Patient engagement as a collaborative process in a large Dutch COVID-19 vaccination study (RECOVAC) - insight into the contribution of patient engagement and learnings for the future.

BACKGROUND: The need for patient engagement in health research has been increasingly acknowledged and accepted in recent years. However, implementation is still limited due to lack of evidence on its value and lack of guidance on how to implement patient engagement. This study aims to provide insight into the contribution of patient engagement in the RECOVAC project, which studied COVID-19 vaccination in kidney patients, and formulate concrete practice-based action perspectives for patient engagement. METHODS: We used a qualitative participatory mixed methods approach, based on the Patient Engagement Monitoring and Evaluation (PEME) framework. Patient engagement and data collection were based on the Reflexive Monitoring in Action (RMA) approach. Data collection included participant observations, open ended questionnaires and interactive reflection sessions. Qualitative analysis was done via a thematic approach. RESULTS: We have described the process of patient engagement systematically, provided insight in its value and found that there is a need for clear aims, expectations and preparations from the start of the engagement process. We have shown that reflection throughout the process is of utmost importance and the same applies to clear communication between researchers and patient representatives. By being part of the consortium patient representatives had direct access to information, straight from the source, on for example the vaccination schedule and medication availability and had indirect influence on decisions made by the National Institute for Public Health and the Environment (RIVM) on preventive measures and treatment against COVID-19. Having experienced patient representatives is important, otherwise training needs to be provided. We also found that patient engagement had impact on conduct and outcomes of research activities itself and may have impact on future research and patient engagement activities in general. CONCLUSION: Patient engagement has changed the course of the project. Concrete practice-based action perspectives have been formulated, which are already being implemented by the Dutch Kidney Patients Association (NVN). Studying patient engagement in a high pace project with high public interest has resulted in lessons learned and will help prepare and implement patient involvement in future research projects. CLINICAL TRIAL REGISTRATION: The RECOVAC studies in which the patient engagement took place are registered at clinicialtrial.gov (NCT04741386 registration date 2021-02-04, NCT04841785 registration date 2021-03-22 and NCT05030974 registration date 2021-08-20).

This article is about the extensive engagement of patients in a scientific research project and what that engagement adds to the project. Although researchers acknowledge the importance of engagement of patients in research projects, it is not happening very often, Because there is not enough scientific evidence on the value of patient engagement and not enough guidance for researcher on how to implement it in their research. We used the Patient Engagement Monitoring and Evaluation (PEME) framework and qualitative participatory mixed methods research to provide insight into patient involvement in the RECOVAC project, which studied COVID-19 vaccination in kidney patients. We also formulated practical guidance for researchers who want to engage patients in their research. We describe the process of patient engagement in the RECOVAC project; what went well and what could be improved. We found that it is important to prepare well, keep reflecting on the engagement process throughout the project with all stakeholders of the project, communicate clearly and have experienced patient representatives involved or have training available for them. Patient engagement had impact on the conduct and outcome of the research activities itself and on activities outside of the project (e.g., doctors changing their conversations with their patients). We can conclude that involving patients changed the project and its outcomes to better fit with the needs of patients. A guideline has been made and is already implemented by the Dutch Kidney Patients Association. The lessons learned from this project will help researchers involve patients in their future projects.

Can short-wavelength depleted bright light during single simulated night shifts prevent circadian phase shifts?

In single night shifts, extending habitual wake episodes leads to sleep deprivation induced decrements of performance during the shift and re-adaptation effects the next day. We investigated whether short-wavelength depleted (=filtered) bright light (FBL) during a simulated night shift would counteract such effects. Twenty-four participants underwent a simulated night shift in dim light (DL) and in FBL. Reaction times, subjective sleepiness and salivary melatonin concentrations were assessed during both nights. Daytime sleep was recorded after both simulated night shifts. During FBL, we found no melatonin suppression compared to DL, but slightly faster reaction times in the second half of the night. Daytime sleep was not statistically different between both lighting conditions (n = 24) and there was no significant phase shift after FBL (n = 11). To conclude, our results showed positive effects from FBL during simulated single night shifts which need to be further tested with larger groups, in more applied studies and compared to standard lighting.

