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PubMed1996

Tree-based, two-stage risk factor analysis for spontaneous abortion.

The authors utilize an analytic strategy that combines tree-based analyses with the method of Mantel-Haenszel to evaluate the association of 11 putative risk factors to spontaneous abortion by controlling for 19 potential confounders. Logistic regression is also used for comparison. The data for this study were collected in southern Connecticut, during 1988-1991. The putative risk factors are employment; standing, walking, or sitting more than 2 hours at work; exposure to vibration at work; commuting to work; reaching over the shoulders at work; carrying loads over 9 kg on the job; drinking alcohol or coffee in the first month of pregnancy; and gynecologic problems before pregnancy. The potential confounding factors are maternal age, marriage status, race, years of education mother's height, use of birth control, number of pregnancies, smoking before pregnancy, years of smoking, whether the mother stopped smoking, smoking marijuana, passive exposure to marijuana, chronic problems, infertility cocaine use and history of negative pregnancy outcomes. This analysis indicates that carrying loads over 9 kg on the job at least once a day increases the risk of spontaneous abortion by 70% (relative risk (RR) = 1.71, 95% CI 1.25-2.32). Drinking three or more cups of coffee daily in the first month of pregnancy also elevates the risk of spontaneous abortion (RR = 2.34, 95% CI 1.45-3.77). Reaching over the shoulders at least once daily has a marginally significant impact on spontaneous abortion (RR = 1.35, 95% CI 1.02-1.78). The authors conclude that this analytic strategy offers an efficient approach to the exploration of new risk factors for a disease where many potential confounders already exist.

Abortion, Spontaneous↗
PubMed1999

Long distance driving and self-induced sleep deprivation among automobile drivers.

OBJECTIVE: To evaluate the sleep hygiene and prevalence of sleep deprivation among a large sample of automobile drivers. DESIGN: From the 15th of June to the 4th of August 1996, with the help of the French highway patrol, we randomly stopped automobile drivers at the toll booths of Bordeaux and Biarritz. All subjects completed a validated questionnaire on sleep/wake habits during the year. After answering the questionnaire, subjects completed a graphic travel and sleep log of the three days preceding the interview. PARTICIPANTS: We randomly stopped 2196 automobile drivers. Ninety-one percent of the sample (mean age 43 +/- 13 years) agreed to participate in the survey. RESULTS: Fifty percent of the drivers decreased their total sleep time in the 24 hours before the interview compared with their regular self-reported sleep time. 12.5% presented a sleep debt > 180 minutes, and 2.7% presented a sleep debt > 300 minutes. Being young, commuting to work, driving long distances, starting the trip at night, being an "evening" person, being a long sleeper during the week, and sleeping in on the week-end were risk factors significantly associated with sleep debt. CONCLUSION: The results of the study highlight variables (long-distance driving, youth, sleep restriction) that are frequently associated with sleep-related accidents.

Accidents, Traffic↗
PubMed2006

How long and how much are nurses now working?

OBJECTIVE: Extended work schedules-those that vary from the standard eight hours per day, 35 to 40 hours per week-are common in nursing and contribute to problems with nursing recruitment and retention, in addition to compromising patient safety and the health and well-being of nurses. This study describes the nature and prevalence of such schedules across nursing settings. METHODS: Quantitative survey data collected as part of the Nurses Worklife and Health Study were analyzed. The sample consisted of 2,273 RNs. Demographic data, information about respondents' primary jobs (position, workplace, and specialty), and specific work schedule variables were analyzed, including data on off-shifts, breaks, overtime and on-call requirements, time off between shifts, and how often respondents worked more than 13 hours per day and on scheduled days off and vacation days. Respondents were also asked about activities outside of work, commuting time, and other non-nursing activities and chores. RESULTS: More than a quarter of the sample reported that they typically worked 12 or more hours per day, as did more than half of hospital staff nurses and more than a third of those with more than one job. A third of the total sample worked more than 40 hours per week, and more than a third worked six or more days in a row at least once in the preceding six months. Nearly a quarter rotated shifts. Almost one-quarter of nurses with more than one job worked 50 or more hours per week, and they were more likely to work many days consecutively, without sufficient rest between shifts, and during scheduled time off. Single parents were as likely as those with more than one job to work 13 to 15 hours per day, 50 to 60 hours or more per week, and many days consecutively. Seventeen percent of all nurses worked mandatory overtime, as did almost a quarter of the single parents. Nearly 40% of the total sample and more than 40% of hospital staff nurses had jobs with on-call requirements. CONCLUSIONS: The proportion of nurses who reported working schedules that exceed the recommendations of the Institute of Medicine should raise industry-wide concerns about fatigue and health risks to nurses as well as the safety of patients in their care.

