Sergi Marti

Mortality in severe sleep apnoea/hypopnoea syndrome patients: impact of treatment

The aim of this study was to determine mortality in patients with sleep apnoea/hypopnoea syndrome (SAHS) according to the treatments employed and comorbidity. An historical cohort of patients with SAHS diagnosed at a university hospital between 1982 and 1992 and followed until 1996 was studied. From a total of 475 SAHS patients, 444 (94%), with a mean±sd apnoea/hypopnoea index at diagnosis of 55±27, were located and included in the study. SAHS treatments employed were: surgery (88), weight loss (134), continuous positive airway pressure (124) and 98 patients were not treated. By the end of follow-up, 49 patients had died. According to Cox regression analysis, mortality in treated patients was lower than in those not treated, but higher in those with a history of severe chronic obstructive pulmonary disease. Mortality in nontreated patients compared with that of the general population, adjusted for age and sex, showed excessive mortality, which decreased in treated patients. Stratification by age showed a greater mortality rate ratio in patients <50 yrs. These findings were maintained when mortality from cardiovascular causes was compared. In conclusion, a rise in mortality was found in nontreated sleep apnoea/hypopnoea syndrome patients compared with the general population, whereas mortality in those treated for sleep apnoea/hypopnoea syndrome did not differ significantly from that of the general population.

Body weight and comorbidity predict mortality in COPD patients treated with oxygen therapy

The aim of this study was to investigate the association between clinical variables and all-cause and respiratory mortality in patients with chronic obstructive pulmonary disease (COPD) undergoing long-term oxygen therapy (LTOT). The authors retrospectively studied a historic cohort of 128 patients with COPD (126 males, mean age±sd 68.9±9.7 yrs, body mass index (BMI) 25.1±4.5 kg·m−2, and forced expiratory volume in one second 25.4±8.8% predicted), who were being treated with long-term oxygen therapy in a tertiary teaching hospital between 1992 and 1999. Comorbidity, assessed with the Charlson Index, was present in 38% of the patients. Vital status and cause of death were assessed through the population death registry. A total of 78 patients (61%) had died by the end of follow-up. Three-year survival was 55%. Death was due to respiratory causes in 77% of cases. On Cox analysis, BMI <25 kg·m−2, comorbid conditions, age ≥70 yrs and cor pulmonale were associated with all-cause mortality. The BMI and comorbidity were the only significant predictive factors when the analysis was restricted to respiratory mortality. In conclusion, body mass index <25 kg·m−2 and comorbidity were predictors of all-cause and respiratory mortality in a cohort of chronic obstructive pulmonary disease patients treated with long-term oxygen therapy. These factors should be taken into account when considering the management and prognosis of these patients.

Long-term efficacy of dietary weight loss in sleep apnoea/hypopnoea syndrome

Weight loss is associated with clinical improvement in sleep apnoea/ hypopnoea syndrome (SAHS). The aim of this study was to ascertain whether the therapeutic efficacy of dietary weight loss is maintained in the long-term. From a total of 216 overweight SAHS patients treated by only a weight reduction programme, 24 cured by this method (apnoea/hypopnoea index (AHI) at diagnosis 443+/-27.8, after weight loss 3+/-3.1) were re-evaluated after a mean (+/-SD) period of 94.3+/-27.4 months post-cure. No correlation was found between changes in AHI and body mass index experienced by each patient in the two phases of the study (diagnosis to cure and cure to long-term follow-up), r=0.29, p=0.156, demonstrating a marked intra-individual variability. Six of the 13 patients who maintained their weight presented recurrence of SAHS (AHI 40.5+/-24.1) as did eight of the 11 who had regained weight (AHI 44.3+/-23.). Weight maintenance was more frequent among patients who had continued to attend periodic appointments, 10/11 versus 3/13 (p<0.001). In conclusion, weight-loss efficacy is maintained in the long-term in some sleep apnoea/hypopnoea syndrome patients. This study indicates the need for periodic follow-up of these patients as a reinforcement for weight maintenance and for early detection of the reappearance of sleep apnoea/hypopnoea syndrome.

Efficacy of Different Treatment Alternatives for Obesity Hypoventilation Syndrome. Pickwick Study