[Evaluation of a structured smoking cessation program for primary care medicine]. / Evaluierung eines strukturierten Tabakentwöhnungsprogramms für die ärztliche Praxis.

BACKGROUND: Despite the fact that 9 of 10 general practitioners in Germany believe that smoking cessation is an important topic structured programs are only rarely offered to patients. Beside a lack of time and missing reimbursement, physician's limited treatment skills are frequent reasons for this observation. Therefore we aimed to develop a structured, easy to learn and time-effective smoking cessation program for the general practice. Evidence based treatment elements were combined and standardized by a step by step treatment guideline. METHODS: In a non-interventional observation we tested the program's integration in the daily routines of physicians, the rate of continuous tobacco abstinence after 12 weeks and both patient's and physician's satisfaction with the program and the medication. RESULTS: 44 physicians participated in the study. 184 patients were observed over a mean period of 12.8 weeks and were treated with an individually adapted nicotine replacement therapy for 10 weeks. At the end of treatment (12.1 weeks after the target quit date) 48.4% of the patients reported continuous abstinence. The combination of structured counseling with nicotine substitution in this program was easily implemented in doctor's practice, induced a high user satisfaction and a long usage of medication. The encouraging abstinence rate could have been influenced by selecting highly motivated patients, by offering structured and regular consultations at fixed intervals over the first weeks and by the treatment with the individually adapted nicotine substitution. CONCLUSION: This study shows an easy way to implement an individual and structured smoking cessation therapy in primary care medicine in Germany. Nevertheless, the results should be confirmed in larger cohorts and on a higher methodological level.

[Influence of nocturnal oxygen therapy on quality of life in patients with COPD and isolated sleep-related hypoxemia: a prospective, placebo-controlled cross-over trial]. / Einfluss der nächtlichen Sauerstofftherapie auf die Lebensqualität bei Patienten mit COPD und isolierter schlafbezogener Hypoxämie: Eine prospektive, plazebokontrollierte cross-over Studie.

BACKGROUND: In patients with COPD and isolated night time hypoxemia, oxygen administration has not shown any effects on life expectancy and the development of pulmonal arterial hypertension. The aim of the present pilot study was to investigate the influence of nocturnal oxygen therapy on the quality of life in daytime normoxemic COPD patients with nocturnal oxygen desaturations. PATIENTS AND METHODS: 19 patients with COPD, in a stable phase of the disease without need for oxygen supplementation under rest (PaO2 62.7 +/- 4.9 mmHg) and nocturnal hypoxemia (t90 = 55.5 +/- 33.4 % of registration time, mean SaO2 89.8 +/- 1.9 %, minimal SaO2 81.1 +/- 4.8 %) were randomly assigned to either oxygen or placebo treatment, both generated by identical concentrator devices. Each treatment period lasted 6 weeks, after six weeks a cross-over was performed by a technician. Quality of life was assessed before and at the end of each treatment period by the SF-36, Nottingham Health Profile and Saint George's Respiratory Questionnaire. RESULTS: Significant differences for the comparison of placebo and verum were only seen for the dimension sleep (NHP), all other dimensions showed no differences between placebo and oxygen. However, both placebo and oxygen improved the majority of the quality of life items significantly. CONCLUSIONS: The prescription of supplemental oxygen in COPD patients with isolated nocturnal hypoxemia in the present pilot study is not able to improve the quality of life within 6 weeks after initiation of therapy. It cannot, therefore, be generally recommended, but may be indicated in patients with a documented improvement of sleep quality.

[Locus of control belief is a predictor of CPAP-compliance in patients with obstructive sleep apnea syndrome]. / Die Kontrollüberzeugung ist ein Prädiktor für CPAP-Compliance bei obstruktivem Schlafapnoesyndrom1.

