Effects of delayed cord clamping on residual placental blood volume, hemoglobin and bilirubin levels in term infants: a randomized controlled trial.

OBJECTIVE: The objective of the study was to measure the effects of a 5-min delay (DCC) versus immediate cord clamping (ICC) on residual placental blood volume (RPBV) at birth, and hemoglobin and serum bilirubin at 24 to 48 h of age. STUDY DESIGN: In this prospective randomized controlled trial, 73 women with term (37 to 41 weeks) singleton fetuses were randomized to DCC (⩾5 min; n=37) or ICC (<20 s; n=36). RESULTS: Maternal and infant demographics were not different between the groups. Mean cord clamping time was 303±121 (DCC) versus 23±59 (ICC) s (P<0.001) with 10 protocol violations. Cord milking was the proxy for DCC (n=11) when the provider could not wait. Infants randomized to DCC compared with ICC had significantly less RPBV (20.0 versus 30.8 ml kg-1, P<0.001), higher hemoglobin levels (19.4 versus 17.8 g dl-1, P=0.002) at 24 to 48 h, with no difference in bilirubin levels. CONCLUSION: Term infants had early hematological advantage of DCC without increases in hyperbilirubinemia or symptomatic polycythemia.

Umbilical cord milking in term infants delivered by cesarean section: a randomized controlled trial.

OBJECTIVE: The study's objective was to compare hematocrit (Hct) levels at 36 to 48 h of age in term infants delivered by cesarean section exposed to immediate cord clamping or umbilical cord milking (UCM). STUDY DESIGN: In this randomized controlled trial, 24 women scheduled for elective cesarean section were randomized to either immediate clamping (<10 s) or UCM (milked × 5 by the obstetrical provider) at birth. RESULT: All subjects received their allocated intervention. The milking group had a smaller placental residual blood volume (13.2±5.6 vs 19.2±5.4 ml kg(-1), P=0.01) and higher Hct levels at 36 to 48 h (57.5±6.6 vs 50.0±6.4 %, P=0.01). Five infants (42%) in the immediate group had a Hct of ≤47%, indicative of anemia. CONCLUSION: UCM results in placental transfusion in term infants at the time of elective cesarean section with higher Hct levels at 36 to 48 h of age.

Seven-month developmental outcomes of very low birth weight infants enrolled in a randomized controlled trial of delayed versus immediate cord clamping.

OBJECTIVE: The results from our previous trial revealed that infants with delayed cord clamping (DCC) had significantly lesser intraventricular hemorrhage (IVH) and late-onset sepsis (LOS) than infants with immediate cord clamping (ICC). A priori, we hypothesized that infants with DCC would have better motor function by 7 months corrected age. STUDY DESIGN: Infants between 24 and 31 weeks were randomized to ICC or DCC and follow-up evaluation was completed at 7 months corrected age. RESULT: We found no differences in the Bayley Scales of Infant Development (BSID) scores between the DCC and ICC groups. However, a regression model of effects of DCC on motor scores controlling for gestational age, IVH, bronchopulmonary dysplasia, sepsis and male gender suggested higher motor scores of male infants with DCC. CONCLUSION: DCC at birth seems to be protective of very low birth weight male infants against motor disability at 7 months corrected age.

Fostering evidence-based care in clinical teaching.

Understanding scientific research evidence and applying it to clinical practice is a focus in today's health care arena. Fostering evidence-based care (EBC) in clinical teaching is an effective way to help students learn to think critically, search for, evaluate, and incorporate the best research evidence into their clinical practice. For example, helping a student plan care for a woman creates a "teaching moment" for the application of scientific evidence to clinical practice. Essentially, EBC is a learned skill for both the student and the clinical teacher. It requires intellectual curiosity and a willingness to explore beyond "the way it has always been done." This article presents a review of the goals of clinical teaching, strategies to foster EBC, and tools to assess the readiness of the teacher, the student, and the clinical setting for EBC. By aligning the goals of clinical teaching with evidence-based strategies, both the educator and student strive together to provide midwifery care that is supported by available research.

The twilight envelope: a user-centered approach to describing roadway illumination at night.

Visual recognition functions, such as acuity and contrast sensitivity, deteriorate rapidly over the declining luminances found during civil twilight. Thus civil twilight, a critical part of the transition between daylight and darkness, represents lighting conditions that may be useful to describe artificial illumination. Automotive headlamps project a three-dimensional beam that ranges from illumination levels comparable to daylight at the vehicle to the dark limit of civil twilight (3.3 1x) at some distance ahead. This twilight envelope is characterized as a distance beyond which foveal visual functions are severely impaired, and thus it provides a general, functional description of the useful extent of the headlamp beam. This user-centered approach to describing illumination is useful for characterizing visibility when driving at night or in other artificially lit environments. This paper discusses the twilight envelope approach and its application to intervehicle variations in headlamp systems. Actual or potential applications of this research include user-centered description of artificial illumination and driver/pedestrian safety education.

