Rearrangement of cell types in the rat carotid body neurogenic niche induced by chronic intermittent hypoxia.

The carotid body (CB) is a prototypical acute oxygen (O2 )-sensing organ that mediates reflex hyperventilation and increased cardiac output in response to hypoxaemia. CB overactivation, secondary to the repeated stimulation produced by the recurrent episodes of intermittent hypoxia, is believed to contribute to the pathogenesis of sympathetic hyperactivity present in sleep apnoea patients. Although CB functional plasticity induced by chronic intermittent hypoxia (CIH) has been demonstrated, the underlying mechanisms are not fully elucidated. Here, we show that CIH induces a small increase in CB volume and rearrangement of cell types in the CB, characterized by a mobilization of immature quiescent neuroblasts, which enter a process of differentiation into mature, O2 -sensing and neuron-like, chemoreceptor glomus cells. Prospective isolation of individual cell classes has allowed us to show that maturation of CB neuroblasts is paralleled by an upregulation in the expression of specific glomus cell genes involved in acute O2 -sensing. CIH enhances mitochondrial responsiveness to hypoxia in maturing neuroblasts as well as in glomus cells. These data provide novel perspectives on the pathogenesis of CB-mediated sympathetic overflow that may lead to the development of new pharmacological strategies of potential applicability in sleep apnoea patients. KEY POINTS: Obstructive sleep apnoea is a frequent condition in the human population that predisposes to severe cardiovascular and metabolic alterations. Activation of the carotid body, the main arterial oxygen-sensing chemoreceptor, by repeated episodes of hypoxaemia induces exacerbation of the carotid body-mediated chemoreflex and contributes to sympathetic overflow characteristic of sleep apnoea patients. In rats, chronic intermittent hypoxaemia induces fast neurogenesis in the carotid body with rapid activation of neuroblasts, which enter a process of proliferation and maturation into O2 -sensing chemoreceptor glomus cells. Maturing carotid body neuroblasts and glomus cells exposed to chronic intermittent hypoxia upregulate genes involved in acute O2 sensing and enhance mitochondrial responsiveness to hypoxia. These findings provide novel perspectives on the pathogenesis of carotid body-mediated sympathetic hyperactivation. Pharmacological modulation of carotid body fast neurogenesis could help to ameliorate the deleterious effects of chronic intermittent hypoxaemia in sleep apnoea patients.

Echocardiographic Changes with Positive Airway Pressure Therapy in Obesity Hypoventilation Syndrome. Long-Term Pickwick Randomized Controlled Clinical Trial.

Rationale: Obesity hypoventilation syndrome (OHS) has been associated with cardiac dysfunction. However, randomized trials assessing the impact of long-term noninvasive ventilation (NIV) or continuous positive airway pressure (CPAP) on cardiac structure and function assessed by echocardiography are lacking.Objectives: In a prespecified secondary analysis of the largest multicenter randomized controlled trial of OHS (Pickwick Project; N = 221 patients with OHS and coexistent severe obstructive sleep apnea), we compared the effectiveness of three years of NIV and CPAP on structural and functional echocardiographic changes.Methods: At baseline and annually during three sequential years, patients underwent transthoracic two-dimensional and Doppler echocardiography. Echocardiographers at each site were blinded to the treatment allocation. Statistical analysis was performed using a linear mixed-effects model with a treatment group and repeated measures interaction to determine the differential effect between CPAP and NIV.Measurements and Main Results: A total of 196 patients were analyzed: 102 were treated with CPAP and 94 were treated with NIV. Systolic pulmonary artery pressure decreased from 40.5 ± 1.47 mm Hg at baseline to 35.3 ± 1.33 mm Hg at three years with CPAP, and from 41.5 ± 1.56 mm Hg to 35.5 ± 1.42 with NIV (P < 0.0001 for longitudinal intragroup changes for both treatment arms). However, there were no significant differences between groups. NIV and CPAP therapies similarly improved left ventricular diastolic dysfunction and reduced left atrial diameter. Both NIV and CPAP improved respiratory function and dyspnea.Conclusions: In patients with OHS who have concomitant severe obstructive sleep apnea, long-term treatment with NIV and CPAP led to similar degrees of improvement in pulmonary hypertension and left ventricular diastolic dysfunction.Clinical trial registered with www.clinicaltrials.gov (NCT01405976).

Long-term clinical effectiveness of continuous positive airway pressure therapy versus non-invasive ventilation therapy in patients with obesity hypoventilation syndrome: a multicentre, open-label, randomised controlled trial.

