This study evaluates three different neuromuscular monitoring devices (acceleromyography, one- or three-dimensional, and electromyography) with regard to their precision to detect residual paralysis after injection of neuromuscular blocking agents and recurrence of paralysis after administration of reversal agents in a clinical setting.

Neuromuscular blocking agents (NMBAs) are routinely used as standard part of a modern, balanced anesthesia regime. A residual duration of action exceeding the end of surgery, also called residual neuromuscular paralysis, is a common undesired side effect and increases the risk for postoperative pulmonary complications such as aspiration or pneumonia delaying patients' discharge from the post-anesthesia care unit. To limit the incidence of residual paralysis in daily anesthesia care, quantitative neuromuscular monitoring is recommended after injection of NMBAs. If a residual effect of a NMBA is detected at the end of surgery, reversal agents such as cholinesterase inhibitors, e.g. neostigmine or a selective relaxant binding agent, e.g. sugammadex can be administered. However, if reversal agents are not adequately dosed, the risk for a residual neuromuscular blockade re-occurs. Accordingly, neuromuscular monitoring is also useful to control the action of the administered reversal agents.

Although several techniques of neuromuscular monitoring are established in clinical practice, electromyography (EMG) and acceleromyography (AMG) are the most common quantitative neuromuscular monitoring devices. Electromyography, the gold standard for detecting residual neuromuscular block, is based on measuring summarized spikes of evoked muscle contractions. Acceleromyography measuring the acceleration of evoked muscle contraction is also commercially available and easy to use. This acceleration, however, can be measured both one-dimensionally and three-dimensionally.

This study evaluates the three described neuromuscular monitoring devices with regard to their precision to detect residual paralysis after administration of NMBAs and recurrence of neuromuscular blockade after administration of reversal agents in a clinical setting. We plan to include and randomize a total of 200 patients. The study participants will be recruited from patients scheduled for surgery at the Klinikum rechts der Isar der Technischen Universität München, Munich, Germany. In each patient, acceleromyography (either one- or three-dimensional) will be compared with the calibrated electromyography. The findings will help to indicate which neuromuscular monitoring device is most suitable for detecting residual paralysis and recurrent neuromuscular blockade.

Inclusion Criteria:

• Patients ASA physical status I-III
• Patients older than 18 years
• General anesthesia with the use of the neuromuscular blocking agent rocuronium
• Expected duration of surgery more than 2 hours
• Patients having given informed consent to the study

Exclusion Criteria:

• Known or suspected allergy towards anesthetics/sugammadex or rocuronium
• Pregnant and breastfeeding women
• Known or suspected neuromuscular disease (Multiple sclerosis, myasthenia gravis)
• Anatomic and functional malformations with expected difficult intubation
• body mass index >35kg/m2
• Contraindication for the use of rocuronium or sugammadex
• Malignant hyperthermia
• Patients with a legal guardian