Evaluation of an institution-based protocol for postpartum rubella vaccination.
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Clinical Protocols↗
Biomedical subjects
L Oppenheimer
Publications and source records attributed to L Oppenheimer.
Diagnosis of low-lying placenta: can migration in the third trimester predict outcome?
OBJECTIVES: To investigate the relationship between the rate of migration of a low-lying placenta during the third trimester and the eventual route of delivery. METHODS: All patients with a placenta lying within 3 cm of the internal cervical os or overlapping it on transvaginal ultrasound at > or = 26 weeks' gestation were included in the study. The exact distance between the center of the internal cervical os and the leading edge of the placenta was measured by transvaginal sonography, repeated at approximately 4-week intervals until delivery. RESULTS: The mean rates of migration in patients who had (n = 7) and who did not have (n = 29) Cesarean section for placenta previa were +0.3 mm/week and +5.4 mm/week, respectively (P < 0.0001). When the placental edge was initially > 20 mm from the internal os, migration occurred in all cases and no Cesarean section for placenta previa was performed. For those between -20 mm and +20 mm, sufficient migration to avoid Cesarean section occurred in 88.5% of cases. Beyond a 20 mm overlap, significant placental migration did not occur and all patients required Cesarean section. CONCLUSION: Placental migration may occur progressively throughout the third trimester. The initial position of the placental edge and the subsequent rate of migration can be used to predict the eventual route of delivery.
Adult↗
Influence of an educational program on medical students' attitudes to substance use disorders in pregnancy.
Substance use disorders (SUDs) in pregnancy are becoming increasingly prevalent. Our study aimed to measure the effect of a teaching module on alcohol, tobacco, and drug use on the attitude of second year medical students toward pregnant women with SUDs. A questionnaire was administered to 84 medical students before a 5-week systems block on human reproduction, which included specific learning events related to SUDs. The questionnaire was readministered at the completion of the block. Pre- and postintervention scores were compared. Students showed significant improvement (p < .05, reliability coefficient 0.90) in their level of comfort in dealing with womenwith SUD in pregnancy. Other positive trends relating to attitudes toward drug- and alcohol-dependent women during pregnancy were also identified. SUD teaching interventions among medical students can improve their comfort level and attitude toward pregnant women with SUDs. This supports the current initiative of Project CREATE (Curriculum Renewal and Evaluation of Addiction Training and Education) to implement a comprehensive undergraduate SUD teaching program in Canadian medical schools.
Attitude of Health Personnel↗
Recent trends in fetal and infant outcomes following post-term pregnancies.
All births and infant deaths in 1985 87 and 1992 94 in Canada, except in Ontario and Newfoundland, were analyzed to assess the potential impact of the recent increased use of elective labour induction for post-term pregnancies. Probabilistic linkage was carried out of infant death records (Canadian Mortality Database) and respective birth registrations (Canadian Birth Database) for the periods 1985 87 and 1992 94. The combined fetal and infant mortality declined by 20 30% between 1985 87 and 1992 94 at each gestational week beginning at 37 weeks, with no increased reduction among post-term pregnancies. Asphyxia-related fetal and infant deaths, the most likely cause of death being preventable by labour induction for post-term pregnancies, did not decrease among post-term pregnancies. In contrary, a substantial decrease of asphyxia-related deaths was observed at 37 and 38 weeks over the same periods of time. Because fetal and infant deaths are rare events and because the number of pregnancies passing 42 weeks of gestation decreased dramatically during 1992 94, statistically unstable results may be inevitable in the comparison of mortality in this group of pregnancies.
Canada↗
The impact of measurement error on the comparison of two treatments using a responder analysis.
Investigators often report results of studies comparing the proportions of subjects who have clinically meaningful responses to various therapeutic regimens. When the outcome variable is a continuous measure this involves dichotomizing the observed response based on a predefined threshold value. The effect of this strategy is examined, paying particular attention to the impact of measurement error on the resulting estimates of treatment effect (difference in the proportion responding). Expressions are obtained for quantifying the magnitude and direction of the resulting bias, and these are illustrated in a study evaluating a pharmaceutical treatment for osteoporosis.
