Presence Of Electromyographic Activity Research Articles

Influence of neuromuscular block and reversal on bispectral index and NeuroSense values

Influence of neuromuscular block and reversal on bispectral index and NeuroSense values

Effect of sugammadex or neostigmine neuromuscular block reversal on bispectral index monitoring of propofol/remifentanil anaesthesia

Sugammadex is a modified γ-cyclodextrin with a novel mechanism of action for reversing the steroidal neuromuscular blocking agent rocuronium. Bispectral index (BIS) is an EEG-derived measure which can be sensitive to frontal electromyographic (EMG) artifacts. We compared BIS values before and after sugammadex or neostigmine neuromuscular block (NMB) reversal in patients with or without high EMG activity. During stable propofol/remifentanil anaesthesia and rocuronium-induced block, 48 patients were randomly allocated to receive sugammadex 4 mg kg(-1) or neostigmine 50 μg kg(-1)/glycopyrrolate 10 μg kg(-1), 10 min after the end of surgery. Five minutes after sugammadex administration, mean BIS 50.1 (10.3) increased (P=0.018) to 61.7 (7.9) in 11 patients with high EMG activity. In contrast, BIS 49.3 (4.9) remained at 51.9 (5.4) in 13 patients who had no EMG activity. Fifteen minutes after neostigmine administration, mean BIS 51.9 (8.1) increased (P=0.007) to 63.9 (8.1) in 13 patients who had reappearance of muscle activity. However, in 11 patients who had no EMG activity, BIS 52.3 (7.4) remained at 53.3 (6.8). There was no significant difference between the sugammadex and neostigmine groups over time. We have shown that reversal of NMB with sugammadex or neostigmine increased BIS values dependent on the presence of EMG activity. Thus, the effect of muscle activity reappearance during rocuronium NMB reversal spuriously increasing the BIS value should be taken into consideration when relying on BIS monitoring for evaluating propofol/remifentanil recovery.

Skin conductance or entropy for detection of non‐noxious stimulation during different clinical levels of sedation

State entropy (SE) measures electroencephalographic signals, whereas response entropy (RE) also includes frontal electromyographic activity. In the presence of electromyographic activity, the RE index is larger than the SE index, the difference being denoted as RE-Delta (RE-Delta= RE - SE). Skin conductance (SC) may be expressed by a slow reacting variable, the mean SC level, the derivate of the mean SC level (D-SC), the number of SC fluctuations (NSCF) or the amplitude of the SC fluctuations (ASCF), which directly shows skin sympathetic nerve activity. The goal of this study was to evaluate whether these SC and entropy variables could differentiate between the responses obtained to load sound stimuli at different sedation levels before the induction of general anaesthesia. Twenty women scheduled for gynaecological laparotomy were studied. The modified observer's assessment of alertness sedation (OAAS) was used to classify the patients' hypnotic levels. White sounds (98 dB) were given at OAAS level 5 without propofol, at OAAS levels 4-3 and 3-2 with propofol and at OAAS levels 3-2 and < 2 with propofol and remifentanil. RE and SE showed a steady decline from OAAS level 5 to level < 2 (P < 0.01). RE-Delta did not discriminate between any of the OAAS levels (P= NS). The mean SC level discriminated between OAAS levels 4-3 to < 2 (P < 0.01). D-SC discriminated between all the different OAAS levels (P < 0.01). NSCF discriminated between OAAS levels 5 to 3-2 (P < 0.05), but did not discriminate at OAAS level 3-2 between propofol alone or combined with remifentanil, or between OAAS level 3-2 and < 2. ASCF differentiated between OAAS levels 5 and 4 (P < 0.001) and OAAS levels 3-2 and < 2 (P < 0.05) only. RE, SE and D-SC showed a similar discrimination between sound responses at the different sedation levels.