Obstructive sleep apnea syndrome is associated with some components of metabolic syndrome

BACKGROUND: Obesity, hypertension, dyslipidemia, and hyperglycemia are prevalent in obstructive sleep apnea syndrome (OSAS). Metabolic syndrome, however, is defined by visceral fat obesity plus at least two of these factors. However, whether OSAS contributes to the development of metabolic syndrome has not been defined. We investigated whether the components of metabolic syndrome were associated with OSAS in nonobese patients. METHODS: We investigated the occurrence of hypertension, dyslipidemia, and hyperglycemia in 42 men with OSAS and 52 men without OSAS matched for age, body mass index (BMI), and visceral fat accumulation. RESULTS: Although serum levels of triglycerides, high-density lipoprotein cholesterol, and diastolic BP did not differ significantly between the two groups, fasting blood glucose (111 +/- 6 mg/dL vs 93 +/- 3 mg/dL) [mean +/- SE] and the percentage of hypertensive patients (45% vs 15%) were significantly higher in the group with OSAS. In addition, a significantly higher percentage of patients with OSAS (19% vs 4%) had at least two of the following: hypertension, hyperglycemia, and dyslipidemia. Logistic regression analysis showed that the apnea-hypopnea index value was the predictor of number of metabolic syndrome parameters such as hypertension, hyperglycemia, and dyslipidemia, while BMI and lowest arterial oxygen saturation during sleep did not. CONCLUSION: Independent of visceral fat obesity, OSAS was associated with hypertension, dyslipidemia, and hyperglycemia. It is possible that OSAS may predispose even nonobese patients to the development of metabolic syndrome.     

Endothelin-1/endothelin-3 ratio: a potential prognostic factor of pulmonary arterial hypertension

BACKGROUND: Pulmonary arterial hypertension (PAH) is a rare condition characterized by elevated pulmonary artery pressure leading to right-heart failure and death. Endothelin (ET)-1 has been shown to play a significant pathogenic role in PAH. ET-3 has not yet been investigated in PAH. METHODS: ET-1 and ET-3 plasma concentrations were measured in 33 PAH patients prior to any specific PAH therapy and in 9 control subjects. In PAH patients, hemodynamic parameters measured by right-heart catheterization, 6-min walk distance (6MWD), New York Heart Association (NYHA) functional class, and time until lung transplantation or death were recorded. RESULTS: In patients with PAH, levels of ET-1 were increased while those of ET-3 were decreased, as compared to control subjects (p < 0.005 for both comparisons). ET-1/ET-3 ratio varied little in control subjects, while it increased threefold in PAH patients (p < 0.0001). ET-1 correlated positively with right atrial pressure (RAP), indexed total pulmonary resistance, and negatively with cardiac index and venous saturation of oxygen (Svo(2)). ET-3 correlated positively with 6MWD. ET-1/ET-3 ratio correlated positively with RAP, negatively with Svo(2) and 6MWD, and was also associated with NYHA functional class. ET-1/ET-3 ratio was associated with prognosis in this sample of PAH patients treated with specific therapies. CONCLUSIONS: PAH is characterized by elevated ET-1 and ET-1/ET-3 ratio and decreased ET-3 plasma concentrations. All of them correlate with hemodynamic and clinical markers of disease severity. ET-1/ET-3 ratio might be a novel prognostic factor in PAH. These preliminary data should be validated in a large prospective multicenter cohort of PAH patients.     

Atrial septostomy decreases sympathetic overactivity in pulmonary arterial hypertension

