Oxygenation Test During General Anesthesia

Application of Protective Ventilation Improves Oxygenation During and After Anesthesia. Is it Possible That a Special Procedure, an Oxygenation Test, Can Replace Arterial Blood Gases When Evaluating Oxygenation?

The study investigates if applying a special ventilatory strategy during anesthesia for laparoscopic gastric by pass, produces less atelectasis and better oxygenation in spite of using 100 % oxygen during pre oxygenation and induction of anesthesia. The study investigates oxygenation with blood gas samples but also with a new method that might give more information without the use of blood gas samples.

Primary: Oxygenation in patients with morbid obesity improves if preoxygenation, induction and maintenance of anesthesia is performed with either a continuous positive airway pressure (CPAP) or a positive end expiratory pressure (PEEP), respectively, of 10 cm H2O, in comparison to a technique without CPAP but with a PEEP of 10 cm H2O.

Secondary: The improved oxygenation during anesthesia can be prolonged inte the postoperative period if emergence from anesthesia is performed without high levels of oxygen.

Inclusion Criteria:

• Adult patients scheduled for elective surgery of Morbid Obesity.
• ASA 1-2. (ASA = American Society of Anesthesiologists classification).
• "Body mass index" (BMI) ≥ 35 but < 50

Exclusion Criteria:

• "ASA 3"
• Anticipated difficult intubation.
• Major bleeding.
• Problems with ventilation necessitating protocol aberrations.
• Obstructive sleep apnea syndrome with CPAP treatment at home.
• Angina Pectoris