RATIONALE The incidence of obesity hypoventilation syndrome (OHS) may be increasing in parallel with the present obesity epidemic. Despite extensive noninvasive ventilation (NIV) and continuous positive airway pressure (CPAP) use in patients with OHS, information regarding efficacy is limited. OBJECTIVES We performed a large, multicenter randomized controlled study to determine the comparative efficacy of NIV, CPAP, and lifestyle modification (control group) using daytime PaCO2 as the main outcome measure. METHODS Sequentially screened patients with OHS with severe sleep apnea were randomized into the above-mentioned groups for a 2-month follow up. Arterial blood gas parameters, clinical symptoms, health-related quality-of-life assessments, polysomnography, spirometry, 6-minute-walk distance, dropouts, compliance, and side effects were evaluated. Statistical analysis was performed using intention-to-treat analysis, although adjustments for CPAP and NIV compliance were also analyzed. MEASUREMENTS AND MAIN RESULTS In total, 351 patients were selected, and 221 were randomized. NIV yielded the greatest improvement in PaCO2 and bicarbonate, with significant differences relative to the control group but not relative to the CPAP group. In the CPAP group, PaCO2 improvement was significantly different than in the control group only after CPAP compliance adjustment. Additionally, clinical symptoms and polysomnographic parameters improved similarly with NIV and CPAP relative to the control. However, some health-related quality-of-life assessments, the spirometry, and 6-minute-walk distance results improved more with NIV than with CPAP. Dropouts were similar between groups, and compliance and secondary effects were similar between NIV and CPAP. CONCLUSIONS NIV and CPAP were more effective than lifestyle modification in improving clinical symptoms and polysomnographic parameters, although NIV yielded better respiratory functional improvements than did CPAP. Long-term studies must demonstrate whether this functional improvement has relevant implications. Clinical trial registered with www.clinicaltrials.gov (NCT01405976).

Performance of mechanical ventilators at the patient’s home: a multicentre quality control study

Background: Quality control procedures vary considerably among the providers of equipment for home mechanical ventilation (HMV). Methods: A multicentre quality control survey of HMV was performed at the home of 300 patients included in the HMV programmes of four hospitals in Barcelona. It consisted of three steps: (1) the prescribed ventilation settings, the actual settings in the ventilator control panel, and the actual performance of the ventilator measured at home were compared; (2) the different ventilator alarms were tested; and (3) the effect of differences between the prescribed settings and the actual performance of the ventilator on non-programmed readmissions of the patient was determined. Results: Considerable differences were found between actual, set, and prescribed values of ventilator variables; these differences were similar in volume and pressure preset ventilators. The percentage of patients with a discrepancy between the prescribed and actual measured main ventilator variable (minute ventilation or inspiratory pressure) of more than 20% and 30% was 13% and 4%, respectively. The number of ventilators with built in alarms for power off, disconnection, or obstruction was 225, 280 and 157, respectively. These alarms did not work in two (0.9%), 52 (18.6%) and eight (5.1%) ventilators, respectively. The number of non-programmed hospital readmissions in the year before the study did not correlate with the index of ventilator error. Conclusions: This study illustrates the current limitations of the quality control of HMV and suggests that improvements should be made to ensure adequate ventilator settings and correct ventilator performance and ventilator alarm operation.

Impact of Occupational Exposure on Severity of COPD

BACKGROUND The relationship between occupational exposures and COPD has been analyzed in population-based and occupational cohort studies. However, the influence of these exposures on the clinical characteristics of COPD is not well known. The aim of this study was to analyze the impact of occupational exposures on respiratory symptoms, lung function, and employment status in a series of COPD patients. METHODS We conducted a cross-sectional study of 185 male COPD patients. Patients underwent baseline spirometry and answered a questionnaire that included information on respiratory symptoms, hospitalizations for COPD, smoking habits, current employment status, and lifetime occupational history. Exposure to biological dust, mineral dust, and gases and fumes was assessed using an ad hoc job exposure matrix. RESULTS Having worked in a job with high exposure to mineral dust or to any dusts, gas, or fumes was associated with an FEV(1) of < 30% predicted (mineral dust: relative risk ratio, 11; 95% confidence interval [CI], 1.4 to 95; dusts, gas, or fumes: relative risk ratio, 6.9; 95% CI, 1.1 to 45). High exposure to biological dust was associated with chronic sputum production (odds ratio [OR], 4.3; 95% CI, 1.6 to 12), dyspnea (OR, 2.7; 95% CI, 1.1 to 6.7), and work inactivity (OR, 2.4; 95% CI, 1.4 to 4.2). High exposure to dusts, gas, or fumes was associated with sputum production (OR, 2.8; 95% CI, 1.2 to 6.7) and dyspnea (OR, 1.2; 95% CI, 1.1 to 1.4). CONCLUSIONS Occupational exposures are independently associated with the severity of airflow limitation, respiratory symptoms, and work inactivity in patients with COPD.

Non-invasive ventilation in obesity hypoventilation syndrome without severe obstructive sleep apnoea

