The use of intravenous muscle relaxants during anaesthesia can significantly facilitate endotracheal intubation and reduce the chance of possible airway complications during intubation. Overall, muscle relaxants make anaesthesia safer. Quantitative measurement of neuromuscular block is essential when anaesthesiologists use muscle relaxants. It allows to avoid postoperative residual block complications such as upper airway obstruction, hypoxia, pharyngeal dysfunction, aspiration.

Unfortunately, quantitative monitoring of neuromuscular block is not routinely used in everyday practice - and this is particularly true in the infant and child population. In adults, the relative absence of easy-to-use and reliable monitors has led to the neglect of neuromuscular monitoring. One of the monitoring techniques suitable for this purpose is electromyography. This EMG-based instrument (TetraGraph ® ) measures the action potential of the musculus adductor pollicis or the musculus abductor digiti minimi muscles.

Clinical trials have shown that for quantitative monitoring of the effect of muscle relaxants, extubation is safe if the TOF ratio is 0.9. Some studies have shown that TOF ratio of 0.95 is necessary to reduce the risk of postoperative respiratory complications.

In this study, investigators will use an EMG-based neuromuscular monitor, the TetraGraph ®, and an electrode specially designed for the infant and child population to measure the muscle relaxant (rocuronium) effect of infants undergoing decompressive surgery for craniosynostosis, from the time of induction until the TOF ratio of 0.9 is reached, using inhaled anaesthetic or intravenous agent to maintain anaesthesia.

In adult population it has been clearly demonstrated that inhaled anaesthetics potentiate the effect of muscle relaxants during maintenance anaesthesia, whereas this effect is moderate or negligible when intravenous maintenance agents are used. There is limited literature on the efficacy of rocuronium in the infant population when anaesthesia is maintained with sevoflurane or propofol. The aim of present study is to improve postoperative patient safety in the infant population.

Infants undergoing anaesthesia for elective craniosynostosis surgery are included in the study. The surgical preparation, anaesthesia of the patients, will be carried out in all aspects according to the daily routine, i.e.: All infants will receive 0.1 mg/kg midazolam i.v. for pre-medication. In the operating theatre, a peripheral vein is provided. Precordial ECG, pulse oximetry, blood pressure measurement, end-expiratory CO 2 , end-expiratory oxygen measurement will be performed during the surgery.

Inclusion Criteria:

• 20 infants whose parents have given informed written consent to participate in the studies;
• Age: 3-12 months;

Exclusion Criteria:

• diseases affecting neuromuscular function (myopathies, severe liver and kidney failure);
• Lack of parental consent
• Known allergy to any of the products used