PubMed Health⌕ Search

Biomedical subjects

Stuart F Quan

Publications and source records attributed to Stuart F Quan.

At least 37 records · Page 2Linked to original sources
PubMed2004

Ventilatory drive and the apnea-hypopnea index in six-to-twelve year old children.

BACKGROUND: We tested the hypothesis that ventilatory drive in hypoxia and hypercapnia is inversely correlated with the number of hypopneas and obstructive apneas per hour of sleep (obstructive apnea hypopnea index, OAHI) in children. METHODS: Fifty children, 6 to 12 years of age were studied. Participants had an in-home unattended polysomnogram to compute the OAHI. We subsequently estimated ventilatory drive in normoxia, at two levels of isocapnic hypoxia, and at three levels of hyperoxic hypercapnia in each subject. Experiments were done during wakefulness, and the mouth occlusion pressure measured 0.1 seconds after inspiratory onset (P0.1) was measured in all conditions. The slope of the relation between P0.1 and the partial pressure of end-tidal O2 or CO2 (PETO2 and PETCO2) served as the index of hypoxic or hypercapnic ventilatory drive. RESULTS: Hypoxic ventilatory drive correlated inversely with OAHI (r = -0.31, P = 0.041), but the hypercapnic ventilatory drive did not (r = -0.19, P = 0.27). We also found that the resting PETCO2 was significantly and positively correlated with the OAHI, suggesting that high OAHI values were associated with resting CO2 retention. CONCLUSIONS: In awake children the OAHI correlates inversely with the hypoxic ventilatory drive and positively with the resting PETCO2. Whether or not diminished hypoxic drive or resting CO2 retention while awake can explain the severity of sleep-disordered breathing in this population is uncertain, but a reduced hypoxic ventilatory drive and resting CO2 retention are associated with sleep-disordered breathing in 6-12 year old children.

Journal Article↗
PubMed2004

Parasomnias and sleep disordered breathing in Caucasian and Hispanic children - the Tucson children's assessment of sleep apnea study.

BACKGROUND: Recent studies in children have demonstrated that frequent occurrence of parasomnias is related to increased sleep disruption, mental disorders, physical harm, sleep disordered breathing, and parental duress. Although there have been several cross-sectional and clinical studies of parasomnias in children, there have been no large, population-based studies using full polysomnography to examine the association between parasomnias and sleep disordered breathing. The Tucson Children's Assessment of Sleep Apnea study is a community-based cohort study designed to investigate the prevalence and correlates of objectively measured sleep disordered breathing (SDB) in pre-adolescent children six to 11 years of age. This paper characterizes the relationships between parasomnias and SDB with its associated symptoms in these children. METHODS: Parents completed questionnaires pertaining to their child's sleep habits. Children had various physiological measurements completed and then were connected to the Compumedics PS-2 sleep recording system for full, unattended polysomnography in the home. A total of 480 unattended home polysomnograms were completed on a sample that was 50% female, 42.3% Hispanic, and 52.9% between the ages of six and eight years. RESULTS: Children with a Respiratory Disturbance Index of one or greater were more likely to have sleep walking (7.0% versus 2.5%, p < 0.02), sleep talking (18.3% versus 9.0%, p < 0.006), and enuresis (11.3% versus 6.3%, p < 0.08) than children with an Respiratory Disturbance Index of less than one. A higher prevalence of other sleep disturbances as well as learning problems was observed in children with parasomnia. Those with parasomnias associated with arousal were observed to have increased number of stage shifts. Small alterations in sleep architecture were found in those with enuresis. CONCLUSIONS: In this population-based cohort study, pre-adolescent school-aged children with SDB experienced more parasomnias than those without SDB. Parasomnias were associated with a higher prevalence of other sleep disturbances and learning problems. Clinical evaluation of children with parasomnias should include consideration of SDB.

Arizona↗
PubMed2004

The effects of age, sex, ethnicity, and sleep-disordered breathing on sleep architecture.

