Dose-response relationship of rocuronium: a comparison of electromyographic vs. acceleromyographic-derived values

The Influence of Electromyographic on Electroencephalogram-Based Monitoring: Putting the Forearm on the Forehead

BACKGROUND

Monitoring the electroencephalogram (EEG) during general anesthesia can help to safely navigate the patient through the procedure by avoiding too deep or light anesthetic levels. In daily clinical practice, the EEG is recorded from the forehead and available neuromonitoring systems translate the EEG information into an index inversely correlating with the anesthetic level. Electrode placement on the forehead can lead to an influence of electromyographic (EMG) activity on the recorded signal in patients without neuromuscular blockade (NMB). A separation of EEG and EMG in the clinical setting is difficult because both signals share an overlapping frequency range. Previous research showed that indices decreased when EMG was absent in awake volunteers with NMB. Here, we investigated to what extent the indices changed, when EEG recorded during surgery with NMB agents was superimposed with EMG.

METHODS

We recorded EMG from the flexor muscles of the forearm of 18 healthy volunteers with a CONOX monitor during different activity settings, that is, during contraction using a grip strengthener and during active diversion (relaxed arm). Both the forehead and forearm muscles are striated muscles. The recorded EMG was normalized by z -scoring and added to the EEG in different amplification steps. The EEG was recorded during anesthesia with NMB. We replayed these combined EEG and EMG signals to different neuromonitoring systems, that is, bispectral index (BIS), CONOX with qCON and qNOX, and entropy module with state entropy (SE) and response entropy (RE). We used the Friedman test and a Tukey-Kramer post hoc correction for statistical analysis.

RESULTS

The indices of all neuromonitoring systems significantly increased when the EEG was superimposed with the contraction EMG and with high EMG amplitudes, the monitors returned invalid values, representative of artifact contamination. When replaying the EEG being superimposed with "relaxed" EMG, the qCON and BIS showed significant increases, but not SE and RE. For SE and RE, we observed an increased number of invalid values.

CONCLUSIONS

With our approach, we could show that EMG activity during contraction and resting state can influence the neuromonitoring systems. This knowledge may help to improve EEG-based patient monitoring in the future and help the anesthesiologist to use the neuromonitoring systems with more knowledge regarding their function.

High-dose rocuronium-induced paralysis of the adductor pollicis muscle facilitates detection of the timing for tracheal intubation in elderly patients: a randomized double-blind study

Purpose

Methods

Results

Conclusions

Comparison of clinical validation of acceleromyography and electromyography in children who were administered rocuronium during general anesthesia: a prospective double-blinded randomized study

Background

Electromyography and acceleromyography are common neuromuscular monitoring devices. However, questions still remain regarding the use of acceleromyography in children. This study compared the calibration success rates and intubation conditions in children after obtaining the maximal blockade depending on each of the devices

Methods

Children, 3 to 6 years old, were randomly allocated to the TOF-Watch SX acceleromyography group or the NMT electromyography group. The induction was performed with propofol, fentanyl, and rocuronium. The bispectral index and 1 Hz single twitch were monitored during observation. The calibration of the each device was begun when the BIS dropped to 60. After successful calibration, rocuronium 0.6 mg/kg was injected. A tracheal intubation was performed when the twitch height suppressed to 0. The rocuronium onset time (time from administration to the maximal depression of twitch height) and intubating conditions were rated in a blinded manner.

Results

There was no difference in the calibration success rates between the two groups; and the calibration time in the electromyography group (16.7 ± 11.0 seconds) was shorter than the acceleromyography group (28.1 ± 13.4 seconds, P = 0.012). The rocuronium onset time of the electromyography group (73.6 ± 18.9 seconds) was longer than the acceleromyography group (63.9 ± 18.8 seconds, P = 0.042) and the intubation condition of the electromyography group (2.27 ± 0.65) was better than the acceleromyography group (1.86 ± 0.50, P = 0.007).

Conclusions

Electromyography offers a better compromise than acceleromyography with respect to the duration of calibration process and surrogate for the optimal time of tracheal intubation in children.

Pharmacodynamic modelling of rocuronium in adolescents with Duchenne muscular dystrophy

BACKGROUND AND OBJECTIVE

Studies with rocuronium showed a delayed onset and prolonged recovery in patients with Duchenne muscular dystrophy (DMD). The objective of this study was to identify the pharmacokinetic and/or pharmacodynamic origin of these alterations.

METHODS

Twenty-five male patients (15 with DMD, 10 controls, aged 10-18 years) were studied. Patients were anaesthetized with propofol and sufentanil. Neuromuscular transmission was monitored by acceleromyography. Patients received a single intravenous dose of 0.3 mg kg(-1) rocuronium. In five patients of the DMD group, pharmacokinetic modelling was performed from arterial rocuronium concentrations. The time course of neuromuscular block was analysed with a sigmoid E(max) model including an effect compartment.

RESULTS

The pharmacokinetics of rocuronium in DMD patients were Vc 63 +/- 14 ml kg(-1), Cl 3.0 +/- 1.0 ml min(-1) kg(-1), half-lives 2.0 +/- 0.6, 20 +/- 10 and 129 +/- 98 min, SE. For both the DMD and the control group, the time course of neuromuscular block could be described by a sigmoid E(max) model using the estimated pharmacokinetic parameters of the DMD group. In patients with DMD, the equilibration between the central and effect compartment was significantly slower (T(1/2)ke0: 9.7 +/- 0.3 vs. 1.3 +/- 0.1 min) and the EC(50) was significantly smaller (512 +/- 20 vs. 1170 +/- 64 ng ml(-1)), whereas the ED(50) was 0.16 +/- 0.02 mg kg(-1) in both groups.

CONCLUSION

The pharmacodynamics of rocuronium were significantly altered in patients with DMD, whereas the pharmacokinetics seemed to be similar to those in healthy adults. Patients with DMD were more sensitive with respect to effect site concentration but not with respect to dose.

Sugammadex: a novel agent for the reversal of neuromuscular blockade

To achieve spontaneous ventilation after completion of surgery, the nondepolarizing effects on skeletal muscle relaxation are often reversed by administration of an acetylcholinesterase inhibitor. However, these agents increase acetylcholine at both the neuromuscular junction and the muscarinic receptors. Therefore, coadministration of an anticholinergic agent is required to prevent parasympathetic adverse effects. In addition, a relative pharmacologic ceiling effect is seen with inhibition of acetylcholinesterase, necessitating some recovery of neuromuscular function before an acetylcholinesterase inhibitor is administered. Sugammadex is a new modified gamma-cyclodextrin compound under clinical investigation in the United States. It does not interact with cholinergic mechanisms to elicit reversal. Instead, it is a selective relaxant binding agent and acts by forming a 1:1 complex with steroidal nondepolarizing neuromuscular blockers in the plasma, lowering the effective concentration available at the receptor. Due to its selectivity, sugammadex does not inhibit the effects of nondepolarizing agents of the benzylisoquinolinium class. In contrast to acetylcholinesterase inhibition, sugammadex is effective even when administered during profound blockade, and it does not require coadministration of an anticholinergic agent. It provides a novel mechanism of action for reversal of the neuromuscular block induced by nondepolarizing aminosteroidal agents.