Resp Care
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Airway pressure release ventilation (APRV) and bi-level positive airway pressure (BIPAP) are proposed to reduce patient work of breathing (WOB) sufficiently and to obviate issues related to patient-ventilator synchrony, so that spontaneous breathing can be maintained throughout the course of acute lung injury (ALI). Thus, APRV/BIPAP should reduce requirements for sedation and muscle paralysis, and thereby reduce the duration of mechanical ventilation. Only 17 human, animal, or lung-model studies have examined these claims, either directly or indirectly. ⋯ Furthermore, the theoretical benefits of APRV, in terms of controlling patient WOB, appear particularly limited when lung-protective ventilation is used for ALI patients with high minute ventilation demand. Future research should focus on issues of WOB and synchrony, so that reasonable ventilation protocols can be devised to test clinical outcomes against traditional modes. To date, low-level evidence suggests that promoting spontaneous breathing with APRV/BIPAP may not be appropriate in patients with relatively severe ALI/ARDS.
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Over the past decade, concepts of control of breathing have increasingly moved from being theoretical concepts to "real world" applied science. The purpose of this review is to examine the basics of control of breathing, discuss the bidirectional relationship between control of breathing and mechanical ventilation, and critically assess the application of this knowledge at the patient's bedside. ⋯ The evolution of newer technologies, faster real-time computing abilities, and miniaturization of ventilator technology can bring the concepts of control of breathing to the bedside and benefit the critically ill patient. However, market forces, lack of scientific data, lack of research funding, and regulatory obstacles need to be surmounted.
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There is arguably more evidence to support the use of noninvasive ventilation (NIV) than any other practice related to the care of patients with acute respiratory failure. Despite this strong evidence base, NIV seems to be under-utilized and the failure rate (need for intubation) may be as high as 40%. Some of these failures potentially relate to asynchrony, although the relationship between asynchrony and NIV failure has not been well studied. ⋯ Thus, reducing the leak related to the interface and using a ventilator with good leak compensation should reduce the rate of asynchrony. Asynchronies can also be related to the underlying disease process. This paper reviews issues related to asynchrony during NIV and suggests strategies that might be used to correct asynchrony when it occurs.
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Sedation has become an important part of critical care practice in minimizing patient discomfort and agitation during mechanical ventilation. Pain, anxiety, and delirium form a triad of factors that can lead to agitation. Achieving and maintaining an optimal level of comfort and safety in the intensive care unit plays an essential part in caring for critically ill patients. ⋯ The goal of therapy should be directed toward a specific indication, not simply to provide restraint. Standard rating scales and unit-based guidelines facilitate the proper use of sedation and neuromuscular blocking agents. The goal of sedation is a calm, comfortable patient who can easily be aroused and who can tolerate mechanical ventilation and procedures required for their care.
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Since the early 1970s there has been an ongoing debate regarding the wisdom of promoting unassisted spontaneous breathing throughout the course of critical illness in patients with severe respiratory failure. The basis of this debate has focused on the clinical relevance of opposite problems. Historically, the term "disuse atrophy" has described a situation wherein sustained inactivity of the respiratory muscles (ie, passive ventilation) results in deconditioning and weakness. ⋯ Regardless, the clinical implications of this research strongly suggest that passive mechanical ventilation should be avoided whenever possible. However, promotion of unassisted spontaneous breathing in the acute phase of critical illness also may carry a substantial risk of respiratory muscle injury and weakness. Use of mechanical ventilation modes in a manner that induces spontaneous breathing effort, while simultaneously reducing the work load on the respiratory muscles, is probably sufficient to minimize both problems.