Administration, Oral↗
Prevention of nonvertebral fractures by alendronate. A meta-analysis. Alendronate Osteoporosis Treatment Study Groups.
OBJECTIVE: To evaluate the effect of treatment with alendronate sodium, a potent aminobisphosphonate, on the incidence of nonvertebral fractures in postmenopausal women with osteoporosis. DATA SOURCES: Published data and data on file at Merck Research Laboratories. STUDY SELECTION: All completed prospective, randomized, placebo-controlled alendronate trials of at least 2 years' duration (5 studies). DATA EXTRACTION: All subjects were women with osteoporosis between the ages of 42 and 85 years, postmenopausal at least 4 years, with lumbar spine bone mineral density (measured using dual-energy x-ray absorptiometry) at least 2.0 SD below the mean for young adult women. All women randomized to treatment with placebo or alendronate at a dose higher than 1 mg per day for at least 2 years were included. DATA SYNTHESIS: In the placebo group (n=590), 60 women reported nonvertebral fractures during 1347 patient-years at risk (overall rate, 4.45 women with fractures per 100 patient-years at risk). In the alendronate group (n = 1012), 73 women reported nonvertebral fractures during 2240 patient-years-at risk (overall rate, 3.26 women with fractures per 100 patient-years at risk). The estimated cumulative incidence of nonvertebral fractures after 3 years was 12.6% in the placebo group and 9.0% in alendronate group. The relative risk for nonvertebral fracture estimated using the Cox proportional hazards model was 0.71 (95% confidence interval,0.502-0.997) (P=.048). A reduction in risk was consistent across each of the studies and at each major site of osteoporotic fracture, including the hip and wrist. CONCLUSION: In postmenopausal women with osteoporosis, treatment with alendronate reduces the risk of nonvertebral fractures over at least 3 years.
Adult↗
Response of ventilator-dependent patients to different levels of proportional assist.
Proportional-assist ventilation (PAV) is a form of ventilatory support in which airway pressure increases in proportion to patient effort. Because it effectively reduces the mechanical load to an adjustable extent, PAV permits the study of the pattern of breathing in patients with respiratory disease when unconstrained by abnormal respiratory mechanics. We studied 11 patients with assorted medical problems requiring ventilatory support. The patients were switched to PAV, and the level of support was varied from near-maximal levels to the lowest tolerable level. Each level was maintained for several minutes while ventilation (VE), tidal volume (VT), and respiratory rate (f) were monitored. The breathing pattern observed with the highest assist varied substantially among patients. The ranges (and means) of VE, VT, and f were 5.6-18.7 (12.8) l/min, 203-844 (517) ml, and 18-33 (25) breaths/min, respectively. The correlation between VT and VE at the highest assist was very high (r = 0.91), suggesting that ventilatory demand is the most important determinant of VT variability. There were no systematic changes in breathing pattern as the level of assist was altered; at the highest and lowest levels of support, VE, VT, and f were, respectively, 12.8 +/- 5.4 (SD) vs. 11.6 +/- 4.3 l/min, 517 +/- 217 vs. 459 +/- 175 ml, and 25.0 +/- 4.2 vs. 25.7 +/- 3.9 breaths/min. These results indicate that within each patient, in a given state, there exist unique values for a desired VE, VT, and f that are largely independent of the mechanical load; if assist is increased, patient effort is decreased to maintain the desired ventilatory targets.
Adult↗
The excitation-adaptation model of pediatric chronic illness.
This article examines the value of the psychosomatic family model for the study of chronically ill children. Four conceptual problems arise in the discussion of this model: the unidirectional causality of the model; the function of the sick child for the family system; the pathology of the family characteristics; and the disease type. In the present study, we propose (a) that a distinction be made between uncontrolled and controlled forms of disease, and (b) that the family characteristics of "cohesion" and "adaptation" be examined in relation to the parental capacity for problem solving and the acceptance or rejection of the child by the parents. This is shown by means of empirical research. In this empirical study, 20 families with a child suffering from controlled asthma are compared with 20 families with a child suffering from uncontrolled asthma. Contrary to the assumptions derived from the psychosomatic family model, the results show significantly more cohesion and structure in the group with a child suffering from controlled asthma. The findings from this study are integrated in a new model for the study of chronic childhood illness--"the excitation-adaptation model." In this model, two circular processes are emphasized involving (a) the progress of the illness and the way in which parents and child deal with medication and medical advice (therapy compliance), and (b) the factors influencing the therapy compliance on the part of the parents, the family, and the child. By studying these factors in connection with the management of the illness, it should become clear whether family characteristics are adaptive or pathological.
