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This document summarizes suggestions of the central sleep apnea (CSA) Technical Expert Panel working group. This paper shares our vision for bringing the right device to the right patient at the right time. For patients with CSA, current coverage criteria do not align with guideline treatment recommendations. For example, CPAP and oxygen therapy are recommended but not covered for CSA. On the other hand, bilevel positive airway pressure (BPAP) without a backup rate may be a covered therapy for OSA, but it may worsen CSA. Narrow coverage criteria that require near elimination of obstructive breathing events on CPAP or BPAP in the spontaneous mode, even if at poorly tolerated pressure levels, may preclude therapy with BPAP with backup rate or adaptive servoventilation, even when those devices provide demonstrably better therapy. CSA is a dynamic disorder that may require different treatments over time, sometimes switching from one device to another; an example is switching from BPAP with backup rate to an adaptive servoventilation with automatic end-expiratory pressure adjustments, which may not be covered. To address these challenges, we suggest several changes to the coverage determinations, including: (1) a single simplified initial and continuing coverage definition of CSA that aligns with OSA; (2) removal of hypoventilation terminology from coverage criteria for CSA; (3) all effective therapies for CSA should be covered, including oxygen and all PAP devices with or without backup rates or servo-mechanisms; and (4) patients shown to have a suboptimal response to one PAP device should be allowed to add oxygen or change to another PAP device with different capabilities if shown to be effective with testing.

The current national coverage determinations (NCDs) for noninvasive ventilation for patients with thoracic restrictive disorders, COPD, and hypoventilation syndromes were formulated in 1998. New original research, updated formal practice guidelines, and current consensus expert opinion have accrued that are in conflict with the existing NCDs. Some inconsistencies in the NCDs have been noted, and the diagnostic and therapeutic technology has also advanced in the last quarter century. Thus, these and related NCDs relevant to bilevel positive airway pressure for the treatment of OSA and central sleep apnea need to be updated to ensure the optimal health of patients with these disorders. To that end, the American College of Chest Physicians organized a multisociety (American Thoracic Society, American Academy of Sleep Medicine, and American Association for Respiratory Care) effort to engage experts in the field to: (1) identify current barriers to optimal care; (2) highlight compelling scientific evidence that would justify changes from current policies incorporating best evidence and practice; and (3) propose suggestions that would form the basis for a revised NCD in each of these 5 areas (thoracic restrictive disorders, COPD, hypoventilation syndromes, OSA, and central sleep apnea). The expert panel met during a 2-day virtual summit in October 2020 and subsequently crafted written documents designed to achieve provision of "the right device to the right patient at the right time." These documents have been endorsed by the participating societies following peer review and publication in CHEST and will be used to inform efforts to revise the current NCDs.

Background Noninvasive ventilation (NIV) is standard of care for chronic hypercapnic respiratory failure, but indications, devices, and ventilatory modes are in constant evolution. Research Question To describe changes in prevalence and indications for NIV over a 15-year period; to provide a comprehensive report of characteristics of the population treated (age, comorbidities, and anthropometric data), mode of implementation and follow-up, devices, modes and settings used, physiological data, compliance, and data from ventilator software. Study Design and Methods Cross-sectional observational study designed to include all subjects under NIV followed by all structures involved in NIV in the Cantons of Geneva and Vaud (1,288,378 inhabitants). Results A total of 489 patients under NIV were included. Prevalence increased 2.5-fold since 2000 reaching 38 per 100,000 inhabitants. Median age was 71 years, with 31% being > 75 years of age. Patients had been under NIV for a median of 39 months and had an average of 3 ± 1.8 comorbidities; 55% were obese. COPD (including overlap syndrome) was the most important patient group, followed by obesity hypoventilation syndrome (OHS) (26%). Daytime Pa co 2 was most often normalized. Adherence to treatment was satisfactory, with 8% only using their device Interpretation Use of NIV is increasing rapidly in this area, and the population treated is aging, comorbid, and frequently obese. COPD is presently the leading indication followed by OHS. Trial Registry ClinicalTrials.gov; No.: NCT04054570; URL: www.clinicaltrials.gov

The prevalence of obesity is rising worldwide. Adipose tissue exerts anatomic and physiologic effects with significant implications for critical illness. Changes in respiratory mechanics cause expiratory flow limitation, atelectasis, and ventilation/perfusion mismatch with resultant hypoxemia. Altered work of breathing and obesity hypoventilation syndrome may cause hypercapnia. Challenging mask ventilation and peri-intubation hypoxemia may complicate intubation. Patients with obesity are at increased risk of acute respiratory distress syndrome and should receive lung-protective ventilation based on predicted body weight. Increased positive end expiratory pressure (PEEP), coupled with appropriate patient positioning, may overcome the alveolar decruitment and intrinsic PEEP caused by elevated baseline pleural pressure, though evidence is insufficient regarding the impact of high PEEP strategies on outcomes. Venovenous extracorporeal membrane oxygenation may be safely performed in patients with obesity. Fluid management should account for increased prevalence of chronic heart and kidney disease, expanded blood volume, and elevated acute kidney injury risk. Medication pharmacodynamics and pharmacokinetics may be altered by hydrophobic drug distribution to adipose depots and comorbid liver or kidney disease. Obesity is associated with increased risk of venous thromboembolism and infection; appropriate dosing of prophylactic anti-coagulation and early removal of indwelling catheters may decrease these risks. Obesity is associated with improved critical illness survival in some studies. It is unclear whether this reflects a protective effect or limitations inherent to observational research. Obesity is associated with increased risk of intubation and death in SARS-CoV-2 infection. Ongoing molecular studies of adipose tissue may deepen understanding of how obesity impacts critical illness pathophysiology.

