Atelectasis
Conditions
Keywords
Atelectasis, Fresh gas flow, Prevention, Oxygenation, Anaesthesia
Brief summary
Atelectasis is common during and after general anesthesia. Atelectasis develops early if preoxygenation with 100% oxygen is used and continuously used during induction until endotracheal intubation. The investigators hypothesize that a rapid anti-preoxygenation maneuver immediately after confirming a successful intubation, reduces the area of atelectasis as investigated by computed tomography compared to a standard procedure.
Interventions
Handling of the airway during induction and intubation is performed in a conventional manner. Initial ventilatory settings are also done in a conventional manner. As soon as correct position of the endotracheal tube is confirmed, controlled ventilation is started with a tidal volume of 7 mL/kg ideal body weight, PEEP 6 or 8 cm H2O (8 if BMI \>25) and a respiratory frequency of 10. The fresh gas flow is set to 1 Liter per minute with an oxygen mixture of 40%, aiming for an inspired FiO2 of 30-35%. Unless the patient´s SpO2 falls below 90%, the FiO2 remains unchanged throughout the procedure.
Handling of the airway during induction and intubation is performed in a conventional manner. Immediately after confirming a successful intubation, the effect of preoxygenation is eliminated with a fresh gas flow of 10 L/min of air, delivered with volume controlled ventilation consisting of tidal volumes of approximately 15 ml/kg ideal body weight, a positive expiratory pressure of 10 cm H20 and a respiratory frequency of 10. As soon as the end tidal O2 reaches 25%, the ventilator settings are adjusted to normal values (same as in the control group), i.e. tidal volume 7 mL/kg ideal body weight, PEEP 6 or 8 cm H2O (8 if BMI \>25). The mixture of oxygen in the fresh gas is increased to 40% and the fresh gas flow is set to 1 Liter per minute, aiming for an inspired FiO2 of 30-35%. Unless the patient´s SpO2 falls below 90%, the FiO2 remains unchanged throughout the procedure.
Sponsors
Study design
Eligibility
Inclusion criteria
* Healthy patients, American Society of Anesthesiology (ASA) I-II * Patients scheduled for orthopaedic day case surgery in general anaesthesia
Exclusion criteria
* ASA class III or higher * Body Mass Index (BMI) 30 or higher * Arterial oxygen saturation (SpO2) \<94% breathing air * Chronic Obstructive Pulmonary Disease (COPD) * Ischemic heart disease * Haemoglobin \<100g/L * Known or anticipated difficult airway and/or intubation * Active smokers and ex-smokers with a history of more than 6 pack years * Need for interscalene or supraclavicular regional anaesthesia with risk of phrenic nerve paralysis
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Atelectasis | Within 1-2 hours, just before emergence from anesthesia | The area of atelectasis in the lungs is assessed by computed tomography (CT) 10 mm above the dome of the right diaphragm and expressed in cm2 and as % of the total lung area in the particular scan. |
Secondary
| Measure | Time frame |
|---|---|
| Arterial blood gases | Within 2-3 hours perioperatively |
Countries
Sweden