Adult↗
PubMed1994

Physical exertion as a risk factor for spontaneous abortion.

This study examined the association of physical exertion and spontaneous abortion in a case-control study of 607 women whose pregnancies ended in spontaneous abortion and 1,287 women who delivered livebirths in Santa Clara County, CA, in 1986 and 1987. We interviewed women about the number of hours they spent doing heavy housework and caring for young children. We also interviewed women employed during their pregnancies (71% in each group) about their work schedule; the number of hours they worked, stood, commuted, and stooped or bent; and the number of times per day they lifted weights of > 15 pounds. Standing > 8 hours per day at work was the only variable associated with increased risk [adjusted odds ratio (OR) = 1.6; 95% confidence limits (CL) = 1.1, 2.3]. This association was present only for women with a history of spontaneous abortion (adjusted OR = 2.8; 95% CL = 1.4, 5.9). Among women with this history, the OR for a second trimester abortion was 4.9 (95% CL = 1.9, 12.2). Cleaning house for > 7 hours per week or caring for young children for > 50 hours per week was associated with decreased risk (adjusted OR = 0.6, 95% CL = 0.5, 0.9; adjusted OR = 0.8, 95% CL = 0.6, 1.0, respectively). Again, these associations were specific to women with a history of spontaneous abortion (adjusted OR = 0.4, 95% CL = 0.2, 0.7; adjusted OR = 0.5, 95% CL = 0.3, 0.8). These results indicate that the specific type of physical exertion, the amount of exertion, and the context of the exertion may be important.

Abortion, Spontaneous↗
PubMed2002

Distributed radiology clerkship for the core clinical year of medical school.

OBJECTIVE: The central role that diagnostic radiology has in the modern practice of medicine has not always been reflected in radiology's place in the curriculum. We developed a new radiology clerkship for undergraduate medical students during their core clinical year that was supported by Web technology. The assumptions underlying the design of the clerkship were that radiology is best learned from radiologists and that students are most receptive to learning radiology when it is related to concurrent patient care experiences. DESCRIPTION: Beginning in May 2000, a required radiology clerkship experience was incorporated into the core clinical year at Wake Forest University School of Medicine. The core clinical year was organized into three 16-week blocks of clerkships. Two or four independent half-day radiology tutorial sessions were included with each clerkship block, and attended by all students in the block (approximately 35 students), regardless of their specific clerkship assignments. There were ten different radiology tutorials, each given three times during the year as students rotated through the clerkship blocks. Thus, each student attended a radiology tutorial session every four to eight weeks during the year. The topics covered during the tutorials were correlated with the content of the clerkship blocks and included adult and pediatric chest radiology, adult and pediatric abdominal radiology, body CT, neuroradiology, obstetric ultrasound, gynecologic ultrasound, osteoporosis, adult and pediatric fractures, mammography, and cervical spine trauma. The tutorials included pre- and post-test, lectures, case presentations, and sometimes tours of the radiology department. The educational emphasis was on pragmatic case-based learning exercises, development of verbal and visual vocabulary, and learning when and where to seek more information. To provide continuity and organization, Web-based curriculum materials were designed and implemented as a component of the clerkship. The home page of the Web site provided the schedule, faculty names, attendance and grading policies, course overview, and links to individual tutorials. The pages for individual tutorials included educational objectives, glossary of radiology terminology relevant to the subject, lecture slides and handouts, and teaching cases. All students had laptop computers and access to the academic network, but did not use them during the actual tutorial sessions. DISCUSSION: Implementation of the radiology clerkship required extensive negotiation with directors of other clerkships so that students could be released from their other responsibilities in order to attend the radiology tutorials. The radiology clerkship format has proven to be complex in its administration, with faculty and students on different schedules commuting to the radiology lecture hall from various locations. Extensive use of e-mail and communication via the Web site have been instrumental in reminding faculty and students of upcoming sessions. Preliminary evaluations have indicated that students liked the radiology sessions and learned a great deal, but disliked the scheduling and the lack of continuity. An evaluation of the curriculum and its components is ongoing.