Adaptation, Psychological↗
Intractable or uncontrolled asthma: psychosocial factors.
The purpose of this study was to address the question of why, when there is a comparable severity of asthma, medical facilities, and treatments, some children develop controlled asthma whereas other children do not and are frequently ill. The major research questions pertained to whether families with a child with uncontrolled asthma differ from families with a child with controlled asthma as regards family characteristics and child-rearing attitudes, whether particular psychosocial variables relate to the severity of the asthma, and whether the interaction between the severity of the asthma and its controllability may clarify the role of psychosocial variables. Two studies were conducted, in which 70 asthmatic children (age range 9-15 years) and their families participated. The children and their caregivers were presented with measures assessing parental child-rearing attitudes, the problem-solving abilities of the caregivers, family functioning, and emotional disorders in the asthmatic children. Contrary to the assumptions derived from the psychosomatic family model, the findings of these studies suggest, among other things, that cohesion of family members and rigid manner of function of caregivers may have a positive rather than a negative influence on the welfare of the asthmatic child. In addition, controlled asthma was found to relate to the correct use of medication, which was predominantly evident in more structured and interdependent family environments. Of major importance is the conclusion that a distinction between controlled and uncontrolled asthma leads to a better insight into the role of psychosomatic variables than a distinction on the basis of the severity of the asthma.
Asthma↗
The early prenatal diagnosis of bilateral renal agenesis using transvaginal sonography and color Doppler ultrasonography.
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Adult↗
Eliminating needless testing in intensive care--an information-based team management approach.
OBJECTIVE: To determine if the application of an information-based management system in adult intensive care units (ICU) can produce sustained decreases in the use of laboratory resources and costs. DESIGN: Interventional study with prospective data collection on consecutive patients admitted during three time periods. SETTING: A 10-bed adult surgical ICU and an eight-bed adult medical ICU in a tertiary care hospital. PATIENTS: All patients admitted to an ICU during a 7-month baseline period (n = 647), a 1-yr intervention period (n = 1236), and a 2-yr follow-up period (n = 2349). INTERVENTIONS: Using a management database to track the use of 123 laboratory investigations during the baseline period, nine frequently ordered investigations (determination of blood gases, glucose, potassium, electrocardiogram, chest radiograph, sodium, chloride, complete blood count with differential, and serum osmolality) were targeted for reduction. Specific policies were developed by a multidisciplinary committee within the ICU to reduce the utilization of these laboratory, radiology, and cardiology tests. The policies were applied to all patients admitted during the 1-yr intervention period and during the 2-yr follow-up period. MEASUREMENTS AND MAIN RESULTS: A 25% reduction was observed in the frequency of all 123 monitored tests during the intervention period. The most dramatic reductions occurred in the nine targeted tests (range 19% to 46%) (p < .001). There were significant reductions in only 13 of the untargeted 114 investigations during this period. Potential annual cost savings were > $150,000 Canadian. No increases in ICU mortality rate, length of stay, or cost of medication were observed, and the reductions in the frequency of targeted tests were maintained during the 2-yr follow-up period. CONCLUSIONS: Application of an information-based multidisciplinary management system in the ICU can produce marked and sustained reductions in unnecessary testing in a cost-effective manner. Although rationing of intensive care services may be necessary, reducing needless testing can be a safe and effective cost-containment strategy in the ICU.
Cost Control↗
Near-infrared spectrophotometric device to measure fluid exchange in blood-perfused organs.