BACKGROUND: We have reported previously that the sympathetic nervous system is activated in patients with pulmonary arterial hypertension (PAH), and that this is only partly explained by a decrease in arterial oxygenation. Possible causes for increased muscle sympathetic nerve activity (MSNA) in patients with PAH include right atrial distension and decreased cardiac output. Both may be improved by atrial septostomy, but this intervention also further decreases arterial oxygenation. In the present study, we wanted to investigate the effect of atrial septostomy on MSNA in patients with PAH. METHODS: We recorded BP, heart rate (HR), arterial O2 saturation (SaO2), and MSNA before and after atrial septostomy in PAH patients (mean [+/- SE] age, 48 +/- 5 years) and in closely matched control subjects. Measurements were also performed after septostomy, while SaO2 was brought to the preprocedure level by supplemental O2 therapy. RESULTS: Compared to the control subjects (n = 10), the PAH patients (n = 11) had a lower mean BP (75 +/- 2 vs 96 +/- 3 mm Hg, respectively; p < 0.001), lower mean SaO2 (92 +/- 1% vs 97 +/- 0%, respectively; p < 0.001), increased mean HR (84 +/- 4 vs 68 +/- 3 beats/min; p < 0.01), and markedly increased mean MSNA (76 +/- 5 vs 29 +/- 2 bursts per minute; p < 0.001). Atrial septostomy decreased mean SaO2 (to 85 +/- 2%; p < 0.001) and mean MSNA (to 69 +/- 4 bursts per minute; p < 0.01), but did not affect HR or BP. Therapy with supplemental O2 did not affect MSNA, BP, or HR. The decrease in MSNA was correlated to the decrease in right atrial pressure (r = 0.62; p < 0.05). CONCLUSIONS: Atrial septostomy in PAH patients decreases sympathetic hyperactivity despite an associated decrease in arterial oxygenation, and this appears to be related to decreased right atrial distension.     

Platelet-derived growth factor is increased in pulmonary capillary hemangiomatosis

Background:Pulmonary capillary hemangiomatosis (PCH) is a rare cause of pulmonary arterial hypertension with no effective medical therapy and a high risk of mortality. The pathogenesis of PCH is unknown.Methods:We used gene expression analysis to compare lung tissue samples from two patients with PCH to those from seven control subjects. The nodules of proliferating capillaries in PCH patients were needle microdissected from cryostat sections. RNA extraction and labeling were followed by hybridization to U95Av2 oligonucleotide arrays (Affymetrix; Santa Clara, CA).In situhybridization and immunohistochemistry were also performed.Results:The gene expression profile of PCH allowed for unsupervised clustering from the profile of the lung tissue samples of control subjects. Platelet-derived growth factor (PDGF)-B gene (PDGFB), PDGF receptor (PDGFR)-β gene (PDGFR-β), mast cell-related genes, and type 2 pneumocyte-related genes were found to be overexpressed in PCH lesions.In situhybridization as well as immunohistochemistry for PDGFB showed expression by type 2 pneumocytes and endothelial cells. Immunohistochemical staining for PDGFR-β localized to pericytic/vascular smooth muscle cells surrounding the proliferating capillaries. CD117 staining confirmed an abundance of mast cells in the lesions, which also stained heavily for PDGFR-β.Conclusions:The expression of thePDGFBandPDGFR-β genes characterizes the nodular proliferations of PCH. Increased numbers of mast cells, pericytes, and type II pneumocytes accompany the endothelial proliferation. The up-regulation of these important angiogenic and antiapoptotic genes suggests a mechanism and potential therapeutic approaches for PCH.     

Persistent airway obstruction after virus infection is not associated with airway inflammation

BACKGROUND: This study examined the contribution of airway inflammation to the delayed lung function recovery that occurs in some people following virus-induced asthma exacerbations. METHODS: Subjects (n = 40) were recruited at hospital admission for acute asthma exacerbation. Respiratory virus infection was diagnosed by viral nucleic acid detection and/or cell culture, using induced sputum, nasal, or throat swabs. Data collected included lung function, answers to common cold and asthma control questionnaires, and induced sputum cellular profiles. Subjects were reexamined 4 to 6 weeks postexacerbation and were compared with stable asthmatic subjects (n = 26) who had been recruited from ambulatory care clinics. RESULTS: Persistent airway obstruction, defined as lung function improvement at follow-up (ie, change in FEV1 percent predicted [Delta%FEV1]) of <15%, was observed in 10 subjects (25%). Airway recovery (Delta%FEV1, > or = 15%) was observed in the remaining subjects (30 subjects; 75%). During the acute episode, the airway-recovery group had increased total cell count (p = 0.019), increased number of neutrophils (p = 0.005), and increased percentage of neutrophils (p = 0.0043) compared to the group of stable subjects with asthma. Postexacerbation, the airway-recovery group had reduced numbers of neutrophils and an increased percentage of eosinophils. In contrast, during exacerbation, subjects with persistent airway obstruction showed no differences in inflammatory cell counts compared to stable subjects with asthma, nor did cell counts change postexacerbation. Symptoms improved in both groups postexacerbation. However, in the persistent-airway-obstruction group, asthma remained uncontrolled. CONCLUSION: Persistent airway obstruction and uncontrolled asthma are observed in some people after viral asthma exacerbations. These abnormalities are not associated with inflammatory cell influx into the airway lining fluid during the exacerbation and may reflect the involvement of noncellular elements. Further work should explore other mechanisms leading to incomplete airway recovery.     