When and how do I qualify inpatients with acute on chronic hypercapnic respiratory failure for home noninvasive positive-pressure ventilation at the time of discharge? A 44-year-old woman with morbid obesity (BMI, 48) was brought to the hospital by her boyfriend for 1 day of confusion and reduced alertness. She had a history of chronic dyspnea on exertion and 10-pack-years of smoking. She also had history of well-treated diabetes and hypertension. In the ER, she was found to be somnolent but arousable and following commands appropriately. Her oxygen saturation was 86% on room air, and arterial blood gases indicated a pH of 7.16 with a Paco2 of 87 mm Hg, a Pao2 of 60 mm Hg, and a bicarbonate of 42 mEq/L. Chest radiograph showed mild pulmonary vascular congestion. She was started on continuous bilevel positive airway pressure and medical therapy, with clinical improvement.

Although noninvasive ventilation (NIV) has been used since the 1950s in the polio epidemic, the development of modern bilevel positive airway pressure (BPAP) devices did not become a reality until the 1990s. Over the past 25 years, BPAP technology options have increased exponentially. The number of patients receiving this treatment both in the acute setting and at home is growing steadily. However, a knowledge gap exists in the way the settings on these devices are adjusted to achieve synchrony and match the patient's unique physiology of respiratory failure. This issue is further complicated by differences in pressure and flow dynamic settings among different types of NIV devices available for inpatient and home care.

TOPIC: Chest Infections TYPE: Original Investigations PURPOSE: The recent two waves of the pandemic have caused over 127,000 deaths in the UK, with over 4.4 million cases and estimated global mortality of approximately 3 million when writing this abstract. Patients hospitalised with COVID-19 pneumonia have severe hypoxic respiratory failure, and it can be challenging to maintain adequate oxygenation with traditional oxygen supplementation. Continuous Positive Airway Pressure (CPAP) was used to avoid mechanical ventilation and rationalise oxygen stocks. CPAP is beneficial in studies globally. We studied the outcomes of the survivors of COVID 19 pneumonia treated exclusively with CPAP who belonged to the Not for ICU group, admitted exclusively to the ward-based CPAP unit. METHODS: Retrospective data were collected on the survivors of patients admitted to a ward-based CPAP in Suspected or confirmed COVID-19 with pneumonitis and type 1 Respiratory failure. Patients admitted for BIPAP were excluded. Patients on CPAP for OSA or Obesity Hypoventilation syndrome who required being in the unit for infection control purposes were also excluded. Data collected on basic demographics and specific information like comorbidities, status length of stay, CPAP duration, discharge prescription of oxygen were collected and analysed. RESULTS: 28 patients were identified who received CPAP only during both the first and second wave (March to July 2021 and January to March 2021) of the pandemic. 17 Males and 11 females, 60% and 40% respectively, received CPAP only—the average age was 63.5 years, range 37 to 86 years. Twenty-six out of survivors of CPAP only treatment group 28 are alive, at 30 days 60 days and 26 were alive at 90 days. The mean length of stay of this cohort was 23 days due to rehabilitation requirements. Further, twenty-seven out of twenty-eight patients (96% ) were COVID PCR positive, and one patient was COVID PCR negative but radiology consistent with COVID pneumonitis. Nine patients (31.2%) were discharged on home oxygen;4 of them had a respiratory morbidity -2 patients with ILD, two patients with COPD. At 90 days, 4 of these nine patients discharged on home oxygen were still on oxygen Duration CPAP ranged from and 3 to 14 days with an average of 6.33 days. Two patients were on CPAP at discharge due to a new diagnosis of Obesity hypoventilation /OSA, and 5 of them were on CPAP for OSA at admission. The most common comorbidities among this cohort were Hypertension 9/28, Diabetes mellitus 7/28, Asthma 4/28 and COPD 3 /28 patients CONCLUSIONS: Patients treated who received exclusive ward-based CPAP due to being not for ICU level of care had a good 60-day 90-day survival. Up to a third (31.2%) were still requiring oxygen at the time of discharge, indicating a prolonged recovery phase of the respiratory failure.15% still on oxygen at 90 days. CLINICAL IMPLICATIONS: CPAP for COVID pneumonia has favourable outcome even at 60 and 90 days post CPAP, with a third of patients requiring oxygen at discharge. DISCLOSURES: No relevant relationships by Wee Teck Lim, source=Web Response No relevant relationships by Farah Asyikin Mohamad Nasir, source=Web Response No relevant relationships by Ernest Okpo, source=Web Response No relevant relationships by Aravind Ponnuswamy, source=Web Response No relevant relationships by Tariq Trussell, source=Web Response