Approximately 25 % of all patients suffering from obstructive sleep apnea syndrome (OSAS) discontinue CPAP-therapy in long-term follow-up. This study was conducted to investigate if there are any predictors signaling low compliance prior to initiation of CPAP-therapy. We used an open label longitudinal cohort study at an University hospital in-patient Sleep laboratory setting. In 85 consecutive patients with a diagnosis of OSAS confirmed by polysomnography a CPAP-therapy was initiated. Prior to CPAP-titration the subjects were interviewed using standardized, validated questionnaires (Nottingham Health Profile, von Zerssen's Depression Scale, State Trait Anxiety Inventory, IPC-Scale). On follow up (mean 16 +/- 8 month) 66 patients were still using CPAP regularly, 19 individuals had discontinued the therapy. Data of both groups were compared. There were no significant differences in polysomnographic parameters before CPAP except apnea-hypopnea-index (users: 30.72 +/- 20.68, rejecters: 18.43 +/- 10.43) and mean oxygen saturation (users: 91.65 +/- 3.32, rejecters 93.63 +/- 1.86). Depression and anxiety levels were normal in both groups. The subjects who discontinued CPAP had a significantly less external control belief. Internal control belief was normal in all patients. It is suggested that individuals who discontinued CPAP could not be convinced of the necessity of CPAP by physicians or nurses due to their reduced external control belief. Identifying patients with diminished external control belief prior to prescription of a device might be useful. In selected subgroups, different methods of motivation to maintain long-term acceptance for CPAP-therapy seems to be necessary.

Obstructive sleep apnea syndrome: the effect of diabetes and autonomic neuropathy.

Several studies indicate an association between obstructive sleep apnea syndrome (OSAS) and diabetic autonomic neuropathy (DAN). Observed frequency of OSAS in diabetic patients with DAN varies between 26% and 30%. Excessive daytime sleepiness is one of the major clinical symptoms of sleep disordered breathing. Diabetics with autonomic neuropathy might have abnormal control of respiration during sleep, probably resulting in a reduced daytime sleepiness. We investigated the impact of autonomic diabetic neuropathy on clinical symptoms (e.g., daytime sleepiness, measured by Epworth Sleepiness Scale, ESS) in patients with suspected OSAS. We examined 196 patients suspected of sleep apnea (52 female, 144 male, mean age 58.7 yrs, mean BMI 30.57 kg/m2). All patients underwent overnight polysomnography and were tested for autonomic neuropathy by a method of measuring heart rate variabilty and heart rate response to the Valsalva maneuver, standing and deep breathing using a computerized data analysis system. Eighty diabetic subjects: 52 DAN-, 28 DAN+; 116 subjects without diabetes: 101 without autonomic neuropathy (AN), 15 AN+. The group of diabetics with DAN+ had a mean apnoea/hypopnea index (AHI) of 38.6/h, mean oxygen desaturation: 77.5%, mean ESS-Score: 9.86. Diabetic patients DAN-: mean AHI:30.4/h, mean oxygen desaturation: 79.3%, mean ESS-Score 9.73. Defining OSAS as AHI>5/h and ESS-Score>9, 46% of the diabetic patients DAN+ were positive, whereas in the DAN- group 61% met the criteria (non-diabetic patients without AN 50.5%; with AN: 60%). Although the group of diabetic patients with autonomic neuropathy had the lowest percentage of OSAS, statistical analysis showed no significance in comparisons between DAN-/DAN+ or diabetic/non-diabetic. In conclusion, although this study did not give statistical evidence, there is reason to assume that patients with diabetic autonomic neuropathy show fewer clinical symptoms of OSAS than those without it. The examination for OSAS might be indicated even without excessive daytime sleepiness because of elevated cardiovascular risk.

Driving simulator and neuropsychological [corrected] testing in OSAS before and under CPAP therapy.