We describe an on-line spectrophotometric device designed to estimate the volume of transvascular fluid exchange (VE) continuously in isolated organ preparations. The device is interposed in the perfusion circuit, and VE is continuously estimated from changes in light transmission proportional to changes in perfusate hematocrit. In our perfusing circuit, hemolysis was negligible. Using hourly determinations of free hemoglobin, we estimated errors in VE due to hemolysis to be on the order of 1 ml for every hour of perfusion (expt I). When logarithms of on-line spectrophotometric signals were plotted against measured hematocrits (expt II), there was always an excellent linear correlation over a wide range of hematocrits (from 0.247 to 0.583). Finally, there was also an excellent correlation between spectrophotometric [QF(Spectr)] and gravimetric [QF(wt)] estimates of constant rates of transvascular fluid exchange in five isolated excised canine left lower pulmonary lobes, where QF(Spectr) = delta VE/delta t and QF(wt) = delta wt/delta t (expt III). QF(Spectr) = 1.035QF(wt) - 0.038 (r2 = 0.9772).
Animals↗
Proportional assist ventilation. Results of an initial clinical trial.
The response to proportional assist ventilation (PAV) was tested in four normal subjects during heavy exercise and in five ventilator-dependent patients recovering from assorted medical disorders. The apparatus consisted of a rolling-seal piston coupled to a motor that generated pressure in proportion to inspired flow and inspired volume, with the gains adjusted such that the proportionality between airway pressure (Paw) and instantaneous patient-generated pressure (Pmus) was approximately 1:1 (i.e., machine-amplified patient effort by a factor of 2). Normal subjects responded to PAV by decreasing their own effort, as judged from esophageal pressure, such that the changes in ventilation and breathing pattern were rather small (VE: 64.8 +/- 3.6 during PAV versus 56.0 +/- 4.3, p less than 0.01; VT: 2.39 +/- 0.24 versus 2.02 +/- 0.17, p less than 0.05; f: 27.5 +/- 1.9 versus 28.0 +/- 2.2, NS). In patients, elastance ranged from 20 to 35 cm H2O cm/L, resistance ranged from 5 to 10 cm H2O/L/s, and maximal inspiratory pressure ranged from -16 to -65 cm H2O. After a period of observation during synchronized intermittent mechanical ventilation (SIMV) the patient was switched to PAV and maintained on it for 1 to 3 h. No patient had to be replaced on SIMV because of discomfort or deterioration in any of the monitored variables. During PAV peak airway pressure was less than half the value observed with the IMV breaths (16.6 +/- 2.4 versus 35.4 +/- 3.4 cm H2O, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Pulmonary oedema in isolated lung lobe after inhalation injury.
Pulmonary oedema was produced in isolated lung lobes with steam and provided direct continuous measurements of transudation as it occurred. Transvascular flux (Qf) and weight gain (Gw) of the lobe increased immediately and the transudation reached its peak within half an hour after inhalation injury. Studies of protein content, colloid osmotic pressure of bronchial exudate and water content of lung, reconfirmed the increase in pulmonary capillary permeability. Marked haemoconcentration was revealed. Plasma leaked 113 g (25 per cent), plasma protein leaked 1.96 g (9.7 per cent) during the experiment. Based on the measured arterial pressure (Pa), vein pressure (Pv), arterial occlusion (Pao), venous occlusion (Pvo), double occlusion (Pdo) and blood flow through the lobe (Qt), the total vascular (Rt), arterial (Ra), middle compartment (Rmid) and venous (Rv) resistances were calculated. All the resistances were increased and the Qt showed a decrease after inhalation injury.
Animals↗
How is maximal expiratory flow reduced in canine postpneumonectomy lung growth?
Six dogs underwent left pneumonectomy (P) at 10 wk of age, while four littermates had a sham operation (C). All dogs were studied at 26 wk of age. Pressure capsules were placed on the right lung to measure lobar alveolar pressures and flows, and a Pitot-static tube was used to measure dynamic intrabronchial pressures. Vital capacity and lung elastic recoil did not differ between P and C. At all lung volumes studied, maximum expiratory flows (Vmax) in P were substantially lower than in C. Choke points in P were located more peripherally than in C. In central airways subjected to the same distending pressure, calculated cross-sectional area was significantly lower in P than in C, indicating different bronchial area-pressure behavior. In P, frictional resistances of the right lower, middle, and cardiac lobes were significantly higher than those in C. These results indicate that the reduction in Vmax in P was greater than would have been expected on the basis of reductions in central airway diameter alone. We calculated that, in the middle vital capacity range, approximately 60% of the decrease in Vmax was due to changes in dynamic central airways properties, and approximately 40% was due to increased lobar frictional resistance related to compensatory growth.
