dead space fraction

BACKGROUND: Ratio of arterial pressure of oxygen and fraction of inspired oxygen (P/F ratio) together with the fractional dead space (Vd /Vt ) provides a global assessment of pulmonary gas exchange. The aim of this study was to assess the potential value of these variables to prognosticate 90-day survival in patients with COVID-19 associated ARDS admitted to the Intensive Care Unit (ICU) for invasive ventilatory support. METHODS: In this single-center observational, retrospective study, P/F ratios and Vd /Vt were assessed up to 4 weeks after ICU-admission...

BACKGROUND: Mortality due to chronic obstructive pulmonary disease (COPD) is increasing. However, dead space fractions at rest (VD /VTrest ) and peak exercise (VD /VTpeak ) and variables affecting survival have not been evaluated. This study aimed to investigate these issues. METHODS: This retrospective observational cohort study was conducted from 2010-2020. Patients with COPD who smoked, met the Global Initiatives for Chronic Lung Diseases (GOLD) criteria, had available demographic, complete lung function test (CLFT), medication, acute exacerbation of COPD (AECOPD), Charlson Comorbidity Index, and survival data were enrolled...

Acute hypoxemic respiratory failure is defined by Pao2 less than 60 mm Hg or SaO2 less than 88% and may result from V/Q mismatch, shunt, hypoventilation, diffusion limitation, or low inspired oxygen tension. Acute hypercapnic respiratory failure is defined by Paco2 ≥ 45 mm Hg and pH less than 7.35 and may result from alveolar hypoventilation, increased fraction of dead space, or increased production of carbon dioxide. Early diagnostic maneuvers, such as measurement of SpO2 and arterial blood gas, can differentiate the type of respiratory failure and guide next steps in evaluation and management...

High-flow nasal cannula (HFNC) has recently emerged as a crucial therapeutic strategy for hypoxemic patients both in acute and chronic settings. Indeed, HFNC therapy is able to deliver higher fractions of inspired oxygen (FiO2 ) with a heated and humidified gas flow ranging from 20 up to 60 L per minute, in a more comfortable way for the patient in comparison with Conventional Oxygen Therapy (COT). In fact, the flow keeps the epithelium of the airways adequately moisturized, thus positively affecting the mucus clearance...

BACKGROUND: Standard high-flow nasal cannula (HFNC) is a respiratory support device widely used to manage post-extubation hypoxemic acute respiratory failure (hARF) due to greater comfort, oxygenation, alveolar recruitment, humidification, and reduction of dead space, as compared to conventional oxygen therapy. On the contrary, the effects of the new asymmetrical HFNC interface (Optiflow® Duet system (Fisher & Paykel, Healthcare, Auckland, New Zealand) is still under discussion...

INTRODUCTION: COVID-19 Related Acute Respiratory Syndrome (C-ARDS) is characterized by a mismatch between respiratory mechanics and hypoxemia, suggesting increased dead-space fraction (DSF). Prone position is a cornerstone treatment of ARDS under invasive mechanical ventilation reducing mortality. We sought to investigate the impact of prone position on DSF in C-ARDS in a cohort of patients receiving invasive mechanical ventilation. METHODS: we retrospectively analysed data from 85 invasively mechanically ventilated patients with C-ARDS in supine and in prone positions, hospitalized in Intensive Care Unit (Reims University Hospital), between November, 1st 2020 and November, 1st 2022...

Geospatial fire behaviour and fire hazard simulators, fire effects models and smoke emission software commonly use standard fuel models in order to simplify data collection and the inclusion of complex fuel scenarios. These fuel models are often mapped using remotely sensed data. However, given the great complexity of fuelbeds, with properties that vary widely in both time and space, the use of these standard fuel models can greatly limit accurate fuel mapping. This affects fuel hazard assessment, fuel reduction treatment plans, fire management decision-making and evaluation of the environmental impact of wildfire...

BACKGROUND: Prone position is used in acute respiratory distress syndrome and in coronavirus disease 2019 (Covid-19) acute respiratory distress syndrome (ARDS). However, physiological mechanisms remain unclear. The aim of this study was to determine whether improved oxygenation was related to pulmonary shunt fraction (Q's/Q't), alveolar dead space (Vd/Vtalv) and ventilation/perfusion mismatch (V'A /Q'). METHODS: This was an international, prospective, observational, multicenter, cohort study, including six intensive care units in Sweden and Poland and 71 mechanically ventilated adult patients...

This article reviewed the clinical progress in the field of pulmonary and critial care medicine, both domestically and internationally during the year 2023 (from October 1, 2022 to September 30, 2023). In 2023, there have been significant modifications to the global definition of Acute Respiratory Distress Syndrome (ARDS). These include the inclusion of SpO2 /FiO2 as a diagnostic criterion for ARDS, the addition of parameters for high-flow nasal cannula humidified oxygen therapy as a basis for diagnosing ARDS in non-intubated patients, clarification of the need to diagnose ARDS in non-intubated patients with PEEP≥5 cmH2 O under non-invasive positive pressure ventilation, and the increased diagnostic value of ultrasound...

Single lung transplantation (LUTX) can be the last therapeutic option for a growing cohort of patients suffering from end-stage respiratory failure. Postoperative ventilatory management of single LUTX recipients is challenged by the coexistence of the diseased native lung and a healthy-but fragile-graft. In this case report, in a single LUTX recipient with idiopathic pulmonary fibrosis, regional ventilation (), perfusion (), and / matching and subsequent measurement of shunt fraction (Qs/Qt) and alveolar dead space (Vd/Vt) were obtained by integrating electrical impedance tomography (EIT) with volumetric capnography and pulmonary thermodilution technique...

