End-Tidal CO2 (etCO2) and pH in the Correct Naso-gastric Tube Placement

Inclusion criteria: * Adult patients (\> 18 years) * Patients male and female * Patients intubated by oro- or naso-tracheal way * Post-induction curarized patients * Fasting patients (from at least 6 hours) Exclusion criteria: * Patient refusal * Patients with known bleeding diathesis / ongoing bleeding * Patients at risk of bleeding (defined as thrombocytes \<50 G/l, fibrinogen \<1.0 g/l, international normalized ratio (INR) \> 2.5, activated partial thromboplastin time (aPTT) \> 70 sec) * Patients with traumatic brain injury / Polytrauma * Patients with esophagus-tracheal fistulas or malformations of the ear, nose, and throat (ENT) sphere * Patients with current or previous radiotherapy of the ENT sphere * Patients unable to give their informed consent due to language barriers * Women who are pregnant