Patients with obstructive sleep apnoea syndrome (OSAS) have an increased car accident rate. Investigations on accident frequency are based on case history, insurance reports and driving simulator studies. The present study combines neuropsychological testing of different attention aspects engaged in driving a car and driving simulation to evaluate a suitable instrument for assessing therapeutic effects of continuous positive airway pressure (CPAP). Driving simulator investigation and neuropsychological testing of alertness, vigilance and divided attention were performed in 31 patients with polysomnographically confirmed OSAS (apnoea-hypopnoea index 24.8+/-21.5.h(-1)) before, and 2 and 42 days after initiation of CPAP. Divided attention and alertness improved significantly during CPAP, whereas vigilance remained unchanged. However, accident frequency (OSAS before therapy: 2.7+/-2.0; 2 days after CPAP: 1.5+/-1.4; 42 days after CPAP: 0.9+/-1.3) and frequency of concentration faults (OSAS before therapy: 12.4+/-5.1; 2 days after CPAP: 6.5+/-3.9; 42 days after CPAP: 4.9+/-3.3) decreased in the simulated driving situation after 2 and 42 days of therapy. There was no relation between accident frequency, concentration faults and daytime sleepiness, as measured by the Epworth Sleepiness Scale, and polysomnographic or neuropsychological findings, respectively. In conclusion, the present results suggest that driving simulation is a possible benchmark parameter of driving performance in obstructive sleep apnoea syndrome patients.

[Driving simulator performance in patients with obstructive sleep apnea syndrome: what consequences for driving capability?]. / Fahrsimulatoruntersuchung bei Patienten mit obstruktivem Schlafapnoe-Syndrom: Konsequenzen für die Beurteilung der Fahrtüchtigkeit?

BACKGROUND AND OBJECTIVE: Patients with obstructive sleep apnea (OSA) have an increased accident risk. The German Society of Sleep Research and Sleep Medicine (DGSM) recommends for patients with OSA and daytime sleepiness that their driving ability should be re-established 6 weeks after the initiation of CPAP (continuous positive airway pressure), with documentation of therapeutic effects on daytime symptoms and performance. The present study was conducted to investigate whether an improvement of driving ability can be documented in neuropsychological tests and a simulated driving situation 14 days after the initiation of CPAP. PATIENTS AND METHODS: Driving simulation and neuropsychological tests of vigilance were conducted in 36 patients (36 males, aged 54 9 years) with OSAS before and 2 (n=23), 14 (n=18) and 42 days (n=17) after initiation of CPAP. RESULTS: Vigilance tests showed only slight changes under CPAP. Frequency of accidents during driving simulation was reduced after 14 days of CPAP, but a statistically remarkable decrease was achieved only on day 42. In contrast, concentration faults were reduced after 2 and 14 days of CPAP. CONCLUSIONS: In OSA-patients improvement of daytime performance in a simulated driving situation can be documented 14 days after initiation of CPAP. There is need for investigating larger cohorts of patients so that current recommendations for driving licensing can be modified and permission to drive can be given earlier.

GC: a review of the state-of-the-art column technologies for the determination of ppm to ppb levels of oxygenated, sulfur, and hydrocarbon impurities in C1-C5 hydrocarbon streams.

The determination of ppm to ppb levels of sulfur, oxygen-containing, and certain reactive hydrocarbons in bulk hydrocarbon feedstocks is important in the petroleum and petrochemical industry to minimize catalytic deactivation and improve product quality. Gas chromatography, coupled with selective or ultratrace universal detection (or both), is ideal in most cases for such analysis. However, to enhance selectivity and quantitation at the trace levels, optimized stationary phases are required. These phases are usually of the adsorbent type. This paper summarizes the performance of several state-of-the-art phases for the analyses of trace key hydrocarbons, sulfur, and oxygenated components.

Trace analysis of benzene, toluene, ethylbenzene and xylene isomers in environmental samples by low-pressure gas chromatography-ion trap mass spectrometry.

