527 research outputs found
Diaphragm Activity and Function During Mechanical Ventilation
No full textPrevious studies suggest that mechanical ventilation (MV) can injure the diaphragm, potentially prolonging ventilator dependence. However, there are many potential insults to diaphragm function during critical illness and the extent to which diaphragm dysfunction is attributable to ventilation remains undefined in the clinical setting. We hypothesized that diaphragm inactivity and/or injurious diaphragm loading during MV mediate diaphragm injury in the clinical setting. To test this hypothesis, we first evaluated the feasibility, validity and reproducibility of novel methods for monitoring the diaphragm in the clinical setting. We found that neuromuscular coupling (NMC), a measure of diaphragm function, is influenced by inspiratory effort, airway flow and diaphragm motion during inspiration and that NMC varies considerably over time in healthy volunteers. We also found that right hemidiaphragm thickness can be measured reproducibly by ultrasound and that increasing diaphragm thickness during inspiration reflects active contractile activity rather than passive chest wall expansion. Subsequently, in a large prospective cohort study (n=107) we demonstrated that diaphragm thickness varies considerably over time in relation to the level of inspiratory effort. Changes in muscle thickness were associated with impaired muscle function. Finally, in a preliminary clinical study (n=10) we confirmed the feasibility of selectively enrolling patients at high risk of prolonged MV and of measuring diaphragm activity and patient-ventilator dyssynchrony on an hourly basis commencing shortly after intubation. We conclude that ultrasound is a useful clinical tool to monitor the diaphragm during MV; NMC measurement requires further standardization and validation. MV likely causes significant diaphragm injury in patients and titrating ventilatory support to maintain normal levels of inspiratory effort may protect the diaphragm from injury during MV. A detailed description of patient exposure to diaphragm inactivity and injurious loading during MV is feasible; such observations could inform the design of muscle-protective ventilation strategies.Ph.D
The End of Chimerica
No full textFor the better part of the past decade, the world economy has been dominated by a world economic order that combined Chinese export-led development with US over-consumption. The financial crisis of 2007-2009 likely marks the beginning of the end of the Chimerican relationship. In this paper we look at this era as economic historians, trying to set events in a longer-term perspective. In some ways China's economic model in the decade 1998-2007 was similar to the one adopted by West Germany and Japan after World War II. Trade surpluses with the U.S. played a major role in propelling growth. But there were two key differences. First, the scale of Chinese currency intervention was without precedent, as were the resulting distortions of the world economy. Second, the Chinese have so far resisted the kind of currency appreciation to which West Germany and Japan consented. We conclude that Chimerica cannot persist for much longer in its present form. As in the 1970s, sizeable changes in exchange rates are needed to rebalance the world economy. A continuation of Chimerica at a time of dollar devaluation would give rise to new and dangerous distortions in the global economy.
Diaphragm Activity and Function During Mechanical Ventilation
No full textPrevious studies suggest that mechanical ventilation (MV) can injure the diaphragm, potentially prolonging ventilator dependence. However, there are many potential insults to diaphragm function during critical illness and the extent to which diaphragm dysfunction is attributable to ventilation remains undefined in the clinical setting. We hypothesized that diaphragm inactivity and/or injurious diaphragm loading during MV mediate diaphragm injury in the clinical setting. To test this hypothesis, we first evaluated the feasibility, validity and reproducibility of novel methods for monitoring the diaphragm in the clinical setting. We found that neuromuscular coupling (NMC), a measure of diaphragm function, is influenced by inspiratory effort, airway flow and diaphragm motion during inspiration and that NMC varies considerably over time in healthy volunteers. We also found that right hemidiaphragm thickness can be measured reproducibly by ultrasound and that increasing diaphragm thickness during inspiration reflects active contractile activity rather than passive chest wall expansion. Subsequently, in a large prospective cohort study (n=107) we demonstrated that diaphragm thickness varies considerably over time in relation to the level of inspiratory effort. Changes in muscle thickness were associated with impaired muscle function. Finally, in a preliminary clinical study (n=10) we confirmed the feasibility of selectively enrolling patients at high risk of prolonged MV and of measuring diaphragm activity and patient-ventilator dyssynchrony on an hourly basis commencing shortly after intubation. We conclude that ultrasound is a useful clinical tool to monitor the diaphragm during MV; NMC measurement requires further standardization and validation. MV likely causes significant diaphragm injury in patients and titrating ventilatory support to maintain normal levels of inspiratory effort may protect the diaphragm from injury during MV. A detailed description of patient exposure to diaphragm inactivity and injurious loading during MV is feasible; such observations could inform the design of muscle-protective ventilation strategies.Ph.D
Risk factors for extubation failure in patients following a successful spontaneous breathing trial
No full textBACKGROUND:
To assess the factors associated with reintubation in patients who had successfully passed a spontaneous breathing trial.
