Metabolic cost of unloading pedalling in different groups of patients with pulmonary hypertension and volunteers

Recently, the parameter internal work (IW) has been introduced as change in oxygen uptake (VO2) between resting and unloading workload in cardiopulmonary exercise testing (CPET). The proportional IW (PIW) was defined as IW divided by VO2 at peak exercise. A second option is to calculate the PIW based on the workload [PIW (Watt)] by considering the aerobic efficiency. The aim of our study was to investigate whether IW and PIW differ between patients with and without pulmonary hypertension and healthy controls. Our study population consisted of 580 patients and 354 healthy controls derived from the Study of Health in Pomerania. The PIW was slightly lower in patients (14.2%) than in healthy controls (14.9%; p = 0.030), but the PIW (Watt) was higher in patients (18.0%) than in the healthy controls (15.9%; p = 0.001). Such a difference was also observed, when considering only the submaximal workload up to the VAT (19.8% in patients and 15.1% in healthy controls; p < 0.001). Since the PIW (Watt) values were higher in patients with pulmonary hypertension, this marker may serve as a useful CPET parameter in clinical practice. In contrast to most of the currently used CPET parameters, the PIW does not require a maximal workload for the patient. Further studies are needed to validate the prognostic significance of the PIW.

Sleep characteristics and parameters of bone turnover and strength in the adult population: results from the Study of Health in Pomerania-TREND

Poor sleep quality or sleep deprivation may be related to decreased bone mineral density. We aimed to assess whether associations of sleep characteristics and bone turnover or strength are present in adults from the general population and whether these are independent of common risk factors such as sex, age, and obesity. A total of 1037 participants from the Study of Health in Pomerania-TREND underwent laboratory-based polysomnography and quantitative ultrasound measurements at the heel. Of these participants, 804 completed standardised questionnaires to assess daytime sleepiness, insomnia, and sleep quality. Serum concentrations of two bone turnover markers, intact amino-terminal propeptide of type 1 procollagen (P1NP) and carboxy-terminal telopeptide of type 1 collagen (CTX) were measured. Cross-sectional associations of polysomnography variables (total sleep time, sleep efficiency, time spent wake after sleep onset, oxygen desaturation index, apnea-hypopnea index, and obstructive sleep apnea [OSA]), as well as sleep questionnaire scores with the bone turnover markers and the ultrasound-based stiffness index were assessed in linear regression models. In adjusted models, higher insomnia scores and lower sleep quality scores were related to a higher bone turnover in women but not in men. However, associations between polysomnography variables or questionnaire scores and the stiffness index were absent. Our study provides limited evidence for relationships between sleep characteristics and bone turnover and strength independent of common risk factors for OSA and osteoporosis. Nevertheless, women reporting poor sleep or insomnia in combination with risk factors for osteoporosis might benefit from an evaluation of bone health.

Acute COPD exacerbation treatment with noninvasive ventilation

The establishment of a guideline for long-term noninvasive ventilation treatment (LTH-NIV) of acute hypercapnic exacerbations of chronic obstructive pulmonary disease (AECOPD) requiring acute ventilation has proven elusive. Most studies thus far have shown no mortality benefit of long-term noninvasive ventilation treatment. Using retrospective analysis of the data of our patients (n = 143) recruited from 2012 to 2019, we aimed to compare patients discharged with and without long-term noninvasive ventilation. The follow-up results showed no significant difference (p = 0.233) between the groups [LTH-NIV (n = 83); non-NIV (n = 60)] regarding readmission due to clinical worsening. However, the first- and second-year survival rates were 82% and 72%, respectively, in the LTH-NIV group and significantly different (p = 0.023) from 67 and 55% in the non-NIV group. The statistical models showed a significant mortality risk for the non-NIV group, with a hazard ratio (HR) of 2.82 (1.31; 6.03). To the best of our knowledge, this is the first study to demonstrate the mortality benefit of long-term NIV therapy for patients with AECOPD under real-world conditions.

Menopause Is Associated with Obstructive Sleep Apnea in a Population-Based Sample from Mecklenburg–Western Pomerania, Germany

Objective: Menopause is associated with multiple health risks. In several studies, a higher incidence or a higher risk for obstructive sleep apnea (OSA) in post-menopausal than pre-menopausal women is reported. This study was designed to verify such a connection between menopause and OSA in a population-based sample. Methods: For a subsample (N = 1209) of the Study of Health in Pomerania (N = 4420), complete polysomnography data was available. Of these, 559 females completed a structured interview about their menstrual cycle. Splines and ordinal regression analysis were used to analyze the resulting data. Results: In the ordinal regression analysis, a significant association between the apnea–hypopnea index (AHI) and menopause indicated that post-menopausal women had a substantially higher risk of OSA. In accordance with previous studies, risk indicators such as body mass index (BMI), age, and the influence of hysterectomies or total oophorectomies were included in the model. Conclusions: Our results clearly confirmed the assumed connection between menopause and OSA. This is important because OSA is most often associated with male patients, and it warrants further research into the underlying mechanisms.

Quality of life in patients with obstructive sleep apnea: Results from the study of health in Pomerania

Obstructive sleep apnea is known to be an overall public health problem that, among other things, increases morbidity and mortality. Risk factors as well as symptoms of this multidimensional sleep-related breathing disorder negatively affect quality of life. With our study we aimed to expose the association between obstructive sleep apnea and quality of life in the population of Pomerania, Germany. We utilized data from the population-based Study of Health in Pomerania (SHIP). Information on health status and risk factors about 4420 participants (2275 women) were gathered within the cohort SHIP-TREND, of which 1209 (559 women) underwent an overnight polysomnography and completed sleep questionnaires. The quality of life of the participants was measured using the Short-Form 12 questionnaire. For our study, an ordinal regression analysis with age, sex, body mass index and the Short-Form 12 health survey as predictors for apnea-hypopnea index was computed. The potential factors affecting quality of life are different between physical and mental dimensions of quality of life. Significant effects were found regarding age, sex, body mass index and the Short-Form 12 Mental Component Score, but not the Physical Component Score.

