Treatment of MDR, pre-XDR, XDR and rifampicin-resistant tuberculosis or in case of intolerance to at least rifampicin in Austria, Germany and Switzerland - Amendment to the 2022 consensus-based guideline: Tuberculosis in adulthood by the German Central Committee against Tuberculosis (DZK) on behalf of the German Respiratory Society (DGP) dated 19.09.2023.

Based on the assessment of new evidence, the World Health Organization (WHO) updated its guidelines for the treatment of drug-resistant tuberculosis (TB) in December 2022. The new recommendations and the latest study data made it necessary to update the existing guideline on the treatment of at least rifampicin- (RR-TB) for the German-speaking countries, replacing the respective chapters of the treatment guidelines published 2022. A shortened treatment of proven RR-TB and multidrug-resistant (MDR)-TB for at least 6 months using the fixed and non-modifiable drug combination of bedaquiline, pretomanid, linezolid, and moxifloxacin (BPaLM) is now also recommended for Austria, Germany, and Switzerland under certain conditions considering the existing barriers for the implementation of the new treatment regimen. For the treatment of pre-extensively drug-resistant (pre-XDR)-TB, an individualized treatment for 18 months continues to be the primary recommendation. The non-modifiable drug combination of bedaquiline, pretomanid, and linezolid (BPaL) may be used alternatively in selected pre-XDR-TB cases, provided that all prerequisites are met. The necessary requirements for using BPaLM and BPaL are presented in detail in this amendment to the consensus-based TB treatment guideline for adult patients.

Tuberculosis Case Detection and Guideline Adherence among Child Contacts in Switzerland: A Retrospective Observational Study.

BACKGROUND: Children exposed to a tuberculosis (TB) index case are at risk of TB infection and disease. OBJECTIVES: The aim of this study was to describe the proportion of child contacts who developed TB infection or disease after exposure and to assess the diagnostic pathways and adherence to current guidelines. METHODS: Retrospective observational study including children ≤16 years of age who had contact to a TB index case between January 2019 and July 2021. Analysis was stratified by age groups 0-4, 5-11, and 12-16 years. RESULTS: Of 401 TB-exposed children, data were available for 380 (95%). Of those, 7 (2%) were diagnosed with TB disease and 35 (9%) with TB infection. We identified several deviations in the management compared to recommendations in national Swiss guidelines: In the children aged 0-4 years, only 82% were examined with an immunodiagnostic test or a chest radiography within 2 weeks after last contact. Recommended prophylactic treatment was prescribed in 66% of the children only. In the children aged 5-11 years, 64% were tested with an immunodiagnostic test in a first examination and 75% in a second examination, 2 weeks and 2 months after last contact, respectively. CONCLUSIONS: Contact investigations of children exposed to a TB index case identified a significant proportion of children with TB infection and disease in a low TB incidence setting. We observed significant deviations from the guidelines in the contact investigations suggesting the need for improved implementation.

Health Preference Measures in Patients with Obstructive Sleep Apnea Syndrome Undergoing Continuous Positive Airway Pressure Therapy: Data from a Randomized Trial.

BACKGROUND: In patients with obstructive sleep apnea syndrome (OSAS), the preference-based, health-related quality of life in terms of utility has not been extensively studied. OBJECTIVE: To address this point, we compared the performance of different instruments assessing utility in patients with OSAS undergoing continuous positive airway pressure (CPAP) therapy. MATERIALS AND METHODS: Data of 208 patients with OSAS (28 women, mean ± SE age 54.4 ± 0.7 years, apnea-hypopnea index (AHI) 51.9 ± 1.8/h, Epworth sleepiness score 13.4 ± 0.2) participating in a randomized trial of different CPAP modalities over 2 years were analyzed. Evaluations included sleep studies, Epworth sleepiness scale, and several utility instruments that measure subjective health preference on a scale ranging from 1 (most preferred and perfect health) to 0 (least preferred and very poor health). RESULTS: After 2 years of CPAP therapy, the mean ± SE AHI was 6.7 ± 1.5/h and Epworth score 7.9 ± 0.4, both p < 0.001 versus baseline. Baseline utilities and changes (95% confidence interval) after 2 years of CPAP therapy were EuroQol 5-dimensions 0.79 ± 0.01, 0.02 (0.00-0.05, p = 0.064); short-form 6-dimension medical outcome questionnaire 0.72 ± 0.01, 0.06 (0.04-0.08, p < 0.001); Euro-thermometer visual analog scale 0.70 ± 0.01, 0.09 (0.07-0.12, p < 0.001); time trade-off 0.82 ± 0.01, 0.03 (0.01-0.06, p = 0.002); and standard gamble 0.82 ± 0.01, -0.01 (-0.03 to 0.02, p = 0.712). CONCLUSION: The short-form 6-dimensions questionnaire, the Euro-thermometer, and the time trade-off instruments reflected the major clinical improvements in OSAS, while the EuroQoL 5-dimensions and standard gamble tests were not sensitive to CPAP effects. These results indicate that the evaluation of utility of a treatment for OSAS depends critically on the instrument used, which is important from an individual and societal perspective.

