Richard J. Schwab

William Penn University, Filadelfia, Pennsylvania, United States

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Publications (120)464.16 Total impact

  • Richard J Schwab · Carole L Marcus

    No preview · Article · Oct 2015 · American Journal of Respiratory and Critical Care Medicine
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    Preview · Article · Sep 2015 · Journal of Cerebral Blood Flow & Metabolism
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    ABSTRACT: Structural risk factors for obstructive sleep apnea syndrome (OSAS) in adolescents have not been well characterized. Since many adolescents with OSAS are obese, we hypothesized that the anatomic OSAS risk factors would be more similar to those in adults than children. To investigate the anatomic risk factors in adolescents with OSAS compared to obese and lean controls, using magnetic resonance imaging (MRI). Three groups of adolescents (12-16 years) underwent MRI: obese OSAS (n=56), obese controls (n=41) and lean controls (n=53). We studied 150 subjects and found that (1) obese adolescents with OSAS had increased adenotonsillar tissue compared to obese and lean controls; (2) obese OSAS adolescents had a smaller nasopharyngeal airway compared to controls; (3) the size of other upper airway soft tissue structures (volume of the tongue, parapharyngeal fat pads, lateral walls, soft palate) was similar between OSAS and obese controls; (4) although there were no major craniofacial abnormalities in most adolescents with OSAS, the ratio of soft tissue to craniofacial space surrounding the airway was increased; and (5) there were gender differences in the pattern of lymphoid proliferation. Increased size of the pharyngeal lymphoid tissue, rather than enlargement of the upper airway soft tissue structures, is the primary anatomic risk factor for OSAS in obese adolescents. These results are important for clinical decision making, and suggest that adenotonsillectomy should be considered as the initial treatment for OSAS in obese adolescents, a group with poor CPAP adherence and difficulty achieving weight loss.
    No preview · Article · Apr 2015 · American Journal of Respiratory and Critical Care Medicine
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    ABSTRACT: Objectives/HypothesisTo quantitatively measure volumetric changes in upper airway soft tissue structures using magnetic resonance imaging (MRI) pre- and post transoral robotic surgery for obstructive sleep apnea (OSA-TORS).Study DesignProspective, nonrandomized, institutional board-approved study.Methods Apneics undergoing OSA-TORS, which included bilateral posterior hemiglossectomy with limited pharyngectomy and uvulopalatopharyngoplasty, had upper airway MRIs pre- and postoperatively. Changes (percent and absolute values) in upper airway and surrounding soft tissue volumes were calculated. We assessed whether there were significant volumetric changes and if changes correlated with apnea-hypopnea index (AHI) changes.ResultsNineteen MRIs and 18 polysomnograms were analyzed pre- and postoperation. Total airway volume increased by 19.4% (P = 0.030). Soft palate and tongue volumes decreased by 18.3% (P = 0.002) and 5.8% (P = 0.013), respectively. Retropalatal and total lateral wall volumes decreased by 49.8% (P = 0.0001) and 17.9% (P = 0.008), respectively. Changes in other structures were not significant. Eleven patients had surgical success, with a mean AHI decrease of 52.9; six were nonsuccesses with a mean AHI decrease of 4.5 (P =0.006). Decreased retropalatal lateral wall volume correlated with decreased AHI.Conclusion Airway, tongue, soft palate, and lateral wall volumes change significantly after OSA-TORS. Changes in the volume of the lateral walls correlated with changes in AHI. Volumetric upper airway MRI may be a helpful tool to better understand reasons for surgical success.Level of Evidence4. Laryngoscope, 2015
    No preview · Article · Apr 2015 · The Laryngoscope
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    ABSTRACT: Sleep is an important physiologic process and lack of sleep is associated with a host of adverse outcomes. In addition, both basic and clinical research has documented the important role circadian rhythm plays in biologic function. Critical illness is a time of extreme vulnerability for patients and the important role sleep may play in recovery for ICU patients is just beginning to be explored. This concise clinical review will focus on the current state of research examining sleep in critical illness. We will discuss sleep and circadian rhythm abnormalities that occur in ICU patients and the challenges to measuring alterations in circadian rhythm in critical illness. In addition we will review methods to measure sleep in the ICU including polysomnography, actigraphy and questionnaires. We will discuss data on the impact of potentially modifiable disruptors to patient sleep, such as noise, light and patient care activities, and report on potential methods to improve sleep in the setting of critical illness. Finally we will review the latest literature on sleep disturbances that persist or develop after critical illness.