Do brachycephaly and nose size predict the severity of obstructive sleep apnea (OSA)? A sample-based geometric morphometric analysis of craniofacial variation in relation to OSA syndrome and the role of confounding factors

Obstructive sleep apnea is a common disorder that leads to sleep fragmentation and is potentially bidirectionally related to a variety of comorbidities, including an increased risk of heart failure and stroke. It is often considered a consequence of anatomical abnormalities, especially in the head and neck, but its pathophysiology is likely to be multifactorial in origin. With geometric morphometrics, and a large sample of adults from the Study for Health in Pomerania, we explore the association of craniofacial morphology to the apnea-hypopnea index used as an estimate of obstructive sleep apnea severity. We show that craniofacial size and asymmetry, an aspect of morphological variation seldom analysed in obstructive sleep apnea research, are both uncorrelated to apnea-hypopnea index. In contrast, as in previous analyses, we find evidence that brachycephaly and larger nasal proportions might be associated to obstructive sleep apnea severity. However, this correlational signal is weak and completely disappears when age-related shape variation is statistically controlled for. Our findings suggest that previous work might need to be re-evaluated, and urge researchers to take into account the role of confounders to avoid potentially spurious findings in association studies.

Comparison between thermodilution and Fick methods for resting and exercise‐induced cardiac output measurement in patients with chronic dyspnea

Studies comparing thermodilution (TD) and the direct Fick method (dFM) for cardiac output (CO) measurement are rare. We compared CO measurements between TD (2–5 cold water injections), the dFM, and indirect Fick method (iFM) at rest and during exercise, and assessed the effect of averaging different numbers of TD measurements during exercise. This retrospective study included 300 patients (52.3% women, mean age 66 ± 11 years) having pulmonary hypertension (76.0%) or unexplained dyspnea. Invasive hemodynamic and gas exchange parameters were measured at rest (supine; n = 300) and during unloaded cycling (semi‐supine; n = 275) and 25‐W exercise (semi‐supine; n = 240). All three methods showed significant differences in CO measurement (ΔCO) at rest (p ≤ 0.001; ΔCO > 1 L/min: 45.0% [iFM vs. dFM], 42.0% [iFM vs. TD], and 45.7% [TD vs. dFM]). ΔCO (TD vs. dFM) was significant during unloaded cycling (p < 0.001; ΔCO > 1 L/min: 56.6%) but not during 25‐W exercise (p = 0.137; ΔCO > 1 L/min: 52.8%). ΔCO (TD vs. dFM) during 25‐W exercise was significant when using one or two (p ≤ 0.01) but not three (p = 0.06) TD measurements. Mean ΔCO (TD [≥3 measurements] vs. dFM) was −0.43 ± 1.98 and −0.06 ± 2.29 L/min during unloaded and 25‐W exercise, respectively. Thus, TD and dFM CO measurements are comparable during 25‐W exercise (averaging ≥3 TD measurements), but not during unloaded cycling or at rest. Individual ΔCOs vary substantially and require critical interpretation to avoid CO misclassification.

Socioeconomic factors do not predict sleep apnea in a population sample from Mecklenburg-Western Pomerania, Germany

PURPOSE

Socioeconomic factors are known to modulate health. Concerning sleep apnea, influences of income, education, work, and living in a partnership are established. However, results differ between national and ethnic groups. Results also differ between various clinical studies and population-based approaches. The goal of our study was to determine if such factors can be verified in the population of Pomerania, Germany.

METHODS

A subgroup from the participants of the population-based Study of Health in Pomerania volunteered for an overnight polysomnography. Their data were subjected to an ordinal regressions analysis with age, sex, body mass index (BMI), income, education, work, and life partner as predictors for the apnea-hypopnea index.

RESULTS

Among the subgroup (N = 1209) from the population-based study (N = 4420), significant effects were found for age, sex, and BMI. There were no significant effects for any of the socioeconomic factors.

CONCLUSION

Significant effects for well-established factors as age, sex, and BMI show that our study design has sufficient power to verify meaningful associations with sleep apnea. The lack of significant effects for the socioeconomic factors suggests their clinical irrelevance in the tested population.

Correlation of Hemodynamic and Respiratory Parameters in Invasive Cardiopulmonary Exercise Testing (iCPET)

Background: Invasive cardiopulmonary exercise testing (iCPET) is an integral part in the advanced diagnostic workup of pulmonary hypertension (PH). Our study evaluated the relation between hemodynamic and respiratory parameters at two different resting conditions and two defined low exercise levels with a close synchronization of measurements in a broad variety of dyspnea patients. Subjects and methods: We included 146 patients (median age 69 years, range 22 to 85 years, n = 72 female) with dyspnea of uncertain origin. Invasive hemodynamic and gas exchange parameters were measured at rest, 45° upright position, unloaded cycling, 25 and 50 W exercise. All measurements were performed in a single RHC procedure. Results: Oxygen uptake (VO2/body mass) correlated significantly with cardiac index (all p ≤ 0.002) at every resting and exercise level and with every method of cardiac output measurement (thermodilution, method of Fick). Mean pulmonary arterial pressure (PAPmean) correlated with all respiratory parameters (respiratory rate, partial end-tidal pressures of oxygen and carbon dioxide [petCO2 and petO2], ventilation/carbon dioxide resp. oxygen ratio [VE/VCO2, VE/VO2], and minute ventilation [VE], all p < 0.05). These correlations improved with increasing exercise levels from rest via unloaded cycling to 25 W. There was no correlation with right atrial or pulmonary arterial wedge pressure. Summary: In dyspnea patients of different etiologies, the cardiac index is closely linked to VO2 at every level of rest and submaximal exercise. PAPmean is the only pressure that correlates with different respiratory parameters, but this correlation is highly significant and stable at rest, unloaded cycling and at 25 W.

