***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: Empirical treatment of patients with amyotrophic lateral sclerosis suggested that some modification of the classical downhill course occurred in nonfamilial cases during administration of guanidine hydrochloride in dosages of at least 10 mg per kilogram per day for three months or more . A controlled study is reported in 24 patients assigned r and omly to  guanidine doses of 2 or 25 mg per kilogram per day . By six months the group receiving the larger dose had more stable disease and lower mortality , but the number of stable cases lost significance by 10 months and no patient showed any improvement . Any short-term benefit in ALS from the administration of guanidine must be balanced against possible major side effects , including acute paralysis and bone marrow depression . Also , a relatively benign course without any treatment is more likely than was thought in the past Impairment of pulmonary function is a major prognostic indicator in amyotrophic lateral sclerosis ( ALS ) . Forced vital capacity ( FVC ) and maximal voluntary ventilation ( MVV ) decline linearly and are commonly used to assess disease progression . The aim of this study was to evaluate the usefulness of testing respiratory muscle strength in ALS with a novel test , sniff nasal pressure ( Pnsn ) , in parallel with more classic tests such as maximal inspiratory pressure ( PImax ) and maximal expiratory pressure ( PEmax ) . Sixteen patients with ALS were examined monthly over a period of 18 ± 10 months . At the time of inclusion in the study , values were normal for FVC ( 107 % of predicted value ) and MVV ( 87 % of predicted value ) but abnormally low for Pnsn ( 67 % of predicted value ) , PImax ( 69 % of predicted value ) , and PEmax ( 54 % of predicted value ) . Late in the course of ALS , all patients could perform Pnsn , whereas 6 could not perform PImax and 7 could not perform PEmax . The rate of deterioration was most often linear and similar for FVC ( −4.1 % of predicted value per month ) , MVV ( −4.3 % of predicted value per month ) , and Pnsn ( −4.2 % of predicted value per month ) . We conclude that Pnsn was the single respiratory test combining linear decline , sensitivity in mild disease , and feasibility in advanced disease . Being easy to perform and inexpensive , Pnsn appears well suited to assess the decline of respiratory muscle strength in ALS 
    Output:
    
This survival benefit was accompanied by an enhanced quality of life .
Non-invasive ventilation did not prolong survival in participants with poor bulbar function ( 21 participants ) , although it showed significant improvement in the mean symptoms domain of the Sleep Apnoea Quality of Life Index but not in the Short Form-36 Health Survey Mental Component Summary score .
AUTHORS ' CONCLUSIONS Evidence from a single r and omised trial of non-invasive ventilation in 41 participants suggests that it significantly prolongs survival and improves or maintains quality of life in people with ALS .
Survival and some measures of quality of life were significantly improved in the subgroup of people with better bulbar function , but not in those with severe bulbar impairment .