Inga Jarosch

Transcutaneous carbon-dioxide partial pressure trends during six-minute walk test in patients with very severe COPD

BACKGROUND Transcutaneous carbon-dioxide partial-pressure (TCPCO2) can be reliably measured and may be of clinical relevance in COPD. Changes in TCPCO2 and exercise-induced hypercapnia (EIH) during six-minute walk test (6MWT) need further investigation. We aimed (1) to define patterns of TCPCO2 trends during 6MWT and (2) to study determinants of CO2-retention and EIH. METHODS Sixty-two COPD patients (age: 63±8years, FEV1: 33±10%pred.) were recruited and TCPCO2 was recorded by SenTec digital-monitoring-system during 6MWT. RESULTS Half of patients (50%) exhibited CO2-retention (TCPCO2[Δ]>4mmHg); 26% preserved and 24% reduced TCPCO2. Nineteen (31%) patients presented EIH (TCPCO2>45mmHg). EIH was associated to higher baseline-PCCO2, worse FEV1, lower inspiratory-pressures, underweight/normal BMI, and pre-walk dyspnea. Stronger determinants of CO2-retention were FEV1 and pre-walk dyspnea, whereas baseline-PCCO2 and pre-walk dyspnea better predict EIH. CONCLUSIONS PCO2 response to 6MWT is highly heterogeneous; however, very low FEV1 and elevated baseline-PCCO2 together with pre-walk dyspnea increase the risk for CO2-retention and EIH. Overweight-BMI seems to carry a protective effect against EIH in very severe COPD.

Comparison of two- and six-minute walk tests in detecting oxygen desaturation in patients with severe chronic obstructive pulmonary disease - A randomized crossover trial.

The two-minute walk test (2MWT) is less well validated than the well-known six-minute walk test (6MWT) as a field walking test in patients with chronic obstructive pulmonary disease (COPD). The primary objective of this study was to compare the accuracy of the 2MWT to the 6MWT in detecting exercise-induced oxygen desaturation in patients with severe COPD. Twenty-six patients with COPD (age: 61 ± 10 years, forced expired volume in one second: 37 ± 10%) that were normoxemic at rest performed a 2MWT and a 6MWT under normal ambient conditions on two consecutive days in random order. Oxygen saturation, total walking distance, heart rate, breathing frequency, dyspnea, and leg fatigue were evaluated. Average walking distances were 150 m (95% confidence interval (95% CI): 134–165 m) and 397 m (95% CI: 347–447 m) for the 2MWT and 6MWT, respectively (r = 0.80, p < 0.0001). The difference in minimum oxygen saturation during the 2MWT (83%, 95% CI: 81–86%) and 6MWT (mean 82%, 95% CI: 80–84%) was not statistically different and the data strongly correlated between the groups (r = 0.81, p < 0.0001). Other measurements from the 6MWT, including heart rate, breathing rate, and levels of perceived exertion were also comparable in 2MWT. The 2MWT showed comparable validity in detecting exercise-induced oxygen desaturation in patients with severe COPD compared to the 6MWT.

Short-term Effects of Supplemental Oxygen on 6-Min Walk Test Outcomes in Patients With COPD: A Randomized, Placebo-Controlled, Single-blind, Crossover Trial

Background The acute effect of supplemental oxygen during exercise has been shown to differ largely among patients with COPD. It is unknown what factors influence oxygen response. Methods In a randomized, single‐blind fashion, 124 patients with COPD underwent one 6‐min walk test on supplemental oxygen (6MWTO2) and one 6‐min walk test on room air after a practice 6‐min walk test. Both gases were delivered via standard nasal prongs (2 L/min). For analyses, patients were stratified on the basis of PaO2 values and compared: (1) 34 patients with resting hypoxemia (HYX); (2) 43 patients with exercise‐induced hypoxemia (EIH); and (3) 31 patients with normoxemia (NOX). Results Oxygen supplementation resulted in an increase in the 6‐min walk distance in the total cohort (27 ± 42 meters; P < .001) and in the subgroups of HYX (37 ± 40 meters; P < .001) and EIH (28 ± 44 meters; P < .001) but not in the NOX subgroup (15 ± 43 meters; P = .065). Forty‐two percent of patients with HYX and 47% of patients with EIH improved their 6‐min walk distance to a clinically relevant extent (≥ 30 meters) by using oxygen. These oxygen responders were characterized by significantly lower 6‐min walk distance using room air compared with patients without a relevant response (306 ± 106 meters vs 358 ± 113 meters; P < .05). Although oxygen saturation was significantly higher during 6MWTO2 compared with the 6‐min walk test on room air in all 3 subgroups, it dropped to < 88% during 6MWTO2 in 73.5% of patients with HYX. Conclusions In contrast to patients with NOX, patients with HYX and EIH generally benefit from supplemental oxygen by increasing exercise capacity. However, less than one‐half of patients reached the threshold of clinically relevant improvements. These oxygen responders were characterized by significantly lower exercise capacity levels. Trial Registry ClinicalTrials.gov; No.: NCT00886639; URL: www.clinicaltrials.gov.

