Charles S. Lessard

Use of motor nerve conduction testing and vibration sensitivity testing as screening tools for carpal tunnel syndrome in industry

Increased attention to carpal tunnel syndrome in industry has resulted in the development of several proposed screening tests. This investigation evaluated the use of two portable devices for measuring motor nerve conduction time and tactile sensitivity to 120 Hz vibration in a field setting. Forty-seven control participants, 63 manufacturing plant workers with and without symptoms of carpal tunnel syndrome, and 22 patients with physician-diagnosed carpal tunnel syndrome were tested with the NervePace electroneurometer and the Vibration II vibration threshold measurement device. Nerve conduction time differed significantly between the controls, the asymptomatic workers, and the participants with carpal tunnel syndrome or symptoms of carpal tunnel syndrome. The vibration threshold was higher in the carpal tunnel syndrome group than in the other groups; however, further examination of the data revealed no differences in threshold unless nerve conduction time exceeded the control mean by at least three standard deviations. The false-negative rates associated with the tests limit their usefulness in screening for carpal tunnel syndrome.

A study for the development of a noninvasive continuous blood pressure measuring system by analyzing radial artery pulse from a wrist

The appropriate pressure transducer and the prototype system for noninvasive measurement of blood pressure was developed to detect blood pressure pulse from radial artery on the wrist. Three signals, intra-arterial pressure pulse, radial artery pulse, and FSR output were collected from 5 patients during surgery. The results showed that the phasic configuration of two waveforms, intra-arterial pressure pulse and radial artery pressure pulse, was remarkably similar when the wrist strap was fastened to the point which made the arterial pressure pulse waveform to a maximum peak-to-peak value.

Analysis of nystagmus response to pseudorandom velocity input

This report describes a method to analyse the vestibular system when subjected to a pseudorandom angular velocity input. A sum of sinusoids (pseudorandom) input lends itself to analysis by linear frequency methods. Resultant horizontal ocular movements were digitized, filtered and transformed into the frequency domain. Programs were developed and evaluated to obtain the auto spectra of input stimulus and resultant ocular response, cross spectra, the estimated vestibular-ocular system transfer function gain and phase, and coherence function between stimulus and response functions.

Estimation Of Bac From The Analysis Of Nystagmus

This paper presents a computer-automated process for measuring ocular nystagmus and using these nystagmuscharacterizing parameters to estimate blood alcohol concentration (BAC). Alcohol is administered to reach target BAC of 0.15%. The alcohol dose is divided into four equal parts and administered at 15-minute intervals. BAC is determined through breath analysis and the horizontal component of the electro-oculogram (EOG) to sinusoidal and lateral gaze stimuli is recorded. Various nystagmus parameters indicative of horizontal alcohol gaze nystagmus (HAGN) and horizontal pursuit alcohol nystagmus (HPTAN) are calculated from the EOG. Multiple regression analysis is performed to obtain a the relationship between various nystagmus parameters and BAC; the regression curve can then be used for future estimation of BAC from eye movements.

Synopsis of tracheal sounds

A review is presented of the latest progress in studies of tracheal sounds. In particular, characterization of respiratory and heart-valve sounds to explore and develop automated methods for analysis and diagnosis of pulmonary insufficiency, cardiac, and neurological information is presented. Results from these studies indicate that automated analysis of pulmonary pathology is possible but not without impediments. The mean frequency of respiratory sound spectra is linearly related to respiratory flow rates less than 1 l/s. Respiratory sound spectral estimates are affected by heart-valve sounds, which could adversely affect results of discriminant analysis for patient classification. Static lung volume affects heart-valve sound spectra.<<ETX>>

Localization of current dipole within a sphere by magnetic measurements

The principal objective of this study is the development of computer programs to determine the location and strength of neural electric activity within the brain from noninvasive magnetic field measurements at the surface of the head. This report presents theoretical calculations and computer programs derived from the method described by Williamson and Kaufman to determine the depth and strength of a current dipole in a sphere. From the location of the magnetic field radial component extremes, Br maximum and Br minimum, the orientation and location of the current dipole can be determined. The accuracy of the solution is dependent on precise location of of the magnetic field extremes as measured from the surface of a sphere, e.g. the head. To validate the program for locating the dipole, theoretical calculations and computer programs related to the total magnetic field vector resulting from a hypothetical current source within a homogeneous sphere were generated. The errors in calculations of the current dipole depth and strength are presented.

