eLetters

290 e-Letters

  • Reply to: Extracorporeal CO2 removal (ECCO2R) in patients with stable COPD with chronic hypercapnia: applying the concept.

    To the Editor

    We thank Dr. Bhakta and colleagues for their interest in our article on the use of extracorporeal CO2 removal (ECCO2R) in patients with stable COPD and chronic hypercapnia (1).
    Bhakta et al. pointed out the role of non invasive ventilation (NIV) to treat chronic hypercapnic respiratory failure by improving alveolar ventilation. The Authors additionally argued that, in evaluating the efficacy of ECCO2R in hypercapnic COPD stable patients who have failed NIV therapy, we only concentrated on the hypercapnic rather than the hypoxic aspects, pointing out that in this population symptomatic relief and long-term CO2 reduction cannot occur without improved oxygenation.
    These points of discussion give us the opportunity to better explain the ECCO2R functioning and consequently the methodology of our study.
    ECCO2R refers to an extracorporeal circuit that is able to selectively extract carbon dioxide from blood with little to no effect on oxygenation. Various ECCO2R systems are now available. In addition to PaCO2 baseline level, the ability of different ECCO2R devices to eliminate CO2 is dependent upon two important determinants: 1) the surface area available for gas exchange and 2) the blood flow rate (2). Moreover, the partial pressure gradient of the gas across the membrane can be obtained by using oxygen or air as sweep gas, according to Fick’s law of diffusion. Because in minimally invasive veno-venous ECCO 2 R systems the ratio of catheter...

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  • Is the use of the Herder score valid in these guidelines?

    Dear Editors,
    This journal published the BTS guidelines for the management of pulmonary nodules in August 2015 (1), leading to widespread evidence-based management of this common clinical problem. The use of the Herder score (2) to estimate or predict the likelihood of malignancy has since become routine in lung cancer MDMs around the country.
    We therefore wish to highlight that the Herder prediction model was developed using the intensity of FDG uptake (absent, faint, moderate or intense) from the uncorrected PET images. However, as far as we are aware, lung cancer MDMs routinely assess the intensity of FDG uptake from the corrected images which is not in accordance with the original Herder model.
    The use of uncorrected images in the original Herder study (2) to distinguish between uptake categories potentially alters the perceived evidence base of the recommendations in the BTS guidelines (1) to distinguish between faint and moderate uptake according to mediastinal blood pool given that this scale of uptake was not used in the original score, has not been validated and could mean we are not using the correct category in the risk model.
    Furthermore, when considering the widespread use of the Herder score, it should be appreciated that it was formulated from patients scanned between 1997 and 2001. The Herder paper describes that “emission scans were acquired in a two-dimensional mode … and were reconstructed using ordered subset expectation maximisa...

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  • Congenital pulmonary airway malformations: what's new?

    We have read with interest the article by Taylor et al. concerning "the mechanism of lung development in the etiology of congenital malformations of the pulmonary airways in adults". The authors discussed the etiology of congenital malformations of the pulmonary airways, suggesting a partial modification of lung development with a potential risk of malignancy.

    Although we generally agree with their assessment, there are some weaknesses in their work that we would like to highlight as well as some points on which we would like to propose an alternative point of view. Different transcription factors known to be involved in lung development have already been studied in CPAM. Two of them, SOX2 and SOX9 are described as important in the spatiotemporal branching development since the pseudoglandular stage [1, 2]. In CPAM, SOX2 is present in both CPAM types (1 and 2), but their expression differs between them [3]. In addition, previously published papers have shown persistent SOX2 expression in healthy lung, which is not the case in this paper. Unfortunately, Talyor et al present "adult" samples and not adjacent healthy. However, this is not sufficient to explain these differences and classical tissues from children should have been included to demonstrate this point. Moreover, a difference in the cells forming the two types of CPAM has already been described by immunohistochemistry and proteomic results. Nevertheless these points are not addressed in t...

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  • Extracorporeal CO2 removal (ECCO2R) in patients with stable COPD with chronic hypercapnia: applying the concept.