Background Surgical patients with OSA are at increased risk for perioperative complications. Postoperative supplemental oxygen is commonly used, but it may contribute to respiratory depression in patients with OSA receiving opioids. The objective of the study is to investigate the effect of postoperative supplemental oxygen on arterial oxygen saturation (Sao 2 ), sleep respiratory events, and CO 2 level in patients with untreated OSA. Methods Consented patients with an apnea hypopnea index (AHI) > 5 events per hour on a preoperative polysomnography were randomized (1:1) to oxygen (O 2 group) or no oxygen (control group). The O 2 group received oxygen at 3 L/min via nasal prongs for three postoperative nights. The primary outcomes were polysomnographic parameters measuring Sao 2 , sleep respiratory events, and Pco 2 measured by transcutaneous CO 2 monitor (P tc CO 2 ) on nights 1 through 3. The intention-to-treat and per protocol analysis were completed. Results There were 123 patients randomized (O 2 group: n = 62; control group: n = 61). On night 3, the O 2 vs control group had a higher average Sao 2 (95.2% ± 3% vs 91.4% ± 4%, respectively; P P 2 group had a decreased AHI (median, 8.0; 25th-75th percentile, 2.1-19.9 vs median, 15.6; 25th-75th percentile, 9.5-45.8, respectively; P = .016), hypopnea index ( P P = .026) and a shortened longest apnea hypopnea duration ( P = .002). Although time percentage with P tc CO 2 ≥ 55 mm Hg ≥ 10% on postoperative night 1, 2, or 3 was found in 11.4% patients, there was no difference in P tc CO 2 between the groups. Conclusions Postoperative supplemental oxygen was found to improve oxygenation and decrease the AHI without increasing the duration of apnea-hypopnea event or P tc CO 2 level. A small number of patients had significant CO 2 retention while receiving supplemental oxygen. Trial Registry ClinicalTrials.gov; No.: NCT01552304; URL: www.clinicaltrials.gov

Noninvasive ventilation (NIV) is standard of care for chronic hypercapnic respiratory failure, but indications, devices, and ventilatory modes are in constant evolution.To describe changes in prevalence and indications for NIV over a 15-year period; to provide a comprehensive report of characteristics of the population treated (age, comorbidities, and anthropometric data), mode of implementation and follow-up, devices, modes and settings used, physiological data, compliance, and data from ventilator software.Cross-sectional observational study designed to include all subjects under NIV followed by all structures involved in NIV in the Cantons of Geneva and Vaud (1,288,378 inhabitants).A total of 489 patients under NIV were included. Prevalence increased 2.5-fold since 2000 reaching 38 per 100,000 inhabitants. Median age was 71 years, with 31% being 75 years of age. Patients had been under NIV for a median of 39 months and had an average of 3 ± 1.8 comorbidities; 55% were obese. COPD (including overlap syndrome) was the most important patient group, followed by obesity hypoventilation syndrome (OHS) (26%). Daytime PacoUse of NIV is increasing rapidly in this area, and the population treated is aging, comorbid, and frequently obese. COPD is presently the leading indication followed by OHS.ClinicalTrials.gov; No.: NCT04054570; URL: www.clinicaltrials.gov.

Obesity hypoventilation syndrome is becoming an increasingly encountered condition both in respiratory outpatient clinics and in hospitalized patients. The health consequences and social disadvantages of obesity hypoventilation syndrome are significant. Unfortunately, the diagnosis and institution of appropriate therapy is commonly delayed when the syndrome is not recognized or misdiagnosed. Positive airway pressure therapy remains the mainstay of treatment and is effective in controlling sleep-disordered breathing and improving awake blood gases in the majority of individuals. Evidence supporting one mode of therapy over another is limited. Both continuous and bilevel therapy modes can successfully improve daytime gas exchange, with adherence to therapy an important modifiable factor in the response to treatment. Despite adherence to therapy, these individuals continue to experience excess mortality primarily due to cardiovascular events compared with those with eucapnic sleep apnea using CPAP. This difference likely arises from ongoing systemic inflammation secondary to the morbidly obese state. The need for a comprehensive approach to managing nutrition, weight, and physical activity in addition to reversal of sleep-disordered breathing is now widely recognized. Future studies need to evaluate the impact of a more aggressive and comprehensive treatment plan beyond managing sleep-disordered breathing. The impact of early identification and treatment of sleep-disordered breathing on the development and reversal of cardiometabolic dysfunction also requires further attention.

OSA is a common yet underdiagnosed disorder encountered in everyday practice. The disease is a unique physiologic stressor that contributes to the development or progression of many other disorders, particularly cardiovascular conditions. The pulmonary circulation is specifically affected by the intermittent hypoxic apneas associated with OSA. The general consensus has been that OSA is associated with pulmonary hypertension (PH), but only in a minority of OSA patients and generally of a mild degree. Consequently, there has been no sense of urgency to screen for either condition when evaluating the other. In this review, we explore available evidence describing the interaction between OSA and PH and seek to better understand underlying pathophysiology. We describe certain groups of patients who have a particular preponderance of OSA and PH. Failure to recognize the mutual additive effects of these disorders can lead to suboptimal patient outcomes. Among patients with PH and OSA, CPAP, the mainstay treatment for OSA, may ameliorate pulmonary pressure elevations, but has not been studied adequately. Conversely, among patients with OSA, PH significantly limits functional capacity and potentially shortens survival; yet, there is no routine screening for PH in patients with OSA. We think it is time to study the interaction between OSA and PH more carefully to identify high-risk subgroups. These would be screened for the presence of combined disorders, facilitating earlier institution of therapy and improving outcomes.

Although noninvasive ventilation (NIV) has been used since the 1950s in the polio epidemic, the development of modern bilevel positive airway pressure (BPAP) devices did not become a reality until the 1990s. Over the past 25 years, BPAP technology options have increased exponentially. The number of patients receiving this treatment both in the acute setting and at home is growing steadily. However, a knowledge gap exists in the way the settings on these devices are adjusted to achieve synchrony and match the patient's unique physiology of respiratory failure. This issue is further complicated by differences in pressure and flow dynamic settings among different types of NIV devices available for inpatient and home care.

