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Open accessJournal ArticleDOI: 10.1016/J.CHEST.2021.02.047

Recommended Approaches to Minimize Aerosol Dispersion of SARS-CoV-2 During Noninvasive Ventilatory Support Can Cause Ventilator Performance Deterioration: A Benchmark Comparative Study.

02 Mar 2021-Chest (Elsevier)-Vol. 160, Iss: 1, pp 175-186
Abstract: BACKGROUND: SARS-CoV-2 aerosolization during noninvasive positive-pressure ventilation may endanger health care professionals. Various circuit setups have been described to reduce virus aerosolization. However, these setups may alter ventilator performance. RESEARCH QUESTION: What are the consequences of the various suggested circuit setups on ventilator efficacy during CPAP and noninvasive ventilation (NIV)? STUDY DESIGN AND METHODS: Eight circuit setups were evaluated on a bench test model that consisted of a three-dimensional printed head and an artificial lung. Setups included a dual-limb circuit with an oronasal mask, a dual-limb circuit with a helmet interface, a single-limb circuit with a passive exhalation valve, three single-limb circuits with custom-made additional leaks, and two single-limb circuits with active exhalation valves. All setups were evaluated during NIV and CPAP. The following variables were recorded: the inspiratory flow preceding triggering of the ventilator, the inspiratory effort required to trigger the ventilator, the triggering delay, the maximal inspiratory pressure delivered by the ventilator, the tidal volume generated to the artificial lung, the total work of breathing, and the pressure-time product needed to trigger the ventilator. RESULTS: With NIV, the type of circuit setup had a significant impact on inspiratory flow preceding triggering of the ventilator (P < .0001), the inspiratory effort required to trigger the ventilator (P < .0001), the triggering delay (P < .0001), the maximal inspiratory pressure (P < .0001), the tidal volume (P = .0008), the work of breathing (P < .0001), and the pressure-time product needed to trigger the ventilator (P < .0001). Similar differences and consequences were seen with CPAP as well as with the addition of bacterial filters. Best performance was achieved with a dual-limb circuit with an oronasal mask. Worst performance was achieved with a dual-limb circuit with a helmet interface. INTERPRETATION: Ventilator performance is significantly impacted by the circuit setup. A dual-limb circuit with oronasal mask should be used preferentially.

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Topics: Tidal volume (51%), Work of breathing (51%)
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Open accessJournal ArticleDOI: 10.1186/S13054-021-03746-8
Andrea Coppadoro, Elisabetta Zago1, Fabio Pavan1, Giuseppe Foti1  +1 moreInstitutions (1)
08 Sep 2021-Critical Care
Abstract: A helmet, comprising a transparent hood and a soft collar, surrounding the patient's head can be used to deliver noninvasive ventilatory support, both as continuous positive airway pressure and noninvasive positive pressure ventilation (NPPV), the latter providing active support for inspiration. In this review, we summarize the technical aspects relevant to this device, particularly how to prevent CO2 rebreathing and improve patient-ventilator synchrony during NPPV. Clinical studies describe the application of helmets in cardiogenic pulmonary oedema, pneumonia, COVID-19, postextubation and immune suppression. A section is dedicated to paediatric use. In summary, helmet therapy can be used safely and effectively to provide NIV during hypoxemic respiratory failure, improving oxygenation and possibly leading to better patient-centred outcomes than other interfaces.

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1 Citations


Journal ArticleDOI: 10.1080/17476348.2021.1997596
Abstract: Introduction : Respiratory high dependency units (RHDU) set up in European countries in the last decade are based on being a transitional step between the intensive care units (ICU) and the conventional hospital ward in terms of staffing, level of monitoring and patients' severity. In the pre-COVID-19 era, its main use has been the treatment of hypercapnic acute-on-chronic respiratory failure with noninvasive respiratory support and more recently for hypoxemic acute respiratory failure. Areas covered We searched the following databases: MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, limited to the terms: COVID-19 AND RHDU, Respiratory Intermediate care Unit, acute respiratory distress syndrome (ARDS), non invasive ventilation (NIV), high flow nasal cannula (HFNC), prone position, monitoring. In this review we summarize RHDU´s dual purpose: on one hand, to decrease the number of admissions into ICU, and on the other hand, early discharges of patients from ICU with prolonged admissions due to the need of care or laborious weaning from invasive mechanical ventilation. Although this dual purpose of RHDUs has contributed to decrease the overload of the ICUs during the pandemic, the hundreds of patients admitted in hospitals, with approximately 20% -30% needing critical care, has exceeded the forecasts of many hospitals. Expert opinion It seems clear that a reorganization and optimization of the care of patients with severe COVID-19 is necessary, minimizing admissions to the ICU and facilitating an early discharge. During the pandemic, several hospitals have spontaneously created new RHDUs or extended pre-existing RHDUs or up-graded respiratory wards in order to receive less sick patients requiring lower levels of monitoring and nurse to patient ratios. This article reviews under a European expert perspective this topic and proposes an adaptation and optimization of the RHDUs to meet the emergent needs caused by the pandemic emphasizing the role of the expert application of noninvasive respiratory therapies in preventing intubation and ICU access.