    Title: Extracorporeal CO2 removal (ECCO2R) in patients with stable COPD with chronic hypercapnia: applying the concept.
    Pradipta Bhakta, Antonio M. Esquinas, Brian O’Brien.
    Authors:
    1. Dr. Pradipta Bhakta (MD, MNAMS, FCAI, EDRA, EDIC)
    Consultant,
    Department of Anaesthesia and Intensive Care,
    University Hospital Kerry, Tralee, Kerry, Ireland.
    Phone: 00353894137596.
    Email: bhaktadr@hotmail.com
    2. Dr. Antonio M. Esquinas (PhD, MD)
    Consultant,
    Department of Intensive Care,
    Hospital Morales Meseguer,
    Murcia, Spain.
    Phone: 0034609321966
    Email: antmesquinas@gmail.com
    3. Dr. Brian O’Brien [FCARCSI, FJFICMI, FCICM (ANZ)]
    Consultant and Chair,
    Department of Anaesthesia and Intensive Care,
    Cork University Hospital, Cork, Ireland.
    Mobile: 00353877931656
    Email: drbobrien@hotmail.com
    Authors and their role:
    1. Dr. Pradipta Bhakta: Was involved analysis of the article, writing and editing the letter.
    2. Dr. Antonio M. Esquinas: Was involved analysis of the article, writing and editing the letter.
    3. Dr. Brian O’Brien: Was involved analysis of the article, writing and editing the letter.
    Corresponding Author: Dr. Pradipta Bhakta,
    Consultant,
    Departm...

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  • Sneeze is unrealistic

    The sneeze is depicted as horizontal, presumably for the camera. In a real sneeze, the head first tends to first tilt back, but during the actual sneeze, tends to point downwards. This means that large droplets tend to move toward the floor. Would have been nice to see a P2/N95 mask. Apart from that, a useful paper.

  • When to test for alpha-1 antitryspin deficiency in patients with bronchiectasis

    Caretto et al’s brief communication[1] shines some additional light on an unresolved question of the role of alpha-1 antitrypsin deficiency (AATD) screening in patients with bronchiectasis. The authors conclude that testing of an unselected UK population (presumably with a primary diagnosis of bronchiectasis) identifies severe AATD in less than 1% of cases and that routine screening does not significantly impact on clinical management. Whilst these conclusions may be broadly applicable, it may be advisable to qualify the recommendation with some further detail to avoid potential misinterpretation and the consequent complete avoidance of AATD testing in patients with bronchiectasis.

    The study rationale originates from apparent conflicting recommendations of guidelines for bronchiectasis[2] and those for AATD[3]. It is stated by the authors that the latter advises AATD testing in all cases of bronchiectasis, whereas the guidelines (in recommendation 1c) in fact advocate testing in cases of ‘unexplained’ bronchiectasis. The use of the term ‘unexplained’ implies the use of a staged approach to the investigation of bronchiectasis with AATD testing reserved for a selected bronchiectasis population in which a diagnosis remains elusive despite clinically appropriate initial investigations.

    Studies of bronchiectasis in AATD are few in number and relatively small in size. Nevertheless, there is some consistency in the findings. In their conclusions from a study of t...

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  • Awake Prone Positioning in COVID-19 pneumonia: A useful strategy in patients not suitable for mechanical ventilation

    We read with interest the article by Koeckerling et al. (1) regarding ‘Awake Prone
    Positioning in COVID’. The authors have discussed the pros and cons of an
    intervention that is being widely used during the COVID-19 pandemic. Although
    we broadly agree with their assessment, there are some inaccuracies we would
    like to point out as well as a few issues where we would like to offer an
    alternative viewpoint:
    1. Koeckerling and colleagues (1) quote that 78% of patients with severe
    ARDS from a study by Ding et al (2) needed intubation. The original study
    was performed prior to COVID-19 pandemic and reported that 55% of
    patients with moderate to severe ARDS undergoing awake prone
    positioning in conjunction with high flow nasal oxygen (HFNO) /non-
    invasive ventilation (NIV) avoided intubation. All clinicians would agree that
    invasive mechanical ventilation should not be delayed in the face of a
    failing non-invasive intervention. The monitoring of the response to any
    treatment is key to determining the appropriate management plan.
    2. Koeckerling and colleagues report that CT scanning is essential to identify
    which patients would benefit from awake prone positioning but this may not
    be possible in view of the large numbers of patients. Gattinoni et al. do
    describe different phenotypes based on CT appearances, but this is to
    explain the pathophysiology of in different ph...