A rapid determination of benzene, toluene, ethylbenzene and the three xylene isomers (BTEX), including a nearly baseline separation of the xylene isomers in environmental samples within 1 min has been carried out using low-pressure gas chromatography-ion trap mass spectrometry (LP-GC-IT-MS). In order to evaluate the different parameters which may influence the performance of LP-GC-IT-MS, different column and mass spectral parameters were varied. Comparing LP-GC-IT-MS with the conventional equivalent, we obtained excellent detection limits as well as a good RSD of 8-13% in ition to a much shorter analysis time. In order to evaluate LP-GC-IT-MS for use in environmental samples, we determined BTEX in air.

[Treatment regulations and treatment limits: factors influencing clinical decision-making]. / Behandlungsgebot und Behandlungsbegrenzung: Einflussfaktoren klinischer Entscheidungsprozesse.

BACKGROUND: Providing or withholding of treatment is based on a variety of factors. We sought for criteria in clinical decision making and reviewed attitudes towards clinical intuition and the patient's will. METHODS: 503 physicians (25.6 % females; mean age 36.3) in 49 departments at nine hospitals of the universities Bochum and Magdeburg filled in a validated questionnaire. RESULTS: The most important factors in the decision to carry out a therapy were "international standards" and "own experience". The decision to omit a therapy was mainly influenced by the "patient's wish". Physicians with a higher status judged their own experience higher than young physicians, who considered the experience of colleagues more important. "Severe accompanying illnesses" and "multimorbidity" were the most frequently named reasons to withdraw a therapy. Intuitive decision-making was rare, especially in young physicians, although these decisions were seldom risky and often successful. CONCLUSIONS: A patient's will plays a prominent role in clinical decision making, especially in decisions to withdraw or to withhold treatment. Cost containment and research interest have been called less important, a remarkable response from research-based university hospitals. Also remarkable is the recognition and importance of clinical intuition in situations of complex or missing information. This important aspect is rarely discussed in the literature or in medical education. The widely voiced concern that priorities in clinical care are guided by scientific interest, financial or technical possibilities could not be confirmed.

[Providing or withholding treatment: the role of the patient's wish and priorities in palliative care]. / Behandlungsgebot und Behandlungsbegrenzung: Einfluss des Patientenwillens und Prioritäten in der palliativen Versorgung.

BACKGROUND AND OBJECTIVE: Medical law and ethics require that intervention be based on patients' wishes. However, in particular the presumed wish of the patient, is often difficult to establish. Discussions with patients may want to inform or influence the patient's wishes. We investigated how far clinical decisions recognize the patient's wishes and how the presumed wishes of the patient is established and respected. PATIENTS AND METHODS: 503 physicians (25.6 % women; mean age 36.3) in 49 departments of the universities Bochum and Magdeburg filled in a validated questionnaire. RESULTS: 86,2 % of the physicians questioned ranked the patient's wish as important or very important. However, 54,4 % tried to modify it. Advanced directives play the most important role when the patient is unable to communicate. Danger to life and suicide are reasons for clinical decisions against the patient's wishes. But it is the main reason to end a causal therapy in terminally ill patients, especially in experienced physicians' opinion. CONCLUSIONS: Patients will plays a prominent role in treatment decisions; Even more so, physicians follow patients' wishes when withholding or withdrawing treatment. Our study could not find out how widely information of the patient plays a role in altering the patient's wishes in a paternalistic manner. Given a relative unfamiliarity with advance directives, affirmative attitudes towards their recognition are remarkable. As far as palliative and comfort care for terminal patients is concerned, contrary to widely voiced concern, clinicians do not have priorities different from those used in hospice care.

[Inflammatory pseudopapilloma after recurring aspiration of fruit stones as rare differential diagnosis of bronchogenic cancer]. / Inflammatorische Pseudopapillome nach rezidivierender Obstkernaspiration als seltene Differenzialdiagnose des Bronchialkarzinoms.