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Topics: Intensive care (59%), Respiratory failure (56%), Mechanical ventilation (51%) ... show more



Open accessJournal ArticleDOI: 10.1183/23120541.00214-2021
01 Oct 2021-ERJ Open Research
Abstract: During the virtual European Respiratory Society Congress 2020, early career members summarised the sessions organised by the Respiratory Intensive Care Assembly. The topics covered included diagnostic strategies in patients admitted to the intensive care unit with acute respiratory failure, with a focus on patients with interstitial lung disease and for obvious reasons, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. These sessions are summarised in this article, with take-home messages highlighted.

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Topics: Intensive care (64%), Intensive care unit (53%)
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21 results found


Open accessJournal ArticleDOI: 10.1164/RCCM.202003-0817LE
Abstract: ventilation strategy was applied to the first four patients to increase pulmonary efficiency to eliminate CO2, and this was used in the next four patients. Gas exchange consists of oxygenation and ventilation. Oxygenation is quantified by the PaO2/FIO2 ratio, and this method has gained wide acceptance, particularly since publication of the Berlin definition of ARDS (7). However, the Berlin definition does not include additional pathophysiological information about ARDS, such as alveolar ventilation, as measured by pulmonary dead space, which is an important predictor of outcome (8). Increased pulmonary dead space reflects the inefficiency of the lungs to eliminate CO2, which may lead to hypercapnia. In our patients with ARDS with COVID-19, hypercapnia was common at ICU admission with low VT ventilation. Assuming the anatomic portion of dead space is constant, increasing VT with constant respiratory rate would effectively increase alveolar ventilation. Any such increase in VT would decrease PaCO2, which would be captured by VR (6). VR, a novel method to monitor ventilatory adequacy at the bedside (4–6), was very high in our patients, reflecting increased pulmonary dead space and inadequacy of ventilation. With an acceptable plateau pressure and driving pressure, titration of VT was performed. PaCO2 and VR were significantly decreased when an intermediate VT (7–8 ml/kg PBW) was applied. We suggest that intermediate VT (7–8 ml/kg PBW) is recommended for such patients. Therefore, low VT may not be the best approach for all patients with ARDS, particularly those with a less severe decrease in respiratory system compliance and inadequacy of ventilation. In summary, we found that hypercapnia was common in patients with COVID-19–associated ARDS while using low VT ventilation. VR was increased in these patients, which reflected increased pulmonary dead space and inadequacy of ventilation. An intermediate VT was used to correct hypercapnia efficiently, while not excessively increasing driving pressure. Clinicians must have a high index of suspicion for increased pulmonary dead space when patients with COVID19–related ARDS present with hypercapnia. n

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Topics: ARDS (59%)

839 Citations


Journal ArticleDOI: 10.1007/S00134-006-0301-8
Abstract: Objective The incidence, pathophysiology, and consequences of patient-ventilator asynchrony are poorly known. We assessed the incidence of patient-ventilator asynchrony during assisted mechanical ventilation and we identified associated factors.