    No preview · Article · Jan 2015 · American Journal of Respiratory and Critical Care Medicine
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    ABSTRACT: Accumulating evidence has shown that there is a genetic contribution to obstructive sleep apnea (OSA).The objectives were to use magnetic resonance imaging (MRI) cephalometry to (1) confirm heritability of craniofacial risk factors for OSA previously shown by cephalometrics; and (2) examine the heritability of new craniofacial structures that are measurable with MRI.
    No preview · Article · Oct 2014 · Sleep
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    ABSTRACT: Study objectives: The objective of this study was to determine whether tongue fat is increased in obese sleep apneics compared to obese subjects without sleep apnea. We hypothesized that excess fat is deposited in the tongue in obese patients with sleep apnea. Design: Case-control design. Setting: Academic medical center. Patients: We examined tongue fat in 31 obese controls (apnea-hypopnea index, 4.1 ± 2.7 events/h) and 90 obese apneics (apnea-hypopnea index, 43.2 ± 27.3 events/h). Analyses were repeated in a subsample of 18 gender-, race-, age-, and BMI-matched case-control pairs. Interventions: All subjects underwent a MRI with three-point Dixon magnetic resonance imaging. We used sophisticated volumetric reconstruction algorithms to study the size and distribution of upper airway fat deposits in the tongue and masseter muscles within apneics and obese controls. Measurements and results: The data supported our a priori hypotheses that after adjustment for age, BMI, gender, and race, the tongue in apneics was significantly larger (P = 0.001) and had an increased amount of fat (P = 0.002) compared to controls. Similar results were seen in our matched sample. Our data also demonstrate that within the apneic and normal tongue, there are regional differences in fat distribution, with larger fat deposits at the base of the tongue. Conclusions: There is increased tongue volume and deposition of fat at the base of tongue in apneics compared to controls. Increased tongue fat may begin to explain the relationship between obesity and obstructive sleep apnea.
    Full-text · Article · Oct 2014 · Sleep
  • Shilpa R Kauta · Brendan T Keenan · Lee Goldberg · Richard J Schwab
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    ABSTRACT: Sleep disordered breathing (SDB) is associated with significant cardiovascular sequelae and positive airway pressure (PAP) has been shown to improve heart failure and prevent the recurrence of atrial fibrillation in cardiac patients with sleep apnea. Patients who are hospitalized with cardiac conditions frequently have witnessed symptoms of SDB but often do not have a diagnosis of sleep apnea. We implemented a clinical paradigm to perform unattended sleep studies and initiate treatment with PAP in hospitalized cardiac patients with symptoms consistent with SDB. We hypothesized that PAP adherence in cardiac patients with SDB would reduce readmission rates 30 days after discharge.
