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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.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| PEEP2 + RM | Experimental | General anesthetic, 40 minutes of Low-tidal volume ventilation with PEEP=2 cmH2O and scheduled recruiting maneuvers at the beginning of each PEEP step, continuous fluid administration at a standard dose, fluid resuscitation or amine administration if deemed necessary by the attending physician blinded to the design of the study |
|
| PEEP7 + RM | Experimental | General anesthetic, 40 minutes of Low-tidal volume ventilation with PEEP=7 cmH2O and scheduled recruiting maneuvers at the beginning of the PEEP step, continuous fluid administration at a standard dose, fluid resuscitation or amine administration if deemed necessary by the attending physician blinded to the design of the study |
|
| PEEP12 + RM | Experimental | General anesthetic, 40 minutes of Low-tidal volume ventilation with PEEP=12 cmH2O and scheduled recruiting maneuvers at the beginning of the PEEP step, continuous fluid administration at a standard dose, fluid resuscitation or amine administration if deemed necessary by the attending physician blinded to the design of the study |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Fluid resuscitation or amine administration | Drug | 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 |
| Measure | Description | Time Frame |
|---|---|---|
| Driving Pressure | Respiratory system elastic pressure (Plateau pressure-total PEEP) | At the end of each 40-minute step |
| Measure | Description | Time Frame |
|---|---|---|
| Lung strain | Lung static and dynamic strain | At the end of each 40-minute step |
| Dead space | Approximated as the difference between End-tidal CO2 and PaCO2 divided by PaCO2 |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| Massimo Antonelli, MD | Catholic University of the Sacred Heart | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| General surgery OR, A. Gemelli hospital | Rome | 00100 | Italy |
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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.
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| PEEP2 - RM | Experimental | General anesthetic, 40 minutes of Low-tidal volume ventilation with PEEP=2 cmH2O, continuous fluid administration at a standard dose, fluid resuscitation or amine administration if deemed necessary by the attending physician blinded to the design of the study |
|
| PEEP7 - RM | Experimental | General anesthetic, 40 minutes of Low-tidal volume ventilation with PEEP=7 cmH2O, continuous fluid administration at a standard dose, fluid resuscitation or amine administration if deemed necessary by the attending physician blinded to the design of the study |
|
| PEEP12 - RM. | Experimental | General anesthetic, 40 minutes of Low-tidal volume ventilation with PEEP=12 cmH2O, continuous fluid administration at a standard dose, fluid resuscitation or amine administration if deemed necessary by the attending physician blinded to the design of the study |
|
| General anesthetic | Drug | Total intravenous anesthesia with a standard protocol |
|
| Fluid administration | Drug | 3-5 ml/kg of balanced crystalloids will be administered throughout the whole surgical procedure |
|
| Low-tidal volume ventilation | Procedure | 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 |
|
| Scheduled recruiting maneuvers | Procedure | 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 |
|
| At the end of each 40-minute step |
| Oxygenation | PaO2/FiO2 | At the end of each 40-minute step |
| Lung recruitment | % (lung recruitment/change in end-expiratory lung volume) | At the end of each 40-minute step |
| Lung overdistension due to PEEP | % (lung overdistension/change in end-expiratory lung volume) | At the end of each 40-minute step |
| Functional residual capacity | Change in functional residual capacity due to PEEP, measured with the Nitrogen washin-washout technique | At the end of each 40-minute step |
| Heart rate | heart rate | At the end of each 40-minute step |
| Blood pressure | Arterial blood pressure | At the end of each 40-minute step |
| Stroke volume | Stroke volume, measured by pulse contour analysis | At the end of each 40-minute step |
| Stroke volume variation | Stroke volume variation, measured by pulse contour analysis | At the end of each 40-minute step |
| Cardiac Output | Stroke volume x heart rate | At the end of each 40-minute step |
| Fluid requirements | Fluid bolus requirements, according to the decision of the attending physician blinded to the design of the study | At the end of each 40-minute step |
| Vasoactive agents | Vasoactive agents requirements, according to the decision of the attending physician blinded to the design of the study | At the end of each 40-minute step |
| Adverse events | Adverse events | At the end of each 40-minute step |
| ID | Term |
|---|---|
| D018681 | Anesthetics, General |
| D055103 | Hypodermoclysis |
| ID | Term |
|---|---|
| D000777 | Anesthetics |
| D002492 | Central Nervous System Depressants |
| D045505 | Physiological Effects of Drugs |
| D020228 | Pharmacologic Actions |
| D020164 | Chemical Actions and Uses |
| D002491 | Central Nervous System Agents |
| D045506 | Therapeutic Uses |
| D055104 | Infusions, Subcutaneous |
| D007263 | Infusions, Parenteral |
| D004333 | Drug Administration Routes |
| D004358 | Drug Therapy |
| D013812 | Therapeutics |
| D005440 | Fluid Therapy |
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