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PubMed1990

The efficiency of a reflective heating blanket in preventing hypothermia in patients undergoing intra-abdominal procedures.

This study determined the efficiency of a reflective blanket in preventing hypothermia during intra-abdominal gynecological procedures. Forty female patients were studied. A table of random numbers was used to assign patients to the reflective blanket group (experimental) or the warmed cotton blanket group (control). Esophageal and room temperatures were measured. Data were recorded regarding age, height, weight, body surface area, first-hour intravenous fluid volume, time from induction to skin incision and time from skin incision to peritoneal incision. The study showed no significant differences between groups in regard to esophageal or room temperatures (ANOVA, p greater than .05). No significant differences between groups in regard to patient characteristics were found (ANCOVA). No correlation was found between esophageal temperature and room temperature in either group. A significant decrease in esophageal temperatures was found in both groups during the first 45 minutes of the study (p less than .01), after which temperatures stabilized. In conclusion, the reflective blanket was no more efficient than warmed cotton blankets in preventing intraoperative hypothermia. Previous studies showing the greatest decrease in temperature occurred within the first hour of anesthesia and surgery were supported. The reflective blanket may be useful for operating rooms where the storage and heating of cotton blankets is not feasible due to limited space or cost.

Abdomen↗

PubMed1989

Systolic blood pressure: arterial compliance and early wave reflection, and their modification by antihypertensive therapy.

Arterial stiffness (the inverse of compliance) is the major determinant of left ventricular and central aortic peak systolic pressure. Recent prospective epidemiological studies (MRFIT, Framingham) have confirmed the importance of systolic (rather than diastolic) pressure in the development of cardiac failure and stroke, and in all-cause mortality. Arteries stiffen in hypertension and with increasing age. Arterial stiffening increases systolic pressure by two mechanisms. The first is by causing a higher pressure to be generated at the peak of ventricular ejection (through increase in aortic characteristic impedance), and the second is by causing a secondary rise attributable to early return of wave reflection from peripheral sites (through an increase in arterial pulse wave velocity). ACE inhibitors, and also nitrates, decrease arterial stiffness. They also dilate peripheral conduit arteries; this reduces wave reflection. These drugs thus reduce systolic pressure in central arteries not only by reducing arterial stiffness but also by reducing inappropriately early wave reflection. Quantitatively, the latter action seems to be more important than the former. Neither action is seen with beta-blocking agents. These beneficial actions on central systolic pressure are not always apparent when pressure is measured in a peripheral artery such as the brachial or radial. This is because the reflected wave constitutes the peak of the pressure wave in central arteries but is usually just an undulation on the downstroke of the wave in peripheral arteries. Hence sphygmomanometric recordings underestimate reduction in central systolic pressure and in left ventricular load brought about by ACE inhibitors and by nitrates.

Antihypertensive Agents↗

PubMed1989

Precision of reflectance meters in screening for gestational diabetes.

The use of reflectance meters to screen for gestational diabetes has been advocated because of convenience and apparent accuracy. The present study addresses the possibility that imprecision of reflectance meters may affect the reliability of the blood sugar values obtained with their use. We tested four reflectance meters (Glucometer, Glucometer II, Glucoscan 3000, and Accuchek II) on 84 gravidas undergoing 1-hour, 50-g glucose screening, and calculated average coefficients of variation (9.6 +/- 10.9, 8.2 +/- 4.7, 6.8 +/- 4.5, and 7.4 +/- 4.4%, respectively). One-way analysis of variance testing indicated no significant difference between these values (P = .11). However, comparison with the coefficients of variation from standard laboratory technology (YSI Model 23A Glucose Analyzer) applied to simultaneously obtained venous samples (2.3 +/- 1.5, 1.5 +/- 0.6, 1.9 +/- 1.0, and 1.0 +/- 0.5%) revealed that the meters all had coefficients of variation significantly higher (P less than .0001). Use of reflectance meters would have resulted in 45.2% (38 of 84) of the subjects undergoing 3-hour oral glucose tolerance tests. Use of standard laboratory values would have indicated these tests in only 16% (14 of 84). The inconvenience and increased cost of these oral glucose tolerance tests suggest that meters may not be appropriate for screening.

Blood Glucose↗

PubMed1986

Separation of the reflection by the inner limiting membrane.

