Sharon Chung - Academia.edu (original) (raw)

Papers by Sharon Chung

Research paper thumbnail of Risk of obstructive sleep apnea in open-angle glaucoma versus controls using the STOP-Bang questionnaire

Canadian journal of ophthalmology. Journal canadien d'ophtalmologie, Feb 1, 2018

To compare the percentage of patients at risk for obstructive sleep apnea (OSA) in open-angle gla... more To compare the percentage of patients at risk for obstructive sleep apnea (OSA) in open-angle glaucoma (OAG) versus controls using the STOP-Bang questionnaire. This study used a cross-sectional survey. Patients with OAG and controls completed the STOP-Bang questionnaire-a validated tool to identify patients at high risk for OSA. Patients were considered at risk if they scored 3 or more points or at high risk for moderate/severe OSA if they scored 5 or more out of the maximum 8 points. Demographic information, medical history, and previous diagnosis of OSA were recorded. Details regarding the patients' glaucoma were obtained from their medical records. A total of 437 patients with OAG and 441 controls were included. The mean STOP-Bang score was 3.01 ± 1.3 for the glaucoma group and 3.03 ± 1.4 for the control group (p = 0.92). There was no significant difference between the percentage of subjects considered at risk for OSA (62.7% OAG vs 59.4% controls, p = 0.37) or at high risk fo...

Research paper thumbnail of A comparison of two screening tools for paediatric obstructive sleep apnea

Journal of Sleep Research

Untreated obstructive sleep apnea in children is associated with significant medical and psycholo... more Untreated obstructive sleep apnea in children is associated with significant medical and psychological morbidities. Polysomnographic testing is the gold-standard method for diagnosis of obstructive sleep apnea. However, laboratory-based polysomnography is expensive and associated with a substantial healthcare burden. Thus, a simple valid tool to accurately identify those at high risk of obstructive sleep apnea is essential. We performed a retrospective cross-sectional study of children referred to the Youthdale Child and Adolescent Sleep Clinic. Data were collected from questionnaires and sleep studies reports of 395 children. A comparison between two screening tools for paediatric obstructive sleep apneaa sixitem (parent-response) and an eight-item IF-SLEEPY/IM-SLEEPY scales was performed. The results showed that 42% of the children (n = 164) were diagnosed with obstructive sleep apnea. The six-item scale (score ≥3) exhibited a sensitivity of 17% and a specificity of 95% for diagnosing obstructive sleep apnea. The eight-item IF-SLEEPY scale displayed 82% sensitivity and 28% specificity. The IM-SLEEPY scale exhibited 79% sensitivity and 32% specificity. In children ≥7 years old, the IF-SLEEPY (parent-response) had a sensitivity of 82% and specificity of 28% compared with the child-response (66% and 37%, respectively). Logistic regression analysis revealed that age (odds ratio = 0.78), IF-SLEEPY/IM-SLEEPY score ≥3 (odds ratio = 1.78) and a score ≥2.72 on the six-item scale (odds ratio = 4.54) were predictors of obstructive sleep apnea. This study suggests that the eight-item scale is a better screening tool for paediatric obstructive sleep apnea, with a higher sensitivity and simple yes/no responses that are easy to complete and to score.

Research paper thumbnail of Adrenergic blockade does not restore the canine gastric migrating motor complex during vagal blockade

Research paper thumbnail of CME A Systemic Review of Obstructive Sleep Apnea and Its Implications for Anesthesiologists

Anesthesia and Analgesia, 2008

Research paper thumbnail of Adrenergic blockage does not restore the canine gastric migrating motor complex during vagal blockade

Gastroenterology, Dec 1, 1992

Bilateral cervical cooling blockade of the vagi abolishes the gastric migrating motility complex ... more Bilateral cervical cooling blockade of the vagi abolishes the gastric migrating motility complex (MMC), except for the pylorus. The present study investigated if this finding is caused by adrenergic inhibition of the stomach via sympathetic nerves entering the vagi below the level of the blockade. Stomach and upper small bowel motor activity was monitored in five chronic dogs whose vagosympathetic nerve trunks were previously isolated in bilateral, cervical skin loops to permit blockade by cooling. Adrenergic blockade was performed by an initial bolus injection of phentolamine (0.3 mg/kg) and propranolol (0.3 mg/kg) followed by a continuous intravenous infusion of the combined drugs at a rate of 1.5 mg.kg-1.h-1 for phentolamine and 0.3 mg.kg-1.h-1 for propranolol. Bilateral cervical vagal blockade abolished the gastric MMC, with persistence of phase III of the MMC in the upper small bowel. During combined vagal and adrenergic blockade, gastric contractions were absent in 4 of the 22 duodenal complexes observed. In the other duodenal complexes, intermittent gastric contractions were associated with all phases of the intestinal MMC, including phase I. At times, this contractile activity was accentuated during phase III but never reached the intensity of activity or showed the typical coordination features of the gastric MMC seen with the vagi intact. Therefore, unopposed adrenergic inhibition of the stomach does not explain the absence of the gastric MMC during vagal cooling blockade. Under normal circumstances, the vagus nerve is the most important pathway for central control of the appearance of the gastric MMC.