Public attitudes and perception of bio- and biomedical engineering

Bioengineering professionals practice in a wide variety of subspecialties. Their practices vary from cellular engineering to rehabilitation engineering, and from biomaterial/biomechanics engineering to biomedical education. A major part of the bloengineering field is the one represented by the biomedical engineering professionals of which about 10% practice in the clinical engineering subspecialty focusing on issues involving utilization of technology in the delivery of health care services. Common to these subspecialties, being part of the bioengineering field, is the application of the concepts and methods of the physical and engineering sciences to enhance the development and deployment of safe and effective medical instrumentation. Like all of the other subspecialties clinical engineering, the applied field of biomedical engineering, faces poor public knowledge and lack of recognition for the contributions their professionals have made thus marking a path to improve the quality of our life. Engineering academia is not faring much better than the lay public in their lack of developing and offering of academic programs that will provide the training and skills needed to prepare these professionals for the challenges and responsibilities they will be facing when practicing in the clinical environment. At the root of this problem are the perception and attitude issues. To better understand these attitude and behavior issues we reviewed literature and conducted opinion surveys. In recent years, bioengineers, biomedical, and clinical engineering fields have sought an identity to define their profession. Like many other young professions, bio/biomedical engineering has encountered a professional identity crisis that presents more questions than answers. One issue in defining a profession is the presentation of some clearly illustrated assets and abilities supported by a formal education or accreditation requirements to a targeted customer. In other words, biomedical engineers must define who they are, what they profess to know, and what function they serve to many customers of which the important one is the general public.

Spectral correlates of the averaged auditory evoked response with simulated hematomas and increased Intracranial pressure

In this study, power spectral estimates of the auditory evoked potentials (AEP) and peak latencies were used to predtet Intracranial pressure. Data previously collected from 12 white New Zealand rabbits were used In the study. Descriptive parameters were extracted from power spectra of the AEP, and multiple recession analyses were performed to determine the relationship between ICP and AEP special parameters. Results yield recession models of either time domain parameters (peak latencies) or frequency domain parameters (spectra)that correlate with R-square values of 0.608 and 0.758, respectively, to ICP; however, a model based on combining time domain and frequency domain parameters was the better predictor.

Evaluation of auditory evoked potentials in white New Zealand rabbits with simulated subdural hematoma and increased intracranial pressure

Development of a noninvasive intensive care system calls for the use of evoked potentials (EPs), as a means of diagnosing traumatic head-injured patients. The experiment entails surgically placing two subarachnoid bolts and a subdural balloon through the skull to simulate a subdural hematoma. Using various levels of ICP and/or different sizes of balloons, auditory evoked potentials (AEPs) were recorded from a rabbit. Six positive peak latencies (P1-P6) and five negative peak latencies (Nl-N5) were extracted from an averaged AEP waveform. Multiple regression analyses were performed for determining a relationship between the ICP and AEP peak latencies. The results indicate that a major correlation of changes on AEP peak latencies is due to mechanical forces of a mass (inflated balloon simulating a hematoma) in the distortion of the brain matter rather than increased ICP.

Ocular Tracking Responses To Pseudorandom Stimuli

Human vestibulo-ocular system is known to be nonlinear, however, linear methods are often used in analyze of ocular tracking results. The sum-of-sinusoids method [l] is used to study linear and nonlinear optokinetic responses of human subjects. Nonlinearity of the ocular system is detected by the occurrence of interaction frequencies in the power spectrum of the processed optokinetic response.