A ray incident upon the inner limiting membrane is specularly reflected, whereas the other retinal structures reflect light diffusely into large solid angles. Thus by moving a small diaphragm inside the exit pupil, it is possible to separate the component of the reflected light which originates at the inner limiting membrane. To check that this light added to the aerial image is not caused by the specular reflection from an anterior surface (cornea or lens), interference fringes were projected onto the retina, and their modulation depth was measured in the plane conjugate with the retina: since the inner limiting membrane and the anterior media were the sources of modulated and unmodulated aerial images respectively, their contributions could be separately measured.

Adult↗

PubMed1979

Diffusion permeability and ultrafiltration-reflection-coefficients of Narand Cl- in the near-term placenta of the sheep.

Experiments were performed on unanaesthetized ewes in the last third of pregnancy. Fetuses and ewes had indwelling vascular catheters. In some of the experiments fetal urine was drained to the exterior by means of an indwelling vesicular catheter. Placental diffusion permeabilities were measured with 22Na+ and 36Cl- injected into eight fetuses. Volumes of distribution of Na+ and Cl- in the conceptus were Na+: 548 +/- 24, Cl-: 760 +/- 51 (ml/kg fetal wt +/- SEM). Diffusion permeabilities were Na+: 5.2 X 10(-3) +/- 0.3 X 10(-3), Cl-: 9.8 X 10(-3) +/- 0.9 X 10(-3) (ml.s-1.kg-1 +/- SEM). Ultrafiltration-reflection-coefficients of Na+ and Cl- in the placental exchange barrier were measured 17 times in seven fetuses with vesicular catheters. The transplacental e.m.f. was estimated from these results, on the assumption that the individual reflection-coefficients of Na+ should correlate with those of Cl-. The best estimate was -1.0 mV (fetus negative), and the best estimates of the placental reflection-coefficients were Na+: 0.83 and Cl-: 0.79. There was a reliable negative correlation (P < 0.01) between the calculated reflection-coefficients and the osmolality of the urine secreted by the fetus. This suggested that the concentration of vasopressin in fetal plasma affects the membrane characteristics of the placenta. The mean total osmotic force across the placental barrier of the sheep in these experiments was calculated to be 260 Pa (2 mmHg).

Animals↗

PubMed1995

The use of reflection to enhance practice.

Reflection enables learning to occur from immediate experiences, from which theory and frameworks of care can be developed. Reflection heightens self-awareness, enabling increased understanding of the effects that past experiences may have on care delivery. Personal and professional development occurs through the process of reflection. Kolb's experiential learning theory provides a framework for reflection, focusing on the role of experience in learning.

Clinical Competence↗

PubMedDate not supplied

Kubelka-Munk reflectance theory applied to porcelain veneer systems using a colorimeter.

The purpose of this study was to demonstrate the ability of Kubelka-Munk reflectance theory to predict color parameters of veneer porcelain on various backings using colorimetric measurements. Tristimulus absorption and scattering coefficients were used to predict the respective tristimulus reflectance values of A1, D3, and translucent porcelain samples after they had been bonded to light and dark substrates using universal, opaque, and untinted shades of bonding resin. Observed and predicted reflectance values exhibited high correlation (r2 > or = 0.93 for each porcelain shade). Kubelka-Munk theory offers an accurate prediction for the resultant colorimetric reflectance parameters of veneer porcelain bonded to variously colored backings.

Absorption↗

PubMed1994

Computational principles in Purkinje I and IV reflection pattern evaluation for the assessment of ocular alignment.

PURPOSE: To develop a standardized reasoning for the evaluation of Purkinje I and IV Reflection Pattern data in primary, secondary, and tertiary positions of gaze in the diagnosis of strabismus with a mathematical approach. To demonstrate the applicability of certain mathematical relations and the appropriate graphic representation of computed ocular alignment data. METHODS: Starting from the known Reflection Pattern Evaluation formulae, equations were derived that allowed for the computation of the relative and absolute positions of the optical and visual axes of both eyes from original data in binocular and monocular fixation. These equations were simplified for clinical use. RESULTS: The authors obtained a set of equations that could be applied to the objective, quantitative analysis of eye alignment in screening for microtropia, in concomitant and incomitant diagnoses of strabismus in primary and nonprimary positions. CONCLUSIONS: Purkinje I and IV Reflection Pattern Evaluation can be extended to the diagnosis of strabismus in nonprimary positions with sufficient clinical accuracy. The newly presented principles and equations serve as a basis for a convenient graphic representation of Purkinje I and IV Reflection Pattern data. These principles of evaluation may be applied to any data dealing with ocular alignment, independently of the method.

Afterimage↗

PubMed1994

Fostering learners' reflection and self-assessment.

