Background: Acute type two respiratory failure (AT2RF) is characterized by high carbon dioxide levels (PaCO2 >6kPa). Non-invasive ventilation (NIV), the current standard of care, has a high failure rate. High flow nasal therapy (HFNT) has potential additional benefits such as CO2 clearance, the ability to communicate and comfort. The primary aim of this systematic review is to determine whether HFNT in AT2RF improves 1) PaCO2, 2) clinical and patient-centred outcomes and 3) to assess potential harms. Methods: We searched EMBASE, MEDLINE and CENTRAL (January 1999-January 2021). Randomised controlled trials (RCTs) and cohort studies comparing HFNT with low flow nasal oxygen (LFO) or NIV were included. Two authors independently assessed studies for eligibility, data extraction and risk of bias. We used Cochrane risk of bias tool for RCTs and Ottawa-Newcastle scale for cohort studies. Results: From 727 publications reviewed, four RCTs and one cohort study (n=425) were included. In three trials of HFNT vs NIV, comparing PaCO2 (kPa) at last follow-up time point, there was a significant reduction at four hours (1 RCT; HFNT median 6.7, IQR 5.6 – 7.7 vs NIV median 7.6, IQR 6.3 – 9.3) and no significant difference at 24-hours or five days. Comparing HFNT with LFO, there was no significant difference at 30-minutes. There was no difference in intubation or mortality. Conclusions: This review identified a small number of studies with low to very low certainty of evidence. A reduction of PaCO2 at an early time point of four hours post-intervention was demonstrated in one small RCT. Significant limitations of the included studies were lack of adequately powered outcomes and clinically relevant time-points and small sample size. Accordingly, systematic review cannot recommend the use of HFNT as the initial management strategy for AT2RF and trials adequately powered to detect clinical and patient-relevant outcomes are urgently warranted.
Background: Acute type two respiratory failure (AT2RF) is characterized by high carbon dioxide levels (PaCO2 >6kPa). Non-invasive ventilation (NIV), the current standard of care, has a high failure rate. High flow nasal therapy (HFNT) has potential additional benefits such as CO2 clearance, the ability to communicate and comfort. The primary aim of this systematic review is to determine whether HFNT in AT2RF improves 1) PaCO2, 2) clinical and patient-centred outcomes and 3) to assess potential harms. Methods: We searched EMBASE, MEDLINE and CENTRAL (January 1999-January 2021). Randomised controlled trials (RCTs) and cohort studies comparing HFNT with low flow nasal oxygen (LFO) or NIV were included. Two authors independently assessed studies for eligibility, data extraction and risk of bias. We used Cochrane risk of bias tool for RCTs and Ottawa-Newcastle scale for cohort studies. Results: From 727 publications reviewed, four RCTs and one cohort study (n=425) were included. In three trials of HFNT vs NIV, comparing PaCO2 (kPa) at last follow-up time point, there was a significant reduction at four hours (1 RCT; HFNT median 6.7, IQR 5.6 – 7.7 vs NIV median 7.6, IQR 6.3 – 9.3) and no significant difference at 24-hours or five days. Comparing HFNT with LFO, there was no significant difference at 30-minutes. There was no difference in intubation or mortality. Conclusions: This review identified a small number of studies with low to very low certainty of evidence. A reduction of PaCO2 at an early time point of four hours post-intervention was demonstrated in one small RCT. Significant limitations of the included studies were lack of adequately powered outcomes and clinically relevant time-points and small sample size. Accordingly, systematic review cannot recommend the use of HFNT as the initial management strategy for AT2RF and trials adequately powered to detect clinical and patient-relevant outcomes are urgently warranted.