Stair negotiation in older people: a review.

Locomotion on stairs is among the most challenging and hazardous activities of daily living for older individuals. This is evidenced by the reports that stair falls account for more than 10% of fatal fall accidents. The demands that stairs place on the musculoskeletal and cardiovascular systems are compounded by the need for input from the somatosensory, visual, and vestibular systems at various stages in the task. Many of these collaborating systems deteriorate with aging, thus increasing the difficulty and risk of failure in a task that inherently involves exposure to significant danger. The task itself varies in its degree of challenge depending on many structural and environmental factors that are outside the control of the stair user. This review explores existing literature in the area of stair negotiation by older persons in an effort to define the key factors associated with difficulty and safety on stairs and to interpret these findings in the light of possible interventions that could increase stair safety. Further research is needed to ensure that current recommendations for stair design are suitable for older stair users. A Glossary of Terms is also provided.

Predicting optimal accommodative performance from measures of the dark focus of accommodation.

Leibowitz and his colleagues found that accommodation rests at an intermediate distance that shows wide interindividual variation. They proposed that this intermediate dark focus is useful for correcting anomalous refractive errors, but this proposal was later questioned when different measurement techniques yielded discrepant dark focus values. The present study measured dark focus under two levels of visual attentiveness: (a) when performing an open-loop, active viewing task (aDF); and (b) when looking passively into darkness (pDF). These dark focus measures were then compared with an optimal accommodation distance that was derived from accommodative response functions in bright and dim luminance. The aDF measures were found to be more myopic (nearer) than the pDF measures and highly correlated with the optical accommodation distance. No significant relationship was found between pDF and optical accommodation distance. These findings confirm that measures of dark focus are affected by nonoptical aspects of the measurement technique; they also suggest that techniques that demand visual attention (aDF) yield dark focus values that are more useful for optimizing accommodation and potentially reducing fatigue in difficult situations.

The assured clear distance ahead rule: implications for nighttime traffic safety and the law.

The assured clear distance ahead (ACDA) rule holds the operator of a motor vehicle responsible to avoid collision with any obstacle that might appear in the vehicle's path. Although widely considered a fundamental responsibility of safe driving, the ACDA rule is routinely violated by most drivers under nighttime conditions. This fact does not necessarily imply reckless disregard for public safety, however. Rather the troublesome discrepancy between drivers' behavior and the principles of safe driving may be understood in terms of vehicle operators' lack of awareness of selective losses of visual function that occur in low light. This theoretical perspective holds basic implications both for traffic regulations and for assessment of liability in nighttime road accidents.

Dark focus values measured by retinoscopy: a clinical chart review.

The present study investigated the utility of dark retinoscopy as a technique to measure the dark focus of accommodation during routine clinical examinations. Using data from clinical examinations collected during a period of 6 months, a clinical chart review quantified dark focus and mean spherical equivalent refractive error for 480 patients ranging in age from 6 to 55 years. Results showed significant variations in mean dark focus values over the age groups. All groups showed wide interpatient differences, with mean dark focus values that were significantly nearer than the farpoint. Individual dark focus values ranged from 2.25 to -1.00 D (hyperopic), with an overall mean of 0.53 D. Potential clinical applications of dark focus-based correction are discussed.

How do the elderly negotiate stairs?

Stair navigation, particularly stair descent, is an extremely challenging and dangerous locomotor task, yet studies suggest that most elderly are unlikely to move to new residences in order to avoid this challenge. The knee and ankle are the key joints where adequate strength and power are required for safe stair descent, and it is not yet clear if sarcopenia in the elderly is likely to result in residual strength below that which is required for successful stair performance. Sensory cues are also critical, and the lack of literature on the specific roles of the various intrinsic and extrinsic factors that affect stair navigation is a clear indication of the need for such research in order to define safer strategies and optimal conditions for elderly individuals to transit between living areas of differing levels.

Differentiation of visibility and alcohol as contributors to twilight road fatalities.

Elevated road fatality rates at night involve multiple variables, each of which contributes to an unknown degree. In order to determine the relative contributions of reduced visibility and drivers' consumption of alcohol, we performed two quasi-experiments analyzing data recorded by the U.S. Fatal Accident Reporting System from 1980 through 1990. The results confirmed that both variables play a major role in nighttime road fatalities and revealed new evidence that they contribute differentially to two classes of fatal collisions: Degraded visibility in low illumination is associated primarily with collisions involving pedestrians and pedalcyclists, whereas drivers' consumption of alcohol plays a larger role in other fatal collisions.

Lateral phoria at distance: contributions of accommodation.