Clinical Clerkship↗
PubMed1977

Advances in electrical assist devices.

Marked improvements were realized in the development of electrically driven left ventricular assist systems. A volume reduction of 46%, a system weight reduction of 63%, and a factor of 2 improvement in overall efficiency (29%) were realized. The system, operating at a pressure of 120 mm Hg with a flow rate of approximately 7 L, requires only 7.5 W of input power. In addition, a unique brushless commutator was designed to replace standard brushes, thus increasing system life. A new polyurethane was synthesized for utilization in the TMS. This material has demonstrated high flex life in addition to being biocompatible. Further improvements in system weight and size, as well as efficiency, will be realized when flat plate pumps are mated to electric drivers.

Animals↗
PubMedDate not supplied

Electrohydraulic ventricular assist device development.

An electrohydraulic ventricular assist device has been developed. An axial flow pump driven by a brushless DC motor provides actuation. Energy is supplied by internal Ni/Cd batteries and by external Ag/Zn batteries, both rechargeable. Electromagnetic induction is used to pass energy through the skin with a transcutaneous energy transfer (TET) system. Physiologic control, battery management, motor commutation, and communication functions are performed by a surface mount internal controller. An infrared data link within the TET coils provides bidirectional communication between the external and internal controllers. A computer model was developed to predict system performance. The dimensions are 180 mm x 116 mm x 40 mm. An in vitro system pumped 5.7 L/min at 10 mmHg inflow and 100 mmHg outflow pressure. The internal battery can provide the projected energy requirements for 40 min after 540 charge/discharge cycles, and the external battery is capable of 4 hr of operation after 150 cycles. The TET system can deliver 60 W of power and exceeds 80% efficiency between 15 and 30 W. The device configuration is based on human cadaver and intraoperative fit trials. The device is being modified for calf implantation by redirecting the blood ports, increasing the output, and incorporating the internal controller in the unified device base.

Animals↗
PubMedDate not supplied

In vitro characterization of a magnetically suspended continuous flow ventricular assist device.

A magnetically suspended continuous flow ventricular assist device using magnetic bearings was developed aiming at an implantable ventricular assist device. The main advantage of this device includes no mechanical wear and minimal chance of blood trauma such, as thrombosis and hemolysis, because there is no mechanical contact between the stationary and rotating parts. The total system consists of two subsystems: the centrifugal pump and the magnetic bearing. The centrifugal pump is comprised of a 4 vane logarithmic spiral radial flow impeller and a brushless DC motor with slotless stator, driven by the back emf commutation scheme. Two radial and one thrust magnetic bearing that dynamically controls the position of the rotor in a radial and axial direction, respectively, contains magnetic coils, the rotor's position sensors, and feedback electronic control system. The magnetic bearing system was able to successfully suspend a 365.5g rotating part in space and sustain it for up to 5000 rpm of rotation. Average force-current square factor of the magnetic bearing was measured as 0.48 and 0.44 (kg-f/Amp2) for radial and thrust bearing, respectively. The integrated system demonstrated adequate performance in mock circulation tests by providing a 6 L/min flow rate against 100 mmHg differential pressure at 2300 rpm. Based on these in vitro performance test results, long-term clinical application of the magnetically suspended continuous flow ventricular assist device is very promising after system optimization with a hybrid system using both active (electromagnet) and passive (permanent magnets) magnet bearings.

