Neuromuscular-blocking drugs - Use and misuse in the intensive care unit

Neuromuscular-blocking (NMB) drugs commonly are administered to critically ill patients in ICUs in the United States and Europe. Although NMB agents a re used frequently in ICU patients, their role in the intensive care settin g is not well defined. Most knowledge of NMB drugs has been extrapolated fr om the operating room in healthy patients or patients with single-organ fai lure. Patients receiving NMB agents in the ICU typically are afflicted by m ultiple-organ failure and are receiving a number of concomitant medications . The pharmacokinetic and pharmacodynamic effects of these drugs in this he terogeneous patient population are currently poorly understood. Few clinica l studies examining the use of muscle relaxants in ICU patients have been p ublished. At present, there are no formal guidelines to direct the clinicia n in the use of NMB agents in the critically ill patient. This article disc usses the indications for long-term neuromuscular blockade, the complicatio ns associated with the use of the NMB agents, and some of the specific agen ts commonly employed in the ICU. Recommendations about the use and monitori ng of NMB drugs based on available clinical data also are proposed. The frequency of use of NMB agents in the United States has been examined i n national surveys. Retrospective surveys of intensivists in 1991 and 1992 revealed that an average of 10 patients per unit per month required prolong ed neuromuscular blockade.(17,31) In a 1997 prospective study of 129 ICUs, drug administration data were collected for 5 consecutive days. During this study interval, 9.7% of the patients received an NMB drug.(61) A 3-month p rospective survey from the Mayo Clinic demonstrated that the use of NMB age nts varied widely among different ICUs. The chances of being admitted to an ICU and receiving a muscle relaxant ranged from 0% in the neurosurgical IC U to 14% in the neonatal ICU. On average, only one to two patients per ICU per month received an NMB drug.(45).