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Biomedical subjects

N Edwards

Publications and source records attributed to N Edwards.

At least 55 records · Page 3Linked to original sources
PubMed1999

Surgical management of the patient with an implanted cardiac device: implications of electromagnetic interference.

OBJECTIVE: To identify the sources of electromagnetic interference (EMI) that may alter the performance of implanted cardiac devices and develop strategies to minimize their effects on patient hemodynamic status. SUMMARY BACKGROUND DATA: Since the development of the sensing demand pacemaker, EMI in the clinical setting has concerned physicians treating patients with such devices. Implanted cardiovertor defibrillators (ICDs) and ventricular assist devices (VADs) can also be affected by EMI. METHODS: All known sources of interference to pacemakers, ICDs, and VADs were evaluated and preventative strategies were devised. RESULTS: All devices should be thoroughly evaluated before and after surgery to make sure that its function has not been permanently damaged or changed. If electrocautery is to be used, pacemakers should be placed in a triggered or asynchronous mode; ICDs should have arrhythmia detection suspended before surgery. If defibrillation is to be used, the current flow between the paddles should be kept as far away from and perpendicular to the lead system as possible. Both pacemakers and ICDs should be properly shielded if magnetic resonance imaging, positron emission tomography, or radiation therapy is to be used. The effect of EMI on VADs depends on the model. Magnetic resonance imaging adversely affects all VADs except the Abiomed VAD, and therefore its use should be avoided in this population of patients. CONCLUSIONS: The patient with an implanted cardiac device can safely undergo surgery as long as certain precautions are taken.

Clinical Protocols↗
PubMed1999

Haemodynamic responses to obstructive sleep apnoeas in premenopausal women.

OBJECTIVES: Obstructive apnoeas during sleep are associated with marked cyclical blood pressure fluctuations in men with obstructive sleep apnoea (OSA). Haemodynamic responses to OSA in women are largely unknown. We aimed to investigate haemodynamics during apnoeic events in women with OSA and to assess the influence of the menstrual cycle on these responses. DESIGN AND METHODS: Full overnight polysomnography and continuous non-invasive blood pressure monitoring was performed in 13 women with OSA during follicular and luteal phases of the menstrual cycle. Change in blood pressure (deltaBP) from pre- to post-apnoea termination was measured for each apnoeic cycle. RESULTS: Only 10 of 13 subjects ovulated. In women who ovulated, pressor responses to apnoea termination occurred in both non-rapid eye movement (NREM) and rapid eye movement (REM) sleep, but substantially increased during the luteal phase of ovulatory cycles [NREM change in mean arterial pressure (deltaMAP) 12 +/- 3 mmHg during the follicular phase and 20 +/- 3 mmHg during the luteal phase, P < 0.001; REM deltaMAP 11 +/- 3 mmHg during the follicular phase and 23 +/- 3 mmHg during the luteal phase, P < 0.001]. Sleep apnoea severity did not change during the cycle in NREM sleep, but was reduced in REM during the luteal phase. Changes in pressor responses were absent in non-ovulating subjects. CONCLUSIONS: Obstructive apnoeas in women were associated with marked blood pressure changes, similar to those previously reported in men. While respiratory events improved slightly in the luteal phase, blood pressure responses to these events increased by approximately 100%. Thus, the menstrual cycle has discordant effects on the respiratory and cardiovascular effects of OSA in women.

Adult↗
PubMed1999

Changes in Canadian women's mammography rates since the implementation of mass screening programs.

OBJECTIVES: This study reports on Canadian mammography rates between 1990, when mass screening programs were launched, and 1994/95. METHODS: Mammography rates from 2 national surveys were compared according to the presence of a provincial screening program. RESULTS: Mammography rates among women aged 50 to 69 years (the targeted group) increased significantly, by 16%; increases were twice as high in provinces with screening programs. Among women in their 40s (nontargeted group), the changes were insignificant and independent of screening program status. CONCLUSIONS: Screening programs appear to have influenced the mammography rates of targeted women aged 50 to 69 years.