Improvement of pulmonary hypertension after liver transplantation.

Pulmonary hypertension at the end stage of chronic liver disease is not an uncommon situation. This association termed portopulmonary hypertension raises the question of the feasibility of performing orthotopic liver transplantation (OLT). In the case reported herein, there was a favorable outcome after OLT, even though the mean pulmonary artery pressure (MPAP) before transplantation was increased to 45 mm Hg. Before OLT, the cardiac index (CI) was considerably elevated (7.69 L/min/m2), giving evidence of a marked hyperdynamic circulatory state. The CI decreased significantly after OLT (3.38 L/min/m2), and this produced a significant decrease in the MPAP. Our observation suggests that portopulmonary hypertension due to a marked increase in the CI can be managed successfully by OLT.     

Airway nitric oxide in patients with cystic fibrosis is associated with pancreatic function, Pseudomonas infection, and polyunsaturated fatty acids

BACKGROUND: Airway nitric oxide (NO) is low or normal in cystic fibrosis (CF) patients. This may affect bacterial status since NO has antimicrobial properties. Arachidonic acid (AA), which is increased in the serum and airways of CF patients, has been shown to reduce NO levels. The aim of this study was to investigate whether airway NO level correlates with genotype and pancreatic function, and whether low airway NO level is associated with bacterial infection and increased serum AA level in CF patients. METHOD: Nasal NO (nNO) and exhaled NO (eNO) were measured according to the European Respiratory Society/American Thoracic Society standard in 59 CF patients aged 7 to 55 years, 80% of whom were pancreatic insufficient (PI) and 51% were chronically infected with Pseudomonas aeruginosa. RESULTS: PI CF patients had significantly lower nNO levels than pancreatic-sufficient (PS) patients. Airway NO level did not correlate with lung function or inflammatory parameters. PI patients chronically infected with P aeruginosa had significantly lower nNO levels than noninfected PI patients. nNO level correlated inversely with the AA/docosahexaenoic acid ratio, and eNO with the essential fatty acid (FA) deficiency index, which is the ratio between mead acid and AA. CONCLUSIONS: CF patients with PI, which is associated with more severe genotypes, had lower airway NO levels than patients with PS. Low NO level was correlated to chronic P aeruginosa infection, and an association was found between airway NO level and the abnormal serum phospholipid FA pattern.     

Plasma aldosterone is related to severity of obstructive sleep apnea in subjects with resistant hypertension

OBJECTIVE: Obstructive sleep apnea (OSA) and primary aldosteronism are common in subjects with resistant hypertension; it is unknown, however, if the two disorders are causally related. This study relates plasma aldosterone and renin levels to OSA severity in subjects with resistant hypertension, and in those with equally severe OSA but without resistant hypertension serving as control subjects. METHODS: Seventy-one consecutive subjects referred to the University of Alabama at Birmingham (UAB) for resistant hypertension (BP uncontrolled on three medications) and 29 control subjects referred to UAB Sleep Disorders Center for suspected OSA were prospectively evaluated by an early morning plasma aldosterone concentration (PAC) and renin level, and by overnight, attended polysomnography. RESULTS: OSA (apnea-hypopnea index [AHI] > or = 5/h) was present in 85% of subjects with resistant hypertension. In these subjects, PAC correlated with AHI (rho = 0.44, p = 0.0002) but not renin concentration. Median PAC was significantly lower in control subjects compared to subjects with resistant hypertension (5.5 ng/dL vs 11.0 ng/dL, p < 0.05) and not related to AHI. In male subjects compared to female subjects with resistant hypertension, OSA was more common (90% vs 77%) and more severe (median AHI, 20.8/h vs 10.8/h; p = 0.01), and median PAC was significantly higher (12.0 ng/dL vs 8.8 ng/dL, p = 0.006). CONCLUSION: OSA is extremely common in subjects with resistant hypertension. A significant correlation between PAC and OSA severity is observed in subjects with resistant hypertension but not in control subjects. While cause and effect cannot be inferred, the data suggest that aldosterone excess may contribute to OSA severity.     