Whilst the presence of 2 subphenotypes among the heterogenous Acute Respiratory Distress Syndrome (ARDS) population is becoming clinically accepted, subphenotype-specific treatment efficacy has yet to be prospectively tested. We investigated anti-inflammatory treatment in different ARDS models in sheep, previously shown similarities to human ARDS subphenotypes, in a preclinical, randomized, blinded study. Thirty anesthetized sheep were studied up to 48 h and randomized into: (a) OA: oleic acid (n = 15) and (b) OA-LPS: oleic acid and subsequent lipopolysaccharide (n = 15) to achieve a PaO2 /FiO2 ratio of < 150 mmHg...

PURPOSE: To describe the clinical course of ARDS during the first three days of mechanical ventilation, to compare ventilatory setting, respiratory mechanics and gas exchange variables collected during the first three days of mechanical ventilation between patients who survived and died during intensive care unit (ICU) stay and to investigate the variables associated with mortality at ICU admission and throughout the first three days of mechanical ventilation. MATERIALS AND METHODS: Prospective observational study...

PURPOSE: To evaluate early measurement of the arterial to end-tidal carbon dioxide (PaCO2 -PetCO2 ) gap, a surrogate for physiologic dead space, and its association with clinical outcomes in intubated adults in the emergency department (ED). MATERIALS AND METHODS: Observational cohort study of invasively mechanically ventilated adults in an academic medical center (years 2009 to 2016). The association of the PaCO2 -PetCO2 gap was evaluated with respect to clinical outcomes; the primary outcome was in-hospital mortality...

Despite an increasing number of studies demonstrating the potential mental health benefits of greenspace, few longitudinal studies have been reported. We aimed to assess associations between two metrics of residential greenspace exposure and anxiety symptoms in a cohort of Australian women living in major cities. Our study comprised 3,938 women, born between 1973 and 78. Anxiety symptoms in the previous month were assessed at follow-up every three years during 2003-2018, using the anxiety subscale of the Goldberg Anxiety and Depression Scale...

OBJECTIVE: Accurate and reliable noninvasive methods to estimate gas exchange are necessary to guide clinical decisions to avoid frequent blood samples in children with pediatric acute respiratory distress syndrome (PARDS). We aimed to investigate the correlation and agreement between end-tidal <mml:math xmlns:mml="https://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:mrow><mml:msub><mml:mi>P</mml:mi> <mml:msub><mml:mi>CO</mml:mi> <mml:mn>2</mml:mn></mml:msub> </mml:msub> </mml:mrow> <mml:annotation>${P}_{{\mathrm{CO}}_{2}}$</mml:annotation></mml:semantics> </mml:math> measured immediately after a 3-s inspiratory-hold (PLAT CO2 ) by capnometry and <mml:math xmlns:mml="https://www...

The conditions of temperature, pressure and saturation in which respiratory gas volumes are expressed (STPD, ATPS or BTPS) are physiologically relevant, but often ignored or unknown in clinical practice. In this study we aimed to investigate whether and at which extent the gas volumes corrections, either in natural and artificial lung, may alter key respiratory and metabolic variables and the possible clinical consequences. We primarily referred to the effects of gas volumes corrections on three physiological variables: physiological dead space, venous admixture and total VCO2 during extracorporeal support...

AIMS: It is widely held that heart failure (HF) does not cause exertional hypoxaemia, based upon studies in HF with reduced ejection fraction, but this may not apply to patients with HF and preserved ejection fraction (HFpEF). Here, we characterize the prevalence, pathophysiology, and clinical implications of exertional arterial hypoxaemia in HFpEF. METHODS AND RESULTS: Patients with HFpEF (n = 539) and no coexisting lung disease underwent invasive cardiopulmonary exercise testing with simultaneous blood and expired gas analysis...

(1) Background: The exercise capacity of patients with a left ventricular assist device (LVAD) remains limited despite mechanical support. Higher dead space ventilation (VD /VT ) may be a surrogate for right ventricular to pulmonary artery uncoupling (RV-PA) during cardiopulmonary exercise testing (CPET) to explain persistent exercise limitations. (2) Methods: We investigated 197 patients with heart failure and reduced ejection fraction with ( n = 89) and without (HFrEF, n = 108) LVAD. As a primary outcome NTproBNP, CPET, and echocardiographic variables were analyzed for their potential to discriminate between HFrEF and LVAD...

The aim of this study was to investigate the feasibility of online monitoring of irradiation time (IRT) and scan time for FLASH proton radiotherapy using a pixelated semiconductor detector.&#xD;Approach: Measurements of the time structure of FLASH irradiations were performed using fast, pixelated spectral detectors based on the Timepix3 (TPX3) chips with two architectures: AdvaPIX-TPX3 and Minipix-TPX3. The latter has a fraction of its sensor coated with a material to increase sensitivity to neutrons. With little or no dead time and an ability to resolve events that are closely spaced in time (tens of nanoseconds), both detectors can accurately determine IRTs as long as pulse pile-up is avoided...

RATIONALE: Post-coronavirus disease 2019 (COVID-19) survivors frequently have dyspnoea that can lead to exercise intolerance and lower quality of life. Despite recent advances, the pathophysiological mechanisms of exercise intolerance in the post-COVID-19 patients remain incompletely characterised. The objectives of the present study were to clarify the mechanisms of exercise intolerance in post-COVID-19 survivors after hospitalisation. METHODS: This prospective study evaluated consecutive patients previously hospitalised due to moderate-to-severe/critical COVID-19...