OBJECTIVE:

To investigate facial nerve monitoring in patients receiving the partial nondepolarizing neuromuscular blocking agents (NMBAs), remifentanil and propofol.

METHODS:

Patients with normal facial function and advanced middle-ear disease were enrolled. For total intravenous anaesthesia (TIVA), propofol and remifentanil were infused as induction/maintenance anaesthesia. Stimulation thresholds and amplitudes were recorded at each train-of-four (TOF) nerve stimulation level. Time differences between start of TOF and electromyographic (EMG) amplitude decreases (Ti), and between complete recovery of TOF and EMG amplitudes (Tr), were calculated.

RESULTS:

Fifteen patients were enrolled. Mean ± SD Ti was 3.4 ± 1.28 min; Tr was 18.7 ± 4.41 min. Amplitude of stimulation was apparent mostly at TOF level 1. In most cases, no or a weak response (<100 µV) was observed at TOF 0. Mean ± SD threshold of electrical stimulation was 0.31 ± 0.10 mA at TOF 1. At TOF > 2, all cases showed EMG response on electrical stimulation.

CONCLUSIONS:

Induction of TIVA using propofol and remifentanil provided reliable conditions for delicate microsurgery. Minimal NMBA use, considered as producing TOF levels >1, was sufficient for facial nerve monitoring in neuro-otological surgery.

Neuromuscular blockers (NMBs) provide good conditions for endotracheal intubation and surgery. NMBs have been associated with higher morbidity and mortality, mainly due to post-operative residual neuromuscular block. This may become history with the advent of sugammadex - an antidote to the NMB rocuronium - which within 1-3 minutes neutralizes the effects of rocuronium. High-dose rocuronium is now an alternative to suxamethonium in acute or short procedures and in a situation, where ventilation/intubating cannot be performed, sugammadex can reverse the rocuronium blockade within minutes.

There have been no evidence-based comparisons of motor-evoked potential (MEP) monitoring with no and partial neuromuscular block (NMB). We compared the effects of different levels of NMB including no NMB on MEP parameters.MEP-monitored 120 patients undergoing neurosurgery were enrolled. The patients were randomly allocated to four groups: Group A was to maintain two train-of-four (TOF) counts; Group B was to maintain a T(1)/Tc of 0.5; Group C was to maintain a T(2)/Tc of 0.5 (T(1,2), first or second twitch height of TOF; Tc, control twitch height); Group D did not maintain NMB. The mean MEP amplitude, coefficient of variation (CV), the incidence of spontaneous respiration or movement, the efficacy of MEP, and haemodynamic parameters were compared.The median [inter-quartile range (IQR)] amplitudes of the left leg for Groups A, B, C, and D were 0.23 (0.15-0.57), 0.44 (0.19-0.79), 0.28 (0.15-0.75), and 0.75 (0.39-1.35) mV, respectively. The median (IQR) CVs of the left leg were 71.1 (56.9-88.8), 76.1 (54.2-93.1), 59.8 (48.6-95.6), and 25.2 (17.3-35.0), respectively. The differences between groups of the mean amplitudes of the left arm and both legs were statistically significant (Kruskal-Wallis test, P=0.011 for the left leg). For all limbs, the differences between groups of the CVs were significant (P<0.001, for the left leg). Other parameters were not different.If NMB is used during MEP monitoring, a target T(2)/Tc of 0.5 is recommended. In terms of the MEP amplitude and variability, no NMB was more desirable than any level of partial NMB.

The goal of this study is to investigate the incidence and risk factors of residual paralysis associated with single-dose intermediate-acting muscle relaxants (atracurium, vecuronium, rocuronium) during early postoperative period.Adult patients (ASA I and II) who received a single dose of vecuronium, atracurium or rocuronium during general anesthesia for elective surgical procedure were included in the study. Train-of-four (TOF) ratios under 0.9 were recorded as "postoperative residual neuromuscular block (PRNB)". Age, weight, gender, reversal, anesthesia duration, time for transfer to the recovery room after extubation were studied regarding with PRNB.84 patients were included in this study. 29 patients were received vecuronium, 28 patients were received atracurium and 27 patients were received rocuronium. Neostigmine was used for reversal in 49 patients (58.3%) at the end of the surgery. PRNB incidence (TOF < 0.9) was 13.1%. Based on the regression analysis, the only risk factor affecting PRNB was found as gender. PRNB risk was increased in women (OR: 7.250, 95%, CI: 1.019-51.593).In patients who have general anesthesia longer than one hour, "gender" may affect residual paralysis incidence associated with single-dose intermediate-acting muscle relaxants use.

Prolonged duration of action of rocuronium in an infant patient is rare. We report an unusual case of prolonged neuromuscular blockade with rocuronium in an infant undergoing cleft lip repair anesthetized with sevoflurane and management of the patient.

The benefits of spontaneous breathing over muscle paralysis have been proven mainly in mild lung injury; no one has yet evaluated the effects of spontaneous breathing in severe lung injury. We investigated the effects of spontaneous breathing in two different severities of lung injury compared with muscle paralysis.Prospective, randomized, animal study.University animal research laboratory.Twenty-eight New Zealand white rabbits.Rabbits were randomly divided into the mild lung injury (surfactant depletion) group or severe lung injury (surfactant depletion followed by injurious mechanical ventilation) group and ventilated with 4-hr low tidal volume ventilation with spontaneous breathing or without spontaneous breathing (prevented by a neuromuscular blocking agent). Inspiratory pressure was adjusted to control tidal volume to 5-7 mL/kg, maintaining a plateau pressure less than 30 cm H2O. Dynamic CT was used to evaluate changes in lung aeration and the regional distribution of tidal volume.In mild lung injury, spontaneous breathing improved oxygenation and lung aeration by redistribution of tidal volume to dependent lung regions. However, in severe lung injury, spontaneous breathing caused a significant increase in atelectasis with cyclic collapse. Because of the severity of lung injury, this group had higher plateau pressure and more excessive spontaneous breathing effort, resulting in the highest transpulmonary pressure and the highest driving pressure. Although no improvements in lung aeration were observed, muscle paralysis with severe lung injury resulted in better oxygenation, more even tidal ventilation, and less histological lung injury.In animals with mild lung injury, spontaneous breathing was beneficial to lung recruitment; however, in animals with severe lung injury, spontaneous breathing could worsen lung injury, and muscle paralysis might be more protective for injured lungs by preventing injuriously high transpulmonary pressure and high driving pressure.

Anaphylaxis during anesthesia is a rare but life-threatening event. Sugammadex is a recently introduced drug that was specifically designed for the reversal of rocuroium and vecuronium-induced neuromuscular block. We describe the cases of a 74-year-old man and a 29-year-old man who developed an anaphylactoid reaction to sugammadex, presenting with cardiovascular collapse. Initial management consisted of fluid administration and intermittent i.v. ephedrine, epinephrine, and hydrocortisone. The patients made uncomplicated recovery and were discharged.