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Biomedical subjects

W W Flemons

Publications and source records attributed to W W Flemons.

18 recordsLinked to original sources
PubMed2006

Burden of community-onset bloodstream infection: a population-based assessment.

Although community-onset bloodstream infection (BSI) is recognized to be a major cause of morbidity and mortality, there is a paucity of population-based studies defining its overall burden. We conducted population-based laboratory surveillance for all community-onset BSI in the Calgary Health Region during 2000-2004. A total of 4467 episodes of community-onset BSI were identified for an overall annual incidence of 81.6/100,000. The three species, Escherichia coli, Staphylococcus aureus, and Streptococcus pneumoniae were responsible for the majority of community-onset BSI; they occurred at annual rates of 25.8, 13.5, and 10.1/100,000, respectively. Overall 3445/4467 (77%) episodes resulted in hospital admission representing 0.7% of all admissions to major acute care hospitals. The subsequent hospital length of stay was a median of 9 (interquartile range, 5-15) days; the total days of acute hospitalization attributable to community-onset BSI was 51,146 days or 934 days/100,000 annually. Four hundred and sixty patients died in hospital for a case-fatality rate of 13%. Community-onset BSI is common and has a major patient and societal impact. These data support further efforts to reduce the burden of community-onset BSI.

Adolescent↗
PubMed2005

Post-endoscopy checklist reduces length of stay for non-variceal upper gastrointestinal bleeding.

OBJECTIVE: To examine the effect of improved gastroenterologist-to-admitting service communication on hospital stay for upper gastrointestinal bleeding. HYPOTHESIS: a detailed checklist addressing factors relevant to discharge planning would shorten hospital stay, when added to the procedure report. DESIGN: Pre-post intervention design, recording balance measures (potential confounders). SETTING: A Canadian university hospital. STUDY PARTICIPANTS: Intermittent 5- to 7-day batches of consecutive emergency patients presenting with non-variceal upper gastrointestinal bleeding as their primary problem. The durations of the background and intervention periods were 3 months (beginning 9 June 2003) and 4 weeks (beginning 8 September 2003), respectively. INTERVENTION: The gastrointestinal bleeding Quality Improvement and Health Information multidisciplinary team (quality improvement personnel; emergency physicians, hospitalists, gastroenterologists, in-patient and endoscopy nurses) developed a one-page checklist, outlining detailed recommendations (3-Ds-diet, drugs, discharge plan) to append to the procedure report. MAIN OUTCOME MEASURES: Difference in median length of hospital stay was the primary endpoint. As balance measures, demographics, bleeding severity, comorbidities, readmission rates, and various benchmark times were recorded prospectively. RESULTS: Thirty-nine patients met the criteria in the background period (4 months, intermittently sampled), and 22 in the intervention period (4 weeks, continuously sampled). There were no significant baseline differences. Median in-patient stay was 7.0 (95% interquartile range 2-24) versus 3.5 (95% interquartile range 1-12) days for the background and intervention periods, respectively (P = 0.003). This remained significant when outliers (stay > 10 days) were removed (P = 0.02). CONCLUSION: A checklist, with very specific recommendations to the admitting service, significantly reduced hospital stay for non-variceal gastrointestinal bleeding.

Admitting Department, Hospital↗
PubMed2001

Evidence-based medicine and sleep apnea.

There is an increasing body of evidence that obstructive sleep apnea (OSA) affects systemic blood pressure and quality of life. The evidence linking OSA with other types of cardiovascular morbidity and mortality is not as strong. We review the current literature on the health impact, diagnosis, and treatment of OSA and provide a framework for evaluating levels of evidence in each of these areas, with the focus on high quality studies. Clinical prediction rules and unattended portable monitoring devices, such as digital oximeters, are inexpensive and have clinically useful likelihood ratios, sensitivity, and specificity, so they can be considered clinically useful in the evaluation of individuals suspected of having OSA. This approach has the potential to change the probability of disease in some patients to a level at which polysomnography is unnecessary. Recent randomized, placebo-controlled trials have indicated that treating OSA with continuous positive airway pressure improves quality of life, driving simulator performance, blood pressure, and sleepiness. The evidence in support of mandibular advancement is less strong, and surgical measures should be viewed as an option only after continuous positive airway pressure and mandibular advancement have been considered, given the paucity of evidence to support surgery. The quality of research done on the prognosis, diagnosis, and treatment of OSA has improved substantially in recent years. However, there remains a need for additional studies that evaluate ambulatory monitors and for larger randomized controlled trials of therapy with longer patient follow-up to verify the range of benefits that OSA patients can expect from the various treatment modalities.

