Background: Chronic Obstructive Lung disease (COPD) is a progressive lung condition made from a group of diseases. It is characterised by productive cough, dyspnoea and reduced exercise tolerance. Exacerbations often lead to hospital admission, reduced QOL (QOL), a decline in lung function (LF) and inefficient ventilation. The disease currently challenges the NHS. Hypercapnic respiratory failure is treated with Non-Invasive Ventilation (NIV), domiciliary NIV is provided by a nasal or face mask and improves gaseous exchange. Pressure pre-set mode involves setting an Inspiratory Positive Airway Pressure (IPAP), there is debate regarding support of high inspiratory pressure ventilation being the effective at reducing partial pressure of carbon dioxide (PaCO2), however despite this low inspiratory positive pressures are recorded in primary studies the results have suggested although an improvement in
hypercapnia, results on clinical outcomes are not significant.
Objective: This systematic review explored the effects of low-pressure ventilation compared to high pressure ventilation on Lung Function, Arterial Blood Gas, Quality Of life , exercise tolerance, adherence, and identify any risks in patients with COPD on domiciliary NIV.
Methods Information Sources: Bibliographic databases were searched using keywords. CINHAL, MEDLINE, AMED via EBSCO Host and The Cochrane Library. Dates were search for English language studies between 1990 and 2017. Systematic reviews and meta-analysis reference lists were hand searched to assess for additional studies. Eligibility criteria: English language, randomised control trials. Excluded were observational studies, case studies, quasi experimental, narrative literature reviews and expert commentaries. Risk of bias was assessed using the Cochrane risk bias tool and the Critical
Appraisal tool for RCT’s were used to critically appraise the methods completed by one
reviewer.
Results: 1613 articles were assessed following deduplication. Titles and abstracts were screened against inclusion and exclusion criteria. 3 randomised control crossover trials were included in the systematic review and meta-analysis. 48 patients were Identified in total a meta-analysis was completed on the following outcomes, PaCO2, FEV1 and HRQOL. There was no significant difference in the effect of High-IPAP compared to low-IPAP in the reduction of PaCO2 (p=0.19) with a mean difference of -0.39Kpa (95% CI [-0.96, 0.19]) and results were homogenous (I2=0%, p=0.83). There was no significant difference in High-IPAP compared to low-IPAP in FEV1 (p=0.49) (95% CI 0.38 [-0.69,1.45]). Results favoured high IPAP for improvement of HRQOL however there was no significant difference between the effect of High-IPAP compared to Low-IPAP with a mean difference of 0.11 (95%CI [-1.17,0.95] p=0.77) there was no heterogeneity in results (I2=0%, P=0.59). A meta-analysis could not be completed on adherence, exacerbation and exercise tolerance as there was little or no data provided to complete a meta-analysis.
Conclusion: There was no significant difference in the effect of High-IPAP compared to lowIPAP in the reduction of PaCO2, FEV1, adherence and HRQOL. Further studies are required to assess the effects on exacerbation, adverse effects and exercise tolerance as there was little or no data available on these outcomes to perform a meta-analysis and explore further. The study has implications as it demonstrates that randomised control trials are required to investigate the effect of pressure to ensure patients are provided with effective treatment of and improve patient outcomes