[Risk Stratification in Patients with Pulmonary Arterial Hypertension under Treatment - Results of Four German Centers]

Risk stratification plays an essential role in the management of patients with pulmonary arterial hypertension (PAH). According to the current European guidelines the expected 1-year risk of mortality for PAH patients can be categorized as low, intermediate, or high, based on clinical, non-invasive and hemodynamic data.Data from 131 patients with incident PAH (age 64 ± 14) and frequent comorbidities (in 66.4 %) treated between 2016 and 2018 at 4 German PH centers were analyzed. At baseline, most patients were classified as intermediate risk (76 %), 13.8 % as high risk and only 9.9 % as low risk.During follow-up while on treatment after 12 ± 3 months (range 9-16 months) 64.9 % were still classified as intermediate risk (76 %), 14.4 % as high risk and 20.7 % as low risk.Survival at 12 and 24 months was 96 % and 82 % in the intermediate risk group, while only 89 % and 51 % of the high risk patients were alive at these time points. In contrast, all patients in the low risk category were alive at 24 months.Despite the availability of various treatment options for patients with PAH even in specialized centers only a minority of patients can be stabilized in the low risk group associated with a good outcome.

Value of Cardiopulmonary Exercise Testing in the Prognosis Assessment of Chronic Obstructive Pulmonary Disease Patients: A Retrospective, Multicentre Cohort Study

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is one of the most common chronic diseases associated with high mortality. Previous studies suggested a prognostic role for peak oxygen uptake (VO2peak) assessed during cardiopulmonary exercise testing (CPET) in patients with COPD. However, most of these studies had small sample sizes or short follow-up periods, and despite their relevance, CPET parameters are not included in the Global Initiative for Chronic Obstructive Lung Disease (GOLD) tool for assessment of severity.

OBJECTIVES

We therefore aimed to assess the prognostic value of CPET parameters in a large cohort of outpatients with COPD.

METHODS

In this retrospective, multicentre cohort study, medical records of patients with COPD who underwent CPET during 2004-2017 were reviewed and demographics, smoking habits, GOLD grade and category, exacerbation frequency, dyspnoea score, lung function measurements, and CPET parameters were documented. Relationships with survival were evaluated using Kaplan-Meier analysis, Cox regression, and receiver operating characteristic (ROC) curves.

RESULTS

Of a total of 347 patients, 312 patients were included. Five-year and 10-year survival probability was 75% and 57%, respectively. VO2peak significantly predicted survival (hazard ratio: 0.886 [95% confidence interval: 0.830; 0.946]). The optimal VO2peak threshold for discrimination of 5-year survival was 14.6 mL/kg/min (area under ROC curve: 0.713). Five-year survival in patients with VO2peak <14.6 mL/kg/min versus ≥ 14.6 mL/kg/min was 60% versus 86% in GOLD categories A/B and 64% versus 90% in GOLD categories C/D.

CONCLUSIONS

We confirm that VO2peak is a highly significant predictor of survival in COPD patients and recommend the incorporation of VO2peak into the assessment of COPD severity.

Association Between Obstructive Sleep Apnea and Brain White Matter Hyperintensities in a Population-Based Cohort in Germany

Importance

Underlying pathomechanisms of brain white matter hyperintensities (WMHs), commonly observed in older individuals and significantly associated with Alzheimer disease and brain aging, have not yet been fully elucidated. One potential contributing factor to WMH burden is chronic obstructive sleep apnea (OSA), a disorder highly prevalent in the general population with readily available treatment options.

Objective

To investigate potential associations between OSA and WMH burden.

Design, Setting, and Participants

Analyses were conducted in 529 study participants of the Study of Health in Pomerania-Trend baseline (SHIP-Trend-0) study with complete WMH, OSA, and important clinical data available. SHIP-Trend-0 is a general population-based, cross-sectional, observational study to facilitate the investigation of a large spectrum of common risk factors, subclinical disorders, and clinical diseases and their relationships among each other with patient recruitment from Western Pomerania, Germany, starting on September 1, 2008, with data collected until December 31, 2012. Data analysis was performed from February 1, 2019, to January 31, 2021.

Exposures

The apnea-hypopnea index (AHI) and oxygen desaturation index (ODI) were assessed during a single-night, laboratory-based polysomnography measurement.

Main Outcomes and Measures

The primary outcome was WMH data automatically segmented from 1.5-T magnetic resonance images.

Results

Of 529 study participants (mean [SD] age, 52.15 [13.58] years; 282 female [53%]), a total of 209 (40%) or 102 (19%) individuals were diagnosed with OSA according to AHI or ODI criteria (mean [SD] AHI, 7.98 [12.55] events per hour; mean [SD] ODI, 3.75 [8.43] events per hour). Both AHI (β = 0.024; 95% CI, 0.011-0.037; P <.001) and ODI (β = 0.033; 95% CI, 0.014-0.051; P <. 001) were significantly associated with brain WMH volumes. These associations remained even in the presence of additional vascular, metabolic, and lifestyle WMH risk factors. Region-specific WMH analyses found the strongest associations between periventricular frontal WMH volumes and both AHI (β = 0.0275; 95% CI, 0.013-0.042, P < .001) and ODI (β = 0.0381; 95% CI, 0.016-0.060, P < .001) as well as periventricular dorsal WMH volumes and AHI (β = 0.0165; 95% CI, 0.004-0.029, P = .008).