BACKGROUND: Obesity hypoventilation syndrome is commonly treated with continuous positive airway pressure or non-invasive ventilation during sleep. Non-invasive ventilation is more complex and costly than continuous positive airway pressure but might be advantageous because it provides ventilatory support. To date there have been no long-term trials comparing these treatment modalities. We therefore aimed to determine the long-term comparative effectiveness of both treatment modalities. METHODS: We did a multicentre, open-label, randomised controlled trial at 16 clinical sites in Spain. We included patients aged 15-80 years with untreated obesity hypoventilation syndrome and an apnoea-hypopnoea index of 30 or more events per h. We randomly assigned patients, using simple randomisation through an electronic database, to receive treatment with either non-invasive ventilation or continuous positive airway pressure. Both investigators and patients were aware of the treatment allocation. The research team was not involved in deciding hospital treatment, duration of treatment in the hospital, and adjustment of medications, as well as adjudicating cardiovascular events or cause of mortality. Treating clinicians from the routine care team were not aware of the treatment allocation. The primary outcome was the number of hospitalisation days per year. The analysis was done according to the intention-to-treat principle. This study is registered with ClinicalTrials.gov, number NCT01405976. FINDINGS: From May 4, 2009, to March 25, 2013, 100 patients were randomly assigned to the non-invasive ventilation group and 115 to the continuous positive airway pressure group, of which 97 patients in the non-invasive ventilation group and 107 in the continuous positive airway pressure group were included in the analysis. The median follow-up was 5·44 years (IQR 4·45-6·37) for all patients, 5·37 years (4·36-6·32) in the continuous positive airway pressure group, and 5·55 years (4·53-6·50) in the non-invasive ventilation group. The mean hospitalisation days per patient-year were 1·63 (SD 3·74) in the continuous positive airway pressure group and 1·44 (3·07) in the non-invasive ventilation group (adjusted rate ratio 0·78, 95% CI 0·34-1·77; p=0·561). Adverse events were similar between both groups. INTERPRETATION: In stable patients with obesity hypoventilation syndrome and severe obstructive sleep apnoea, non-invasive ventilation and continuous positive airway pressure have similar long-term effectiveness. Given that continuous positive airway pressure has lower complexity and cost, continuous positive airway pressure might be the preferred first-line positive airway pressure treatment modality until more studies become available. FUNDING: Instituto de Salud Carlos III, Spanish Respiratory Foundation, and Air Liquide Spain.

Leptin acts in the carotid bodies to increase minute ventilation during wakefulness and sleep and augment the hypoxic ventilatory response.

KEY POINTS: Leptin is a potent respiratory stimulant. A long functional isoform of leptin receptor, LepRb , was detected in the carotid body (CB), a key peripheral hypoxia sensor. However, the effect of leptin on minute ventilation (VE ) and the hypoxic ventilatory response (HVR) has not been sufficiently studied. We report that LepRb is present in approximately 74% of the CB glomus cells. Leptin increased carotid sinus nerve activity at baseline and in response to hypoxia in vivo. Subcutaneous infusion of leptin increased VE and HVR in C57BL/6J mice and this effect was abolished by CB denervation. Expression of LepRb in the carotid bodies of LepRb deficient obese db/db mice increased VE during wakefulness and sleep and augmented the HVR. We conclude that leptin acts on LepRb in the CBs to stimulate breathing and HVR, which may protect against sleep disordered breathing in obesity. ABSTRACT: Leptin is a potent respiratory stimulant. The carotid bodies (CB) express the long functional isoform of leptin receptor, LepRb , but the role of leptin in CB has not been fully elucidated. The objectives of the current study were (1) to examine the effect of subcutaneous leptin infusion on minute ventilation (VE ) and the hypoxic ventilatory response to 10% O2 (HVR) in C57BL/6J mice before and after CB denervation; (2) to express LepRb in CB of LepRb -deficient obese db/db mice and examine its effects on breathing during sleep and wakefulness and on HVR. We found that leptin enhanced carotid sinus nerve activity at baseline and in response to 10% O2 in vivo. In C57BL/6J mice, leptin increased VE from 1.1 to 1.5 mL/min/g during normoxia (P < 0.01) and from 3.6 to 4.7 mL/min/g during hypoxia (P < 0.001), augmenting HVR from 0.23 to 0.31 mL/min/g/Δ FIO2 (P < 0.001). The effects of leptin on VE and HVR were abolished by CB denervation. In db/db mice, LepRb expression in CB increased VE from 1.1 to 1.3 mL/min/g during normoxia (P < 0.05) and from 2.8 to 3.2 mL/min/g during hypoxia (P < 0.02), increasing HVR. Compared to control db/db mice, LepRb transfected mice showed significantly higher VE throughout non-rapid eye movement (20.1 vs. -27.7 mL/min respectively, P < 0.05) and rapid eye movement sleep (16.5 vs 23.4 mL/min, P < 0.05). We conclude that leptin acts in CB to augment VE and HVR, which may protect against sleep disordered breathing in obesity.