Quadriceps weakness is related to exercise capacity in idiopathic pulmonary fibrosis

STUDY OBJECTIVE: In COPD, it has been shown that peripheral muscle dysfunction is a factor determining exercise intolerance. We examined the hypothesis that exercise capacity of patients with idiopathic pulmonary fibrosis (IPF) is, at least in part, determined by peripheral muscle dysfunction. METHODS: Maximum oxygen uptake (V(O2)max) was evaluated in 41 consecutive patients with IPF, along with potential determinants of exercise capacity, both in the lungs and in the peripheral muscles. RESULTS: Patients had reduced V(O2)max (893 +/- 314 mL, 46.0% predicted) and reduced quadriceps force (QF) [65% predicted]. Significant correlates of V(O2)max reduction were vital capacity (VC) [r = 0.79], total lung capacity (r = 0.64), diffusion capacity (r = 0.64), QF (r = 0.62), maximum expiratory pressure (r = 0.48), and Pa(O2) at rest (r = 0.33). In stepwise multiple regression analysis, VC and QF were independent predictors of V(O2)max. Furthermore, in subgroup analysis, QF was a significant contributing factor for V(O2)max in patients who discontinued exercise because of dyspnea and/or leg fatigue. CONCLUSIONS: We conclude that QF is a predictor of exercise capacity in IPF. Measures that improve muscle function might improve exercise tolerance.     

Right and left ventricular function and pulmonary artery pressure in patients with bronchiectasis

BACKGROUND: Bronchiectasis may have deleterious effects on cardiac function secondary to pulmonary hypertension (PH). This study was designed to assess cardiac function and determine the prevalence of PH in patients with cystic and cylindrical bronchiectasis. METHODS: A cross-sectional study of patients with bronchiectasis diagnosed by CT scan was conducted at King Khalid University Hospital, Riyadh, Saudi Arabia between December 2005 and January 2007. Pulmonary function tests were performed, arterial blood gas measurements were made, and cardiac function and systolic pulmonary artery pressure (SPAP) were assessed by echocardiography. RESULTS: Of 94 patients (31% men, n = 29), 62 patients (66%) had cystic bronchiectasis and 32 patients (34%) had cylindrical bronchiectasis. Right ventricular (RV) systolic dysfunction was observed in 12 patients (12.8%), left ventricular (LV) systolic dysfunction was observed in 3 patients (3.3%), and LV diastolic dysfunction was observed in 11 patients (11.7%); all had cystic bronchiectasis. RV dimensions were significantly greater in the cystic bronchiectasis group, and were positively correlated with SPAP (p < 0.0001) and negatively correlated with Pao2 (p < 0.016). Other hemodynamic variables were not different between groups. PH in 31 patients (32.9%) was significantly greater in patients with cystic bronchiectasis compared with cylindrical bronchiectasis (p = 0.04). In cystic bronchiectasis, SPAP was positively correlated with Paco2 (p = 0.001), and inversely correlated with Pao2 (p = 0.03), diffusion capacity of the lung for carbon monoxide percentage (p = 0.02), and FEV1 (p = 0.02). CONCLUSIONS: RV systolic dysfunction and PH were more common than LV systolic dysfunction in bronchiectatic patients. LV diastolic dysfunction was mainly seen in severe PH. We recommend detailed assessment of cardiac function, particularly LV diastolic function, in patients with bronchiectasis.     

Atrial septostomy in treatment of end-stage right heart failure in patients with pulmonary hypertension

BACKGROUND: Right ventricular (RV) failure is the main cause of death in patients with pulmonary hypertension (PH). Balloon atrial septostomy (BAS) is believed to relieve symptoms of PH by increasing systemic flow and reducing RV preload. METHODS: Fourteen BAS procedures were performed in 11 patients (5 men and 6 women; mean [+/- SD] age, 33 +/- 12 years) with RV failure in the course of PH that was refractory to conventional treatment. BAS consisted of a puncture of the interatrial septum and subsequent dilatations with balloons of increasing diameter in a step-by-step manner. RESULTS: After BAS, the mean oxygen saturation of aortic blood decreased (before, 93 +/- 4%; after, 84 +/- 4%; p = 0.001), while mean cardiac index increased (before, 1.54 +/- 0.34 L/min/m(2); after, 1.78 +/- 0.35 L/min/m(2); p = 0.001), resulting in a positive trend for mean systemic oxygen transport (before, 270 +/- 64 mL/min; after, 286 +/- 81 mL/min; p = 0.08). Pulmonary vascular resistance (PVR) slightly increased immediately after the procedure, and this rise inversely correlated with mixed venous blood partial oxygen pressure both before BAS (r = -0.69; p = 0.009) and after BAS (r = -0.64; p = 0.018). Mean functional class improved from 3.2 +/- 0.4 to 2.6 +/- 0.7 (p = 0.03) after 1 month. At follow-up (mean time to follow-up, 8.1 +/- 6.2 months; range, 0.8 to 20.2 months), seven patients died and two underwent lung transplantation. There was no difference in the survival rate compared to that obtained from National Institutes of Health equation. A significant size reduction in the created defect was observed in six patients, requiring repeat BAS procedures in three cases. CONCLUSIONS: The current BAS technique improves cardiac index and functional class without significant periprocedural complications, except for a transient increase in PVR related to acute desaturation of mixed venous blood. At long-term follow-up, a high incidence of spontaneous decrease in orifice size has been observed.     