Conclusions and Relevance

This study found significant associations between OSA and brain WMHs, indicating a novel, potentially treatable WMH pathomechanism.

Associations between sleep apnea and advanced brain aging in a large-scale population study

Advanced brain aging is commonly regarded as a risk factor for neurodegenerative diseases, for example, Alzheimer's dementia, and it was suggested that sleep disorders such as obstructive sleep apnea (OSA) are significantly contributing factors to these neurodegenerative processes. To determine the association between OSA and advanced brain aging, we investigated the specific effect of two indices quantifying OSA, namely the apnea-hypopnea index (AHI) and the oxygen desaturation index (ODI), on brain age, a score quantifying age-related brain patterns in 169 brain regions, using magnetic resonance imaging and overnight polysomnography data from 690 participants (48.8% women, mean age 52.5 ± 13.4 years) of the Study of Health in Pomerania. We additionally investigated the mediating effect of subclinical inflammation parameters on these associations via a causal mediation analysis. AHI and ODI were both positively associated with brain age (AHI std. effect [95% CI]: 0.07 [0.03; 0.12], p-value: 0.002; ODI std. effect [95% CI]: 0.09 [0.04; 0.13], p-value: < 0.0003). The effects remained stable in the presence of various confounders such as diabetes and were partially mediated by the white blood cell count, indicating a subclinical inflammation process. Our results reveal an association between OSA and brain age, indicating subtle but widespread age-related changes in regional brain structures, in one of the largest general population studies to date, warranting further examination of OSA in the prevention of neurodegenerative diseases.

Monotherapy in patients with pulmonary arterial hypertension at four German PH centres

Background

Although combination therapy is the gold standard for patients with pulmonary arterial hypertension (PAH), some of these patients are still being treated with monotherapy.

Methods

We conducted a retrospective analysis at four German PH centres to describe the prevalence and characteristics of patients receiving monotherapy.

Results

We identified 131 incident PAH patients, with a mean age of 64 ± 13.8 years and a varying prevalence of comorbidities, cardiovascular risk factors and targeted therapy. As in other studies, the extent of prescribed PAH therapy varied with age and coexisting diseases, and younger, so-called “typical” PAH patients were more commonly treated early with combination therapy (48% at 4–8 months). In contrast, patients with multiple comorbidities or cardiovascular risk factors were more often treated with monotherapy (69% at 4–8 months). Survival at 12 months was not significantly associated with the number of PAH drugs used (single, dual, triple therapy) and was not different between “atypical” and “typical” PAH patients (89% vs. 85%).

Conclusion

Although “atypical” PAH patients with comorbidities or a more advanced age are less aggressively treated with respect to combination therapy, the outcome of monotherapy in these patients appears to be comparable to that of dual or triple therapy in “typical” PAH patients.

[Evaluation of Weaning Success in Long-Term Invasively Ventilated Patients at a Weaning Center]

Despite the use of enormous personnel and other resources in German weaning centers, approximately 20 % of patients currently fail to get weaned from mechanical ventilation (MV) and need out-of-hospital ventilation.Between 03/2015 and 11/2019, we carried out a pilot project with 33 patients (48 % female, mean age 68 ± 11 years at hospital admission) in order to re-evaluate their options of a possible weaning from MV. At this stage the patients had been invasively ventilated for 475 ± 775 days. The mean stay in our weaning center was 26 ± 19 days. 24/33 (73.53 %) patients were successfully weaned from MV. Of those, 11/24 (44 %) were discharged with non-invasive out-of-hospital ventilation. The completely weaned patients had a survival period of 3 or 12 months (92 % and 77 %), respectively. In those discharged with non-invasive ventilation, the survival period of 3 or months was 91 % and 81 %, respectively. In those discharged with invasive ventilation, this was 86 % and 71 %, respectively.The current results demonstrate that even those undergoing long-term out-of-hospital invasive ventilation can be successfully weaned from MV. Therefore, we suggest regular re-evaluations of weaning opportunities in invasively ventilated ambulatory patients.

A 10-year follow-up of key gas exchange exercise parameters in a general population: results of the Study of Health in Pomerania

Background

Cardiopulmonary exercise testing (CPET) is a frequently used method for the evaluation of the cardiorespiratory system. The prognostic relevance of the measured parameters is commonly known. Longitudinal data on cardiorespiratory fitness in a large sample of well-characterised healthy volunteers are rare in the literature.

Methods

CPET data of 615 healthy individuals who voluntarily took part in the Study of Health in Pomerania (SHIP) at three different measurement times were analysed. The median observation time was 10.5 years. The age range was 25–85 years.

Results

Over the observed timeframe and with increasing age, a decline in maximum power, peak oxygen uptake (V′_O2peak) and oxygen uptake at anaerobic threshold (V′_O2@AT) was detectable. This decline was aggravated with increasing age. For the minute ventilation (V′_E)/carbon dioxide production (V′_CO2) slope, an increase was measured in individuals aged ≥50 years only.

Conclusion

The present study affirms the decrease in aerobic capacity with increasing age in a selected, well-characterised, healthy study sample, which seems to be less pronounced in females.