Background: Unintentional leaks, patient-ventilatory asynchrony, and obstructive or central events (either residual or induced by noninvasive positive pressure ventilation [NPPV]) occur in patients treated with NPPV, but the impact of ventilator settings on these disturbances has been little explored. The objective of this study was to investigate the impact of backup respiratory rate (BURR) settings on the efficacy of ventilation, sleep structure, subjective sleep quality, and respiratory events in a group of patients with obesity hypoventilation syndrome (OHS). Methods: Ten stable patients with OHS treated with long-term nocturnal NPPV underwent polysomnographic recordings and transcutaneous capnography on 3 consecutive nights with three different settings for BURR in random order: spontaneous (S) mode, low BURR, and high BURR. No other ventilator parameter was modified. Results: The S mode was associated with the occurrence of a highly significant increase in respiratory events, mainly of central and mixed origin, when compared with both spontaneous/timed (S/T) modes. Accordingly, the oxygen desaturation index was significantly higher in the S mode than in either of the S/T modes. The results of nocturnal transcutaneous PCO 2 (PtcCO 2 ) (mean value and time spent with PtcCO 2 >50 mm Hg) were similar over the three consecutive nocturnal recordings. The quality of sleep was perceived as slightly better, and the number of perceived arousals as lower with the low- vs high-BURR (S/T) mode. Conclusions: In a homogenous group of patients treated with long-term NPPV for obesity-hypoventilation, changing BURR from an S/T mode with a high or low BURR to an S mode was associated with the occurrence of a highly significant increase in respiratory events, of mainly central and mixed origin. Trial registry: ClinicalTrials.gov; No.: NCT01130090; URL: www.clinicaltrials.gov. © 2013 American College of Chest Physicians.

Objective Open studies suggest that treatment of obesity hypoventilation syndrome (OHS) by noninvasive ventilation (NIV) restores sleep quality and daytime vigilance and reduces cardiovascular morbidity. However, to our knowledge no randomized controlled trial (RCT) comparing NIV to conservative measures is available in the field. The goal of this study was to assess in patients with OHS, during an RCT, effects of 1-month NIV compared with lifestyle counseling on blood gas measurements, sleep quality, vigilance, and cardiovascular, metabolic, and inflammatory parameters. Methods Thirty-five patients in whom OHS was newly diagnosed were randomized either to the NIV group or the control group represented by lifestyle counseling. Assessments included blood gas levels, subjective daytime sleepiness, metabolic parameters, inflammatory (hsCRP, leptin, regulated upon activation normal T-cell express and secreted [RANTES], monocyte chemoattractant protein-1, IL-6, IL-8, tumor necrosis factor-α, resistin) and antiinflammatory (adiponectin, IL-1-RA) cytokines, sleep studies, endothelial function (reactive hyperemia measured by peripheral arterial tonometry [RH-PAT]), and arterial stiffness. Results Despite randomization, NIV group patients (n = 18) were older (58 ± 11 years vs 54 ± 6 years) with a higher baseline Pa co 2 (47.9 ± 4.2 mm Hg vs 45.2 ± 3 mm Hg). In intention-to-treat analysis, compared with control group, NIV treatment significantly reduced daytime Pa co 2 (difference between treatments: −3.5 mm Hg; 95% CI, −6.2 to −0.8) and apnea-hypopnea index (−40.3/h; 95% CI, −62.4 to −18.2). Sleep architecture was restored, although nonrespiratory microarousals increased (+9.4/h of sleep; 95% CI, 1.9-16.9), and daytime sleepiness was not completely normalized. Despite a dramatic improvement in sleep hypoxemia, glucidic and lipidic metabolism parameters as well as cytokine profiles did not vary significantly. Accordingly, neither RH-PAT (+0.02; 95% CI, −0.24 to 0.29) nor arterial stiffness (+0.22 m/s; 95% CI, −1.47 to 1.92) improved. Conclusions One month of NIV treatment, although improving sleep and blood gas measurements dramatically, did not change inflammatory, metabolic, and cardiovascular markers. Trial registry ClinicalTrials.gov ; No.: NCT00603096 ; URL: www.clinicaltrials.gov

Background It is unknown whether oxygen therapy causes worsening hypercapnia in patients with obesity-associated hypoventilation (OAH), similar to the response observed in COPD. The objectives of this study were to investigate whether breathing 100% oxygen results in an increase in hypercapnia in patients with OAH and the mechanisms of any effect. Methods In this double-blind, randomized, controlled, crossover trial, 24 outpatients with newly diagnosed OAH inhaled 100% oxygen or room air for 20 min on 2 separate days. Transcutaneous CO 2 tension (Ptco 2 ), minute ventilation, and volume of dead space to tidal volume ratio were measured at baseline and at 20 min. A mixed linear model was used to determine differences between the two treatments. Results The study was terminated in three subjects breathing 100% oxygen due to a Ptco 2 increase ≥ 10 mm Hg, which occurred after 10:35, 13:20, and 15:51 min. Ptco 2 increased by 5.0 mm Hg (95% CI, 3.1–6.8; P P = .03), and volume of dead space to tidal volume ratio increased by 0.067 (95% CI, 0.035–0.10; P Conclusions Breathing 100% oxygen causes worsening hypercapnia in stable patients with OAH. Trial registry Australia New Zealand Clinical Trials Registry; No.: ACTRN 12608000592347; URL: www.anzctr.org.au.