    No preview · Article · Sep 2014 · Journal of clinical sleep medicine: JCSM: official publication of the American Academy of Sleep Medicine
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    ABSTRACT: Rationale: Body habitus is a major determinant of obstructive sleep apnea (OSA). However, many individuals do not have OSA despite being overweight/obese (body mass index, BMI>25 kg/m2) for reasons that are not fully elucidated. Objectives: To determine the key physiological traits (upper-airway anatomy/collapsibility, upper-airway muscle responsiveness, chemoreflex control of ventilation, arousability from sleep) responsible for the absence of OSA in overweight/obese individuals. Methods: We compared key physiological traits in 18 overweight/obese non-apneics (apnea-hypopnea index, AHI<15 events/hr) to 25 overweight/obese matched OSA patients (AHI≥15 events/hr), and 11 normal-weight non-apneic controls. Traits were measured by repeatedly lowering continuous positive airway pressure to sub-therapeutic levels for 3 min during non-REM sleep. Measurements and Main Results: Overweight/obese non-apneics exhibited a less collapsible airway than overweight/obese apneics (Pcrit: -3.7±1.9 vs. 0.6±1.2 cmH2O, P=0.003; mean±95%CI.), but a more collapsible airway relative to normal-weight controls (-8.8±3.1 cmH2O, P<0.001). Notably, overweight/obese non-apneics exhibited a 3-fold greater upper-airway muscle responsiveness than both overweight/obese apneics (Δgenioglossus EMG/Δepiglottic pressure: -0.49[-0.22 to -0.79] vs. -0.15[-0.09 to -0.22] %/cmH2O, P=0.008; mean[95%CI]) and normal-weight controls (-0.16[-0.04 to -0.30] %/cmH2O; P=0.02). Loop gain was elevated (more-negative) in both overweight/obese groups vs. normal-weight controls (p=0.02). Model-based analysis demonstrated that overweight/obese non-apneics rely on both more favorable anatomy/collapsibility and enhanced upper-airway dilator muscle responses to avoid OSA. Conclusions: Overweight/obese non-apneics have a moderately-compromised upper-airway structure that is mitigated by highly-responsive upper-airway dilator muscles to avoid OSA. Elucidating the mechanisms underlying enhanced muscle responses in this population may provide clues for novel OSA interventions.
    Full-text · Article · Sep 2014 · American Journal of Respiratory and Critical Care Medicine
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    ABSTRACT: Objectives: Determine the relationship between surgical success and both preoperative drug-induced sleep endoscopy (DISE) airway caliber changes and volumetric magnetic resonance imaging (MRI) in patients with obstructive sleep apnea (OSA) undergoing transoral robotic assisted posterior glossectomy and uvulopalatopharyngoplasty (OSA-TORS).
    No preview · Article · Sep 2014 · Otolaryngology Head and Neck Surgery
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    ABSTRACT: Background Elevated levels of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) may contribute to cardiovascular disease and are associated with obstructive sleep apnea (OSA) and obesity. The relationship between OSA and obesity in determining ICAM-1 and VCAM-1 levels, and the effect of treatment, is unclear.Objective Our aim was to study whether positive airway pressure (PAP) usage resulted in changes in ICAM-1 and VCAM-1 after 2 years within 309 OSA patients from the Icelandic Sleep Apnea Cohort, and determine how obesity affected such changes.Subjects/Methods The mean body mass index (BMI) was 32.4±5.1 kg/m(2); subjects had moderate-to-severe OSA (apnea-hypopnea index=45.0±20.2) and 79% were male. There were 177 full PAP users (⩾4 hours/night and ⩾20 of last 28 nights), 44 partial (<4 hours/night or <20 nights), and 88 non-users.ResultsICAM-1 (P<0.001) and VCAM-1 (P=0.012) change was significantly different among the PAP groups. The largest ICAM-1 differences were among the most obese subjects (P<0.001). At follow-up, non-users had increased ICAM-1 compared to decreased levels in full users. All groups had increased VCAM-1, but non-users had a significantly larger increase than full users.Conclusion Within moderate-to-severe OSA patients, PAP usage prevents increases in adhesion molecules observed in non-users after two years. For ICAM-1, the largest effect is in the most obese subjects. As OSA and obesity commonly coexist, the usage of PAP to limit increases in adhesion molecules may decrease the rate of progression of OSA-related cardiovascular disease.International Journal of Obesity accepted article preview online, 21 July 2014; doi:10.1038/ijo.2014.123.