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  • Covid-19: in the footsteps of Ernest Shackleton. Asymptomatic passengers and crew

    Thank you for inviting us to respond to correspondence from Dr. Andrea Vila, entitled “Active searching for pseudo-asymptomatic contacts during outbreak, as containment measure”.

    We would like to establish in greater details what we defined as “asymptomatic” on board our cruise ship. For the first 8 days, prior to the development of fever in the first subject, our 2 ship’s physicians regularly checked for fever in all passengers in a common area, and attended to calls which were predominantly for sea sickness. After day 8, all passengers and crew were seen by one of the two ship’s physicians twice daily, and had body temperature checks. During these visits, symptoms were enquired about. This includes fever, sore throat, cough and myalgias. In mid-March, anosmia was a recognised symptom of Covid-19 infection and was thus included, but dysgeusia and ageusia were not, and thus Vila makes a valid point. However, given that all passengers and crew were seen twice daily between day 8 and day 28, we are confident in the accuracy of the data presented (81% of Covid-19 subjects being asymptomatic), with the above rider. We do not feel that language was a barrier in communication, with the overwhelming number of passengers and crew either having English as their native language, or being fluent in English. In addition one of the ship’s physicians was multilingual.

    Vila also accurately states that asymptomatic subjects may be pre-symptomatic. We have follow-up on all p...

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  • Active searching for ¨pseudo-asymptomatic¨ contacts during outbreak, as containment measure.

    Dear Editor,
    Ing and colleagues reported a cruise outbreak in which a high prevalence of asymptomatic SARS-coV-2 infection was noticed. Viral shedding can occur in the absence of symptoms and before symptom onset, and asymptomatic patients represent an epidemiological problem of great public health significance. However, it’s noteworthy that the huge number of asymptomatic patients (81%), contrasts with a high percentage of severe illness (9.4%) reported on the population of the cruise ship. So, there seems to be a gap between asymptomatic and severe cases of COVID-19, with just 9.6% of mild and moderate clinically disease.
    Cluster studies conducted in Singapore attributed 6.4% to asymptomatic transmission 1.
    Possibly great part of the population of asymptomatic cases, could have been symptomatic but not meeting the ¨case definition¨ at that time, or pre-symptomatic cases (probably the patients had no evaluation after arrival).
    Initial case definition has been periodically updated as more knowledge about COVID-19 was available 2, adding mild or atypical symptoms such as diarrhea, constitutional symptoms, sudden onset of anosmia, ageusia or dysgeusia. The latter were recognized in late March and published in April, thus scarcely known at the time of the report 3-5. As of June, it has been reported that up to 83% patients with mild illness develop anosmia (without nasal obstruction) or dysgeusia as an early or initial manifestation in the absence of o...

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  • Asthmatic children are less susceptible to Covid-19?

    Dear Editor,
    I read with interest Editorial by Wang et al. (1) regarding treatment of asthma in Covid-19 pandemic. It has been reported that allergic diseases, asthma, and chronic obstructive pulmonary disease were not risk factors for SARS-CoV-2 infection as shown in an earlier report from China (2). On the other hand, early data from Centre for Disease Control and Prevention (CDC) in the US suggest a higher rate of asthma in patients hospitalized for severe Covid-19 illness (3). On this background, patients with severe and uncontrolled asthma have also been included to be at increased risk of developing more severe Covid-19 according to CDC (3). It is however unclear whether increased risk is also relevant to the paediatric age group.
    I agree with the authors that asthma control on a population scale may have improved due to reduced pollution, the use of face masks, better medication adherence and reduced smoking. However, these factors are of lesser importance in the paediatric age group. There is variability in the use of facial masks in different countries. It is most probably that lesser severe illness of Covid-19 in children due to the disease (asthma and respiratory allergy) itself that is offering some kind of protection. That protection seems to more than that being offered by adherence to medical treatment alone. Results from a recent cohort study indicate that children with asthma and allergies have reduced angiotensin-converting enzyme-2 (ACE2) gen...

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