Adult↗
PubMed1999

The incidence of T2-weighted MR imaging signal abnormalities in the brain of cocaine-dependent patients is age-related and region-specific.

BACKGROUND AND PURPOSE: Cocaine and its metabolites can produce vasospasm, and cocaine-dependent patients are at increased risk for stroke. Based on previous case reports, we hypothesized that the incidence of hyperintense brain lesions observed on T2-weighted MR images would also be increased in asymptomatic cocaine-dependent individuals. METHODS: Sixty-two male "crack" (smoked) cocaine-dependent participants ranging in age from 25 to 66 years were compared with 116 normal male control participants ranging in age from 25 to 80 years. Those with histories of neurologic symptoms or illnesses were excluded. The severity of hyperintense lesions was rated on a 0- to 3-point scale, and ratings of 3 were used in the data analysis as an indicator of a probable pathologic process. Three regions were separately rated: the cerebral white matter, insular subcortex white matter, and subcortical gray matter (basal ganglia and thalamus region). RESULTS: Significantly increased risk of severe lesions was observed in the two white matter regions of the cocaine-dependent group (odds ratio of 16.7 and 20.3) but not in the subcortial gray matter region (odds ratio of 1.4). In the insula subcortex white matter, the risk of lesions increased with age in the cocaine-dependant sample, but remained essentially absent among normal controls through the age of 80 years. In the cerebral white matter, the relationship of age and risk of lesion among normal participants was similar in shape to that in cocaine-dependent participants, but equivalent risk was seen 20 years earlier among cocaine-dependent participants. CONCLUSIONS: Cocaine-dependent participants had a significantly increased age-related risk of white matter damage. The possible clinical implications of this damage are discussed.

Adult↗
PubMed1998

Hospitals. Models of perfection.

Small general hospitals can adapt to changing demands in a number of ways. These include expanding day-case work and increasing outpatient services. Small hospitals could concentrate on elective surgery, or provide a full surgical service for a limited time each week, such as three days. Small ex-general hospitals could be used to provide rehabilitation services and beds for patients who do not need to be looked after in an acute hospital.

Ambulatory Care↗
PubMed1998

Differential effects of three radiographic contrast media on platelet aggregation and degranulation: implications for clinical practice?

We have determined the effects of three radiographic contrast media on platelet aggregation and degranulation in vitro. Aggregation was measured as loss of single platelets, and degranulation was measured as P-selectin expression using flow cytometry. Iopamidol added to hirudinized blood induced aggregation directly and also potentiated that induced by weak platelet agonists such as adenosine diphosphate (ADP). Iodixanol also potentiated platelet aggregation, but ioxaglate inhibited it. Iopamidol also caused marked platelet degranulation. The pro-aggregatory effect of iopamidol was evident in non-anticoagulated blood as well as in hirudinized blood, but not in citrated blood. In platelet-rich plasma (PRP) prepared from hirudinized blood neither iopamidol nor iodixanol directly induced platelet aggregation, but they rendered platelets hypersensitive to ADP. ADP antagonists inhibited the platelet aggregation and degranulation induced by iopamidol in whole blood, whereas aspirin, an inhibitor of thromborane A2 synthesis, did not. These data are consistent with clinical reports of increased thromboembolic risk with non-ionic low-osmolar media, and raise concerns about the routine use of these contrast media during diagnostic and interventional arteriographic procedures. Routine use of citrate in previous experiments may have masked a pro-aggregatory effect of some contrast media.

Adenosine Diphosphate↗
PubMed1998

Smoking and smoking relapse during pregnancy and postpartum: results of a qualitative study.

