Resp Care
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Mechanical ventilation has, since its introduction into clinical practice, undergone a major evolution from controlled ventilation to various modes of assisted ventilation. Neurally adjusted ventilatory assist (NAVA) is the newest development. The implementation of NAVA requires the introduction of a catheter to measure the electrical activity of the diaphragm (EA(di)). ⋯ With NAVA, the reliance on the EA(di) signal, together with an intact ventilatory drive and intact breathing reflexes, allows integration of the ventilator in the neuro-ventilatory coupling on a higher level than conventional ventilation modes. The simple monitoring of the EA(di) signal alone may provide the clinician with important information to guide ventilator management, especially during the weaning process. Although, until now, little evidence proves the superiority of NAVA on clinically relevant end points, it seems evident that patient populations (eg, COPD and small children) with major patient-ventilator asynchrony may benefit from this new ventilatory tool.
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The arterial partial pressure of CO(2) (P(aCO(2))) can be grossly estimated by the end-tidal partial pressure of CO(2) (P(ETCO(2))). This principle is used in SmartCare (Dräger, Lübeck, Germany), which is an automated closed-loop system that uses P(ETCO(2)) to estimate alveolar ventilation during mechanical ventilation. ⋯ Use of maximum P(ETCO(2)) reduces the difference between P(aCO(2)) and P(ETCO(2)) and improves SmartCare's classification of patient ventilatory status.
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Pressure support ventilation (PSV) should be applied so that the inspiratory muscles are unloaded appropriately. We developed a computerized advisory system that assesses the load on the inspiratory muscles to spontaneously inhale, reflected by the automatically and noninvasively measured work of breathing per minute, and tolerance for that load, reflected by spontaneous breathing frequency and tidal volume, in a fuzzy-logic algorithm that provides recommendations for setting PSV. We call this a load and tolerance strategy for determining PSV. ⋯ A load and tolerance strategy with a computerized PSV advisory system provided valid recommendations for setting PSV to unload the inspiratory muscles, and the recommendations were essentially the same as the recommendations from experienced critical-care RRTs. The PSV advisory system operates continuously and automatically and may be useful in clinical environments where experts are not always available.
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As the use of intravenous magnesium sulfate (MgSO(4)) for the treatment of refractory asthma is becoming more common, the incidence of MgSO(4)-related systemic hypotension is also rising. One option is to deliver MgSO(4) via aerosol, but compared to most inhaled medications, which are active in the microgram dose range, the MgSO(4) dose requirement is in the milligram range. This, along with inefficient aerosol delivery systems, may be the reason that some studies have found lack of efficacy with aerosol MgSO(4). In preparation for a multicenter study of inhaled MgSO(4) in asthmatic children 2-17 years old, we conducted an in vitro study to choose the best MgSO(4) nebulizer system that would be effective over the entire age range. ⋯ The Aeroneb Go with Idehaler was chosen for the multicenter clinical study.
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Mixing of nebulized drugs is common in real life, but its consequences on aerosol output and granulometry are poorly known. ⋯ Both the SideStream and VentStream-Pro have good aerosol performance in nebulizing budesonide or beclomethasone dipropionate alone, and when mixed with albuterol and ipratropium bromide.