We present the case of a 51-year old man with drug-resistant pneumonia in the upper right lobe, weight loss and a 50-pack year history of cigarette smoking who underwent bronchoscopy. By clinical and radiological findings bronchogenic cancer was assumed. Fiberbronchoscopy showed an exophytic tumor-like mass obliterating the right upper lobe. Biopsies revealed an epithelial pseudopapillomatous tumor with multiple mucosal dysplasia and metaplasia. A second bronchoscopy in order to remove the lesion revealed a foreign body embedded in the tissue which could be removed easily. The foreign body proved to be a cherry stone, after its removal pneumonia resolved completely. In the same patient this lesion was recurrent one year later after aspiration of a grape seed. We present this case to emphasize the relationship between foreign body aspiration and inflammatory pseudopapilloma as a sequela of the inflammatory insult provoked by foreign bodies. Bronchoscopy is mandatory and may obviate misdiagnosis and thoracotomy. The use of inhaled and systemic steroids can be used to facilitate successful endoscopic extraction.

[Estimation of accident risk in obstructive sleep apnea syndrome (OSAS) by driving simulation]. / Abschätzung des Unfallrisikos bei obstruktivem Schlafapnoe-Syndrom (OSAS) durch Fahrsimulation.

Abstract. Patients with obstructive sleep apnea syndrome (OSAS) have an accident rate between two and seven times higher than normals. Investigations on accident frequency are based on case history, insurancy reports, and driving simulator investigations. The present controlled study was planned to test whether an increased accident risk could be demonstrated in patients with OSAS before and on CPAP (continuous positive airway pressure)-therapy using the driving simulator C.A.R. Driving simulator performance was investigated in 31 patients with polysomnographically confirmed OSAS (apnea-hypopnea-index 24.8 +/- 21.5/h) before, 2 and 42 days after initiation of CPAP and was compared to 10 healthy controls in whom OSAS was excluded by polysomnography. Driving simulator performance was significantly worse in OSAS as compared to normals especially in terms of accident frequency (OSAS: 2.7 +/- 2.0, controls: 1.3 +/- 1.5, p < 0.05) and concentration faults (OSAS: 12.4 +/- 5.1, controls: 7.1 +/- 3.2, p < 0.01). On CPAP accident frequency (OSAS before therapy: 12.4 +/- 5.1, 2 days CPAP: 1.5 +/- 1.4, p < 0.01; 42 days CPAP: 0.9 +/- 1.3, p < 0.001) and frequency of concentration faults (OSAS before therapy: 12.4 +/- 5.1, 2 days CPAP: 6.5 +/- 3.9, p < 0.001; 42 days CPAP: 4.9 +/- 3.3, p < 0.001) could be lowered significantly both in the short and medium term of therapy. The driving simulator C.A.R. is an adequate tool for the evaluation of an increased accident risk in OSAS-patients and demonstrates the efficiency of CPAP-therapy.

[Obstructive sleep apnea syndrome: a cardiovascular risk factor?]. / Das obstruktive Schlafapnoe-Syndrom: Ein kardiovaskulärer Risikofaktor?

INTRODUCTION: Obstructive sleep apnea syndrome (OSAS) is frequently associated with cardiovascular disease. We investigated endothelium-dependent and endothelium-independent nitric oxide-mediated vasodilatory function in normotensive patients with OSAS using the hand vein compliance technique. PATIENTS AND METHODS: Dose-response curves to the endothelium-dependent vasodilator bradykinin were obtained in 23 male subjects with OSAS and 12 male control subjects of comparable age, height, and weight. RESULTS: Mean (+/- SD) maximum dilation (Emax) to bradykinin was significantly lower in OSAS patients than in controls (59.8 +/- 26.0 vs. 94.8 +/- 9.5%, p < 0.0001). Mean vasodilation with nitroglycerin was not diminished in the OSAS group (90.7 +/- 30.5 vs. 100.3 +/- 12.9% in controls; n.s.). In 11 OSAS patients, a follow-up investigation was performed after at least 2 months of treatment with nasal continuous positive airway pressure (CPAP): Emax to bradykinin rose from 54.5 +/- 19.2% to 111.5 +/- 25.1% after treatment (p < 0.001). Mean vasodilation to nitroglycerin was unchanged. CONCLUSIONS: These results suggest that endothelium-dependent nitric oxide-mediated vasodilation is impaired in patients with OSAS due to an impaired function in the endothelial cells. This impairment is reversible with CPAP treatment.