Biomechanical Phenomena↗
PubMedDate not supplied

Development of a precise controller for an electrohydraulic total artificial heart. Improvement of the motor's dynamic response.

In an electrohydraulic total artificial heart developed at the National Cardiovascular Center (Osaka, Japan), two blood pumps are pushed alternatively by means of the bidirectional motion of a brushless DC motor for pump systole and diastole. Improvement in the dynamic response of the motor is very important to obtain better pump performance; this was accomplished by using power electronic simulation. For the motor to have the desired dynamic response, it must be commutated properly and the damping ratio (zeta), which represents transient characteristics of the motor, must lie between 0.4 and 0.8. Consequently, all satisfactory specifications with respect to power consumption must be obtained. Based on the simulated results, the design criteria were determined and the precise controller designed to reduce torque ripple and motor vibration, and determine motor stop time at every direction change. In in vitro tests, evaluation of the controller and dynamic response of the motor was justified in terms of zeta, power consumption, and motor stop time. The results indicated that the power consumption of the controller and the input power of the motor were decreased by 1.2 and 2.5 W at zeta = 0.6, respectively, compared to the previous system. An acceptable dynamic response of the motor, necessary for the reduction of torque ripple and motor vibration, was obtained between zeta = 0.5 and zeta = 0.7, with an increase in system efficiency from 10% to 12%. The motor stop time required for stable motor reoperation was determined to be over 10 msec, for a savings in power consumption of approximately 1.5 W. Therefore, the improved dynamic response of the motor can contribute to the stability and reliability of the pump.

Biomedical Engineering↗
PubMedDate not supplied

One piece ultracompact totally implantable electromechanical total artificial heart for permanent use.

An ultracompact, one piece, totally implantable electromechanical total artificial heart (TAH) has been developed as a permanent replacement for failing hearts. It consists of left and right pusher plate blood pumps (stroke volume 55 ml) made of titanium alloy (Ti-6Al-7Nb) sandwiching a miniaturized electromechanical actuator between them. The diameter of the TAH is 90 mm, with a thickness of 70 mm, yielding an overall volume of 400 ml. It weighs 450 g. Although it is miniaturized, it provided a maximum pump output of 8 L/min against a left afterload of 100 mm Hg. It required approximately 12 watts to provide a pump output of 6.5 L/min with maximum efficiency of 13.5%. To balance left and right flow, the right stroke length was made 10% shorter than the left, and an auxiliary compliance chamber was used to compensate for additional flow differences between them. Motor commutation pulses and a Hall effect pusher plate sensor signal were used in the controller to implement the left master alternate variable rate mode. The calf fitting study revealed excellent anatomic compatibility, and the first successful survivor was obtained in December 2001. Studies of system endurance and biocompatibility are required to ensure long-term reliability. This TAH is promising for permanent replacement of the failing heart as well as for bridge to heart transplantation for the smaller size group of end-stage cardiac patients.

Animals↗
PubMed1998

Measuring the ability to meet family needs in an intensive care unit.

OBJECTIVE: To measure the ability to meet family needs in an intensive care unit (ICU). DESIGN: Descriptive survey. SETTING: University hospital ICU. SUBJECTS: Ninety-nine next of kin respondents and 16 secondary family respondents were recruited. INTERVENTIONS: A modified Society of Critical Care Medicine Family Needs Assessment instrument was used. MEASUREMENTS AND MAIN RESULTS: Demographic variables included patient age, gender, diagnosis, Acute Physiology and Chronic Health Evaluation (APACHE) II score on admission, Therapeutic Intervention Scoring System (TISS) score on the date of interview, cumulative TISS of the ICU on the day of interview, number of patients in the ICU at time of interview, nurse/patient ratio for the patient, average nurse/patient ratio of the entire unit, day of the week of the interview, timing of the interview, number of ICU attending physicians who cared for this patient (scheduled for a period of seven consecutive days), number of nurses who cared for the patient, if a nurse was assigned the same patient on two consecutive days worked, length of stay in the ICU, and length of hospital stay. Demographic information concerning the family member included gender, age, commuting time to the hospital, visiting time in the hospital per day, number in family group, relationship to the patient, ethnic background, and education level. The additive score of all questions in the needs assessment instrument was calculated and used as the dependent variable. The independent variables were demographic information concerning patients, ICU, and respondents. The model coefficient of determination (R2adj) was 0.20 with a p = .0079. Greater family dissatisfaction (i.e., higher score) was present if there were more than two ICU attendings per patient (p = .048), or if the same nurse was not assigned on two consecutive days (p = .044). Family satisfaction increased if the respondent was female (p = .006), if the patient had a higher APACHE II score (p = .007), and if the patient's relationship with the most significant family member was brother/sister (p = .012). The family needs instrument was reliable and demonstrated a high degree of concordance with a second respondent in the same family surveyed. CONCLUSIONS: Communication by the same provider was important when measuring the ability of an ICU to meet family needs. Instrument scores and the ability to meet family needs differed depending on the gender and the relationship to the patient of the most significant family member. We speculate that this instrument may be a useful adjunct in assessing quality of critical care services provided.

