We are grateful to Dr Wilkinson and Professor Woodcock for their comments on our paper.
A key topic raised is related to the assumptions on the timelines to transition to low-Global Warming Potential (GWP) propellants. As of today, several Companies have committed to substantial investments in metered dose inhalers (MDIs) with novel propellants (1-4), indicating developments are progressing fast to target market introduction over the next few years, with 2025 as suggested initial date, and roll-out across portfolios and geographies. Previous transition from CFC to HFC-containing MDIs represents a precedent experience that can be leveraged to ensure a faster process, also dictated by pressure imposed by evolving regulations of HFC use. The new lower global warming potential propellant used for the inhaler transition in this analysis, HFA-152a, has been under development by Koura for an extended period for use in MDIs for the treatment of respiratory disorders such as asthma and COPD (5). In 2020, Koura reported that the US FDA had approved clinical trials with HFA-152a (6) and that the medical-grade propellant has been subject to an extensive suite of inhalation safety testing (including a chronic two-year pre-clinical study). It is understood that this extensive program will be used to support the future commercial use of medical-grade HFA-152a, with the essential Drug Master File expected to be finalized in 2022 (7). We agree that, in addition, the necessary clinic...
We are grateful to Dr Wilkinson and Professor Woodcock for their comments on our paper.
A key topic raised is related to the assumptions on the timelines to transition to low-Global Warming Potential (GWP) propellants. As of today, several Companies have committed to substantial investments in metered dose inhalers (MDIs) with novel propellants (1-4), indicating developments are progressing fast to target market introduction over the next few years, with 2025 as suggested initial date, and roll-out across portfolios and geographies. Previous transition from CFC to HFC-containing MDIs represents a precedent experience that can be leveraged to ensure a faster process, also dictated by pressure imposed by evolving regulations of HFC use. The new lower global warming potential propellant used for the inhaler transition in this analysis, HFA-152a, has been under development by Koura for an extended period for use in MDIs for the treatment of respiratory disorders such as asthma and COPD (5). In 2020, Koura reported that the US FDA had approved clinical trials with HFA-152a (6) and that the medical-grade propellant has been subject to an extensive suite of inhalation safety testing (including a chronic two-year pre-clinical study). It is understood that this extensive program will be used to support the future commercial use of medical-grade HFA-152a, with the essential Drug Master File expected to be finalized in 2022 (7). We agree that, in addition, the necessary clinical evaluation, including appropriate safety and tolerability studies, are required. To that end, active and constructive dialogue has been ongoing for several years with international regulatory agencies, including in both Europe and the US, which have been convened both by those specific pharmaceutical companies committed to lower-GWP inhaler platforms, as well as by across-industry associations. Moreover, under the framework of that agency guidance on the scope and details of the required pre-registration clinical evidence, clinical programs are now underway led by a number of companies in collaboration with external clinical sites. Inevitably these lower-GWP programs are focused on the specific products for which specific companies have the access and rights to transition.
We would also like to point out that our study was intended as a model applied to five different European Countries, with data retrieved collectively from all the Countries involved, and was not focused on the UK. From a clinical perspective, the ultimate goal of performing these analyses is to highlight the possibility of reducing the climate impact of inhalers while maintaining access to the whole range of device options (including both DPIs and pMDIs) to allow optimal treatment personalization, very much in line with the UK approach which is clearly presented by Dr Wilkinson and Professor Woodcock.
We fully agree with the need to reduce carbon footprint by all possible means. Therefore, we deliberately tested different scenarios, including three different rates of switching from DPIs to pMDIs: one is the prolongation of the current trend and two have been called “forced” since they are based on an imposed deadline, which would fit with the definition of a forced strategy. We would of course not question a “clinical” switch based on the goals, outcomes and preferences of care-givers and patients. Modulating preferences through transparent and balanced scientific information is clearly also essential. Part of our paper includes a note regarding the potential risk to disease control that could occur should switching of inhalers be accelerated non-optimally (8). This has been included to encourage a wider approach whereby both benefits and risks of an inhaler change are considered; a holistic approach to patient management when targeting any intervention or change on environmental grounds.
As mentioned above, fighting impactful carbon footprints is absolutely needed and all efforts have to be applauded. It remains true that the contribution of MDIs to global greenhouse-gases (GHG) emissions is low: this suggests that efforts to decrease it should take the time required to do so robustly and safely without risking unwanted clinical consequences for patients; such consequences could happen if treatment options of value for some patients were made unavailable.
We agree that while development progresses, all efforts shall be made to minimize GHG emissions related with treatment of diseases of asthma and COPD. We agree that MART can help improving asthma control in some patients, although it may not be a universal solution: here again, personalization is key. We also agree that MART can be implemented with both DPIs and pMDIs, and this should be supported to allow appropriate personalization of device choice. Moreover, a multi-stakeholder approach including all contributors to the patient and inhaler journey should be encouraged, going beyond simply addressing the environmental impact of inhalers and concentrating on the wider challenge of reducing the carbon footprint of the sub-optimally controlled respiratory patient (9). Focusing solely on inhaler carbon footprint would truly represent a missed opportunity to improve respiratory disease management while simultaneously reducing the environmental impact.
Comments are made regarding the carbon footprint values which have been cited. Our model was built utilizing lifecycle analyses of carbon footprint data available (10-12) at the time of publication and in alternative estimates published elsewhere (13), matching the average values proposed. We welcome other sources of carbon footprint values based on recognized standards, in order to continue to develop in the future more accurate calculations, rather than relying on estimated values.
Regarding the point of the possible influence of conflicts of interest on the content of our paper. Some authors are indeed employed by Chiesi or by companies engaged by Chiesi to perform the analysis as experts in the field. Conversely, NR is an independent academic clinician and clinical researcher with fully transparent, balanced and exhaustively disclosed links of interest with many companies involved in the development of inhaled therapy for asthma and COPD deploying pMDIs, DPIs and SMIs. He contributed critically to the analysis plan, especially to the design of tested scenarios and data interpretation. As well, CS is a primary care based respiratory nurse, not an employee for Chiesi and who did not receive any payment for this work.
We are strongly supportive of efforts to reduce the carbon footprint of inhalers. We believe this should be achieved by providing easily understood information to patients and health care workers to be able to make informed decisions about their inhaled treatments. Near term changes prioritising controller medication with the very large range of available Dry powder inhalers (DPIs) could reduce the carbon footprint by 90%, bringing the UK in line with the rest of Europe.