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665 Citations


Open accessJournal ArticleDOI: 10.1183/13993003.02339-2018
David S.C. Hui1, Benny K. Chow1, Thomas Lo1, Owen Tak-Yin Tsang  +4 moreInstitutions (1)
Abstract: Background High-flow nasal cannula (HFNC) is an emerging therapy for respiratory failure but the extent of exhaled air dispersion during treatment is unknown. We examined exhaled air dispersion during HFNC therapy versus continuous positive airway pressure (CPAP) on a human patient simulator (HPS) in an isolation room with 16 air changes·h−1. Methods The HPS was programmed to represent different severity of lung injury. CPAP was delivered at 5–20 cmH2O via nasal pillows (Respironics Nuance Pro Gel or ResMed Swift FX) or an oronasal mask (ResMed Quattro Air). HFNC, humidified to 37°C, was delivered at 10–60 L·min−1 to the HPS. Exhaled airflow was marked with intrapulmonary smoke for visualisation and revealed by laser light-sheet. Normalised exhaled air concentration was estimated from the light scattered by the smoke particles. Significant exposure was defined when there was ≥20% normalised smoke concentration. Results In the normal lung condition, mean±sd exhaled air dispersion, along the sagittal plane, increased from 186±34 to 264±27 mm and from 207±11 to 332±34 mm when CPAP was increased from 5 to 20 cmH2O via Respironics and ResMed nasal pillows, respectively. Leakage from the oronasal mask was negligible. Mean±sd exhaled air distances increased from 65±15 to 172±33 mm when HFNC was increased from 10 to 60 L·min−1. Air leakage to 620 mm occurred laterally when HFNC and the interface tube became loose. Conclusion Exhaled air dispersion during HFNC and CPAP via different interfaces is limited provided there is good mask interface fitting.

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237 Citations


Open accessJournal ArticleDOI: 10.3310/HTA14460-02
Abstract: Background Influenza viruses are thought to be spread by droplets, but the role of aerosol dissemination is unclear and has not been assessed by previous studies. Oxygen therapy, nebulised medication and ventilatory support are treatments used in clinical practice to treat influenzal infection are thought to generate droplets or aerosols. Objectives Evaluation of the characteristics of droplet/aerosol dispersion around delivery systems during non-invasive ventilation (NIV), oxygen therapy, nebuliser treatment and chest physiotherapy by measuring droplet size, geographical distribution of droplets, decay in droplets over time after the interventions were discontinued. Methods Three groups were studied: (1) normal controls, (2) subjects with coryzal symptoms and (3) adult patients with chronic lung disease who were admitted to hospital with an infective exacerbation. Each group received oxygen therapy, NIV using a vented mask system and a modified circuit with non-vented mask and exhalation filter, and nebulised saline. The patient group had a period of standardised chest physiotherapy treatment. Droplet counts in mean diameter size ranges from 0.3 to > 10 µm were measured with an counter placed adjacent to the face and at a 1-m distance from the subject/patient, at the height of the nose/mouth of an average health-care worker. Results NIV using a vented mask produced droplets in the large size range (> 10 µm) in patients (p = 0.042) and coryzal subjects (p = 0.044) compared with baseline values, but not in normal controls (p = 0.379), but this increase in large droplets was not seen using the NIV circuit modification. Chest physiotherapy produced droplets predominantly of > 10 µm (p = 0.003), which, as with NIV droplet count in the patients, had fallen significantly by 1 m. Oxygen therapy did not increase droplet count in any size range. Nebulised saline delivered droplets in the small- and medium-size aerosol/droplet range, but did not increase large-size droplet count. Conclusions NIV and chest physiotherapy are droplet (not aerosol)-generating procedures, producing droplets of > 10 µm in size. Due to their large mass, most fall out on to local surfaces within 1 m. The only device producing an aerosol was the nebuliser and the output profile is consistent with nebuliser characteristics rather than dissemination of large droplets from patients. These findings suggest that health-care workers providing NIV and chest physiotherapy, working within 1 m of an infected patient should have a higher level of respiratory protection, but that infection control measures designed to limit aerosol spread may have less relevance for these procedures. These results may have infection control implications for other airborne infections, such as severe acute respiratory syndrome and tuberculosis, as well as for pandemic influenza infection.

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Topics: Chest physiotherapy (57%)

191 Citations


Open accessJournal ArticleDOI: 10.1136/THX.2010.142653
01 Jun 2012-Thorax
Abstract: Non-invasive ventilation (NIV) is recognised as an effective treatment for chronic hypercapnic respiratory failure. Monitoring NIV during sleep may be preferable to daytime assessment. This paper reports the findings of an international consensus group which systematically analysed nocturnal polygraphic or polysomnographic tracings recorded with either volume-cycled or pressure-cycled ventilators. A systematic description of nocturnal respiratory events which occur during NIV is proposed: leaks, obstruction at different levels of the upper airway (glottis and/or pharynx), with or without decrease of respiratory drive and asynchrony.

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Topics: Polysomnography (51%)

119 Citations


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