Pursed lips breathing (PLB) is used by a proportion of patients with chronic obstructive pulmonary disease (COPD) to alleviate dyspnea. It is also commonly used in pulmonary rehabilitation. Data to support its use in patients who do not spontaneously adopt PLB are limited. We performed this study to assess the acute effects of PLB on exercise capacity in nonspontaneously PLB patients with stable COPD. We performed a randomized crossover study comparing 6-min walk test (6MWT) at baseline without PLB with 6WMT using volitional PLB. Spirometry, maximal inspiratory and expiratory mouth pressures, and diaphragmatic excursion during tidal and vital capacity breathing using B-mode ultrasonography were measured at baseline and after 10 min of PLB. A Visual Analog Scale (VAS) assessed subjective breathlessness at rest, after 6MWT and after 6MWT with PLB. p 0.01 was considered significant. Mean + SD age of patients was 53.1 + 7.4 years. Forced expiratory volume in 1second was 1.1 + 0.4 L/min (38.4 + 13.2% predicted). Compared with spontaneous breathing, all but one patient with PLB showed a significant increment in 6MW distance (þ34.9 + 26.4 m; p ¼ 0.002). There was a significant reduction in respiratory rate post 6MWT with PLB compared with spontaneous breathing (À4.4 + 2.8 per minute; p ¼ 0.003). There was no difference in VAS scores. There was a significant correlation between improvement in 6MWT distance and increase in diaphragmatic excursion during forced breathing. The improvement was greater in patients who had poorer baseline exercise performance. PLB has an acute benefit on exercise capacity. Sustained PLB or short bursts of PLB may improve exercise capacity in stable COPD.

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Abstract Background: Avenues of treatment currently implemented for Covid-19 pandemic are largely supportive in nature. Non -availability of an effective antiviral treatment makes supportive care for acute hypoxic respiratory failure is the most crucial intervention. Highly contagious nature of Covid-19 had created stress and confusion among front line Health Care Workers (HCWs) regarding infectious risk of supportive interventions and best preventive strategies. Purpose: To analyze and summarize key evidence from published literature exploring the risk of transmission of Covid-19 related to common supportive care interventions in hospitalized patients and effectiveness of currently used preventive measures in hospital setting. Data Sources: Curated Covid-19 literature from NCBI Computational Biology Branch ,Embase and Ovid till May 20,2020.Longitudinal and reference search till June 28,2020 Study Selection: Studies pertaining to risk of infection to HCWs providing standard supportive care of hospitalized Covid-19 mainly focusing on respiratory support interventions.Indirect studies from SARS,MERS or other ARDS pathology caused by infectious agents based on reference tracking and snow ball search . Clinical, Healthy volunteer and mechanistic studies were included. Two authors independently screened studies for traditional respiratory supportive-care (Hypoxia management, ventilatory support and pulmonary toileting) related transmission of viral or bacterial pneumonia to HCWs. Data Extraction: Two authors (TK and SP) independently screened articles and verified for consensus. Quality of studies and level of evidence was assessed using Oxford Center for Evidence Based Medicine (OCEBM) , Newcastle - Ottawa quality assessment Scale for observational studies and Grading of Recommendations Assessment, Development and Evaluation (GRADE) system for grading evidence. Data Synthesis: 21 studies were eligible for inclusion. In 11 mechanistic studies, 7 were manikin based,1 was in the setting of GNB pneumonia ,2 were healthy volunteer study and 1 was heterogenous setting.Out of 10 clinical studies ,5 were case controlled and 6 were cohort studies. Risk of corona virus transmission was significantly high in HCWs performing or assisting endotracheal intubation or contact with respiratory secretion.(Moderate certainty evidence, GRADE B) Safety of nebulization treatment in corona virus pneumonia patients are questionable(Low certainty evidence, GRADE C).Very low certainty evidence exist for risk of transmission with conventional HFNC (GRADE D) and NIV (GRADE D),CPR (GRADE D),Bag and mask ventilation(GRADE D).Moderate certainty evidence exist for protective effect of wearing a multilayered mask, gown , eye protection and formal training for PPE use (GRADE B).Low certainty evidence exist for transmission risk with bag and mask ventilation, suctioning before and after intubation and prolonged exposure (GRADE C).Certainty of evidence for wearing gloves,post exposure hand washing and wearing N 95 mask is low(GRADE C). Limitations: This study was limited to articles with English abstract. Highly dynamic nature of body of literature related to Covid-19, frequent updates were necessary even during preparation of manuscript and longitudinal search was continued even after finalizing initial search. Due to the heterogeneity and broad nature of the search protocol, quantitative comparisons regarding the effectiveness of included management strategies could not be performed. Direct evidence was limited due to poor quality and non-comparative nature of available Covid-19 reporting. Conclusions: Major risk factors for transmission of corona virus infection were, performing or assisting endotracheal intubation and contact with respiratory secretion. Risk of transmission with HFNC or NIV can be significantly decreased by helmet interface, modified exhalation circuit or placing a properly fitting face mask over patient interface of HFNC. Evidence for risk of transmission with CPR, suctioning before or after intubation or bag and mask ventilation of very low certainty. Significant protective factors are Formal training for PPE use, consistently wearing mask, gown and eye protection. Primary Funding Source: None Disclosure: None of the authors have any conflict of interest to disclose.

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