APACHE↗
PubMed2002

Twenty-five-year trends in physical activity of 30- to 59-year-old populations in eastern Finland.

PURPOSE: The purpose of this study was to determine the 25-yr trends in leisure-time physical activity (LTPA), occupational activity (OPA), and commuting activity (CA) in the middle-aged population. METHODS: Six independent cross-sectional surveys were carried out at 5-yr intervals in the population living in eastern Finland (1972-1997). The common age range of the surveys was 30-59 yr, and the participation rates varied between 70 and 96%. LTPA, OPA, and CA were determined by a self-administered questionnaire. Based on their answers, the people were categorized into high, moderate, and low groups. RESULTS: The percentage of people who were completely sedentary during their leisure time decreased in both men and women. The estimated average 5-yr decrease was greater in women (-6%) than in men (-3%). Men showed only significant changes in high LTPA (+2.2%), whereas in women both moderate (+4.1%) and high (+1.8%) LTPA increased linearly. The percentage of people with low OPA linearly increased in both men (+3.5%) and women (+3.3%) The proportion of men with high OPA decreased in men (-3.2%) as well as in women (-2.6%). The increase in low CA in men (+5.9%) was twice as great as that in women (+2.6%). Men and women with high OPA increased their LTPA by the greatest extent. In both genders, the increase was almost twice as great as among groups classified as being less active during working hours. The prevalence of people who reported low in all three categories (OPA, LTPA, and CA) remained at the same level (6-8% in men, 7-9% in women). CONCLUSION: The proportion of the Eastern Finnish populations classified as sedentary or having only moderate physical activity during their leisure time is still very high among both men (75%) and women (82%), even though the percentage of highly active people increased between 1972 and 1997.

Adult↗
PubMedDate not supplied

A comparison of learner outcomes to traditional and videotaped classes.

A course was taught to registered nurse students using videotaped classes shown on a bus while students commuted to and from a distant clinical site. Course outcomes for this group were compared with course outcomes for a traditional classroom-taught group of registered nurse students. Outcomes were quite similar, thus making this method of technology use and time management an appropriate teaching outreach/recruitment technique for the college to use with the registered nurse student population.

Adult↗
PubMed1986

Effects of centre-of-rotation shift on contrast and spatial resolution of the SPECT system.

The effects of centre-of-rotation (COR) shift of the rotating camera-based single photon emission commuted tomography (SPECT) system on tomographic images were investigated quantitatively. Contrast and spatial resolution variations as a function of COR shift were measured for all shifts less than 1 pixel, in steps of 0.1 pixels. This region encompasses the typical COR variations. The behaviour of these indices was analysed. In addition, the validity of the limit imposed on the allowable COR shift, as utilized in the current SPECT quality control protocols, was examined. The value of either +/- 0.5 or +/- 0.25 pixels is presently in use as the limit. From this study, both limits result in the loss of resolution. The resolution loss will increase the uncertainties of volume and concentration measurements. For a COR shift of 0.25 pixels, the spatial resolution loss is approximately 5%. This small spatial resolution loss may not affect the qualitative evaluation of tomographic images. However, any loss of resolution should be avoided. For a COR shift of 0.1 pixels, there is no observed loss of resolution. This value should be a desirable choice as the maximum allowable COR shift since it ensures the optimum performance of the SPECT system.

