This is a randomized, cross over, experimental trial in which carotid body function will be evaluated in 35 healthy subjects during partial muscle relaxation and after recovery from muscle relaxation

Inclusion Criteria:

* age > 18 years

Exclusion Criteria:

• BMI index > 30 kg/m2
• Known or suspected neuromuscular disorders impairing neuromuscular function;
• Allergies to muscle relaxants, anesthetics or narcotics;
• A (family) history of malignant hyperthermia or any other muscle disease;
• Any neurological or psychiatric illness (including a history of anxiety).
• ASA class 3 or higher
• Gastro-oesophageal regurgitation