Ventilation Strategy Reduces Postoperative Atelectasis

Not Applicable

Withdrawn

• Conditions: Pulmonary Atelectasis
• Interventions: Procedure: CPAP/PEEP and 30 % oxygen; Procedure: No CPAP/PEEP and 100 % oxygen

• Registration Number: NCT01911923
• Lead Sponsor: Region Västmanland

Brief Summary

Atelectasis is common during and after general anesthesia. The investigators hypothesized that a ventilation strategy with a combination of 1) continuous positive airway pressure (CPAP) or positive end-expiratory pressure (PEEP) and 2) a reduced end-expiratory oxygen fraction (FETO2) before commencing mask ventilation with CPAP after extubation would reduce the area of postoperative atelectasis.

Detailed Description

During general anesthesia, the combination of reduced functional residual capacity (FRC), high inspiratory oxygen fraction (FIO2), and airway closure are the main factors implicated in the atelectasis, shunt and shunt-like effects that account for the majority of the impaired oxygenation seen during general anesthesia.

Previous studies have shown that formation of atelectasis during preoxygenation and induction of anesthesia can be avoided by adding a continuous positive airway pressure (CPAP) followed by a positive end-expiratory pressure (PEEP).During emergence from anesthesia, high concentrations of oxygen predispose to atelectasis formation. Even a recruitment maneuver, followed by ventilation with 100% oxygen with a PEEP/CPAP of 10 cm H2O until extubation, failed to improve postoperative oxygenation compared with that achieved with zero end-expiratory pressure (ZEEP).This failure may have been caused by the presence of lung regions with high oxygen concentrations.

The investigators hypothesized that by inducing and discontinuing anesthesia during CPAP/PEEP and deliberately reducing FIO2 after extubation, postoperative atelectasis would be reduced compared with standard protocols. To test our hypothesis, the investigators studied 1) a control group with no CPAP/PEEP and a FIO2 of 1.0 while breathing spontaneously after extubation, and 2) an intervention group that was on CPAP/PEEP of 6 cmH2O from induction to extubation and that received an FIO2 of 1.0 until extubation and then an FIO2 of 0.3 via a facemask while on CPAP after extubation.

Study Timeline

• Study First Submitted: 2013-07-26
• Study First Submitted QC: 2013-07-29
• Study First Posted: 2013-07-30
• Study Start: 2013-08
• Primary Completion: 2013-11
• Study Completion: 2013-11
• Status Verified: 2014-08
• Last Update Submitted: 2014-08-25
• Last Update Posted: 2014-08-26

Recruitment & Eligibility

• Status: WITHDRAWN
• Sex: All
• Target Recruitment: Not specified

Inclusion Criteria

1. Adult patients up to 75 years of age.
2. American Society of Anesthesiologists (ASA) physical status class I-III.
3. Be able to climb two flight of stairs without stopping.
4. SpO2 of ≥ 94% when breathing air in the supine position.
5. A body mass index (BMI, weight in kilograms divided by the square of the height in meters) of < 31.

Exclusion Criteria

1. Patients with chronic obstructive pulmonary disease.
2. Smokers.
3. Ex smokers if smoked more than 5 pack years.
4. Overt heart failure
5. Known or predicted difficult intubation.

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
CPAP/PEEP and 30 % oxygen	CPAP/PEEP and 30 % oxygen	This is the intervention group
No CPAP/PEEP and 100 % oxygen	No CPAP/PEEP and 100 % oxygen	This is the control group

Primary Outcome Measures

Name	Time	Method
Area of atelectasis	30 minutes	The area of atelectasis is investigated by computed tomography of the lungs postoperatively

Secondary Outcome Measures

Name	Time	Method
Peripheral oxygen saturation (SpO2)	2 hours	SpO2 is assessed immediately after extubation and then continuously postoperatively

Trial Locations

Locations (1)

Västmanlands sjukhus Köping; 🇸🇪 Köping, Västmanland, Sweden