Rotation↗
PubMedDate not supplied

Exposure to New York City as a risk factor for heart attack mortality.

OBJECTIVE: If New York City (NYC) residents' unusually high rate of ischemic heart disease (IHD) results from chronic exposure to that city, there might also be an effect of acute exposure among visitors to NYC. We explored this possibility and also whether IHD is reduced among NYC residents dying away from the city. METHODS: Using all US death certificates for 1985-1994, we examined (correcting for age, race, and sex) IHD deaths in three groups: NYC residents who died in the city, non-NYC residents visiting the city, and NYC residents traveling out of the city. RESULTS: IHD deaths among NYC residents dying in the city were 155% of the expected proportion (p < .0001). Among visitors to the city, such deaths were 134% of the expected proportion (p < .0001). The proportion of IHD deaths among NYC residents dying out of the city was only 80% of the expected value (p <.0001). These effects are not due to nearby commuters, recent immigrants, local classification practices, or socioeconomic status, and they do not appear in other US cities. CONCLUSIONS: With both chronic and acute effects of exposure to NYC, these data are consistent with the hypothesis that the stress of NYC is linked to the high rate of IHD.

Environmental Exposure↗
PubMedDate not supplied

Incorporating pedagogical principles in developing an online nursing research course.

Since 1998, developing online courses to accommodate nontraditional students has been a major focus at a public commuter university in the southeast. Concern about the quality of online instruction prompted a number of faculty members in different disciplines to explore pedagogically sound methods for improving and evaluating their teaching using instructional technology. In response to the impetus to have a framework for the development of online courses, a seminar series based on the Seven Principles of Undergraduate Education was developed. On the basis of the pedagogical principles presented during the seminar series, the online nursing research course was redesigned to be more learner-centered by increasing student-to-student and student-to-faculty interaction. Seven interactive modules were developed to address students' diverse learning styles. Using this approach for teaching an online nursing research course, students were able to learn the important concepts typically taught in a traditional, face-to-face course, while managing family and work responsibilities.

Attitude of Health Personnel↗
PubMed1998

The effect of heavy maternal workload on fetal growth retardation and preterm delivery. A study among southern Thai women.

Heavy maternal workloads are considered to be hazardous to the fetus. The effects of physical activity during pregnancy on low birth weight (LBW), small for gestational age (SGA), and prematurity were assessed from a sample of 1797 women in a follow-up study at the antenatal clinic of two hospitals in southern Thailand. The women were interviewed twice, at 17 and 32 gestational weeks. Outcome data were obtained from medical records and the newborn gestational age determined using Dubowitz's score. The risk of SGA was elevated for women working > 50 hours/week, squatting in work, commuting > 1 hour/day, and having high psychological job demands; the risk of preterm delivery was increased with obstetrical complications. Women who worked long hours and had demanding work conditions had an elevated risk of giving birth to SGA infants but not of preterm delivery.

Adult↗
PubMed1999

The effect of male occupational exposure in infertile couples in Norway.

The objective of the study was to assess whether reduced semen quality in infertile couples is associated with occupational exposures known to be hazardous to fertility. Results of the first semen analysis were linked to occupational exposure data from a self-administered questionnaire. Reduced semen quality was found in men exposed to electromagnetic fields (odds ratio, 3.22; confidence interval, 1.46 to 7.09). A tendency toward reduced semen quality was seen in commuters (OR, 1.52; CI, 0.89 to 2.59), shift workers (OR, 1.46; CI, 0.89 to 2.40), and men exposed to heavy metals (OR, 1.47; CI, 0.76 to 2.87). In general, the impact of occupational exposure on semen quality in infertile couples in Norway seemed to be minor. However, occupational exposure mapping is still important in individual infertility investigations.

Adult↗