    Full-text · Article · Jul 2014 · International Journal of Obesity
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    ABSTRACT: Study Objectives: The objective of this study was to explore the mechanism of action of the oral pressure therapy (OPT) device, a new treatment for sleep apnea. Design: Case series. Setting: Academic medical center. Patients: Fifteen subjects with sleep apnea who had been successfully treated (responders) with the OPT device and 4 subjects who were not successfully treated (non-responders) with the OPT device. Interventions: All subjects underwent a MRI (without the device, with the device in place without vacuum and with the device in place with vacuum) to examine the biomechanical changes associated with the OPT device. Measurements and Results: Oral pressure therapy significantly (P = 0.002) increased the size of the retropalatal airway in both the lateral and anterior-posterior dimensions by moving the soft palate anteriorly and superiorly and the anterior-superior segment of the tongue forward, toward the teeth. The percentage and absolute increase in the cross-sectional area of the retropalatal region, the superior movement of the soft palate, and the anterior displacement of the tongue were significantly greater in the responders than in the non-responders. In responders, there were significant increases in the mean (P = 0.002), maximum (P = 0.0002), and minimum (P = 0.04) cross-sectional areas of the retropalatal region with the OPT device. However, in the retroglossal region, airway caliber decreased with the OPT device. Conclusions: In those who responded to oral pressure therapy, it increased airway caliber in the retropalatal region by moving the soft palate anteriorly and superiorly and the anterior-superior segment of the tongue forward.
    No preview · Article · Jul 2014 · Sleep
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    ABSTRACT: Study Objectives: Obesity is the most important risk factor for obstructive sleep apnea (OSA), and the effects of obesity may be mediated by tongue fat. Our objective was to examine the effects of obesity on upper airway structures in obese (OBZ) and non-obese (NBZ) Zucker rats. Design: Animal study. Setting: Academic Medical Center. Participants: OBZ (638.2 +/- 39 g; 14.9 +/- 1.1 w) and age-matched NBZ Zucker (442.6 +/- 37 g, 15.1 +/- 1.5 w) rats. Interventions: Tongue fat and volume and were assessed using: in vivo magnetic resonance spectroscopy (MRS), magnetic resonance imaging including Dixon imaging for tongue fat volume, ex vivo biochemistry (fat quantification; triglyceride (mg)/tissue (g), and histology (Oil Red O stain). Measurements and Results: MRS: overall OBZ tongue fat/water ratio was 2.9 times greater than NBZ (P < 0.002) with the anterior OBZ tongue up to 3.3 times greater than NBZ (P < 0.002). Biochemistry: Triglyceride (TG) in the tongue was 4.4 times greater in OBZ versus NBZ (P <0.0006). TG was greater in OBZ tongue (3.57 +/- 1.7 mg/g) than OBZ masseter muscle (0.28 +/- 0.1; P < 0.0001) but tongue and masseter TG were not different in NBZ rats (0.82 +/- 0.3 versus 0.28 +/- 0.1 mg/g, P = 0.67). Dixon fat volume was significantly increased in OBZ (56 +/- 15 mm(3)) versus NBZ (34 +/- 5 mm3, P < 0.004). Histology demonstrated a greater degree of intracellular muscle fat and extramuscular fat infiltration in OBZ versus NBZ rats. Conclusions: Genetically obese rats had a large degree of fat infiltration in the tongue compared to both skeletal muscle and tongue tissues of the non-obese age-matched littermates. The significant fat increase and sequestration in the obese tongue may play a role in altered tongue neuromuscular function, tongue stiffness or metabolic function.
    No preview · Article · Jun 2014 · Sleep
  • G W Pien · B Keenan · B A Staley · W Wieland · S Hurley · C L Marcus · R J Schwab
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    ABSTRACT: Body Correlations between UA Soft Tissue Structures and Pcrit
    No preview · Conference Paper · May 2014
  • G W Pien · B Keenan · B A Staley · W Wieland · S Hurley · C L Marcus · R J Schwab
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    ABSTRACT: Body Correlations between UA Soft Tissue Structures and Pcrit
    No preview · Conference Paper · May 2014
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    ABSTRACT: Obstructive sleep apnoea (OSA) is associated with cardiovascular disease. Dyslipidaemia has been implicated as a mechanism linking OSA with atherosclerosis, but no consistent associations with lipids exist for OSA or positive airway pressure treatment. We assessed the relationships between fasting lipid levels and obesity and OSA severity, and explored the impact of positive airway pressure treatment on 2-year fasting lipid level changes. Analyses included moderate-to-severe OSA patients from the Icelandic Sleep Apnoea Cohort. Fasting morning lipids were analysed in 613 untreated participants not on lipid-lowering medications at baseline. Patients were then initiated on positive airway pressure and followed for 2 years. Sub-classification using propensity score quintiles, which aimed to replicate covariate balance associated with randomised trials and, therefore, minimise selection bias and allow causal inference, was used to design the treatment group comparisons. 199 positive airway pressure adherent patients and 118 non-users were identified. At baseline, obesity was positively correlated with triglycerides and negatively correlated with total cholesterol, and low-density and high-density lipoprotein cholesterol. A small correlation was observed between the apnoea/hypopnoea index and high-density lipoprotein cholesterol. No effect of positive airway pressure adherence on 2-year fasting lipid changes was observed. Results do not support the concept of changes in fasting lipids as a primary mechanism for the increased risk of atherosclerotic cardiovascular disease in OSA.
