Individual differences and the reliability of 2F1-F2 distortion-product otoacoustic emissions: effects of time-of-day, stimulus variables, and gender.

Distortion product otoacoustic emissions (DPOAEs) measured from the ear canal can be a sensitive tool to detect changes in cochlear function over time. However, if multiple-measurement procedures are to be useful clinically, testing needs to be reliable and sources of variability within individuals should be known. Herein, the influence of time-of-day (TOD), stimulus frequency, stimulus sound pressure level (SPL), and gender were evaluated on 2f1-f2 DPOAE amplitude in 16 adult volunteers with normal hearing. The effects of oral temperature and resting-pulse rate were also assessed. This study demonstrated a TOD main effect, with a period approximating one cycle-per-day. The magnitude of this effect averaged less than one dB and was not dependent on stimulus (frequency or SPL) or participant variables (gender, oral temperature, or resting-pulse rate), nor was it synchronized to a particular point-in-time. Stimulus level and gender effects on DPOAEs across frequency were also observed. Using generalizability theory (GT), DP iso-level/frequency profiles (DPILFPs) were found to be reliable measures within-subjects over a contiguous 24-hour time period. Significant and reliable between-subject differences were also documented. This study demonstrates the influence of stimulus and participant variables, quantifies the within-subject reliability over a 24-hour time period, and confirms that significant and reliable between-subject differences exist on DPOAEs across frequency, SPL, and gender.

Biomechanical performance of cardiovascular needles.

Standardized reproducible tests have been developed to determine the biomechanical performance of cardiovascular needles. The parameters used to assess performance were sharpness, resistance to bending, and ductility. Three comparable groups of taper point cardiovascular needles were selected from different manufacturers for these biomechanical studies. The results of this testing demonstrated that needle geometry, needle composition, and the manufacturer were important determinants of needle performance. When needles of comparable size were evaluated, the biomechanical performance of cardiovascular needles manufactured by Ethicon, Inc., were superior to needles produced by other manufacturers. The superior performance characteristics of the cardiovascular needles produced by Ethicon, Inc., were related to their unique stainless steel alloy, American Society for Testing Materials 45500, which has greater yield and tensile strengths than the alloy used by the other manufacturers. Scanning electron microscopic photographs of the Ethicon, Inc., needle revealed a uniform taper point geometry without irregularities. The deformations of the points of cardiovascular needles produced by the other manufacturers could alter their performance.

A beveled, conventional cutting edge surgical needle: a new innovation in wound closure.

A new beveled, conventional cutting edge needle has been developed with superior performance characteristics over those of other conventional cutting edge needles. It is composed of a unique stainless steel, ASTM 45500, that has been heat-treated after the curving process to enhance its resistance to bending. The angle of presentation of its cutting edges has been decreased to enhance needle sharpness. On the basis of the results of experimental and clinical investigations, this new needle is recommended for closure of lacerations.

Emergency medicine magnifying loupes.

A magnifying loupe system has been evaluated for use in emergency medicine. Physicians uniformly preferred a Keplerian lens system over that of the Galilean lens system. The advantages of the Keplerian lens were its increased field of view and its brighter and clearer peripheral image. The Keplerian loupes allowed the physician to visualize the exquisite details of wound configuration and to perform wound closure using microsurgical techniques.

Water treatment of hydrotherapy exercise pools.

The major objectives of water treatment of hydrotherapy pools are to disinfect the water and to balance the water appropriately. A variety of disinfectant systems utilizing either halogens, ozone, or metals have been implemented in hydrotherapy pools. Regardless of the disinfectant system employed, continual and appropriate monitoring of the system is mandatory to prevent infection. Water balancing refers to the control of the water mineral concentration so that the water does not damage the pool. Five major factors that influence water balance are pH, total alkalinity, calcium hardness, total dissolved solids, and temperature. The extent to which these five factors affect water balance can be computed by the Langelier saturation index.