The purpose is to calculate the time for an optimal recovery (T4/T1 > 0.9) from the moment when 2 responses to double burst stimulation are visually identical and this for 95% of patients.

Neuromuscular monitoring is a basic monitoring for all curarised patients. Acceleromiography is used to supervise neuromuscular blockade and allow measuring in an objective and quantitative manner the curarisation level during surgery and phase of recovery from neuromuscular blockade. Various parameters are usually measured during surgery:

• T4/T1 ratio: ratio between the 4th and 1st response to "train of four" stimulation (TOF, 4 stimulations of 0.2 ms in 2 s). Neuromuscular recovery is considered appropriate if T4/T1 ratio is > 0.9
• Double burst stimulation (DBS): 2 short tetanic stimulations separated by an interval of 750 ms.

It is known that when DBSs induce the same visual and/or tactile response, T4/T1 recovery time is > 0.6. However, for an optimal recovery, T4/T1 ratio must be > 0.9.

This study will analyze the interval between the moment when DBSs are visually identical and the T4/T1 ratio is > 0.9, from anesthesia sheet of patients undergone surgery with tracheal intubation curarisation.

Results will define a minimum time to have an optimal recovery after having visually identical DBS responses.

Inclusion Criteria:

• ASA score 1-3
• Needing a surgery with tracheal intubation curarisation

Exclusion Criteria:

• none

Patient curarised at Nancy Hospital