Evidence-Based Medicine↗
PubMed2000

Sleep-disordered breathing in Duchenne muscular dystrophy: a preliminary study of the role of portable monitoring.

Although Duchenne muscular dystrophy (DMD) is often associated with sleep disordered breathing (SDB), it is not standard clinical practice to routinely test this population for SDB, and the optimal timing and methodology for such testing has not been established. Our objectives were: 1) to examine the concordance between laboratory polysomnography (PSG) and two portable monitoring systems, and 2) to identify clinical factors associated with the onset of SDB. We performed a cross-sectional pilot study of patients with DMD who were 6 years of age or older, and who were registered at the Alberta Children's and Calgary General Hospitals. Patient symptom and functional rating scores were calculated, and pulmonary function tests, awake oxygen saturation, and capillary blood gases were obtained. PSG was performed according to standard methods, and results were compared with Snoresat(R) (Saga Tech Electronics, Inc.) and EdenTec(R) (Nellcor Puritan Bennett) portable home monitors. Eleven boys were studied. Ten of 11 subjects had normal awake oxygen saturation and capillary blood gases. Median forced vital capacity (FVC) was 70% of predicted values (15-104%). PSG identified 3 boys with severe hypoventilation occurring throughout REM sleep. Reported symptom severity did not predict the patients with significant SDB. All 3 boys with SDB had a severe functional disability and severely reduced FVCs. Portable monitoring in the home identified all patients with abnormal PSG. One additional patient was falsely identified by the EdenTec(R) monitor. We conclude that initial results using Snoresat(R) or EdenTec(R) monitoring equipment for the identification of SDB are promising, but further validation of portable home monitoring is required in this group of patients.

Adolescent↗
PubMed2000

Automated analysis of digital oximetry in the diagnosis of obstructive sleep apnoea.

BACKGROUND: The gold standard diagnostic test for obstructive sleep apnoea (OSA) is overnight polysomnography (PSG) which is costly in terms of time and money. Consequently, a number of alternatives to PSG have been proposed. Oximetry is appealing because of its widespread availability and ease of application. The diagnostic performance of an automated analysis algorithm based on falls and recovery of digitally recorded oxygen saturation was compared with PSG. METHODS: Two hundred and forty six patients with suspected OSA were randomly selected for PSG and automated off line analysis of the digitally recorded oximeter signal. RESULTS: The PSG derived apnoea hypopnea index (AHI) and oximeter derived respiratory disturbance index (RDI) were highly correlated (R = 0.97). The mean (2SD) of the differences between AHI and RDI was 2.18 (12.34)/h. The sensitivity and specificity of the algorithm depended on the AHI and RDI criteria selected for OSA case designation. Using case designation criteria of 15/h for AHI and RDI, the sensitivity and specificity were 98% and 88%, respectively. If the PSG derived AHI included EEG based arousals as part of the hypopnea definition, the mean (2SD) of the differences between RDI and AHI was -0.12 (15. 62)/h and the sensitivity and specificity profile did not change significantly. CONCLUSIONS: In a population of patients suspected of having OSA, off line automated analysis of the oximetry signal provides a close estimate of AHI as well as excellent diagnostic sensitivity and specificity for OSA.

Adult↗
PubMed1999

A comparison of apnea-hypopnea indices derived from different definitions of hypopnea.

We examined the effects of arousal- and desaturation-based scoring criteria on the apnea-hypopnea index (AHI) and on the measured prevalence of obstructive sleep apnea (OSA). Ninety-four randomly selected patients underwent overnight polysomnography. Studies were scored according to three different criteria for hypopnea, as defined by a >= 10 s discernible reduction in thoracoabdominal movement associated with: (1) >= 4% decrease in oxygen saturation (SaO2) (Type A); (2) either a >= 4% decrease in SaO2 or an arousal (Type B); or (3) electroencephalographically based arousal alone (Type C). Excellent correlation existed between AHI-A, AHI-B, and the oxygen desaturation index (ODI) (r > 0.98). AHI-A and AHI-B differed by only 2.04 +/- 1.72/h (2 SD). AHI-A and AHI-B differed from the ODI by 1.04 +/- 4.07/h and 3.07 +/- 4.30/h, respectively. Despite these small differences, use of the Type B rather than Type A definition resulted in an extra case of OSA being diagnosed for every 14 to 31 patients tested, depending on the definition of OSA (AHI: >= 5, 10, 15, or 20/h). The addition of arousal-based scoring criteria for hypopnea causes only small changes in the AHI, but if OSA is defined solely by an AHI value, the measured prevalence of OSA will increase.

Adult↗
PubMed1998

Development of a disease-specific health-related quality of life questionnaire for sleep apnea.

