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Biomedical subjects

R Brant

Publications and source records attributed to R Brant.

At least 37 records · Page 2Linked to original sources
PubMed1998

Cuing effect of "all of the above" on the reliability and validity of multiple-choice test items.

It is generally acknowledged that alternatives such as none of the above and all of the above should be used sparingly in multiple-choice (MC) items. But the effect that all of the above has on the reliability and validity of an MC item is unclear. This study compared the results of a single-response (SRa) item format that included all of the above as the correct response to a multiple-response (MR) item format that required examinees to select all of the available alternatives for a correct response. A crossover design was used to compare the effect of formats on student performance while item content, scoring method, and student ability levels remained constant. Results indicated that the SRa format greatly distorted examinee performance by elevating their scores because examinees who recognized two or more alternatives as being correct were cued to select all of the above. In addition, the SRa format significantly reduced the reliability and concurrent validity of examinee scores. In summary, the MR format was found to be superior. Based upon new empirical evidence, this study recommends that whenever an educator wishes to evaluate student understanding of an issue that has multiple facts, the SRa format should be avoided and the MR format should be used instead.

Alberta↗
PubMed1998

Different effects of heparin in males and females.

OBJECTIVE: To determine whether women have a Pharmacological predisposition to bleeding and a worse outcome than men during heparin therapy, in light of recent studies showing that women have a higher risk of bleeding complications following anticoagulant therapy for thrombotic disorders than men. DESIGN: Prospectively planned subgroup analysis of a double-blind randomized study. SETTING: Academic tertiary care hospitals in Hamilton, Ont. PATIENTS: A total of 199 consecutive patients (105 women, 93 men) presenting with proximal deep vein thrombosis. (One patient was not included due to incomplete data). OUTCOME MEASURES: Activated partial thromboplastin time (APTT) values and heparin levels were assessed every 4 to 6 hours after a standard heparin bolus and infusion. The effect of sex on heparin doses and levels was also assessed after stable therapeutic heparin infusions were achieved. RESULTS: The women had higher heparin levels than the men (0.560 [standard error of the mean, SEM 0.056] units/mL v. 0.347 [SEM 0.062] units/mL, p < 0.0001) and higher APTT values (94.9 [SEM 0.50] seconds v. 81.2 [SEM 0.53] seconds, p = 0.0002) 4 to 6 hours after being given the same heparin bolus and infusion doses. After achieving therapeutic APTT values, the women received lower heparin doses than the men (27.9 [SEM 0.24] 1000 units/24 hours v. 34.5 [SEM 0.24] 1000 units/24 hours, p < 0.0001) but had higher heparin levels (0.349 [SEM 0.035] units/mL v. 0.292 [SEM 0.036] units/mL, p = 0.034). The effect of sex was also determined after correcting for the known effects of weight and age on heparin therapy. After adjusting for patient weight, among the women, older women had higher heparin levels but, among the men, there was little effect of age. There were no sex differences with respect to bleeding complications or recurrent thromboembolic disease. CONCLUSION: Women showed alterations in the pharmacokinetics of heparin, which could explain a predisposition to bleeding complications. Under the heparin protocol used in this study, heparin doses were rapidly adjusted, which may explain why rates of bleeding complications and recurrent thromboembolism were similar in men and women. We do not recommend changes in heparin therapy based on these results, but suggest the use of protocols that assess coagulation parameters frequently and then adjust heparin doses rapidly, in order to individualize therapy. Further study is required to determine whether there are sex differences in bleeding complications associated with anticoagulant therapy, and to confirm the altered pharmacokinetics of heparin in women.

Aging↗
PubMed1997

Declining sex ratios in Canada.

OBJECTIVE: To examine the trends in the proportion of annual live births that were male in Canada and to compare the trends with those in the United States. DESIGN: Analysis of census data. SETTING: Canada as a whole and 4 main regions (West, Ontario, Quebec and Atlantic). SUBJECTS: All live births from 1930 to 1990. OUTCOME MEASURES: Sex ratio (expressed as the proportion of total live births that were male [male proportion]) overall and by region. RESULTS: The male proportion in Canada decreased significantly after 1970 (p < 0.001); this represented a cumulative loss of 2.2 male births per 1000 live births from 1970 to 1990. Although a decrease was observed in all four regions studied, only that in the Atlantic region was significant (p < 0.001), representing a cumulative loss of 5.6 male births per 1000 live births from 1970 to 1990. A significant decrease in the male proportion was also observed in the United States from 1970 to 1990 (p < 0.001), although to a lesser degree than that observed in Canada, and represented a cumulative loss of 1.0 male births per 1000 live births. CONCLUSIONS: The decreased sex ratio in Canada adds to the growing debate over changes in biological markers and their potential causes. In addition, the study illustrates the potential use of the sex ratio as a widely available, unambiguous measure of the reproductive health of large populations.

