***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: To more systematic ally evaluate the effect of respiratory muscle rest on indices of ventilatory function , nine out patients with stable , severe COPD were treated with nasal pressure-support ventilation delivered via a nasal ventilatory support system ( BiPAP , Respironics , Inc ) for 2 h a day for 5 consecutive days . An additional eight control patients were treated with sham-BiPAP .  Maximum inspiratory pressure ( MIP ) , maximum expiratory pressure ( MEP ) , maximum voluntary ventilation ( MVV ) , arterial blood gas values , Borg dyspnea score , dyspnea-associated functional impairment scales , and distance walked in 6 min were measured in subjects prior to and following the week-long trial . Nasal BiPAP produced a 66.3 + /- 6 percent reduction in peak integrated diaphragmatic electromyographic ( EMG ) activity . There were no statistically significant changes in MIP , MEP , MVV , arterial pH , PaCO2 , or PaO2 or in objective measures of functional impairment from dyspnea in either group after ventilator or sham treatment . However , nasal BiPAP reduced the Borg category score during resting , spontaneous breathing from 2.0 + /- 0.4 to 0.7 + /- 0.3 ( p < 0.01 ) after 5 days of treatment . In contrast , sham BiPAP-treated patients had no change in their dyspnea score , which was 1.8 + /- 0.4 and 1.3 + /- 0.4 before and after sham treatment , respectively . Nasal BiPAP also increased distance walked in 6 min from 780 + /- 155 to 888 + /- 151 ft ( p < 0.01 ) ( 23,400 + /- 4,650 to 26,640 + /- 4,530 cm ) ( p < 0.01 ) , whereas sham-BiPAP had no effect ( 768 + /- 96 and 762 + /- 106 ft [ 23,040 + /- 2,880 and 22,860 + /- 3,180 cm ] ) before and after sham treatment , respectively ) . In conclusion , these results indicate that nasal pressure-support ventilation , delivered via nasal BiPAP , improves exercise capacity and reduces dyspnea over the short term in selected out patients with stable severe COPD . Whether such short-term improvement can be sustained merits further study The aim of this study was to compare the haemodynamic effects of a 45-min session of two modalities of non-invasive positive pressure ventilation ( nPPV ) , by means of cardiac echo-Doppler and right heart catheterization , in chronic obstructive lung disease ( COPD ) patients with chronic respiratory insufficiency . Fourteen patients with stable COPD ( 11 males , mean age 62.9 + /- 9.8 years ) underwent right heart catheterization using a floating Gr and jean catheter and simultaneous echo-Doppler measurements before and during two r and omly applied 45-min ventilatory sessions , consisting of nasal intermittent positive pressure ventilation in assist/control mode ( nIPPV ) and nasal pressure support ventilation ( nPSV ) .  Blood gases improved significantly during both modalities of ventilation . A significant increase during ventilatory sessions was found in invasive pulmonary right atrial pressure and cardiac output . A statistically significant decrease was found in the flow velocity peak of the superior vena cava and hepatic vein , and in systodiastolic flow velocity integral of the superior vena cava and hepatic vein . The inferior vena cava collapsibility index also decreased significantly during both ventilations . Right atrium diameter and area significantly decreased while right ventricular diameter significantly increased . The echo-Doppler cardiac output decreased significantly while systolic pulmonary artery pressure increased . A short session of both nIPPV and nPSV even without PEEP can induce significant haemodynamic changes in patients with stable COPD . Two-dimensional Doppler echocardiography is a non-invasive device with sufficient reliability to monitor the haemodynamic effects of nPPV . Further studies are needed to assess the effects of nPPV on vascular peripheral flows Two previous uncontrolled studies have suggested that noninvasive mechanical ventilation ( NIMV ) in patients with hypercapnic chronic obstructive pulmonary disease ( COPD ) improves arterial blood gas tensions by decreasing lung hyperinflation with the consequent reduction in inspiratory loads and changes in ventilatory pattern . The aim of this r and omised placebo-controlled study was to determine whether these mechanisms play a pivotal role in the effects of NIMV on arterial blood gases .  