Good long-term adherence to continuous positive airway pressure therapy in patients with resistant hypertension and sleep apnea.

Although adequate adherence is paramount in achieving the beneficial effects of continuous positive airway pressure therapy in patients with obstructive sleep apnea, long-term adherence and the variables involved in continuous positive airway pressure compliance in patients with resistant hypertension and obstructive sleep apnea are yet unknown. We conducted a prospective, multicentre, observational study in 177 patients recruited from hypertensive units with resistant hypertension confirmed by means of 24-hr blood pressure monitoring (blood pressure ≥ 130 and/or ≥ 80 mmHg, despite taking at least three antihypertensive drugs or < 130/80 mmHg with > 3 drugs) and obstructive sleep apnea (apnea-hypopnea index ≥ 5 in a respiratory polygraph) who were prescribed continuous positive airway pressure treatment. Good adherence was defined as an average cumulative continuous positive airway pressure use of ≥ 4 hr per night at the end of the follow-up. A multivariate Cox regression analysis was performed to identify independent predictors of continuous positive airway pressure adherence. Patients were followed for a median of 57.6 (42-72) months after initiating continuous positive airway pressure therapy. At the end of the follow-up, the median continuous positive airway pressure use was 5.7 (inter-quartile range 3.9-6.6) hr per night, and 132 patients (74.5%) showed good continuous positive airway pressure adherence. The only baseline variable associated with poor adherence was the presence of previous stroke (hazard ratio 4.00, 95% confidence interval 1.92-8.31). Adequate adherence at 1 month also predicted good adherence at the end of the follow-up (hazard ratio 14.4, 95% confidence interval 4.94-56). Both variables also predicted adherence at a threshold of 6 hr per night. Our results show that good continuous positive airway pressure adherence is an achievable and feasible goal in patients with resistant hypertension and obstructive sleep apnea. Previous stroke and short-term adherence predicted long-term adherence.

Prospective study to evaluate quality of life in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative rare disease characterized by symptoms and signs in the upper and lower motor neurons, leading to progressive neuro-degeneration and muscle atrophy. Our objective was to analyse the quality of life (QoL) in patients with ALS and compare with general population and with patients with cancer. Prospective study from consecutive ALS patients in one center. In order to assess quality of life, during the first visit three questionnaires were administered: Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS-R), Short Form-36 (SF-36) and EuroQoL 5D (EQ-5D). We compared SF-36 of ALS patients with a reference population (n = 9151), and we compared the EQ-5D index score of ALS patients versus patients with cancer in the same area and in the same period (2015-2018). Between June 2015 and September 2017, 23 were included. The mean age was 65.1 ± 12.6 years and 56.5% were women. Compared with the general population, patients with ALS showed lowest QoL (p < 0.05) in all the dimensions, with a very important impairment in physical function (median: 0; p25-75: 0-10) and physical role (median: 0; p25-75: 0-6.25). In EQ-5D questionnaire, patients with ALS presented an EQ-5D index score of 0.21 ± 0.39 (mean ± standard deviation) with a visual analog scale (VAS) score of 0.32 ± 0.24. Compared with an oncological population, patients with ALS had a worse EQ-5D index score both clinically and statistically (0.21 ± 0.39 vs. 0.77 ± 0.27; p < 0.05). We demonstrate a poorer quality of life in patients with ALS is poor, and clinically and statistically worse than in patients with cancer or general population. New studies need to evaluate the impact of strategies in this population to improve the quality of life.

Effectiveness of CPAP vs. Noninvasive Ventilation Based on Disease Severity in Obesity Hypoventilation Syndrome and Concomitant Severe Obstructive Sleep Apnea.

RATIONALE: Obesity hypoventilation syndrome (OHS) with concomitant severe obstructive sleep apnea (OSA) is treated with CPAP or noninvasive ventilation (NIV) during sleep. NIV is costlier, but may be advantageous because it provides ventilatory support. However, there are no long-term trials comparing these treatment modalities based on OHS severity. OBJECTIVE: To determine if CPAP have similar effectiveness when compared to NIV according to OHS severity subgroups. METHODS: Post hoc analysis of the Pickwick randomized clinical trial in which 215 ambulatory patients with untreated OHS and concomitant severe OSA, defined as apnoea-hypopnea index (AHI)≥30events/h, were allocated to NIV or CPAP. In the present analysis, the Pickwick cohort was divided in severity subgroups based on the degree of baseline daytime hypercapnia (PaCO2 of 45-49.9 or ≥50mmHg). Repeated measures of PaCO2 and PaO2 during the subsequent 3 years were compared between CPAP and NIV in the two severity subgroups. Statistical analysis was performed using linear mixed-effects model. RESULTS: 204 patients, 97 in the NIV group and 107 in the CPAP group were analyzed. The longitudinal improvements of PaCO2 and PaO2 were similar between CPAP and NIV based on the PaCO2 severity subgroups. CONCLUSION: In ambulatory patients with OHS and concomitant severe OSA who were treated with NIV or CPAP, long-term NIV therapy was similar to CPAP in improving awake hypercapnia, regardless of the severity of baseline hypercapnia. Therefore, in this patient population, the decision to prescribe CPAP or NIV cannot be solely based on the presenting level of PaCO2.

