Anaesthesia With or Without Rocuronium in Intubation and Intraoperative Nerve-monitoring During Thyroid Surgery.

In this randomized controlled trial the investigators want to assess if, compared to controls, the administration of one single low-dose of rocuronium would increase the occurrence of absent or weak (i.e. amplitude \<100 μV) signal at V1 and R1, indicating a residual NMBA activity. In addition, we also recorded: 1) the occurrence of difficult laryngoscopy; 2) the time-to-intubation; 3) the occurrence of difficult intubation; 4) the number of intubation attempts; 5) the intubation failure rate; 6) the need for oxygenation between intubation attempts; 7) the lowest peripheral saturation in oxygen (SpO2); 8) the number of severe desaturations; 9) the time-to-V1 and 10) the number of post-surgical complications.

The lesion of laryngeal nerves is one of the most severe complications, which could be observed during the thyroid and parathyroid surgery. The recent clinical review, relative the problem and based on 27 articles and 25000 patients involved, shows that the incidence of the temporary paralysis of the recurrent laryngeal nerve (RLN) was 9,8%, and the permanent paralysis of the nerve was 2,3%. In the most cases the typical reasons of lesions of RLN are: section, clamping, electrothermic damage, stretching or entrapment of the nerve. The lesions of the RLN could lead to voice disturbance, breathing and swallow alterations. It is also one of the most frequent reasons for legal medicine disputes.

The intraoperative nerve-monitoring (IONM) of the RLN and of the external branch of superior laryngeal nerve (EBSLN) has been suggested as an instrument to limit the risk of post-operative damaging. It was introduced in the 60's, and the method was accepted by surgical community with the great enthusiasm. This technique is based on employment of special electrode, which transmits electrical signal of low amperage and stimulates directly the RLN, evaluating the muscle response. The stimulation of the EBSLN is commonly identified by contractions of cricothyroid muscle. On the other hand, the stimulation of the RLN leads to the response of the relative vocal cord, which could be palpated or observed by means of electromyography (EMG).

For implementation of the good IONM the collaboration between the surgeons and the anaesthesiologists is strongly required, e.g. the vocal cords are been monitored during the operation by means of laryngoscopy or a special endotracheal tube.

The particular role for the anaesthesiologists during the operation is the way of using of muscle relaxants. In fact, long-action agents should be generally avoided to prevent the absence of adequate muscle response, during the IONM.

Eligibility Criteria:
Inclusion Criteria:

* Elective surgery of the thyroid with the use of Intra-Operative Neuromuscular Monitoring (IONM)

Exclusion Criteria:

* Patients who suffer from paralysis of vocal cords or diseases of neuromuscular system.
* Patients with a history of allergy to anaesthetic drugs.
* Patients who has a high possibility of difficult intubation due to one the following criteria: a) interdental distance \< 20 mm; b) marked upper teeth protrusion (mandibular prognathism), which is not possible to correct; c) thyromental distance ≤ 60 mm; d) Mallampati class 4; e) macroglossia with marked micrognathia; f) fixed neck flection; g) severe scar tissue or post radiation fibrosis of the tongue.
* Patients who has a high possibility of difficult intubation due to two of the following criteria, associated with each other: a) interdental distance \< 35 mm; b) moderate prognathism or retrgnathia; c) mentohyoid distance \< 40 mm; d) thyromental distance ≤ 65 mm; e) Mallampati class 2-3; f) reduced head-neck flexion and extension; g) Body Mass Index (BMI) \> 30 kg/m2.