Systematic Review of The Effect of High Pressure Ventilation Compared to Low Pressure Ventilation in Chronic Obstructive Pulmonary Disease Patients

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

Effect of Noninvasive Respiratory Strategies on Intubation or Mortality Among Patients With Acute Hypoxemic Respiratory Failure and COVID-19: The RECOVERY-RS Randomized Clinical Trial.

Importance Continuous positive airway pressure (CPAP) and high-flow nasal oxygen (HFNO) have been recommended for acute hypoxemic respiratory failure in patients with COVID-19. Uncertainty exists regarding the effectiveness and safety of these noninvasive respiratory strategies. Objective To determine whether either CPAP or HFNO, compared with conventional oxygen therapy, improves clinical outcomes in hospitalized patients with COVID-19-related acute hypoxemic respiratory failure. Design, Setting, and Participants A parallel group, adaptive, randomized clinical trial of 1273 hospitalized adults with COVID-19-related acute hypoxemic respiratory failure. The trial was conducted between April 6, 2020, and May 3, 2021, across 48 acute care hospitals in the UK and Jersey. Final follow-up occurred on June 20, 2021. Interventions Adult patients were randomized to receive CPAP (n = 380), HFNO (n = 418), or conventional oxygen therapy (n = 475). Main Outcomes and Measures The primary outcome was a composite of tracheal intubation or mortality within 30 days. Results The trial was stopped prematurely due to declining COVID-19 case numbers in the UK and the end of the funded recruitment period. Of the 1273 randomized patients (mean age, 57.4 [95% CI, 56.7 to 58.1] years; 66% male; 65% White race), primary outcome data were available for 1260. Crossover between interventions occurred in 17.1% of participants (15.3% in the CPAP group, 11.5% in the HFNO group, and 23.6% in the conventional oxygen therapy group). The requirement for tracheal intubation or mortality within 30 days was significantly lower with CPAP (36.3%; 137 of 377 participants) vs conventional oxygen therapy (44.4%; 158 of 356 participants) (absolute difference, -8% [95% CI, -15% to -1%], P = .03), but was not significantly different with HFNO (44.3%; 184 of 415 participants) vs conventional oxygen therapy (45.1%; 166 of 368 participants) (absolute difference, -1% [95% CI, -8% to 6%], P = .83). Adverse events occurred in 34.2% (130/380) of participants in the CPAP group, 20.6% (86/418) in the HFNO group, and 13.9% (66/475) in the conventional oxygen therapy group. Conclusions and Relevance Among patients with acute hypoxemic respiratory failure due to COVID-19, an initial strategy of CPAP significantly reduced the risk of tracheal intubation or mortality compared with conventional oxygen therapy, but there was no significant difference between an initial strategy of HFNO compared with conventional oxygen therapy. The study may have been underpowered for the comparison of HFNO vs conventional oxygen therapy, and early study termination and crossover among the groups should be considered when interpreting the findings. Trial Registration isrctn.org Identifier: ISRCTN16912075