Similarities in the Computed Tomography Appearance in α1-Antitrypsin Deficiency and Smoking-Related Chronic Obstructive Pulmonary Disease in a Smoking Collective

Background: Emphysematous destruction of lung parenchyma visible in computed tomography (CT) can be attributed to chronic obstructive pulmonary disease (COPD) or to α1-antitrypsin deficiency (AATD). Objectives: We evaluated if visual semiquantitative phenotyping of CT data helps identifying individuals with AATD in a group of smokers with severe emphysema and airflow limitation. Method: n = 14 patients with AATD and n = 15 with COPD and a minimum of 10 pack years underwent CT, clinical assessment, and full-body plethysmography. The extent and type of emphysema as well as large and small airway changes were rated semiquantitatively for each lobe using a standardized previously published scoring system. Lastly, a final diagnosis for each patient was proposed. Results: AATD had a significantly lower mean emphysema score than COPD, with 8.9 ± 3.4 versus 11.9 ± 3.2 (p < 0.001), respectively. Within both groups, there was significantly more emphysema in the lower lobes (p < 0.05–0.001). The COPD group showed an upper- and middle-lobe predominance of emphysema distribution when compared to the AATD group (p < 0.001). Centrilobular (CLE) and panlobular (PLE) emphysema patterns showed a uniform distribution within both groups, with a CLE predominance in the upper lung and a PLE predominance in the lower lung regions. AATD and COPD both showed significantly more airway changes in lower lobes compared to upper lobes (p = 0.05–0.001), without significant differences between both groups. Conclusion: The typical emphysema distribution patterns seen on CT traditionally assigned to AATD and COPD were of little use in discriminating both entities. Also, airway changes could not contribute to a more precise differentiation. We conclude that a concise standardized phenotyping-driven approach to chest CT in emphysema is not sufficient to identify patients with AATD in a cohort of smokers with advanced emphysema.

Whole body vibration training in long-term (>1 year) lung transplant patients – A randomized, controlled trial

Background: Whole-body vibration training (WBVT) has been shown to be a feasible and effective exercise modality in patients directly following lung transplantation (LTx). Aim of this study was to investigate WBVT effects in long-term LTx patients (LTx>1year). Methods: 70 long-term LTx patients (mean duration since LTx: 5.7±4.5 years) participated in this randomized controlled trial. All patients performed a comprehensive pulmonary rehabilitation program of 3-weeks duration including a standardized endurance and strength training program on 5 days per week. On top, patients were randomized into squat training groups 3x/wk performing dynamic squat exercises for 4x2 min either on a side-alternating WBVT platform at high frequencies of 24-26 Hz (WBVT group) or for the same amount on the floor (control group, CON). Results: Patients in both groups reached a significant increase in 6-minute walk distance (WBVT: 44±44m versus CON: 22±34m) which was significantly superior in favor of the WBVT-group (delta: 22m, p=0.027). Also peak cycling work rate increased significantly more in the WBVT group (15±9W versus 10±9W, between-group difference: 5W, p=0.044). Furthermore, LTx patients who performed WBVT showed a significant increase in insulin-like growth factor (+18±49ng/ml) compared to control (-14±51ng/ml, between-group difference: 32ng/ml, p=0.035). Conclusion: Squat training on a vibration platform induced significantly higher improvements in exercise capacity compared to squat training on the floor. Therefore, WBVT seems to be an effective add-on exercise modality also in long-term LTx patients.