Birth Rate↗
PubMed1997

Sorbitol 2.5% mannitol 0.54% irrigation solution for hysteroscopic endometrial ablation surgery.

PURPOSE: To determine if systemic absorption of sorbitol 2.5%/mannitol 0.54% irrigation solution (165 mosm.L-1) during hysteroscopic endometrial ablation with diathermy is associated with hyponatraemia and hypoosmolality. METHODS: In 35 day surgery patients in a university hospital we measured baseline preoperative variables: serum sodium and creatinine concentrations and osmolality, haematocrit, haemoglobin, urine osmolality and sodium concentration, and weight. Fractional excretion of sodium (FENa) was calculated. The same observations were obtained postoperatively before discharge (one hour post resection). Volumes of intraoperative fluid irrigation intravasation and perioperative intravenous fluid absorption (lactated Ringer's solution) were estimated clinically (volumetric). RESULTS: The mean (+/-SD) serum sodium concentration preoperatively was 140.3 +/- 2.4 mmol.L-1; and postoperatively, 139.7 +/- 2.2 mmol.L-1 (P = NS). The serum osmolality decreased from 285.4 +/- 4.5 to 282.6 +/- 4.1 mmol.kg-1 (P < 0.001). The mean volume of intravasated irrigation fluid was 26.4 ml (range 0-300). During the same time, the FENa increased from 0.57% to 0.79% (P < 0.001). CONCLUSION: In these patients, closely and continuously observed for imbalance between infused and collected irrigation fluid, these was no clinical evidence for hyponatraemic hypoosmolality. However, there was a small 1% +/- 1.5% (mean +/- SD; range -3.4 to 3.6%) decrease in plasma osmolality despite adequate blood volumes as shown by urinary sodium indices.

Adult↗
PubMed1997

Interaction of cross-sectional area, driving pressure, and airflow of passive velopharynx.

Previous studies have shown that, when the pharyngeal muscles are relaxed, the velopharynx is a highly compliant segment of the pharynx. Thus, under these circumstances, cross-sectional area of the velopharynx (AVP), driving pressure across the velopharynx (DeltaP), and inspiratory airflow (VI) will be mutually interdependent variables. The purpose of the present investigation was to describe the interrelation among these three variables during inspiration. We studied 15 sleeping patients with obstructive sleep apnea/hypopnea when the pharyngeal muscles were rendered hypotonic by applying continuous positive airway pressure to the nasal airway. AVP, determined by endoscopic imaging, was significantly greater at onset of VI limitation than at minimum oropharyngeal pressure (P < 0. 01). Snoring was never observed during VI limitation. In a subgroup of six patients, values for DeltaP, VI, and AVP were obtained at 0. 1-s intervals at various levels of mask pressure. For these six patients, the mathematical expression VI = 0.657(AVP/Amax) . DeltaP0. 332, where Amax is maximal AVP, described the relationship among the three variables (R2 = 0.962) for flow-limited and non-flow-limited inspirations. The impedance of the passive velopharynx, defined as DeltaP0.33/V, was inversely related to AVP and increased dramatically when AVP was <0.3 cm2. In summary, we observed a progressive decrease in AVP during flow-limited inspiration in patients with obstructive sleep apnea. This constriction of the velopharynx contributes to an increase in velopharyngeal impedance that, in turn, counterbalances the increase in DeltaP during flow limitation.

Adult↗
PubMed1997

Reduction in blood culture contamination rate by feedback to phlebotomists.

OBJECTIVE: To determine whether monitoring and feedback of blood culture contamination rates to phlebotomists would reduce the overall contamination rate. DESIGN: Before and after interventional study. SETTING: Blood cultures collected by venipuncture by phlebotomists at Foothills Hospital, Calgary, a tertiary care teaching hospital. INTERVENTION: Feedback of contamination rates calculated from a laboratory definition of blood culture contamination. The definition was based on isolation of typical skin organisms from a single blood sample when two samples were obtained. MAIN OUTCOME MEASURE: Reduction in the laboratory-defined contamination rate in the second year. RESULTS: Of 8462 cultures collected by phlebotomists in the prefeedback year, 224 (2.6%) were contaminated, compared to 131 (1.4%) of 9282 cultures in the postfeedback year. There was a rise in the total number of positive cultures regarded as significant but a fall in the number of coagulase-negative staphylococci that were regarded as significant by our definition. The rate of contamination in blood cultures collected by nonphlebotomists did not change. CONCLUSIONS: The contamination rate decreased after feedback. Our definition of contamination was imperfect and could be improved, but it was valuable in achieving a real reduction in blood culture contamination.