Research paper thumbnail of The Vagus, Motilin, and the Migrating Motor Complex. Author's Reply

Research paper thumbnail of Moderate Exercise and Bright Light Treatment in Overweight and Obese Individuals*

Obesity, 2007

Increased physical activity is important given the concern over the growing rates of obesity. The... more Increased physical activity is important given the concern over the growing rates of obesity. The aim of this study is to conduct a controlled investigation of the effects of bright light therapy and exercise on weight loss and body composition in overweight and obese individuals. Twenty-five overweight and obese subjects were assigned to 6 weeks of moderate exercise with or without bright light treatment. Outcome measure included changes in body mass and body composition and ratings of mood, seasonality, and sleep. Body weight decreased significantly with exercise in subjects in the light and non-light treatment groups, but the change was not significantly different between the groups. Similar results were found for BMI. With exercise, body fat decreased significantly only in the light treatment group. There was a significant effect of the interaction of group by time on body fat composition, but the group by time interaction failed to reach statistical significance for body weight and BMI. Mood scores improved significantly with exercise in the light group, but no significant changes were noted regarding sleep. This preliminary study is the first to show that addition of bright light treatment to a 6-week moderate exercise program can alter body composition by significantly reducing body fat. The reduction in body fat mass is of particular importance, because visceral fat has been particularly implicated as a major factor in the development of the metabolic syndrome. This study is an important step toward finding ways to maximize the effects of exercise.

Research paper thumbnail of The Toronto Hospital Alertness Test scale: relationship to daytime sleepiness, fatigue, and symptoms of depression and anxiety

Nature and Science of Sleep, 2016

Treatment centres, 3 Youthdale child and adolescent Sleep centre,

Research paper thumbnail of Three Siblings with Prader-Willi Syndrome: Brief Review of Sleep and Prader-Willi Syndrome

Case Reports in Neurological Medicine, 2015

Prader-Willi syndrome (PWS) is a genetic disorder characterized by short stature, mental retardat... more Prader-Willi syndrome (PWS) is a genetic disorder characterized by short stature, mental retardation, hypotonia, functionally deficient gonads, and uncontrolled appetite leading to extreme obesity at an early age. Patients with this condition require multidisciplinary medical care, which facilitates a significant improvement in quality of life. PWS is the first human disorder to be attributed to genomic imprinting. Prevalence varies in the literature, ranging from 1 in 8,000 in the Swedish population to 1 in 54,000 in the United Kingdom. Rarely, the genetic mechanism responsible for Prader-Willi syndrome can be inherited. We report a highly unique case of three siblings who share this condition. This report describes a case of two brothers and one half sister with PWS. All three siblings have sleep-related complaints. The sister died at the age of 24 years in her sleep, with the cause of death reported as obstructive sleep apnea. The outcome was positive in both of the brothers’ cas...

Research paper thumbnail of Weighing the balance: how analgesics used in chronic pain influence sleep?

British journal of pain, 2014

Pain and sleep share a bidirectional relationship, with each influencing the other. Several excel... more Pain and sleep share a bidirectional relationship, with each influencing the other. Several excellent reviews have explored this relationship. In this article, we revisit the evidence and explore existing research on this complex inter-relationship. The primary focus of the article is on the pharmacological treatment of chronic non-malignant pain and the main purpose is to review the effect of various pharmacological agents used in the management of chronic pain on sleep. This has not been comprehensively done before. We explore the clinical use of these agents, their impact on sleep architecture and sleep physiology, the mechanism of action on sleep parameters and sleep disorders associated with these agents. Pharmacological classes reviewed include antidepressants, opioid analgesics, anti-epileptics, cannabinoids and non-steroidal anti-inflammatory agents, drugs most commonly used to manage chronic pain. The objective is to help health professionals gain better insight into the co...

Research paper thumbnail of How, what, and why of sleep apnea. Perspectives for primary care physicians

Canadian family physician Médecin de famille canadien, 2002

To review the need for primary care physicians to screen for patients with obstructive sleep apne... more To review the need for primary care physicians to screen for patients with obstructive sleep apnea (OSA). Literature was reviewed via MEDLINE from 1993 to 2000, inclusive, using the search term "sleep apnea" combined with "epidemiology," "outcome," and "diagnosis and treatment." Citations in this review favour more recent, well controlled and randomized studies, but findings of pilot studies are included where other research is unavailable. Obstructive sleep apnea is a disorder with serious medical, socioeconomic, and psychological morbidity, yet most patients with OSA remain undetected. Primary care physicians have a vital role in screening for these patients because diagnosis can be made only through overnight (polysomnographic) studies at sleep clinics. Physicians should consider symptoms of excessive or loud snoring, complaints of daytime sleepiness or fatigue, complaints of unrefreshing sleep, and an excess of weight or body fat distribut...

Research paper thumbnail of Home-use servo-ventilation therapy in chronic pain patients with central sleep apnea: initial and 3-month follow-up

