Clinical Trial: Ventilation Strategy Reduces Postoperative Atelectasis

Study Status: Withdrawn
Recruit Status: Withdrawn
Study Type: Interventional

Official Title: Reduction in Postoperative Atelectasis by Continuous Positive Airway Pressure and Low Oxygen Concentration After Endotracheal Extubation.

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 Summary:

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.


Sponsor: Landstinget Västmanland

Current Primary Outcome: Area of atelectasis [ Time Frame: 30 minutes ]

The area of atelectasis is investigated by computed tomography of the lungs postoperatively


Original Primary Outcome: Same as current

Current Secondary Outcome: Peripheral oxygen saturation (SpO2) [ Time Frame: 2 hours ]

SpO2 is assessed immediately after extubation and then continuously postoperatively


Original Secondary Outcome: Peripheral oxygen saturation (SpO2) [ Time Frame: 2 hours ]

SpO2 is assessed immediately after extubation and then continuouslypostoperatively


Information By: Landstinget Västmanland

Dates:
Date Received: July 26, 2013
Date Started: August 2013
Date Completion: November 2013
Last Updated: August 25, 2014
Last Verified: August 2014