The Calgary Sleep Apnea Quality of Life Index (SAQLI) was developed to record key elements of the disease that are important to patients. All items felt to influence the quality of life of these patients were identified. Final questionnaire items were selected by interviewing 113 patients with sleep apnea and 50 snorers who rated each item on whether it was a problem and the importance of it to their overall quality of life. Items for the final questionnaire were selected based on the rank order of the frequency ximportance product. The rank ordering was similar across strata of disease severity and between sexes. The Calgary SAQLI has 35 questions organized into four domains: daily functioning, social interactions, emotional functioning, and symptoms. A fifth domain, treatment-related symptoms, can be added for clinical intervention trials to record the possible negative impacts of treatment. The SAQLI has a high degree of internal consistency, face validity as judged by content experts and patients, and construct validity as shown by its positive correlations with the SF-36 and the improvement in scores in patients successfully completing a 4-wk trial of continuous positive airway pressure. It includes items shown to be important to patients with sleep apnea and is designed as a measure of outcome in clinical trials in sleep apnea. Flemons WW, Reimer MA. Development of a disease-specific health-related quality of life questionnaire for sleep apnea.

Adult↗
PubMed1997

Quality of life consequences of sleep-disordered breathing.

Sleep-disordered breathing occurs in approximately 2% to 4% of the adult population and includes conditions in which patients stop breathing completely (apnea) or have marked reductions in airflow (hypopnea) during sleep. Typical symptoms of sleep apnea include snoring, restless sleep, excessive daytime somnolence, nocturnal enuresis, irritability, depression, memory deficits, inability to concentrate, and decreased alertness. The clinically relevant outcomes of these symptoms include impairment in work efficiency, increased automobile accident rates, and decrements in quality of life. Treatment of sleep apnea, primarily with continuous positive airway pressure, reduces sleepiness and improves mood disturbances, neurocognition, and performance. Traditional measurements of sleep apnea severity do not correlate well with current tests and scales that are used to quantify alterations in alertness, performance, quality of life, or sleepiness. A disease-specific quality of life scale has been developed following patient and physician interviews and literature reviews. The Calgary Sleep Apnea Quality of Life Index is expected to capture aspects of quality of life important to sleep apnea patients, such as cognitive function, performance, and mood, that could be improved with appropriate treatment of sleep-disordered breathing.

Accidents, Traffic↗
PubMed1996

Polysomnography: addressing the need for standards.

The field of sleep disorders medicine is facing enormous challenges as it strives to gain recognition from the medical profession, the public and government. One of these challenges is to ensure that limited resources for diagnosis are used wisely. The authors argue that the standards for polysomnography developed by the Canadian Sleep Society and the Canadian Thoracic Society (see pages 1673 to 1678 of this issue) will go a long way toward ensuring that this expensive resource is used prudently. In the mean-time, more research is needed to determine valid measures of the impact of sleep disorders and to establish the reliability of different diagnostic methods.

Canada↗
PubMed1996

The diagnosis of sleep apnea: questionnaires and home studies.

Alternatives to the standard method of diagnosing sleep apnea (SA) are becoming increasingly popular due to the expense and/or. In some cases, the limited availability of polysomnography (PSG). The most common diagnostic alternatives have been clinical prediction rules and portable monitoring. Most portable monitors record one or more signals such as oxygen saturation, heart rate, airflow, or ribcage and abdominal movements. To date, most published studies of these monitors have had serious methodologic problems that have limited the acceptance of this technology. We have developed a two-step diagnostic approach for SA based on a clinical prediction rule and the results from a simple, but reliable and accurate, portable monitor that records oxygen saturation, snoring, and body position. The preliminary results indicate that such a strategy is very useful in a population of outpatients suspected of having SA and would preclude the need for PSG to investigate for this possibility in the majority of patients. However, before portable monitoring becomes widely adopted, each system should be more thoroughly tested, and increased attention should be directed at the design of the study so that the results are more generalizeable to other sleep clinic populations.

Algorithms↗
PubMed1994

Likelihood ratios for a sleep apnea clinical prediction rule.