Bacteria↗
PubMed1996

Aging and heparin-related bleeding.

BACKGROUND: Many studies have suggested that elderly patients are at increased risk of bleeding during heparin therapy. OBJECTIVE: To establish whether the risk of bleeding in the elderly results from concomitant risk factors or is associated with the aging process itself. METHODS: One hundred ninety-nine patients who presented with proximal deep vein thrombosis were treated with a standard intravenous heparin protocol in a double-blind, randomized, prospective study. Bleeding complications were monitored. Activated partial thromboplastin times and heparin levels were assessed 4 to 6 hours after a standard intravenous heparin bolus and infusion. Heparin doses and heparin levels were also assessed after stable therapeutic heparin infusion rates were established. RESULTS: There was an increase in total and major bleeding complications with aging (P < .05) that was not accounted for by standard risk factors for bleeding. Aging was associated with an increase in heparin levels (r = .239, P = .003) and a tendency for an increase in activated partial thromboplastin time (r = .134, P = .07) after standard heparin doses. Aging was also associated with lower heparin dose requirements (r = .267, P = .003) after therapeutic activated partial thromboplastin times were achieved. CONCLUSION: Aging is a risk for heparin-related bleeding that may be explicable by age-related changes in the pharmacologic characteristics of heparin.

Adult↗
PubMed1996

Zidovudine absorption and small intestinal function in HIV seropositive patients.

Zidovudine absorption was evaluated in HIV seropositive patients with (n = 15) and without diarrhoea (n = 20) in a standardised prospective pharmacokinetic study using single oral 200 mg doses. Zidovudine was rapidly absorbed with large peak variation (Cmax: 1.10 +/- 0.43 mg/L). There were no significant associations between pharmacokinetic parameters and presence of diarrhoea, CD4 counts, red blood cell folate concentrations, stool cultures/leucocytes or the lactulose/mannitol absorption test. Mean diarrhoea AUC (mg/L.h) was 1.13 +/- 0.30 and 1.07 +/- 0.36 in non-diarrhoeal patients. Antidiarrhoeals increased AUC and Cmax values in a small, non statistically significant subset of diarrhoea patients. Although zidovudine absorption varies significantly, our data do not support dosage individualisation based on any of the above parameters.

Administration, Oral↗
PubMed1996

Nonrespiratory predictor of mechanical ventilation dependency in intensive care unit patients.

OBJECTIVE: To determine the role of serum albumin concentration as a predictor of mechanical ventilation dependency. DESIGN: Prospective, observation trial. SETTING: Multidisciplinary intensive care unit (ICU) in a university hospital. PATIENTS: One hundred forty-five consecutive patients who required mechanical ventilation for > 72 hrs. INTERVENTIONS: Patients were classified into five different groups based on the cause of respiratory failure. The following parameters were recorded daily: serum albumin concentration; Acute Physiology and Chronic Health Evaluation II (APACHE II) score; and fluid balance. Using multiple regression, multiple logistic regression analysis, and the Anderson-Gill proportional hazards model, we determined the metabolic factors that could help predict weaning success. MEASUREMENTS AND MAIN RESULTS: The mean length of ICU stay was 12.3 +/- 1.0 days. The duration of mechanical ventilation dependency was 10.5 +/- 1.0 days. The initial mean serum albumin concentration was 25.2 +/- 0.6 g/L. The APACHE II score on the first day of ICU stay was 19.1 +/- 0.6. Although albumin concentration was significantly lower and the APACHE II score was significantly higher in ICU nonsurvivors than in ICU survivors, albumin concentration on ICU admission was not a predictor of the length of time spent receiving mechanical ventilation. The profile of albumin concentration changes was different between weaned and mechanical ventilation-dependent patients. At the time of weaning patients from the ventilator, the median albumin concentration was higher than in those patients who continued to be supported by mechanical ventilation. This effect of albumin could not be attributed to patient fluid balance or to the severity of illness since each factor had an independent influence in predicting weaning, using the Anderson-Gill proportional hazards models. CONCLUSIONS: Initial serum albumin concentration did not necessarily predict weaning success. However, when serum albumin concentration was assessed on a daily basis, its trend was important in determining the relative chance of being successfully weaned from the ventilator. This finding suggests that albumin may be an index of the metabolic status of the patient, which could be important in determining the weanability of the patients who are mechanically ventilated for prolonged periods of time.