Long-Term Mechanical Ventilation: Recommendations of the Swiss Society of Pulmonology.

Long-term mechanical ventilation is a well-established treatment for chronic hypercapnic respiratory failure (CHRF). It is aimed at improving CHRF-related symptoms, health-related quality of life, survival, and decreasing hospital admissions. In Switzerland, long-term mechanical ventilation has been increasingly used since the 1980s in hospital and home care settings. Over the years, its application has considerably expanded with accumulating evidence of beneficial effects in a broad range of conditions associated with CHRF. Most frequent indications for long-term mechanical ventilation are chronic obstructive pulmonary disease, obesity hypoventilation syndrome, neuromuscular and chest wall diseases. In the current consensus document, the Special Interest Group of the Swiss Society of Pulmonology reviews the most recent scientific literature on long-term mechanical ventilation and provides recommendations adapted to the particular setting of the Swiss healthcare system with a focus on the practice of non-invasive and invasive home ventilation in adults.

Classification of Sleep Apnea Severity by Electrocardiogram Monitoring Using a Novel Wearable Device.

Sleep apnea (SA) is a prevalent disorder diagnosed by polysomnography (PSG) based on the number of apnea-hypopnea events per hour of sleep (apnea-hypopnea index, AHI). PSG is expensive and technically complex; therefore, its use is rather limited to the initial diagnostic phase and simpler devices are required for long-term follow-up. The validity of single-parameter wearable devices for the assessment of sleep apnea severity is still debated. In this context, a wearable electrocardiogram (ECG) acquisition system (ECG belt) was developed and its suitability for the classification of sleep apnea severity was investigated using heart rate variability analysis with or without data pre-filtering. Several classification algorithms were compared and support vector machine was preferred due to its simplicity and overall performance. Whole-night ECG signals from 241 patients with a suspicion of sleep apnea were recorded using both the ECG belt and patched ECG during PSG recordings. 65% of patients had an obstructive sleep apnea and the median AHI was 21 [IQR: 7-40] h - 1 . The classification accuracy obtained from the ECG belt (accuracy: 72%, sensitivity: 70%, specificity: 74%) was comparable to the patched ECG (accuracy: 74%, sensitivity: 88%, specificity: 61%). The highest classification accuracy was obtained for the discrimination between individuals with no or mild SA vs. moderate to severe SA. In conclusion, the ECG belt provided signals comparable to patched ECG and could be used for the assessment of sleep apnea severity, especially during follow-up.

Clinical Applicability of a Textile 1-Lead ECG Device for Overnight Monitoring.

Even for 1-lead electrocardiography (ECG), single-use gel conductive electrodes are employed in a clinical setting. However, gel electrodes show limited applicability for long-term monitoring due to skin irritation and detachment. In the present study, we investigated the validity of a textile ECG-belt suitable for long-term measurements in clinical use. In order to assess the signal quality and validity of the ECG-belt during sleep, 242 patients (186 males and 56 females, age 52 (interquartile range 42-60) years, body mass index 29 (interquartile range 26-33) kg·m-2) with suspected sleep apnoea underwent overnight polysomnography including standard 1-lead ECG recording. The single intervals between R-peaks (RR-intervals) were calculated from the ECG-signals. We found a mean difference for average RR-intervals of -2.9 ms, a standard error of estimate of 0.39%, as well as a Pearson r of 0.91. Furthermore, we found that the validity of the ECG-belt decreases when lying on the side, which was potentially due to the fitting of the belt. In conclusion, the validity of RR-interval measurements using the ECG-belt is high and it may be further improved for future applications by optimizing wear fitting.

Applicability of a Textile ECG-Belt for Unattended Sleep Apnoea Monitoring in a Home Setting.