The paper is essentially written by Chiesi pharmaceuticals. We are concerned about potential bias in the paper arising from this conflict of interest. Chiesi are to be applauded for having committed substantial R&D to the development of metered dose inhalers (MDIs) containing a novel lower GWP propellant HFC-152a to replace high GWP 134a. They are one of only two companies who have announced a transition using HFC-152a for their large range of MDIs.(1,2) However, the paper contains a number of inaccuracies, and is over-optimistic on the timing and pace of transition.
The timelines for achieving a transition to HFC 152a pMDIs are unrealistic; the transition to HFA152a is likely to take far longer than described in the paper. So far, no safety or efficacy data is available for any inhaler containing HFC-152. No detail on requirements for HFC 152a inhalers has been published by the regulatory agencies, although it seems almost certain that long-term human safety data will be required.(3)...
We are strongly supportive of efforts to reduce the carbon footprint of inhalers. We believe this should be achieved by providing easily understood information to patients and health care workers to be able to make informed decisions about their inhaled treatments. Near term changes prioritising controller medication with the very large range of available Dry powder inhalers (DPIs) could reduce the carbon footprint by 90%, bringing the UK in line with the rest of Europe.
The paper is essentially written by Chiesi pharmaceuticals. We are concerned about potential bias in the paper arising from this conflict of interest. Chiesi are to be applauded for having committed substantial R&D to the development of metered dose inhalers (MDIs) containing a novel lower GWP propellant HFC-152a to replace high GWP 134a. They are one of only two companies who have announced a transition using HFC-152a for their large range of MDIs.(1,2) However, the paper contains a number of inaccuracies, and is over-optimistic on the timing and pace of transition.
The timelines for achieving a transition to HFC 152a pMDIs are unrealistic; the transition to HFA152a is likely to take far longer than described in the paper. So far, no safety or efficacy data is available for any inhaler containing HFC-152. No detail on requirements for HFC 152a inhalers has been published by the regulatory agencies, although it seems almost certain that long-term human safety data will be required.(3)
This makes a projected start date of 2025 extremely challenging for any HFC 152a pMDI. The best modelled scenario in the paper assumes an HFC 152a product will be available for every single pMDI product on the market within a 6 month period starting in 2025, and for the transition would be completed within just 2 years. The switch from CFC to HFC-containing MDIs took 20 years, and this 2-year transition period seems totally unrealistic. Other companies will also need time to reformulate, obtain regulatory approval, and launch ranges of MDIs around the world.
Continued pMDI use is compared with “forced switching” to DPIs/SMIs. This is a false premise - nobody is encouraging a “forced” switch or the removal of pMDIs as an option. This unfairly implies that efforts to cut the carbon footprint of therapy involve forcing patients onto inhaler devices they don’t want. On the contrary, in the UK the enforced switch has been in the opposite direction, and solely based on cost. In 2000, two-thirds of inhaled steroid inhalers were DPIs, but this has reduced to 9%, despite evidence that asthma control deteriorated and that multi-dose DPIs appear to be the devices most favoured by patients.(4)
NHS incentives only promote the use of DPIs where it is clinically appropriate, and they exist alongside incentives to improve care by cutting over-reliance on reliever inhalers and promoting adherence to maintenance therapy.(5) The NICE decision aid aims to inform patients about all aspects of inhaler use including their carbon footprint of therapy so they can make a fully informed decision.(6) A recent very large survey of asthma patients shows that they want their therapy to have a lower carbon footprint and most are willing to switch inhalers to achieve this.(7) Far from being a “forced switch”, current efforts involve working alongside patients to find the most convenient and preferred inhaler that patients can and will use, prioritising those with the lowest carbon footprint, and most important improving asthma control. Arguments about “forced switching” unhelpfully undermine these efforts.
The quoted carbon footprint figures used for propellant-free DPIs and SMIs inhalers are inaccurate and too high. A figure of 1.25kg is used for most DPIs, though it's unclear how this figure was reached. It was not the figure used in the reference.(8) There have been many life cycle analyses of non-propellant inhalers published recently, with carbon footprint varying from 0.19-0.9kg. For the Breezhaler, 0.75kg is used in the paper, though life-cycle analysis shows it has a carbon footprint of 0.19-0.38kg depending on how many days the device is re-used for.(9) The figures for soft mist inhalers assume these inhalers are never re-filled, even though refills are in common clinical use (in the UK at least) and can reduce the carbon footprint to as little as 0.225kg per 30 days. (10)
The article makes repeated references to the small contribution of pMDIs to global greenhouse gas emissions, implying that efforts to address this are unnecessary (at least until their own lower GWP inhalers are available!). pMDIs account for 13% of NHS carbon footprint related to the delivery of care,(4) and for a company like GSK around 45% - not at all trivial.(11) The climate crisis is such that all areas of society need to urgently do everything possible to minimise greenhouse gas emissions. A small contribution to the greatest threat to public health the world faces is highly valuable. Moreover, patients care about the carbon footprint of their treatment and most want to minimise its impact where possible.(7)
The article underestimates the impact of recycling by assuming only 25% of propellant is left within the inhaler. A previous national inhaler recycling scheme in the UK found far more wasteful use of MDIs in real-world practice, with 48% of doses remaining in MDIs (and higher rates of waste seen in MDIs that lack dose counters) but only 27% of doses remaining in DPIs (which all include dose counters).(12) The impact of incineration on the global warming potential of the propellant is also not clear from the paper. Nevertheless, the wasteful use of pMDIs potentially increases the positive impacts of recycling. This greater efficiency of DPI use in real-world practice is not factored into the overall analysis, potentially further biasing the conclusions in favour of pMDIs.
Asthma control across most European countries remains poor, with frequent over-reliance on reliever pMDIs. We agree that efforts to optimise asthma could significantly reduce greenhouse gas emissions, though reductions in the carbon footprint of care could be accelerated if this were instituted alongside prioritisation of DPIs. Most inhalers licensed for MART are DPIs, as are once-daily long-acting ICS/LABA combination inhalers. Greater use of these strategies could have a bigger impact than is shown in the paper if DPIs are prioritised simultaneously.(4) Similarly the carbon footprint of COPD could be improved by promoting smoking cessation, greater uptake of pulmonary rehabilitation, reducing unnecessary inhaled steroid use, and prioritisation of propellant-free inhalers.
