Evaluation of the validity of three MABIS blood pressure monitors.
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Blood Pressure↗
Biomedical subjects
Neal S Latman
Publications and source records attributed to Neal S Latman.
A calibration study of therapeutic ultrasound units.
BACKGROUND AND PURPOSE: Physiological effects of therapeutic ultrasound (US) are dependent on the intensity and duration of application. The purpose of this study was to test US machines used in clinical settings for proper calibration of time and power output. METHODS: Measurements of power output and timer accuracy were obtained from 83 US units in clinical use. The machines were tested at 4 intensity settings (0.5, 1.0, 1.5, and 2.0 W/cm2) using a continuous waveform and a 1-MHz frequency. The measured intensities were converted to percentages of error and compared with the +/-20% standard. RESULTS: Of the machines tested, 32 (39%) were outside the calibration standard for at least one output setting. Of these machines, 15 (18%) were above the +20% standard, and 17 (21%) were below the -20% standard for at least one output setting. Of the 32 machines outside the standard, 26 (31%) were outside the standard for 2 or more settings, and 3 (4%) produced no output at any of the settings. Of the mechanical timers tested, 7 (28%) were outside of the +/-10% standard for timer accuracy at the 5-minute interval, and 6 (24%) were outside of the standard at the 10-minute interval. All digital timers tested were within the standard. DISCUSSION AND CONCLUSION: More than one third of machines tested in this study were outside the standard for power output, and approximately one fourth of the mechanical timers were outside the standard. Therefore, further improvements in the accuracy of US machine calibration are needed.
Equipment Design↗
Clinical thermometry: possible causes and potential solutions to electronic, digital thermometer inaccuracies.
Previous research has indicated that the improvements in safety, speed, and ease of use of the newer electronic, digital oral and tympanic clinical thermometers have been offset by a loss in accuracy and reliability when compared with the traditional glass/mercury oral clinical thermometers. The purpose of this study was to determine possible causes of the relative lack of accuracy and reliability in these thermometers and suggest logical potential solutions. Evidence has been reviewed, which suggests that problems with the tympanic thermometers are the result of the range of normal anatomical variability. The combination of an otoscope with the tympanic thermometers is suggested and discussed as a potential solution. Evidence has been reviewed, which suggests that problems with the newer oral thermometers are the results of the size of the temperature sensors and the speed with which they respond. The small sensor size results in variability in placement relative to the primary heat source. The speed of sensor response results in too great a sensitivity to local, acute vasomotor activity (clinical temperature noise). Potential solutions, including an increase in sensor size and a reduction in response speed are discussed.
Body Temperature↗
Evaluation of body composition methods for accuracy.
The objective of this study was to evaluate the accuracy of a variety of portable methods and instruments used to estimate body composition or percentage body fat (%BF) in a systematic, comprehensive manner on a wide range of subjects. The %BF was estimated using four skinfold protocols, three girth measurement protocols, two bioelectric impedance analysis (BIA) instruments, and one near-infrared instrument on 121 subjects. The subjects ranged in age from 21 to 51 years; weight ranged from 105 to 226 pounds and %BF from 8.3% to 38.3%; and the group was 29% male. The %BF estimates were compared to the values obtained from the generally accepted reference standard, underwater weighing (UWW). The correlation coefficients (r) between the test methods and UWW ranged from 0.48 to 0.72. Regression analysis resulted in a range of slopes from 0.48 to 0.93, y-intercept range from 3.8 to 13.1, and standard error of the estimate range from 3.8 to 7.5. All of the methods tended to overestimate lower and underestimate higher %BF. With two exceptions, all methods appeared more accurate for males than females. In general, the near-infrared appeared least and BLA appeared most accurate. In conclusion, in our opinion, most of the methods were not sufficiently accurate to use on a wide range of individuals. Although they may be sufficiently accurate on the narrow sample of subjects on which they were developed, they may not be as accurate for the general population.
Adult↗