Comparison of Mechanomyographic 100 Versus 200 Hz 5 Second Tetanic Fade Ratios During Neuromuscular Block Recovery

MATERIALS AND METHODS Patient management The monocentric study protocol was approved before patients' inclusion by the Institutional Ethical Committee (CHU UCL Namur, Yvoir, Belgium, OM 050, under unique belgian registration number B0392022000035).

It was performed in accordance with the ethical standards of the Declaration of Helsinki and was included in the Clinical Trials Registry (XXX).

After obtaining written informed consent from all participants, 20 patients with American Society of Anesthesiologists (ASA) grades I to II (aged 18 to 65 years), who were scheduled to undergo rhinoplasty or rhinoseptoplasty under general anaesthesia, were included in the study. The exclusion criteria were pregnant or breastfeeding women, patients with renal or hepatic insufficiency, patients with neurological disorders, and any patient with a suspected allergy to the drugs used in the protocol or receiving medications that could interfere with neuromuscular transmission. The patient's height, weight, age, and sex were recorded in the protocol to define the population investigated.

The patients were conventionally monitored with a pulse oximeter, a three-lead electrocardiogram and a non-invasive blood pressure monitor scheduled in automatic mode at 5-minute intervals. An intravenous catheter was inserted into their forearm for crystalloid infusion (side at random). Neuromuscular transmission monitoring (NMTM) was set up according to a specific protocol.

Total intravenous anaesthesia was induced with continuous infusion of remifentanil 0.25 µg/kg/min and continuous infusion of propofol 1% to obtain theoretical plasma concentrations ranging from 3 to 6 µg/mL (Diprifusor Cardinal Health, Basingstoke, UK). Lidocaine 1 mg/kg was also given as an intravenous bolus. After loss of consciousness, manual ventilation was provided during NMTM calibration and the initial NMB baseline measurements. Then, rocuronium 0.45 mg/kg was administered. Non-invasive automatic blood pressure measurement was suspended during the neuromuscular onset to avoid dissimilar distribution of the rocuronium in the two arms. Tracheal intubation was performed when the TOF count reached zero. Automatic non-invasive blood pressure measurement was reactivated. Mechanical ventilation (closed circuit, 40% oxygen in air) maintained end-tidal CO2 within the normal range. Anesthesia was maintained with the continuous intravenous administration of remifentanil 0.15 µg/kg/min and propofol with a target plasma concentration of 2 to 4 µg/mL. Blankets prevented heat loss from the body and both arms, and the oropharyngeal temperature was kept stable. Postoperative analgesia was provided with paracetamol, tramadol and alizapride at the end of surgery.