Airway Resistance↗
Vascular properties of canine lungs perfused with Eurocollins solution and prostacyclin.
Although Eurocollins solution (ECS) is commonly used for lung preservation, its vascular effects and their time course and response to pharmacological interventions are not well understood. The effect of 4 degrees C ECS on the pulmonary circulation was assessed in excised canine left lower lobes. The roles of static oxygen inflation and prostacyclin infusion during ECS perfusion were also examined. The lobes were divided into five groups: time control (A), ECS with oxygen (B), ECS without oxygen (C), ECS with glycine buffer (D), and ECS with prostacyclin (E); group D was the control for E. Eurocollins solution had no effect on gas exchange but had a marked effect on the pulmonary circulation. Vascular conductance decreased from 22.6 to 18.9 mL/min/cm H2O and from 21.3 to 14.1 mL/min/cm H2O with average vascular closure increasing by 1.2 and 2.1 cm H2O in groups B and C, respectively. The decreased vascular conductance and increased vascular closure was associated with a reduction in vascular compliance from 1.63 to 1.25 mL/cm H2O. When prostacyclin was added to ECS, the reduction in vascular closure was much less and was associated with a decrease in vascular closure and no loss of vascular compliance. Eurocollins solution increases pressure cost for perfusion by causing both vascular obstruction and increased tone, especially when oxygen is not provided. This is significantly overcome by addition of prostacyclin infusion during ECS perfusion.
Animals↗
Slow phase of transvascular fluid flux reviewed.
In six circuit experiments using a clinical hemofiltration device, we validated a colorimetric technique to measure transvascular volume exchange (VE). In 12 isolated excised canine left lower lobes, continuous colorimetric measurements of VE correlated well with calculations of VE from changes in microhematocrit obtained simultaneously. We introduced step increases in microvascular hydrostatic pressure (Pc) of 9 +/- 4.8 (SD) cmH2O and followed the time course of weight and continuous hematocrit changes measured colorimetrically for 40 min, after which Pc was returned to base line, while measurements were continuously obtained. This procedure was repeated for an additional 30 min. VE was calculated from the hematocrit signals and compared with the time course of the weight signal. After increases in Pc, followed by a rapid weight gain, weight signals followed a slow exponential time course, whereas the calculated VE changed linearly. VE reflected approximately 60% of the slow weight gain. When Pc was decreased, weight signals decreased exponentially, whereas VE continued to increase linearly at a slower rate. These results suggest that a significant component of the slow weight signal represents slow vascular volume changes. Contrary to what the weight signal suggested, edema was never reabsorbed over the range of Pc measured.
Animals↗
Measurement of extravascular lung water during abdominal aortic surgery.
Cross-clamping of the abdominal aorta can be associated with significant changes in haemodynamic variables. However, intraoperative changes in extravascular lung water (EVLW) have not been studied. Nine patients undergoing elective surgery, either aortic aneurysm repair or aorto-bifemoral grafting, were monitored invasively with arterial lines, pulmonary artery catheters and Edwards lung water catheters inserted in either the brachial or axillary artery. Determinations of EVLW were made prior to and five minutes after application of the aortic cross-clamp and at 30-minute intervals during the course of the operation. Baseline EVLW was found to be 7-9 ml.kg-1. There were no significant changes in haemodynamic variables and no changes in EVLW with cross-clamping of the aorta. The EVLW did not change during the course of surgery. The EVLW did not increase in the absence of sustained elevation of pulmonary capillary wedge pressure. One patient developed an axillary artery thrombosis which required thrombectomy at the site of lung water catheter insertion. Two other patients lost their distal pulses without overt ischaemic changes. It was felt that such relatively high incidence of complications precluded further use of the lung water catheter in the axillary or brachial artery.
Adult↗