New horizons (Baltimore, Md.)
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Paralysis via neuromuscular blockade in ICU patients requires mechanical ventilation. This review historically addresses the technological advances and scientific information upon which ventilatory management concepts are based, with special emphasis on the influence such concepts have had on the use of neuromuscular blocking agents. Specific reference is made to the scientific information and technological advances leading to the newer concepts of ventilatory management. ⋯ However, adequate analgesia, amnesia, and sedation are required. For patients with severe lung disease, alveolar overdistention and hyperoxia should be avoided and may be best accomplished by total ventilatory support techniques, such as pressure control. Total ventilatory support requires neuromuscular blockade and may not provide eucapnic ventilation.
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Review
Persistent paralysis in critically ill patients after the use of neuromuscular blocking agents.
Neuromuscular blocking agents (NMBAs), an important part of the pharmacologic armamentarium of the intensivist, have a long and admirable history of safety when used in the operating room for periods of time (almost always < 12 hrs). Since 1985, dozens of medical journals have reported a multitude of studies on persistent paralysis when these same agents are exported from the operating room to the ICU. Most of these reports are case presentations of patients who failed to move for days to weeks after discontinuation of NMBAs. ⋯ This article sorts through the issues surrounding persistent paralysis, and defines it as a short-term and a long-term problem. The short-term problem seems to have a pharmacologic explanation that is not difficult to correct. The long-term problem is much more complex and may have a toxic explanation that may also be more difficult to manage.
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Neuromuscular blocking agents (NMBAs) are commonly prescribed as adjunct therapy for many critically ill patients. Controversy exists regarding the appropriate long-term use of these agents, particularly since there are severe potential clinical consequences. The expanded use of NMBAs has had a significant effect on the cost of ICU care. ⋯ This article reviews some of the indicative economic issues surrounding the use of sedatives, analgesics, and NMBAs in the critical care arena. Understanding the pharmacokinetic and pharmacodynamic differences of these agents can aid in drug selection and route of administration. Appropriate drug selection can influence the pharmacoeconomics of these agents in the ICU.
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Reported survival rates for severe adult respiratory distress syndrome (ARDS) patients vary from 9% to 84%. Animal study results have suggested that application of the high pressures needed to deliver commonly used tidal volumes (10 to 15 mL/kg) may induce an overexpansion of the remaining small fraction of compliant ARDS lung still capable of gas exchange. Conventional ventilatory therapy might thus superimpose an iatrogenic lung injury on the ARDS lung. ⋯ By standardizing therapy, protocols may significantly reduce the random and nonrandom noise (bias) introduced into the clinical environment by clinical care team members. This is especially important fo the many pertinent clinical questions addressed by clinical trials that cannot be double blinded. Conclusions from protocol-controlled clinical trials should be more credible and more likely to lead to action than those of the past.
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While all neuromuscular blocking agents (NMBAs) effectively interrupt neuromuscular transmission, it must be emphasized that these drugs are completely devoid of analgesic, sedative, or amnestic properties. The increasing use of NMBAs in the ICU requires familiarity with their basic pharmacologic properties, as well as an appreciation of potential problems associated with chronic (> 24 hrs) neuromuscular blockade. Although NMBAs possess an impressive safety record, the majority of recommendations for neuromuscular blocker use in the ICU are extrapolated from short-term perioperative studies in healthy patients. ⋯ Prolonged weakness after discontinuation of NMBAs is increasingly recognized after these agents are used for extended periods. This phenomenon may be related to alterations in the pharmacokinetics and pharmacodynamics, along with altered physiology of the neuromuscular junction, nervous system, or muscle, or other undefined toxic effects. A sound knowledge of the basic physiology of the neuromuscular junction, neuromuscular blocker pharmacology, and standard techniques to assess the degree of neuromuscular blockade provides the rationale for drug selection when paralysis is indicated in ICU patients.