Resp Care
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Comparative Study
Performance comparison of nebulizer designs: constant-output, breath-enhanced, and dosimetric.
Design differences among pneumatically powered, small-volume nebulizers affect drug disposition (percentage of the dose delivered to the patient, lost to deposition in the equipment, and lost via exhalation to ambient air) and thus affect drug availability and efficacy. ⋯ The nebulizers we tested differ significantly in overall drug disposition. The dosimetric AeroEclipse provided the largest inhaled drug mass and the lowest loss to ambient air, with the test conditions we used. method.
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Comparative Study
Laboratory evaluation of 4 brands of endotracheal tube cuff inflator.
Routine measurement of endotracheal tube (ETT) cuff pressure is a standard in respiratory care, and several devices are available for measuring ETT cuff pressure. Yet an informed choice in the buying process is hindered by the present paucity of unbiased, comparative data. ⋯ The 4 cuff inflators tested differ in bias and precision and none of the devices accurately measure cuff pressure. Cuff inflator manufacturers should design an accurate yet reasonably priced device to inflate ETT cuffs, and ideally that device should allow cuff-pressure checks without decreasing cuff pressure. In the meanwhile clinicians may opt to use my proposed cuff-pressure measurement technique, which minimizes the loss of cuff pressure during cuff-pressure checks and provides more accurate cuff-pressure measurements.
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Comparative Study
Characteristics of demand oxygen delivery systems: maximum output and setting recommendations.
Demand oxygen delivery systems (DODS) allot oxygen by interrupting the oxygen flow during exhalation, when it would mostly be wasted. Because DODS conserve oxygen by various methods, there are important performance differences between DODS. We studied certain performance factors that have not previously been carefully examined. ⋯ DODS settings were not equivalent to continuous-flow oxygen in a bench model assessment; with equivalent settings the DODS tended to deliver greater F(I)O(2) than did continuous-flow oxygen. The maximum output capacity differed markedly among the DODS, and the user should know the device's capacity. A volume-referenced setting system for DODS should be adopted that would allow more predictable oxygen prescription and delivery via DODS.
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The control of breathing in patients with chronic obstructive pulmonary disease (COPD) follows the same basic principles as in normal subjects, both awake and asleep, with an expected lower feedback response during sleep. This impacts nocturnal gas exchange and sleep quality most profoundly in patients with more severe COPD, as multiple factors come into play. Hypoventilation causes the most important gas-exchange alteration in COPD patients, leading to hypercapnia and hypoxemia, especially during rapid-eye-movement sleep, when marked respiratory muscle atonia occurs. ⋯ In the presence of more profound daytime hypercapnia, polysomnography should be considered (over nocturnal pulse oximetry) to rule out other co-existing sleep-related breathing disorders such as obstructive sleep apnea (overlap syndrome) and obesity hypoventilation syndrome. Present consensus guidelines provide insight into the proper use of oxygen, continuous positive airway pressure, and nocturnal noninvasive positive-pressure ventilation for those conditions, but several issues remain contentious. In order to provide optimal therapy to patients, the clinician must take into account certain reimbursement and implementation-process obstacles and the guidelines for treatment and coverage criteria.
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Noninvasive positive-pressure ventilation (NPPV) should be considered a standard of care to treat COPD exacerbations in selected patients, because NPPV markedly reduces the need for intubation and improves outcomes, including lowering complication and mortality rates and shortening hospital stay. Weaker evidence indicates that NPPV is beneficial for COPD patients suffering respiratory failure precipitated by superimposed pneumonia or postoperative complications, to allow earlier extubation, to avoid re-intubation in patients who fail extubation, or to assist do-not-intubate patients. NPPV patient-selection guidelines help to identify patients who need ventilatory assistance and exclude patients who are too ill to safely use NPPV. ⋯ For severe stable COPD, preliminary evidence suggests that NPPV might improve daytime and nocturnal gas exchange, increase sleep duration, improve quality of life, and possibly reduce the need for hospitalization, but further study is needed. There is consensus, but without strong supportive evidence, that COPD patients who have substantial daytime hypercapnia and superimposed nocturnal hypoventilation are the most likely to benefit from NPPV. Adherence to NPPV is problematic among patients with severe stable COPD.