Mask ventilation during induction of anesthesia can be improved by administration of neuromuscular blocking agents (NMBAs). NMBAs are usually administered after testing mask ventilation; however, muscle relaxants may improve mask ventilation and they do not alter mask ventilation. Thus, growing evidence suggests to administer muscle relaxants before testing mask ventilation. We will study different dosages of rocuronium; we assume that higher dosages of rocuronium will improve mask ventilation compared with lower dosages.

Mask ventilation during induction of anesthesia can be improved by administration of neuromuscular blocking agents (NMBAs). NMBAs are usually administered after testing mask ventilation; however, muscle relaxants may improve mask ventilation and they do not alter mask ventilation. Thus, growing evidence suggests to administer muscle relaxants before testing mask ventilation.We will administer rocuronium 0.3 mg/kg, 0.6 mg/kg, 0.9 mg/kg and saline (placebo group) before starting with mask ventilation. We will grade mask ventilation based on various scores before and after rocuronium application. Afterwards patient's tracheas will be intubated. We assess risk factors for difficult mask ventilation.

We hypothesize that rocuronium 0.9 mg/kg will be superior to rocuronium 0.3 mg/kg and saline.

Inclusion Criteria:

• patients with ASA I-III
• required tracheal intubation
• informed consent

Exclusion Criteria:

• known allergy against anesthetics
• known difficult airway