***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: STUDY OBJECTIVES Recently , we demonstrated significantly improved baroreflex sensitivity ( BRS ) and autonomic balance after 31 % supplemental oxygen ( SuppO2 ) in resting patients with chronic obstructive pulmonary disease ( COPD ) . In order to investigate whether peripheral arterial stiffness changes may play a role , we evaluated changes in peripheral arterial stiffness and BRS after SuppO2 . DESIGN Single blinded crossover design . SETTING Pulmonary exercise testing laboratory . PARTICIPANTS Seventy subjects with moderate to severe COPD . INTERVENTIONS We measured arterial vascular stiffness using the augmentation index via contour analysis of the radial pulse obtained from applanation tonometry .  BRS was derived using the sequence method before and after treatments with compressed air ( CA ) and 30 % SuppO2 in 70 individuals with COPD via a counterbalanced crossover design . RESULTS Paired t-tests indicated significant differences in oxygen saturation ( SaO2 ) following SuppO2 when compared to CA ( mean 96.0+/-2.0 % SuppO2 versus mean 92.6+/-3.6 % CA , P<0.001 ) . BRS was significantly greater following SuppO2 compared to CA ( mean 3.5+/-2.3 ms/mmHg SuppO2 versus mean 3.1+/-2.1 CA ms/mmHg , P<0.03 ) . Vascular stiffness was significantly increased with SuppO2 when compared with CA ( mean 13.3+/-6.1 % SuppO2 versus mean 10.8+/-4.9 % CA , P<0.001 ) . CONCLUSIONS Our findings indicate that oxygen supplementation ameliorates BRS by changes in vasomotor activity . The amelioration of the BRS into a more normal range is a move towards the restoration of more normal physiology Background : Conventional pulmonary rehabilitation programs improve exercise tolerance but have no effect on pulmonary function in patients with chronic obstructive pulmonary disease ( COPD ) . The role of controlled breathing using respiratory biofeedback during rehabilitation of patients with COPD remains unclear . Objectives : To compare the effects of a conventional 4-week pulmonary rehabilitation program with those of rehabilitation plus controlled breathing interventions . Methods : A r and omized controlled trial was performed . Pulmonary function ( FEV1 ) , exercise capacity ( 6-min walking distance , 6MWD ) , health-related quality of life ( chronic respiratory question naire , CRQ ) and cardiac autonomic function ( rMSSD ) were evaluated . Results : Forty COPD patients ( mean ± SD age 66.1 ± 6.4 , FEV1 45.9 ± 17.4 % predicted ) were r and omized to rehabilitation ( n = 20 ) or rehabilitation plus controlled breathing ( n = 20 ) . There were no statistically significant differences between the two groups regarding the change in FEV1 ( mean difference –0.8 % predicted , 95 % CI –4.4 to 2.9 % predicted , p = 0.33 ) , 6MWD ( mean difference 12.2 m , 95 % CI –37.4 to 12.2 m , p = 0.16 ) , CRQ ( mean difference in total score 0.2 , 95 % CI –0.1 to 0.4 , p = 0.11 ) and rMSSD ( mean difference 2.2 ms , 95 % CI –20.8 to 25.1 ms , p = 0.51 ) . Conclusions : In patients with COPD undergoing a pulmonary rehabilitation program  , controlled breathing using respiratory biofeedback has no effect on exercise capacity , pulmonary function , quality of life or cardiac autonomic function BACKGROUND & OBJECTIVES Practice of breathing exercises like pranayama is known to improve autonomic function by changing sympathetic or parasympathetic activity . Therefore , in the present study the effect of breathing exercises on autonomic functions was performed in young volunteers in the age group of 17 - 19 yr . METHODS A total of 60 male undergraduate medical students were r and omly divided into two groups : slow breathing group ( that practice d slow breathing exercise ) and the fast breathing group ( that practice d fast breathing exercise ) . The breathing exercises were practice d for a period of three months . Autonomic function tests were performed before and after the practice of breathing exercises . RESULTS The increased parasympathetic activity and decreased sympathetic activity were observed in slow breathing group , whereas no significant change in autonomic functions was observed in the fast breathing group . INTERPRETATION & CONCLUSION The findings of the present study show that regular practice of slow breathing exercise for three months improves autonomic functions , while practice of fast breathing exercise for the same duration does not affect the autonomic functions Background Previous small studies suggested SBOT may be ineffective in relieving breathlessness after exercise in COPD . Methods 34 COPD patients with FEV1 < 40 % predicted and resting oxygen saturation ≥93 % undertook an exercise step test 4 times . After exercise , patients were given 4 l/min of oxygen from a simple face mask , 4 l/min air from a face mask ( single blind ) , air from a fan or no intervention .  