| Methods |
Parallel randomized controlled trial
High risk of bias |
| Participants |
40 participants randomly assigned Included: participants 65 years of age undergoing major open abdominal surgery Excluded: pulmonary disease with abnormalities in spirometry consistent with obstructive or restrictive pulmonary disease, active asthma (requiring chronic bronchodilator therapy), previous lung surgery, home oxygen therapy, significant cardiac dysfunction and BMI > 35 Age: years (mean 72.1, range (65‐88); 73.8, range (65‐88)) Sex distribution: M/F (16/4, 15/5) Country: United States |
| Interventions |
20 participants received PEEP (4 cm H2O) until the first recruitment manoeuvre. The recruitment manoeuvre was achieved by sequential increases in PEEP in 3 steps: 3 breaths (from 4 to 10 cm H2O), 3 breaths (15 cm H2O) and 10 breaths (20 cm H2O). After recruitment manoeuvre, level of PEEP was maintained at 12 cm H2O throughout the entire operation 20 participants received ZEEP without recruitment maneuvers |
| Outcomes |
Arterial blood gas parameters Oxygen efficiency: intraoperative and recovery room data Interleukins 6 and 8 Postoperative pulmonary complications Postoperative respiratory failure Length of hospital stay Mortality during admission |
| Notes |
SIngle centre
Atelectasis was analysed by chest x‐ray
Study authors defined postoperative respiratory failure as unanticipated mechanical ventilation for > 48 hours after operation or the need for reinstitution of mechanical or non‐invasive ventilation after extubation
Could be included in the following subgroup analyses: increased age (> 60 years)
We emailed the study authors to remove our doubts. Study authors provided data about length of hospital stay |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
High risk |
Quote: "Patients were randomized to one of the two ventilatory management strategies using a randomization schedule provided by the Division of Biostatistics"
Comment: not clear |
| Allocation concealment (selection bias) |
Unclear risk |
Not described |
| Blinding of participants and personnel (performance bias)
Mortality |
Unclear risk |
Not described |
| Blinding of participants and personnel (performance bias)
Oxigen efficiency ‐ PaO2/FiO2 |
Unclear risk |
Not described |
| Blinding of participants and personnel (performance bias)
Atelectasis |
Unclear risk |
Not described |
| Blinding of outcome assessment (detection bias)
Mortality |
Unclear risk |
Not described |
| Blinding of outcome assessment (detection bias)
Oxigen efficiency ‐ PaO2/FiO2 |
Unclear risk |
Not described |
| Blinding of outcome assessment (detection bias)
Atelectasis |
Unclear risk |
Not described |
| Incomplete outcome data (attrition bias)
All outcomes |
Low risk |
All participants analysed |
| Selective reporting (reporting bias) |
Low risk |
All expected outcomes reported |