The most problematic aspect of the analysis is the unrealistic assumption that an HFA152a inhaler will be available for every single class of drug therapy from 2025. We disagree with the implication that waiting for this novel propellant (whilst Chiesi maintain market dominance with a high GWP 134a MDI), is the best course of action. Whilst we strongly welcome efforts to cut the carbon footprint of pMDIs, there is no certainty that these propellants will be approved, and a complete transition to newer propellants could take decades. There are great opportunities available immediately to work alongside patients to improve care whilst simultaneously cutting the carbon footprint of therapy.
1. https://www.chiesi.com/en/chiesi-outlines-350-million-investment-and-ann... (accessed 22.1.22)
2. https://www.astrazeneca.com/media-centre/articles/2020/investing-in-a-su... (accessed 22.1.22)
3. Pritchard JN. The Climate is Changing for Metered-Dose Inhalers and Action is Needed. Drug Des Devel Ther. 2020;14:3043-3055. Published 2020 Jul 29. doi:10.2147/DDDT.S262141
4. Wilkinson, A, Woodcock, A. The environmental impact of inhalers for asthma: A green challenge and a golden opportunity. Br J Clin Pharmacol. 2021; 1- 7. doi:10.1111/bcp.15135
5. NHS England. Annex B – Investment and Impact Fund: 2021/22 and 2022/23.
6. https://www.nice.org.uk/guidance/ng80/resources/inhalers-for-asthma-pati...
7. D’Ancona G, Cumella A, Renwick L, Walker S. The sustainability agenda and inhaled therapy: what do patients want? In: ERS International Conference. ; 2021.
8. Wilkinson AJK, Braggins R, Steinbach I, Smith J. Costs of switching to low global warming potential inhalers. An economic and carbon footprint analysis of NHS prescription data in England. BMJ Open. 2019;9(10):e028763. doi:10.1136/bmjopen-2018-028763.
9. Mezzi K. Carbon footprint impact of Breezhaler® dry powder inhaler: a life cycle assessment in the UK. IPCRG conference paper. Aug 2021 https://www.ipcrg.org/12368
10. Hänsel M, Bambach T, Wachtel H. Reduced environmental impact of the reusable Respimat® Soft mist™ inhaler compared with pressurised metered-dose inhalers. Adv Ther 2019;36:2487–92. doi: 10.1007/s12325-019- 01028-y.
11. https://www.gsk.com/en-gb/media/press-releases/gsk-announces-major-renew... (accessed 20.01.22)
12. Wilkinson AJK, Anderson G. Sustainability in Inhaled Drug Delivery. Pharmaceut Med. 2020;34(3):191-199. doi:10.1007/s40290-020-00339-8.
What very few know is that more than a dozen research groups have demonstrated that low density-lipoprotein (LDL) participates in the immune system by adhering to and inactivating almost all kinds of microorganisms and their toxic products.1 For instance, compared with normal rats, hypocholesterolemic rats injected with bacteria have a markedly increased mortality which can be ameliorated by injecting purified human LDL. When covered with LDL, the bacteria accumulate and are phagocytosed by macrophages, which are subsequently converted to foam cells. This fact may explain the finding by Yusufuddin et al.2 that mortality was lower among the patients with pneumonia if their LDL-cholesterol was elevated. The same phenomenon was found in a follow-up study of about 30,000 community-dwelling adults by Guirg et al.: LDL-C was inversely associated with the risk of suffering from one or more sepsis events (Table 1).3
LDL-C quartiles Q1 Q2 Q3 Q4
Number of participants 6984 7088 6915 6896
Sepsis events (%) 451 (6.5) 399 (5.6) 304 (4.4) 261 (3.8)
Table 1. The LDL-C quartiles of those who suffered from one or more sepsis events
according to the study by Guirgis et al.3
That high LDL-C may be protective is also evident from a meta-analysis of 19 studies where the authors had followed more than 68,000 elderly people for several years.4 What they found was that those with the highest LDL-cholesterol lived the longest; non...
What very few know is that more than a dozen research groups have demonstrated that low density-lipoprotein (LDL) participates in the immune system by adhering to and inactivating almost all kinds of microorganisms and their toxic products.1 For instance, compared with normal rats, hypocholesterolemic rats injected with bacteria have a markedly increased mortality which can be ameliorated by injecting purified human LDL. When covered with LDL, the bacteria accumulate and are phagocytosed by macrophages, which are subsequently converted to foam cells. This fact may explain the finding by Yusufuddin et al.2 that mortality was lower among the patients with pneumonia if their LDL-cholesterol was elevated. The same phenomenon was found in a follow-up study of about 30,000 community-dwelling adults by Guirg et al.: LDL-C was inversely associated with the risk of suffering from one or more sepsis events (Table 1).3
LDL-C quartiles Q1 Q2 Q3 Q4
Number of participants 6984 7088 6915 6896
Sepsis events (%) 451 (6.5) 399 (5.6) 304 (4.4) 261 (3.8)
Table 1. The LDL-C quartiles of those who suffered from one or more sepsis events
according to the study by Guirgis et al.3
That high LDL-C may be protective is also evident from a meta-analysis of 19 studies where the authors had followed more than 68,000 elderly people for several years.4 What they found was that those with the highest LDL-cholesterol lived the longest; none of the studies found the opposite. After the publication of our meta-analysis, 19 more follow-up studies have been published and with similar results.5
References
1. Ravnskov U, McCully KS. Vulnerable plaque formation from obstruction of vasa vasorum by homocysteinylated and oxidized lipoprotein aggregates complexed with microbial remnants and LDL autoantibodies. Ann Clin Lab Sci. 2009;39:3–16.
2. Yousufuddin M, Sharma UM, Bhagra S, et al. Hyperlipidaemia and mortality among patients hospitalised with pneumonia: retrospective cohort and propensity score matched study. BMJ Open Resp Res 2021;8:e000757. doi:10.1136/ bmjresp-2020-000757
3. Guirgis FW, Donnelly JP, Dodani S et al. Cholesterol levels and long-term rates of community-acquired sepsis. Crit Care. 2016;20:408
4. Ravnskov U, Diamond DM, Hama R, et al. Lack of an association or an inverse association between low-density-lipoprotein cholesterol and mortality in the elderly: a systematic review. BMJ Open. 2016; 6: e010401.
5. Ravnskov U, de Lorgeril M, Diamond DM et al. The LDL paradox: Higher LDL-cholesterol is associated with greater longevity. A Epidemiol Public Health. 2020;3: 1040-7.