In most medical schools and residency programs, little or no attention is given to fostering learners' reflection or self-assessment. Yet learners who do not value or who are not effective at these skills are unlikely to extract the maximum benefit from their education. They are at risk of becoming unsafe physicians. To be optimally helpful, teachers need access to the diagnostic information about learners that is provided by their reflections and self-assessments. There are major barriers to learners being reflective and self-assessing. Medicine is dominated by unreflective doing. In the fiercely competitive environment of many teaching programs, many learners correctly perceive that it is unsafe to reveal their fears and deficiencies. Learners often retain this cautious posture even after moving to programs where it is unnecessary. Many learners and teachers have grown accustomed to authoritarian educational approaches in which teachers decide what the learners need and unilaterally evaluate their performance. In this review of the available literature, we summarize the compelling reasons for fostering reflection and self-assessment and for helping learners become their own coaches. Specific strategies and tools for creating programs that foster these values and activities are presented.

Clinical Competence↗

PubMed1993

Interpreting peritoneal membrane osmotic reflection coefficients using a distributed model of peritoneal transport.

The relationship between the osmotic reflection coefficient for the peritoneal membrane and that for peritoneal capillaries was derived theoretically using a distributed model of peritoneal transport. The distributed model predicted that the osmotic reflection coefficient for the peritoneal membrane was equal to that for peritoneal capillaries only when the capillary wall was the dominant diffusive solute transport resistance. Under these conditions, moreover, all peritoneal capillaries equally contributed to transperitoneal ultrafiltration. If, on the other hand, interstitial tissue was the dominant diffusive solute transport resistance, then the osmotic reflection coefficient for the peritoneal membrane was lower than that for peritoneal capillaries and only superficial capillaries participated in transperitoneal ultrafiltration. Previous experiments have demonstrated that the capillary wall is not the dominant diffusive solute transport resistance for small osmotic solutes across the peritoneal membrane; thus osmotic reflection coefficients for the peritoneal membrane are likely several times less than those for peritoneal capillaries.

Biological Transport↗

PubMed1994

[Who benefits from systemic therapy with a reflecting team?].

In an evaluation study we investigated the effectiveness of the reflecting team approach compared to eclectic child psychiatric treatment in an outpatient setting and the indications for each type of treatment. The relationship between treatment outcome and diagnostic data obtained with the Multi-axial Classification Scheme was examined in 22 families treated with the reflecting team approach and in a second group of families matched on all important sociodemographic and diagnostic variables but receiving eclectic treatment. No difference was found between the two groups regarding symptom improvement or changes in family functioning. Regarding satisfaction with treatment, the reflecting team approach was superior to the eclectic modality. In the reflecting team group parental mental disorder and inadequate intra-familial communication (according to the new fifth axis of the Multi-axial Classification Scheme) had a negative effect on outcome.

Adolescent↗

PubMed1995

[Reflection measurement during retinal laser coagulation in patients. Development of an automatically controlled dosimeter].

PURPOSE: Retinal laser coagulation has limited reproducibility, because every laser exposition is unpredictably affected by pigmentation and media opacities. This can lead to complications. A feedback-controlled dosimeter would make retinal laser treatment a safer, more reproducible and faster procedure. METHOD: A reflectometer was developed that allows monitoring of the reflection of laser light during standard photocoagulation. Hundreds of coagulations in rabbit eyes and about 12,000 coagulations in patients undergoing routine laser treatment were recorded. RESULTS: The results of the first reflectance measurements in humans are presented along with extensive animal studies. A typical reflectance history was found for different lesion intensities. The degree of retinal whitening correlates with reflectance characteristics. These characteristics allow an early prediction of lesion intensity. Motion during laser exposure affects each coagulation in a fashion similar to spot size and exposure time. CONCLUSION: Reflectometry is the currently most effective means of monitoring lesion development. An automatic dosimeter for retinal photocoagulation seems feasible.

Animals↗

PubMedDate not supplied

How the Burford reflective model boosts care standards.

Reflective practice is grounded in the practitioner's everyday experiences. This is why this second part of an examination of reflective models of nursing considers the experiences of two nurses who used the Burford reflective model to inform and refine the care they offer. One reflects on a routine series of community visits, the other focuses on the drama and distress surrounding a terminal illness.

Community Health Nursing↗

PubMedDate not supplied

How the Burford reflective model boosts care standards.

Aged↗

PubMed1996

Multiple fluorescence and reflectance simultaneous detection by confocal microscopy of HaeIII digested DNA sequences.