BACKGROUND: The purpose of this study was to describe women's smoking experience during pregnancy and postpartum. Primiparous women recruited during a randomized controlled trial to assess the effectiveness of postpartum visiting were invited to participate in a qualitative study. METHODS: A semistructured protocol guided the face-to-face interview. Interviews were audiotaped and transcribed. Data were coded independently by the authors, and the final coding system for emergent themes was developed through a consensus process. RESULTS: Of the 47 women invited to participate, 22 agreed to be interviewed. Three major themes emerged from the analysis: pregnancy as a context for stopping smoking, returning to smoking, and social pressures on smoking behavior. Concerns about the baby's health were cited as central reasons for stopping. Breastfeeding provided a reason for continued smoking cessation, whereas social events often demarcated a resumption of women's smoking choices. CONCLUSIONS: Results provide guidance for the timing and content of interventions to prevent smoking relapse.

Adult↗
PubMed1998

Exploring seniors' views on the use of assistive devices in fall prevention.

Falls are a common barrier to independent living among elderly persons. In recent years, growing awareness of the incidence of falls has led to the development of many community-based fall prevention programs for older adults. However, the potential impact of these programs is diminished by the lack of research on factors that may influence older persons' decisions to adopt or reject fall prevention behaviors. This exploratory descriptive study employed a focus group approach to elicit qualitative data on seniors' views on the use of assistive devices in fall prevention. Four focus group interviews were conducted with a convenience sample of 30 community-living older adults from Italian- and British-Canadian backgrounds in Ottawa, Canada. The interviews documented personal experiences with and the meaning of falls, aging, and assistive device use for older adults. The findings have important implications for the public health nursing practice in the realms of individual counseling, social marketing, and policy change to prevent falls among elderly persons. The study also provides direction for future research on this topic.

Accidental Falls↗
PubMed1998

Smoking in pregnancy and postpartum: relationship to mothers' choices concerning infant nutrition.

The objective of this study was to examine the relationship between maternal smoking status and infant nutrition. Women delivering in 5 hospitals in the Ottawa-Carleton region of Ontario were screened for eligibility over a 6-month period in 1993. Follow-up data were collected by telephone at 3 months postpartum using a validated questionnaire. Mothers were retrospectively asked about their infant-feeding choices and their smoking behaviours. Logistic regression analyses were used to determine the significance of demographic factors and maternal smoking behaviours in relationship to 3 feeding practices: bottlefeeding at birth, discontinued breastfeeding by 12 weeks, and introduction of solids by 12 weeks. A total of 796 women participated in the longitudinal study (90% follow-up rate). Less-educated; younger; single, separated or divorced; and foreign-born mothers were more likely to bottlefeed at birth. Less-educated women more often discontinued breastfeeding before 12 weeks. Mothers who had smoked during part or all of their pregnancy and were smoking at the time of the interview were significantly more likely than non-smokers to bottlefeed at birth or to discontinue breastfeeding by 12 weeks. Current smokers were also more likely than non-smokers to have introduced solid food by 12 weeks. Maternal smoking was a significant predictor of infant nutrition, with other sociodemographic factors taken into account. Smoking status should be included in clinical screening tools for infant nutrition. The relationship between other dimensions of maternal smoking (e.g., timing of quitting attempts, degree of partner support, partner's smoking behaviours) and infant-feeding practices warrants investigation.

Adolescent↗
PubMed1998

Home care case management. Perspectives from the home front.

Focus groups were held with home care case managers in two cities in Canada which provided information on the role of the case manager, factors that influence decision making, recent changes that have taken place in case management, and the different and positive aspects of home care case management. Factors which influence decision making were grouped into organizational, client, family, other professionals, and case management factors. The differences in case managers' preparation and functions in the two sites are discussed. The difficult aspects of case management included making tough decisions related to client resources, and client, work life, and management issues. The positive aspects included the personal interaction with clients, the opportunity to follow through on services to clients, the diversity of case management work, and the opportunity for relatively independent professional practice.

Attitude of Health Personnel↗