Clinical trial NCT01911923: Ventilation Strategy Reduces Postoperative Atelectasis
Official title: Reduction in Postoperative Atelectasis by Continuous Positive Airway Pressure and Low Oxygen Concentration After Endotracheal Extubation.
Study type: INTERVENTIONAL
Overall status: WITHDRAWN
Phase: NA
Conditions: Pulmonary Atelectasis
Lead sponsor: Region Västmanland
Sponsor class: OTHER
First posted: 2013-07-30
Enrollment: 0
Sex: ALL
Minimum age (years): 20
Maximum age (years): 75
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: TREATMENT

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.

Eligibility criteria: 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.

Primary outcomes:
measure: Area of atelectasis
timeFrame: 30 minutes
Secondary outcomes:
measure: Peripheral oxygen saturation (SpO2)
timeFrame: 2 hours
Other outcomes:
Locations:
city: Köping
country: Sweden
facility: Västmanlands sjukhus Köping
state: Västmanland
Study officials:
affiliation: Landstinget Vastmaland
name: Lennart Edmark, Md
role: PRINCIPAL_INVESTIGATOR
References: