Outcome of COPD patients with mild daytime hypoxaemia with or without sleep-related oxygen desaturation

Supplemental oxygen and noninvasive ventilation

The respiratory system attempts to maintain normal levels of oxygen and carbon dioxide. However, airflow limitation, parenchymal abnormalities and dysfunction of the respiratory pump may be compromised in individuals with advanced COPD, eventually leading to respiratory failure, with reduced arterial oxygen tension (hypoxaemia) and/or increased arterial carbon dioxide tension (P aCO2 ; hypercapnia). Hypoxaemia may persist in individuals with severe COPD despite smoking cessation and optimisation of pharmacotherapy. Long-term oxygen therapy (LTOT) can improve survival in those with severe daytime hypoxaemia, whereas those with less severe hypoxaemia may only have improved exercise capacity and dyspnoea. Changes in respiratory physiology that occur during sleep further predispose to hypoxaemia, particularly in individuals with COPD. However, the major cause of hypoxaemia is hypoventilation. Noninvasive ventilation (NIV) may reduce mortality and need for intubation in individuals with COPD and acute hypercapnic respiratory failure. However, NIV may also improve survival and quality of life in individuals with stable, chronic hypercapnia and is now suggested for those with prolonged hypercapnia (e.g. P aCO2 >55 mmHg 2-6 weeks after hospital discharge) when clinically stable and after optimisation of medical therapy including LTOT if indicated. Many questions remain about the optimal mode, settings and goal of NIV therapy.

Pulmonary hypertension in chronic obstructive pulmonary disease and emphysema patients: prevalence, therapeutic options and pulmonary circulatory effects of lung volume reduction surgery

The exact prevalence of pulmonary hypertension (PH) and cor pulmonale (CP) in chronic obstructive pulmonary disease (COPD) is unknown, and varies considerably from 20-91%. Usually, mean pulmonary artery pressure (mPAP) does not exceed 30 mmHg, and PH is not severe. However, PH and CP are important predictors of mortality in COPD and contribute to disability in this disease. Many factors contribute to the development of PH in chronic lung disease, including reduction of the pulmonary vascular cross-sectional area due to parenchymal loss and accompanying hypoxia, effects of abnormal pulmonary mechanics due to hyperinflation, but also vascular remodeling processes. So far, PH associated with chronic lung disease cannot be treated medically. Therefore, it is indicated to treat the underlying pulmonary disease. Patients with severe PH should be referred to centers experienced in the management of PH and enrollment in clinical trials should be considered. Lung volume reduction surgery (LVRS) theoretically further increases pulmonary vascular resistance (PVR) by reducing the vascular bed when resecting lung tissue, however, this might be compensated by better pulmonary mechanics through reduction of hyperinflation, which will be discussed in the present article.

Stressing the Cardiopulmonary Vascular System: The Role of Echocardiography

The cardiopulmonary vascular system represents a key determinant of prognosis in several cardiorespiratory diseases. Although right heart catheterization is considered the gold standard for assessing pulmonary hemodynamics, a comprehensive noninvasive evaluation including left and right ventricular reserve and function and cardiopulmonary interactions remains highly attractive. Stress echocardiography is crucial in the evaluation of many cardiac conditions, typically coronary artery disease but also heart failure and valvular heart disease. In stress echocardiographic applications beyond coronary artery disease, the assessment of the cardiopulmonary vascular system is a cornerstone. The possibility of coupling the left and right ventricles with the pulmonary circuit during stress can provide significant insight into cardiopulmonary physiology in healthy and diseased subjects, can support the diagnosis of the etiology of pulmonary hypertension and other conditions, and can offer valuable prognostic information. In this state-of-the-art document, the topic of stress echocardiography applied to the cardiopulmonary vascular system is thoroughly addressed, from pathophysiology to different stress modalities and echocardiographic parameters, from clinical applications to limitations and future directions.

Supplemental oxygen in patients with stable chronic obstructive pulmonary disease: evidence from Nocturnal Oxygen Treatment Trial to Long-term Oxygen Treatment Trial

PURPOSE OF REVIEW

Oxygen therapy was the first treatment shown to prolong life in patients with chronic obstructive pulmonary disease (COPD) and has been joined by lung volume reduction surgery in selected patients with emphysema, smoking cessation, and potentially noninvasive ventilation in chronic hypercapneic respiratory failure. Although there is consensus around the survival-enhancing effect of supplemental oxygen (SupplO2) for patients with chronic severe hypoxemia at rest, the impact of SupplO2 for COPD patients with moderate hypoxemia and exertional desaturation had been less clear.

RECENT FINDINGS

The recently published Long-term Oxygen Treatment Trial (LOTT) showed no benefit of SupplO2 for the composite outcome of survival and all-cause hospitalizations, or for component outcomes, severe COPD exacerbations, or quality of life in COPD patients with moderate resting hypoxemia or room air normoxemia with exercise desaturation.

SUMMARY

Results of the LOTT challenge the practice of prescribing SupplO2 for patients with COPD and moderate resting hypoxemia or isolated exertional desaturation. In the context that LOTT may not have recruited patients for whom SupplO2 conferred subjective benefit, there may be a role for short-term trials of SupplO2 with assessment of subjective benefit in such patients.

Sleep quality and quality of life in patients with moderate to very severe chronic obstructive pulmonary disease

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is highly associated with obstructive sleep apnea (OSA). Poor sleep quality is found to be related with decreased quality of life (QoL) in patients with COPD but no study assessed this relationship on the basis of nocturnal sleep parameters.

OBJECTIVES

The aim of this study is to explore the relationships between sleep quality, daytime sleepiness and QoL in patients suffering from moderate to very severe COPD with and without sleep apnea assessed objectively and to compare sleep quality, QoL and daytime sleepiness in patients suffering from COPD with and without sleep apnea.

METHODS

Fifty-one patients with stable moderate to very severe COPD (mean age, 59.8 ± 8.1 years) included in the study. The parameters of polygraphic sleep studies (Stardust II, Philips-Respironics) were noted. Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), The Modified Medical Research Council Dyspnea and SF-36 Health Quality Survey were performed.

RESULTS

The rate of OSA was 74.5% (Apnea-Hypopnea Index, >5). out of all the patients, 94% had poor sleep quality (PSQI, >5). Negative correlations were found between PSQI and physical role, social function and mental health of SF-36 subgroups (P < .05). There was no correlation between PSQI, ESS, SF-36, dyspnea and polygraphic parameters (P > .05). In the comparison of patients with or without OSA, the vitality of SF-36 subgroup was found lower in patients with OSA (P < .05).

CONCLUSIONS

In conclusion, irrespective of OSA, patients with COPD are suffering from poor sleep quality and poor sleep quality negatively affects the QoL. Also, COPD and OSA association causes worsened vitality in the terms of health-related QoL.

Long-Term Oxygen Therapy in COPD Patients Who Do Not Meet the Actual Recommendations

Chronic respiratory failure due to chronic obstructive pulmonary disease (COPD) is an increasing problem worldwide. Many patients with severe COPD develop hypoxemic respiratory failure during the natural progression of disease. Long-term oxygen therapy (LTOT) is a well-established supportive treatment for COPD and has been shown to improve survival in patients who develop chronic hypoxemic respiratory failure. The degree of hypoxemia is severe when partial pressure of oxygen in arterial blood (PaO₂) is ≤55 mmHg and moderate if PaO₂ is between 56 and 69 mmHg. Although current guidelines consider LTOT only in patients with severe resting hypoxemia, many COPD patients with moderate to severe disease experience moderate hypoxemia at rest or during special circumstances, such as while sleeping or exercising. The efficacy of LTOT in these patients who do not meet the actual recommendations is still a matter of debate, and extensive research is still ongoing to understand the possible benefits of LTOT for survival and/or functional outcomes such as the sensation of dyspnea, exacerbation frequency, hospitalizations, exercise capacity, and quality of life. Despite its frequent use, the administration of "palliative" oxygen does not seem to improve dyspnea except for delivery with high-flow humidified oxygen. This narrative review will focus on current evidence for the effects of LTOT in the presence of moderate hypoxemia at rest, during sleep, or during exercise in COPD.

Heliox-Driven Nebulization Has a Positive Effect on the Lung Function in Lipopolysaccharide-Induced Chronic Obstructive Pulmonary Disease Rat Model

Background

Chronic obstructive pulmonary disease (COPD) is a serious lung disease that severely threatens people’s health. This study aimed to investigate the effects of heliox-driven nebulization (HDN) on lung function and arterial blood gases in a COPD rat model.

Material/Methods

Twelve healthy male Wistar rats were selected as controls and 34 rats were used to establish a COPD model induced by lipopolysaccharide. Then 6 rats each from the control and model groups were selected for their symptoms to be observed. The remaining 6 normal rats were used as control group (group A) and the remaining 28 experimental COPD rats were randomly assigned to 4 groups: experimental COPD group (group B), medical oxygen group (group C), and heliox groups (group D, He/O₂=63%/37%; group E, He/O₂=71%/29%). The lung function indicators and arterial blood gases were analyzed to evaluate the effects of different driving gases on COPD rats.

Results

The COPD model was successfully established with slow growth and severe lung dysfunction. Inspiratory resistance, expiratory resistance, and forced expiratory volume at 0.10 s (FEV0.10)/FVC were significantly decreased, whereas dynamic lung compliance was significantly increased in groups D and E, compared with the experimental COPD group (group B; P<0.05). Meanwhile, compared with the model group, the values of partial pressure of carbon dioxide in arterial blood were significantly higher, whereas the potential of hydrogen values were significantly lower after atomization in groups C and D but not in group E (P<0.05). The obvious increase in arterial oxygen saturation was found only in group E (P<0.05).

Conclusions

HDN improved the lung function and arterial blood gas analysis results in experimental COPD rats, with an optimal percentage of He/O₂=71%/29%.

Heart rate and blood pressure responses during hypoxic cycles of a 3-week intermittent hypoxia breathing program in patients at risk for or with mild COPD

The aim of this study was to provide information on heart rate and blood pressure responses during a 3-week intermittent hypoxia breathing program in COPD patients. Sixteen participants with COPD symptoms were randomly assigned to a hypoxia or control group and completed a 3-week intermittent hypoxia breathing program (five sessions per week, each consisting of three to five breathing cycles, each cycle lasting 3–5 minutes with 3-minute breaks between cycles). During the breathing cycles, the hypoxia group received hypoxic air (inspired fraction of oxygen 15%–12%), whereas the control group received normal air (sham hypoxia). During the breaks, all participants breathed normoxic room air. Arterial oxygen saturation, systolic and diastolic blood pressure, and heart rate were measured during the normoxic and hypoxic/sham hypoxic periods. For each breathing cycle, changes from normoxia to hypoxia/sham hypoxia were calculated, and changes were averaged for each of the 15 sessions and for each week. Changes in arterial oxygen saturation were significantly different between groups in the course of the 3 weeks (two-way analysis of variance for repeated measures), with post hoc differences in weeks 1, 2, and 3. During the course of the intermittent hypoxia application, no between-group differences were detected for blood pressure or rate pressure product values. Changes in heart rate were significantly different between groups in the course of the 3 weeks (two-way analysis of variance for repeated measures), with post hoc differences only in week 3. Averages over all 15 sessions were significantly higher in the hypoxia group for heart rate and rate pressure product, and tended to be increased for systolic blood pressure. The applied intermittent hypoxia breathing program resulted in specific and moderate heart rate and blood pressure responses, and did not provoke a progressive increase in blood pressure during the hypoxic cycles in the course of the application.

Does the 6-minute walk test predict nocturnal oxygen desaturation in patients with moderate to severe COPD?

Patients with chronic obstructive pulmonary disease (COPD) who have nocturnal oxygen desaturation (NOD) can be treated with nocturnal oxygen therapy (NOT) to avoid possible morbidity and mortality. Although there is no definite data recommending NOT alone, our aim is to evaluate the relationship between desaturation during the six-minute walk test (6MWT) and NOD in COPD. Fifty-five stable patients with COPD were enrolled in this study. The 6MWT and nocturnal oximetry were performed. Patients with comorbid diseases and respiratory failure were excluded. In total, 55 patients (49 males and 6 females, mean age: 65.8 ± 8.4 years) were analysed. Twenty-seven of the patients had moderate COPD and the remainder (n = 28) had severe COPD. Three patients (11%) with moderate COPD and 12 patients (42.9%) with severe COPD desaturated during 6MWT (p = 0.003). NOD was observed in five patients with severe COPD (17.9%). There were no patients with NOD in the moderate COPD group. Three (25%) of patients with severe COPD who desaturated during the 6MWT also had NOD. NOD was more common in patients with severe COPD and the patients with higher carbon dioxide levels (p = 0.02 and p = 0.001). Three patients (11%) with moderate COPD desaturated during the 6MWT; however they did not have NOD. Although the sample size in this study was too small to be conclusive, NOD was more common in desaturators during the 6MWT particularly in patients with severe COPD.

Oxygen therapy for COPD

Chronic obstructive pulmonary disease (COPD) is a leading cause of disability and death globally, characterised by progressive breathlessness, loss of function and, in its later stages, chronic hypoxaemia. Long-term continuous oxygen therapy increases life expectancy in patients with severe resting hypoxaemia. However, there are few data to support the use of oxygen in patients with only mild hypoxaemia and more research is required to determine any benefits of oxygen supplementation in COPD in such individuals.

Sleep-induced hypoxaemia in patients with chronic obstructive pulmonary disease

Patients with moderate or severe chronic obstructive pulmonary disease run a high risk of developing sleep-induced hypoxaemia, because of alveolar hypoventilation and ventilation-perfusion mismatch. This article looks at the prevalence, significance and treatment of sleep-induced hypoxaemia in chronic obstructive pulmonary disease.

Gas exchange in disease: asthma, chronic obstructive pulmonary disease, cystic fibrosis, and interstitial lung disease

Ventilation-perfusion (VA/Q) inequality is the underlying abnormality determining hypoxemia and hypercapnia in lung diseases. Hypoxemia in asthma is characterized by the presence of low VA/Q units, which persist despite improvement in airway function after an attack. This hypoxemia is generally attenuated by compensatory redistribution of blood flow mediated by hypoxic vasoconstriction and changes in cardiac output, however, mediator release and bronchodilator therapy may cause deterioration. Patients with chronic obstructive pulmonary disease have more complex patterns of VA/Q inequality, which appear more fixed, and changes in blood flow and ventilation have less benefit in improving gas exchange efficiency. The inability of ventilation to match increasing cardiac output limits exercise capacity as the disease progresses. Deteriorating hypoxemia during exacerbations reflects the falling mixed venous oxygen tension from increased respiratory muscle activity, which is not compensated by any redistribution of VA/Q ratios. Shunt is not a feature of any of these diseases. Patients with cystic fibrosis (CF) have no substantial shunt when managed according to modern treatment regimens. Interstitial lung diseases demonstrate impaired oxygen diffusion across the alveolar-capillary barrier, particularly during exercise, although VA/Q inequality still accounts for most of the gas exchange abnormality. Hypoxemia may limit exercise capacity in these diseases and in CF. Persistent hypercapnic respiratory failure is a feature of advancing chronic obstructive pulmonary disease and CF, closely associated with sleep disordered breathing, which is not a prominent feature of the other diseases. Better understanding of the mechanisms of hypercapnic respiratory failure, and of the detailed mechanisms controlling the distribution of ventilation and blood flow in the lung, are high priorities for future research.

Long-term oxygen therapy

Long-term oxygen therapy (LTOT) has been shown to reduce pulmonary hypertension and improve survival in patients with chronic obstructive pulmonary disease and resting hypoxemia (reduced arterial partial pressure of oxygen ≤55 mmHg). However, the benefit of its use for chronic pulmonary diseases other than chronic obstructive pulmonary disease as well as for nonpulmonary conditions is debatable. Its role in patients with mild hypoxemia (reduced arterial partial pressure of oxygen >55 mmHg at rest) is presently being investigated in the LOTT. A meta-analysis of four controlled trials reporting the role of LTOT in patients with either nocturnal desaturation or daytime moderate hypoxemia found no difference in survival between patients on LTOT than those without. Advances in oxygen delivery and conservation devices have made domiciliary oxygen therapy more practical and popular for patients. There still remain concerns with the actual compliance of therapy among the needy patients.

Comorbidities and mortality in hypercapnic obese under domiciliary noninvasive ventilation

Background

The higher mortality rate in untreated patients with obesity-associated hypoventilation is a strong rationale for long-term noninvasive ventilation (NIV). The impacts of comorbidities, medications and NIV compliance on survival of these patients remain largely unexplored.

Methods

Observational cohort of hypercapnic obese patients initiated on NIV between March 2003 and July 2008. Survival curves were estimated by the Kaplan–Meier method. Anthropometric measurements, pulmonary function, blood gases, nocturnal SpO₂ indices, comorbidities, medications, conditions of NIV initiation and NIV compliance were used as covariates. Univariate and multivariate Cox models allowed to assess predictive factors of mortality.

Results

One hundred and seven patients (56% women), in whom NIV was initiated in acute (36%) or chronic conditions, were followed during 43±14 months. The 1, 2, 3 years survival rates were 99%, 94%, and 89%, respectively. In univariate analysis, death was associated with older age (>61 years), low FEV1 (<66% predicted value), male gender, BMI×time, concomitant COPD, NIV initiation in acute condition, use of inhaled corticosteroids, ß-blockers, nonthiazide diuretics, angiotensin-converting enzyme inhibitors and combination of cardiovascular drugs (one diuretic and at least one other cardiovascular agent). In multivariate analysis, combination of cardiovascular agents was the only factor independently associated with higher risk of death (HR = 5.3; 95% CI 1.18; 23.9). Female gender was associated with lower risk of death.

Conclusion

Cardiovascular comorbidities represent the main factor predicting mortality in patient with obesity-associated hypoventilation treated by NIV. In this population, NIV should be associated with a combination of treatment modalities to reduce cardiovascular risk.

Chronic obstructive pulmonary disease phenotype desaturator with hypoxic vascular remodelling and pulmonary hypertension obtained by cluster analysis

Significant heterogeneity of clinical presentation and disease progression exists within chronic obstructive pulmonary disease (COPD). This article discusses and refines the concept of desaturator phenotypes in COPD with pulmonary hypertension (PH) obtained by cluster analysis and presents a pattern of phenotypic markers that could be used as a framework for future diagnosis and research. Nocturnal oxygen desaturation results in sleep disturbances which predispose to nocturnal cardiac dysrhythmias, PH and possibly nocturnal death, particularly during acute exacerbations. We assume that in patients with COPD at least two factors play a role in PH: the severity of pulmonary impairment, and the severity of systemic nocturnal hypoxaemia due to reduced pulmonary functions. Establishing a common language for future research will facilitate our understanding and management of such a disease. This knowledge could lead to different pharmacological treatments and other interventions directed at specific phenotypic groups.

Predictors of nocturnal oxyhemoglobin desaturation in COPD

It would be useful to detect predictors of marked nocturnal oxyhemoglobin desaturation (NOD) among COPD patients, who do not have respiratory failure when awake and sleep apnea (SA). Stable COPD patients with awake Pa(O2) ≥ 60 mmHg and Pa(CO2) ≤ 45 mmHg underwent cardio-respiratory polysomnography to exclude SA and to assess NOD. The patients that spent more than 30% of night time with Sp(O2) < 90%, were defined desaturators (D), and the others non desaturators (ND). Pulmonary function testing was performed to determine lung volumes, maximal flow rates, lung diffusion capacity for carbon monoxide and maximal inspiratory and expiratory pressure (P(Imax) and P(Emax)). Negative expiratory pressure test was performed to assess tidal expiratory flow limitation. Supine pharyngometry was performed to determine upper airway size, shuttle walking test to assess exercise desaturation. Twenty-one patients were included in the study (18 male, age 66.0±7.2 years, Body Mass Index 25.9±4.4 kg/m(2), FEV(1) 47.2±16.4% pred., Pa(O2) 74.7±6.9 mmHg, Pa(CO2) 40.3±3.4 mmHg): 10 were D and 11 ND. Significant differences between the two groups were found in diurnal Pa(CO2) (D: 42.4±3.0 vs. ND: 38.3±2.6mmHg; p<0.01), diurnal Sp(O2) (D: 94.0±1.5 vs. ND: 95.9±0.9%; p<0.01), inspiratory capacity (IC) (D: 69.6±11.9 vs. ND: 87.0±17.7% pred.; p<0.05), and oro-pharyngeal junction area (OPJ) (D: 0.8±0.2 vs. ND: 1.2±0.3 cm(2); p<0.01). Among parameters related to marked NOD at the univariate analysis, [Formula: see text] and OPJ remained as independent predictors after stepwise multiple regression analysis. These findings indicate that previously unrecognized factors such as smaller upper airway caliber and lung dynamic hyperinflation are associated with marked NOD in stable COPD patients without daytime respiratory failure and SA.

Chronic obstructive pulmonary disease and cardiovascular mortality in elderly subjects from general population

AIMS

To ascertain whether chronic obstructive pulmonary disease (COPD) is an independent risk factor for cardiovascular (CV) mortality in the elderly subjects from general population.

METHODS

3282 subjects of the Northern Italy aged > or =65 years were followed up for 12 years in the frame of the CArdiovascular STtudy in the ELderly. Multivariate stepwise proportional hazard Cox regression was therefore used to identify the prognostic role of COPD on CV mortality in hypertensive (HT) and normotensive (NT) subjects. The hazard ratio (HR) of COPD with 95% confidence interval (CI) for mortality was adjusted for confounders in both genders.

RESULTS

COPD resulted to be an independent predictor of CV mortality (HR 1.34, CI 1.13-1.61) in HT but not in NT subjects. This was evident both in men (HR 1.44, 1.25-1.95) and women (HR 1.32, CI 1.14-1.53); pulse pressure (PP) was directly related and anti-hypertensive therapy inversely related to risk of CV mortality, an association that was greater in subjects with than without COPD.

CONCLUSION

COPD should be included in the computation of global risk in HT subjects. PP is the main BP component in increasing CV risk in subjects with COPD. Controlled trials should be performed to evaluate the pressor targets to be reached in HT subjects with COPD, with the aim of decreasing their CV risk.

The overlap syndrome: chronic obstructive pulmonary disease and obstructive sleep apnea

The overlap syndrome defines the relationship between obstructive sleep apnea (OSA) and chronic obstructive pulmonary disease (COPD), and is a commonly noted but poorly studied disorder. Individuals who have the overlap syndrome have been recognized to have greater risk for pulmonary hypertension, right heart failure, and hypercapnia than patients who have either disorder alone. In patients who have advanced-stage COPD, concomitant OSA likely has significant adverse consequences. The interaction between these two diseases is unclear, however. Further clinical trials of the overlap syndrome are urgently needed.

The prevalence of nocturnal hypoxemia in advanced cancer

Nocturnal hypoxemia is associated with excessive daytime sleepiness in patients with chronic respiratory disease. This relationship has not been explored in patients with cancer. This study examined the prevalence of nocturnal hypoxemia in patients admitted to a specialist palliative care unit, and explored relationships with demographic and physiological parameters, opioid or other sedative drug use, and daytime sleepiness, fatigue, and quality of life. Demographic details, diagnosis, performance status, body mass index, opioid or other sedative drug use, hemoglobin, spirometry, and sniff nasal inspiratory pressures were obtained, along with Epworth Sleepiness Scale, Multidimensional Fatigue Inventory, and Short Form-36 health questionnaire scores. An oximeter recorded resting daytime oxygen saturation (SaO2); overnight SaO2 was recorded for a minimum of five hours. Nocturnal hypoxemia was defined as SaO2<90% for >or=2% of the monitored nighttime. Of 100 patients, 35 had nocturnal hypoxemia. These were more likely to have lung disease (P<0.05), a lower forced expiratory volume in one second % predicted (P=0.01), lower daytime SaO2 (P=0.01) and higher levels of mental fatigue (difficulty concentrating) (P=0.02), compared to those without nocturnal hypoxemia. Both groups exhibited abnormal levels of daytime sleepiness. Nocturnal hypoxemia is common in this group of patients and may contribute to mental fatigue (difficulty concentrating).

Respiratory disorders during sleep in chronic obstructive pulmonary disease

Patients with COPD may show slow, progressive deteriorations in arterial blood gases during the night, particularly during rapid eye movement (REM) sleep. This is mainly due to hypoventilation, while a deterioration of ventilation/perfusion mismatch plays a minor role. The severity of gas exchanges alterations is proportional to the degree of impairment of diurnal pulmonary function tests, particularly of partial pressure of oxygen (PaO₂) and of carbon dioxide (PaCO₂) in arterial blood, but correlations between diurnal and nocturnal blood gas levels are rather loose. Subjects with diurnal PaO₂ of 60–70 mmHg are distinguished in “desaturators” and “nondesaturators” according to nocturnal oxyhemoglobin saturation behavior. The role of nocturnal hypoxemia as a determinant of alterations in sleep structure observed in COPD is dubious. Effects of the “desaturator” condition on pulmonary hemodynamics, evolution of diurnal blood gases, and life expectancy are also controversial. Conversely, it is generally accepted that occurrence of sleep apneas in COPD is associated with a worse evolution of the disease. Nocturnal polysomnographic monitoring in COPD is usually performed when coexistence of sleep apnea (“overlap syndrome”) is suspected, while in most other cases nocturnal oximetry may be enough. Nocturnal oxygen attenuates sleep desaturations among stable patients, without increases in PaCO₂ of clinical concern. Nocturnal treatment with positive pressure ventilators may give benefit to some stable hypercapnic subjects and patients with the overlap syndrome.

Circadian-rhythm differences among emergency department patients with chronic obstructive pulmonary disease exacerbation

The purpose of the study was determine whether patients with chronic obstructive pulmonary disease (COPD) exacerbation who present to the emergency department (ED) during the night (00:00 to 07:59 h) vs. other times of the day have more severe COPD exacerbation, require more intensive treatment, and have worse clinical outcomes. A multicenter cohort study was completed involving 29 EDs in the United States and Canada. Using a standard protocol, consecutive ED patients with COPD exacerbation were interviewed, and their charts were reviewed. Of 582 patients enrolled, 52% were women, and the median age was 71 yrs (interquartile range, 64-77 yrs). Nighttime patients (15% of cohort) did not differ from patients presenting at other times except that they were less likely to have private insurance, more likely to have a history of corticosteroid use, and have a shorter duration of symptoms exacerbation. Except for a few features indicative of more severe COPD exacerbation (such as higher respiratory rate at ED presentation, greater likelihood of receiving noninvasive positive pressure ventilation, and increased risk of endotracheal intubation), nighttime patients did not differ from other patients with respect to ED management. Nighttime patients were approximately three-fold more likely to be intubated in the ED (odds ratio, 3.46; 95% confidence interval, 1.10-10.9). There were no day-night differences regarding ED disposition and post-ED relapse. Except for some features indicating more severe exacerbation, nighttime ED patients had similar chronic COPD characteristics, received similar treatments in the ED, and had similar clinical outcomes compared with patients presenting to the ED at other times of the day.

Chronic obstructive pulmonary disease as a risk factor for stroke-related seizures

Chronic obstructive pulmonary disease (COPD) is a risk factor for cardiovascular disorders and different types of stroke. The present retrospective study investigates whether COPD is also a risk factor for the development of seizures in stroke patients. The study population consisted of 237 patients with stroke-related seizures. The control population was composed of 939 patients, admitted for a stroke between 2002 and 2004 and who did not develop epileptic spells on a follow up of 2 years. The stroke type and aetiology, and the vascular risk factors, including COPD, were compared. The seizure patients were older (P = 0.009) and had more arterial hypertension (P = 0.046) and cardiac-embolic strokes (P = 0.045) than the control group. On logistic regression only partial anterior circulation syndrome/infarct (PACS/I) and COPD (P < 0.001) emerged as independent risk factors for the development of seizures in stroke patients. The occurrence of seizures was not related to the severity of the COPD or to its type of treatment. The present study confirms that seizures occur most frequently in patients with a PACS/I. Although we were unable to demonstrate why COPD is a risk factor for seizures in stroke patients, its frequent associated nocturnal oxygen desaturation seems to be the most plausible explanation. Further prospective are needed to assess the role of COPD as a possible independent risk factor for stroke-related seizures.