Background Non-invasive ventilation (NIV) is an effective form of treatment in patients with obesity hypoventilation syndrome (OHS) who have concomitant severe obstructive sleep apnoea (OSA). However, there is a paucity of evidence on the efficacy of NIV in patients with OHS without severe OSA. We performed a multicentre randomised clinical trial to determine the comparative efficacy of NIV versus lifestyle modification (control group) using daytime arterial carbon dioxide tension (PaCO2) as the main outcome measure. Methods Between May 2009 and December 2014 we sequentially screened patients with OHS without severe OSA. Participants were randomised to NIV versus lifestyle modification and were followed for 2 months. Arterial blood gas parameters, clinical symptoms, health-related quality of life assessments, polysomnography, spirometry, 6-min walk distance test, blood pressure measurements and healthcare resource utilisation were evaluated. Statistical analysis was performed using intention-to-treat analysis. Results A total of 365 patients were screened of whom 58 were excluded. Severe OSA was present in 221 and the remaining 86 patients without severe OSA were randomised. NIV led to a significantly larger improvement in PaCO2 of −6 (95% CI −7.7 to −4.2) mm Hg versus −2.8 (95% CI −4.3 to −1.3) mm Hg, (p<0.001) and serum bicarbonate of −3.4 (95% CI −4.5 to −2.3) versus −1 (95% CI −1.7 to −0.2 95% CI)  mmol/L (p<0.001). PaCO2 change adjusted for NIV compliance did not further improve the inter-group statistical significance. Sleepiness, some health-related quality of life assessments and polysomnographic parameters improved significantly more with NIV than with lifestyle modification. Additionally, there was a tendency towards lower healthcare resource utilisation in the NIV group. Conclusions NIV is more effective than lifestyle modification in improving daytime PaCO2, sleepiness and polysomnographic parameters. Long-term prospective studies are necessary to determine whether NIV reduces healthcare resource utilisation, cardiovascular events and mortality. Trial registration number NCT01405976; results.

Sleep hypoventilation due to increased nocturnal oxygen flow in hypercapnic COPD patients.

Background and objective:  Several COPD treatment guidelines recommend increasing oxygen flow during sleep to avoid nocturnal desaturation. However, such an increase could have deleterious clinical and gas exchange effects. The objective of this study was to evaluate short‐term gas exchange alterations produced by increasing the nocturnal oxygen flow rate.

Protective Cardiovascular Effect of Sleep Apnea Severity in Obesity Hypoventilation Syndrome

BACKGROUND Obesity hypoventilation syndrome (OHS) is associated with a high burden of cardiovascular morbidity (CVM) and mortality. The majority of patients with OHS have concomitant OSA, but there is a paucity of data on the association between CVM and OSA severity in patients with OHS. The objective of our study was to assess the association between CVM and OSA severity in a large cohort of patients with OHS. METHODS In a cross-sectional analysis, we examined the association between OSA severity based on tertiles of oxygen desaturation index (ODI) and CVM in 302 patients with OHS. Logistic regression models were constructed to quantify the independent association between OSA severity and prevalent CVM after adjusting for various important confounders. RESULTS The prevalence of CVM decreased significantly with increasing severity of OSA based on ODI as a continuous variable or ODI tertiles. This inverse relationship between OSA severity and prevalence of CVM was seen in the highest ODI tertile and it persisted despite adjustment for multiple confounders. Chronic heart failure had the strongest negative association with the highest ODI tertile. No significant CVM risk change was observed between the first and second ODI tertiles. Patients in the highest ODI tertile were younger, predominantly male, more obese, more hypersomnolent, had worse nocturnal and daytime gas exchange, lower prevalence of hypertension, better exercise tolerance, and fewer days hospitalized than patients in the lowest ODI tertile. CONCLUSIONS In patients with OHS, the highest OSA severity phenotype was associated with reduced risk of CVM. This finding should guide the design of future clinical trials assessing the impact of interventions aimed at decreasing cardiovascular morbidity and mortality in patients with OHS. TRIAL REGISTRY Clinicaltrial.gov; No.: NCT01405976; URL: www.clinicaltrials.gov.

Predicting nocturnal hypoventilation in hypercapnic chronic obstructive pulmonary disease patients undergoing long-term oxygen therapy.

Background: Chronic obstructive pulmonary disease (COPD) patients are very sensitive to changes in pulmonary mechanics and central ventilation control during sleep and may develop significant gas exchange alterations with increased hypoxemia and hypercapnia. Oxygen therapy improves nocturnal desaturation but can worsen hypoventilation. Objectives: To analyze the prevalence of nocturnal hypoventilation (NHV) in hypercapnic COPD patients and to determine predictive factors for this phenomenon. Methods: This was a prospective multicenter study which enrolled 80 clinically stable COPD patients with hypercapnic respiratory failure who fulfilled the conventional criteria for long-term oxygen therapy (LTOT). All patients had undergone pulmonary function testing, blood gas analysis, and respiratory polygraphy. Arterial blood gas samples were obtained while patients were awake and during sleep. NHV was considered when an increase in PaCO2 >10 mm Hg was observed in any nocturnal arterial blood gas sample as compared to the awake levels. Results: Seventeen patients (21%) developed NHV. NHV was associated with the values of BMI, hemoglobin, hematocrits, DLCO, and PaO2 reached after oxygen administration. In the logistic regression analysis BMI (OR 1.26, 95% CI 1.068–1.481; p = 0.006) and the diurnal increase of PaO2 after O2 (OR 0.89, 95% CI 0.807–0.972; p = 0.010) were the variables that best discriminated with a sensitivity of 82% and a specificity of 78%. Conclusions: NHV is a relatively common finding in stable hypercapnic COPD patients undergoing LTOT and it is related to a higher BMI and lower PaO2 after oxygen administration.