IntroductionAcute respiratory failure is a common clinical condition accounting for nearly 116 000 admissions in the UK hospitals. Acute type 2 respiratory failure is also called acute hypercapnic respiratory failure (AHRF) and characterised by an elevated arterial CO2 level of >6 kPa due to pump failure. Acute exacerbation of chronic obstructive pulmonary disease is the most common cause of AHRF. High-flow nasal therapy (HFNT) is a new oxygen delivery system that uses an oxygen-air blender to deliver flow rates of up to 60 L/min. The gas is delivered humidified and heated to the patient via wide-bore nasal cannula.Methods and analysisWe hypothesised that HFNC as the initial oxygen administration method will reduce the number of patients with AHRF requiring non-invasive ventilation in patients at 6 hours post intervention when compared with low-flow nasal oxygen (LFO). A randomised single-centre unblinded controlled trial is designed to test our hypothesis. The trial will compare two oxygen administration methods, HFNT versus LFO. Patients will be randomised to one of the two arms if they fulfil the eligibility criteria. The sample size is 82 adult patients (41 HFNT and 41 LFO) presenting to the emergency department.Ethics and disseminationEthical approval was obtained from the Office for Research Ethics Committees Northern Ireland (REC reference: 20/NI/0049). Dissemination will be achieved in several ways: (1) the findings will be presented at national and international meetings with open-access abstracts online and (2) in accordance with the open-access policies proposed by the leading research funding bodies we aim to publish the findings in high-quality peer-reviewed open-access journals.Trial registration numberThe trial was prospectively registered at the clinicaltrials.gov registry (NCT04640948) on 20 November 2020.
(1) Background: High-flow nasal therapy (HFNT) has shown several benefits in addressing respiratory failure. However, the quality of evidence and the guidance for safe practice are lacking. This survey aimed to understand HFNT practice and the needs of the clinical community to support safe practice. (2) Method: A survey questionnaire was developed and distributed to relevant healthcare professionals through national networks in the UK, USA and Canada; responses were collected between October 2020 and April 2021. (3) Results: In the UK and Canada, HFNT was used in 95% of hospitals, with the highest use being in the emergency department. HNFT was widely used outside of a critical care setting. HFNT was mostly used to treat acute type 1 respiratory failure (98%), followed by acute type 2 respiratory failure and chronic respiratory failure. Guideline development was felt to be important (96%) and urgent (81%). Auditing of practice was lacking in 71% of hospitals. In the USA, HFNT was broadly similar to UK and Canadian practice. (4) Conclusions: The survey results reveal several key points: (a) HFNT is used in clinical conditions with limited evidence; (b) there is a lack of auditing; (c) it is used in wards that may not have the appropriate skill mix; and (d) there is a lack of guidance for HFNT use.
BackgroundAcute Type 2 respiratory failure (AT2RF) is defined by hypercapnia (>6kPa) and these patients require ventilatory support in a significant proportion of cases. Non-invasive ventilation (NIV) is effective in preventing escalation to invasive mechanical ventilation (IMV) but has a high failure rate. High flow nasal oxygen (HFNO) is a novel device that integrates humidified air with oxygen at flow rates of up to 60 L/min. Various additional benefits including carbon-di-oxide (CO2) clearance have been attributed to HFNO. This systematic review aims to determine whether the use of HFNO for patients with AT2RF 1) improves arterial CO2 (PaCO2), 2) improves other clinical and patient-centred outcomes and 3) assess any potential harms.MethodSearches for relevant studies will be conducted in MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials, with no language restrictions. In addition, we will search Google Scholar and the references of all articles for any pertinent studies not found in our initial search. With the assistance of a professional librarian, we will develop a systematic search strategy using appropriate keywords and MeSH terms. We will identify trials that examined the efficacy of HFNO in adult AT2RF patients. We will include randomised trials and observational studies that compared two or more modalities of oxygen delivery that includes high flow nasal oxygen as one of the modes with the comparator being low flow oxygen and/or non-invasive ventilation. The primary outcome is change in PaCO2 level while other clinical and patient centred outcomes will be collected. Two reviewers will independently assess studies for eligibility, data extraction and quality appraisal. We will conduct a meta-analysis and/or a narrative summary as appropriate.DiscussionHFNO is utilised extensively in clinical practice with widening indications of use. The effects of HFNO includes CO2 clearance and PEEP benefits that may be beneficial to patients with AT2RF. While current publications indicate a beneficial role, no systematic review has attempted to summarise the evidence for this indication. The results of the proposed systematic review will summarise the current evidence to guide practice, guideline development and the design of future trials.Systematic review registrationPROSPERO CRD42019148748. (https://www.crd.york.ac.uk/prospero/)
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