    No preview · Article · May 2014 · European Respiratory Journal
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    ABSTRACT: Study Objectives: (1) To determine whether facial phenotype, measured by quantitative photography, relates to underlying craniofacial obstructive sleep apnea (OSA) risk factors, measured with magnetic resonance imaging (MRI); (2) To assess whether these associations are independent of body size and obesity. Design: Cross-sectional cohort. Setting: Landspitali, The National University Hospital, Iceland. Participants: One hundred forty patients (87.1% male) from the Icelandic Sleep Apnea Cohort who had both calibrated frontal and profile craniofacial photographs and upper airway MRI. Mean +/- standard deviation age 56.1 +/- 10.4 y, body mass index 33.5 +/- 5.05 kg/m(2), with on-average severe OSA (apnea-hypopnea index 45.4 +/- 19.7 h(-1)). Interventions: N/A. Measurements and Results: Relationships between surface facial dimensions (photos) and facial bony dimensions and upper airway softtissue volumes (MRI) was assessed using canonical correlation analysis. Photo and MRI craniofacial datasets related in four significant canonical correlations, primarily driven by measurements of (1) maxillary-mandibular relationship (r = 0.8, P < 0.0001), (2) lower face height (r = 0.76, P < 0.0001), (3) mandibular length (r = 0.67, P < 0.0001), and (4) tongue volume (r = 0.52, P = 0.01). Correlations 1, 2, and 3 were unchanged when controlled for weight and neck and waist circumference. However, tongue volume was no longer significant, suggesting facial dimensions relate to tongue volume as a result of obesity. Conclusions: Significant associations were found between craniofacial variable sets from facial photography and MRI. This study confirms that facial photographic phenotype reflects underlying aspects of craniofacial skeletal abnormalities associated with OSA. Therefore, facial photographic phenotyping may be a useful tool to assess intermediate phenotypes for OSA, particularly in large-scale studies.
    No preview · Article · May 2014 · Sleep
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    ABSTRACT: Rationale: The metabolic activity of the tongue is unknown in patients with sleep apnea. Tongue EMG activity has been shown to be increased in apneics. This increase in tongue EMG activity is thought to be related to increased neuromuscular compensation or denervation/reinnervation of the muscle fibers. Increased glucose uptake in the tongue would support increased neuromuscular compensation, whereas decreased glucose uptake in the tongue would support denervation/reinnervation of the muscle fibers. Objectives: To investigate the metabolic activity of the genioglossus and control upper airway muscles in obese apneics compared to obese controls. Methods: Subjects underwent a standard overnight sleep study to determine an apnea-hypopnea index (AHI); positron emission tomography with [18F]-2-fluoro-2-deoxy-D-glucose (FDG) and magnetic resonance imaging. We quantified glucose uptake by obtaining the standardized uptake value (SUV) within upper airway tissues. Main Results: We recruited 30 obese control subjects (AHI: 4.7±3.1 events/hour) and 72 obese apneics (AHI: 43.5±28.0 events/hour). Independent of age, BMI, gender and race, apneics had significantly reduced glucose uptake in the genioglossus (p=0.03) in comparison to controls. No differences in SUV were found in the masseter (p=0.38), pterygoid (p=0.70) or in neck (p=0.44) and submental (p=0.95) fat deposits between apneics and controls. Conclusions: There was significantly reduced glucose uptake in the genioglossus of apneics in comparison to obese controls. The reduction in glucose uptake was likely secondary to alterations in tongue muscle fiber type or to chronic denervation. The reduced glucose uptake argues against the neuromuscular compensation hypothesis explaining the increase in tongue EMG activity in apneics.
