Neal S. Latman

Bioelectrical impedance analysis determination of water content and distribution in the horse.

A horses hydration status is critical to its health. The accurate and quantitative determination of it has been problematic because of size, length and density of hair, and uneven topography. The objective of this study was to validate a bioelectrical impedance analysis (BIA) method for objectively quantifying hydration status. Monofrequency BIA values and simple biometric measurements were used to construct predictive equations for total body water, plasma, extracellular, and intra-cellular fluid volumes. These predictive equations were correlated with standard body fluid dilution reference methods. The result was an accuracy of ±0.64% for total body water, ±0.17% for plasma volume, ±1.91% for extra-cellular fluid, and ±0.57% for intra-cellular fluid compartments. Less than 5 min was required for all of the measurements and determinations. Therefore, it appears that an accurate measurement of body fluid distribution can be performed on horses using a fast, easy, non-invasive, inexpensive BIA method.

A field study of the accuracy and reliability of a biometric iris recognition system

PURPOSE The iris of the eye appears to satisfy the criteria for a good anatomical characteristic for use in a biometric system. The purpose of this study was to evaluate a biometric iris recognition system: Mobile-Eyes™. METHODS The enrollment, verification, and identification applications were evaluated in a field study for accuracy and reliability using both irises of 277 subjects. Independent variables included a wide range of subject demographics, ambient light, and ambient temperature. A sub-set of 35 subjects had alcohol-induced nystagmus. There were 2710 identification and verification attempts, which resulted in 1,501,340 and 5540 iris comparisons respectively. RESULTS In this study, the system successfully enrolled all subjects on the first attempt. All 277 subjects were successfully verified and identified on the first day of enrollment. None of the current or prior eye conditions prevented enrollment, verification, or identification. All 35 subjects with alcohol-induced nystagmus were successfully verified and identified. There were no false verifications or false identifications. Two conditions were identified that potentially could circumvent the use of iris recognitions systems in general. CONCLUSIONS The Mobile-Eyes™ iris recognition system exhibited accurate and reliable enrollment, verification, and identification applications in this study. It may have special applications in subjects with nystagmus.

Evaluation of Validity of the PMI FIT 2000-3 Fitness-for-Duty/Impairment Screener

Eye reflex measurements have been suggested as a means of identifying the risk of fatigue due to sleep deprivation. The PMI FIT 2000-3 Fitness-for-Duty/Impairment Screener was developed to classify subjects as low risk or high risk for fatigue based on the comparison of 4 eye reflex measurements (pupil diameter, constriction amplitude, constriction latency, and saccadic velocity) to rested baseline values. The purpose of this experiment was to determine the validity of the PMI FIT 2000-3, where validity was defined as the classification of subjects as high risk following 48 hours of sleep deprivation. In the week before the test period, 12 subjects were tested at least 10 times after a typical, full nights rest to establish baseline values. Subjects were then tested 3 times every 4 hours during 48 hours of sleep deprivation. No subjects were classified as high risk at the end of the test period, and none were classified as high risk at any point during the 48 hours without also being classified as low risk at the same time. Ultimately, the PMI FIT 2000-3 was not found to be a valid measure of fatigue resulting from sleep deprivation.

Accuracy, Reliability, and Human Factors Associated With Self-Monitoring of Blood Glucose

Most morbidity and mortality associated with diabetes mellitus (DM) is due to hyperglycemia. Self-monitoring of blood glucose can be accomplished using a portable blood glucose monitor. If accurate, the results can be used in the management of DM. The purpose of this study was to evaluate the accuracy, reliability, and human factors of the following portable blood glucose monitors: One Touch Ultra, Precision Xtra, Prestige Smart System, Freestyle Flash, and Glucometer Dex 2. Accuracy was determined at 5 concentrations of blood glucose in a Sugar Chex Linearity reference standard and at 4 concentrations in subject blood. Reliability was determined by 5 repeat measurements on each of 5 reference standards by 14 individuals which provided intra- and interuser variability. A 10-item human factors questionnaire was completed by 14 users on each monitor. Instrument accuracies, defined as ±10% of reference value as recommended by the American Diabetes Association, ranged from an overall average of 62% to 10% of individual measurements on the reference standard. Instrument accuracies ranged from 75% to 25% on individual measurements on the human subject blood. Reliability, expressed as a coefficient of variation, ranged from 4% to 8%. The One Touch Ultra was rated/ranked highest overall for human factors. In conclusion, the test monitors appeared relatively reliable, but did not appear to exhibit sufficient accuracy to satisfy the American Diabetes Association recommendations. A wide range of accuracies and human factors was found. Some of these monitors may not be sufficiently accurate for DM management.