The pathogenesis of daytime hypercapnia (Paco2or= 45 mm Hg) may be directly linked to the existence of obstructive sleep apnea syndrome (OSAS) per se, although only some patients with OSAS exhibit daytime hypercapnia.To investigate the prevalence of daytime hypercapnia in patients with OSAS; the association of daytime hypercapnia and obesity, obstructive airflow limitation, restrictive lung impairment, and severity of sleep apnea; and the response to continuous positive airway pressure (CPAP) therapy in a subset of subjects.The study involved 1,227 patients with OSAS who visited a sleep clinic and were examined using polysomnography. As for the response to CPAP therapy, the patients were considered good responders if their daytime Paco2 decreasedor= 5 mm Hg and poor responders if it decreased5 mm Hg.Fourteen percent (168 of 1,227 patients) exhibited daytime hypercapnia. These patients had significantly higher body mass index (BMI) and apnea-hypopnea index (AHI) values compared with normocapnic patients, while percentage of predicted vital capacity (%VC) and FEV(1)/FVC ratio did not differ between the two groups. Logistic regression analysis showed that only AHI was a predictor of daytime hypercapnia (p0.0001), while BMI (p = 0.051) and %VC (p = 0.062) were borderline predictors of daytime hypercapnia. Daytime hypercapnia was corrected in some patients (51%, 19 of 37 patients) with severe OSAS after 3 months of CPAP therapy.The pathogenesis of daytime hypercapnia may be directly linked to sleep apnea in a subgroup of patients with OSAS.

Background Polysomnography findings between matched groups with obstructive sleep apnea (OSA) and OSA plus obesity-hypoventilation syndrome (OHS) before and after continuous positive airway pressure (CPAP), particularly in the extremely severe obese (body mass index [BMI] ≥ 50 kg/m 2 ), are unclear. Design Prospective study of subjects (BMI ≥ 50 kg/m 2 ) undergoing diagnostic polysomnography. Subjects with an apnea-hypopnea index (AHI) ≥ 15/h underwent a second polysomnography with CPAP. The effect of 1 night of CPAP on sleep architecture, AHI, arousal indexes, and nocturnal oxygenation was assessed. OHS was defined as those subjects with obesity, Pa co 2 > 45 mm Hg, and Pa o 2 Results Twenty-three subjects with moderate-to-severe OSA and 23 subjects with moderate-to-severe OSA plus OHS underwent a 1-night trial of CPAP. Both groups were matched for spirometry, BMI, and AHI, but oxygen desaturation was worse in the OSA-plus-OHS group. CPAP significantly improved rapid eye movement (REM) duration (p o 2 ) 20% of TST with Sp o 2 Conclusions Extremely severe obese subjects (BMI ≥ 50 kg/m 2 ) with moderate-to-severe OSA plus OHS exhibit severe oxygen desaturation but similar severities of AHI, arousal indexes, and sleep architecture abnormalities when compared to matched subjects without OHS. CPAP significantly improves AHI, REM duration, arousal indexes, and nocturnal oxygen desaturation. Some subjects with OHS continued to have nocturnal desaturation despite the control of upper airway obstruction; other mechanisms may contribute. Further long-term studies assessing the comparative role of CPAP and bilevel ventilatory support in such subjects with OHS is warranted.

Background The obesity-hypoventilation syndrome (OHS), commonly defined as a combination of obesity and diurnal hypercapnia, is efficiently treated using nasal positive pressure ventilation (NPPV). The present study aimed to determine whether nocturnal polysomnography allows detection of respiratory disturbances occurring in patients with OHS treated with NPPV that may interfere with the quality of sleep and of ventilatory support, and are not detected by nocturnal pulse oximetry and capnography. Methods Twenty OHS patients in stable clinical condition treated by NPPV for at least 3 months with a bilevel pressure support ventilator were studied. All patients underwent single-night polysomnography under NPPV including transcutaneous measurement of P co 2 (TcP co 2 ). Four types of respiratory events were defined and quantified: patient/ventilator desynchronization, periodic breathing (PB), autotriggering, and apnea-hypopneas. Results Eleven patients (55%) exhibited desynchronization occurring mostly in slow-wave sleep and rapid eye movement sleep and associated with arousals but not inducing significant changes in TcP co 2 or oxygen saturation using pulse oximetry (Sp o 2 ). Eight patients (40%) showed a high index of PB, mostly occurring in light sleep and associated with more severe nocturnal hypoxemia. Autotriggering was sporadic and usually limited to one or two breaths, although prolonged and asymptomatic autotriggering occurred in one patient during 10.6% of total sleep time. Conclusions Patient/ventilatory asynchrony and PB are respiratory patterns occurring frequently in OHS patients treated using NPPV. Nocturnal monitoring of Sp o 2 and TcP co 2 , commonly used to assess the efficacy of ventilatory support, do not adequately explore this aspect of therapy that might influence its efficacy as well as sleep quality.

Central sleep apnea (CSA) is characterized by a lack of drive to breathe during sleep, resulting in repetitive periods of insufficient ventilation and compromised gas exchange. These nighttime breathing disturbances can lead to important comorbidity and increased risk of adverse cardiovascular outcomes. There are several manifestations of CSA, including high altitude-induced periodic breathing, idiopathic CSA, narcotic-induced central apnea, obesity hypoventilation syndrome, and Cheyne-Stokes breathing. While unstable ventilatory control during sleep is the hallmark of CSA, the pathophysiology and the prevalence of the various forms of CSA vary greatly. This brief review summarizes the underlying physiology and modulating components influencing ventilatory control in CSA, describes the etiology of each of the various forms of CSA, and examines the key factors that may exacerbate apnea severity. The clinical implications of improved CSA pathophysiology knowledge and the potential for novel therapeutic treatment approaches are also discussed.

Obesity hypoventilation syndrome is becoming an increasingly encountered condition both in respiratory outpatient clinics and in hospitalized patients. The health consequences and social disadvantages of obesity hypoventilation syndrome are significant. Unfortunately, the diagnosis and institution of appropriate therapy is commonly delayed when the syndrome is not recognized or misdiagnosed. Positive airway pressure therapy remains the mainstay of treatment and is effective in controlling sleep-disordered breathing and improving awake blood gases in the majority of individuals. Evidence supporting one mode of therapy over another is limited. Both continuous and bilevel therapy modes can successfully improve daytime gas exchange, with adherence to therapy an important modifiable factor in the response to treatment. Despite adherence to therapy, these individuals continue to experience excess mortality primarily due to cardiovascular events compared with those with eucapnic sleep apnea using CPAP. This difference likely arises from ongoing systemic inflammation secondary to the morbidly obese state. The need for a comprehensive approach to managing nutrition, weight, and physical activity in addition to reversal of sleep-disordered breathing is now widely recognized. Future studies need to evaluate the impact of a more aggressive and comprehensive treatment plan beyond managing sleep-disordered breathing. The impact of early identification and treatment of sleep-disordered breathing on the development and reversal of cardiometabolic dysfunction also requires further attention.

Sleep-disordered breathing (SDB) has a high prevalence in sarcoidosis. This high prevalence may be the result of increased upper airways resistance from sarcoidosis of the upper respiratory tract, corticosteroid-induced obesity, or parenchymal lung involvement from sarcoidosis. OSA is a form of SDB that is particularly common in patients with sarcoidosis. Sarcoidosis and SDB share many similar symptoms and clinical findings, including fatigue, gas exchange abnormalities, and pulmonary hypertension (PH). Sarcoidosis-associated fatigue is a common entity for which stimulants may be beneficial. Sarcoidosis-associated fatigue is a diagnosis of exclusion that requires an evaluation for the possibility of OSA. Hypercapnia is unusual in a patient with sarcoidosis without severe pulmonary dysfunction and, in this situation, should prompt evaluation for alternative causes of hypercapnia, such as SDB. PH is usually mild when associated with OSA, whereas the severity of sarcoidosis-associated PH is related to the severity of sarcoidosis. PH caused by OSA usually responds to CPAP, whereas sarcoidosis-associated PH commonly requires the use of vasodilators. Management of OSA in sarcoidosis is problematic because corticosteroid treatment of sarcoidosis may worsen OSA. Aggressive efforts should be made to place the patient on the lowest effective dose of corticosteroids, which involves early consideration of corticosteroid-sparing agents. Because of the significant morbidity associated with SDB, early recognition and treatment of SDB in patients with sarcoidosis may improve their overall quality of life.

Daytime hypercapnia in patients with obstructive sleep apnea syndrome (OSAS) has a highly variable prevalence in the published studies, and is usually thought to be the consequence of an associated disease, COPD, or severe obesity.To assess the prevalence of daytime hypercapnia in a very large population of adult patients with OSAS, free of associated COPD, and with a wide range of body mass index (BMI), and to evaluate the relationship between daytime hypercapnia and the severity of obesity and obesity-related impairment in lung function.Retrospective analysis of prospectively collected data.The database of the observatory of a national nonprofit network for home treatment of patients with chronic respiratory insufficiency (Association Nationale pour le Traitement a Domicile de l'Insuffisance Respiratoire Chronique) was used. Collected data at treatment initiation were age, apnea-hypopnea index, BMI, FEV(1), vital capacity (VC), and arterial blood gases. The study included 1,141 adult patients with OSAS treated in France with nocturnal nasal continuous positive airway pressure (CPAP), FEV(1)/= 80% predicted, FEV(1)/VC/= 70%, and absence of restrictive respiratory disease other than related to obesity.The prevalence of daytime hypercapnia (Paco(2)/= 45 mm Hg) before initiating CPAP therapy was 11% in the whole study population. The prevalence of daytime hypercapnia was 7.2% (27 of 377 patients) with BMI30, 9.8% (58 of 590 patients) with BMI from 30 to 40, and 23.6% (41 of 174 patients) with BMI40. Patients with daytime hypercapnia had significantly higher BMI values and significantly lower VC, FEV(1), and Pao(2) values than the normocapnic patients. Stepwise multiple regression showed that Pao(2), BMI, and either VC or FEV(1) were the best predictors of hypercapnia, but these variables explained only 9% of the variance in Paco(2) levels.Daytime hypercapnia was observed in1 of 10 patients with OSAS needing CPAP therapy and free of COPD, and was related to the severity of obesity and obesity-related impairment in lung function. However, other mechanisms than obesity are probably involved in the pathogenesis of daytime hypercapnia in OSAS.