METHODS:
We used logistic regression and recursive partitioning analyses of prospectively collected clinical data from adults admitted to ICUs of 37 hospitals in eight countries, who had undergone invasive mechanical ventilation for > 48 h and were deemed ready for extubation.
RESULTS:
Extubation failure occurred in 121 of the 900 patients (13.4%). The logistic regression analysis identified the following associations with reintubation: rapid shallow breathing index (RSBI) [odds ratio (OR), 1.009 per unit; 95% confidence interval (CI), 1.003 to 1.015]; positive fluid balance (OR, 1.70; 95% CI, 1.15 to 2.53); and pneumonia as the reason for initiating mechanical ventilation (OR, 1.77; 95% CI, 1.10 to 2.84). The recursive partitioning analysis allowed the separation of patients into different risk groups for extubation failure: (1) RSBI of > 57 breaths/L/min and positive fluid balance (OR, 3.0; 95% CI, 1.8 to 4.8); (2) RSBI of 57 breaths/L/min and negative fluid balance (OR, 1.4; 95% CI, 0.8 to 2.5); and (4) RSBI of < 57 breaths/L/min (OR, 1 [reference value]).
CONCLUSIONS:
Among routinely measured clinical variables, RSBI, positive fluid balance 24 h prior to extubation, and pneumonia at the initiation of ventilation were the best predictors of extubation failure. However, the combined predictive ability of these variables was wea
Venovenous extracorporeal membrane oxygenation in patients with acute covid-19 associated respiratory failure: comparative effectiveness study
No full textOBJECTIVETo estimate the effect of extracorporeal membrane oxygenation (ECMO) compared with conventional mechanical ventilation on outcomes of patients with covid-19 associated respiratory failure.DESIGNObservational study.SETTING30 countries across five continents, 3 January 2020 to 29 August 2021.PARTICIPANTS7345 adults admitted to the intensive care unit with clinically suspected or laboratory confirmed SARSCoV-2 infection.INTERVENTIONSECMO in patients with a partial pressure of arterial oxygen to fraction of inspired oxygen (PaO2/FiO(2) ratio 15 cmH(2)O during the first 10 days of mechanical ventilation.CONCLUSIONSECMO was associated with a reduction in mortality in selected adults with covid-19 associated respiratory failure. Age, severity of hypoxaemia, and duration and intensity of mechanical ventilation were found to be modifiers of treatment effectiveness and should be considered when deciding to initiate ECMO in patients with covid-19
The "Thin Film Of Gold": Monetary Rules and Policy Credibility In Developing Countries
No full textThis paper asks whether developing countries can reap credibility gains from submitting policy to a strict monetary rule. Following earlier work, we look at the gold standard era (1880-1914) as a "natural experiment" to test whether adoption of a rule-based monetary framework such as the gold standard increased policy credibility. On the basis of the largest possible dataset covering almost sixty independent and colonial borrowers in the London market, we challenge the traditional view that gold standard adherence worked as a credible commitment mechanism that was rewarded by financial markets with lower borrowing costs. We demonstrate that in the poor periphery -- where policy credibility is a particularly acute problem -- the market looked behind "the thin film of gold". Our results point to a dichotomy: whereas country risk premia fell after gold adoption in developed countries, there were no credibility gains in the volatile economic and political environments of developing countries. History shows that monetary policy rules are no short-cut to credibility in situations where vulnerability to economic and political shocks, not time-inconsistency, are overarching concerns for investors.