Risk factors associated with pulmonary hypertension in obesity hypoventilation syndrome.

STUDY OBJECTIVES: Pulmonary hypertension (PH) is prevalent in obesity hypoventilation syndrome (OHS). However, there is a paucity of data assessing pathogenic factors associated with PH. Our objective is to assess risk factors that may be involved in the pathogenesis of PH in untreated OHS. METHODS: In a post hoc analysis of the Pickwick trial, we performed a bivariate analysis of baseline characteristics between patients with and without PH. Variables with a P value ≤ .10 were defined as potential risk factors and were grouped by theoretical pathogenic mechanisms in several adjusted models. Similar analysis was carried out for the 2 OHS phenotypes, with and without severe concomitant obstructive sleep apnea. RESULTS: Of 246 patients with OHS, 122 (50%) had echocardiographic evidence of PH defined as systolic pulmonary artery pressure ≥ 40 mm Hg. Lower levels of awake PaO2 and higher body mass index were independent risk factors in the multivariate model, with a negative and positive adjusted linear association, respectively (adjusted odds ratio 0.96; 95% confidence interval 0.93 to 0.98; P = .003 for PaO2, and 1.07; 95% confidence interval 1.03 to 1.12; P = .001 for body mass index). In separate analyses, body mass index and PaO2 were independent risk factors in the severe obstructive sleep apnea phenotype, whereas body mass index and peak in-flow velocity in early/late diastole ratio were independent risk factors in the nonsevere obstructive sleep apnea phenotype. CONCLUSIONS: This study identifies obesity per se as a major independent risk factor for PH, regardless of OHS phenotype. Therapeutic interventions targeting weight loss may play a critical role in improving PH in this patient population. CLINICAL TRIAL REGISTRATION: Registry: Clinicaltrial.gov; Name: Alternative of Treatment in Obesity Hypoventilation Syndrome; URL: https://clinicaltrials.gov/ct2/show/NCT01405976; Identifier: NCT01405976. CITATION: Masa JF, Benítez ID, Javaheri S, et al. Risk factors associated with pulmonary hypertension in obesity hypoventilation syndrome. J Clin Sleep Med. 2022;18(4):983-992.

Deconstructing Phenotypes in COPD: an Analysis of the TRACE Cohort. / Deconstruyendo los fenotipos en la EPOC: un análisis de la cohorte TRACE.

OBJECTIVES: In a clinical phenotype-based management strategy for COPD, it would be preferable to at least assign all patients to a phenotype, but to a single phenotype only. The aim of this study was to evaluate whether all patients are assigned to one and only one phenotype using the Spanish COPD guidelines (GesEPOC) and to evaluate the criteria that define these categories. METHOD: The Time-based Register and Analysis of COPD Endpoints study (TRACE; clinicaltrials.gov NCT03485690) is a prospective cohort of COPD patients attending annual visits since 2012, which collects GesEPOC phenotypes. Although the GesEPOC recommends that patients considered to be at low risk are not phenotyped, an analysis of the criteria for identifying high- and low-risk phenotypes was performed, comparing the distribution of phenotypes and the criteria applied between these 2 groups. RESULTS: The cohort included 970 patients with a confirmed diagnosis of COPD, divided into 427 (44.02%) low-risk and 543 (55.9%) high-risk patients. The most frequent phenotype was the non-exacerbator (44.9% of high-risk patients). Overall, 20.6% of low-risk patients met criteria for asthma-COPD overlap syndrome, while 9.2% of the cohort did not meet the diagnostic criteria for any phenotype, and 19.1% met the criteria for 2 phenotypes, with no differences between risk groups. CONCLUSIONS: Our data highlight some of the weaknesses of the current clinical phenotype strategy, revealing overlapping categories in some cases, and patients to whom no phenotype was assigned.

Long-term Effect of CPAP Treatment on Cardiovascular Events in Patients With Resistant Hypertension and Sleep Apnea. Data From the HIPARCO-2 Study.