Dear Editors
We read with interest the scoping review by Whitmore and colleagues into the post-insertion and pre-decannulation management of tracheostomies in the Intensive Care Unit.1 This important work highlights the need and opportunity for research in some areas of the complex management of these vulnerable patients. However, the manuscript has some significant limitations particularly; search strategy; timing; omission of patient safety recommendations; and patient focus; which we discuss below.
The search strategy is limited to minor variations in the keywords, “ICU”, “Intensive Care Unit” and “Tracheostomy,” which excludes any article with the US “tracheotomy” in the title and international variations in care locations, such as, “Intensive Therapy Unit”, “Critical Care Unit”, “Weaning Unit”, “High Care” and associated abbreviations. The authors themselves refer to “critical care” literature but have omitted this from their strategy. A PubMed search (www.pubmed.ncbi.nlm.nih.gov, 27/8/20) finds 11,553 results for “tracheotomy,” 15,894 results for “tracheostomy” and 25,243 results for “tracheostomy or tracheotomy”.
Furthermore, whilst the search is necessarily time-limited, there has been a recent surge in tracheostomy literature including relevant publications for managing tracheostomy in the COVID-19 pandemic.2-4 Whilst the results from Whitmore and colleagues are a useful benchmark, we fear that the...
Dear Editors
We read with interest the scoping review by Whitmore and colleagues into the post-insertion and pre-decannulation management of tracheostomies in the Intensive Care Unit.1 This important work highlights the need and opportunity for research in some areas of the complex management of these vulnerable patients. However, the manuscript has some significant limitations particularly; search strategy; timing; omission of patient safety recommendations; and patient focus; which we discuss below.
The search strategy is limited to minor variations in the keywords, “ICU”, “Intensive Care Unit” and “Tracheostomy,” which excludes any article with the US “tracheotomy” in the title and international variations in care locations, such as, “Intensive Therapy Unit”, “Critical Care Unit”, “Weaning Unit”, “High Care” and associated abbreviations. The authors themselves refer to “critical care” literature but have omitted this from their strategy. A PubMed search (www.pubmed.ncbi.nlm.nih.gov, 27/8/20) finds 11,553 results for “tracheotomy,” 15,894 results for “tracheostomy” and 25,243 results for “tracheostomy or tracheotomy”.
Furthermore, whilst the search is necessarily time-limited, there has been a recent surge in tracheostomy literature including relevant publications for managing tracheostomy in the COVID-19 pandemic.2-4 Whilst the results from Whitmore and colleagues are a useful benchmark, we fear that the review has likely missed significant studies and is already out of date.
The review fails to address the importance of patient safety in tracheostomy care. The landmark National Confidential Enquiry into Patient Outcome and Death report found that 23.6% patients suffered complications on critical care.5 We recently reported clinical incidents affecting 27.3% tracheostomy patients in 20 diverse centres often resulting in harm, increased length of stay and contributing to death.6 This suggests that safety remains an important aspect of tracheostomy care and should remain a key priority for research.
The review selected published papers against specific criteria but appear to have omitted patient-focussed publications with a focus on quality improvement. In such a complex multidisciplinary field, implementing, changing or standardising practice can have arguably as much impact as studies that evaluate new strategies.6,7 The involvement of patients and their families or carers is also key and allows researchers and service leads to focus on the elements of care that are most important to patients; typically a focus on the quality of care delivered around communication, eating, drinking and time to discharge.8 Initiatives such as the Global Tracheostomy Collaborative (www.globaltrach.org) promote Patient Champions who should be involved in service planning, evaluation and research.9
The critical role of the multidisciplinary team should also be apparent from any search of recent tracheostomy literature.10 We appreciate the emphasis the authors place on the important role of Speech and Language Therapists in tracheostomy weaning, decannulation and quality of life but feel the role of Fibreoptic Endoscopic Evaluation of Swallow (FEES) is underemphasised.11 This investigation has greater sensitivity than bedside clinical assessment and Evans Blue Dye Test, can be performed safely at the bedside and may detect upper airway abnormalities important in weaning.12 (Respiratory) Physiotherapists play a key role in sputum clearance, ventilator associated pneumonia reduction and promotion of early mobilisation in the mechanically ventilated, tracheostomy patient which leads to increased functional recovery.13
Whilst we agree with Whitmore & Colleagues’ conclusions that the literature is limited when it comes to post-insertion tracheostomy management, there is additional evidence that is relevant and worthy of inclusion in such a scoping review. We would particularly highlight the need for involvement of patients and the multidisciplinary team in future research and to focus on quality improvement programs alongside discovery science in building the evidence base for comprehensively better tracheostomy care in the future.