A Q Methodological Study of the Support Valued by Students with English as an Additional Language
No full textThis study investigated the viewpoints of students with English as an Additional Language (EAL). Specifically, I used Q methodology to highlight some of the viewpoints of learners with EAL on the strategies used by adults to support them in school. A Q set of 46 statements was produced, with each statement describing a strategy for supporting learners with EAL. The Q set was developed firstly through the use of two focus groups involving 11 students aged between 9 and 15, secondly through consultation with relevant professionals, and thirdly through a literature review. I then asked 30 participants aged between 9 and 18 to express their viewpoint through a Q sort exercise, by ranking strategies according to helpfulness. Factor analysis was used to identify viewpoints which were common to a group of participants. In the results section I present each of the emerging viewpoints as a Q sort arrangement, and also as a written description produced by interpreting the factor analysis results. The four viewpoints which emerge are discussed, along with the implications for professionals needing to provide personalised support, and also stay in touch with the viewpoints of individual students with EAL in school. It is hoped that the current research will address the need within the literature to include the voice of students with EAL in planning for their education
Monitoring and Controlling Respiratory Effort in Acute Hypoxemic Respiratory Failure
No full textVentilation and sedation are used to manage acute hypoxemic respiratory failure (AHRF), but their individual and interactive effects on respiratory effort (|∆Pes|) and lung-distending pressure (∆PL,dyn) are unknown. This is a secondary analysis of a trial of a lung- and diaphragm-protection strategy in patients with AHRF, where ventilator settings and sedation were systematically manipulated to optimize |∆Pes| and ∆PL,dyn. The study showed that propofol attenuates |∆Pes| and ∆PL,dyn. Sedation with fentanyl was associated with lower respiratory drive, but not with lower respiratory effort. Increasing inspiratory pressure also attenuated |∆Pes|, but not ∆PL,dyn. The effect of inspiratory pressure varied according to the propofol dose: increasing inspiratory pressure resulted in higher ∆PL,dyn in patients receiving higher propofol dose. Patients on VV-ECMO had lower |∆Pes| and required lower propofol dose to control respiratory effort. This study highlights the complex interactions between interventions to modulate respiratory effort and provides insights on optimal management strategies.M.Sc.2023-12-26 00:00:0
High-frequency oscillatory ventilation in adults: handle with care
No full textAbstract
In the previous issue of Critical Care, Gu and colleagues reported the results of a systematic review and meta-analysis of randomized trials comparing high-frequency oscillatory ventilation (HFOV) with conventional ventilation in adults with acute respiratory distress syndrome (ARDS). In contrast to findings of prior meta-analyses, their main finding was that, despite reducing risks of oxygenation failure, HFOV does not improve survival in adults with ARDS
Financial Crises, 1880-1913: The Role of Foreign Currency Debt
No full textWhat is the role of foreign currency debt in precipitating financial crises? In this paper we assemble data for nearly 30 countries between 1880 and 1913 and examine debt crises, currency crises, banking crises and twin crises. We pay special attention to the role of foreign currency and gold clause debt, currency mismatches and debt intolerance. We find fairly robust evidence that more foreign currency debt leads to a higher chance of having a debt crisis or a banking crisis. However, a key finding is that countries with noticeably different backgrounds, and strong institutions such as Australia, Canada, New Zealand, Norway, and the US deftly managed their exposure to hard currency debt, generally avoided having too many crises and never had severe financial meltdowns. Moreover, a strong reserve position matched up to hard currency liabilities seems to be correlated with a lower likelihood of a debt crisis, currency crisis or a banking crisis. This strengthens the evidence for the hypothesis that foreign currency debt is dangerous when mis-managed. We also see that countries with previous default histories seem prone to debt crises even at seemingly low debt to revenue ratios. Finally we discuss the robustness of these results to local idiosyncrasies and the implications from this representative historical sample.
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