BACKGROUND: There is some controversy about the effect of continuous positive airway pressure (CPAP) on the incidence of cardiovascular events (CVE). However, the incidence of CVE among patients with both obstructive sleep apnea (OSA) ans resistant hypertension (HR) has not been evaluated. Our objective was to analyze the long-term effect of CPAP treatment in patients with RH and OSA on the incidence of CVE. METHODS: Multi-center, observational and prospective study of patients with moderate-severe OSA and RH. All the patients were followed up every 3-6 months and the CVE incidence was measured. Patients adherent to CPAP (at least 4h/day) were compared with those with not adherent or those who had not been prescribed CPAP. RESULTS: Valid data were obtained from 163 patients with 64 CVE incidents. Treatment with CPAP was offered to 82%. After 58 months of follow-up, 58.3% of patients were adherent to CPAP. Patients not adherent to CPAP presented a non-significant increase in the total CVE incidence (HR:1.6; 95%CI: 0.96-2.7; p=0.07). A sensitivity analysis showed that patients not adherent to CPAP had a significant increase in the incidence of cerebrovascular events (HR: 3.1; CI95%: 1.07-15.1; p=0.041) and hypertensive crises (HR: 5.1; CI95%: 2.2-11.6; p=0.006), but the trend went in the opposite direction with respect to coronary events (HR: 0.22; CI95%: 0.05-1.02; p=0.053). CONCLUSIONS: In patients with RH and moderate-severe OSA, an uneffective treatment with CPAP showed a trend toward an increase in the incidence of CVE (particularly neurovascular events and hypertensive crises) without any changes with respect to coronary events.

Repeated Pulses of Methyl-Prednisolone in Adults Hospitalized With COVID-19 Pneumonia and Acute Respiratory Distress Syndrome: A Preliminary Before-After Study (CortiCOVID Study).

Introduction: The use of systemic corticosteroids in severely ill patients with coronavirus disease 2019 (COVID-19) is controversial. We aimed to evaluate the efficacy and safety of corticosteroid pulses in patients with COVID-19 pneumonia. Methods: A quasi-experimental study, before and after, was performed in a tertiary referral hospital, including admitted patients showing COVID-19-associated pneumonia. The standard treatment protocol included targeted COVID-19 antiviral therapy from 23rd March 2020, and additionally pulses of methylprednisolone from 30th March 2020. The primary outcome was a composite endpoint combining oro-tracheal intubation (OTI) and death within 7 days. Results: A total of 24 patients were included. Standard of care (SOC) (before intervention) was prescribed in 14 patients, while 10 received SOC plus pulses of methylprednisolone (after intervention). The median age of patients was 64.5 years and 83.3% of the patients were men. The primary composite endpoint occurred in 13 patients (92.9%) who received SOC vs. 2 patients (20%) that received pulses of methylprednisolone (odds ratio, 0.02; 95% confidence interval, 0.001 to 0.25; p = 0.019). Length of hospitalization in survivors was shorter in the corticosteroids group (median, 14.5 [8.5-21.8] days vs. 29 [23-31] days, p = 0.003). There were no differences in the development of infections between both groups. There were 3 deaths, none of them in the corticosteroids group. Conclusions: In patients with severe pneumonia due to COVID-19, the administration of methylprednisolone pulses was associated with a lower rate of OTI and/or death and a shorter hospitalization episode.

Introducción: El uso de corticosteroides sistémicos en pacientes gravemente enfermos por enfermedad coronavírica de 2019 (covid-19) es controvertido. Nuestro objetivo fue evaluar la eficacia y la seguridad de los pulsos de corticoesteroides en los pacientes con neumonía por covid-19. Métodos: Se realizó un ensayo cuasiexperimental, tipo antes y después, en un hospital terciario de referencia que incluyó a pacientes ingresados por neumonía asociada a covid-19. El protocolo de tratamiento estándar incluía un tratamiento antiviral dirigido contra el virus de la covid-19 desde el 23 de marzo de 2020 y añadió pulsos de metilprednisolona desde el 30 de marzo de 2020. El resultado primario fue un criterio combinado compuesto por la intubación orotraqueal y el fallecimiento durante los siguientes siete días. Resultados: Se incluyó un total de 24 pacientes. El protocolo de tratamiento (antes de la intervención) se prescribió en 14 pacientes, mientras que 10 recibieron el protocolo de tratamiento además de los pulsos de metilprednisolona (después de la intervención). La edad media de los pacientes fue de 64,5 años y el 83,3% de los pacientes eran hombres. El resultado combinado primario tuvo lugar en 13 pacientes (92,9%) que recibieron el protocolo de tratamiento frente a 2 pacientes (20%) que recibieron los pulsos de metilprednisolona (odds ratio = 0,02; intervalo de confianza del 95% = 0,001-0,25; p = 0,019). La duración de la hospitalización en los supervivientes fue más corta en el grupo que recibió corticoesteroides (media = 14,5 [8,5-21,8] días frente a 29 [23-31] días, p = 0,003). No hubo diferencias en el desarrollo de infecciones entre ambos grupos. Hubo tres fallecimientos, ninguno de ellos en el grupo que recibió corticoesteroides. Conclusiones: En los pacientes con neumonía grave por covid-19, la administración de pulsos de metilprednisolona se asoció a unas tasas menores de intubación orotraqueal y/o muerte y a episodios de hospitalización más cortos.