Sleep monitoring in an unattended home setting provides important information complementing and extending the clinical polysomnography findings. The validity of a wearable textile electrocardiography (ECG)-belt has been proven in a clinical setting. For evaluation in a home setting, ECG signals and features were acquired from 12 patients (10 males and 2 females, showing an interquartile range for age of 48-59 years and for body mass indexes (BMIs) of 28.0-35.5) over 28 nights. The signal quality was assessed by artefacts detection, signal-to-noise ratio, and Poincaré plots. To assess the validity, the data were compared to previously reported data from the clinical setting. It was found that the artefact percentage was slightly reduced for the ECG-belt from 9.7% ± 14.7% in the clinical setting, to 7.5% ± 10.8% in the home setting. The signal-to-noise ratio was improved in the home setting and reached similar values to the gel electrodes in the clinical setting. Finally, it was found that for artefact percentages above 3%, Poincaré plots are instrumental to evaluate the origin of artefacts. In conclusion, the application of the ECG-belt in a home setting did not result in a reduction in signal quality compared to the ECG-belt used in the clinical setting, and thus provides new opportunities for patient pre-screening or follow-up.

Autoadjusted versus fixed CPAP for obstructive sleep apnoea: a multicentre, randomised equivalence trial.

BACKGROUND: The obstructive sleep apnoea syndrome (OSAS) is conventionally treated by continuous positive airway pressure set at a fixed level (fCPAP). Automatic mask pressure adjustment (autoCPAP) is increasingly used during home therapy. We investigated whether autoCPAP is equivalent to fCPAP in improving sleepiness in patients with OSAS in the long-term. METHODS: In this multicentre equivalence trial, 208 patients with OSAS, with median Epworth sleepiness score (ESS) 13, apnoea/hypopnoea index 48.4/hour, were randomised to treatment with autoCPAP (5-15 mbar) or fCPAP (pressure set at the 90th percentile applied by autoCPAP during 2-4 weeks adaptation). Coprimary outcomes were changes in subjective and objective sleepiness from baseline to 2 years after treatment. Equivalence ranges were ±2 points in ESS and ±3 min sleep resistance time evaluated by recording responses to light signals. RESULTS: At 2 years, in the intention to treat analysis, the reduction in sleepiness versus pretreatment baseline was similar in patients using autoCPAP (n=113, mean ESS-change -6.3, 95% CI -7.1 to -5.5; sleep resistance time +8.3 min, +6.9 to +9.7) and fCPAP (n=95, mean ESS-change -6.2, 95% CI -7.0 to -5.3; sleep resistance time +6.3 min, +4.7 to +7.8). The 95% CI of difference in ESS-reduction between autoCPAP and fCPAP was -0.9 to +1.4 and the 95% CI of difference in increase in sleep resistance time was -2.6 to +1.0 min. Blood pressure reduction and OSAS-related costs were similar between groups. CONCLUSIONS: AutoCPAP and fCPAP are equivalent within prespecified ranges in improving subjective and objective sleepiness in patients with OSAS over the course of 2 years. Costs of these treatments are similar. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov NCT00280800.

Baseline predictors of adherence to positive airway pressure therapy for sleep apnea: a 10-year single-center observational cohort study.

BACKGROUND: Positive airway pressure (PAP) therapy is the standard treatment for obstructive sleep apnea syndrome (OSAS). OBJECTIVES: The aim of the current study was to determine operational long-term adherence to PAP and its predictors. METHODS: In a retrospective single-center observational cohort study, we analyzed all patients referred to our center with suspected OSAS between November 2001 and November 2011. Baseline results and last follow-up data of each patient were analyzed. Kaplan-Meier estimates of adherence and Cox proportional hazard regression for age, gender, Epworth sleepiness scale (ESS) scores, body mass index, apnea-hypopnea index (AHI) and oxygen desaturation index (ODI) were performed. Evolution of adherence was analyzed in yearly cohorts comparing the proportion of patients discontinuing PAP within 6 and 12 months. RESULTS: Of 4,638 referrals, 2,187 confirmed OSAS patients started PAP, 297 (14%) were referred out to other centers to follow-up, 42 (2%) died, and 92 (5%) no longer needed PAP. Of 1,756 patients, the median follow-up was 36 months [95% confidence interval (CI) 33.6-37.8], and adherence at 1, 5 and 10 years was 74 (CI 71-75; n = 1,028), 55 (CI 53-58; n = 281) and 51% (CI 48-55; n = 10), respectively. Adherence is associated with ESS score [hazard ratio (HR) 0.60; CI 0.47-0.78], ODI (HR 0.50; CI 0.32-0.77) and AHI (HR 0.56; CI 0.37-0.85). In yearly cohorts according to inclusion date, the absconder rate at 6 and 12 months was 20 (CI 18-22) and 27% (CI 25-30) for the first 8 years and improved to 10 (CI 7-15) and 14% (CI 10-19) for the last 2 years, respectively. CONCLUSIONS: Long-term adherence to PAP in OSAS is associated with baseline measures of disease severity. After 2009, an improvement in the adherence rate was observed.

