Laparoscopy
Conditions
Brief summary
The effect of driving pressure (DP)-guided positive end expiratory pressure (PEEP) on early postoperative pulmonary ventilation is to be determined for patients undergoing laparoscopic surgery. Patients are recruited to receive volume controlled ventilation with either a fixed PEEP (5cmH2O) or DP titrated PEEP. Early postoperative regional distribution of lung ventilation, expressed as center of ventilation (COV) is evaluated by electrical impedance tomography (EIT), a noninvasive, radiation free modality. Perioperative ventilatory parameters, arterial oxygenation index (PaO2/FiO2) , serum indicators and postoperative pulmonary complications are secondary outcome variables.
Detailed description
After screened for preoperative risk factors, 48 patients undergoing elective laparoscopic surgery and planned to be extubated in the operating room are randomly assigned to two groups: (1) PEEP = 5cmH2O; (2) driving pressure (DP)-guided PEEP. The ventilation protocol consists of volume-controlled mechanical ventilation (Datex Ohmeda S/5 Advance; General Electric Company Healthcare, Helsinki, Finland) at a tidal volume (VT) of 8 ml/kg predicted body weight (PBW), fresh gas of 2 litre /min, inspiratory to expiratory ratio of 1:2, and a respiratory rate adjusted to normocapnia (arterial carbon dioxide partial pressure between 35 and 45 mmHg). For group 2, trial for the lowest DP was started 10 min after pneumoperitoneum and position adjustment by increasing PEEP from 5 to 15 cm H2O incrementally. DP was calculated as plateau pressure - PEEP. Each PEEP level was maintained for 10 respiratory cycles, with DP in the last cycle recorded. Then the PEEP level producing the lowest DP was identified and maintained intraoperatively. A plateau pressure of no more than 30 cmH2O is targeted in each group. Early postoperative distribution of regional ventilation as COV (center of ventilation) is the primary endpoint evaluated by EIT (electrical impedance tomography), which was performed by a trained technician who is blinded to randomization. Arterial blood gas is tested, with inflammatory and oxidative mediators from venous sample. Postoperative pulmonary complications within 3 days are also recorded.
Interventions
PROCEDUREPEEP
different PEEP set on the anesthetic machine
Sponsors
Capital Medical University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
DOUBLE (Subject, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
18 Years to 80 Years
Healthy volunteers
No
Inclusion criteria
* Informed consent has been obtained * Elective laparoscopic surgery with Trendelenburg position * Expected ventilation duration \> 2 hours * Scheduled to be extubated in the operation
Exclusion criteria
* Mechanical ventilation of \> 1 hour within the last 2 weeks before surgery * Body mass index ≥ 35 kg/m2 * Acute respiratory failure (pneumonia, acute lung injury or acute respiratory distress syndrome) * Emergency surgery * Severe cardiac disease * Progressive neuromuscular illness * Pregnancy * Refusal to participate * Contradicted to EIT scan
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| early postoperative overall spatial distribution of pulmonary ventilation | immediately after extubation | global inhomogeneity index (GI): overall degree of spatial heterogeneity of ventilation. GI is measured by electrical impedance tomography (EIT). A smaller GI index represents a more homogeneous distribution, and a larger GI index indicates a more inhomogeneous ventilation. |
Other
| Measure | Time frame | Description |
|---|---|---|
| incidence of postoperative pulmonary complications (PPCs) | within the first 3 days after surgery | Melbourne Group Scale version 2 (MGS-2): Temperature \>38°C; White cell count \>11.2 or use of respiratory antibiotics; Physician diagnosis of pneumonia or chest infection; Chest X-ray findings of atelectasis/consolidation; Production of purulent (yellow/green) sputum different from preoperative sputum; Positive results upon sputum microbiological analysis; oxygen saturation by pulse oximetry （SpO2）\<90% in ambient air; Re-admission to or prolonged stay (\>36 h) in the intensive care unit/high dependency unit for respiratory problems. A PPC was diagnosed if 4 or more of the 8 factors were present. |
Countries
China
Outcome results
None listed