Intraoperative Protective Ventilation in Abdominal Surgery (IMPROVE Study)

Postoperative complications are associated with a significant and quantifiable rate of both morbidity and mortality, increased length of hospital stay and cost of care. Intra-abdominal surgery, especially upper abdominal surgery, is an important risk factor of both pulmonary and extra-pulmonary complications. Up to 15-20% of patients will develop postoperative respiratory failure which may require respiratory support.

Recent data from both experimental and clinical studies suggested that, compared with conventional ventilation using high tidal volume (TV) without positive end-expiratory pressure (PEEP), intraoperative lung protective ventilation using low tidal volume, PEEP and recruitment maneuvers (RM) could reduce postoperative complications. Conventional ventilation promotes sustained cytokine production and could therefore contribute to development of lung injury with in patients with normal lungs. Conversely, lung protective ventilation was found to reduce pulmonary and systemic inflammation.

The primary objective is to compare a lung protective ventilation with conventional ventilation (high tidal volumes without PEEP) during abdominal surgery: 1- Conventional ventilation with TV of 10-12 mL/kg predicted body weight (PBW) without PEEP; 2- Protective lung ventilation with TV of 6-8 mL/kg PBW, PEEP of 6-8 cmH2O and RM.

Our hypothesis is that lung protective ventilation could reduce postoperative pulmonary and extra-pulmonary complications compared with conventional ventilation.

Inclusion criteria

• Planned intrabdominal surgery
• Expected duration ≥ 2 hours
• Age ≥ 40 yr (and <90 yr)
• Risk of postoperative pulmonary complications (Arozullah score ≥2)

Exclusion criteria

• Noninvasive ventilation in the last 30 days
• Recent history of pneumonia, ALI/ARDS (in the last 30 days)
• History of pulmonary resection
• History of neuromuscular disease
• Patient refusal