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Results for “corrective measures”

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PubMed1982

[On some experimental conditions possibly influencing the correct measurement of venous pressure by Doppler method].

Measurement of venous pressure by means of the Doppler method applied to the posterior tibial vein and to the internal and external saphenous veins is subject to error which depends on the observer's technique. We have therefore sought to ascertain whether and how differences in measurement techniques could affect the results of venous pressure determination in 50 subjects. We have observed that: --Measured pressure are higher when the duration of the test is prolonged, probably because the cuff remains inflated too long. --Of several consecutive determinations, the first and second yield generally higher values, that decrease and remain stable thereafter through the 5th measurement, following the initial loss of venous tone. --Venous pressure is lower as the measurement site is moved more proximally, as predicted by the expected pressure gradient along the venous circulation; the decrease could also be affected by local changes of vein compliance.

Adult↗
PubMed2006

[Feasibility of prismatic correction of microesotropia using the measuring and correcting methodology by H.-J. Haase].

BACKGROUND: The "Measuring and Correcting Methodology after H.-J. Haase" is based on the assumption that a minute deviation from the orthovergence position (fixation disparity) indicates a difficulty to overcome a larger "vergence angle of rest". Objective recordings have, however, revealed that the subjective tests applied in the "Measuring and Correcting Methodology after H.-J. Haase" can mislead to the assumption of a fixation disparity, although both eyes are aligned exactly to the fixation point. QUESTION: How do patients with an inconspicuously small, yet objectively verified strabismus react to the "Measuring and Correcting Methodology by H.-J. Haase"? METHODS: Eight patients with a microesotropia between 0.5 and 3 degrees were subjected to the "Measuring and Correcting Methodology after H.-J. Haase. RESULTS: In all 8 patients, the prisms determined with the Cross-, Pointer- and Rectangle Tests increased the angle of squint, without reaching a full correction: the original angle prevailed. In the Stereobalance Test, prisms did not reduce the 100 % preponderance of the non-squinting eye. The stereoscopic threshold was between 36 and 1170 arcsec in 7 out of the 8 subjects, and above 4000 arcsec in 1 subject. CONCLUSIONS: (1) In all 8 patients, prisms determined with the "Measuring and Correcting Methodology by H.-J. Haase" increased the angle of strabismus, without reaching bifoveal vision. This uniform result suggests that primary microesotropia cannot be corrected with the "Measuring and Correcting Methodology after H.-J. Haase" (2) A lacking contribution of the strabismic eye to the recognition of a lateral offset between stereo objects, as determined with the Stereobalance Test, does not imply a lack of binocular stereopsis.

Adolescent↗
PubMed2005

Correlated errors in biased surrogates: study designs and methods for measurement error correction.

A measurement error model proposed previously allows for correlations between subject-specific biases and between random within-subject errors in the surrogates obtained from two modes of measurement. However, most of these model parameters are not identifiable from the standard validation study design, including, importantly, the attenuation factor needed to correct for bias in relative risk estimates due to measurement error. We propose validation study designs that permit estimation and inference for the attenuation factor and other parameters of interest when these correlations are present. We use an estimating equations framework to develop semi-parametric estimators for these parameters, exploiting instrumental variables techniques. The methods are illustrated through application to data from the Nurses' Health Study and Health Professionals' Follow-up Study, and comparisons are made to more restrictive models.

Bias↗
PubMed1997

Can training improve the results with infrared tympanic thermometers?

BACKGROUND: Infrared tympanic thermometry (ITT) is a method for body temperature measurement. Correct measuring technique is said to be important to achieve good results with this method. The objective of this study was to investigate the accuracy and effect of training in the use of infrared tympanic thermometry (ITT) on the measurement results. METHOD: Nurses trained in the use of ITT, and nurses not trained performed measurement sequences on 65 patients: one rectal and two ITT measurements in each sequence. RESULTS: Mean rectal temperatures were significantly (P < 0.01) higher than with ITT (0.44 +/- 0.42 (SD) degree C for trained, 0.56 +/- 0.4 (SD) degree C for untrained). Coefficient of repeatability for ITT measurements was +/- 0.54 degree C for trained nurses, and +/- 0.48 degree C for untrained. With ITT temperatures adjusted upwards of 0.5 degree C, the sensitivity of ITT for detecting fever as defined by rectal measurements would be 70% for trained, and 54% for untrained nurses. Repeatability and sensitivity for trained and untrained nurses were not significantly (P > 0.05) different. CONCLUSION: Training had little effect on the accuracy of the measurements. According to our results, ITT is often unreliable and should be used with caution.

Adult↗
PubMed1991

Influence of detector size in photon beam profile measurements.

Correction is necessary to account for the detector size in clinical dosimetry of photon and electron beams. This correction is due to the absorbed dose gradient present in a finite-size detector. Further corrections are necessary when the detector and phantom materials are not the same. These corrections are due to the perturbation in the charged-particle fluence. Generally these corrections are applied to measurements along the central axis of the beam. Cross beam profile measurements, however, are not usually corrected for detector size. The ionization profile is also usually assumed to be equivalent to the absorbed dose profile. We have corrected the ionization chamber size effect by two approaches: extrapolation of measurements to zero detector size and deconvolution of measurements using a simple model for the detector response function. We have measured absorbed dose profiles to water using a small water-equivalent plastic scintillation detector. Film profile measurements were also studied. The ionization profile corrected for detector size and absorbed dose profile were not equal, probably due to loss of charged-particle equilibrium in the beam edges. For ionization chamber measurements, knowledge of the charged-particle spectrum is needed to convert ionization to absorbed dose to water. This is not necessary for relative absorbed dose measurements under charged-particle equilibrium. Film has been shown to be a straightforward and reliable method for cross beam profile measurements.

Film Dosimetry↗
PubMed2001

[Prospective study of the causes for destruction of labile blood products during 1999 at a University Hospital Center].

The destruction of the blood cell product (BCP) is a situation which is hard to accept in the present context of transfusional safety which aims at covering the transfusional needs in the most appropriate way. In our University Hospital, 500 BCP out of 20,000 are destroyed per year, which represent a cost of 100,000 $. A prospective research was carried out from January 1st to December 31st 1999 in order to analyse the causes of the destruction of the BCP and to differentiate the inevitable destructions for the patient's security from the avoidable destructions which might have benefited from corrective measures. For each group of simultaneously destroyed BCP, an information note specified the patient's pathology, the reasons for the prescription, the number and the type of transfused and destroyed BCP in the same day, the time spent between distribution and return, and the causes of destruction. In 1999, a total of 483 LBP out of 19,802 which were distributed, have been returned and destroyed, that is to say 2.4% for a 99.3% traceability which involved 242 patients. Among these destroyed BCP, 28.3% came from inevitable causes--death or acute intensive care which needed a lot of transfusions--69.7% were categorised as being related to avoidable causes depending on the organisation of transport and care, unadapted safety measures. The corrective measures to be taken, concern the improvement of transport procedures, the set-up of a nominative BCP reservation system in the Blood Center, the scheduling of the BCP deliveries from the blood bank, and a better adaptation of the safety measures to the transfusional needs.

Blood Banks↗