Clinical application of tissue Doppler imaging in patients with idiopathic pulmonary hypertension

BACKGROUND: Tissue Doppler (TD) echocardiographic imaging of mitral and tricuspid annulus has been applied to assess right ventricular (RV) and left ventricular (LV) function in many cardiac diseases, but its clinical application, including response to long-term targeted therapy in patients with idiopathic pulmonary hypertension (PH), has not been addressed. METHODS: Seventy patients with idiopathic PH were compared with 35 age-matched control subjects to examine myocardial velocities by TD. Of these, 35 patients underwent repeat imaging after long-term targeted therapy. In addition, 50 consecutive patients with idiopathic PH with simultaneous right-heart catheterization and echocardiography were examined. RESULTS: No significant differences were noted between PH patients and the control group in lateral mitral annulus systolic velocity and early diastolic velocity (Ea) by TD, but septal velocities were significantly lower (p < 0.01). With targeted therapy, myocardial velocities at the septum and RV free wall increased significantly (p < 0.05). Likewise, E/Ea ratio increased, albeit still in the normal range. In all 50 patients with invasive measurements, lateral E/Ea ratio readily identified normal mean pulmonary capillary wedge pressure (PCWP). CONCLUSIONS: TD imaging of the lateral mitral annulus can reliably predict the presence of normal/reduced mean PCWP in patients with idiopathic PH, and track the improvement in RV function and LV filling with long-term targeted therapy.     

A case-control study of obstructive sleep apnea-hypopnea syndrome in obese and nonobese chinese children

BACKGROUND: Obesity is a risk factor for obstructive sleep apnea-hypopnea syndrome (OSAHS) in adults. However, the prevalence of OSAHS in children is not clear, and the relationship between obesity and OSAHS remains controversial. METHODS: Obese children were recruited from the endocrinology, respiratory, and ear, nose, and throat clinics. Weight-matched, age-matched, and sex-matched children were recruited as control subjects. Standard questionnaires were administered, and a standardized physical examination was carried out. Lateral neck roentgenography, sleep polysomnography, full blood count, and arterial blood gas analysis were also performed. Children with body mass index z-scores of > 1.96 were considered to be obese. An adenoidal/nasopharygeal ratio of > 0.67 was considered to constitute adenotonsillar hypertrophy (ATH). OSAHS was defined as an apnea-hypopnea index (AHI) score of > 5 or obstructive apnea index (OAI) score of > 1. RESULTS: Ninety-nine obese children and 99 control subjects were recruited into the study. Obese patients had significantly higher AHI and OAI scores, and lower sleep efficiency and minimum arterial oxygen saturation (MinSao(2)) than control subjects. The prevalence of OSAHS was significantly higher in obese children with or without the ATH groups than their nonobese counterparts (odds ratio, 1.9 vs 108, respectively; 95% confidence interval, 1.21 to 4.7 vs 6.2 to 191, respectively). Obesity, tonsillar hypertrophy, and adenoid hypertrophy were independent risk factors for OSAHS (p < 0.001, p = 0.042, and p = 0.004, respectively). There was a positive correlation between the degree of obesity and AHI (r = 0.535; p < 0.001), and an inverse correlation between obesity and MinSao(2) (r = -0.507; p < 0.001). End-tidal CO(2), Paco(2), and bicarbonate levels were within the normal range. CONCLUSIONS: Obesity is a risk factor for OSAHS, and the degree of obesity is positively correlated with the severity of OSAHS.