Articles: mechanical-ventilation.
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Standard mechanical insufflation-exsufflation (MI-E) therapy is applied with fast insufflation-exsufflation pressures to achieve high peak expiratory flows (PEF) and assist airway clearance. No attention is given to the resultant high peak inspiratory flows (PIF), although it may impair secretion removal. It has been proposed that an expiratory flow bias (ie, PEF higher than PIF) might be the key determinant for mucus clearance instead of the PEF alone. We examined the effects of 2 MI-E maneuvers, standard versus optimized, with fast and slow insufflation, respectively, along with different MI-E pressure settings on secretion displacement in 3 lung-impedance scenarios that simulated a patient on mechanical ventilation. ⋯ The optimized MI-E maneuver, applied with slow insufflation, resulted in a higher expiratory flow bias, which made the therapy more effective at moving mucus outward, compared with the standard MI-E maneuver, typically applied with fast insufflation.
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Comparative Study
Mechanical Ventilation-Related Safety Incidents in General Care Wards and ICU Settings.
Although the ICU is the most appropriate place to care for mechanically ventilated patients, a considerable number are ventilated in general medical care wards all over the world. However, adverse events focusing on mechanically ventilated patients in general care have not been explored. ⋯ Human-factor issues were the most frequent reasons in both settings, while knowledge-based error rates were higher in general care. Our results suggest that proper education and training is needed to minimize patient safety incidents in facilities without respiratory therapists.
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Diaphragm dysfunction develops frequently in ventilated intensive care unit (ICU) patients. Both disuse atrophy (ventilator over-assist) and high respiratory muscle effort (ventilator under-assist) seem to be involved. A strong rationale exists to monitor diaphragm effort and titrate support to maintain respiratory muscle activity within physiological limits. Diaphragm electromyography is used to quantify breathing effort and has been correlated with transdiaphragmatic pressure and esophageal pressure. The neuromuscular efficiency index (NME) can be used to estimate inspiratory effort, however its repeatability has not been investigated yet. Our goal is to evaluate NME repeatability during an end-expiratory occlusion (NMEoccl) and its use to estimate the pressure generated by the inspiratory muscles (Pmus). ⋯ Repeated measurements of NMEoccl exhibit high variability, limiting the ability of a single NMEoccl maneuver to estimate neuromuscular efficiency and therefore the pressure generated by the inspiratory muscles based on EAdi.
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The open lung approach (OLA) reportedly has lung-protective effects against acute respiratory distress syndrome (ARDS). Recently, lowering of the driving pressure (ΔP), rather than improvement in lung aeration per se, has come to be considered as the primary lung-protective mechanism of OLA. However, the driving pressure-independent protective effects of OLA have never been evaluated in experimental studies. We here evaluated whether OLA shows protective effects against experimental ARDS even when the ΔP is not lowered. ⋯ OLA shows protective effects against experimental ARDS, even when the ΔP is not decreased. In addition to reducing ΔP, maintaining lung aeration seems to be important for lung protection in ARDS.
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Arterial blood gas (ABG) analysis is the traditional method for measuring the partial pressure of carbon dioxide. In mechanically ventilated patients a continuous noninvasive monitoring of carbon dioxide would obviously be attractive. In the current study, we present a novel formula for noninvasive estimation of arterial carbon dioxide. ⋯ The mean difference between PaCO₂ and carbon dioxide with Formula 2 was 0.66 kPa (±SE 0.18). With a mixed linear model excluding cases with cardiorespiratory collapse, there was a significant difference between formulae (p < 0.001), as well as significant interaction between formulae and time (p < 0.001). In this preliminary animal study, this novel formula appears to have a reasonable agreement with PaCO₂ values measured with ABG analysis, but needs further validation in human patients.