Predictors of Single Bronchodilation Treatment Response for COPD: An Observational Study with the Trace Database Cohort.

Chronic obstructive pulmonary disease (COPD) patients constitute a heterogeneous population in terms of treatment response. Our objective was to identify possible predictive factors of response to treatment with single bronchodilation monotherapy in patients diagnosed with COPD. The Time-based Register and Analysis of COPD Endpoints (TRACE; clinicaltrials.gov NCT03485690) is a prospective cohort of COPD patients who have been attending annual visits since 2012. Patients who were kept on a single bronchodilator during the first year of follow-up were selected. The responders were defined according to all of the following variables: any improvement in morning post-dose forced expiratory volume in 1 s or deterioration <100 mL, no change or improvement in dyspnea score, and no occurrence of exacerbations. Significant and plausible variables were analyzed using a proportional hazard Cox regression for single bronchodilator responders. We analyzed 764 cases, of whom 128 (16.8%) were receiving monotherapy with one bronchodilator. Of these, 85 patients (66.4%) were responders. Factors affecting responder status were: female gender (hazard ratio (HR) 0.276; 95% confidence interval (CI) 0.089-0.858), dyslipidemia (HR 0.436; 95%CI 0.202-0.939), not performing regular exercise (HR 0.523; 95%CI 0.254-1.076), active smoking (HR 0.413; 95%CI 0.186-0.920), and treatment adherence (HR 2.527; 95%CI 1.271-5.027). The factors associated with a single bronchodilation response are mainly non-pharmacological interventions and comorbidities.

Long-term Noninvasive Ventilation in Obesity Hypoventilation Syndrome Without Severe OSA: The Pickwick Randomized Controlled Trial.

BACKGROUND: Noninvasive ventilation (NIV) is an effective form of treatment in obesity hypoventilation syndrome (OHS) with severe OSA. However, there is paucity of evidence in patients with OHS without severe OSA phenotype. RESEARCH QUESTION: Is NIV effective in OHS without severe OSA phenotype? STUDY DESIGN AND METHODS: In this multicenter, open-label parallel group clinical trial performed at 16 sites in Spain, we randomly assigned 98 stable ambulatory patients with untreated OHS and apnea-hypopnea index < 30 events/h (ie, no severe OSA) to NIV or lifestyle modification (control group) using simple randomization through an electronic database. The primary end point was hospitalization days per year. Secondary end points included other hospital resource utilization, incident cardiovascular events, mortality, respiratory functional tests, BP, quality of life, sleepiness, and other clinical symptoms. Both investigators and patients were aware of the treatment allocation; however, treating physicians from the routine care team were not aware of patients' enrollment in the clinical trial. The study was stopped early in its eighth year because of difficulty identifying patients with OHS without severe OSA. The analysis was performed according to intention-to-treat and per-protocol principles and by adherence subgroups. RESULTS: Forty-nine patients in the NIV group and 49 in the control group were randomized, and 48 patients in each group were analyzed. During a median follow-up of 4.98 years (interquartile range, 2.98-6.62), the mean hospitalization days per year ± SD was 2.60 ± 5.31 in the control group and 2.71 ± 4.52 in the NIV group (adjusted rate ratio, 1.07; 95% CI, 0.44-2.59; P = .882). NIV therapy, in contrast with the control group, produced significant longitudinal improvement in Paco2, pH, bicarbonate, quality of life (Medical Outcome Survey Short Form 36 physical component), and daytime sleepiness. Moreover, per-protocol analysis showed a statistically significant difference for the time until the first ED visit favoring NIV. In the subgroup with high NIV adherence, the time until the first event of hospital admission, ED visit, and mortality was longer than in the low adherence subgroup. Adverse events were similar between arms. INTERPRETATION: In stable ambulatory patients with OHS without severe OSA, NIV and lifestyle modification had similar long-term hospitalization days per year. A more intensive program aimed at improving NIV adherence may lead to better outcomes. Larger studies are necessary to better determine the long-term benefit of NIV in this subgroup of OHS. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT01405976; URL: www.clinicaltrials.gov.

Experimental Approach to Examine Leptin Signaling in the Carotid Bodies and its Effects on Control of Breathing.

