Anders Jarlov - Academia.edu (original) (raw)
Papers by Anders Jarlov
International journal of biomedical and clinical engineering, Jul 1, 2019
External defibrillation involves short electric shocks of several thousand volts applied to the c... more External defibrillation involves short electric shocks of several thousand volts applied to the chest of patients suffering from heart stop. The shock coordinates disorganized muscle fibers of the heart which then can resume normal activity. Implanted pacemakers monitor the natural electrical activity of the heart via electrodes mounted permanently on the inside of the heart. If this activity is insufficient, the pacemaker stimulates the heart muscle by applying a short electrical impulse of a few volts. During the period of defibrillation, voltage differences arise simultaneously between various locations of the body preventing recordings of the hearts natural activity. In order to quantify parameters determining voltage and current in a conductive medium or in a myocardium when defibrillator and pacemaker electrodes are present simultaneously, impedances between electrodes positioned on conductive materials were recorded in laboratory set ups, and the methods were tested using a porcine heart in vitro.
International Journal of Biomedical and Clinical Engineering, 2017
The electrical impedance between skin-electrodes placed at the intact skin can be a source of art... more The electrical impedance between skin-electrodes placed at the intact skin can be a source of artefacts when small electrical voltages such as ECG- and EEG-signals are recorded. This is mainly due to random variations of the electrical properties of the electrode-skin interface. To reduce the effect of these shortcomings, the skin is prepared with conductive paste and sometimes stripped to remove the outer corneous layer of the skin at the sites where the electrodes are placed. That reduces the impedance between the electrode and the skin and subdues disturbing electrical signals emanating from external sources. Numerous electrical models have been presented in the literature in order to relate electrical parameters to physiological and anatomical properties of the skin and to counteract the distortion of electrical signals recorded from the skin surface. To meet these requirements flexible electrodes combined with biochemical sensors have been developed which seem to prepare the wa...
International Journal of Biomedical and Clinical Engineering, 2014
The relationship between surface temperature and heat transfer in a section of isotropic material... more The relationship between surface temperature and heat transfer in a section of isotropic material with plane parallel sides, in this context simulating human skin, can be attained by means of analogue models. A model, in the form of electric circuits, enables the analogue functions to be recorded as electrical signals. Analogue heat transfer rates derived by processing voltage data from the models can be used for the determination of analogue measures of blood perfusion of the skin, which is generally stated in terms of ml blood flow per 100 ml tissue per minute. Analogue time scales can be compressed, reducing recording times of analogue functions, and inaccessible sites of actual tissues can be made accessible for observation in a model version. Lengthy calculations and the development of formulas can be substituted with the recording of analogue functions. The ability of a perfusable material to simulate the skin model is estimated by how well the material, when subjected to know...
Med Biol Eng Comput, 1981
A mathematical model describing the dilution of indicator substance into a pulsatile flow through... more A mathematical model describing the dilution of indicator substance into a pulsatile flow through two series-connected mixing compartments was used for the determination of the volumes of the compartments. When the volumes are of the same order of magnitude, minor errors in the experimentally determined parameters of the dilution curve can lead to gross errors in the calculated volume values. A data-retrieval procedure was developed, which to some extent takes into account the effect of experimental inaccuracy.
Medical & Biological Engineering, 1970
Page 1. Med. & bioL Engng. Vol. 8 ,pp. 221-239. Pergamon Press 1970. Printed in G... more Page 1. Med. & bioL Engng. Vol. 8 ,pp. 221-239. Pergamon Press 1970. Printed in Great Britain LEFT VENTRICULAR VOLUME AND CARDIAC OUTPUT OF THE CANINE HEART APPLICATION OF A MATHEMATICAL TWO ...
Medical & Biological Engineering & Computing, 1979
A bolus of indicator substance injected into a ventricle or an atrium will be diluted in a stepwi... more A bolus of indicator substance injected into a ventricle or an atrium will be diluted in a stepwise manner according to the pulsatile nature of bloodflow. Provided the indicator is dispersed immediately and uniformly in the ventricle or atrium the time course of the indicator can be predicted. Dilution curves recorded in three dog experiments demonstrate a stepwise change of the indicator concentration in the ascending aorta following a bolus injection into the left atrium. The information thus retrieved is entered into equations describing the mathematical model in order to calculate the distribution volumes of the indicator in the left atrium and ventricle.