Thirty-six stable hypercapnic COPD patients were r and omly allocated to NIMV or sham NIMV . A 2-week run-in period was followed by a 3-week study period , during which ventilation was applied 3 h·day−1 , 5 days a week . Arterial blood gases , spirometry , lung volumes , and respiratory mechanics were measured before and after application of NIMV . Patients su bmi tted to NIMV showed changes ( mean ( 95 % confidence interval ) ) in daytime arterial carbon dioxide tension ( Pa , CO2 ) and arterial oxygen tension of −1.12 ( −1.52–−0.73 ) kPa ( −8.4 ( −11.4–−5.5 ) mmHg ) and 1.14 ( 0.70–1.50 ) kPa ( 8.6 ( 5.3–11.9 ) mmHg ) , respectively . Total lung capacity , functional residual capacity ( FRC ) and residual volume were found to be reduced by 10 ( 7–13 ) , 25 ( 18–31 ) , and 36 (27–45)% of their predicted value , respectively , whereas forced expiratory volume in one second and forced vital capacity increased by 4 ( 1.5–6.9 ) and 9 (5–13)% pred , respectively . Tidal volume ( VT ) increased by 181 ( 110–252 ) mL. All of the above changes were significant compared with sham NIMV . Changes in Pa , CO2 were significantly related to changes in dynamic intrinsic positive end-expiratory pressure , inspiratory lung impedance , VT and FRC . It was concluded that the beneficial effects of noninvasive mechanical ventilation could be explained by a reduction in lung hyperinflation and inspiratory loads STUDY OBJECTIVES To determine the 1-year efficacy of noninvasive positive pressure ventilation ( NPPV ) added to long-term oxygen therapy ( LTOT ) in patients with stable severe COPD . PATIENT SELECTION AND METHODS : We prospect ively r and omized 52 patients with severe COPD ( FEV(1 ) < 45 % ) to either NPPV plus " st and ard care " ( 96 % patients with LTOT ) or to st and ard care alone ( 93 % patients with LTOT ) . The outcomes measured included the following : rate of acute COPD exacerbations ; hospital admissions ; intubations ; and mortality at 3 months , 6 months , and 12 months . The patients were also evaluated at 3 months and 6 months for dyspnea using the Medical Research Council and Borg scales , gas exchange , hematocrit , pulmonary function , cardiac function with echocardiogram , and neuropsychological performance . RESULTS One-year survival was similar in both groups ( 78 % ) . The number of acute exacerbations was similar at all time points in patients receiving NPPV , compared with control subjects . The number of hospital admissions was decreased at 3 months in the NPPV group ( 5 % vs 15 % of patients , p < 0.05 ) , but this difference was not seen at 6 months ( 18 % vs 19 % , respectively ) . The only beneficial differences were observed in the Borg dyspnea rating , which dropped from 6 to 5 ( p < 0.039 ) , and in one of the neuropsychological tests ( psychomotor coordination ) for the NPPV group at 6 months . CONCLUSIONS Our study indicates that over 1 year , NPPV does not affect the natural course of the disease and is of marginal benefit in out patients with severe COPD who are in stable condition We evaluated the physiologic effects of pressure support ventilation by nasal route ( NPSV ) in eight patients with severe stable COPD and chronic hypercapnia who were r and omly su bmi tted to 2-h sessions of NPSV  both with a portable ventilator ( Respironics BIPAP device ) and with a st and ard ventilator ( Bird 6400ST device ) at an inspiratory airway pressure of 22 cm H2O . Two sessions with each ventilator were performed using an FIO2 of 0.21 in each patient on two consecutive days . One patient did not tolerate either form of ventilation . Comparison of spontaneous with BIPAP ventilation showed a significant improvement in pH , PaCO2 , and PaO2 . Ventilatory pattern assessed by a respiratory inductive plethysmograph showed a significant increase in minute ventilation ( VE ) , VT , and Ttot . Integrated surface diaphragmatic EMG activity measured only during BIPAP device ventilation decreased from that measured during spontaneous breathing . Similar changes in blood gases and ventilatory pattern were observed during ventilation by the Bird 6400ST except for VT/Ti ratio , which significantly increased . Comparison of baseline with measurements performed 12 h after the whole cycle of treatment showed a significant increase in pH and VE and a decrease in PaCO2 . We conclude that short-term NPSV may be useful in improving respiratory pattern and blood gases in stable COPD patients with chronic hypercapnia Chronic obstructive pulmonary disease ( COPD ) patients with chronic ventilatory failure ( CVF ) are more likely to develop exacerbations , which