Study objectives: To describe a 7-year follow-up (1992 to 2000) of patients who were treated by home nasal positive-pressure ventilation (NPPV) for chronic hypercapnic respiratory failure. Design: Prospective descriptive study. Setting: Two university hospitals and a pulmonary rehabilitation center. Patients: Two hundred eleven patients with obstructive pulmonary disorders (58 patients) or restrictive pulmonary disorders (post-tuberculosis, 23 patients; neuromuscular diseases [NM], 28 patients; post-poliomyelitis syndrome, 12 patients; kyphoscoliosis [KYPH], 19 patients; obesityhypoventilation syndrome [OHS], 71 patients) who were treated by long-term NPPV. Intervention: Annual, elective, standardized medical evaluations. Measurements: Pulmonary function tests, arterial blood gas levels, health status, compliance, survival and probability of pursuing NPPV, and hospitalization rates. Results: Patients with OHS, NM, and KYPH had the highest probability of pursuing NPPV, while patients with COPD had the lowest values. Overall, the compliance rate was high (noncompliance rate, 15%). As of 1994, COPD and OHS became the most frequent indications for NPPV, increasing regularly, while other indications remained stable. The use of pressure-cycled ventilators progressively replaced that of volume-cycled ventilators in most indications. Hospitalization rates decreased in all groups after initiating NPPV, when compared with the year before NPPV, for up to 2 years in COPD patients, and 5 years in non-COPD patients. Conclusion: Major changes in patient selection for NPPV occurred during the study period with a marked increase in COPD and OHS. The shift toward less expensive pressure-cycled ventilators and the decrease in hospitalizations after initiating NPPV have had positive impacts on the cost-effectiveness of NPPV in patients with chronic respiratory failure. (CHEST 2003; 123:67–79)

BACKGROUND Obesity hypoventilation syndrome (OHS) conventionally includes awake hypercapnia, but an isolated raised bicarbonate, even in the absence of awake hypercapnia, may represent evidence of “early” OHS. We investigated whether such individuals exhibit certain features characteristic of established OHS. METHODS Obese subjects (BMI > 30 kg/m 2 ) were identified from a variety of sources and divided into those with (1) normal blood gas measurements and normal acid-base balance, (2) an isolated raised base excess (BE) (≥ 2 mmol/L), and (3) awake hypercapnia (> 6 kPa; ie, established OHS). Two-point ventilatory responses to hypoxia and hypercapnia were performed. Polygraphic sleep studies were done to identify intermittent and prolonged hypoxia. RESULTS Seventy-one subjects (BMI, 47.2; SD, 9.8; age, 52.1 years; SD, 8.8 years) were recruited into three groups (33, 22, and 16 respectively). The Paco 2 and BE values were 5.15, 5.42, 6.62 kPa, and +0.12, +3.01, +4.78 mmol/L, respectively. For nearly all the ventilatory response and sleep study measures, group 2 (with only an isolated raised BE) represented an intermediate group, and for some of the measures they were more similar to the third group with established OHS. CONCLUSIONS These data suggest that obese individuals with a raised BE, despite normocapnia while awake, should probably be regarded as having early obesity-related hypoventilation. This has important implications for clinical management as well as randomized controlled treatment trials, as they may represent a group with a more reversible disease process. TRIAL REGISTRY ClinicalTrials.gov ; No.: NCT01380418; URL: http://www.clinicaltrials.gov

To identify the spectrum of respiratory disturbances during sleep in patients with obesity hypoventilation syndrome (OHS) and to examine the response of hypercapnia to treatment of the specific ventilatory sleep disturbances.Twenty-three patients with chronic awake hypercapnia (mean [+/- SD] PaCO(2), 55 +/- 6 mm Hg) and a respiratory sleep disorder were retrospectively identified. Nocturnal polysomnography testing was performed, and flow limitation (FL) was identified from the inspiratory flow-time contour. Obstructive hypoventilation was inferred from sustained FL coupled with O(2) desaturation that was corrected with treatment of the upper airway obstruction. Central hypoventilation was inferred from sustained O(2) desaturation that persisted after the correction of the upper airway obstruction. Treatment was initiated, and follow-up awake PaCO(2) measurements were obtained (follow-up range, 4 days to 7 years).A variable number of obstructive sleep apneas/hypopneas (ie, obstructive sleep apnea-hypopnea syndrome [OSAHS]) were noted (range, 9 to 167 events per hour of sleep). Of 23 patients, 11 demonstrated upper airway obstruction alone (apnea-hypopnea/FL) and 12 demonstrated central sleep hypoventilation syndrome (SHVS) in addition to a variable number of OSAHS. Treatment aimed at correcting the specific ventilatory abnormalities resulted in correction of the chronic hypercapnia in all compliant patients (compliant patients: pretreatment, 57 +/- 6 mm Hg vs post-treatment, 41 +/- 4 mm Hg [p0.001]; noncompliant patients: pretreatment, 52 +/- 6 mm Hg vs post-treatment, 51 +/- 3 mm Hg; [difference not significant]).This study demonstrates that OHS encompasses a variety of distinct pathophysiologic disturbances that cannot be distinguished clinically at presentation. Sustained obstructive hypoventilation due to partial upper airway obstruction was demonstrated as an additional mechanism for OHS that is not easily classified as SHVS or OSAHS.