Accuracy of a transcutaneous carbon dioxide monitor during the 6-minute walk test in COPD patients - a pilot study

Background: Chronic respiratory failure can be associated with CO2 retention and hypercapnia during exercise in COPD patients. A continuously monitoring of transcutaneous CO2 levels (TcPCO2) may be useful to screen CO2 trends and to identify patients with exercise-induced hypercapnia (EIH). Objective: The aim of this study was to investigate the accuracy of the SenTec Digital Monitoring System (SDMS, SenTec AG, Therwil, Switzerland) during the 6-minute walk test (6MWT) in COPD patients. Methods: 10 COPD patients were enrolled in this prospective, pilot study. Capillary blood gases (CBG) from the earlobe were taken by the same investigator pre-6MWT and directly following 6MWT withTcPCO2 levels recorded simultaneously. To ensure a valid comparison between CBG and TcPCO2, values were taken at the same time point. An independent person set digital markers in the SenTec device concurrently with the taking of the CBG. Results: The agreement of PCO2 recording between CBG and SenTec device showed a very strong intra-class correlation coefficient for pre-walk (ICC=0.98, 95%CI: 0.93-0.99) and post-walk (ICC=0.98, 95CI: 0.73-0.99) values of the 6MWT (see Figure). Conclusion: Transcutaneously measured PCO2 values by the SDMS during 6MWT were highly accurate. The strong correlation with CBG and the continuous, non-invasive method could be advantageous to detect patients with EIH during the 6MWT.

Original Research: COPDShort-term Effects of Supplemental Oxygen on 6-Min Walk Test Outcomes in Patients With COPD: A Randomized, Placebo-Controlled, Single-blind, Crossover Trial

Background The acute effect of supplemental oxygen during exercise has been shown to differ largely among patients with COPD. It is unknown what factors influence oxygen response. Methods In a randomized, single‐blind fashion, 124 patients with COPD underwent one 6‐min walk test on supplemental oxygen (6MWTO2) and one 6‐min walk test on room air after a practice 6‐min walk test. Both gases were delivered via standard nasal prongs (2 L/min). For analyses, patients were stratified on the basis of PaO2 values and compared: (1) 34 patients with resting hypoxemia (HYX); (2) 43 patients with exercise‐induced hypoxemia (EIH); and (3) 31 patients with normoxemia (NOX). Results Oxygen supplementation resulted in an increase in the 6‐min walk distance in the total cohort (27 ± 42 meters; P < .001) and in the subgroups of HYX (37 ± 40 meters; P < .001) and EIH (28 ± 44 meters; P < .001) but not in the NOX subgroup (15 ± 43 meters; P = .065). Forty‐two percent of patients with HYX and 47% of patients with EIH improved their 6‐min walk distance to a clinically relevant extent (≥ 30 meters) by using oxygen. These oxygen responders were characterized by significantly lower 6‐min walk distance using room air compared with patients without a relevant response (306 ± 106 meters vs 358 ± 113 meters; P < .05). Although oxygen saturation was significantly higher during 6MWTO2 compared with the 6‐min walk test on room air in all 3 subgroups, it dropped to < 88% during 6MWTO2 in 73.5% of patients with HYX. Conclusions In contrast to patients with NOX, patients with HYX and EIH generally benefit from supplemental oxygen by increasing exercise capacity. However, less than one‐half of patients reached the threshold of clinically relevant improvements. These oxygen responders were characterized by significantly lower exercise capacity levels. Trial Registry ClinicalTrials.gov; No.: NCT00886639; URL: www.clinicaltrials.gov.

Grundlagen der nichtmedikamentösen Therapie

Die positive Wirkung pneumologischer Rehabilitation (PR) ist fur haufig auftretende chronische Erkrankungen der Atmungsorgane, wie z. B. der COPD, wissenschaftlich bereits gut belegt. In den letzten Jahren sind zunehmend auch seltene Lungenerkrankungen in den Fokus der Rehabilitationsforschung geruckt. Studien zeigen, dass eine Rehabilitation mit korperlichem Training auch fur diese Patienten einen positiven Effekt hat und sowohl die korperliche Leistungsfahigkeit als auch die Lebensqualitat verbessern kann. Um den Erfolg zu optimieren, sollten einzelne Module der PR modifiziert und auf die krankheitsspezifischen, individuellen Bedurfnisse des Patienten angepasst werden.