Intraoperative assessment of atracurium-induced neuromuscular block using double burst stimulation

Monitoring neuromuscular blockade in the intensive care unit: the peripheral nerve stimulator

Traditionally, neuromuscular blocking agents (NMBAs) have been administered in the operating room as an adjunct to anesthetics. Recent studies in the United States have indicated that 98% of the anesthesiologists and critical care nurses surveyed use NMBAs at least occasionally. When monitoring the use of NMBAs, a combination of clinical monitoring and peripheral nerve stimulator monitoring has been recommended. However, the most effective techniques have yet to be described. Understanding the complexities of NMBAs and the absolute need for accurate monitoring techniques is imperative for clinicians. The purpose of this literature review is to evaluate current literature regarding monitoring techniques of NMBAs and to guide the advanced practice nurse's role in critical care.

Response to double-burst appears before response to train-of-four stimulation during recovery from non-depolarizing neuromuscular blockade

BACKGROUND

Double-burst stimulation (DBS) it a relatively new nerve stimulation mode introduced for improved manual detection of residual neuromuscular blockade. Previous studies have shown that DBS3,3 50/50 (3 stimuli at 50 Hz followed 0.75 seconds later by 3 stimuli at 50 Hz) can detect deeper degrees of neuromuscular blockade than train-of-four (TOF) stimulation.

AIM

The aim of the present study was to examine if DBS3,3 80/40 (3 stimuli at 80 Hz followed 0.750 s later by 3 stimuli at 40 Hz) can detect even deeper degrees of neuromuscular blockade than DBS3,3 50/50 and to determine the time lapse from reappearance of response to each of the two DBS modes until reappearance of response to the TOF mode of nerve stimulation.

METHODS

The study comprised 20 women undergoing gynaecological surgery and anaesthetised with fentanyl, thiopentone, halothane, and nitrous oxide. Neuromuscular transmission was monitored by using mechanomyography and stimulation of the ulnar nerve. Atracurium was used for neuromuscular blockade.

RESULTS

Elapsed time from reappearance of response to DBS3,3 80/40 and DBS3,3 50/50 to reappearance of response to TOF stimulation was 459 +/- 196 (mean +/- SD) and 360 +/- 150 seconds, respectively, (P < 0.05).

CONCLUSIONS

DBS3,3 80/40 is capable of detecting deeper degrees of blockade than DBS3,3 50/50, which again is capable of detecting deeper degrees of blockade than TOF.

Double burst monitoring during surgical degrees of neuromuscular blockade: a comparison with train-of-four

With double burst stimulation (DBS) it is possible to monitor more profound degrees of neuromuscular blockade than with train-of-four stimulation (TOF). It may therefore be indicated to change between DBS and TOF stimulation during moderate to profound degrees of neuromuscular blockade. Consequently, the aim of the study was to evaluate and compare the twitch height of the first twitch (D1) in DBS and the twitch height of the first twitch (T1) in TOF stimulation during moderate to profound degrees of neuromuscular blockade. Thirty-three patients scheduled for gynaecological laparotomy under general anaesthesia were studied. Mechanomyography was used for neuromuscular monitoring. The T1 twitch height before atracurium was administered served as the control twitch height (T1 control). T1 control was considered as 100%. A constant degree of neuromuscular blockade was maintained at a T1 twitch height at a point between 4 and 11% of T1 control, using a continuous infusion of atracurium. Sequences of 16 DBS and 16 TOF stimulations were given. Two different DBS patterns were examined: DBS3,350/50, (3 stimuli at 50 Hz followed 0.75 sec later by 3 stimuli at 50 Hz), and DBS3,380/40, (3 stimuli at 80 Hz followed 0.75 sec later by 3 stimuli at 40 Hz). The data were analysed by the method described by Bland and Altman. The D1 repeatability coefficients of 1.72% for DBS3,350/50 and 1.20% for DBS3,380/40 were significantly greater than the repeatability coefficient of 1.02% for T1 (p <0.05). The D1 bias of 16.7% for DBS3,350/50 was significantly less than the D1 bias of 25.7% for DBS3,380/40 (p <0.05). The limits of agreement between D1 and T1 were 0.1 to 33.3% for DBS3,350/50 and 2.9 to 48.5% for DBS3,380/40.

IN CONCLUSION

The repeatability of responses to DBS and TOF stimulations during moderate to profound degrees of neuromuscular blockade where only one twitch is consistently present is satisfactory. The responses to DBS were greater than responses to TOF as indicated by a positive bias of DBS. The limits of agreement between DBS and TOF responses were so wide that they cannot be used interchangeably.

Comparison of tactile and mechanomyographical assessment of response to double burst and train-of-four stimulation during moderate and profound neuromuscular blockade

It is common clinical practice to estimate the degree of neuromuscular blockade by tactile evaluation of twitch responses. The aim of the present study was to evaluate the use of tactile responses of adductor pollicis to double-burst stimulation (DBS) and train-of-four (TOF) peripheral nerve stimulation for monitoring moderate and profound levels of neuromuscular blockade. The study comprised 44 women scheduled for gynaecological laparotomy and anaesthetised with midazolam, fentanyl, thiopentone, halothane, nitrous oxide and atracurium. The tactile responses of the adductor pollicis were compared with mechanomyographical measurements in the contra lateral arm during recovery from neuromuscular blockade. The observers (anaesthetic nurses) of the tactile responses were blinded with regard to the stimulation pattern and the mechanomyographical measurements. The time from injection of the initial dose of atracurium until tactile reappearance of the first twitch in DBS (D1), was 24.6 (0-39.8) min, median (range). This was more rapid than the time until tactile reappearance of the first twitch in TOF (T1) 32.8 (18.2-43.4) min (P < 0.05). The median time from tactile reappearance of D1 until T1 recovered to 15% of the control twitch height was longer than the median time from tactile reappearance of T1 (14.6 versus 10.5 min) (P < 0.05). One or two responses to DBS or TOF were often felt before any responses had been detected mechanomyographically in the contralateral arm. When three or four responses to TOF were felt, responses were always detected mechanomyographically. It is concluded that tactile evaluation of responses ot DBS stimulation can estimate deeper levels of blockade than tactile evaluation of responses to TOF.

Double burst stimulation for monitoring neuromuscular blockade for tracheal intubation

Responses to double burst stimulation were palpated every 15 s after intravenous administration of vecuronium 0.2 mg.kg-1 in 60 adult patients under anaesthesia. Intubating conditions and neuromuscular responses to tracheal intubation were assessed at disappearance of one or both palpable responses to double burst stimulation in groups of 30 patients randomly divided, although in group A patients, tracheal intubation could be performed at disappearance of one palpable response to double burst stimulation; 27 out of 30 patients (90%) had mild to moderate bucking on intubation. In this group, only five patients (16.66%) had good intubating conditions. In group B, where tracheal intubation was attempted at disappearance of both palpable responses, intubating conditions were good in 28 out of 30 patients (93.33%) and there was no response to tracheal intubation in 26 out of 30 patients (86.66%). Palpation of evoked response to double burst stimulation can be used to predict intubating conditions and neuromuscular response to tracheal intubation with nondepolarising muscle relaxants such as vecuronium.