263 e-Letters

  • A validation of the National Early Warning Score to predict outcome in patients with COPD exacerbation - Author response

    We thank Cardwell et al for their thoughtful comments on our paper.[1] The two alternative scoring systems did not demonstrate improved discrimination or calibration in our large dataset of AECOPD admissions. The authors suggest employing the Salford-NEWS only in patients ‘at risk’ of hypercapnic respiratory failure however, this introduces a subjective element that may negate the benefits of an objective physiological scoring system. As we emphasised in what we believe was a balanced discussion, patients with COPD should be managed in the right place by specialists and on-going education is crucial to avoid potential harms associated with misinterpretation of the NEWS alluded to by Cardwell and colleagues. Our article adds evidence that suggested RCP thresholds would indeed lead to unnecessary callouts in such patients. However, as we proposed, rather than abandon a scoring system that provides the significant advantages of standardisation and familiarity, it is possible to individualise patient management. For example, lowering observation frequency in a patient who is clinically ‘stable’, not increasing oxygen delivery if the prescribed target saturation is achieved, or taking into account prior/baseline physiology when deciding observation frequency and whether a senior review is required. Indeed a senior review may be appropriate to interpret whether the patient is at risk of hypercapnic respiratory failure and be able to advise on appropriate targets and level of mon...

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  • Extracellular Vesicles Research in Lipopolysaccharide-induced Acute Lung Injury Model

    Dear Editors,
    We are writing to comment on the work entitled “Alveolar macrophage-derived microvesicles mediate acute lung injury” published by Dr. Soni et al on Thorax 2016; 71:1020-1029[1].

    Our group focuses on lung extracellular vesicle (EV) research and also studied the inhaled LPS-induced EVs in mouse models. Based on our experience, we raise the following comments to the work done by Dr. Soni et al and wish to draw attentions to future EV researchers. EV research is a novel field and carries a promising potential for the development of diagnostic and therapeutic agents. However, given the early stage of EV research, particular in the field of lung injury, the consistency of results relies largely on the precise techniques used in the isolation and characterization of these vesicles.

    Briefly, EV is currently classified into three major categories per the definition of Society of extracellular vesicle research [2]. Apoptotic bodies (ABs) are the largest sizes of EVs usually larger than 1 µm and often resulted from cell death. Microvesicles (MVs) are the middle sized EVs (200 nm-1 µm) and are generated via plasma membrane budding. Exosomes (Exos) are the smallest EVs (less than 200 nm) and often generated from IVB-ER-Golgi system. Due to the different mechanisms of generation, MVs and Exos usually favor different compositions and subsequently may carry differential downstream biological functions[3 4]. For example, Exos have been reported to carry t...

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  • NEWS in COPD - Two different uses, one big problem

    I enjoyed reading Hodgson et al’s validation study on Early Warning Scores (EWS) in patients admitted with an exacerbation of COPD. The current problem with EWS such as the National Early Warning Score (NEWS) in such patients is that the score is used in two contexts.

    The first is in the initial triage of patients on arrival to hospital based on their early risk of death. NEWS is well validated in this context, and I wholeheartedly agree that NEWS is the best tool for this at present; patients at risk of type 2 respiratory failure, with target oxygen saturations of 88-92%, are at a high risk of death in hospital and identifying these patients early to enable senior review is entirely appropriate.

    The problem comes with second use of NEWS – as a “track and trigger” tool used to monitor patients during their inpatient stay, with a rising score indicating deterioration, risk of death and the need for intervention. Hodgson et al have confirmed our finding that NEWS lacks specificity for patients with COPD. These patients will often have persistently high NEWS even when stable, well into their admission, and the actions this is supposed to trigger (hourly observations, senior review, etc.) are no longer appropriate. This leads to alarm fatigue, with high scores being ignored, increasing the risk of a true deterioration not being acted upon.

    The proposals of Hodgson et al that such patients should have individually assigned observation frequencie...