are an important determinant of health-related quality of life ( HRQL ) . Long-term noninvasive positive-pressure ventilation ( NPPV ) has been proposed in addition to long-term oxygen therapy ( LTOT ) to treat CVF but little information is available on its effects on HRQL and re source consumption . Therefore , the current authors undertook a 2-yr multicentric , prospect i ve , r and omised , controlled trial to assess the effect of NPPV+LTOT on : 1 ) severity of hypercapnia ; 2 ) use of healthcare re sources , and 3 ) HRQL , in comparison with LTOT alone . One hundred and twenty-two stable hypercapnic COPD patients on LTOT for ≥6 months were consecutively enrolled . After inclusion and 1-month run-in , 90 patients were r and omly assigned to NPPV+LTOT  ( n=43 ) or to LTOT alone ( n=47 ) . Arterial blood gases , hospital and intensive care unit ( ICU ) admissions , total hospital and ICU length of stay and HRQL were primary outcome measures ; survival and drop-out rates , symptoms ( dyspnoea and sleep quality ) and exercise tolerance were secondary outcome measures . Follow-up was performed at 3-month intervals up to 2 yrs . Lung function , inspiratory muscle function , exercise tolerance and sleep quality score did not change over time in either group . By contrast the carbon dioxide tension in arterial blood on usual oxygen , resting dyspnoea and HRQL , as assessed by the Maugeri Foundation Respiratory Failure Question naire , changed differently over time in the two groups in favour of NPPV+LTOT  . Hospital admissions were not different between groups during the follow-up . Nevertheless , overall hospital admissions showed a different trend to change in the NPPV+LTOT ( decreasing by 45 % ) as compared with the LTOT group ( increasing by 27 % ) when comparing the follow-up with the follow-back periods . ICU stay decreased over time by 75 % and 20 % in the NPPV+LTOT and LTOT groups , respectively . Survival was similar . Compared with long-term oxygen therapy alone , the addition of noninvasive positive-pressure ventilation to long-term oxygen therapy in stable chronic obstructive pulmonary disease patients with chronic ventilatory failure : 1 ) slightly decreased the trend to carbon dioxide retention in patients receiving oxygen at home and 2 ) improved dyspnoea and health-related quality of life . The results of this study show some significant benefits with the use of nocturnal , home noninvasive positive-pressure ventilation in patients with chronic ventilatory failure due to advanced chronic obstructive pulmonary disease patients . Further work is required to evaluate the effect of noninvasive positive-pressure ventilation on reducing the frequency and severity of chronic obstructive pulmonary disease exacerbation Evidence that noninvasive intermittent positive-pressure ventilation ( NiIPPV ) improves exercise capacity in chronic obstructive pulmonary disease ( COPD ) is limited . The effectiveness of different ventilators in this setting has not been studied . Three bilevel pressure support ventilators ( Bipap S/T 30 , Nippy2 and Vpap II ST ) , applied via a mouthpiece , were compared during submaximal treadmill exercise in eight subjects with COPD . Subjects walked to exhaustion with each of the ventilators and while breathing through the mouthpiece alone , in r and om order . In addition , four unencumbered walks were performed . The unencumbered distance ( mean±sd ) walked was 259±123 m. With the mouthpiece alone this decreased to 211±96 m and fell further to 145±76 m with NiIPPV . There was no difference between the br and s of ventilator . At the break-point of exercise , significant increases were seen in tidal volume and minute ventilation in the ventilator walks compared with the mouthpiece alone . Noninvasive intermittent positive-pressure ventilation increased ventilation but did not improve exercise capacity in the subjects in this study . No significant differences were 
    Output:
    
Lung hyperinflation and diaphragmatic work of breathing were reduced in a nonr and omised subset .
HRQOL and dyspnoea , the least studied outcomes , showed improvement with bilevel NIPPV .
In a subset of individuals on maximal medical treatment regimes for severe stable chronic obstructive pulmonary disease , bilevel noninvasive positive pressure ventilation may have an adjunctive role in the management of chronic respiratory failure through attenuation of compromised respiratory function and improvement in health-related outcomes