    Full-text · Article · Apr 2014 · American Journal of Respiratory and Critical Care Medicine
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    ABSTRACT: Symptoms of sleep-disordered breathing (SDB) are common among pregnant women, and several studies link SDB symptoms with gestational hypertension and preeclampsia. However, few prospective studies objectively measuring SDB during pregnancy have been performed. We performed a prospective cohort study examining risk factors for third trimester SDB in pregnant women. 105 pregnant women from the Hospital of the University of Pennsylvania obstetrics practices completed first and third trimester overnight polysomnography studies. We examined whether the number of SDB events per hour of sleep increased during pregnancy. We performed unadjusted and multivariable logistic regression analyses to estimate the effects of usual and pregnancy-specific characteristics on development of third trimester obstructive sleep apnoea (OSA). In secondary analyses, we examined the relationship between objectively measured SDB, hypertensive disorders of pregnancy, and other adverse maternal-fetal outcomes. Mean Apnoea-Hypopnoea Index increased from 2.07 (SD 3.01) events/h at baseline (first trimester) to 3.74 (SD 5.97) in the third trimester (p=0.009). 10.5% of women had OSA in the first trimester. By the third trimester, 26.7% of women had OSA. In multivariable analyses, first trimester body mass index (BMI) and maternal age were significantly associated with third trimester OSA. Third trimester OSA is common. Risk factors for third trimester OSA among women without baseline SDB include higher baseline BMI and maternal age.
    No preview · Article · Nov 2013 · Thorax
  • S Senapati · C R Gracia · E W Freeman · M D Sammel · H Lin · C Kim · R J Schwab · G W Pien
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    ABSTRACT: Objective: Reproductive hormone levels are associated with body size, and the association between estradiol and body size varies over the menopausal transition. This study aims to delineate these relationships using quantitative measures of visceral and subcutaneous fat. Methods: Early follicular hormones (follicle stimulating hormone (FSH), estradiol, luteinizing hormone, dehydroepiandrosterone sulfate, testosterone) and T-1 weighted abdominal MRI images were obtained in a cross-sectional assessment of 77 women in the Penn Ovarian Aging Study. Fat volume (cm(3)) was quantified using validated software (Amira) and divided into tertiles of visceral and subcutaneous fat volume for analysis. Multivariable linear regression models compared hormone values between tertiles adjusting for race, age, and menopausal status. Results: In adjusted models, estradiol was positively associated with visceral fat tertiles (geometric mean (GM) estradiol (pg/ml): Low 13.0, Mid 17.5, High 26.7, p = 0.006) while FSH was inversely associated with visceral fat tertiles (GM FSH (mIU/ml): Low 42.8, Mid 43.2, High 30.8, p = 0.03). The association of estradiol with visceral and subcutaneous fat tertiles varied by menopausal status (p < 0.001). In the early transition, estradiol was similar across tertiles of fat; postmenopause, estradiol was positively associated with visceral fat. Other hormones were not associated with fat measures. Conclusions: Estradiol was associated with quantitative measures of visceral fat and varies by menopausal status. This finding suggests that visceral fat may be an important mediator in hormone changes over the menopausal transition.
    No preview · Article · Sep 2013 · Climacteric

Publication Stats

4k Citations
464.16 Total Impact Points

Institutions

  • 2002-2015
    • William Penn University
      Filadelfia, Pennsylvania, United States
    • The Children's Hospital of Philadelphia
      • Division of Pulmonary Medicine
      Philadelphia, PA, United States
  • 1999-2015
    • University of Pennsylvania
      • • Division of Sleep Medicine
      • • Department of Medicine
      • • Division of Pulmonary, Allergy and Critical Care
      Filadelfia, Pennsylvania, United States
  • 1993-2005
    • Hospital of the University of Pennsylvania
      • • Division of Pulmonary Allergy and Critical Care
      • • Department of Medicine
      Filadelfia, Pennsylvania, United States