A 10-year follow-up of the Study of Health in Pomerania affirms the decrease in aerobic capacity with increasing age in a selected, well-characterised, healthy study sample, which seems to be less pronounced in femaleshttps://bit.ly/3pIJmpM

Reference Values for Pulmonary Single-Breath Diffusing Capacity - Results of the "Study of Health in Pomerania"

OBJECTIVES

 The assessment of pulmonary single-breath diffusing capacity is a frequently performed diagnostic procedure and considered as an important tool in medical surveillance examinations of pulmonary diseases.The aim of this study was to establish reference equations for pulmonary single-breath diffusing capacity parameters in a representative adult-population across a wide age range and to compare the normative values from this sample with previous ones.

METHODS

 Diffusing capacity measurement was carried out in 3566 participants (1811 males) of a cross-sectional, population-based survey ("Study of Health in Pomerania - SHIP").

RESULTS

 Individuals with cardiopulmonary disorders and current smoking habits were excluded, resulting in 1786 healthy individuals (923 males), aged 20 - 84 years. Prediction equations for both sexes were established by quantile regression analyses, taking into consideration the influence of age, height, weight and former smoking.

CONCLUSION

 The study provides a novel set of prediction equations for pulmonary single-breath diffusing capacity in an adult Caucasian population. The results are comparable to previously reported equations, underline their importance and draw attention to the need for up-to-date reference equations that adequately take into account both the subjects' origin, age, anthropometric characteristics and the equipment used.

Predictors of survival after prolonged weaning from mechanical ventilation

PURPOSE

Weaning from mechanical ventilation is a key component of intensive care treatment; however, this process may be prolonged as some patients require care at specialised centres. Current data indicate that weaning from invasive mechanical ventilation is successful in approximately 65% of patients; however, data on long-term survival after discharge from a weaning centre are limited.

MATERIALS AND METHODS

We analysed predictors of survival among 597 patients (392 men, mean age 68 ± 11) post-discharge from a specialised German weaning centre.

RESULTS

Complete weaning from mechanical ventilation was achieved in 407 (57.8%) patients, and 106 patients (15.1%) were discharged with non-invasive ventilation; thus, prolonged weaning was successful in 72.9% of the patients. The one-year and five-year survival rates post-discharge were 66.5% and 37.1%, respectively. Age, duration of mechanical ventilation, certain clusters of comorbidities, and discharged with mechanical ventilation significantly influenced survival (p < .001). Completely weaned patients who were discharged with a tracheostomy had a significantly reduced survival rate than did those who were completely weaned and discharged with a closed tracheostomy (p = .004).

CONCLUSIONS

The identified predictors of survival after prolonged weaning could support therapeutic strategies during patients' intensive care unit stay. Patients should be closely monitored after discharge from a weaning centre.

Exercise and fluid challenge during right heart catheterisation for evaluation of dyspnoea

This prospective study compared exercise test and intravenous fluid challenge in a single right heart catheter procedure to detect latent diastolic heart failure in patients with echocardiographic heart failure with preserved ejection function. We included 49 patients (73% female) with heart failure with preserved ejection function and pulmonary artery wedge pressure ≤15 mmHg. A subgroup of 26 patients had precapillary pulmonary hypertension. Invasive haemodynamic and gas exchange parameters were measured at rest, 45° upright position, during exercise, after complete haemodynamic and respiratory recovery in lying position, and after rapid infusion of 500 mL isotonic solution. Most haemodynamic parameters increased at both exercise and intravenous fluid challenge, with the higher increase at exercise. Pulmonary vascular resistance decreased by –0.21 wood units at exercise and –0.56 wood units at intravenous fluid challenge (p = 0.3); 20% (10 of 49) of patients had an increase in pulmonary artery wedge pressure above the upper limit of 20 mmHg at exercise, and 20% above the respective limit of 18 mmHg after intravenous fluid challenge. However, only three patients exceeded the upper limit of pulmonary artery wedge pressure in both tests, i.e. seven patients only at exercise and seven other patients only after intravenous fluid challenge. In the subgroup of pulmonary hypertension patients, only two patients exceeded pulmonary artery wedge pressure limits in both tests, further five patients at exercise and four patients after intravenous fluid challenge. A sequential protocol in the same patient showed a significantly higher increase in haemodynamic parameters at exercise compared to intravenous fluid challenge. Both methods can unmask diastolic dysfunction at right heart catheter procedure, but in different patient groups.

A Biased Diffusion Approach to Sleep Dynamics Reveals Neuronal Characteristics

We propose a biased diffusion model of accumulated subthreshold voltage fluctuations in wake-promoting neurons to account for stochasticity in sleep dynamics and to explain the occurrence of brief arousals during sleep. Utilizing this model, we derive four neurophysiological parameters related to neuronal noise level, excitability threshold, deep-sleep threshold, and sleep inertia. We provide the first analytic expressions for these parameters, and we show that there is good agreement between empirical findings from sleep recordings and our model simulation results. Our work suggests that these four parameters can be of clinical importance because we find them to be significantly altered in elderly subjects and in children with autism.

Interobserver variability of ventilatory anaerobic threshold in asymptomatic volunteers

Background: The ventilatory anaerobic threshold (VO2@AT) has been used in preoperative risk assessment and rehabilitation for many years. Our aim was to determine the interobserver variability of AT using cardiopulmonary exercise (CPET) data from a large epidemiological study (SHIP, Study of Health in Pomerania). Methods: VO2@AT was determined from CPET of 1,079 cross-sectional volunteers, according to American Heart Association guidelines. VO2@AT determinations were compared between two experienced physicians, between physicians and qualified medical assistants, and between physicians or medical assistants and software-based algorithms. For the first 522 data sets, the two physicians discussed discrepant readings to reach consensus; the remaining data sets were analyzed without consensus discussion. Results: VO2@AT was detectable in 1,056 data sets. The physicians recorded identical VO2@AT values in 319 out of 522 cases before consensus discussion (61.1%; intraclass correlation coefficient [ICC]: 0.90; 95% confidence interval [CI]: 0.88–0.92) and in 700 out of 1,056 cases overall (66.3%; ICC: 0.95; 95% CI: 0.95–0.96), with an interobserver difference of 0 ± 8% (95% limits of agreement [LOA]: ±161 mL/min). The interobserver difference was − 2 ± 18% (95% LOA: ±418 mL/min) between a physician and medical assistants, and − 19 ± 24% to − 22 ± 26% (95% LOAs: ±719–806 mL/min) between physicians or medical assistants and software-based algorithms. Conclusions: Experienced physicians show high agreement when determining AT in asymptomatic volunteers. However, agreement between physicians and qualified medical assistants is lower, and there is substantial deviation in AT determination between physicians or medical assistants and software-based algorithms. This must be considered when using AT as a decision tool.