References:
1. Whitmore KA, Townsend SC, Laupland KB. Management of tracheostomies in the intensive care unit: a scoping review. BMJ Open Respir Res. 2020;7(1):e000651. doi:10.1136/bmjresp-2020-000651
2. McGrath BA, Ashby N, Birchall M, et al. Multidisciplinary guidance for safe tracheostomy care during the COVID-19 pandemic: the NHS National Patient Safety Improvement Programme (NatPatSIP) [published online ahead of print, 2020 May 12]. Anaesthesia. 2020;10.1111/anae.15120. doi:10.1111/anae.15120
3. Zaga CJ, Pandian V, Brodsky MB, et al. Speech-Language Pathology Guidance for Tracheostomy During the COVID-19 Pandemic: An International Multidisciplinary Perspective. Am J Speech Lang Pathol. 2020;29(3):1320-1334. doi:10.1044/2020_AJSLP-20-00089
4. McGrath BA, Brenner MJ, Warrillow SJ, et al. Tracheostomy in the COVID-19 era: global and multidisciplinary guidance. Lancet Respir Med. 2020;8(7):717-725. doi:10.1016/S2213-2600(20)30230-7
5. Wilkinson K, Freeth H, Kelly K. 'On the Right Trach?' A review of the care received by patients who undergo tracheostomy. Br J Hosp Med (Lond). 2015;76(3):163-165. doi:10.12968/hmed.2015.76.3.163
6. McGrath BA, Wallace S, Lynch J, et al. Improving tracheostomy care in the United Kingdom: results of a guided quality improvement programme in 20 diverse hospitals. Br J Anaesth. 2020;125(1):e119-e129. doi:10.1016/j.bja.2020.04.064
7. McGrath BA, Lynch J, Bonvento B, et al. Evaluating the quality improvement impact of the Global Tracheostomy Collaborative in four diverse NHS hospitals. BMJ Qual Improv Rep. 2017;6(1):bmjqir.u220636.w7996. Published 2017 May 23. doi:10.1136/bmjquality.u220636.w7996
8. Ng FK, Liney T, Dawson R, et al. By the Patient, for the Patient. Determining key quality of care measures for improving tracheostomy care. Med Res Arch. 2019;7(11) doi:10.18103/mra.v7i11.1989
9. Brenner MJ, Pandian V, Milliren CE, et al. Global Tracheostomy Collaborative: data-driven improvements in patient safety through multidisciplinary teamwork, standardisation, education, and patient partnership. Br J Anaesth. 2020;125(1):e104-e118. doi:10.1016/j.bja.2020.04.054
10. Bonvento B, Wallace S, Lynch J, Coe B, McGrath BA. Role of the multidisciplinary team in the care of the tracheostomy patient. J Multidiscip Healthc. 2017;10:391-398. Published 2017 Oct 11. doi:10.2147/JMDH.S118419
11. McGrath BA, Wallace S. The UK National Tracheostomy Safety Project and the role of speech and language therapists. Curr Opin Otolaryngol Head Neck Surg. 2014;22(3):181-187. doi:10.1097/MOO.0000000000000046
12. Neumeier AT, Moss M. We need an additional seat at the critical care multidisciplinary team table for our speech-language pathologists. Ann Am Thorac Soc. 2014;11(10):1610-1611. doi:10.1513/AnnalsATS.201411-515ED
13. Schweickert WD, Pohlman MC, Pohlman AS, et al. Early physical and occupational therapy in mechanically ventilated, critically ill patients: a randomised controlled trial. Lancet. 2009;373(9678):1874-1882. doi:10.1016/S0140-6736(09)60658-9
We are grateful that scientists around the world are showing interest in our research, and delighted to reply to comments from Creaney et al. with regards to our paper the “Biological effect of tissue plasminogen activator (t-PA) and DNase intrapleural delivery in pleural infection patients”.[1]
Pleural infection is a significant clinical entity, has increasing incidence worldwide and is associated with high morbidity, mortality and burden to healthcare services. Effective treatment still relies upon effective pleural fluid drainage, and thus investigation of the pathological mechanisms behind fluid formation and treatment response is key to improving care.
The MIST2 study demonstrated that intrapleural delivery of tissue plasminogen activator (t-PA) alone or t-PA plus DNase increased volume of pleural fluid drained in humans with pleural infection, in a placebo controlled double blind randomised study.[2 ] Although the exact biological mechanisms via which t-PA induces the volume increment of drained pleural fluid are unknown, the design of the MIST2 study means that we are confident in the biological observation of increased fluid production in response to t-PA administration. Lansley et al. have demonstrated that the chemokine MCP-1 (also known as CCL-2) is the key protein that upon intrapleural t-PA administration induces fluid formation in healthy mice.[3]
We designed a study to directly assess their hypothesis in human pleural infection patients fo...
We are grateful that scientists around the world are showing interest in our research, and delighted to reply to comments from Creaney et al. with regards to our paper the “Biological effect of tissue plasminogen activator (t-PA) and DNase intrapleural delivery in pleural infection patients”.[1]
Pleural infection is a significant clinical entity, has increasing incidence worldwide and is associated with high morbidity, mortality and burden to healthcare services. Effective treatment still relies upon effective pleural fluid drainage, and thus investigation of the pathological mechanisms behind fluid formation and treatment response is key to improving care.
The MIST2 study demonstrated that intrapleural delivery of tissue plasminogen activator (t-PA) alone or t-PA plus DNase increased volume of pleural fluid drained in humans with pleural infection, in a placebo controlled double blind randomised study.[2 ] Although the exact biological mechanisms via which t-PA induces the volume increment of drained pleural fluid are unknown, the design of the MIST2 study means that we are confident in the biological observation of increased fluid production in response to t-PA administration. Lansley et al. have demonstrated that the chemokine MCP-1 (also known as CCL-2) is the key protein that upon intrapleural t-PA administration induces fluid formation in healthy mice.[3]
We designed a study to directly assess their hypothesis in human pleural infection patients following intrapleural delivery of t-PA, using pleural fluid specimens collected for MIST2.
Our data suggest that MCP-1 is not the single modulator of the increment in pleural fluid drainage volume due to intrapleural administration of t-PA in humans. Furthermore, no correlation was detected between pleural fluid MCP-1 protein concentration and the volume of drained pleural fluid or the intrapleural drug given.
These data highlight the importance of the appropriate use of laboratory models when extrapolating preclinical findings to human biology.[4-6] Lansley et al. used a single mouse strain of the same sex for experiments (female CD1), and gave a single dose of drug to mice, while MIST2 participants received daily cumulative doses. It is unclear how the dose was adjusted to mouse body surface area. The mice were healthy, and the pleural cavity was not infected with bacteria in contrast to MIST2 samples which were derived from confirmed cased of pleural infection – it is well recognised that the presence of bacteria in the pleural space drastically affects the biological microenvironment.[7, 8]
These factors could explain the differences between our and their studies. Importantly, we highlight that our data suggest that MCP-1 plays a role but is not acting in isolation. More research is needed in order to fully understand the interplay between the pleura, bacteria and t-PA – however, the suggestion that MCP-1 is the sole driver of fluid formation in the human response to intrapleural t-PA based on a healthy mouse model is overly simplistic.
With regards to methodological comments from Creaney et al. we can clarify that total protein concentration was used in order to normalise the concentration of MCP-1. We did not use the total MCP-1 expression as suggested as this would not have allowed us to investigate the correlation between volume of pleural fluid drained and concentration of MCP-1 in pleural fluid. Their suggestion that adjusting for the total volume of pleural fluid present is required is not in our view rational, and makes the assumption that the concentration of MCP-1 is somehow different in the retained fluid in the thorax than that collected, and we see no justification for this assumption. The major pleural fluid parameters used in daily clinical practice (total protein, glucose, LDH) are all measured using concentrations – do they suggest that these parameters are not reliable unless the entire pleural space is drained, or unless total amount is measured? We are also somewhat surprised at their suggestion of the primacy of total (as opposed to concentration) of MCP-1, given that many papers routinely report the concentration of cytokines in pleural fluid (and not total amount) including papers published by the authors of the e-letter to which we here respond, including in their own studies of MCP-1.[9-13] Their suggestion that DNase may have interfered with the analysis is not based on any published data we can find - DNase is an enzyme that cleaves the phosphodiester linkages in DNA molecules and no interaction with chemokines has been reported. We acknowledge that the residual pleural fluid is a limitation of the study. However, even in animal models there is loss of fluid during aspiration.
There is no doubt that laboratory animal models of human disease are of importance and have significantly contributed to major scientific discoveries. However, preclinical disease models must be used with care to ensure that they faithfully and appropriately reflect the properties of any studied disease, and their purposes (which is to study the human disease condition) should not be forgotten. Creaney et al. conclude by suggesting that “Clinical observations are useful in generating hypotheses”. The MIST2 study was not a “clinical observation” and remains the only placebo controlled double blind study in humans with pleural infection treated with t-PA and DNase, and as such, translational discoveries from this dataset are likely to most closely represent the underlying pathobiology in human pleural infection.
References
1. Kanellakis NI, Wrightson JM, Hallifax R, et al. Biological effect of tissue plasminogen activator (t-PA) and DNase intrapleural delivery in pleural infection patients. BMJ Open Respir Res 2019;6(1):e000440. doi: 10.1136/bmjresp-2019-000440 [published Online First: 2019/11/02]
2. Rahman NM, Maskell NA, West A, et al. Intrapleural use of tissue plasminogen activator and DNase in pleural infection. N Engl J Med 2011;365(6):518-26. doi: 10.1056/NEJMoa1012740 [published Online First: 2011/08/13]
3. Lansley SM, Cheah HM, Varano Della Vergiliana JF, et al. Tissue plasminogen activator potently stimulates pleural effusion via a monocyte chemotactic protein-1-dependent mechanism. Am J Respir Cell Mol Biol 2015;53(1):105-12. doi: 10.1165/rcmb.2014-0017OC [published Online First: 2014/12/05]
4. Hackam DG, Redelmeier DA. Translation of research evidence from animals to humans. JAMA 2006;296(14):1731-2. doi: 10.1001/jama.296.14.1731 [published Online First: 2006/10/13]
5. Knight A. Systematic reviews of animal experiments demonstrate poor contributions toward human healthcare. Rev Recent Clin Trials 2008;3(2):89-96. doi: 10.2174/157488708784223844 [published Online First: 2008/05/14]
6. Roberts I, Kwan I, Evans P, et al. Does animal experimentation inform human healthcare? Observations from a systematic review of international animal experiments on fluid resuscitation. BMJ 2002;324(7335):474-6. doi: 10.1136/bmj.324.7335.474 [published Online First: 2002/02/23]
7. Corcoran JP, Wrightson JM, Belcher E, et al. Pleural infection: past, present, and future directions. Lancet Respir Med 2015;3(7):563-77. doi: 10.1016/S2213-2600(15)00185-X [published Online First: 2015/07/15]
8. Lee YC, Idell S, Stathopoulos GT. Translational Research in Pleural Infection and Beyond. Chest 2016;150(6):1361-70. doi: 10.1016/j.chest.2016.07.030 [published Online First: 2016/08/16]
9. Thomas R, Cheah HM, Creaney J, et al. Longitudinal Measurement of Pleural Fluid Biochemistry and Cytokines in Malignant Pleural Effusions. Chest 2016;149(6):1494-500. doi: 10.1016/j.chest.2016.01.001 [published Online First: 2016/02/03]
10. Bielsa S, Davies HE, Davies RJ, et al. Reproducibility and reliability of pleural fluid cytokine measurements. Eur Respir J 2009;34(4):1001-3. doi: 10.1183/09031936.00088409 [published Online First: 2009/10/03]
11. Jin HY, Lee KS, Jin SM, et al. Vascular endothelial growth factor correlates with matrix metalloproteinase-9 in the pleural effusion. Respir Med 2004;98(2):115-22. doi: 10.1016/j.rmed.2003.09.002 [published Online First: 2004/02/20]
12. Rovina N, Dima E, Psallidas I, et al. Interleukin-18 is up-regulated in infectious pleural effusions. Cytokine 2013;63(2):166-71. doi: 10.1016/j.cyto.2013.04.017 [published Online First: 2013/05/11]
13. Lansley SM, Cheah HM, Lee YC. Role of MCP-1 in pleural effusion development in a carrageenan-induced murine model of pleurisy. Respirology 2017;22(4):758-63. doi: 10.1111/resp.12951 [published Online First: 2016/11/24]
Monocyte chemotactic protein (MCP)-1 has raised interests concerning its role in pleural
fluid formation. Recent preclinical studies have found that antagonists against MCP-1
reduces formation of malignant pleural effusions from lung cancer1 and mesothelioma as
well as from benign (carrageenan-induced) pleuritis2 in murine models. In humans,
longitudinal collection of malignant effusions via indwelling pleural catheters also showed a
rise in MCP-1 level over time.3
In humans and animals, pleural instillation of fibrinolytics such as tissue plasminogen
activator (tPA) consistently generates large volume of pleural fluid formation in healthy as
well as in various pleural disease states4, 5. In mice, MCP-1 antagonists also decrease tPA-induced
fluid formation.6
We therefore read with interest the work by Kanellakis et al7 on measuring MCP-1
concentration in pleural fluid samples collected from patients in the MIST (Multicentre
Intrapleural Sepsis Trial)-24 who were given tPA or placebo.
The study by Kanellakis et al7 highlights the challenges and limitations of using clinical
samples/data to decipher biological signals. They reported that following tPA installation,
MCP-1 level in pleural fluid increased. However, the pleural fluid MCP-1 levels were similar,
and not significantly higher, in the tPA-treated patients compared with those who did not
receive tPA.
Monocyte chemotactic protein (MCP)-1 has raised interests concerning its role in pleural
fluid formation. Recent preclinical studies have found that antagonists against MCP-1
reduces formation of malignant pleural effusions from lung cancer1 and mesothelioma as
well as from benign (carrageenan-induced) pleuritis2 in murine models. In humans,
longitudinal collection of malignant effusions via indwelling pleural catheters also showed a
rise in MCP-1 level over time.3
In humans and animals, pleural instillation of fibrinolytics such as tissue plasminogen
activator (tPA) consistently generates large volume of pleural fluid formation in healthy as
well as in various pleural disease states4, 5. In mice, MCP-1 antagonists also decrease tPA-induced
fluid formation.6
We therefore read with interest the work by Kanellakis et al7 on measuring MCP-1
concentration in pleural fluid samples collected from patients in the MIST (Multicentre
Intrapleural Sepsis Trial)-24 who were given tPA or placebo.
