Thesis (Ph. D.)--University of Wisconsin--Madison, 1982. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis--Wisconsin. / Vita. Includes bibliographical references (leaves 196-203).

Thesis (Ph. D.)--Cornell University. / "From the Psychological laboratory of Cornell university." "Reprinted from the American journal of psychology, October, 1905, vol. XVI, pp. 409-483." Bibliography: p. 73, 75.

Pneumatic tourniquets are in common use in hospitals to stop the flow of blood to a limb or digit and provide a bloodless surgical site. The risk of injury to the tissue beneath the tourniquet cuff from the high pressure in the cuff could be minimized with a tourniquet system capable of maintaining the cuff pressure at the occlusion pressure, which is defined to be the minimum pressure that will stop the flow of blood past the cuff. In the work described in this thesis, a novel impedance-based method was developed to estimate the occlusion pressure while blood flow is arrested by a tourniquet cuff. This should facilitate the development of actual practical tourniquet systems capable of safely and reliably maintaining the tourniquet cuff pressure near the occlusion pressure for the duration of a surgical procedure. The impedance of the tissue beneath the cuff was measured with a specially designed impedance plethysmograph. The electrode configurations used with the plethysmograph were evaluated with a computer model of the limb. A relationship was found between the impedance of the underlying tissue and the cuff pressure relative to the occlusion pressure that could be used to predict the nearness of the onset of blood flow. Eighteen subjects were used in the trials to establish the relationship. The occlusion pressure was typically 150 mmHg and the standard error of estimation was 16 mmHg. To establish the relationship, the tissue pressure profile along the arm beneath the cuff was measured with a special transducer and controlled by varying the pressures in the bladders of a dual-bladder tourniquet cuff used to arrest blood flow. An algorithm based on the relationship was developed to control the bladder pressures according to the impedance of the underlying tissue. The feasibility of a tourniquet system that uses impedance plethysmography to keep the cuff pressure as close as possible to the occlusion pressure while still preventing blood flow was demonstrated with a single subject by controlling the pressures in a dual-bladder tourniquet cuff placed about his arm using the algorithm. Sources of interference and artifact encountered in the study are discussed, and techniques for removing the artifact presented. The major contributions of the research in this thesis were as follows: 1) the development of a computer model for predicting the performance of electrode configurations; 2) the development, design, implementation, and evaluation of a novel impedance plethysmograph; 3) the measurement of the actual tissue pressure profile along the surface of the arm beneath various occlusive cuffs; 4) the discovery of a quantitative relationship between the pressure in a tourniquet cuff and the impedance of the underlying tissue which for the first time enables the prediction of the occlusion pressure while the tourniquet cuff pressure is above the occlusion pressure; 5) the identification and prioritization of the sources of artifact and interference together with the development of approaches for detecting and handling them; and 6) the establishment of the feasibility of controlling the pressure in a tourniquet cuff by incorporating the above into a practical adaptive tourniquet system. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

The purpose of this study was to examine the effects of hydration on %BFADP while using %BFDEXA as the criterion measure. Twenty healthy males and females ages 20-28 participated in the study. The subjects underwent dehydration in the environmental chamber at 32°C and 50% relative humidity until a total of 3% of their body weight had been lost. Subjects were measured with ADP and DEXA at euhydration, 1%, 2%, and 3% dehydration. The results revealed significant differences between %BFADP and %BFDEXA at each level of hydration. %BFDEXA did not change due to dehydration; however, %BFADP decreased as a result of dehydration. Therefore, standardization criteria must be employed in order to assure proper hydration and accurate %BF measurements via ADP. / School of Physical Education

Thesis (Ph. D.)--Northeastern University, 2008. / Title from title page (viewed April 28, 2009) Graduate School of Arts and Sciences, Dept. of Physics. Includes bibliographical references (p. 123-125).

Thesis (M.S.)--Boise State University, 2009. / Includes abstract. Includes bibliographical references (leaves 33-36).

Thesis (M.S.)--Boise State University, 2009. / Title from t.p. of PDF file (viewed May 12, 2010). Includes abstract. Includes bibliographical references (leaves 33-36).

No description available.

We have developed a multiple-wavelength photo-plethysmograph (MWP) to study skin blood flow. Focused incandescent light is reflected from tissue near the surface and through narrow bandwidth optical filters. The intensity of the reflected light is modulated by the pulsing changes in blood volume; the amount of modulation corresponds to the absorption of blood at particular wavelengths. Four narrow bandwidth optical filters were used during the study (560, 580, 810, and 950 nm). Force was applied (in increments), through the instrument, to the skin, in an effort to extinguish the pulsations. A localized hyperemic response was induced by the reduced blood flow to the tissue. Clinical and non-clinical use of the MWP has been demonstrated. In the nonclinical setting we collected waveforms from bony and soft tissues of a normal healthy subject population. The clinical study took place in the Podiatry Clinic at the Veteran's Administration Hospital in Tucson, Az., on an all male, age matched normal, diabetic and vascularly compromised population. Clinical data were collected from the tips of the right and left great toes after systolic pressures were measured with doppler ultrasound. Data consists of maximum amplitudes, maximum rates of change in the systolic rise, systolic slopes, and spectral power in several frequency bands of detected waveforms. Statistical tests for significance were performed on all the data, and included tests between: hyperemic and non-hyperemic data, clinical population groups, left and right great toe data of the clinical populations, and between data derived from different wavelengths of light. Significant differences (t < .05) were most consistently found in light filtered at 580 nm. Significant differences for the non-clinical population existed between hyperemic and non-hyperemic data at soft and bony locations. Significance existed between the clinical groups of general and compromised patients, diabetic and compromised patients, but not between general and diabetic patients. Correlation between measured toe pressures and data of the three clinical groups showed a slight positive bias. No significance was found to exist for the three clinical groups between data derived with light of different wavelengths (580 and 810 nm.).