During anesthetic induction, the relevance of neuromuscular blockade (NMB) onset monitoring cannot be asserted and its superiority over waiting for a fixed delay (corresponding to pharmacokinetic knowledge of the neuromuscular blocking agent used) has not been proven. However, many studies have shown a large inter-individual variability on the delay of the NMB onset. The main objective of othe investigator's study is to compare the quality of laryngoscopy during intubation between the NMB onset monitoring and the expectation of a fixed delay after curarization

French guidelines on curarization, updated in 2018, do not recommend the NMB onset monitoring due to a lack of data in the literature. Thus, the interest of monitoring cannot be asserted and its superiority over waiting for a fixed delay has not been proven.

Due to a large inter-individual variability on the delay of the NMB onset after administration of atracurium, the relevance of monitoring NMB during an anesthetic induction should be assessed to improve the quality of laryngoscopy.

In case of monitoring, the experts recommend monitoring the NMB onset at the corrugator supercilli because it reflects neuromuscular blockade at the laryngeal adductor muscles.

During the pre-anaesthetic visit, patients will be enrolled after inform consent.

Patients will be randomized in two groups, control group (waiting for a 3-minute delay after injection of atracurium) or monitoring group (waiting for the TOF ratio at 0 at the corrugator supercilli).

Anesthetic induction will be performed with sufentanil, propofol and atracurium. After laryngoscopy, the primary outcome will be evaluated using Copenhagen score.

Patients will be followed up until they leave the recovery room..

Inclusion Criteria:

• Adult patients (≥ 18 years), both sexes
• Any elective surgery requiring injection of atracurium
• Free patient, without guardianship or subordination
• Patients with a social security coverage
• Informed and signed consent after clear and fair information

Exclusion Criteria:

• Rapid sequence induction
• Predictable difficult intubation
• Use of a neuromuscular blockade agent other than atracurium
• Known contraindication to a neuromuscular blockade agent