Tuberculosis screening in immigrants from high-prevalence countries: interview first or chest radiograph first? A pro/con debate.

Immigration from high tuberculosis (TB) prevalence countries has a substantial impact on the epidemiology of TB in receiving countries with low TB incidence. Cross-border migration offers an ideal opportunity for active case finding that will result in a lower caseload in the host country and a reduced spread of disease to both the indigenous and migrant populations. Screening strategies can start 'offshore', thereby indirectly assisting and empowering public health systems in the source countries, or be performed at ports of entry with or without long-term engagement of 'onshore' facilities and systems to provide either preventive therapy or surveillance for reactivation of latent TB. The chest radiograph seems to be playing a key role in this process, but questions remain regarding when, where and in whom radiographs are best done for optimal yield and cost-effectiveness, and with what other tests they might best be combined to further increase the usefulness of transborder TB control.

Cognitive performance in high-altitude climbers: a comparative study of saccadic eye movements and neuropsychological tests.

Impairment of cognitive performance during and after high-altitude climbing has been described in numerous studies and has mostly been attributed to cerebral hypoxia and resulting functional and structural cerebral alterations. To investigate the hypothesis that high-altitude climbing leads to cognitive impairment, we used of neuropsychological tests and measurements of eye movement (EM) performance during different stimulus conditions. The study was conducted in 32 mountaineers participating in an expedition to Muztagh Ata (7,546 m). Neuropsychological tests comprised figural fluency, line bisection, letter and number cancellation, and a modified pegboard task. Saccadic performance was evaluated under three stimulus conditions with varying degrees of cortical involvement: visually guided pro- and anti-saccades, and visuo-visual interaction. Typical saccade parameters (latency, mean sequence, post-saccadic stability, and error rate) were computed off-line. Measurements were taken at a baseline level of 440 m and at altitudes of 4,497, 5,533, 6,265, and again at 440 m. All subjects reached 5,533 m, and 28 reached 6,265 m. The neuropsychological test results did not reveal any cognitive impairment. Complete eye movement recordings for all stimulus conditions were obtained in 24 subjects at baseline and at least two altitudes and in 10 subjects at baseline and all altitudes. Measurements of saccade performances showed no dependence on any altitude-related parameter and were well within normal limits. Our data indicates that acclimatized climbers do not seem to suffer from significant cognitive deficits during or after climbs to altitudes above 7,500 m. We demonstrated that investigation of EMs is feasible during high-altitude expeditions.

Eight months of continuous positive airway pressure (CPAP) decrease tumor necrosis factor alpha (TNFA) in men with obstructive sleep apnea syndrome.

OBJECTIVES: The aim of this study was to assess serum tumor necrosis factor alpha (TNFA) concentrations 8 months of continuous positive airway pressure (CPAP) therapy. DESIGN: This study used prospective, observational clinical trial. PATIENTS: Sixty-six patients with newly diagnosed sleep apnea syndrome (12 women, 54 men), age 52.3 ± 9.8 (mean ± SD) with a body mass index of 29.7 ± 4.4 and an apnea-hypopnea index of 39.7 ± 26.8, were studied. INTERVENTION: CPAP was administered for a mean of 7.8 ± 1.3 months. MEASUREMENTS AND RESULTS: TNFA concentrations using an ultrasensitive ELISA assay at baseline and follow-up. TNFA decreased in men with high (5.2 ± 1.7 h/night, -0.46 ± 1.1 ng/l, p = 0.001) and with low (2.5 ± 1.0 h/night -0.63 ± 0.77 ng/l, p = 0.001) adherence but not in women. Average number of hours of CPAP use correlated positively with delta TNFA (R (2) 0.08, p = 0.04) CONCLUSION: Long-term CPAP positively affects TNFA even in men with poor adherence to CPAP.