[Expectations and satisfaction of patients during inpatient treatment]. / Erwartungen und Zufriedenheit von Patienten während eines stationären Krankenhausaufenthaltes.

PURPOSE: Aim of the study was to examine the expectations of patients at the beginning and the satisfaction at the end of a hospital stay. The hospital settings were standardised. METHODS: 510 patients on the cardiological ward were asked to fill in a questionnaire on the first and last day of their stay. RESULTS: The admitted patients stated clear expectations in respect of the hospital facilities and staff. The most important aspects for the patients were the qualification of staff and the time physicians and nurses would devote to the patient, and the medical and technical equipment of the hospital. Beds per room, food, length and costs of the stay were less important in patients' expectations. On the day of discharge, the patients were very satisfied with the staff and medical equipment, in contrast to a low satisfaction regarding additional fees and the number of beds per room (three). CONCLUSIONS: Since cost-benefit is a basic need in running a hospital today, financial resources should be enhanced in the spheres which are equally medically important for fulfilling the expectations of the patients. Therefore, the number of staff and the qualification of the medical professionals should be financed instead of supporting architectural and room design. Accordingly, the patients' main criteria for choosing a hospital is the medical equipment provided and the qualification of the medical staff. In conclusion, these aspects should be publicized for meaningful decision-making. Medical professionals should be encouraged to inspire competence and to spend as much time as possible with each individual patient.

[The impact of different definitions of hypoxemia on the relation between awake pulmonary pressure and hypoxemia during sleep in patients with COPD]. / Der Einfluss verschiedener Hypoxämiedefinitionen auf die Beziehung zwischen Pulmonalisdruck im Wachzustand und Hypoxämie im Schlaf bei COPD.

BACKGROUND: Sleep related hypoxemia (SRH) in chronic obstructive pulmonary disease (COPD) can be easily detected by pulse-oximetry and may contribute to the development of pulmonary hypertension (PH). Since several parameters for the quantification of SRH are in use, we investigated which of these parameters has the strongest relation to the awake pulmonary arterial pressure (PAP) and is able to distinguish between patients without and with PH. PATIENTS AND METHODS: 44 COPD-patients (awake PaO2 > or = 60 mm Hg) were investigated. PAP at rest (PAP; pathological threshold > 20 mm Hg) and under physical exercise (PAPB; p.t. > 28 mm Hg) were determined during daytime by Swan-Ganz-catheter. To quantify the degree of SRH the following parameters of nocturnal pulse-oximetry were used: mean nocturnal oxygen saturation (SaO2 m; p.t. < 90%), nadir SaO2 (SaO2 min; p.t. < 85%), and mean time of SaO2 < or = 90% in relation to total time of registration (t90; p.t. > 30%). Linear correlations and regressions as Chi 2-respectively Fisher-test were used for statistical analysis (p < 0.05). RESULTS: Generally there was only a weak relation between PAP and SRH. The best linear correlation at rest respectively under physical exercise was found between PAP and SaO2 min (r = -0.529 resp. -0.541, p < 0.001). Using the above defined thresholds for PAP and SaO2 patients could be most precisely separated into those without and with PH using SaO2 min with a threshold for the pathological range of < 85% (p = 0.030 resp. 0.002). t90 with a threshold > 30%, however, had a much worse selectivity (p = 0.487 resp. 0.057). CONCLUSIONS: In COPD-patients with SRH the closest relation can be found between nadir SaO2 and PAP resp. PAPB. Furthermore nadir SaO2 (< 85%) could more precisely separate patients into those without and with pulmonary hypertension than t90. The overall weak relation between nocturnal oxygenation and pulmonary hypertension shows, however, that other factors such as daytime PaO2, hypercapnia or emphysema are involved in the development of pulmonary hypertension in COPD.