Medical & Biological Engineering & Computing, 1981
A flow simulator designed to produce well defined pulsatile flows of water through two seriesconn... more A flow simulator designed to produce well defined pulsatile flows of water through two seriesconnected compartments is used to simulate either the right or the left side of the heart. The stroke volume and the diastofic volume of one of the compartments can be preset to desired values. In 14 experiments comprising 102 indicator recordings cold 5% dextrose solution and ink were used as indicators being injected as bofi at a defined instant during the pumping cycle by means of a power injector. A data-retrieval procedure based on a mathematical two-compartment model is used to calculate stroke volumes and ventricular volumes using the indicator recordings as input data. The results are compared with the actual volumes and acceptable agreement was obtained in nine experiments.
Investigative Radiology, 1970
Acta Anaesthesiologica Scandinavica, 1962
Acta Anaesthesiologica Scandinavica, 1962
The relationship between surface temperature and heat transfer in a section of isotropic material... more The relationship between surface temperature and heat transfer in a section of isotropic material with plane parallel sides, in this context simulating human skin, can be attained by means of analogue models. A model, in the form of electric circuits, enables the analogue functions to be recorded as electrical signals. Analogue heat transfer rates derived by processing voltage data from the models can be used for the determination of analogue measures of blood perfusion of the skin, which is generally stated in terms of ml blood flow per 100 ml tissue per minute. Analogue time scales can be compressed, reducing recording times of analogue functions, and inaccessible sites of actual tissues can be made accessible for observation in a model version. Lengthy calculations and the development of formulas can be substituted with the recording of analogue functions. The ability of a perfusable material to simulate the skin model is estimated by how well the material, when subjected to known perfusions with water, exhibit surface temperatures that agree with the corresponding analogue properties of the electrical model. The materials and methods are tentatively applied to recordings of perfusion of human skin.
International journal of biomedical and clinical engineering, Jul 1, 2019
External defibrillation involves short electric shocks of several thousand volts applied to the c... more External defibrillation involves short electric shocks of several thousand volts applied to the chest of patients suffering from heart stop. The shock coordinates disorganized muscle fibers of the heart which then can resume normal activity. Implanted pacemakers monitor the natural electrical activity of the heart via electrodes mounted permanently on the inside of the heart. If this activity is insufficient, the pacemaker stimulates the heart muscle by applying a short electrical impulse of a few volts. During the period of defibrillation, voltage differences arise simultaneously between various locations of the body preventing recordings of the hearts natural activity. In order to quantify parameters determining voltage and current in a conductive medium or in a myocardium when defibrillator and pacemaker electrodes are present simultaneously, impedances between electrodes positioned on conductive materials were recorded in laboratory set ups, and the methods were tested using a porcine heart in vitro.
International Journal of Biomedical and Clinical Engineering, 2017
The electrical impedance between skin-electrodes placed at the intact skin can be a source of art... more The electrical impedance between skin-electrodes placed at the intact skin can be a source of artefacts when small electrical voltages such as ECG- and EEG-signals are recorded. This is mainly due to random variations of the electrical properties of the electrode-skin interface. To reduce the effect of these shortcomings, the skin is prepared with conductive paste and sometimes stripped to remove the outer corneous layer of the skin at the sites where the electrodes are placed. That reduces the impedance between the electrode and the skin and subdues disturbing electrical signals emanating from external sources. Numerous electrical models have been presented in the literature in order to relate electrical parameters to physiological and anatomical properties of the skin and to counteract the distortion of electrical signals recorded from the skin surface. To meet these requirements flexible electrodes combined with biochemical sensors have been developed which seem to prepare the wa...