An adipocyte-produced hormone leptin is a potent respiratory stimulant, which may play an important role in defending respiratory function in obesity. The carotid bodies (CB), a key organ of peripheral hypoxic sensitivity, express the long functional isoform of leptin receptor (LepRb) but the role of leptin signaling in control of breathing has not been fully elucidated. We examined the hypoxic ventilatory response (HVR) (1) in C57BL/6J mice before and after leptin infusion at baseline and after CB denervation; (2) in LepRb-deficient obese db/db mice at baseline and after LepRb overexpression in CBs. In C57BL/6J mice, leptin increased HVR and effects of leptin on HVR were abolished by CB denervation. In db/db mice, LepRb expression in CB augmented the HVR. Therefore, we conclude that leptin acts in CB to augment responses to hypoxia.

Relationship between the endothelial dysfunction and the expression of the ß1-subunit of BK channels in a non-hypertensive sleep apnea group.

STUDY OBJECTIVES: Vascular damage must be diagnosed early in patients with hypertension. In this regard, endothelial dysfunction (ED) is an early sign of vascular disease and a predictor of cardiovascular diseases. In obstructive sleep apnea (OSA), intermittent hypoxia triggers ED, but mechanisms are not clear. In this context, it has been described that BK channels regulates arterial tone and that chronic and intermittent hypoxia downregulates the expression of the BK channel ß1-subunit facilitating vasoconstriction. Thus, we investigated the relationship among hypoxemia, ED, and mRNA expression of the ß1-subunit in patients with severe OSA. We aimed to assess (1) ED in non-hypertensive patients with OSA using laser-Doppler flowmetry, (2) BK ß1-subunit mRNA expression, and (3) the impact of continuous positive airway pressure (CPAP) treatment on ED and ß1-subunit regulation. METHODS: OSA patients underwent 24-hour blood pressure monitoring to exclude hypertension. Laser-Doppler flowmetry was performed to assess ED, and ß1-subunit mRNA expression was evaluated using a blood test of peripheral blood leukocytes at baseline and after 3 months of CPAP treatment. RESULTS: In normotensive patients with OSA, endothelial function correlated with the severity of OSA. CPAP improved endothelial function in normotensive OSA patients and the speed of the arterial response was significantly correlated with ß1-subunit mRNA expression. ß1-subunit mRNA expression at baseline correlated inversely with its change after CPAP. CONCLUSIONS: Sleep apnea is related to ED in normotensive patients with OSA. CPAP therapy improves endothelial function and regulates ß1-subunit mRNA expression.

Effect of continuous positive airway pressure in patients with true refractory hypertension and sleep apnea: a post-hoc intention-to-treat analysis of the HIPARCO randomized clinical trial.

RATIONALE: Continuous positive airway pressure (CPAP) can significantly reduce blood pressure (BP) levels in patients with resistant hypertension and sleep apnea (OSA); however, the effect on patients with refractory hypertension (RfH) is not known. This study seeks to evaluate the effect of CPAP treatment on BP levels in patients with OSA and RfH, compared with those with OSA and resistant hypertension. METHODS: Post-hoc analysis of the HIPARCO randomized clinical trial on the effect of CPAP treatment on BP levels in patients with resistant hypertension. Those patients with uncontrolled 24-h ambulatory BP monitoring readings (>130 and/or >80 mmHg) in SBP or DBP were considered to have resistant hypertension (if they were taking three or four antihypertensive drugs) or RfH (if they were taking at least five drugs). OSA patients were randomized to receive CPAP or usual care for 3 months. They underwent a second 24-h ambulatory BP monitoring study to establish the effect of CPAP treatment on BP levels in both groups. RESULTS: A total of 98 patients were randomized to CPAP (19 RfH/79 resistant hypertension) and 96 to usual care (21 RfH/75 resistant hypertension). BP readings dropped more marked in patients with RfH than resistant hypertension, in both 24-h SBP (-9 vs. -1.6 mmHg, P = 0.021) and 24-h DBP (-7.3 vs. -2.3 mmHg, P = 0.074), especially at night (-11.3 vs. -3.8, P = 0.121 and -8.8 vs. -2.2, P = 0.054) respectively. Adjusted difference between groups was statistically significant in 24-h SBP levels (-7.4 mmHg, P = 0.021). CONCLUSION: CPAP lowers BP levels in both resistant hypertension and RfH patients although the degree of this reduction is higher in those with RfH especially during the night.

Factors associated with the changes from a resistant to a refractory phenotype in hypertensive patients: a Pragmatic Longitudinal Study.