Sleep and Breathing, 2015

Purpose Opioid treatment of non-malignant chronic pain can result in hypoxemia, hypercarbia, and ... more Purpose Opioid treatment of non-malignant chronic pain can result in hypoxemia, hypercarbia, and central sleep apnea. The aim of this study was to determine the initial efficacy of auto servo-ventilation (ASV) and after 3 months of home use. Methods This prospective multicenter interventional study recruited chronic pain patients prescribed ≥100 morphine equivalents for at least 4 months. Participants Following full-night polysomnography (PSG) to confirm the presence of sleep-disordered breathing, patients were randomized to three additional full-night-attended PSGs with continuous positive airway pressure (CPAP), ASV, and servo-ventilation with an initial mandatory pressure support of 6 cm H 2 O (ASV manual PSmin 6). Following the PSGs, patients were sent home with EncoreAnywhere and ASV with or without mandatory pressure support. Results Based on the initial PSG studies, CPAP improved but did not normalize the apnea-hypopnea index (AHI), central apnea index (CAI), or hypopnea index (HI), as all remained elevated. Clinically significant reductions were noted after just one night of ASVand ASV manual (PSmin 6). After 3 months of ASV home use, the AHI, CAI, and obstructive apnea index (OAI) were significantly reduced when compared to baseline diagnostic levels and even when compared to respiratory disturbance indices with CPAP treatment. Conclusions Initial and home use of ASV for 3 months resulted in significantly lower AHI, CAI, and OAI. This reduction attests to the efficacy of ASV treatment in chronic pain patients on high doses of opioids.

Research paper thumbnail of Sleep apnea, hypertension, and the effects of continuous positive airway pressure

American journal of hypertension, 2005

Sleep apnea is being studied as a risk factor for hypertension. This observational chart review w... more Sleep apnea is being studied as a risk factor for hypertension. This observational chart review was conducted to determine the long-term effects of continuous positive airway pressure (CPAP) treatment on blood pressure (BP) in a sample of sleep apnea patients from urban and rural populations. This study was conducted using data from 180 clinical charts from 1995 to 2002. Patients were identified as hypertensive or normotensive by their initial BP values before they were diagnosed with sleep apnea and were also reviewed after the use of CPAP. Of the patients diagnosed with sleep apnea, 32% were found to have hypertension (mean systolic BP: 164.4 +/- 20.3 mmHg; mean diastolic BP: 96.9 +/- 5.3 mmHg). The average use of CPAP was 12.1 +/- 22.4 months. The hypertensive group showed a significant reduction in BP with CPAP use: systolic BP dropped by an average of 11.2 mmHg (P < .001) and diastolic BP dropped by an average of 5.9 mmHg (P < .001). Our results confirm that frequency of ...

Research paper thumbnail of Small intestinal motility in fasted and postprandial states: effect of transient vagosympathetic blockade

The American journal of physiology, 1987

We investigated vagal control of the migrating myoelectric complex (MMC) and postprandial pattern... more We investigated vagal control of the migrating myoelectric complex (MMC) and postprandial pattern of the canine small intestine. Gastric and small intestinal motility were monitored in six conscious dogs. The vagosympathetic nerves, previously isolated in bilateral skin loops, were blocked by cooling. To feed, a meat-based liquid food was infused by tube into the gastric fundus. MMC phases I, II, III, and IV were observed in the fasted state. On feeding, the fed pattern appeared quickly in the proximal small bowel but was delayed distally. Vagal blockade abolished all gastric contractions and spiking activity as well as the small bowel fed pattern. During vagal blockade, the small bowel exhibited MMC-like migrating bursts of spikes in both the fasted and fed states. The migration and cycling of these bursts were not significantly different from the MMC, but the duodenal and jejunal phase II was absent or shortened. On termination of vagal blockade, normal fasting or fed activity rea...

Research paper thumbnail of Polysomnographic and symptomatological analyses of major depressive disorder patients treated with mirtazapine

Canadian journal of psychiatry. Revue canadienne de psychiatrie, 2006

This study aimed to characterize the effects of mirtazapine on polysomnographic sleep, especially... more This study aimed to characterize the effects of mirtazapine on polysomnographic sleep, especially slow wave sleep (SWS) and rapid eye movement (REM) sleep, as well as its effects on clinical symptoms in patients with major depressive disorder (MDD). Sixteen MDD patients were treated with mirtazapine 30 mg taken 30 minutes before bedtime. Polysomnographic and subjective sleep, as well as other clinical data, were collected at baseline and on Days or Nights 2, 9, 16, 30, and 58 during treatment. We used repeated measures analysis of variance, including pairwise comparison, to analyze data statistically. Mirtazapine administration increased total SWS and the SWS in the first sleep cycle, but not SWS in the second sleep cycle. The medication increased REM latency and the duration of the first REM episode; it also decreased the number of REM episodes. Simultaneously, mirtazapine significantly reduced wake-after-sleep onset and scores on the Athens Insomnia Scale. After patients took the ...

Research paper thumbnail of Validation of a short questionnaire in English and French for use in patients with persistent upper gastrointestinal symptoms despite proton pump inhibitor therapy: the PASS (Proton pump inhibitor Acid Suppression Symptom) test

Canadian journal of gastroenterology = Journal canadien de gastroenterologie, 2005

The management of persistent symptoms during acid suppression therapy in patients with gastroesop... more The management of persistent symptoms during acid suppression therapy in patients with gastroesophageal reflux disease or dyspepsia might be improved if patient-physician communication regarding the presence and character of these persistent symptoms were facilitated. To validate a short, simple questionnaire (the Proton pump inhibitor [PPI] Acid Suppression Symptom [PASS] test), in English and French, to identify patients with persistent acid-related symptoms during PPI therapy and document their response to a change in therapy. Patients with persistent acid-related symptoms on PPI therapy were interviewed to produce a draft, five-item questionnaire; content validity was evaluated by focus groups comprising English- and French-speaking patients. Psychometric validity was subsequently evaluated in a multicentre, family practice-based study of English- and French-speaking patients with persistent acid-related upper gastrointestinal symptoms despite PPI therapy. The PASS test, Global ...