APACHE↗
PubMed1996

A randomized, controlled trial of nurse-midwifery care.

BACKGROUND: In 1990 a pilot nurse-midwifery program was implemented in a tertiary care hospital in a major western Canadian city. a randomized, controlled trial was conducted to determine if, when maternal and newborn patient outcomes were compared, the midwifery program was as effective as traditional, low-risk health care available in the city. METHODS: All low-risk women who requested and qualified for nurse-midwifery care were randomly assigned to an experimental or control group. RESULTS: One hundred one women received care from nurse-midwives and 93 received standard care from either an obstetrician or family physician. The rate of cesarean delivery in the nurse-midwife group was 4 percent compared with 15.1 percent in the physician group. The episiotomy rate, excluding cesarean deliveries, for the nurse-midwife group was 15.5 percent compared with 32.9 percent in the physician group. The rates of epidural anesthesia for pain relief in labor were 12.9 percent and 23.7 percent, respectively. Statistically significant differences were found ultrasound examinations, amniotomy, intravenous drug administration during labor, dietary supplements, length of hospital stay, and admission of infants to the neonatal intensive care unit. CONCLUSIONS: The results clearly support the effectiveness of the pilot nurse-midwifery program and suggest that more extensive participation of midwives in the Canadian health care system is an appropriate use of health care dollars.

Adult↗
PubMed1996

Prevalence of gastroesophageal reflux symptoms in asthma.

STUDY OBJECTIVE: To determine the prevalences of symptomatic gastroesophageal reflux (GER), reflux-associated respiratory symptoms (RARS), and reflux-associated beta-agonist inhaler use in asthmatics. DESIGN: Questionnaire-based, cross-sectional analytic survey. SETTING: Outpatient asthma and clinical research clinics attached to the University of Calgary tertiary care centre and two family practices. PATIENTS: Asthma group consisted of 109 patients referred to an outpatient asthma clinic. First control group consisted of 68 patients visiting their family physicians. Second control group consisted of 67 patients with thyroid disease, hypercholesterolemia, or diabetes participating in drug trials. RESULTS: Among the asthmatics, 77%, 55%, and 24% experienced heartburn, regurgitation, and swallowing difficulties, respectively. Symptoms were less prevalent in the control groups. At least one antireflux medication was required by 37% of asthmatics (p < 0.001, vs controls). None of the asthma medications were associated with an increased likelihood of symptomatic GER. In the week prior to completing the questionnaire, 41% of the asthmatics noted RARS, including cough, dyspnea, and wheeze and 28% used their inhalers while experiencing GER symptoms. Inhaler use correlated with the severity of heartburn (r = 0.28, p < 0.05) and regurgitation (r = 0.40, p < 0.05) CONCLUSIONS: The questionnaire demonstrated a greater prevalence of GER symptoms, RARS, and reflux-associated inhaler use in asthmatics. This excessive inhaler use may explain how GER indirectly causes asthma to worsen.

Adult↗
PubMed1996

Increased use of cardiovascular medications in seniors prescribed non-ASA non-steroidal anti-inflammatory drugs.

The objective of this study was to determine the relationship between the prescribing of non-ASA non-steroidal anti-inflammatory drugs (NANSAID) and the prescribing of select cardiovascular (CV) medications. We performed a retrospective, cross-sectional analysis of the prescribed use of these medications between December 1, 1990 and June 30, 1991 by Albertans 65 years of age and older utilizing data from the publically-funded drug benefit plan. Variables examined were: the number of individuals prescribed NANSAID and CV medications; mean daily dose for these medications; calculated relative dose; the proportion of NANSAID users prescribed CV medications compared to non-users; and the relative proportions of users of specific NANSAID prescribed CV medication. We found that 33.4% and 19.6% of Albertan seniors were prescribed CV medications and NANSAID, respectively. NANSAID users were twice as likely to be prescribed CV medications as compared to non-users. Intermediate/high dose NANSAID users were more likely to be prescribed a CV medication as compared to low-dose users. The risk of being prescribed a CV medication was highest for indomethacin and users of multiple NANSAID, while ibuprofen users had the lowest risk. We conclude that NANSAID users are more likely to be also prescribed CV medications. Subjects who consume a lower dose of NANSAID are less likely to be prescribed CV medications. For different NANSAID, there is a spectrum of risk.

Age Factors↗
PubMed1995

Soft-tissue "flaws" are associated with the material properties of the healing rabbit medial collateral ligament.