Nocturnal polysomnography, the standard diagnostic test for sleep apnea, is an expensive and limited resource. In order to help identify the urgency of need for treatment, we determined which clinical features were most useful for establishing an accurate estimate of the probability that a patient had sleep apnea. Of 263 physician-referred patients, 200 were eligible for the study and 180 (90%) completed it. All patients had their histories recorded with a standard questionnaire, and underwent anthropomorphic measurements and nocturnal polysomnography. Sleep apnea was defined as more than 10 episodes of apnea or hypopnea per hour of sleep. Multiple linear and logistic regression models predictive of sleep apnea were compared with physicians' subjective impressions and previously reported models. Likelihood ratios were calculated for several levels of a sleep apnea clinical score produced by one of the linear models. Predictors of sleep apnea in the final model (R2 = 0.34) included neck circumference, hypertension, habitual snoring, and bed partner reports of nocturnal gasping/choking respirations. This model was superior to physician impression, slightly inferior to more detailed linear and logistic models, and comparable to previously reported models. A sleep apnea clinical score of less than 5 had a likelihood ratio of 0.25 (95% CI: 0.15 to 0.42) and a corresponding posttest probability of 17%, while a score of greater than 15 had a likelihood ratio of 5.17 (95% CI: 2.54 to 10.51) and posttest probability of 81%. These likelihood ratios can simply and accurately determined the probability of whether a patient has sleep apnea.

Adult↗
PubMed1993

Sleep apnea and cardiac arrhythmias. Is there a relationship?

To determine if there was a relationship between cardiac arrhythmias and sleep apnea, we studied the prevalence of arrhythmias in a consecutive series of patients referred to our clinic for assessment of this disorder. Two hundred of 263 physician-referred patients were eligible for the study and, of these, 173 (86.5%) had complete investigations. All patients underwent a full night of polysomnography and Holter monitoring. Sleep apnea was diagnosed if patients had more than 10 apneas and hypopneas per hour (AHI). In 76 patients (43.9%) sleep apnea was diagnosed (median AHI = 33). The prevalence of arrhythmias in patients with sleep apnea versus those without was, respectively: complex ventricular ectopy (including ventricular tachycardia), 1.3% (95% CI, 0.4 to 6.9) versus 4.1% (CI, 1.6 to 10.1); frequent ventricular premature beats (> 30/h), 2.6% (CI, 0.8 to 8.9) versus 6.2% (CI, 2.9 to 12.8); second-degree atrioventricular block, 1.3% (CI, 0.4 to 6.9) versus 4.1% (CI, 1.6 to 10.1); sinus arrest, 5.2% (CI, 2.2 to 12.6) versus 1.0% (CI, 0.2 to 5.6). None of these differences was statistically significant. We conclude that the prevalence of cardiac arrhythmias is low in patients without serious cardiac or respiratory comorbidity who are referred for assessment of sleep apnea. Furthermore, the presence or absence of arrhythmias in this group is unrelated to sleep apnea severity.

Adult↗
PubMed1986

Alcohol dependence and withdrawal in the rat. An effective means of induction and assessment.

Numerous problems have been associated with previous attempts to develop a suitable method for the induction and assessment of alcohol dependence and withdrawal syndrome in the rat. Using our modification of a common inhalation method for the long-term administration of ethanol, these problems can be eliminated. Adult male rats (Long Evans and Brattleboro) were exposed to ethanol vapor concentrations of 7 to 35 mg/liter of air, which cause rapid development of tolerance and physical dependence. With this inhalation method, it is possible to obtain and easily maintain high levels of ethanol in the blood (150 to 400 mg/dl). When exposure to ethanol is terminated, ethanol is eliminated from the system within 1 to 6 hr. This rapid elimination of ethanol is accompanied by a high susceptibility to withdrawal reactions. The severity of the withdrawal syndrome was assessed within 6 to 24 hr after cessation of the ethanol administration by exposing each rat individually to a 60 to 120-sec period of bell ringing. Convulsive seizures were observed in nearly 90% of the animals tested, with a mortality rate of less than 20%.

Acoustic Stimulation↗
PubMedDate not supplied

The role of arginine vasopressin in alcohol dependence and withdrawal.

The development and maintenance of tolerance to the physiological and behavioral effects of repeated exposure to ethanol can be altered markedly by the presence of arginine vasopressin (AVP). In addition, AVP has been implicated in the etiology of convulsions, including those induced by exposure to high ambient temperatures. In light of these findings, experiments were conducted to determine the role, if any, that AVP might play in the pathogenesis of alcohol-withdrawal convulsions. Thirty-two male Long Evans (LE) rats and 32 age-matched male homozygous Brattleboro (DI) rats (genetically deficient in AVP) were exposed to ethanol vapor concentrations adjusted to maintain blood alcohol levels of each rat at 150-350 mg/dl. Following at least 5 days of ethanol exposure, the animals were withdrawn. From 3-24 hr after cessation of ethanol administration, withdrawal severity was assessed by observing the response of each animal to a 60-120 sec period of auditory stimulation. No significant differences were observed in either latency to onset or severity of the convulsions in LE and DI rats upon ethanol withdrawal. Thus, alcohol-withdrawal convulsions, unlike hyperthermia-induced convulsions, may be mediated by a neurochemical substrate other than AVP.

Alcoholism↗