The study by Kanellakis et al7 highlights the challenges and limitations of using clinical
samples/data to decipher biological signals. They reported that following tPA installation,
MCP-1 level in pleural fluid increased. However, the pleural fluid MCP-1 levels were similar,
and not significantly higher, in the tPA-treated patients compared with those who did not
receive tPA.
We suggest that this paradox can easily be explained by the way the authors chose to
analyse the data. If the hypothesis is that tPA induces MCP-1 formation within the pleural
cavity which in turn drives fluid formation, it should be the total amount of MCP-1, rather than
its concentration in the fluid after tPA installation, that should be captured. This is critical as
MCP-1 concentration is directly confounded by the amount of fluid generated. The more
potent MCP-1 induces fluid, the lower the pleural fluid MCP-1 concentration will become. It
is important to consider the great differences in the volume drained in the tPA treated groups
(mean 1700 and 1730 mL) compared with non-tPA groups (mean 699 and 725 mL). We
anticipate that the total amount of MCP-1 induced (concentration in fluid multiplied by its
volume) would be significantly higher in the tPA-treated groups. We urge the authors to reanalyse
the data as it is likely to change the conclusion of the paper.
In figure 27, MCP-1 results were presented as 'pg/mg protein'. No information was given on
what protein concentration the MCP-1 level was adjusted to, how protein was measured and
the rationale justifying these choices. It is common in cell culture studies to adjust cytokine
levels to total protein as a partial way to adjust for variations in cell numbers within each well.
However, it is unusual (and probably incorrect) to adjust cytokine levels to pleural fluid
proteins especially given the variations in protein concentration of patients' pleural fluid.
This paper highlights also the importance of vigorously examining confounding factors
before assigning biological meanings to clinical trial samples, especially when the trial was
not designed to test the particular biological concept. In MIST-2, the primary endpoint data
showed that radiographic improvement was only in the range of ~17% (in non-tPA treated
groups) to 30% (in the tPA/DNase group). Residual fluid was thus common and potentially in
significant volumes. The fluid drained may therefore only represent part of the entire pleural
fluid volume. Correlation of the fluid volume drained with cytokine levels is difficult to
interpret and can probably be misleading. Volume drained would also be significantly
affected by chest tube blockage or misplacement, which the authors have shown to affect up
to 42% of patients who had small bore tubes in a malignant effusion trial8. Baseline pleural
fluid and MCP-1 levels also varied among patients. The stability of MCP-1 in the presence of
other proteinases, including DNase, is not known.
Formation of pleural fluid is without a doubt a complex interplay of numerous mediators. We
agree with the authors that MCP-1 is only part of the pathogenic milieu. This was reflected in
all the animal model papers on MCP-1 where its antagonists decrease, but not completely
stop, fluid formation1, 2, 6. Future work will require continual use of information gained from
both laboratory and clinical research. Clinical observations are useful in generating
hypotheses. We must however caution against extrapolating/extending data from clinical
studies, with its many confounders, as a test of disease biology unless the clinical study is
designed, and properly controlled, for evaluating a pathobiological hypothesis.
References
1. Stathopoulos GT, Psallidas I, Moustaki A, et al. A central role for tumor-derived
monocyte chemoattractant protein-1 in malignant pleural effusion. J Natl Cancer Inst.
2008;100(20):1464-76.
2. Lansley SM, Cheah HM, Lee YC. Role of MCP-1 in pleural effusion development in a
carrageenan-induced murine model of pleurisy. Respirology. 2017;22(4):758-63.
3. Thomas R, Cheah HM, Creaney J, Turlach BA, Lee YC. Longitudinal Measurement
of Pleural Fluid Biochemistry and Cytokines in Malignant Pleural Effusions. Chest.
2016;149(6):1494-500.
4. Rahman NM, Maskell NA, West A, et al. Intrapleural use of tissue plasminogen
activator and DNase in pleural infection. N Engl J Med. 2011;365(6):518-26.
5. Thomas R, Piccolo F, Miller D, et al. Intrapleural Fibrinolysis for the Treatment of
Indwelling Pleural Catheter-Related Symptomatic Loculations: A Multicenter Observational
Study. Chest. 2015;148(3):746-51.
6. Lansley SM, Cheah HM, Varano Della Vergiliana JF, Chakera A, Lee YC. Tissue
plasminogen activator potently stimulates pleural effusion via a monocyte chemotactic
protein-1-dependent mechanism. Am J Respir Cell Mol Biol. 2015;53(1):105-12.
7. Kanellakis NI, Wrightson JM, Hallifax R, et al. Biological effect of tissue plasminogen
activator (t-PA) and DNase intrapleural delivery in pleural infection patients. BMJ Open
Respir Res. 2019;6(1):e000440.
8. Rahman NM, Pepperell J, Rehal S, et al. Effect of Opioids vs NSAIDs and Larger vs
Smaller Chest Tube Size on Pain Control and Pleurodesis Efficacy Among Patients With
Malignant Pleural Effusion: The TIME1 Randomized Clinical Trial. Jama.
2015;314(24):2641-53.
We are grateful to Dr Wilkinson and Professor Woodcock for their comments on our paper.
A key topic raised is related to the assumptions on the timelines to transition to low-Global Warming Potential (GWP) propellants. As of today, several Companies have committed to substantial investments in metered dose inhalers (MDIs) with novel propellants (1-4), indicating developments are progressing fast to target market introduction over the next few years, with 2025 as suggested initial date, and roll-out across portfolios and geographies. Previous transition from CFC to HFC-containing MDIs represents a precedent experience that can be leveraged to ensure a faster process, also dictated by pressure imposed by evolving regulations of HFC use. The new lower global warming potential propellant used for the inhaler transition in this analysis, HFA-152a, has been under development by Koura for an extended period for use in MDIs for the treatment of respiratory disorders such as asthma and COPD (5). In 2020, Koura reported that the US FDA had approved clinical trials with HFA-152a (6) and that the medical-grade propellant has been subject to an extensive suite of inhalation safety testing (including a chronic two-year pre-clinical study). It is understood that this extensive program will be used to support the future commercial use of medical-grade HFA-152a, with the essential Drug Master File expected to be finalized in 2022 (7). We agree that, in addition, the necessary clinic...