This study evaluated microscopic flaws in the healing rabbit medial collateral ligament and their significance in terms of the material properties of this ligament during healing. A gap injury was created in the midsubstance of the medial collateral ligament in the right hindlimb of 15 skeletally mature (12 months old) New Zealand White rabbits. At postoperative intervals of 3, 6, or 14 weeks, histomorphometric analysis of the flaws was carried out in subgroups of animals. The medial collateral ligaments from four of the left hindlimbs (randomly selected) were used as uninjured contralateral controls. In one histologic section of each area of scar tissue and the analogous area in the controls, specified tissue flaws (blood vessels, fat cells, hypercellular areas, loose matrix, disorganized matrix, or a combination of these) were measured by four independent and blinded observers. The results showed that the mean total area of the flaws, as a percentage of the total section, and the mean area of the largest flaw decreased with healing time in each healing group but did not achieve control values by 14 weeks. Because it was not possible to test the healing medial collateral ligaments mechanically prior to measurement of the flaws (due to the destructive nature of failure testing), the data on the flaws were compared with the material strength and stiffness of a separate series of similarly injured and mechanically tested medial collateral ligaments (data published previously). A maximum likelihood statistical analysis showed a very strong functional association between the mean area of the largest flaw and the stress at failure (p < 0.004) and between the mean flaw area as a percentage of the total section area and the elastic modulus (p < 0.001). This study therefore demonstrates that it is possible to quantify material flaws in scar tissue in rabbit medial collateral ligaments, that these flaws become smaller with healing time as the scar remodels, and that flaws are functionally associated with the material properties of the ligament in this model (larger flaws with less tensile strength and more flaws with less stiffness).

Analysis of Variance↗
PubMed1995

Human embryo implantation following in-vitro fertilization: is there a seasonal variation?

The purpose of this study was to determine whether there is a seasonal variation in implantation and pregnancy rates following natural cycle replacement of cryopreserved embryos. A total of 321 consecutive cycles were analysed. There were 59 pregnancies (18.4%) and 48 live births or ongoing pregnancies (15.0%). Indicator variables for each month and variables representing temporal cycles of 12, 6, 4, 3 and 2 months were related to outcome. In addition, an analysis of periodicity was performed. No temporal, clinical or demographic variable was significantly related to pregnancy. This study indicated that there was no clear seasonal variation in the pregnancy rate following natural cycle replacement. However, the power of this study was low, and it was estimated that 963 subjects would be required to detect a 10% seasonal difference in pregnancy rates.

Adult↗
PubMed1995

Hyperglycemia in diarrhea-associated hemolytic-uremic syndrome.

Hyperglycemia is a recognized complication of diarrhea-associated hemolytic-uremic syndrome (D + HUS). Hyperglycemia developed in 8 (6.6%) of 121 patients with D + HUS. A literature review revealed a further 11 patients with D + HUS who developed hyperglycemia. The mortality rate in this group of patients is high. Hyperglycemia is more common in patients with D + HUS uremic syndrome who are female, who have an elevated white blood cell count on admission, and who develop anuria or a central nervous system complication.

Amylases↗
PubMed1995

Government, university, and community collaboration to develop a cardiac surgery database and report of morbidity and mortality while waiting for open heart surgery.

The Provincial Advisory Committee on Cardiovascular Services was established in January of 1990 to advise concerning these services. One of the first tasks assigned was to monitor waiting times for cardiac surgery. Referring cardiologists categorized their patients into four priorities: emergency, urgent-inpatient, urgent-outpatient, and planned. Data of the southern Alberta centers for the past three years were analyzed for events while waiting for surgery. (Median time to event in days) M1=Myocardial Infarction EM=Emergency D=Day A hierarchy was used to assign the single most serious event for patients having more than one event: death>MI>readmission or change from urgent-inpatient to emergency. Events were frequent and unpredictable, particularly in outpatients. Categorization of patient suitable to wait at home for cardiac surgery is imperfect. The risk of having an event while on the waiting list is much greater for out-patients than in-patients: 12.8% (169/1323) versus 1.9% (19/1002). All adverse events for the in-patients occurred at four days--one day less than the proposed maximum waiting time. In the out-patient population, the median waiting time to experiencing adverse events ranged between 32 and 54 days. Target waiting times set by PACCS for these two categories is 14 and 56 days respectively. Total adverse events occurred to 8% of the patients on the waiting list. Median waiting time to experiencing an adverse event while on the list occurs much earlier than suspected: four days in urgent in-patients and 36 days for out-patients; well below the intended maximum of 56 days. This database proved invaluable for this important critical data collection. It is hoped it will serve as a model for similar future projects.

Alberta↗