Chapter 12

### DRUG OVERVIEW

Approximately 80 percent of critically ill intensive care patients require mechanical ventilation, thus administration of a one-time-only dose of a neuromuscular blocking agent (NMBA) is common. They are used to facilitate endotracheal intubation as they prevent laryngospasm and keep the patient from resisting the procedure. These agents should not be used, however, if the normalcy of the airway and the ability to successfully accomplish bag-mask ventilation and endotracheal intubation are questionable. Once intubated, only 1 percent to 15 percent of ICU patients are treated with continuous infusion or scheduled NMBAs (1%, surgical ICU; <10% medical ICU; ~15% trauma and pediatric ICU).1 Aggressive use of analgesia and sedation is essential initially, and NMBAs are reserved for patients who fail to meet desired goals despite maximum sedative therapy. The clinical practice guideline for sustained neuromuscular blockade published by the Society of Critical Care Medicine states that “NMBAs should be used in an adult patient in an ICU to manage ventilation, manage increased ICP, treat muscle spasms, and decrease oxygen consumption ONLY when all other means have been tried without success.”2

When used to manage ventilation, NMBAs allow improvement in pulmonary compliance. Neuromuscular blocking agents can assist ventilation therapy in at least three ways: (1) by reducing or eliminating spontaneous breathing; (2) preventing motor activity that might dislodge catheters, surgical dressings, or chest tubes; and (3) reducing oxygen consumption by patients with severely diminished cardiopulmonary function. However, the effect of neuromuscular blockade on ventilatory mechanics and chest wall compliance may be minimal in a patient who is maximally sedated. Although NMBAs are used in the mechanically ventilated patient, well-designed controlled trials do not exist that document improved patient outcomes when they are used to facilitate mechanical ventilation.1,2 Most reports are limited to case studies, small prospective open-label trials, and small randomized open-label and double-blind trials. In addition, none of these reports compared NMBAs to placebos.

NMBAs may be used postoperatively for several reasons. First, neuromuscular blockade can prevent unacceptably high oxygen consumption due to the profound shivering that frequently accompanies rewarming from hypothermia. This condition is particularly deleterious for hypoxic patients or those with a history of cardiovascular disease. Further, postoperative neuromuscular blockade may be a useful adjunct to promote healing of specific surgical wounds (e.g., vascular anastomosis, supraglottoplasty) by immobilizing the patient for a defined period. Immobilization may prove of particular benefit after tracheal resection and anastomosis or when closure of the wound has been difficult or disruptive and its loss of integrity would place the patient at great risk. Improved patient outcomes have been documented in the surgical population when NMBAs are utilized postoperatively for complicated ENT procedures (cricoid split and supraglottoplasty) when compared to historical controls.1

Apart from mechanical ventilation and postoperative indications, situations in the ICU that may warrant administration of NMBAs are diverse. Therapeutic paralysis has been used appropriately in treating tetanus, status epilepticus, and uncontrolled intracranial hypertension or intracranial pressure (ICP). ...

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