Oxygenation Test During General Anesthesia

Region Västmanland40 enrolled

Overview

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.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

SINGLE

Enrollment

Conditions

Morbid Obesity

Interventions

During pre oxygenation and induction of anesthesia 100 % oxygen is used with a continuous positive airway pressure of 10 cmH2O, during maintenance of anesthesia a positive endexpiratory pressure of 10 cm H20 is used with controlled volume ventilation aiming at an end tidal carbon dioxide (CO2) level of 5 %. During emergence from anesthesia 100 % oxygen is used.

CPAP and 31% oxygenPROCEDURE

During pre oxygenation and induction of anesthesia 100 % oxygen is used with a continuous positive airway pressure of 10 cm H2O, during maintenance of anesthesia a positive endexpiratory pressure of 10 cm H20 is used with controlled volume ventilation aiming at an end tidal CO2 level of 5 %. During emergence from anesthesia 31 % inspiratory oxygen or the inspiratory oxygen level needed to achieve a SpO2 of at least 96 % (if 31 % oxygen is not enough), is used.

Eligibility

Sex: ALLMin age: 18 YearsMax age: 50 Years

Medical Language ↔ Plain English

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

Outcomes

Primary Outcomes

Change in peripheral O2 saturation(SpO2)during and 1 hour after anesthesia in comparison to awake before anesthesia.

During anesthesia SpO2 is measured at three different levels of oxygen; 21, 26 and 31 % respectively as long as SpO2 does not go lower than 87 % and compared to SpO2 immediately before anesthesia. SpO2 breathing air one hour after anesthesia is compared to SpO2 before anesthesia.

Time frame: Change in SpO2 from 5 min before start of anesthesia, to 5 min after intubation, 5 min before extubation and 1 hour after extubation.

Secondary Outcomes

Arterial blood gas values for saturation (SaO2)

During anesthesia SaO2 is measured at three different levels of oxygen; 21, 26 and 31 % respectively as long as SpO2 (sic! does not go lower than 87 % and compared to SaO2 immediately before anesthesia. SaO2 breathing air one hour after anesthesia is compared to SaO2 before anesthesia.

Time frame: 5 min before anesthesia, 5 min after intubation, 5 min before extubation and 1 hour after anesthesia.

Arterial oxygen tension (PaO2)

During anesthesia PaO2 is measured at three different levels of oxygen; 21, 26 and 31 % respectively as long as SpO2 (sic) does not go lower than 87 % and compared to PaO2 immediately before anesthesia. PaO2 breathing air one hour after anesthesia is compared to PaO2 before anesthesia.

Time frame: 5 min before start of anesthesia, 5 min after intubation, 5 min before extubation and 1 hour after extubation.