Interobserver variability of ventilatory anaerobic threshold in asymptomatic volunteers

Background

The ventilatory anaerobic threshold (VO₂@AT) has been used in preoperative risk assessment and rehabilitation for many years. Our aim was to determine the interobserver variability of AT using cardiopulmonary exercise (CPET) data from a large epidemiological study (SHIP, Study of Health in Pomerania).

Methods

VO₂@AT was determined from CPET of 1,079 cross-sectional volunteers, according to American Heart Association guidelines. VO₂@AT determinations were compared between two experienced physicians, between physicians and qualified medical assistants, and between physicians or medical assistants and software-based algorithms. For the first 522 data sets, the two physicians discussed discrepant readings to reach consensus; the remaining data sets were analyzed without consensus discussion.

Results

VO₂@AT was detectable in 1,056 data sets. The physicians recorded identical VO₂@AT values in 319 out of 522 cases before consensus discussion (61.1%; intraclass correlation coefficient [ICC]: 0.90; 95% confidence interval [CI]: 0.88-0.92) and in 700 out of 1,056 cases overall (66.3%; ICC: 0.95; 95% CI: 0.95-0.96), with an interobserver difference of 0 ± 8% (95% limits of agreement [LOA]: ±161 mL/min). The interobserver difference was - 2 ± 18% (95% LOA: ±418 mL/min) between a physician and medical assistants, and - 19 ± 24% to - 22 ± 26% (95% LOAs: ±719-806 mL/min) between physicians or medical assistants and software-based algorithms.

Conclusions

Experienced physicians show high agreement when determining AT in asymptomatic volunteers. However, agreement between physicians and qualified medical assistants is lower, and there is substantial deviation in AT determination between physicians or medical assistants and software-based algorithms. This must be considered when using AT as a decision tool.

Prevalence and association analysis of obstructive sleep apnea with gender and age differences - Results of SHIP-Trend

Identification of obstructive sleep apnea and risk factors is important for reduction in symptoms and cardiovascular risk, and for improvement of quality of life. The population-based Study of Health in Pomerania investigated risk factors and clinical diseases in a general population of northeast Germany. Additional polysomnography was applied to measure sleep and respiration with the objective of assessing prevalence and risk factors of obstructive sleep apnea in a German cohort. One-thousand, two-hundred and eight people between 20 and 81 years old (54% men, median age 54 years) underwent overnight polysomnography. The estimated obstructive sleep apnea prevalence was 46% (59% men, 33% women) for an apnea-hypopnea index ≥5%, and 21% (30% men, 13% women) for an apnea-hypopnea index ≥ 15. The estimated obstructive sleep apnea syndrome prevalence (apnea-hypopnea index ≥5; Epworth Sleepiness Scale >10) was 6%. The prevalence of obstructive sleep apnea continuously increased with age for men and women with, however, later onset for women. Gender, age, body mass index, waist-to-hip ratio, snoring, alcohol consumption (for women only) and self-reported cardiovascular diseases were significantly positively associated with obstructive sleep apnea, whereas daytime sleepiness was not. Diabetes, hypertension and metabolic syndrome were positively associated with severe obstructive sleep apnea. The associations became non-significant after adjustment for body mass. Women exhibited stronger associations than men. The prevalence of obstructive sleep apnea was high, with almost half the population presenting some kind of obstructive sleep apnea. The continuous increase of obstructive sleep apnea with age challenges the current theory that mortality due to obstructive sleep apnea and cardiovascular co-morbidities affect obstructive sleep apnea prevalence at an advanced age. Also, gender differences regarding obstructive sleep apnea and associations are significant for recognizing obstructive sleep apnea mechanisms and therapy responsiveness.

Peripheral Artery Disease and Its Clinical Relevance in Patients with Chronic Obstructive Pulmonary Disease in the COPD and Systemic Consequences-Comorbidities Network Study

RATIONALE

Knowledge about the prevalence of objectively assessed peripheral artery disease (PAD) and its clinical relevance in patients with chronic obstructive pulmonary disease (COPD) is scarce.

OBJECTIVES

We aimed to: (1) assess the prevalence of PAD in COPD compared with distinct control groups; and (2) study the association between PAD and functional capacity as well as health status.

METHODS

The ankle-brachial index was used to diagnose PAD (ankle-brachial index ≤ 0.9). The 6-minute-walk distance, health status (St. George's Respiratory Questionnaire), COPD Assessment Test, and EuroQol-5-Dimensions were assessed in patients enrolled in the German COPD and Systemic Consequences-Comorbidities Network cohort study. Control groups were derived from the Study of Health in Pomerania.