BACKGROUND: Polysomnography is used to assess sleep quality and to gauge the functional effect of sleep disorders. Few population-based data are available to estimate the variation in sleep architecture across the population and the extent to which sleep-disordered breathing (SDB), a common health condition, contributes to poor sleep independent of other factors. The objective of this study was to describe the population variability in sleep quality and to quantify the independent associations with SDB. METHODS: Cross-sectional analyses were performed on data from 2685 participants, aged 37 to 92 years, in a community-based multicenter cohort study. Dependent measures included the percentage time in each sleep stage, the arousal index, and sleep efficiency. Independent measures were age, sex, ethnicity, comorbidity status, and the respiratory disturbance index. RESULTS: Lighter sleep was found in men relative to women and in American Indians and blacks relative to other ethnic groups. Increasing age was associated with impaired sleep in men, with less consistent associations in women. Notably, women had, on average, 106% more slow wave sleep. Sleep-disordered breathing was associated with poorer sleep; however, these associations were generally smaller than associations with sex, ethnicity, and age. Current smokers had lighter sleep than ex-smokers or never smokers. Obesity had little effect on sleep. CONCLUSIONS: Sleep architecture varies with sex, age, ethnicity, and SDB. Individual assessment of the effect of SDB on sleep quality needs to account for other host characteristics. Men, but not women, show evidence of poorer sleep with aging, suggesting important sex differences in sleep physiology.

Adult↗
PubMed2004

Associations between chemical odor intolerance and sleep disturbances in community-living adults.

OBJECTIVE: To investigate associations between sleep disturbances and chemical odor intolerance (COI), which is the subjective report of feeling ill from common odors, such as carpet glue or pesticides. METHODS: This cross-sectional study consisted of government employees and their family members (n=140; 61% women, mean age=46.3 years) derived from a stratified cluster population living in Pima County, Tucson, AZ. Subjects completed a standard survey that included sleep symptoms, a validated measure of COI, and two questions regarding anxiety and depression. Odds ratios (OR) with 95% confidence intervals (CI) were computed to test the association between COI and sleep symptoms. Stratification according to the Mantel-Haenszel method and logistic regression models were used to test for confounding and/or effect modification. RESULTS: After adjusting for age and gender, subjects with COI were significantly more likely to report difficulty staying asleep (OR=3.06; CI=1.17-8.03), insufficient sleep (OR=3.93; CI=1.43-10.79), and nightmares (OR=3.17; CI=1.14-8.81) compared to persons without COI. Associations between COI, sleep maintenance problems and insufficient sleep were still significant after adjusting for gender and depression; however, the association between COI and nightmares became borderline. CONCLUSIONS: Compared to the non-COI, persons with COI are more likely to report sleep maintenance insomnia and insufficient sleep independent of self-reported depression. Nightmares appear to be related more to depression than to COI.

Adhesives↗
PubMed2004

Is there a relationship between obstructive sleep apnea and gastroesophageal reflux disease?

BACKGROUND AND AIMS: The causative relationship between obstructive sleep apnea (OSA) and gastroesophageal reflux disease (GERD) remains an area of controversy. The aim of the study is to further explore the relationship between OSA and GERD in a large group of patients with OSA. METHODS: One hundred thirty-six patients referred for polysomnographic studies at the University of Arizona Sleep Center were included in this study. All patients were assessed by means of a demographic survey, the validated GERD Symptom Checklist, and the Sleep Heart Health Study Sleep Habits Questionnaire. Polysomnograms were scored for objective measures of sleep and breathing. OSA is defined as an apnea-hypopnea index > 5 with compatible symptoms. RESULTS: Of the 136 subjects, 101 (74%) were found to have OSA. Self-report of heartburn or acid regurgitation symptoms was unrelated to severity of sleep apnea. Additionally, OSA was not influenced by the severity of GERD. Objective measures of disordered sleep had stronger associations with age, smoking, and alcohol use than GERD in men and stronger associations with age and body mass index than GERD in women. Subjectively reported sleep quality was affected more strongly by GERD severity than by age, smoking, alcohol use, or the presence of OSA. Only females administered antireflux medications were less likely to report poor sleep quality. CONCLUSIONS: Subjective reports of sleep quality were affected by GERD severity, but an objective correlation between OSA and GERD was lacking. This may suggest that GERD and OSA are common entities that share similar risk factors, but appear not to be causally linked.

Adult↗
PubMed2004

Evaluating the effects of medical disorders on sleep in the older patient.

Older adults often experience sleep disturbances, but most fall to mention these sleep problems to their physicians out of a false belief that sleep troubles are just a consequence of getting older. On the contrary, sleep complaints in older adults are often the result of medical or psychiatric illnesses that can be managed, resulting in a return to restful sleep. It is important for physicians and patients to communicate about sleep disturbances, and for physicians to ask appropriate questions targeted at identifying the underlying cause of the sleep problem, particularly in patients with chronic medical conditions.