Show MoreWe are strongly supportive of efforts to reduce the carbon footprint of inhalers. We believe this should be achieved by providing easily understood information to patients and health care workers to be able to make informed decisions about their inhaled treatments. Near term changes prioritising controller medication with the very large range of available Dry powder inhalers (DPIs) could reduce the carbon footprint by 90%, bringing the UK in line with the rest of Europe.
The paper is essentially written by Chiesi pharmaceuticals. We are concerned about potential bias in the paper arising from this conflict of interest. Chiesi are to be applauded for having committed substantial R&D to the development of metered dose inhalers (MDIs) containing a novel lower GWP propellant HFC-152a to replace high GWP 134a. They are one of only two companies who have announced a transition using HFC-152a for their large range of MDIs.(1,2) However, the paper contains a number of inaccuracies, and is over-optimistic on the timing and pace of transition.
The timelines for achieving a transition to HFC 152a pMDIs are unrealistic; the transition to HFA152a is likely to take far longer than described in the paper. So far, no safety or efficacy data is available for any inhaler containing HFC-152. No detail on requirements for HFC 152a inhalers has been published by the regulatory agencies, although it seems almost certain that long-term human safety data will be required.(3)...
Show MoreWhat very few know is that more than a dozen research groups have demonstrated that low density-lipoprotein (LDL) participates in the immune system by adhering to and inactivating almost all kinds of microorganisms and their toxic products.1 For instance, compared with normal rats, hypocholesterolemic rats injected with bacteria have a markedly increased mortality which can be ameliorated by injecting purified human LDL. When covered with LDL, the bacteria accumulate and are phagocytosed by macrophages, which are subsequently converted to foam cells. This fact may explain the finding by Yusufuddin et al.2 that mortality was lower among the patients with pneumonia if their LDL-cholesterol was elevated. The same phenomenon was found in a follow-up study of about 30,000 community-dwelling adults by Guirg et al.: LDL-C was inversely associated with the risk of suffering from one or more sepsis events (Table 1).3
LDL-C quartiles Q1 Q2 Q3 Q4
Number of participants 6984 7088 6915 6896
Sepsis events (%) 451 (6.5) 399 (5.6) 304 (4.4) 261 (3.8)
Table 1. The LDL-C quartiles of those who suffered from one or more sepsis events
according to the study by Guirgis et al.3
That high LDL-C may be protective is also evident from a meta-analysis of 19 studies where the authors had followed more than 68,000 elderly people for several years.4 What they found was that those with the highest LDL-cholesterol lived the longest; non...
Show MoreDear Editors
Show MoreWe read with interest the scoping review by Whitmore and colleagues into the post-insertion and pre-decannulation management of tracheostomies in the Intensive Care Unit.1 This important work highlights the need and opportunity for research in some areas of the complex management of these vulnerable patients. However, the manuscript has some significant limitations particularly; search strategy; timing; omission of patient safety recommendations; and patient focus; which we discuss below.
The search strategy is limited to minor variations in the keywords, “ICU”, “Intensive Care Unit” and “Tracheostomy,” which excludes any article with the US “tracheotomy” in the title and international variations in care locations, such as, “Intensive Therapy Unit”, “Critical Care Unit”, “Weaning Unit”, “High Care” and associated abbreviations. The authors themselves refer to “critical care” literature but have omitted this from their strategy. A PubMed search (www.pubmed.ncbi.nlm.nih.gov, 27/8/20) finds 11,553 results for “tracheotomy,” 15,894 results for “tracheostomy” and 25,243 results for “tracheostomy or tracheotomy”.
Furthermore, whilst the search is necessarily time-limited, there has been a recent surge in tracheostomy literature including relevant publications for managing tracheostomy in the COVID-19 pandemic.2-4 Whilst the results from Whitmore and colleagues are a useful benchmark, we fear that the...
We are grateful that scientists around the world are showing interest in our research, and delighted to reply to comments from Creaney et al. with regards to our paper the “Biological effect of tissue plasminogen activator (t-PA) and DNase intrapleural delivery in pleural infection patients”.[1]
Show MorePleural infection is a significant clinical entity, has increasing incidence worldwide and is associated with high morbidity, mortality and burden to healthcare services. Effective treatment still relies upon effective pleural fluid drainage, and thus investigation of the pathological mechanisms behind fluid formation and treatment response is key to improving care.
The MIST2 study demonstrated that intrapleural delivery of tissue plasminogen activator (t-PA) alone or t-PA plus DNase increased volume of pleural fluid drained in humans with pleural infection, in a placebo controlled double blind randomised study.[2 ] Although the exact biological mechanisms via which t-PA induces the volume increment of drained pleural fluid are unknown, the design of the MIST2 study means that we are confident in the biological observation of increased fluid production in response to t-PA administration. Lansley et al. have demonstrated that the chemokine MCP-1 (also known as CCL-2) is the key protein that upon intrapleural t-PA administration induces fluid formation in healthy mice.[3]
We designed a study to directly assess their hypothesis in human pleural infection patients fo...
Monocyte chemotactic protein (MCP)-1 has raised interests concerning its role in pleural
fluid formation. Recent preclinical studies have found that antagonists against MCP-1
reduces formation of malignant pleural effusions from lung cancer1 and mesothelioma as
well as from benign (carrageenan-induced) pleuritis2 in murine models. In humans,
longitudinal collection of malignant effusions via indwelling pleural catheters also showed a
rise in MCP-1 level over time.3
In humans and animals, pleural instillation of fibrinolytics such as tissue plasminogen
activator (tPA) consistently generates large volume of pleural fluid formation in healthy as
well as in various pleural disease states4, 5. In mice, MCP-1 antagonists also decrease tPA-induced
fluid formation.6
We therefore read with interest the work by Kanellakis et al7 on measuring MCP-1
concentration in pleural fluid samples collected from patients in the MIST (Multicentre
Intrapleural Sepsis Trial)-24 who were given tPA or placebo.
The study by Kanellakis et al7 highlights the challenges and limitations of using clinical
samples/data to decipher biological signals. They reported that following tPA installation,
MCP-1 level in pleural fluid increased. However, the pleural fluid MCP-1 levels were similar,
and not significantly higher, in the tPA-treated patients compared with those who did not
receive tPA.
We sug...
Show More