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

Neuromuscular blockade can be assessed accelerographically over the vastus medialis muscle in patients positioned prone

PURPOSE

To study accelerographic monitoring of neuromuscular blockade over the vastus medialis muscle in anesthetized patients in the prone position.

METHODS

Sixty adult patients were divided into four groups of 15: prone (P)-post-tetanic count (PTC), P-train-of-four (TOF), supine (S)-PTC or S-TOF group. In the P-PTC and P-TOF groups, the muscular branch of the femoral nerve was stimulated and the movement of the vastus medialis muscle was measured accelerographically. In the S-PTC and S-TOF groups, the depth of neuromuscular blockade was assessed mechanically at the thumb. After administration of vecuronium 0.1 mg.kg(-1), TOF stimuli were delivered every 20 sec in all groups. Onset of neuromuscular blockade (time from vecuronium to the minimum level of T1 (first response of TOF) was compared between the P-PTC or P-TOF group and S-PTC or S-TOF group. Recoveries of PTC and those of TOF were compared between the P-PTC and S-PTC groups and P-TOF and S-TOF groups, respectively.

RESULTS

Onset of neuromuscular blockade in the P-PTC or P-TOF group was shorter than in the S-PTC or S-TOF group (132 +/- 43 vs 233 +/- 40 sec, mean +/- SD, P < 0.001). Recoveries of PTC in the P-PTC and S-PTC groups followed a similar time course. Recoveries of T1/control in the P-TOF and S-TOF groups were also comparable. In contrast, train-of-four ratio (T4/T1, TOFR) in the P-TOF group was higher than in the S-TOF group 60-120 min after vecuronium (P < 0.05).

CONCLUSIONS

The degree of neuromuscular blockade can be assessed accelerographically over the vastus medialis muscle even when patients are in the prone position. When evaluated accelerographically over the vastus medialis muscle, onset of neuromuscular blockade is quicker and TOFR is higher than that assessed at the thumb.

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.

Recovery of post-tetanic and train-of-four responses at the first dorsal interosseous and adductor pollicis muscles in patients receiving vecuronium

PURPOSE

To compare recovery of accelographical responses to post-tetanic twitch (PTT) and train-of-four (TOF) stimuli obtained at the first dorsal interosseous muscle (DI) with those at the adductor pollicis muscle (AP) after administration of vecuronium 70 micrograms.kg-1.

METHODS

Sixty adult patients were randomly assigned to one of four groups: PTT-DI (n = 15), PTT-AP (n = 15), TOF-DI (n = 15), or TOF-AP (n = 15) group. In PTT-DI and PTT-AP groups, responses to PTT were measured accelographically at the DI and at the AP, respectively. In TOF-DI and TOF-AP groups, responses to TOF were measured at the DI and at the AP, respectively.

RESULTS

The T1/T0 (T0 = control) was greater in the TOF-DI than in TOF-AP group throughout recovery (P < 0.05), and the T4/T1 was greater in the TOF-DI than in TOF-AP group during the 30-40 min after vecuronium injection (P < 0.05). Time to the return of the first response to PTT (post-tetanic count(1), PTC1) was less in the PTT-DI than in the PTT-AP group (17.7 +/- 4.2 vs 21.7 +/- 5.6 min, mean +/- SD, P = 0.0341). The post-tetanic count PTC (number of single twitch stimuli in response to PTT) was greater in the PTT-DI than in the PTT-AP group during the 10-30 min after vecuronium (P < 0.05). Time to the return of T1 was less in the TOF-DI than in the TOF-AP group (23.1 +/- 6.0 vs 27.6 +/- 4.9 min, P = 0.0334).

CONCLUSION

Recovery of responses to PTT and TOF stimuli occurred earlier at the DI than at the AP.

Post-tetanic burst count: a stimulating pattern for profound neuromuscular blockade

The purpose of this study was to compare the pattern of recovery from vecuronium 0.07 mg.kg-1 induced neuromuscular blockade using post-tetanic burst count (PTBC)-(three short tetanic bursts of 0.2 msec duration every 20 msec given every second following a tetanus), and post-tetanic count (PTC)-(0.2 msec single twitch stimuli given every second following a tetanus) using an accelerometer in 60 adult patients during nitrous oxide-oxygen-isoflurane anaesthesia. In addition, the relationship among PTBC, PTC, and T1 (the 1st response in the train-of-four (TOF) stimulation) was examined to investigate whether the PTBC had an advantage over the PTC or TOF for evaluating intense neuromuscular blockade. The PTBC was greater than PTC during the 15-35 min after the administration of vecuronium (unpaired t test with Bonferroni's correction, P < 0.05). Time to the return of PTB response was shorter than that of PTT (17.7 +/- 3.2 vs 22.7 +/- 3.7 min, unpaired t test, P = 0.0005). Time from the return of PTB to that of T1 was longer than the time from the return of PTC to that of T1 (13.3 +/- 2.6 vs 9.2 +/- 2.8 min, unpaired t test, P = 0.0003). At the return of T1, PTBC was greater than PTC (14.3 +/- 6.9 vs 9.4 +/- 2.3, unpaired t test, P = 0.0153). These results suggest that, using PTBC, a more profound level of neuromuscular blockade can be evaluated than that using PTC.

Optimal stimulating current for train-of-four stimulation in conscious subjects

The purpose of this study was to determine the optimal stimulating current for train-of-four (TOF) monitoring with regard to the return of TOF response and the discomfort associated with TOF. Two variables were examined at 60, 50, 40, 30, and 20 mA: (1) times from administration of vecuronium 80 micrograms.kg-1 to returns of responses to TOF determined accelographically in 75 anaesthetised patients and (2) discomfort associated with TOF in 15 awake volunteers using visual analogue scale (VAS). Times to return of the first response to stimulation at 60, 50, 40, and 30 mA were not different (29.1 +/- 11.2, 30.1 +/- 12.0, 31.9 +/- 12.6, and 35.4 +/- 14.2 min, respectively, mean +/- SD). However, time to the return of the first response elicited at 20 mA (53.7 +/- 21.6) was longer than at higher currents (P < 0.05). Similarly, with regard to the second, third, and fourth responses, the time to the return at 20 mA was longer than at the other currents (P < 0.05). The VAS associated with TOF at 60, 50, 40, 30, and 20 mA were 7.3 +/- 1.9, 6.7 +/- 1.8, 6.0 +/- 2.0, 4.1 +/- 2.1, and 2.7 +/- 2.3, respectively. The VAS at 30 mA was less than at 60 and 50 mA (P < 0.05), and at 20 mA was less than at 60, 50, and 40 mA (P < 0.05). In conclusion it is suggested that, when testing conscious patients, 30 mA is the optimal stimulating current for TOF monitoring because it represents the best compromise of neuromuscular monitoring and patient discomfort.