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  • Salford NEWS score used incorrectly in paper by Hodgson et al

    We read the paper of Hodgson and colleagues with interest.1 Unfortunately, we note that the Salford-NEWS system (observation chart based on target Oxygen saturation prescription) has been applied in this study to all patients with a diagnosis of acute exacerbation of COPD (AECOPD) whereas we proposed applying this system for all patients at risk of type 2 (hypercapnic) respiratory failure, a group which includes many but not all patients with AECOPD and a number of patients with other conditions.2 Around 86% of those prescribed the lower range of Oxygen saturation (88-92%) in Salford are COPD patients judged to be at risk of hypercapnia, the remainder have conditions such as morbid obesity, neuro-muscular disorders, or complex lung diseases.3 Given this key difference in rationale we suggest that the Salford-NEWS system has been inappropriately applied in this study; hence, the conclusions have to be interpreted with extreme caution.

    When comparing NEWS with Salford-NEWS, it is clear that none of the systems had acceptable sensitivity at score thresholds of 5 and 7, and the most consistently reliable result from using either of them is the negative predictive value, which was similar. It was also evident that Salford-NEWS had better specificity at 91% and 95% compared to 57% and 80% for NEWS at score thresholds of 5 and 7 respectively. Since the increased sensitivity in NEWS is achieved at the expense of high “callout” rates, and low positive predictive value (8%...

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  • Response to: A randomised controlled trial of CPAP vs non-invasive ventilation for initial treatment of obesity hypoventilation syndrome
    Mark E Howard

    Dear Editor, We thank Dr Mansell for her comments regarding our recently published trial. [1] We agree that there are different phenotypic variations within the obesity hypoventilation syndrome (OHS), although it remains to be determined whether OHS with co-existent obstructive sleep apnoea (OSA) responds differently to treatment in comparison to OHS without OSA. [2] Acknowledging that the presence and severity of OSA in...

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  • Comment on: A randomised controlled trial of CPAP versus non-invasive ventilation for initial treatment of obesity hypoventilation syndrome
    Stephanie K. Mansell
    Dear Editor,

    We read with great interest the article by Howard et al[1] and commend the authors on this excellent piece of work. However, we wish to raise several points for consideration of this work in a clinical context. Firstly, it is not clear whether the patients being treated were truly patients with obesity hypoventilation failure (OHS) or whether in fact they had hypercapnic obstructive sleep apnoea (OSA). There is in...

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  • Response to correspondence from Professor Lipworth
    Dale Umetsu

    We thank Professors Lipworth and Anderson for their very thoughtful comments in their response to our piece1, and for pointing out clear strategies for treating obesity-associated asthma without expensive therapies, e.g., with improved delivery of inhaled corticosteroids and/or weight reduction.

    It should be noted however, that the focus of the piece was on mechanisms by which obesity might cause asthma,...

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  • Obesity and asthma - do we need expensive therapies?
    Brian J Lipworth

    We read with interest the state of the art review by Umetsu on mechanisms by which obesity impacts asthma [1]. He has clearly outlined the extent to which molecular targets, both within allergic (T-helper 2 [TH2]) and non-allergic mechanistic pathways of asthma, need further evaluation and drug development for obese asthmatics. This was on the basis that current standard therapies for asthma such as inhaled corticoste...

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  • Authors' Response to: Prediction models for hypersensitivity pneumonitis
    Kerri A. Johannson

    We thank Dr. Lacasse and the HP Study Group for their correspondence regarding 'A diagnostic model for chronic hypersensitivity pneumonitis', and appreciate their thoughtful consideration of our work.(1) We agree that these two studies are complementary, and hope that both will serve to improve diagnostic accuracy in the evaluation of patients with suspected HP. We further concur that much work remains to be done to advan...

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  • Prediction models for hypersensitivity pneumonitis
    Yves Lacasse

    To the Editor,

    The diagnosis of hypersensitivity pneumonitis (HP) is difficult and often relies on an array of clinical symptoms and signs developed in an appropriate setting, with the demonstration of radiographic and tomographic abnormalities, serum precipitating antibodies against offending antigens, a lymphocytic alveolitis on bronchoalveolar lavage, and/or a granulomatous reaction on lung biopsies. Taken...

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