Airway Effects of PEEP During Anesthesia Induction.

Study Overview
=================
Brief Summary
-----------------
This study investigates airway effects of PEEP during maskventilation at anesthesia induction. Four patient groups will be ventilated with different PEEP and driving pressures to evaluate time to open airway after start of positive pressure maskventilation during anesthesia induction.

Detailed Description
-----------------
The use of continuous positive pressure (CPAP/PEEP) during pre-oxygenation and mask-ventilation in patients undergoing anesthesia induction is increasing. Continuous positive pressures have several respiratory benefits with well-documented data on both spontaneously breathing patients and intubated patients. However the effects of PEEP on anesthetized patients during mask-ventilation is poorly investigated. In a previous trial the that the investigators conducted, a PEEP-level of 10 cmH2O during mask ventilation after anesthesia induction surprisingly delayed time to alveolar ventilation compared to ZEEP. In order to investigate this phenomenon, four groups of patients will be compared during preoxygenation and mask ventilation after anesthesia induction. Each group consisting of 30 patients will be pre-oxygenated and mask ventilated with different CPAP/PEEP levels and different driving pressures. Time to open airway is measured as number of respiratory cycles until detection of CO2 on the capnograph.

Official Title
-----------------
Airway Effects of PEEP During Anesthesia Induction.

Conditions
-----------------
Airway Management, Positive End Expiratory Pressure, Mask-ventilation, Anesthesia Induction

Intervention / Treatment
-----------------
* Procedure: PEEP-level, driving pressure


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: ≥ 18- ≤ 65 years male or female. Elective surgery under general anesthesia ASA-classification 1-3 Signed and dated informed consent Exclusion Criteria: BMI > 30 Predicted difficult mask-ventilation Known hiatus hernia or GERD

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 65 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: 0 CPAP/ 0 PEEP, driving pressure 10<br>Patients will be preoxygenated with a CPAP-level of 0 cmH2O and after anesthesia induction, mask-ventilated with ZEEP and a driving pressure of 10 cmH2O./PEEP-level, driving pressure | Procedure: PEEP-level, driving pressure<br>* Different levels of PEEP and different levels of driving pressures during mask-ventilation at anesthesia induction.<br>|
| Other: 0 CPAP/ 0 PEEP driving pressure 20<br>Patients will be pre-oxygenated with a CPAP-level of 0 cmH2O and after anesthesia induction, mask-ventilated with ZEEP and a driving pressure of 20 cmH2O./PEEP-level, driving pressure | Procedure: PEEP-level, driving pressure<br>* Different levels of PEEP and different levels of driving pressures during mask-ventilation at anesthesia induction.<br>|
| Other: 10 CPAP / 10 PEEP, driving pressure 10<br>Patients will be pre-oxygenated with a CPAP-level of 10 cmH2O and after anesthesia induction, mask-ventilated with PEEP 10 cmH2O and a driving pressure of 10 cmH2O./PEEP-level, driving pressure | Procedure: PEEP-level, driving pressure<br>* Different levels of PEEP and different levels of driving pressures during mask-ventilation at anesthesia induction.<br>|
| Other: 10 CPAP/ 0 PEEP, driving pressure 10<br>Patients will be pre-oxygenated with a CPAP-level of 10 cmH2O and after anesthesia induction, mask-ventilated with ZEEP and a driving pressure of 10 cmH2O./PEEP-level, driving pressure | Procedure: PEEP-level, driving pressure<br>* Different levels of PEEP and different levels of driving pressures during mask-ventilation at anesthesia induction.<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Time to open airway | Time to open airway depending on ventilatory settings | 20 minutes |