International Journal of Biomedical and Clinical Engineering, 2014
The relationship between surface temperature and heat transfer in a section of isotropic material... more The relationship between surface temperature and heat transfer in a section of isotropic material with plane parallel sides, in this context simulating human skin, can be attained by means of analogue models. A model, in the form of electric circuits, enables the analogue functions to be recorded as electrical signals. Analogue heat transfer rates derived by processing voltage data from the models can be used for the determination of analogue measures of blood perfusion of the skin, which is generally stated in terms of ml blood flow per 100 ml tissue per minute. Analogue time scales can be compressed, reducing recording times of analogue functions, and inaccessible sites of actual tissues can be made accessible for observation in a model version. Lengthy calculations and the development of formulas can be substituted with the recording of analogue functions. The ability of a perfusable material to simulate the skin model is estimated by how well the material, when subjected to know...
Med Biol Eng Comput, 1981
A mathematical model describing the dilution of indicator substance into a pulsatile flow through... more A mathematical model describing the dilution of indicator substance into a pulsatile flow through two series-connected mixing compartments was used for the determination of the volumes of the compartments. When the volumes are of the same order of magnitude, minor errors in the experimentally determined parameters of the dilution curve can lead to gross errors in the calculated volume values. A data-retrieval procedure was developed, which to some extent takes into account the effect of experimental inaccuracy.
Medical & Biological Engineering, 1970
Page 1. Med. & bioL Engng. Vol. 8 ,pp. 221-239. Pergamon Press 1970. Printed in G... more Page 1. Med. & bioL Engng. Vol. 8 ,pp. 221-239. Pergamon Press 1970. Printed in Great Britain LEFT VENTRICULAR VOLUME AND CARDIAC OUTPUT OF THE CANINE HEART APPLICATION OF A MATHEMATICAL TWO ...
Medical & Biological Engineering & Computing, 1979
A bolus of indicator substance injected into a ventricle or an atrium will be diluted in a stepwi... more A bolus of indicator substance injected into a ventricle or an atrium will be diluted in a stepwise manner according to the pulsatile nature of bloodflow. Provided the indicator is dispersed immediately and uniformly in the ventricle or atrium the time course of the indicator can be predicted. Dilution curves recorded in three dog experiments demonstrate a stepwise change of the indicator concentration in the ascending aorta following a bolus injection into the left atrium. The information thus retrieved is entered into equations describing the mathematical model in order to calculate the distribution volumes of the indicator in the left atrium and ventricle.
Medical & Biological Engineering & Computing, 1981
A flow simulator designed to produce well defined pulsatile flows of water through two seriesconn... more A flow simulator designed to produce well defined pulsatile flows of water through two seriesconnected compartments is used to simulate either the right or the left side of the heart. The stroke volume and the diastofic volume of one of the compartments can be preset to desired values. In 14 experiments comprising 102 indicator recordings cold 5% dextrose solution and ink were used as indicators being injected as bofi at a defined instant during the pumping cycle by means of a power injector. A data-retrieval procedure based on a mathematical two-compartment model is used to calculate stroke volumes and ventricular volumes using the indicator recordings as input data. The results are compared with the actual volumes and acceptable agreement was obtained in nine experiments.
Investigative Radiology, 1970
Acta Anaesthesiologica Scandinavica, 1962
Acta Anaesthesiologica Scandinavica, 1962
The relationship between surface temperature and heat transfer in a section of isotropic material... more The relationship between surface temperature and heat transfer in a section of isotropic material with plane parallel sides, in this context simulating human skin, can be attained by means of analogue models. A model, in the form of electric circuits, enables the analogue functions to be recorded as electrical signals. Analogue heat transfer rates derived by processing voltage data from the models can be used for the determination of analogue measures of blood perfusion of the skin, which is generally stated in terms of ml blood flow per 100 ml tissue per minute. Analogue time scales can be compressed, reducing recording times of analogue functions, and inaccessible sites of actual tissues can be made accessible for observation in a model version. Lengthy calculations and the development of formulas can be substituted with the recording of analogue functions. The ability of a perfusable material to simulate the skin model is estimated by how well the material, when subjected to known perfusions with water, exhibit surface temperatures that agree with the corresponding analogue properties of the electrical model. The materials and methods are tentatively applied to recordings of perfusion of human skin.