Research paper thumbnail of Validation of a pediatric obstructive sleep apnea screening tool

International Journal of Pediatric Otorhinolaryngology, 2013

Pediatric obstructive sleep apnea (OSA) is a prevalent but under-diagnosed disease. The importanc... more Pediatric obstructive sleep apnea (OSA) is a prevalent but under-diagnosed disease. The importance of screening for OSA in every child has been recently re-emphasized by the American Academy of Pediatrics Guidelines. Although several screening questionnaires are available for pediatric OSA, they are either complicated to use or not sensitive enough, and therefore OSA is seldom screened in primary care settings. Here, we validated a previously developed short (6-item) hierarchically-based screening questionnaire tool for pediatric OSA. Parents of 85 children referred for a sleep study at a pediatric community-based sleep clinic completed the questionnaire and their children underwent an overnight PSG. Receiver operator curve analyses and other predictive scales were assessed. The 6-item questionnaire exhibited favorable sensitivity and fair specificity for diagnosis of OSA, which varied depending on the apnea-hypopnea index used for OSA definition. A 6-item questionnaire is a sensitive and easy-to-use screening tool for pediatric OSA in a pediatric sleep clinic setting.

Research paper thumbnail of I’M SLEEPY: A short pediatric sleep apnea questionnaire

International Journal of Pediatric Otorhinolaryngology, 2014

Pediatric obstructive sleep apnea (OSA) is a prevalent but under-diagnosed disease. The importanc... more Pediatric obstructive sleep apnea (OSA) is a prevalent but under-diagnosed disease. The importance of screening for OSA has been emphasized in the recently published guidelines for the diagnosis and management of childhood OSA. Several pediatric OSA questionnaires are available, but are complicated to use or not sensitive enough for screening. In this study we developed an 8-item (IF SLEEPY) screening tool for pediatric OSA. One hundred and fifty children referred for evaluation at a pediatric sleep clinic and their parents completed the questionnaire and had a polysomnography. Two further questionnaires were developed: I SLEEPY and I&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;M SLEEPY versions. The questionnaires&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; scores were compared to the apnea hypopnea index (AHI) and the validity of each questionnaire was evaluated. The I&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;M SLEEPY version was found to have the highest sensitivity (82%) and a modest specificity (50%) for OSA diagnosis. I&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;M SLEEPY is a sensitive and easy-to-use screening tool for pediatric OSA. It is intended to be used by the primary physician in every suspected case of OSA. Larger studies are needed in the primary care setting for the validation of this tool.

Research paper thumbnail of Knowledge of Sleep Apnea in a Sample Grouping of Primary Care Physicians

Sleep And Breathing, 2001

This pilot study was performed in order to examine the knowledge of four groups of primary care p... more This pilot study was performed in order to examine the knowledge of four groups of primary care physicians with regard to sleep apnea. Sleep apnea is defined as the cessation of breathing for more than 10 seconds in duration and presents as either a total or partial arrest in respiration. Obstruction of the upper airway while respiratory effort persists is termed obstructive sleep apnea. However, if respiratory effort is absent causing airflow to cease for more than 10 seconds, then it is referred to as central sleep apnea. The predominant symptom of sleep apnea is hypersomnolence or excessive daytime sleepiness. 1,2 Polysomnography is the established technique for assessing the presence and severity of sleep-disordered breathing. 3-5 The diagnosis and

Research paper thumbnail of Clinical diagnosis of sleep apnea based on single night of polysomnography vs. two nights of polysomnography

Sleep and Breathing, 2009

The purpose of this study was to investigate apnea-hypopnea index (AHI) across two polysomnograph... more The purpose of this study was to investigate apnea-hypopnea index (AHI) across two polysomnographies (PSGs) to examine AHI variability and impact on clinical diagnosis. Materials and methods Two-night PSGs of 193 sleep clinic patients were reviewed, and the AHI variability was analyzed. Anonymized records from five patients with significant night-tonight AHI variability were used in this study: the two-night PSGs from two patients were represented as four individual PSGs; the two-night PSG for two others were represented as being obtained from two different sleep clinics; the last patient's PSG was shown as a two-night study. Twenty-two sleep experts attending the Associated Professional Sleep Societies meeting were recruited to make diagnoses based on the PSGs. They were told that the PSGs were from seven patients: four with single-night PSG; two with two PSGs, each one from a different clinic; and one patient with a two-night PSG. Results Twenty-one percent of the 193 sleep clinic patients had a nightly PSG AHI variability of greater than 5. Fortyeight percent of all patients had a significantly higher AHI on the first night, and 41% had a significantly higher AHI on the second night. Using an AHI>15 diagnostic criteria, sleep apnea would have been undetected in 20% (n=39) of patients due to low AHI on one night. Furthermore, 13% of all patients had a more severe sleep apnea classification based on the second night of PSG. For the seven cases, 27-36% of sleep experts failed to identify sleep apnea especially when presented with the PSG containing the lower AHI. Incidences of missed sleep apnea diagnoses were reduced to 15-18% when information from two PSGs was presented to the sleep experts. Conclusions Utilizing a large patient population, this study supports the significant night-tonight variability in PSG respiratory variables. Identification of sleep apnea in some patients is reduced when sleep experts are provided with only one PSG recording. The clinical implication is that about 13% of sleep clinic patients might benefit from a second night of PSG.