Aged↗
PubMed2003

Clinical outcomes associated with sleep-disordered breathing in Caucasian and Hispanic children--the Tucson Children's Assessment of Sleep Apnea study (TuCASA).

STUDY OBJECTIVES: This report describes clinical outcomes and threshold levels of respiratory disturbance index (RDI) associated with sleep-disordered breathing in children participating in the Tucson Children's Assessment of Sleep Apnea study. DESIGN: A community-based, prospective cohort study designed to assess the severity of sleep-related symptoms associated with sleep-disordered breathing in children aged 6 to 11 years. SETTING: Students attending elementary school in the Tucson Unified School District. PARTICIPANTS: Unattended home polysomnograms were completed on 239 children-55.2% boys, 51% Hispanic, and 55% between the ages of 6 and 8 years. MEASUREMENTS AND RESULTS: Based on full home polysomnography, levels of RDI that correspond to a higher prevalence of clinical symptoms of sleep-disordered breathing in children aged 6 to 11 were observed. An RDI of at least 5 was associated with frequent snoring (20.3% vs 9.1%, P<.01), excessive daytime sleepiness (22.9% vs 10.7%, P<.01), and learning problems (8.5% vs 2.5%, P<.04) when no oxygen desaturation accompanied the respiratory event. An RDI of at least 1 was associated with these symptoms when a 3% oxygen desaturation was required, snoring (24.0% vs 10.4%, P<.006), excessive daytime sleepiness (24.0% vs 13.4%, P<.04), and learning problems (10.7% vs 3.0%, P<.02). Hispanic or Caucasian ethnicity, sex, age category, obesity, insomnia, and witnessed apnea were not associated with RDI regardless of event definition. CONCLUSIONS: The Tucson Children's Assessment of Sleep Apnea study has shown that there are values of RDI based on polysomnography that correspond to an increased rate of clinical symptoms in children ages 6 to 11 years.

Body Mass Index↗
PubMed2003

Blood pressure elevation associated with sleep-related breathing disorder in a community sample of white and Hispanic children: the Tucson Children's Assessment of Sleep Apnea study.

BACKGROUND: The Tucson Children's Assessment of Sleep Apnea study (TuCASA) was designed to investigate the prevalence and correlates of objectively measured sleep-related breathing disorder (SBD) in preadolescent Hispanic and white children. OBJECTIVE: To describe the associations of SBD and elevation in resting blood pressure in the first 239 children enrolled in TuCASA. DESIGN: Children between the ages of 6 and 11 years (45% girls and 51% Hispanic) from elementary schools of the Tucson Unified School District were enrolled in this prospective cohort study. Resting systolic and diastolic blood pressure, sleep symptoms, and parental smoking status were obtained during evening home visits, followed by overnight unattended home polysomnography. RESULTS: The mean (SD) systolic and diastolic blood pressures were 98.4 (10.6) mm Hg and 62.0 (8.9) mm Hg, respectively. Fifteen children had hypertension. The mean (SD) respiratory disturbance index (2%), defined as the number of apneas and hypopneas per hour of sleep associated with a 2% oxygen desaturation, was 2.3 (3.8) events per hour. Factors independently associated with systolic and diastolic blood pressure elevation were obesity, sleep efficiency, and respiratory disturbance index (2%). CONCLUSIONS: In preadolescent children, elevated blood pressure is associated with SBD and obesity, as previously noted in adults. The control of obesity in childhood may be important to reduce the daytime consequences of SBD and to reduce the risks of life-long hypertension.

Arizona↗
PubMed2003

Serum pneumoproteins: a cross-sectional comparison of firefighters and police.

BACKGROUND: Serum pneumoproteins provide a measure of the permeability of the lower respiratory tract, and have shown promise as a biomarker of acute and chronic exposure to respiratory toxicants. METHODS: To evaluate the effects of chronic occupational smoke exposure, 105 firefighters were compared with 44 police controls in a cross-sectional study using spirometry, diffusing capacity of the lung, serum Clara cell protein (CC16), and serum surfactant-associated protein A (SP-A) measurements. RESULTS: There were no significant differences in age, gender, height, spirometry (FVC and FEV(1)), and diffusing capacity between the two groups. Serum SP-A was lower in firefighters (260.1 +/- 121.2 microg/L) than police (316.0 +/- 151.4 microg/L, P = 0.019). Serum CC16 was also lower in firefighters (8.39 +/- 3.11 microg/L) than police (10.56 +/- 4.20 microg/L, P < 0.001), although this difference lost statistical significance when adjusted for confounders. CONCLUSIONS: Firefighters have lower serum concentrations of SP-A than do police. Although the clinical significance of this finding is presently unknown, SP-A deserves further study as a biomarker of toxic exposure to the lower respiratory tract.

