Biomedical subjects

D Eilers

Publications and source records attributed to D Eilers.

4 recordsLinked to original sources

PubMed2001

Intraocular pressure measurement at the choroid surface: a feasibility study with implications for implantable microsystems.

AIMS: To demonstrate that a sensor, which is inserted through the sclera and placed in intimate contact with the choroid, can reliably detect changes in the intraocular pressure (IOP). METHODS: A manometer was used to control the IOP of three cadaver eyes in steps of 7 mm Hg. A piezoresistive pressure sensor was used to measure the pressure at the choroid through a 2.5 mm diameter hole that was surgically removed from the sclera. Data were collected for two configurations; with the sensor: (i) rigidly attached to a miniature positioning stage, and (ii) sutured to the sclera. RESULTS: Both configurations accurately tracked the manometer pressure from 10 mm Hg to 47 mm Hg. For the fixed sensor cases, the average difference between the pressure measured at the choroid and in the anterior chamber was 0.8 mm Hg for the three eyes. For the sutured sensor case, the average difference was 2.1 mm Hg-although a significant portion of this was attributed to an initial offset. The standard deviations at each pressure level for all of the choroid measurements were under 1.0 mm Hg. CONCLUSIONS: Small changes in IOP can be accurately measured by a sensor in contact with the surface of the choroid, for both a fixed sensor configuration and for a sensor sutured to the sclera. These results are the first step in the realisation of a surgically implantable microsensor to monitor IOP for patients suffering from low tension and other difficult to manage forms of glaucoma.

Choroid↗

PubMed2001

Reliability of counting actinic keratoses before and after brief consensus discussion: the VA topical tretinoin chemoprevention (VATTC) trial.

OBJECTIVE: To assess the reliability of counts of actinic keratoses (AKs) and the effect of a brief joint discussion of discrepancies on that reliability. DESIGN AND INTERVENTION: Seven dermatologists independently counted AKs on the face and ears before and after a brief joint discussion of discrepancies. SETTING AND PATIENTS: A volunteer sample of 9 patients from the ongoing VA (Department of Veterans Affairs) Topical Tretinoin Chemoprevention (VATTC) Trial. All participating individuals are veterans and have had 2 or more keratinocyte carcinomas (basal or squamous cell carcinoma) in the 5 years before enrollment in the study. MAIN OUTCOME MEASURE: Standard deviation of estimates of the Poisson regression parameter for the dermatologists. RESULTS: Substantial variation was found among the dermatologists in their AK counts. The SD of the parameter estimates for the dermatologists decreased from 0.45 to 0.24 after the brief joint discussion, a 47% decrease (P =.076). The variation attributable to the dermatologists also decreased substantially (chi(2)(6) decrease, 94 to 12). CONCLUSIONS: Actinic keratoses are common, and there is a continuous spectrum of lesions that ranges from sun-damaged skin to squamous cell carcinoma in situ. Clinical distinguishing features may be difficult to delineate precisely. Counts of AK are commonly performed, but appear to be unreliable, even when performed by experienced dermatologists. Joint discussion of discrepancies may enhance the reliability of these counts, although substantial variation remains. Research that relied on these counts must be reevaluated in light of the marked variation among expert observers. Future studies should consider measures to assess and enhance reliability.

Aged↗

PubMed1996

[Ultrasound scalpel--initial experiences with use in laparoscopic surgery].

Worldwide the use of monopolar electrocautery is preferred in laparoscopic surgery. Beside the risk of thermal injury the technique involves some inconveniences for the surgeon. The ultrasonic scalpel offers theoretical advantages, which were clinically studied in a series of 443 operations. The absence of smoke, the reduced need for cleaning of the optic and the lack of complications due to the device lead us to believe that the ultrasonic scalpel is superior to electrocautery especially for beginners in laparoscopic surgery. The costs of the system--DM 150 per patient in our prospective series--are tolerable.

Blood Loss, Surgical↗

PubMed1982

Low-gravity environment in Spacelab.

This paper presents residual and system-generated accelerations with results from g-jitter spectral measurements in the Spacelab Engineering Model. An overview (classification, brief discussion, and assessment of magnitudes) of the various constituents of the perturbative acceleration field inside the Spacelab Module is presented, both steady and fluctuating components being considered. Results of local g-jitter spectral measurements taken in the Spacelab Engineering Model (EM-1)/Long Module Configuration are presented for frequencies from less than 1 to 200 Hz. The measured results for the system-generated perturbative accelerations exhibit, in the time domain, amplitudes of the order of 10(-3) g (peak value 3.6 x 10(-3) g). Spectral values of 4 x 10(-4) g are obtained in the frequency range up to 100 Hz; up to 10 Hz, however, the spectral values remain about an order of magnitude smaller, and also between 100 and 200 Hz the perturbation level is significantly lower than below 100 Hz. Measured results from simulated crew activities show, in the time domain, a peak amplitude of 2.6 x 10(-2)g, the spectral values being 6 x 10(-3)g below 100 Hz and 1 x 10(-3)g below 10 Hz for typical perturbances.

Acceleration↗