Research paper thumbnail of Risk of obstructive sleep apnea in open-angle glaucoma versus controls using the STOP-Bang questionnaire

Canadian journal of ophthalmology. Journal canadien d'ophtalmologie, Feb 1, 2018

To compare the percentage of patients at risk for obstructive sleep apnea (OSA) in open-angle gla... more To compare the percentage of patients at risk for obstructive sleep apnea (OSA) in open-angle glaucoma (OAG) versus controls using the STOP-Bang questionnaire. This study used a cross-sectional survey. Patients with OAG and controls completed the STOP-Bang questionnaire-a validated tool to identify patients at high risk for OSA. Patients were considered at risk if they scored 3 or more points or at high risk for moderate/severe OSA if they scored 5 or more out of the maximum 8 points. Demographic information, medical history, and previous diagnosis of OSA were recorded. Details regarding the patients' glaucoma were obtained from their medical records. A total of 437 patients with OAG and 441 controls were included. The mean STOP-Bang score was 3.01 ± 1.3 for the glaucoma group and 3.03 ± 1.4 for the control group (p = 0.92). There was no significant difference between the percentage of subjects considered at risk for OSA (62.7% OAG vs 59.4% controls, p = 0.37) or at high risk fo...

Research paper thumbnail of A comparison of two screening tools for paediatric obstructive sleep apnea

Journal of Sleep Research

Untreated obstructive sleep apnea in children is associated with significant medical and psycholo... more Untreated obstructive sleep apnea in children is associated with significant medical and psychological morbidities. Polysomnographic testing is the gold-standard method for diagnosis of obstructive sleep apnea. However, laboratory-based polysomnography is expensive and associated with a substantial healthcare burden. Thus, a simple valid tool to accurately identify those at high risk of obstructive sleep apnea is essential. We performed a retrospective cross-sectional study of children referred to the Youthdale Child and Adolescent Sleep Clinic. Data were collected from questionnaires and sleep studies reports of 395 children. A comparison between two screening tools for paediatric obstructive sleep apneaa sixitem (parent-response) and an eight-item IF-SLEEPY/IM-SLEEPY scales was performed. The results showed that 42% of the children (n = 164) were diagnosed with obstructive sleep apnea. The six-item scale (score ≥3) exhibited a sensitivity of 17% and a specificity of 95% for diagnosing obstructive sleep apnea. The eight-item IF-SLEEPY scale displayed 82% sensitivity and 28% specificity. The IM-SLEEPY scale exhibited 79% sensitivity and 32% specificity. In children ≥7 years old, the IF-SLEEPY (parent-response) had a sensitivity of 82% and specificity of 28% compared with the child-response (66% and 37%, respectively). Logistic regression analysis revealed that age (odds ratio = 0.78), IF-SLEEPY/IM-SLEEPY score ≥3 (odds ratio = 1.78) and a score ≥2.72 on the six-item scale (odds ratio = 4.54) were predictors of obstructive sleep apnea. This study suggests that the eight-item scale is a better screening tool for paediatric obstructive sleep apnea, with a higher sensitivity and simple yes/no responses that are easy to complete and to score.

Research paper thumbnail of Adrenergic blockade does not restore the canine gastric migrating motor complex during vagal blockade

Research paper thumbnail of CME A Systemic Review of Obstructive Sleep Apnea and Its Implications for Anesthesiologists

Anesthesia and Analgesia, 2008

Research paper thumbnail of Adrenergic blockage does not restore the canine gastric migrating motor complex during vagal blockade

Gastroenterology, Dec 1, 1992

Bilateral cervical cooling blockade of the vagi abolishes the gastric migrating motility complex ... more Bilateral cervical cooling blockade of the vagi abolishes the gastric migrating motility complex (MMC), except for the pylorus. The present study investigated if this finding is caused by adrenergic inhibition of the stomach via sympathetic nerves entering the vagi below the level of the blockade. Stomach and upper small bowel motor activity was monitored in five chronic dogs whose vagosympathetic nerve trunks were previously isolated in bilateral, cervical skin loops to permit blockade by cooling. Adrenergic blockade was performed by an initial bolus injection of phentolamine (0.3 mg/kg) and propranolol (0.3 mg/kg) followed by a continuous intravenous infusion of the combined drugs at a rate of 1.5 mg.kg-1.h-1 for phentolamine and 0.3 mg.kg-1.h-1 for propranolol. Bilateral cervical vagal blockade abolished the gastric MMC, with persistence of phase III of the MMC in the upper small bowel. During combined vagal and adrenergic blockade, gastric contractions were absent in 4 of the 22 duodenal complexes observed. In the other duodenal complexes, intermittent gastric contractions were associated with all phases of the intestinal MMC, including phase I. At times, this contractile activity was accentuated during phase III but never reached the intensity of activity or showed the typical coordination features of the gastric MMC seen with the vagi intact. Therefore, unopposed adrenergic inhibition of the stomach does not explain the absence of the gastric MMC during vagal cooling blockade. Under normal circumstances, the vagus nerve is the most important pathway for central control of the appearance of the gastric MMC.

Research paper thumbnail of The Vagus, Motilin, and the Migrating Motor Complex. Author's Reply

Research paper thumbnail of Moderate Exercise and Bright Light Treatment in Overweight and Obese Individuals*

Obesity, 2007

Increased physical activity is important given the concern over the growing rates of obesity. The... more Increased physical activity is important given the concern over the growing rates of obesity. The aim of this study is to conduct a controlled investigation of the effects of bright light therapy and exercise on weight loss and body composition in overweight and obese individuals. Twenty-five overweight and obese subjects were assigned to 6 weeks of moderate exercise with or without bright light treatment. Outcome measure included changes in body mass and body composition and ratings of mood, seasonality, and sleep. Body weight decreased significantly with exercise in subjects in the light and non-light treatment groups, but the change was not significantly different between the groups. Similar results were found for BMI. With exercise, body fat decreased significantly only in the light treatment group. There was a significant effect of the interaction of group by time on body fat composition, but the group by time interaction failed to reach statistical significance for body weight and BMI. Mood scores improved significantly with exercise in the light group, but no significant changes were noted regarding sleep. This preliminary study is the first to show that addition of bright light treatment to a 6-week moderate exercise program can alter body composition by significantly reducing body fat. The reduction in body fat mass is of particular importance, because visceral fat has been particularly implicated as a major factor in the development of the metabolic syndrome. This study is an important step toward finding ways to maximize the effects of exercise.

Research paper thumbnail of The Toronto Hospital Alertness Test scale: relationship to daytime sleepiness, fatigue, and symptoms of depression and anxiety

Nature and Science of Sleep, 2016

Treatment centres, 3 Youthdale child and adolescent Sleep centre,

Research paper thumbnail of Three Siblings with Prader-Willi Syndrome: Brief Review of Sleep and Prader-Willi Syndrome

Case Reports in Neurological Medicine, 2015

Prader-Willi syndrome (PWS) is a genetic disorder characterized by short stature, mental retardat... more Prader-Willi syndrome (PWS) is a genetic disorder characterized by short stature, mental retardation, hypotonia, functionally deficient gonads, and uncontrolled appetite leading to extreme obesity at an early age. Patients with this condition require multidisciplinary medical care, which facilitates a significant improvement in quality of life. PWS is the first human disorder to be attributed to genomic imprinting. Prevalence varies in the literature, ranging from 1 in 8,000 in the Swedish population to 1 in 54,000 in the United Kingdom. Rarely, the genetic mechanism responsible for Prader-Willi syndrome can be inherited. We report a highly unique case of three siblings who share this condition. This report describes a case of two brothers and one half sister with PWS. All three siblings have sleep-related complaints. The sister died at the age of 24 years in her sleep, with the cause of death reported as obstructive sleep apnea. The outcome was positive in both of the brothers’ cas...

Research paper thumbnail of Weighing the balance: how analgesics used in chronic pain influence sleep?

British journal of pain, 2014

Pain and sleep share a bidirectional relationship, with each influencing the other. Several excel... more Pain and sleep share a bidirectional relationship, with each influencing the other. Several excellent reviews have explored this relationship. In this article, we revisit the evidence and explore existing research on this complex inter-relationship. The primary focus of the article is on the pharmacological treatment of chronic non-malignant pain and the main purpose is to review the effect of various pharmacological agents used in the management of chronic pain on sleep. This has not been comprehensively done before. We explore the clinical use of these agents, their impact on sleep architecture and sleep physiology, the mechanism of action on sleep parameters and sleep disorders associated with these agents. Pharmacological classes reviewed include antidepressants, opioid analgesics, anti-epileptics, cannabinoids and non-steroidal anti-inflammatory agents, drugs most commonly used to manage chronic pain. The objective is to help health professionals gain better insight into the co...

Research paper thumbnail of How, what, and why of sleep apnea. Perspectives for primary care physicians

Canadian family physician Médecin de famille canadien, 2002

To review the need for primary care physicians to screen for patients with obstructive sleep apne... more To review the need for primary care physicians to screen for patients with obstructive sleep apnea (OSA). Literature was reviewed via MEDLINE from 1993 to 2000, inclusive, using the search term "sleep apnea" combined with "epidemiology," "outcome," and "diagnosis and treatment." Citations in this review favour more recent, well controlled and randomized studies, but findings of pilot studies are included where other research is unavailable. Obstructive sleep apnea is a disorder with serious medical, socioeconomic, and psychological morbidity, yet most patients with OSA remain undetected. Primary care physicians have a vital role in screening for these patients because diagnosis can be made only through overnight (polysomnographic) studies at sleep clinics. Physicians should consider symptoms of excessive or loud snoring, complaints of daytime sleepiness or fatigue, complaints of unrefreshing sleep, and an excess of weight or body fat distribut...

Research paper thumbnail of Home-use servo-ventilation therapy in chronic pain patients with central sleep apnea: initial and 3-month follow-up

Sleep and Breathing, 2015

Purpose Opioid treatment of non-malignant chronic pain can result in hypoxemia, hypercarbia, and ... more Purpose Opioid treatment of non-malignant chronic pain can result in hypoxemia, hypercarbia, and central sleep apnea. The aim of this study was to determine the initial efficacy of auto servo-ventilation (ASV) and after 3 months of home use. Methods This prospective multicenter interventional study recruited chronic pain patients prescribed ≥100 morphine equivalents for at least 4 months. Participants Following full-night polysomnography (PSG) to confirm the presence of sleep-disordered breathing, patients were randomized to three additional full-night-attended PSGs with continuous positive airway pressure (CPAP), ASV, and servo-ventilation with an initial mandatory pressure support of 6 cm H 2 O (ASV manual PSmin 6). Following the PSGs, patients were sent home with EncoreAnywhere and ASV with or without mandatory pressure support. Results Based on the initial PSG studies, CPAP improved but did not normalize the apnea-hypopnea index (AHI), central apnea index (CAI), or hypopnea index (HI), as all remained elevated. Clinically significant reductions were noted after just one night of ASVand ASV manual (PSmin 6). After 3 months of ASV home use, the AHI, CAI, and obstructive apnea index (OAI) were significantly reduced when compared to baseline diagnostic levels and even when compared to respiratory disturbance indices with CPAP treatment. Conclusions Initial and home use of ASV for 3 months resulted in significantly lower AHI, CAI, and OAI. This reduction attests to the efficacy of ASV treatment in chronic pain patients on high doses of opioids.

Research paper thumbnail of Sleep apnea, hypertension, and the effects of continuous positive airway pressure

American journal of hypertension, 2005

Sleep apnea is being studied as a risk factor for hypertension. This observational chart review w... more Sleep apnea is being studied as a risk factor for hypertension. This observational chart review was conducted to determine the long-term effects of continuous positive airway pressure (CPAP) treatment on blood pressure (BP) in a sample of sleep apnea patients from urban and rural populations. This study was conducted using data from 180 clinical charts from 1995 to 2002. Patients were identified as hypertensive or normotensive by their initial BP values before they were diagnosed with sleep apnea and were also reviewed after the use of CPAP. Of the patients diagnosed with sleep apnea, 32% were found to have hypertension (mean systolic BP: 164.4 +/- 20.3 mmHg; mean diastolic BP: 96.9 +/- 5.3 mmHg). The average use of CPAP was 12.1 +/- 22.4 months. The hypertensive group showed a significant reduction in BP with CPAP use: systolic BP dropped by an average of 11.2 mmHg (P < .001) and diastolic BP dropped by an average of 5.9 mmHg (P < .001). Our results confirm that frequency of ...

Research paper thumbnail of Small intestinal motility in fasted and postprandial states: effect of transient vagosympathetic blockade

The American journal of physiology, 1987

We investigated vagal control of the migrating myoelectric complex (MMC) and postprandial pattern... more We investigated vagal control of the migrating myoelectric complex (MMC) and postprandial pattern of the canine small intestine. Gastric and small intestinal motility were monitored in six conscious dogs. The vagosympathetic nerves, previously isolated in bilateral skin loops, were blocked by cooling. To feed, a meat-based liquid food was infused by tube into the gastric fundus. MMC phases I, II, III, and IV were observed in the fasted state. On feeding, the fed pattern appeared quickly in the proximal small bowel but was delayed distally. Vagal blockade abolished all gastric contractions and spiking activity as well as the small bowel fed pattern. During vagal blockade, the small bowel exhibited MMC-like migrating bursts of spikes in both the fasted and fed states. The migration and cycling of these bursts were not significantly different from the MMC, but the duodenal and jejunal phase II was absent or shortened. On termination of vagal blockade, normal fasting or fed activity rea...

Research paper thumbnail of Polysomnographic and symptomatological analyses of major depressive disorder patients treated with mirtazapine

Canadian journal of psychiatry. Revue canadienne de psychiatrie, 2006

This study aimed to characterize the effects of mirtazapine on polysomnographic sleep, especially... more This study aimed to characterize the effects of mirtazapine on polysomnographic sleep, especially slow wave sleep (SWS) and rapid eye movement (REM) sleep, as well as its effects on clinical symptoms in patients with major depressive disorder (MDD). Sixteen MDD patients were treated with mirtazapine 30 mg taken 30 minutes before bedtime. Polysomnographic and subjective sleep, as well as other clinical data, were collected at baseline and on Days or Nights 2, 9, 16, 30, and 58 during treatment. We used repeated measures analysis of variance, including pairwise comparison, to analyze data statistically. Mirtazapine administration increased total SWS and the SWS in the first sleep cycle, but not SWS in the second sleep cycle. The medication increased REM latency and the duration of the first REM episode; it also decreased the number of REM episodes. Simultaneously, mirtazapine significantly reduced wake-after-sleep onset and scores on the Athens Insomnia Scale. After patients took the ...

Research paper thumbnail of Validation of a short questionnaire in English and French for use in patients with persistent upper gastrointestinal symptoms despite proton pump inhibitor therapy: the PASS (Proton pump inhibitor Acid Suppression Symptom) test

Canadian journal of gastroenterology = Journal canadien de gastroenterologie, 2005

The management of persistent symptoms during acid suppression therapy in patients with gastroesop... more The management of persistent symptoms during acid suppression therapy in patients with gastroesophageal reflux disease or dyspepsia might be improved if patient-physician communication regarding the presence and character of these persistent symptoms were facilitated. To validate a short, simple questionnaire (the Proton pump inhibitor [PPI] Acid Suppression Symptom [PASS] test), in English and French, to identify patients with persistent acid-related symptoms during PPI therapy and document their response to a change in therapy. Patients with persistent acid-related symptoms on PPI therapy were interviewed to produce a draft, five-item questionnaire; content validity was evaluated by focus groups comprising English- and French-speaking patients. Psychometric validity was subsequently evaluated in a multicentre, family practice-based study of English- and French-speaking patients with persistent acid-related upper gastrointestinal symptoms despite PPI therapy. The PASS test, Global ...