Refractory hypertension (RfH) is defined as a lack of blood pressure control despite the administration of at least 5 anti-hypertensive drugs. The factors associated with its natural history are unknown. This study aimed to evaluate both the incidence of RfH in an cohort of patients with resistant hypertension (RH) and the factors involved in that progression. This was an observational prospective multicenter study (24 centers) with 172 patients with confirmed RH (24-h ABPM) who underwent a further 24 h ABPM study at the end of the follow-up. Prospective information was obtained from all patients in their corresponding Hypertension Units via a standard clinical protocol, and they all underwent a sleep study. Thirty patients were diagnosed with RfH (17.4%) after a mean follow-up of 57 months, despite the prescription of a greater number of long-acting thiazide-like diuretics and mineralocorticoid receptor antagonists. The factors associated with progression to RfH were: a longer period since the diagnosis of RH (OR: 1.06, 95% CI: 1.01-1.1, p = 0.007); the HbA1c concentration (OR: 1.42, 95% CI: 1.42-1.8; p = 0.005); the initial heart rate (OR: 1.05, 95% CI: 1.01-1.09, p = 0.004); and poor adherence to continuous positive airway pressure (CPAP) in cases of obstructive sleep apnea (OR: 3.36, 95% CI: 1.47-7.7, p = 0.004). In conclusion, a considerable percentage of patients evolved from the RH to the RfH phenotype despite changes in their treatment. Some easily measurable variables, such as heart rate, the time since the diagnosis, the HbA1c level, and the presence of untreated obstructive sleep apnea (or poor adherence to CPAP) have been demonstrated to be prognostic factors in the progression to RfH.

Sleep-disordered breathing in C57BL/6J mice with diet-induced obesity.

Obesity leads to sleep-disordered breathing (SDB) manifested by recurrent upper airway obstructions termed obstructive sleep apnea (OSA) and carbon dioxide retention due to hypoventilation. The objective of this work was to characterize breathing during sleep in C57BL6/J mice with diet-induced obesity (DIO). Arterial blood gas was measured in nine obese and nine lean mice during wakefulness. Nine male mice with DIO and six lean male C57BL/6J mice were head mounted with electroencephalogram (EEG) and electromyogram (EMG) electrodes. Sleep recordings were performed in the whole body plethysmography chamber; upper airway obstruction was characterized by the presence of inspiratory flow limitation in which airflow plateaus with increases in inspiratory effort. Obese mice showed significantly lower pH and higher partial pressure of arterial CO2 (PaCO2) in arterial blood gas compared to lean mice, 7.35 ± 0.04 versus 7.46 ± 0.06 (p < 0.001) and 38 ± 8 mm Hg versus 30 ± 5 mm Hg (p < 0.001). Obese mice had similar levels of minute ventilation to lean mice during sleep and wakefulness, despite higher body weight and temperature, indicating an increase in the metabolic rate and hypoventilation. Obese mice also showed baseline hypoxemia with decreased mean oxyhemoglobin saturation across sleep/wake states. Obese mice had a higher prevalence of flow-limited breathing compared to lean mice during sleep. However, the oxygen desaturation index in lean and obese mice did not differ. We conclude that DIO in mice leads to hypoventilation. Obesity also increases the frequency of inspiratory limited breaths, but it does not translate into progression of OSA.

Beyond Resistant Hypertension.

Obstructive sleep apnea (OSA) is an independent cause of resistant hypertension (RH) but its association with refractory hypertension (RfH), a recently described form of severe hypertension, has not yet been investigated. This study seeks to analyze the association between the presence and severity of OSA/OSA syndrome with RfH and to compare it with a group of patients with OSA/OSA syndrome and RH. We conducted a multicenter, cross-sectional study of consecutive patients diagnosed with RH by means of 24-hour ambulatory blood pressure monitoring. Those patients with blood pressure levels ≥130/80 mm Hg, despite taking at least 5 antihypertensive drugs, were considered to have true RfH. All patients underwent a sleep study and completed a detailed clinical history related to OSA, current medication, and cardiovascular diseases. Overall, 229 patients were included (mean age, 58.3 years; 63% male), of whom 42 (18.3%) satisfied the criteria for RfH. Compared with those with RH, patients with RfH had a higher cardiovascular risk profile, higher blood pressure measurements, and a 2-fold greater risk of having both severe OSA (odds ratio, 2.1, with a prevalence of apnea-hypopnea index ≥15, 95.2% and apnea-hypopnea index ≥30, 64.3%) and OSA syndrome (apnea-hypopnea index ≥5+Epworth Sleepiness Scale >10; odds ratio, 1.9; 52.4% versus 37.3%; P=0.023), as well as higher OSA severity (apnea-hypopnea index, 41.8 versus 33.8 events/h; P=0.026). Patients with RfH had an even greater prevalence and severity of OSA and OSA syndrome than RH patients, highlighting the need to identify these patients to refer them to sleep units on a preferential basis.