Results Average oxygen saturation fell from 95.0 % to 91.3 % after exercise . The mean time to subjective recovery was 3.3 minutes with no difference between treatments . The mean Borg breathlessness score was 1.5/10 at rest , rising to 5.1/10 at the end of exercise ( No breathlessness = 0 , worst possible breathlessness = 10 ) . Oxygen therapy had no discernable effect on Borg scores even for 14 patients who desaturated below 90 % . 15 patients had no preferred treatment , 7 preferred oxygen , 6 preferred the fan , 3 preferred air via a mask and 3 preferred room air . Conclusions This study provides no support for the idea that COPD patients who are not hypoxaemic at rest derive noticeable benefit from oxygen therapy after exercise . Use of air from a mask or from a fan had no apparent physiological or placebo effect OBJECTIVE Non-invasive mechanical ventilation ( NIMV ) has the potential to improve sympathovagal control of heart rate . The aim of this study was to investigate the acute effects of NIMV on heart rate variability ( HRV ) in chronic obstructive pulmonary disease ( COPD ) patients with hypercapnic respiratory failure ( HRF ) . METHODS In this prospect i ve study 28 COPD patients ( 64+/-10 years ) with HRF underwent electrocardiographic Holter monitorization .  Both time domain ( TD ) and frequency domain ( FD ) means of HRV analysis were measured for two hours before and during NIMV application . For the TD , mean-RR , SDNN , SDANN , SDNN index , RMSSD , pNN50 and HRV triangular index were measured . For FD , high frequency ( HF ) and low frequency ( LF ) were detected . To compare HRV parameters before and during bi-level positive airway pressure ( BiPAP ) application ; paired sample t test was used for normally distributed variables and Wilcoxon signed rank test was used for the variables that were not normally distributed . Pearson correlation test was used to analyze the correlation between HRV and blood gas parameters during BiPAP application . RESULTS High frequency power of HRV ( 39 ( 18 - 65 ) ms2 vs. 28 ( 12 - 50 ) ms2 , p<0.05 ) , HRV triangular index ( 9 ( 3 - 17 ) units vs. 6 ( 2 - 13 ) units , p<0.05 ) and pNN50 ( 59 % ( 13 - 110 ) vs. 42 % ( 5 - 84 ) , p<0.05 ) , were higher during NIMV than before noninvasive mechanical ventilation . CONCLUSIONS We think that NIMV may improve heart rate variability indices of parasympathetic modulation of heart rate in COPD cases with HRF and decrease arrhythmic potential Objectives Chronic obstructive pulmonary disease ( COPD ) is associated with cardiac autonomic nervous system dysregulation . This study evaluates the effects of interval hypoxic training on cardiovascular and respiratory control in patients with mild COPD . Methods In 18 eucapnic normoxic mild COPD patients ( age 51.7 ± 2.4 years , mean ± SEM ) , r and omly assigned to either training or placebo group , and 14 age-matched healthy controls ( 47.7 ± 2.8 years ) , we monitored end-tidal carbon dioxide , airway flow , arterial oxygen saturation , electrocardiogram , and continuous noninvasive blood pressure at rest , during progressive hypercapnic hyperoxia and isocapnic hypoxia to compare baroreflex sensitivity to hypoxia and hypercapnia before and after 3 weeks of hypoxic training . In double-blind fashion , both groups received 15 sessions of passive intermittent hypoxia ( training group ) or normoxia ( placebo group ) . For the hypoxia group , each session consisted of three to five hypoxic ( 15–12 % oxygen ) periods ( 3–5 min ) with 3-min normoxic intervals . The placebo group inhaled normoxic air . Results Before training , COPD patients  showed depressed baroreflex sensitivity , as compared with healthy individuals , without evident chemoreflex abnormalities . After training , in contrast to placebo group , the training group showed increased ( P < 0.05 ) baroreflex sensitivity up