Variable versus conventional lung protective mechanical ventilation during open abdominal surgery (PROVAR): a...

Area of Science:

• Anesthesiology
• Critical Care Medicine
• Respiratory Physiology

Background:

• Previous studies suggested controlled variable ventilation (CVV) benefits injured lungs.
• The hypothesis was that CVV enhances respiratory function during and after open abdominal surgery.

Purpose of the Study:

• To evaluate the efficacy of CVV versus conventional non-variable ventilation (CNV) in improving intraoperative and postoperative respiratory function.
• To assess secondary outcomes including oxygenation, lung volumes, ventilation distribution, and complications.

Main Methods:

• A randomized controlled trial involving 50 patients undergoing open abdominal surgery (>3 hours).
• Patients received either CVV or CNV with standardized tidal volumes and PEEP.
• Primary endpoint: postoperative Day 1 forced vital capacity (FVC); secondary endpoints: oxygenation, lung volumes, and complications.

Main Results:

• No significant difference in postoperative Day 1 FVC between CVV and CNV groups (61.5% vs 61.9%).
• Intraoperative respiratory function, hemodynamics, and ventilation distribution showed no improvement with CVV.
• Postoperative lung function, atelectasis, and inflammatory markers (IL-6, IL-8) did not differ between groups.

Conclusions:

• CVV did not offer significant advantages over CNV in improving intraoperative or postoperative respiratory function in patients undergoing open abdominal surgery.
• The study did not support the hypothesis that CVV improves respiratory outcomes in this patient population.