Adult↗
PubMed2003

Recruitment of healthy adults into a study of overnight sleep monitoring in the home: experience of the Sleep Heart Health Study.

The Sleep Heart Health Study (SHHS) is a prospective cohort study using participants from several ongoing cardiovascular and respiratory disease research projects to investigate the relationship between sleep-disordered breathing and cardiovascular disease. This study design required unusual and different recruiting techniques to meet the study's enrollment goal of between 6000 and 6600 participants. Individuals were recruited to undergo an overnight home polysomnogram, completion of several questionnaires, and collection of a small amount of physical examination data. This article describes the methods used to recruit these participants and how these procedures influenced the final participation rate and the representativeness of SHHS to its parent cohorts. Of 30,773 people eligible for recruitment into SHHS, attempts were made to enroll 11,145 (36%). Of those contacted, 6441 ultimately agreed to participate (58%). Recruitment rates (38 to 91%) varied among sites. SHHS participants were slightly younger (63.0 vs. 65.0 years, p < 0.001), had more years of education (14.1 vs. 13.7, p < 0.001), more likely to snore (34% vs. 23%, p < 0.001), had higher Epworth sleepiness scores (7.7 vs. 6.5, p < 0.001), slightly higher higher systolic and diastolic blood pressures (127.6/73.9 vs. 127.2/72.1, p < 0.001 for diastolic only), and a slightly higher body mass index (BMI) (28.5 vs. 27.5, p < 0.001). We conclude that it is feasible to recruit existing participants from one large-scale epidemiologic study into another with a high degree of success. However, the characteristics of the new cohort may vary in several respects from their original cohorts and therefore interpretation of study results will have to consider these differences.

Adult↗
PubMed2003

Sleep architecture in normal Caucasian and Hispanic children aged 6-11 years recorded during unattended home polysomnography: experience from the Tucson Children's Assessment of Sleep Apnea Study (TuCASA).

OBJECTIVE: To obtain normative sleep architecture data from unattended home polysomnography in Caucasian and Hispanic children aged 6-11 years. DESIGN AND SUBJECTS: Unattended home polysomnography was performed on a single night in Caucasian and Hispanic children aged 6-11 years as part of the Tucson Children's Assessment of Sleep Apnea Study (TuCASA), a cohort study designed to examine the prevalence and correlates of sleep disordered breathing. A subset of 42 children enrolled in TuCASA who had no symptoms of any sleep disorder and had polysomnograms without technical recording problems. RESULTS: Sleep architecture in preadolescent Caucasian and Hispanic children was not different between boys and girls. However, total sleep time (TST), sleep efficiency (SLE) and time spent in REM sleep declined with increasing age. In addition, the number of sleep to wake stage shifts was slightly higher in younger children. Hispanic children had less Stage 3/4 sleep (18+/-1 vs. 22+/-1%, P</=0.02) and correspondingly more Stage 2 sleep (55+/-2 vs. 50.0+/-1%, P</=0.02) than their Caucasian counterparts. CONCLUSIONS: Using unattended home polysomnography, indices of sleep duration and architecture are not different between preadolescent boys and girls. However, with increasing age, TST and SLE decreased. In addition, there are differences in sleep architecture between Caucasians and Hispanics, which may be an important consideration in the evaluation of children with sleep disorders.

Child↗
PubMed2003

Learning in children and sleep disordered breathing: findings of the Tucson Children's Assessment of Sleep Apnea (tuCASA) prospective cohort study.