Pulmonary hypertension associated with chronic respiratory disease

Pulmonary hypertension (PH) has long been recognized as a complication of chronic respiratory disease. Recent studies have highlighted the adverse impact PH has on the clinical course of these conditions and have cast doubt on the role of hypoxia in their pathogenesis. Clinicians should carefully consider the possibility of PH during the diagnostic evaluation of chronic respiratory disorders. The usefulness of pharmacologic therapy directed toward PH remains to be determined.

Dessaturação noturna: preditores e influência no padrão do sono de pacientes portadores de doença pulmonar obstrutiva crônica com hipoxemia leve em vigília

OBJETIVO: Verificar o padrão da oximetria noturna em portadores de doença pulmonar obstrutiva crônica sem apnéia do sono e com hipoxemia leve em vigília, identificar prováveis parâmetros diurnos capazes de predizer a dessaturação noturna e verificar sua influência no padrão de sono. MÉTODOS: Avaliaram-se 25 pacientes, divididos em dois grupos: com e sem dessaturação noturna. RESULTADOS: Comparando-se o primeiro grupo (52%) com o segundo observou-se: idade, 63 ± 5 versus 63 ± 6 anos; volume expiratório forçado no primeiro segundo, 53 ± 31% versus 56 ± 19% do previsto; relação entre volume expiratório forçado no primeiro segundo e capacidade vital forçada, 49 ± 14% versus 52 ± 10%; pressão parcial de oxigênio no sangue arterial, 68 ± 8mmHg versus 72 ± 68mmHg; saturação arterial de oxigênio, 93 ± 2% versus 94 ± 1%. O grupo com dessaturação noturna apresentou menores valores de saturação arterial de oxigênio diurna e saturação periférica de oxigênio noturna. Não houve diferença no padrão de sono entre os grupos. Houve correlação da relação entre o volume expiratório forçado no primeiro segundo e a capacidade vital forçada, pressão parcial de oxigênio no sangue arterial e saturação arterial de oxigênio diurnas, e saturação periférica de oxigênio no exercício com os níveis de saturação periférica de oxigênio noturna, porém somente a saturação arterial de oxigênio diurna foi preditora da dessaturação noturna. CONCLUSÃO: A única variável capaz de predizer dessaturação noturna foi a saturação arterial de oxigênio diurna. A dessaturação noturna não influencia o padrão de sono de portadores de doença pulmonar obstrutiva crônica com hipoxemia diurna leve.

Pattern of variables describing desaturator COPD patients, as revealed by cluster analysis

STUDY OBJECTIVES

The aims of this study were to define, by cluster analysis, a pattern of clinical variables that differentiate desaturator (D) from nondesaturator (ND) patients affected by COPD, and to identify daytime variables that are predictive of nocturnal desaturation.

PATIENTS

Fifty-one random, consecutive COPD outpatients (20 women; mean [+/- SD] age, 69.6 +/- 4.0 years) with mild daytime hypoxemia (Pao(2), 60 to 70 mm Hg) were enrolled into the study. Obstructive sleep apnea syndrome patients were excluded.

MEASUREMENTS AND RESULTS

Lung volumes, arterial blood gas levels, and mean pulmonary artery pressure (MPAP) were measured, and nocturnal desaturation was evaluated with nighttime polygraphy. With least squares simple linear regression, the percentage of total recording time was highly correlated with a total nocturnal recording time of arterial oxygen saturation of < 90 mm Hg (T90) and MPAP (R = 0.84; R2= 71.20%); T90 was also highly correlated with daytime Paco2 (R = 0.70; R2= 48.96%). Multiple regression showed that T90 was highly correlated with both MPAP and Paco2 (R2= 97.75%). Hierarchical cluster analysis conducted with these three variables showed that D and ND patients differed in both nocturnal and daytime variables. The mean T90 was 30 +/- 3.5% in 19.2% and 8%, respectively, of the D and ND groups. Moreover, two D subgroups differing in MPAP and two ND subgroups differing in Paco2 were identified.

CONCLUSIONS

D patients may be identified by a pattern of T90, MPAP, and Paco2 values, rather than by T90 alone, with the latter two variables being predictors of nocturnal desaturation severity.

[Relevance of sleep for patients with lung diseases]

Sleep is characterized by a profound change of load and capacity of the respiratory system. Load increases due to a rise in upper and lower airway resistance. Capacity decreases due to reduced chemosensitivity, a decrease in muscle activity and minute ventilation. Whereas these changes do not lead to relevant blood gas changes and do not disturb sleep in healthy subjects, patients with respiratory diseases frequently show the first symptoms of their disease during sleep. Pulmonary diseases in which sleep plays an important role are asthma, COPD, hypercapnic respiratory failure, sleep disordered breathing, the overlap-syndrome and cystic fibrosis. Medical history should include sleep and complaints during the night. In asthmatics peak-flow measurements during the night may provide valuable information. In all other disorders mentioned, nocturnal ambulatory recording of respiration and arterial oxygen saturation often allow the detection of relevant disorders of breathing during sleep. If ambulatory monitoring reveals relevant pathology, then further evaluation and treatment in the sleep laboratory are warranted.

Influência da reabilitação pulmonar sobre o padrão de sono de pacientes portadores de doença pulmonar obstrutiva crônica

INTRODUÇÃO: A Reabilitação Pulmonar (RP) melhora a qualidade de vida de pacientes portadores de doença pulmonar obstrutiva crônica (DPOC). No entanto, o papel da RP sobre o padrão de sono destes pacientes ainda não está estabelecido. OBJETIVO: Avaliar a influência da RP sobre o padrão de sono de pacientes portadores de DPOC. MÉTODO: Foram estudados 27 pacientes (22 homens), que foram submetidos a exames espirométricos, gasométricos, antropométricos e polissonográficos antes e depois de seis semanas de RP, além de responderem a escala de sonolência de Epworth. A análise estatística foi realizada pelo teste t de Student para amostras pareadas, ANOVA e o teste de comparações múltiplas Newmans-Keuls. RESULTADOS: Observamos que os pacientes estudados tinham idade média de 63 ± 5 anos, VEF1 = 55 ± 25% do previsto, VEF1/CVF = 50 ± 12%, PaO2 em repouso de 70 ± 7mmHg e SaO2 igual a 94 ± 2%. A polissonografia revelou sono fragmentado, redução do sono delta e dessaturação da hemoglobina, cujas maiores quedas ocorreram durante o sono REM. Não houve diferença estatisticamente significativa (p>0,05) na comparação entre as variáveis estudadas antes e após RP. CONCLUSÃO: No grupo de pacientes estudados, o programa de RP não modificou o padrão de sono.

Arterial oxygen saturation, COPD, and cerebral small vessel disease

OBJECTIVE

To study whether lower arterial oxygen saturation (SaO(2)) and chronic obstructive pulmonary disease (COPD) are associated with cerebral white matter lesions and lacunar infarcts.

METHODS

We measured SaO(2) twice with a pulse oximeter, assessed the presence of COPD, and performed MRI in 1077 non-demented people from a general population (aged 60-90 years). We rated periventricular white matter lesions (on a scale of 0-9) and approximated a total subcortical white matter lesion volume (range 0-29.5 ml). All analyses were adjusted for age and sex and additionally for hypertension, diabetes, body mass index, pack years smoked, cholesterol, haemoglobin, myocardial infarction, and left ventricular hypertrophy.

RESULTS

Lower SaO(2) was independent of potential confounders associated with more severe periventricular white matter lesions (score increased by 0.12 per 1% decrease in SaO(2) (95% confidence interval 0.01 to 0.23)). Participants with COPD had more severe periventricular white matter lesions than those without (adjusted mean difference in score 0.70 (95% confidence interval 0.23 to 1.16)). Lower SaO(2) and COPD were not associated with subcortical white matter lesions or lacunar infarcts.

CONCLUSION

Lower SaO(2) and COPD are associated with more severe periventricular white matter lesions.

Sleep and chronic obstructive pulmonary disease

PURPOSE OF REVIEW

Sleep disorders are pervasive in patients with chronic obstructive pulmonary disease (COPD). The patient with COPD is especially vulnerable to sleep-induced gas exchange aberrations. Most sleep disturbances affect the quality of life and some potentially affect survival in these patients. These issues impact treatment of these patients.

RECENT FINDINGS

Insomnia is very common in COPD but might respond to inhaled anticholinergic agents. The use of hypnotics in the hypercapnic patient with severe COPD might be dangerous. The incidence of sleep apnea in COPD patients is allegedly very high, but recent studies suggest this association to be artifactual. Nocturnal oxygen desaturation, which is common in these patients, occurs even in mild COPD. This clinical complication might reflect sleep-disordered breathing or REM sleep-related hypoventilation. We need cost-effective and reliable methods to help distinguish between these causes without routinely resorting to formal polysomnography.

SUMMARY

Development of sound clinical algorithms to address this clinical dilemma is indeed a focus for future research. Some of these patients might require continuous positive pressure therapy, whereas others might need long-term oxygen therapy. Although oxygen therapy in COPD patients with only mild hypoxemia and nocturnal desaturation has not uniformly been shown to be beneficial, it is perhaps too soon to abandon this important clinical intervention in these patients.