In-hospital survival paradox in patients with sleep apnea-A nation-wide nested case-control study.

BACKGROUND: Sleep apnea (SA) is a prevalent disorder characterized by recurrent events of nocturnal apnea originating from obstructive and/or central mechanisms. SA disrupts normal sleep and can lead to a series of complications when left untreated. SA results in intermittent hypoxia which has an impact on the cardio- and cerebrovascular system. Hospitalized patients with SA typically have a greater burden of comorbidity, a longer length of hospital stay, but may show an improvement of in-hospital mortality compared to patients without diagnosed SA. The reason for this survival benefit is controversial and we aimed to clarify this protective effect in the light of predictive factors including SA-associated comorbidities using a nation-wide hospitalization database. METHODS AND FINDINGS: Data were extracted from a nation-wide hospitalization database provided by the Swiss Federal Office for Statistics. Hospitalized patients with a SA co-diagnosis were extracted from the database together with a 1:1-matched control population without SA. Overall, 212'581 patients with SA were hospitalized in Switzerland between 2002 and 2018. Compared to the controls, SA cases had a longer median length of hospital stay (7 days; 95% CI: 3 to 15 vs. 4 days; 95% CI: 2 to 10) (p < 0.001) and a higher median number of comorbidities (8 comorbidities; IQR: 5 to 11 vs. 3 comorbidities; IQR: 1 to 6) (p < 0.001). The risk of in-hospital mortality was lower in the SA cases compared to the controls (OR: 0.73; 95% CI: 0.7 to 0.76; p < 0.001). SA was associated with a survival benefit in hospitalizations related to 28 of 47 conditions with the highest rate of in-hospital death. Sixty-three comorbidities were significantly over-represented in SA cases among which obesity, hypertension and anatomic nasal deviations were associated with a significant decrease of in-hospital mortality. CONCLUSIONS: Compared to matched controls, SA was associated with significant and relevant inpatient survival benefit in a number of most deadly conditions. Within SA-patients, associated comorbidities mostly correlated with a poorer prognosis, whereas obesity and hypertension were associated with an improved in-hospital mortality.

Nocturnal periodic breathing during acclimatization at very high altitude at Mount Muztagh Ata (7,546 m).

RATIONALE: Quantitative data on ventilation during acclimatization at very high altitude are scant. Therefore, we monitored nocturnal ventilation and oxygen saturation in mountaineers ascending Mt. Muztagh Ata (7,546 m). OBJECTIVES: To investigate whether periodic breathing persists during prolonged stay at very high altitude. METHODS: A total of 34 mountaineers (median age, 46 yr; 7 women) climbed from 3,750 m within 19-20 days to the summit at 7,546 m. During ascent, repeated nocturnal recordings of calibrated respiratory inductive plethysmography, pulse oximetry, and scores of acute mountain sickness were obtained. MEASUREMENTS AND MAIN RESULTS: Nocturnal oxygen saturation decreased, whereas minute ventilation and the number of periodic breathing cycles increased with increasing altitude. At the highest camp (6,850 m), median nocturnal oxygen saturation, minute ventilation, and the number of periodic breathing cycles were 64%, 11.3 L/min, and 132.3 cycles/h. Repeated recordings within 5-8 days at 4,497 m and 5,533 m, respectively, revealed increased oxygen saturation, but no decrease in periodic breathing. The number of periodic breathing cycles was positively correlated with days of acclimatization, even when controlled for altitude, oxygen saturation, and other potential confounders, whereas symptoms of acute mountain sickness had no independent effect on periodic breathing. CONCLUSIONS: Our field study provides novel data on nocturnal oxygen saturation, breathing patterns, and ventilation at very high altitude. It demonstrates that periodic breathing increases during acclimatization over 2 weeks at altitudes greater than 3,730 m, despite improved oxygen saturation consistent with a progressive increase in loop gain of the respiratory control system. Clinical trial registered with www.clinicaltrials.gov (NCT00514826).

Electrocardiographic alterations by pneumothorax: a case-control study with review of the literature.

BACKGROUND: Numerous ECG alterations due to pneumothorax have been reported. The objective of the study was to establish the presence of ECG changes associated with pneumothorax in the literature, and in a cohort of patients with proven pneumothorax compared with age- and sex-matched healthy controls. METHODS: A systematic review for ECG alterations associated with pneumothorax was performed. We then reviewed our hospital database for patients with pneumothorax and identified all patients with an ECG available at this time. The retrieved ECG alterations in the systematic review were identified in our pneumothorax patients and compared with a healthy sex- and age-matched control group. Accordingly, we calculated sensitivity and specificity for all alterations. RESULTS: Seventeen ECG alterations were found and defined from the systematic review. Our pneumothorax cohort consisted of 82 pneumothorax patients and 82 control patients. Specificity was mostly more than 90%, but sensitivities were low. Phasic R voltage (pneumothorax group 25.6% vs control group 1.2%), T-wave inversion (31.7% vs 2.4%), prolonged QTc (11.0% vs 2.4%), right axis deviation (14.6% vs 3.6%) and QRS voltage ratio in aVF/I >2 (41.5% vs 22.0%) were significantly more frequent in pneumothorax patients compared with controls. CONCLUSION: The sensitivity of published ECG signs in predicting pneumothorax in our cohort was low, which means that ECG findings are an unsuitable tool for pneumothorax screening. However, presence of these ECG signs might raise a suspicion of pneumothorax in patients presenting with dyspnoea, or unclear chest discomfort.

Impact of the new pulmonary hypertension definition on long-term mortality in patients with severe aortic stenosis undergoing valve replacement.

BACKGROUND: The new 2018 pulmonary hypertension (PH) definition includes a lower mean pulmonary artery pressure (mPAP) cut-off (>20 mmHg rather than ≥25 mmHg) and the compulsory requirement of a pulmonary vascular resistance (PVR) ≥3 Wood units (WU) to define precapillary PH. We assessed the clinical impact of the 2018 compared to the 2015 PH definition in aortic stenosis (AS) patients undergoing aortic valve replacement (AVR). METHODS: Severe AS patients (n = 487) undergoing pre-AVR right heart catheterization were classified according to the 2015 and 2018 definitions. Post-AVR mortality (median follow-up 44 months) was assessed. RESULTS: Based on the 2015 definition, 66 (13%) patients exhibited combined pre and postcapillary PH (CpcPH), 116 (24%) isolated post-capillary PH (IpcPH), 28 (6%) precapillary PH, and 277 (57%) no PH at all. Overall, 52 (11%) patients were reclassified: 23 no PH into IpcPH; 8 no PH into precapillary PH; 20 precapillary PH into no PH; 1 CpcPH into IpcPH. By the 2015 definition, only CpcPH patients displayed increased mortality, whereas by the 2018 definition, precapillary PH patients also experienced higher mortality than those without PH. Among the PH definition components, PVR ≥3 WU was the strongest predictor of death (hazard ratio > 4). CONCLUSIONS: In severe AS, a higher number of IpcPH patients are diagnosed by the 2018 definition, even though they have the same prognosis as those without PH. Patients with true precapillary PH are more accurately identified by the 2018 definition that includes a pulmonary vascular disease criterion, that is, PVR ≥3 WU, a strong mortality predictor.

New insights into ocular blood flow at very high altitudes.

Little is known about the ocular and cerebral blood flow during exposure to increasingly hypoxic conditions at high altitudes. There is evidence that an increase in cerebral blood flow resulting from altered autoregulation constitutes a risk factor for acute mountain sickness (AMS) and high-altitude cerebral edema (HACE) by leading to capillary overperfusion and vasogenic cerebral edema. The retina represents the only part of the central nervous system where capillary blood flow is visible and can be measured by noninvasive means. In this study we aimed to gain insights into retinal and choroidal autoregulatory properties during hypoxia and to correlate circulatory changes to symptoms of AMS and clinical signs of HACE. This observational study was performed within the scope of a high-altitude medical research expedition to Mount Muztagh Ata (7,546 m). Twenty seven participants underwent general and ophthalmic examinations up to a maximal height of 6,800 m. Examinations included fundus photography and measurements of retinal and choroidal blood flow, as well as measurement of arterial oxygen saturation and hematocrit. The initial increase in retinal blood velocity was followed by a decrease despite further ascent, whereas choroidal flow increase occurred later, at even higher altitudes. The sum of all adaptational mechanisms resulted in a stable oxygen delivery to the retina and the choroid. Parameters reflecting the retinal circulation and optic disc swelling correlated well with the occurrence of AMS-related symptoms. We demonstrate that sojourns at high altitudes trigger distinct behavior of retinal and choroidal blood flow. Increase in retinal but not in choroidal blood flow correlated with the occurrence of AMS-related symptoms.