Synopsis: Wide variations exist in monitoring practices for the use of peripheral nerve stimulators and the frequency of monitoring during neuromuscular blockade.
Source: Kleinpell R, et al. Am J Crit Care 1996;5: 449-454.
To examine practice patterns of critical care nurses who care for patients during neuromuscular blockade, Kleinpell and colleagues surveyed a randomized, national sample of critical care nurses. The 744 respondents practiced in hospitals ranging in size from 30-1200 beds and ICUs ranging in size from 2-98 beds. The mean number of patients treated with neuromuscular blockade in these ICUs was 6.8 ± 9.1 per month and the mean duration of paralysis was 4.1 ± 3.4 days. The most common indications for neuromuscular blockade were to assist mechanical ventilation and to reduce oxygen consumption.
Most respondents (85%) reported that patients were routinely monitored for pain and anxiety. Depth of neuromuscular blockade was monitored using clinical assessment (31%), peripheral nerve stimulators (16%), or both (52%). When a peripheral nerve stimulator was used to monitor patients, more than half (58%) of the sample reported using baseline responses to train-of-four stimuli for monitoring. The amount of current (in milliamperes) used for stimulation was determined by clinical judgement (39%), unit policy (29%), supramaximal stimulation (18%), or physician order (5%). There was wide variation in the number of twitches used for titrating drug administration, with responses including all options (i.e., 0/4 [6%], 1/4 [48%], 2/4 [36%], 3/4 [5%] and 4/4 [3%]).
There was also substantial variability in monitoring frequency (i.e., before a drip change [50%], before a bolus [27%], every 30-60 minutes [42%], every hour [23%], every 2 hours [22%], every 4 hours [36%] and longer intervals [14%]). Nurses performed monitoring most often (92%), with other options including the resident, attending physician, or anesthesiologist.
COMMENT BY LESLIE A. HOFFMAN, RN, PhD
Adequate analgesia is especially important for patients who receive neuromuscular blocking agents because the paralysis induced by these agents causes patients to appear calm and relaxed when, in fact, they may be alert and aware. In 1989, a survey of health professionals indicated that 62% believed these agents reduced anxiety and 20% believed they relieved pain, (Pain 1989;37:315). These assertions are false. In the current study, 85% of respondents indicated that patients routinely received medications for pain and anxiety during neuromuscular blockade. While this is an improvement, 1.3% of respondents reported that neither type of medication was routinely administered during neuromuscular blockade.
Complications of neuromuscular blockade were once thought to be rare events of limited significance. It is now known that some patients who receive a neuromuscular blocking agent will remain profoundly weak long after the drug is discontinued and, in some cases, experience persistent muscle paralysis. Two groups of patients appear to be at particular risk: patients in renal failure and patients treated concomitantly with a muscle relaxant and repeated doses of a corticosteroid. Additional risk factors are believed to include long-term continuous administration and unintentional overdosing. Despite recommendations to limit treatment duration, use of these drugs ranged from 1 to 63 days. Most protocols recommend titrating drug administration to one or two twitches of a train-of-four using a peripheral nerve stimulator. In this study, 14% of respondents reported titrating dosage to other ranges, including 0 (excessive) and 3/4 of 4/4 (inadequate). Others (31%) reported using clinical assessment alone, which may provide an inaccurate assessment.
These responses indicate that improper monitoring still exists, an outcome which may reflect the limited amount of research conducted to identify optimum practice. Further research is needed to identify the best ways to prevent adverse effects of these drugs and strategies for educating critical care nurses about state-of-the-art care.
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