Study objectives Obesity has many detrimental effects on the respiratory function and may lead to chronic hypoventilation in some patients, an association known as the obesity-hypoventilation syndrome (OHS). In many cases, patients with OHS also have sleep apneas. Hereafter, we describe several features of a cohort (n = 34) of patients with OHS and show the comparisons with a large cohort (n = 220) of patients with obstructive sleep apnea syndrome (OSAS). We compare also OHS patients with a group of patients with the association of OSAS and COPD, also known as "overlap" patients. Design Descriptive analysis of prospectively collected clinical data. Setting Respiratory care unit and sleep laboratory of university hospital. Results In OHS patients, OSAS was present in most of the cases (23 of 26 patients). However, in three patients, OHS was not associated with OSAS, showing that obesity per se may lead to chronic hypoventilation. As expected by definition, OHS patients had, on average the worst diurnal arterial blood gas measurements, compared to the other groups. For the OHS patients, the mean diurnal Pao 2 was 59 ± 7 mm Hg, which was significantly different from the Pao 2 of the OSAS patients (75 ± 10 mm Hg; p=0,001) but also from the overlap patients (66 ± 10 mm Hg; p=0.015). Pulmonary hypertension ( ie , mean pulmonary artery pressure > 20 mm Hg) was more frequent in OHS patients than in "pure" OSAS patients (58% vs 9%; p=0.001). Conclusion Patients with OSAS and chronic respiratory insufficiency had in most cases an associated OHS or COPD. Patients with OHS were older than patients with pure OSAS. They had mild-to-moderate degrees of restrictive ventilatory pattern due to obesity. Severe gas exchange impairment and pulmonary hypertension were quite frequent. The association of OHS and OSAS was the rule. However, in three patients, OHS was not associated with OSAS, suggesting that OHS is an autonomous disease.

To document health-care utilization (ie, physician claims and hospitalizations) in patients with obesity-hypoventilation syndrome (OHS), for 5 years prior to the diagnosis and for 2 years after the diagnosis and initiation of treatment.Retrospective observational cohort study.University-based sleep disorders center in Manitoba, Canada.Twenty OHS patients (mean [+/- SD] age, 52.7 +/- 9.5 years; body mass index [BMI], 47.3 +/- 11.0 kg/m(2); PaCO(2), 59.7 +/- 13.8 mm Hg; PaO(2), 51.6 +/- 12.4 mm Hg) were matched to two sets of control subjects. First, each case was matched to 15 general population control subjects (GPCs) by age, gender, and geographic location, and, second, each case was matched to a single obese control subject (OBC) who was matched using the same criteria as for the GPCs, plus the measurement of BMI.In the 5 years before diagnosis, the 20 OHS patients had (mean +/- SE) 11.2 +/- 1.8 physician visits per patient per year vs 5.7 +/- 0.8 (p0.01) visits for OBCs and 4.5 +/- 0.4 (p0.001) visits for GPCs. OHS patients generated higher fees, $623 +/- 96 per patient per year for the 5 years prior to diagnosis compared to $252 +/- 34 (p0.001) for OBCs and $236 +/- 25 (p0.001) for GPCs. OHS patients were much more likely to be hospitalized than were subjects in either control group in the 5 years prior to diagnosis (odds ratio [OR] vs GPCs, 8.6) (95% confidence interval [CI], 5.9 to 12.7); OR vs OBCs, 4.9 (95% CI, 2.3 to 10.1). In the 2 years after diagnosis and the initiation of treatment (usually continuous positive airway pressure or bilevel positive airway pressure), there was a significant linear reduction in physician fees. In the 2 years after the initiation of treatment, there was a 68.4% decrease in days hospitalized per year (5 years before treatment, 7.9 days per patient per year; after 2 years of treatment, 2.5 days per patient per year [p = 0.01]).OHS patients are heavy users of health care for several years prior to evaluation and treatment of their sleep breathing disorder; there is a substantial reduction in days hospitalized once the diagnosis is made and treatment is instituted.

To assess the effectiveness of nasal noninvasive mechanical ventilation (NIMV) in patients with obesity hypoventilation syndrome (OHS).Clinical assay that compares two groups of patients with hypercapnic respiratory failure, one group with OHS and the other group with kyphoscoliosis, in their basal situation and after 4 months of treatment with nocturnal NIMV. Thirty-six patients (22 patients with OHS and 14 patients with kyphoscoliosis) completed the study protocol.The frequency of symptoms, such as morning headache, morning drowsiness, dyspnea, and leg edema, improved in a statistically significant way in both groups of patients. The sleepiness improved only in the group with OHS. The comparison of frequency of symptoms between both groups of patients after NIMV treatment did not present statistically significant differences. In the resting situation and without nasal ventilation in place, the PO(2) (mean +/- SD) changed from 51 +/- 10 to 64 +/- 11 mm Hg (p0.001) and PCO(2) from 58 +/- 10 to 45 +/- 5 mm Hg (p0.001) when the patients with OHS were treated with NIMV. In the group of patients with kyphoscoliosis, likewise without nasal ventilation in place, PO(2) changed from 53 +/- 6 to 65 +/- 5 mm Hg (p0.001) and PCO(2) from 59 +/- 11 to 45 +/- 4 mm Hg (p0.001) with NIMV treatment. When we compared PO(2) and PCO(2) in both groups of patients at the beginning and at the end of NIMV treatment, we did not find statistically significant differences between OHS and kyphoscoliosis.NIMV improves the clinical symptoms and the respiratory failure of patients with OHS to a similar degree to that reported for diseases in which its use is completely established, such as kyphoscoliosis. Therefore, NIMV could be an alternative to the treatment of patients with OHS.