Sildenafil therapy lasting ≥ 12 weeks improves multiple clinical and hemodynamic outcomes in patients with PAH, but it appears to have no effect on mortality or serious adverse events. The long-term efficacy and safety of sildenafil therapy in PAH requires further study based on large and well-designed RCTs.

The role of non-invasive positive pressure ventilation (NIPPV) in acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is controversial. The aim of this study was to investigate whether NIPPV could prevent endotracheal intubation and decrease mortality rate in patients with ALI/ARDS. Randomized controlled trials (RCT) which reported endotracheal intubation and mortality rate in patients with ALI/ ARDS treated by NIPPV were identified in Pubmed, Medline, Embase, Central Cochrane Controlled Trials Register, Chinese National Knowledge Infrastructure, reference lists and by manual searches. Fixed-and random-effects models were used to calculate pooled relative risks. This meta-analysis included six RCT involving 227 patients. The results showed that endotracheal intubation rate was lower in NIPPV (95% confidence interval (CI): 0.44-0.80, z = 3.44, P = 0.0006), but no significant difference was found either in intensive care unit (ICU) mortality (95% CI: 0.45-1.07, z = 1.65, P = 0.10) or in hospital mortality (95% CI: 0.17-1.58, z = 1.16, P = 0.25). Only two studies discussed the aetiology of ALI/ARDS as pulmonary or extra-pulmonary, and neither showed statistical heterogeneity (I 2 = 0%, χ 2 = 0.31, P = 0.58), nor a significant difference in endotracheal intubation rate (95% CI: 0.35-9.08, z = 0.69, P = 0.49). In conclusion, the early use of NIPPV can decrease the endotracheal intubation rate in patients with ALI/ARDS, but does not change the mortality of these patients.