investigation in vivo the dependence of arterial oxygen blood saturation on temperature and the wavelength of laser radiation are presented. It is suggested that dosimetry for laser therapy could be base on regulation of local concentration of free oxygen in tissue.
One of the mechanisms of influence of laser radiation on the biological tissue is photodissociation of oxyhemoglobin with releasing of molecular oxygen, thus decreasing the degree of blood oxygen saturation. The experimental study of oxygen saturation of arterial blood under laser action is based on the registration of small variations of the saturation value on the background of the natural saturation oscillations.
While the determination of the value of oxygen saturation allows to observe respiratory processes, the value of venous saturation allows to determine the dynamics and efficiency of the oxygen absorption in tissues, as well as the condition of venous vessels. The tissue and vein oxygen saturation have not been studied sufficiently so far. The simlutaneous control of arterial and tissue saturation values will give opportunity to study the oxygen supply processes.
The aims of this work are experimental study of laser induced photodissociation of oxyhemoglobin and determination of the dependence between the saturation value and the laser parameters. This will allow to develop new methods of control, as well as to realized a feedback during laser therapy.
A new approach to carbon monoxide poisoning treatment based on laser-induced photodissociation of the carboxyhemoglobin is proposed. Using the simple model of laser tissue interaction the action spectra of laser radiation on carboxyhemoglobin of cutaneous blood vessels has been calculated.
The results of the calculatoins indicate that there is a relatively narrow spectral range in the visible region where one could effectively irradiate carboxyhemoglobin through the tissue not in a deep distances. In the case of deeper penetration, the action spectra of laser radiation shifts toward the longer wavelength region.
Despite the similarity of the carboxyhemoglobin and oxyhemoglobin action spectra, the significant difference in quantum yields of photodissociation makes possible to develop an effective method of carbon monoxide poisoning treatment.
In the present report we draw attention to the phenomenon of laser-induced photodissociation of oxyhemoglobin in cutaneous blood vessels as an important factor in biostimulating and therapeutic action of low energy laser radiation. Calculations of absorption efficiency of laser radiation both by oxyhemoglobin and carbon monoxide hemoglobin were carried out by a computer simulation using Kubelka-Munk model of tissue. It has been shown that the absorption of the oxyhemoglobin in the visible region corresponding to the Q-band of absorption spectra possesses a relatively high selectivity. The obtained results are discussed in terms of developing new methods for wound healing, as well as for carbon monoacid poisoning. Some aspects of the laser-induced photodissociation of oxyhemoglobin complexes are discussed in view of its practical use for developing new diagnostic methods. An attractive way to use this phenomenon is monitoring of local concentrations of oxygen by laser light irradiation.
The efficiency of light absorption by oxyhemoglobin and deoxyhemoglobin in cutaneous blood vessels in dependence of the radiation wavelength and optical properties of the tissue is investigated. The main goal is to develop the practical application of long pulse flashlamp-pumped dye lasers in the treatment of different cutaneous lesions, based on the selective photothermolysis. The spectra of laser action both on oxyhemoglobin and deoxyhemoglobin of blood vessels at different depths of the tissue layer were calculated using the Kubelka-Munk optical model of the tissue. The obtained results allow to choose the proper wavelength of laser radiation for the selective and efficient influence on the blood chromophores. It is shown that for blood vessels located in tissue up to the depth of 2500 (mu) the action spectra of laser radiation follow the shape of the Q - absorption bands of oxyhemoglobin and deoxyhemoglobin. At deeper layers the action spectra become very narrow ((delta) (lambda) on the order of magnitude 25 - 30 nm) and shift to the long wavelength with maximum at 585 nm and 570 nm for oxyhemoglobin and deoxyhemoglobin, accordingly. The action spectra in the near infrared region remain very broad and cover the range from 600 nm to 1200 nm. It is shown that these bands play the dominant role in the absorption of laser radiation in deeper layers of tissue.
The action spectra on hemoglobin and oxyhemoglobin of cutaneous blood vessels in dependence of the depth of penetration of laser radiation on tissue is investigated. The obtained results allows to choose the proper wave-length of laser radiation for a selective and efficient action on blood chromophors. There is a narrow action spectrum in a visible spectral range in activation of photochemical processes or biostimulation mechanisms through the impact on the oxyhemoglobin on deep layer of cutaneous blood vessels. The primary mechanism of biostimulation and therapeutic effect of low energy laser radiation based on local increasing of efficiency of oxygen transportation by oxyhemoglobin of cutaneous blood vessels is discussed.
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