MEASUREMENTS AND MAIN RESULTS

A total of 2,088 patients with COPD (61.1% male; mean [SD] age, 65.3 [8.2] years, GOLD (Global Initiative for Chronic Obstructive Lung Disease) stages I-IV: 9.4, 42.5, 37.5, and 10.5%, respectively) were included, of which 184 patients (8.8%; GOLD stage I-IV: 5.1, 7.4, 11.1, and 9.5%, respectively, vs. 5.9% in patients with GOLD stage 0 in the COPD and Systemic Consequences-Comorbidities Network) had PAD. In the Study of Health in Pomerania, PAD ranged from 1.8 to 4.2%. Patients with COPD with PAD had a significantly shorter 6-minute-walk distance (356 [108] vs. 422 [103] m, P < 0.001) and worse health status (St. George's Respiratory Questionnaire: 49.7 [20.1] vs. 42.7 [20.0] points, P < 0.001; COPD Assessment Test: 19.6 [7.4] vs. 17.9 [7.4] points, P = 0.004; EuroQol-5-Dimensions visual analog scale: 51.2 [19.0] vs. 57.2 [19.6], P < 0.001). Differences remained significant after correction for several confounders.

CONCLUSIONS

In a large cohort of patients with COPD, 8.8% were diagnosed with PAD, which is higher than the prevalence in control subjects without COPD. PAD was associated with a clinically relevant reduction in functional capacity and health status.

[Weaning Unit of the University Medicine Greifswald - Institutional Structure and Weaning Results from Prolonged Ventilation over 10 Years]

The increasing importance of intensive care medicine including mechanical ventilation has been accompanied by the demand of weaning opportunities for patients undergoing prolonged mechanical ventilation. Consequently, specialised clinical institutions, focusing on the weaning from mechanical ventilation, have been established since the 1980 s.The present article illustrates the structural development and results of such a specialised institution at the University Medicine Greifswald, using data of 616 patients collected within the past ten years (2006 - 2015). Across the years, a shift in the underlying disease leading to mechanical ventilation can be found, with rising numbers of patients suffering from pneumonia/sepsis and declining numbers of patients who underwent cardiac surgery in advance. The days with mechanical ventilation outside (p = 0.004) and within the investigated institution (p = 0.02) are significantly declining. The percentage of successfully weaned patients increased from 62.7 % (2006 - 2010) to 77.3 % (2011 - 2015), p < 0.001. Consecutively, the percentage of patients who remained mechanically ventilated decreased from 16.4 % to 9.6 % (p < 0.001) and the share of in-hospital deceased patients significantly declined from 20.9 % to 13.0 % (p < 0.001). Furthermore, the one-year-survival after hospital discharge in successful weaned patients was 72 percent. The present data, collected at the University Medicine Greifswald are quite comparable to data of other German institutions that are specialised on weaning from mechanical ventilation.

Sex Hormones and Sleep in Men and Women From the General Population: A Cross-Sectional Observational Study

CONTEXT AND OBJECTIVES

Associations between sex hormones and sleep habits originate mainly from small and selected patient-based samples. We examined data from a population-based sample with various sleep characteristics and the major part of sex hormones measured by mass spectrometry.

DESIGN, SETTING, AND PARTICIPANTS

We used data from 204 men and 213 women of the cross-sectional Study of Health in Pomerania-TREND.

MAIN OUTCOME AND MEASURES

Associations of total T (TT) and free T, androstenedione (ASD), estrone, estradiol (E2), dehydroepiandrosterone-sulphate, SHBG, and E2 to TT ratio with sleep measures (including total sleep time, sleep efficiency, wake after sleep onset, apnea-hypopnea index [AHI], Insomnia Severity Index, Epworth Sleepiness Scale, and Pittsburgh Sleep Quality Index) were assessed by sex-specific multivariable regression models.

RESULTS

In men, age-adjusted associations of TT (odds ratio 0.62; 95% confidence interval (CI) 0.46-0.83), free T, and SHBG with AHI were rendered nonsignificant after multivariable adjustment. In multivariable analyses, ASD was associated with Epworth Sleepiness Scale (β-coefficient per SD increase in ASD: -0.71; 95% CI: -1.18 to -0.25). In women, multivariable analyses showed positive associations of dehydroepiandrosterone-sulphate with wake after sleep onset (β-coefficient: .16; 95% CI 0.03-0.28) and of E2 and E2 to TT ratio with Epworth Sleepiness Scale. Additionally, free T and SHBG were associated with AHI in multivariable models among premenopausal women.

CONCLUSIONS

The present cross-sectional, population-based study observed sex-specific associations of androgens, E2, and SHBG with sleep apnea and daytime sleepiness. However, multivariable-adjusted analyses confirmed the impact of body composition and health-related lifestyle on the association between sex hormones and sleep.

Oxygen Uptake Efficiency Slope and Breathing Reserve, Not Anaerobic Threshold, Discriminate Between Patients With Cardiovascular Disease Over Chronic Obstructive Pulmonary Disease

OBJECTIVES

The study sought to compare the relative discrimination of various cardiopulmonary exercise testing (CPX) variables between cardiac and respiratory disease.

BACKGROUND

CPX testing is used in many cardiorespiratory diseases. However, discrimination of cardiac and respiratory dysfunction can be problematic. Anaerobic threshold (AT) and oxygen-uptake to work-rate relationship (VO2/WR slope) have been proposed as diagnostic of cardiac dysfunction, but multiple variables have not been compared.

METHODS

A total of 73 patients with chronic obstructive pulmonary disease (COPD) (n = 25), heart failure with reduced ejection fraction (HFrEF) (n = 40), or combined COPD and HFrEF (n = 8) were recruited and underwent CPX testing on a bicycle ergometer. Following a familiarization test, each patient underwent a personalized second test aiming for maximal exercise after ∼10 min. Measurements from this test were used to calculate area under the receiver-operator characteristic curve (AUC).

