Anesthesia, General, Surgery
Conditions
Brief summary
Low-tidal volume ventilation is arising as a tool to optimize the ventilatory management and to improve clinical outcome in patients undergoing general anesthesia for abdominal surgery. A recent large randomized controlled trial failed to detect a significant difference between two different approaches for ensuring adequate lung recruitment (PEEP=12 cmH2O + scheduled recruiting maneuvers vs. PEEP 2 cmH2O) during protective ventilation. Thus, in patients undergoing open abdominal surgery and receiving low-tidal volumes, the effects of different positive end-expiratory pressure (PEEP) levels and recruiting maneuvers remain to be established. Design: prospective, cross-over, physiological trial. PURPOSE To assess the physiological effects of different PEEP levels with or without scheduled recruiting maneuvers in patients undergoing general anesthesia for open abdominal surgery and receiving low-tidal volume ventilation.
Interventions
DRUGFluid resuscitation or amine administration
Fluid administration or amine administration if deemed necessary by the attending physician. Haemodynamics will be monitored through noninvasive cardiac output assessment by arterial pulse contour analysis
DRUGGeneral anesthetic
Total intravenous anesthesia with a standard protocol
3-5 ml/kg of balanced crystalloids will be administered throughout the whole surgical procedure
PROCEDURELow-tidal volume ventilation
Volume-control ventilation with tidal volume=7 ml/kg of predicted body weight for the entire surgical procedure. Respiratory rate will be set to maintain EtCO2 within a physiological range and kept unchanged for the entire duration of the study
PROCEDUREScheduled recruiting maneuvers
Pressure-control ventilation inspiratory pressure=10 cmH2O. Steplike 5-cmH2O-PEEP increase every 30 seconds to achieve a peep of 35 cmH2O, followed by 5-cmH2O-PEEP reduction every 30 seconds to set PEEP
Sponsors
Catholic University of the Sacred Heart
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
TREATMENT
Masking
SINGLE (Subject)
Intervention model description
Each patient will be randomized to receive or not scheduled recruiting maneuvers every hour. In each of the two groups, patients will receive mechanical ventilation with 3 different levels of PEEP in a sequential, randomized, cross-over manner: each period will last 40 minutes. A randomization sequence will be produced by a dedicated software and sealed envelopes will be used to allocate patients to study treatments.
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* ASA physical status I-II patients * scheduled for open abdominal surgery (major gastrointestinal surgery: duodeno-cephalo-pancreatectomy, gastrectomy, hemi-colectomy; gynecological surgery; oncologic surgery) * Expected duration of surgery \>= 150 minutes
Exclusion criteria
* Pregnancy * BMI\>30 kg/m\^2 * hepatic surgery * Cardiac failure NYHA\>2 * History of chronic respiratory failure
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Driving Pressure | At the end of each 40-minute step | Respiratory system elastic pressure (Plateau pressure-total PEEP) |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Dead space | At the end of each 40-minute step | Approximated as the difference between End-tidal CO2 and PaCO2 divided by PaCO2 |
| Oxygenation | At the end of each 40-minute step | PaO2/FiO2 |
| Lung recruitment | At the end of each 40-minute step | % (lung recruitment/change in end-expiratory lung volume) |
| Lung overdistension due to PEEP | At the end of each 40-minute step | % (lung overdistension/change in end-expiratory lung volume) |
| Functional residual capacity | At the end of each 40-minute step | Change in functional residual capacity due to PEEP, measured with the Nitrogen washin-washout technique |
| Heart rate | At the end of each 40-minute step | heart rate |
| Lung strain | At the end of each 40-minute step | Lung static and dynamic strain |
| Stroke volume | At the end of each 40-minute step | Stroke volume, measured by pulse contour analysis |
| Stroke volume variation | At the end of each 40-minute step | Stroke volume variation, measured by pulse contour analysis |
| Cardiac Output | At the end of each 40-minute step | Stroke volume x heart rate |
| Fluid requirements | At the end of each 40-minute step | Fluid bolus requirements, according to the decision of the attending physician blinded to the design of the study |
| Vasoactive agents | At the end of each 40-minute step | Vasoactive agents requirements, according to the decision of the attending physician blinded to the design of the study |
| Adverse events | At the end of each 40-minute step | Adverse events |
| Blood pressure | At the end of each 40-minute step | Arterial blood pressure |
Countries
Italy
Outcome results
None listed