Drug Delivery Properties of Six Nebulizer Systems

Objectives—nebulizers offer quick and efficient drug delivery to the lungs. The purpose of this study is to characterize six nebulizer systems. Some important aspects of nebulization studied are drug content and concentration, reservoir solution temperature during nebulization, and nebulization time. Methods—four jet nebulizer-compressor systems, with the same jet nebulizer model, and two ultrasonic nebulizer systems were characterized in this study. Drug content/concentration for each nebulizer was analyzed with two concentrations (1.25 and 0.63 mg) of albuterol sulfate. UV/visible spectrophotometry was utilized to determine reservoir drug content and concentration. Reservoir temperature measurements were taken with a temperature probe. Results—for the 1.25-mg dosage form of the drug, the compressor-driven systems had the least amount of decrease in reservoir drug content while the ultrasonic nebulizer had the greatest amount of decrease in reservoir drug content. All of the nebulizers, except for one compressor-driven system, had equivalent amounts of drug remaining in the reservoir for the 0.63-mg drug dosage form. The compressor-driven and ultrasonic systems had an increase in drug concentration for both forms of the drug. However, a decrease occurred in the ultrasonic system with the 0.63-mg dosage form of the drug. The reservoir temperature decreased in most of the compressor-driven systems while the temperature increased in the ultrasonic systems. The quickest nebulization time was seen in the ultrasonic systems. Conclusions—the ultrasonic nebulizer is the most efficient in nebulizing the greatest amount of medication in the least amount of time, while the compressor-driven systems are the least efficient in nebulizing the medication and require a greater nebulization time.

Evaluation of Neuromuscular Electronic Stimulation on Dysphagia: A Case Study

Traditional treatment methods for treating dysphagia, including muscle exercises and compensatory strategies, have limited effectiveness. Neurological swallowing difficulties account for 30% of cases requiring home enteral tube feeding, and only 19% of this return to full oral nutrition in 1 year. One potential treatment solution is the use of neuromuscular electronic stimulation (NMES). The purpose of this study was to evaluate the effectiveness of an NMES device (VitalStim, Chattanooga Group, Hixson, Tennessee) on strengthening the suprahyoidal and infrahyoidal muscle groups used in swallowing. The subject in this case study was an 86-year-old woman with age-associated dysphagia. Treatment with NMES was given during lunch for 45 minutes, 5 days a week for 5 weeks in accordance with the standard VitalStim treatment protocol. Neuromuscular electronic stimulation was increased from 11 to 22 mA over the 5-week period as tolerated by the subject. Effect of treatment on muscle group strength was determined preprandial and postprandial by surface electromyography. Average muscle strength of the suprahyoidal and infrahyoidal muscle groups improved with treatment through the third or fourth week. During the fourth week, the postprandial strengths in both muscle groups reached their peak. During the fifth week, average muscle strength decreased significantly in both muscle groups to pretreatment levels. The cause of the decrease was not clear. Average duration of the pharyngeal phase of swallowing was significantly and progressively lessened over the 5-week period as evidenced by preprandial and postprandial electromyography readings. A shortened pharyngeal phase resulted in client reports of easier swallowing, with less multiple attempts at initiation of swallow.

A Human Factors Evaluation of Stethoscopes

Background: The need to hear sounds of the human body is important in health care. The stethoscope was designed to improve practitioner’s method of “immediate auscultation.” The purpose of this study was to evaluate and compare 16 human factor characteristics of two electrically amplified and one standard acoustic stethoscope. Methods: Each subject examined the three stethoscopes by listening to heart sounds of the investigator. After examination, each of the 77 subjects evaluated the stethoscopes by completing a questionnaire according to the following categories: sound, comfort, ease of use, and instruction manuals. Subjects ranged in age from 18 to 67 years, with 51 % of the subjects having prior experience with stethoscopes. Results: Both electronically amplified stethoscopes were found to have a significant difference in regard to preference compared with the non-electronically amplified standard stethoscope on all characteristics. No significant differences were found between the two electronically amplified stethoscopes, with the exception of turning the stethoscopes on and off. The average mean ratings of the two electronically amplified stethoscopes were not significantly different. Conclusion: It is clear that electronic amplification was preferred over acoustically amplified sound in this study. As the complexity increases with electronic amplification, the importance of ease-of-use design becomes more important.