RESULTS

Peak VO2 was similar between the 2 principal groups (COPD 17.1 ± 4.6 ml/min/kg; HFrEF 16.4 ± 3.6 ml/min/kg). Breathing reserve (AUC: 0.91) and percent predicted oxygen uptake efficiency slope (OUES) (AUC: 0.87) had the greatest ability to discriminate between COPD and HFrEF. VO2/WR slope performed significantly worse (AUC: 0.68). VO2 at the AT did not discriminate (AUC for AT as percent predicted peak VO2: 0.56). OUES and breathing reserve remained strong discriminators when compared with an external cohort of healthy matched controls, and were comparable to B-type natriuretic peptide.

CONCLUSIONS

Breathing reserve and OUES discriminate heart failure from COPD. Despite it being considered an important determinant of cardiac dysfunction, the AT could not discriminate these typical clinical populations while the VO2/WR slope showed poor to moderate discriminant ability. (Identifying an Ideal Cardiopulmonary Exercise Test Parameter [PVA]; NCT01162083).

[Cardiopulmonary exercise testing in chronic obstructive pulmonary disease (COPD) - breath-functional characterization and disease severity assessment]

COPD is a heterogeneous disease with a wide range of clinical phenotypes and breath-functional dysfunctions. Cardiopulmonary exercise testing (CPET) allows describing all component parts of breathing and determining exercise capacity and the mechanisms of exercise limitation. From these aspects 64 COPD patient stages II, III and IV according to the conventional GOLD classification were examined by means of CPET to evaluate whether CPET can provide a better functional characterization of COPD than the standard investigation procedures in pulmonary practice.We could show that in pulmonary practice CPET is safely and effectively practicable in stable COPD patients of all GOLD stages. This method allowed a clinical and prognostic disease severity assessment of all patients, proving important differences of peak oxygen uptake in each GOLD stage, so that patients in spite of identical GOLD disease severity were to be assigned to different prognostic groups according CPET criteria. Furthermore, we found relevant differences of individual breath-functional patterns in exercise, which can neither be objectified nor be prognosticated by standard investigation procedures at rest.Therefore CPET allows, aside from an objective clinical and prognostic disease severity assessment, also a breath-functional evaluation in a subtly way in COPD patients reflecting the multidimensional background of the disease with variable dysfunctions in pulmonary ventilation, gas exchange, circulation and muscular function as well as associated cardio vascular comorbidities. The breath-functional phenotyping of the COPD patient seems to be meaningful in particular for an individualised therapy management.

Physiology of oxygen uptake kinetics: Insights from incremental cardiopulmonary exercise testing in the Study of Health in Pomerania

BACKGROUND

Cardiopulmonary exercise testing allows for assessment of cardiac and respiratory limitation, but is often affected by patient effort. Indices of oxygen kinetics, including the oxygen uptake efficiency slope (OUES), oxygen uptake-work-rate slope (VO2-WR slope) and the heart rate-oxygen uptake slope (HR-VO2 slope) are relatively effort independent but may be affected by patient characteristics. The objective of this study is to identify the impact of factors, such as age, gender, body size, respiratory function, smoking and beta-blockade on these parameters, as well as generate predictive equations.

METHODS

1708 volunteers from the population-based Study of Health in Pomerania underwent an incremental bicycle exercise protocol. Markers of oxygen kinetics were calculated. Participants with structural heart disease, echocardiographic or lung function pathology were excluded, leaving 577 males and 625 females. Age, height, weight, smoking, forced expiratory volume in 1 s (FEV1) and beta-blockers were analysed for their influencing power by gender. Quantile regression analysis determined the reference equations for each parameter.

RESULTS

Age, gender, height, weight and FEV1 (but not percent predicted FEV1) are strongly related to OUES. Participants using beta-blockers and male smokers had significantly lower OUES values. VO2-WR slope was minimally affected by age, gender, weight and FEV1. Gender, height, weight and beta-blocker use, but not FEV1 and smoking status, were related to the HR-VO2 slope whilst age was only related in females.

CONCLUSIONS

Markers of oxygen kinetics are differentially affected by patient characteristics. This study provides normal reference values for these variables thereby facilitating interpretation of oxygen uptake kinetics in health and disease.

Agreement of different methods for assessing sleep characteristics: a comparison of two actigraphs, wrist and hip placement, and self-report with polysomnography

OBJECTIVE

To assess the agreement of sleep parameters measured by two actigraphs (SOMNOwatch plus, ActiGraph GT3X+) at two different placements (wrist, hip) and of self-reported sleep with polysomnography (PSG).

METHODS

We estimated agreement with PSG for total sleep time (TST), sleep onset latency (SOL), wake after sleep onset (WASO), number of awakenings after sleep onset (NASO), and sleep efficiency (SE%) for 100 participants of the general population, aged 18-75 years by judging mean differences to PSG and intervals of agreement using Bland-Altman plots.

RESULTS

Mean difference to PSG for TST was 8.3 min (95% confidence intervals [CI] -7.4; 24.1) for SOMNOwatch plus (wrist), 39.8 min (95% CI 24.3; 55.3) for self-report, -79.0 min (95% CI -89.0; -68.9) for SOMNOwatch plus (hip), and -81.1 min (95% CI -91.9; -70.4) for GT3X+ (hip), respectively. The width of intervals of agreement differed with the placement of the devices. Mean differences to PSG were higher for hip-based measurements compared with wrist placement for most parameters.

CONCLUSIONS

Agreement of sleep parameters assessed by actigraphy with PSG differs with the placement of the device and is limited for hip-based measurements. Agreement of self-report with PSG is comparable to that of actigraphy for some parameters.