to normal levels and selectively increased hypercapnic ventilatory response ( P < 0.05 ) , without changes in hypoxic ventilatory response . Conclusion Eucapnic normoxic mild COPD patients already showed signs of cardiovascular autonomic abnormalities at baseline , which normalized with hypoxic training . If confirmed in more severe patients , interval hypoxic training may be a therapeutic strategy to rebalance early autonomic dysfunction in COPD patients Background —It is well established that a depressed baroreflex sensitivity may adversely influence the prognosis in patients with chronic heart failure ( CHF ) and in those with previous myocardial infa rct ion . Methods and Results —We tested whether a slow breathing rate ( 6 breaths/min ) could modify the baroreflex sensitivity in 81 patients with stable ( 2 weeks ) CHF ( age , 58±1 years ; NYHA classes I [ 6 patients ] , II [ 33 ] , III [ 27 ] , and IV [ 15 ] ) and in 21 controls .  Slow breathing induced highly significant increases in baroreflex sensitivity , both in controls ( from 9.4±0.7 to 13.8±1.0 ms/mm Hg , P < 0.0025 ) and in CHF patients ( from 5.0±0.3 to 6.1±0.5 ms/mm Hg , P < 0.0025 ) , which correlated with the value obtained during spontaneous breathing ( r = + 0.202 , P = 0.047 ) . In addition , systolic and diastolic blood pressure decreased in CHF patients ( systolic , from 117±3 to 110±4 mm Hg , P = 0.009 ; diastolic , from 62±1 to 59±1 mm Hg , P = 0.02 ) . Conclusions —These data suggest that in patients with CHF  , slow breathing , in addition to improving oxygen saturation and exercise tolerance as has been previously shown , may be beneficial by increasing baroreflex sensitivity Introduction Non-invasive ventilation may improve autonomic modulation and ventilatory parameters in severely disabled patients . The aim of the present study was to evaluate the physiological influence of acute treatment with different levels of continuous positive airway pressure ( CPAP ) on the autonomic balance of heart and respiratory responses in patients with stable chronic obstructive pulmonary disease ( COPD ) and chronic heart failure ( CHF ) . Material s and methods A COPD group ( n = 10 ) , CHF group ( n = 8) and healthy subjects ( n = 10 ) were evaluated . The participants were r and omized to receive three different levels of CPAP on the same day : sham ventilation ( Sham ) , 5 cmH20 ( CPAP5 ) and 10 cmH20 ( CPAP10 ) for 10 min . Respiratory rate , end tidal carbon dioxide ( ETCO2 ) , peripheral oxygen saturation ( SpO2 ) , heart rate ( HR ) , blood pressure and heart rate variability in the time and frequency domains were measured during spontaneous breathing and under the sham , CPAP5 and CPAP10 conditions . Results All groups experienced a reduction in ETCO2 values during treatment with CPAP ( p < 0.05 ) . CPAP increased SpO2 and HR in the COPD group ( p < 0.05 ) . The COPD group also had lower RMSSD values during treatment with different levels of CPAP when compared to the control group ( p < 0.05 ) . In the CHF group , CPAP5 and CPAP10 increased the SDNN value ( p < 0.05 ) . CPAP10 reduced the SDNN value in the COPD group ( p < 0.05 ) . Conclusion The findings suggest that CPAP may cause improvements in the neural control of heart rate in patients with stable COPD and CHF . For each patient , the “ best CPAP level ” should be defined as the best respiratory response and autonomic balance STUDY OBJECTIVES Patients with COPD have an increased sympathetic modulation and reduced baroreflex sensitivity ( BRS ) . Therefore , we studied the effects of breathing 31 % supplemental oxygen ( SuppO(2 ) ) on autonomic modulation in a 
    Output:
    
The evidence synthesis revealed that a strong and moderate level evidence supported oxygen supplementation and slow breathing techniques , respectively , in significantly enhancing the baroreceptor sensitivity ( BRS ) values in patients with COPD .
The effect of the examined techniques on the heart rate variability and muscle sympathetic nerve activity was of a limited or inconsistent evidence .
The findings from this review suggest that oxygen supplementation and controlled breathing techniques have profound positive influence on the BRS in patients with COPD .
However , it is not fully clear whether these influence translates to any therapeutic benefit on the general AF of patients with COPD in the long term