Human metaphase chromosomes were isolated and digested in situ with HaeIII restriction enzyme to detect cytosine and guanine-rich sequences (CpG islands), which are known to be associated with most of the mammalian genes. Digested DNA was reconstructed by in situ nick translation employing digoxigenin-labeled nucleotides. The DNA sequences were revealed by antibodies conjugated either with fluorescein isothiocyanate or 1-nm colloidal gold. DNA was counterstained with propidium iodide. A sensitive, high resolution method for visualizing three signals, simultaneously excited by a single argon laser line of 488 nm has been developed. The green fluorescence of fluorescein isothiocyanate was detected in combination with the red fluorescence of propidium iodide, and the third signal was imaged by employing the reflectance mode of the confocal microscope after silver enhancement of the gold beads. The high reflectance intensity, the accurate localization and the non-fading properties of colloidal gold made the reaction a valuable tool for the detection of antigens and, as a consequence, of specific DNA sequences in chromosome preparations. Overlaying of three signals allowed the simultaneous observation of distinct structures: total DNA, as well as fluorescein- and gold-labeled sequences after in situ nick translation, or total DNA and centromeric sequences of two different chromosome pairs (17 and X) after in situ hybridization. The use of HaeIII restriction enzyme that cut CpG islands combined with in situ nick translation identified the chromosome sites where active, inactive or housekeeping genes can be located. In chromosomes, the fluorescent reaction pattern showed large areas of labeling, while a more defined staining, often organized in spot pairs that resembled an R-like banding, was detected when the reflected mode was used. These results are confirmed by the observation that R-like bands actually are multiple symmetrical spots localized on sister chromatids. In addition, some chromosomes, and in particular 1 and 9, displayed a C-negative banding due to the negativity of the centromeric areas. Reflectance confocal scanning microscopy and in situ nick translation represent a powerful tool to study the in situ genome organization.

Chromosomes, Human↗

PubMed1996

Reflecting on clinical practice: hectoring talk or reality?

Reflection can be seen as a useful tool to enable the practitioner to explore the everyday world of clinical practice. This paper reviews the background to reflection and its relevance to nursing in reducing the theory--practice gap and its role in generating theory from practice. Exemplars from clinical practice are reflected upon and Carper's (1978) 'Patterns of Knowing' are used as a framework to identify nursing knowledge embedded in practice. The process of reflection is critically discussed in the light of the author's experience.

Humans↗

PubMed1997

Visual performance and patient preference: a comparison of anti-reflection coated and uncoated spectacle lenses.

BACKGROUND: Anti-reflection (AR) coatings of spectacle lenses are designed to reduce the reflected images often found in uncoated lenses. This study examined the visual impact of a specific AR coating. METHODS: First, using a survey, it was determined if patients were aware of the AR coating and, if given an identical pair of lenses without the AR coating, which lenses were preferred and why. Second, in the laboratory, changes in visual performance were evaluated when an anti-reflection coating was applied to a lens. RESULTS: Verbal reports were obtained from 18 patients on both types of lenses. All patients were aware the AR coating reduced unwanted reflections, and many reported reductions in visual problems associated with glare. Within the laboratory, 28 patients were tested on a battery of clinical vision tests. Under normal room illumination, visual acuity, grating-contrast sensitivity, and letter-contrast sensitivity were identical for both coated or uncoated lenses. In a second experiment, the effects of AR coating on contrast sensitivity were examined when subjects viewed a dimly illuminated target while their eye and face were brightly illuminated. Under these conditions, significantly better (a factor of two) contrast sensitivity was observed with AR-coated lenses. CONCLUSIONS: On the basis of these findings, it is proposed that drivers should wear AR-coated spectacle lenses at night.

Adult↗

PubMed1999

Total internal reflection of laser light in eyes filled with silicone oil.

BACKGROUND AND OBJECTIVES: This is the first report of clinical settings in which total internal reflection of laser light in eyes filled with silicone oil was observed. The authors analyze this phenomenon and outline the potential hazards it may present to patient, surgeon, and operating room personnel. MATERIALS AND METHODS: The authors observed significant reflection of laser light off the silicone-water interface both intraoperatively and in the clinic. The critical angle according to Snell's law (i.e., the angle at which total internal reflection occurs at the interface between silicone oil and vitreous) was calculated. The critical angle was found to be 71.9691 degrees(72 degrees). RESULTS: An analysis of each of the clinical conditions where this phenomenon was observed is presented. Clinical and surgical implications are discussed. CONCLUSIONS: The hazard of total internal reflection of laser light in eyes filled with silicone oil should be recognized by ophthalmologists to avoid possible complications. Techniques for overcoming and circumventing the difficulties resulting from this phenomenon are proposed.

Humans↗