Lateral heterophoria at distance often is cited as an index of tonic vergence, yet recent research has shown that vergence in darkness is more convergent than most measures of phoria. Two experiments were conducted to investigate the possible role of accommodation in this discrepancy. Experiment I compared measures of distance phoria of 19 young adults with measures of vergence and accommodation of the same subjects. Dark vergence was found to be correlated with but significantly more convergent than distance phoria. Hierarchical regression analysis showed that individual measures of phoria were related to subjects' negative accommodation (from the dark focus to the distant target) as well as to dark vergence. Experiment II tested 13 young adults to evaluate three simple models of the influence of accommodation on distance phoria. Distance phoria was predicted best by a model that included the subjects' negative accommodation, accommodative vergence, and dark vergence. These findings support the hypothesis that distance phoria is influenced by accommodation for the fixation target. Dark vergence is a simpler index of tonic vergence.

Can normal outdoor activities be carried out during civil twilight?

Ambient illumination during civil twilight, which occurs approximately a half hour before sunrise and after sunset, has traditionally been characterized as posing no restriction on normal visual activities. However, consideration of the selective degradation of visual-recognition functions and the concurrent sparing of visual-guidance functions at the prevailing (relevant) luminance levels suggests that this characterization of civil twilight is no longer appropriate, particularly in light of the visual demands of industrialized society. Rather, special notice should be taken of the implications of selective degradation of visual recognition during civil twilight for traffic safety and other visually demanding hazardous tasks.

Vertical gaze direction and the resting posture of the eyes.

With horizontal gaze, the resting posture of binocular vergence typically corresponds to a distance of about 1 m. The effect of vertical direction of gaze on this basic resting posture was investigated. The dark vergence of twenty-four subjects was measured while they fixated a dim monocular light-point at vertical directions ranging from -45 degree (lowered) to +30 degrees (elevated). In one condition, gaze was varied by changes in eye position with the head held upright; in a second condition, gaze was varied by changes in head inclination with the eyes held in constant (horizontal) position with respect to the head. In both conditions, dark vergence shifted in the convergent (nearer) direction with lowered gaze and in the divergent (farther) direction with elevated gaze. The effect of varied eye inclination was larger, more variable across subjects, and more stable over time than that of varied head inclination. These findings indicate that multiple mechanisms contribute to gaze-related variations of the resting posture of the eyes. They may help to explain the variations of space perception and visual fatigue that are observed with different gaze inclinations.

Near work, visual fatigue, and variations of oculomotor tonus.

One hour of near work produced adaptive changes in the resting states of accommodation and binocular vergence, which may be responsible for different aspects of visual fatigue. Two groups of college students read from either hard copy or a video display terminal (VDT). Immediately before and after reading, the subjects' distance acuity, dark vergence, dark focus, and accommodative response accuracy for a monocular stimulus were measured. After reading, subjects also rated their subjective feelings of visual fatigue. Reading produced significant changes in both accommodation and vergence, which did not differ for the hard copy and VDT modes of presentation. Dark focus and accommodative responses shifted in the myopic direction by an average of 0.6 D and at least 0.35 D, respectively; dark vergence distance shifted in the convergent direction by an average of 11.4 cm. These changes were greatest for subjects whose initial resting postures corresponded to a far distance. After reading, one third of the subjects exhibited lower visual acuity at distance. This change was significantly correlated with changes in dark focus (r = 0.35) but not with changes in dark vergence (r = -0.12). In contrast, subjective ratings of visual fatigue were not correlated with changes in the dark focus (rho = 0.13), but they were significantly correlated with changes in dark vergence (rho = 0.58). These findings indicate that ordinary near work can produce significant changes in the resting states of accommodation and vergence, whose magnitude depend on the subject's initial oculomotor resting tonus.(ABSTRACT TRUNCATED AT 250 WORDS)

Total protection from hypoxic liver damage by fructose.

The purpose of these experiments was to evaluate the effect of carbohydrates on hypoxic cell death in the perfused rat liver. Lactate dehydrogenase (LDH) was released maximally at rates up to 300 U/g/h after 40 to 60 min of hypoxia in control livers from fasted rats or in livers perfused with glucose (20 mM). Fructose (20 mM) prevented the release of LDH completely. Rates of anaerobic glycolysis indexed by release of lactate were around 150 mumol/g/h in livers perfused with fructose but were undetectable in livers perfused with glucose. The results demonstrate that fructose prevents hypoxic damage in the liver presumably by providing glycolytic ATP in the absence of oxygen.

Does performance of tasks affect the resting focus of accommodation?

Measurements of the resting focus of accommodation were obtained with an infrared optometer while subjects engaged in four tasks: (1) passive viewing in darkness; (2) passive viewing of a laser speckle pattern; (3) active judgment of motion in a laser speckle pattern; and (4) mental arithmetic in darkness. The results showed resting focus measures to be comparable under all four conditions for some subjects. However, other subjects exhibited consistent increases or decreases in the resting focus position when asked to judge the direction of speckles within the laser test pattern or perform mental arithmetic. This finding suggests that "effort to see" may influence the resting focus of some subjects. Implications for measurement procedures and population estimates of the resting focus are discussed.