We examined the relationship between nocturnal respiratory disturbance and learning and compared learning in children with and without nocturnal respiratory disturbance. Subjects were 149 participants in a prospective cohort study examining sleep in children ages 6-12: The Tucson Children's Assessment of Sleep Apnea study (TuCASA). Sleep was assessed via home polysomnography. Intelligence, learning and memory, and academic achievement were assessed. Parents rated attention. Group comparisons were used to test the hypothesis that the group with an apnea/hypopnea index (AHI) of 5 or more (n = 77) would have weaker performance than the group with AHI less than 5 (n = 72). The group with AHI of 5 or more had weaker learning and memory though differences between groups decreased when arousals were taken into account. There was a greater percentage of Stage 1 sleep in the AHI 5 or more group, and Stage 1 percentage was negatively related to learning and memory in the sample (n = 149). There were negative relationships between AHI and immediate recall, Full Scale IQ, Performance IQ, and math achievement. Hypoxemia was associated with lower Performance IQ. Thus, findings suggest that nocturnal respiratory disturbance is associated with decreased learning in otherwise healthy children, that sleep fragmentation adversely impacts learning and memory, and that hypoxemia adversely influences nonverbal skills.

Attention↗
PubMed2003

Symptoms related to sleep-disordered breathing in white and Hispanic children: the Tucson Children's Assessment of Sleep Apnea Study.

STUDY OBJECTIVES: The Tucson Children's Assessment of Sleep Apnea (TuCASA) study is designed to investigate the prevalence and correlates of objectively measured sleep-disordered breathing (SDB) in preadolescent children. This article describes the parental report of sleep symptoms associated with SDB in Hispanic and white children. DESIGN: A 13-question sleep habits screening questionnaire designed to assess the severity of sleep-related symptoms associated with SDB in children 4 to 11 years of age. SETTING: Questionnaires were completed by the parents of children attending elementary school in the Tucson Unified School District, Tucson, AZ. PARTICIPANTS: There were 1,494 questionnaires returned, which comprised a sample of whites (38%), Hispanics (45%), and other races (17%). Of these questionnaires, 1,214 were returned for the children of white (45.8%; 556 children) or Hispanic (54.2%; 658 children) ethnicity only. The primary analysis was completed on these 613 boys (50.5%) and 601 girls (49.5%). RESULTS: In the total sample of 1,494 children, parents were more likely to report excessive daytime sleepiness (EDS) in female children than in male children (p <.01), however, this association did not achieve significance in the sample of only white and Hispanic children (p <.07). Composite variables for EDS and witnessed apnea (WITAP) show that parents of Hispanic children were more likely to report EDS (p <.01) and WITAP (p <.007). Hispanic children were also more likely to have learning problems (LPs) [p <.03] and to snore frequently (SN) [p <.02] than were white children. There were no significant differences between boys and girls for SN or WITAP. Hispanic boys were more likely to have reports of EDS (p <.02) and LPs (p <.04) than white boys, however, there were no other significant differences in gender or ethnicity in reports of EDS or LPs for white or Hispanic boys and girls. Those children with frequent LPs were significantly more likely to have SN (p <.001), EDS (p <.001), and WITAP (p <.001). A logistic regression model predicting LP resulted in significant adjusted odds ratios (ORs) of 2.4 for SN, 2.5 for EDS, and 2.1 for children aged 8 to 11 years. A similar model for EDS resulted in significant adjusted ORs of 3.2 for SN, 5.7 for WITAP, and 1.6 for female gender. Ethnicity was not significant in either model. CONCLUSIONS: Hispanic children in the population-based TuCASA study experienced more frequent symptoms associated with SDB, such as SN, EDS, WITAP, and LPs, than did white children. Children with LPs are 2.4 times more likely to have SN, 2.5 times more likely to have EDS, and were 2.1 times more likely to be between the ages of 8 and 11 years. Children with EDS were 3.2 times more likely to have SN, 5.7 times more likely to have WITAP, and were 1.6 times more likely to be a girl.

Arizona↗
PubMed2002

Sleep disordered breathing.

Cause and effect relationships between sleep disordered breathing (SDB) and illness, poorer quality of life, and public health have been largely overlooked and undertreated by healthcare providers. Obstructive sleep apnea (OSA), central sleep apnea, upper airway resistance syndrome, and obesity hypoventilation are the primary syndromes that fall under the rubric of SDB. Each of these syndromes is defined; however, OSA is the most common form of SDB, and is the focus of this article. Epidemiology, pathophysiology, behavioral manifestations, cardiovascular comorbidity, clinical evaluation, and treatment for OSA are the main topics covered. The article concludes with the role of the nurse in SDB.

Cardiovascular Diseases↗