Research paper thumbnail of Validation of a pediatric obstructive sleep apnea screening tool

International Journal of Pediatric Otorhinolaryngology, 2013

Pediatric obstructive sleep apnea (OSA) is a prevalent but under-diagnosed disease. The importanc... more Pediatric obstructive sleep apnea (OSA) is a prevalent but under-diagnosed disease. The importance of screening for OSA in every child has been recently re-emphasized by the American Academy of Pediatrics Guidelines. Although several screening questionnaires are available for pediatric OSA, they are either complicated to use or not sensitive enough, and therefore OSA is seldom screened in primary care settings. Here, we validated a previously developed short (6-item) hierarchically-based screening questionnaire tool for pediatric OSA. Parents of 85 children referred for a sleep study at a pediatric community-based sleep clinic completed the questionnaire and their children underwent an overnight PSG. Receiver operator curve analyses and other predictive scales were assessed. The 6-item questionnaire exhibited favorable sensitivity and fair specificity for diagnosis of OSA, which varied depending on the apnea-hypopnea index used for OSA definition. A 6-item questionnaire is a sensitive and easy-to-use screening tool for pediatric OSA in a pediatric sleep clinic setting.

Research paper thumbnail of I’M SLEEPY: A short pediatric sleep apnea questionnaire

International Journal of Pediatric Otorhinolaryngology, 2014

Pediatric obstructive sleep apnea (OSA) is a prevalent but under-diagnosed disease. The importanc... more Pediatric obstructive sleep apnea (OSA) is a prevalent but under-diagnosed disease. The importance of screening for OSA has been emphasized in the recently published guidelines for the diagnosis and management of childhood OSA. Several pediatric OSA questionnaires are available, but are complicated to use or not sensitive enough for screening. In this study we developed an 8-item (IF SLEEPY) screening tool for pediatric OSA. One hundred and fifty children referred for evaluation at a pediatric sleep clinic and their parents completed the questionnaire and had a polysomnography. Two further questionnaires were developed: I SLEEPY and I&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;M SLEEPY versions. The questionnaires&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; scores were compared to the apnea hypopnea index (AHI) and the validity of each questionnaire was evaluated. The I&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;M SLEEPY version was found to have the highest sensitivity (82%) and a modest specificity (50%) for OSA diagnosis. I&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;M SLEEPY is a sensitive and easy-to-use screening tool for pediatric OSA. It is intended to be used by the primary physician in every suspected case of OSA. Larger studies are needed in the primary care setting for the validation of this tool.

Research paper thumbnail of Knowledge of Sleep Apnea in a Sample Grouping of Primary Care Physicians

Sleep And Breathing, 2001

This pilot study was performed in order to examine the knowledge of four groups of primary care p... more This pilot study was performed in order to examine the knowledge of four groups of primary care physicians with regard to sleep apnea. Sleep apnea is defined as the cessation of breathing for more than 10 seconds in duration and presents as either a total or partial arrest in respiration. Obstruction of the upper airway while respiratory effort persists is termed obstructive sleep apnea. However, if respiratory effort is absent causing airflow to cease for more than 10 seconds, then it is referred to as central sleep apnea. The predominant symptom of sleep apnea is hypersomnolence or excessive daytime sleepiness. 1,2 Polysomnography is the established technique for assessing the presence and severity of sleep-disordered breathing. 3-5 The diagnosis and

Research paper thumbnail of Clinical diagnosis of sleep apnea based on single night of polysomnography vs. two nights of polysomnography

Sleep and Breathing, 2009

The purpose of this study was to investigate apnea-hypopnea index (AHI) across two polysomnograph... more The purpose of this study was to investigate apnea-hypopnea index (AHI) across two polysomnographies (PSGs) to examine AHI variability and impact on clinical diagnosis. Materials and methods Two-night PSGs of 193 sleep clinic patients were reviewed, and the AHI variability was analyzed. Anonymized records from five patients with significant night-tonight AHI variability were used in this study: the two-night PSGs from two patients were represented as four individual PSGs; the two-night PSG for two others were represented as being obtained from two different sleep clinics; the last patient's PSG was shown as a two-night study. Twenty-two sleep experts attending the Associated Professional Sleep Societies meeting were recruited to make diagnoses based on the PSGs. They were told that the PSGs were from seven patients: four with single-night PSG; two with two PSGs, each one from a different clinic; and one patient with a two-night PSG. Results Twenty-one percent of the 193 sleep clinic patients had a nightly PSG AHI variability of greater than 5. Fortyeight percent of all patients had a significantly higher AHI on the first night, and 41% had a significantly higher AHI on the second night. Using an AHI>15 diagnostic criteria, sleep apnea would have been undetected in 20% (n=39) of patients due to low AHI on one night. Furthermore, 13% of all patients had a more severe sleep apnea classification based on the second night of PSG. For the seven cases, 27-36% of sleep experts failed to identify sleep apnea especially when presented with the PSG containing the lower AHI. Incidences of missed sleep apnea diagnoses were reduced to 15-18% when information from two PSGs was presented to the sleep experts. Conclusions Utilizing a large patient population, this study supports the significant night-tonight variability in PSG respiratory variables. Identification of sleep apnea in some patients is reduced when sleep experts are provided with only one PSG recording. The clinical implication is that about 13% of sleep clinic patients might benefit from a second night of PSG.