Mechanical Power for Ventilatory Settings in Operating Room (IMPROVEIII)

Mechanical Power for Ventilatory Settings in Operating Room: a Multicenter Randomized Controlled Trial

Postoperative respiratory failure (PRF) is a dreaded complication that imposes a significant burden through unplanned admission to the ICU, post discharge disability and mortality. Despite widespread implementation of intraoperative lung-protective ventilation strategies over the past decade, results remain inconsistent. Interventions targeting individual parameters like tidal volume or positive end-expiratory pressure (PEEP) have shown equivocal results. The use of high PEEP and recruitment maneuvers raises safety concerns by possible negative hemodynamic effects. Recent studies suggest that individualizing ventilation strategies based on mechanical power-a composite parameter integrating tidal volume, plateau pressure, PEEP, and ventilator frequency-may better predict and help prevent PRF, independently of patients' baseline respiratory system compliance. These studies identified this parameter as interventional targets to reduce lung injury during mechanical ventilation. However, no multicenter randomized controlled trial has been performed in the field of ventilatory settings titration during invasive mechanical ventilation in operating room.

The investigators hypothesize that a ventilation strategy aimed at decreasing mechanical power will reduce the incidence of PRF and mortality in patients undergoing abdominal surgery, compared with a standard strategy using fixed tidal volume and PEEP

Study Overview

• Status: Not yet recruiting
• Conditions: Abdominal Surgery; Morality; Postoperative Pulmonary Complications; Postoperative Respiratory Failure
• Intervention / Treatment: Procedure: Mechanical power-guided ventilatory strategy; Procedure: Standard fixed ventilatory settings

Detailed Description

Postoperative respiratory failure (PRF) is a dreaded complication that imposes a significant burden through unplanned admission to the intensive care unit (ICU) and post discharge disability. Respiratory failure evident by tracheal intubations 1 month following nonemergent, noncardiac surgeries has been associated with a nine-fold increase in mortality. Efforts to reduce the rates of PRF have incorporated intraoperative ventilation strategies as a central element, with lung-protective ventilation following recommendations for the ICU setting being broadly implemented over the past decade. Interventions targeting individual parameters like tidal volume have shown equivocal results. To summarize, two randomized clinical trials showed lung-protective ventilation with low tidal volume (VT) in addition to high positive end-expiratory pressure (PEEP) and recruitment maneuver (RM) to prevent against postoperative pulmonary complications when compared with ventilation with high VT plus low PEEP without RM. Two other large, randomized trials found no benefit of high PEEP with RM compared with low PEEP without RM in this setting, suggesting that beneficial effects arise primarily from the use of low VT ventilation. Concerns have also been raised about possible negative hemodynamic effects of high PEEP and RMs in these studies. One size does not fit all. Individualized strategies are needed, such as ones using driving pressure (plateau pressure - PEEP), to perform PEEP titration. Using this calculated parameter, reduced incidence of postoperative pulmonary complications has been demonstrated in small randomized controlled trials, and not achieved in others. However, tidal volume and respiratory rate are also important parameters to limit ventilator induced injuries, and are not considered when assessing driving pressure. Mechanical power, a concept that in addition to tidal volume, plateau pressure and positive end-expiratory pressure (PEEP) also integrates the ventilatory frequency, has been recently associated with a higher risk of PRF. This formula is now implemented in the most recent operating room ventilators, and used in routine by some teams, with lack of evidence showing an efficacy of this strategy to set ventilatory settings. Although it has become clear that high mechanical power identifies patients at risk of PRF both in the operating room and ICU, there is an ongoing debate about whether they are linked to PRF, or whether these parameters merely represent an epiphenomenon in patients with impaired respiratory system mechanics and elevated risk at baseline.

Recently, several studies showed that high mechanical power was associated with PRF independent from patients' baseline respiratory system compliance. These studies identified this parameter as interventional targets to reduce lung injury during mechanical ventilation. However, no multicenter randomized controlled trial has been performed in the field of ventilatory settings titration during invasive mechanical ventilation in operating room.

The investigators made the hypothesis that a strategy aimed at decreasing mechanical power (tidal volume, respiratory rate and PEEP individually titrated to minimize the mechanical power) will reduce PRF and mortality in patients undergoing abdominal surgery, when compared with that of a strategy of standard care (with fixed level of tidal volume and PEEP). The investigators expect decreased PRF and mortality rate in the group "mechanical power-guided ventilatory settings". The investigators also expect in this group reduced duration of postoperative mechanical ventilation, reduced incidence of postoperative organ dysfunction, and reduced duration of hospital stay.

• Study Type: Interventional
• Enrollment (Estimated): 490
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Audrey DE JONG, Pr; Phone Number: 04 67 33 72 71; Email: a-de_jong@chu-montpellier.fr
• Study Contact Backup: Name: Samir JABER, Pr; Phone Number: 04 67 33 72 71; Email: s-jaber@chu-montpellier.fr

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Adult (≥ 18 years)
• Laparoscopic or non-laparoscopic abdominal surgery
• With an expected duration of at least 2 hours

Exclusion Criteria:

• Patients already receiving mechanical ventilation > 12 hours before surgery;
• Chronic respiratory disease requiring oxygen therapy or mechanical ventilation at home;
• Undrained pneumothorax or subcutaneous emphysema;
• Intracranial hypertension;
• Patients for which death is deemed imminent and inevitable or patients with an underlying disease process with a life expectancy of less than 3 months;
• Patients already enrolled in the IMPROVE III trial;
• Pregnancy in progress or planned during the study period or breastfeeding women (Art. L1121-5 of the French Public Health Code);
• Patients protected by law (Art. L1121-6 to L1121-8 of the French Public Health Code): Individuals deprived of their liberty by judicial or administrative decision, vulnerable persons, minors, adults under guardianship or curatorship;
• Patients not covered by a French social security scheme and not benefiting from such a scheme;
• Absence of free and informed oral consent from the patient before inclusion (except in emergency situation where the patient is unable to provide consent), or absence of written informed consent from his/her proxy if present in an emergency situation (except in life-threatening emergency, where inclusion without consent from the patient or his/her proxy is permitted), in which case consent will be obtained as soon as possible after inclusion.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Mechanical power-guided ventilatory strategy; In the intervention group, ventilatory settings will be personalized according to the mechanical power, after the surgical incision (whether laparoscopy or laparotomy), and after the pneumoperitoneum insufflation (for laparoscopy only) or stop of pneumoperitoneum insufflation.	Procedure: Mechanical power-guided ventilatory strategy; Tidal volume 7ml/kg PBW and RR titrated for EtCO2 between 40-50mmHg. See calculated Mechanical power:0,049*tidal volume*RR*driving pressure.; Set PEEP 15cmH2O and perform recruitment maneuver at 30cmH2O for 20s. Decrease PEEP from 15 by steps of 2cmH2O until the lower level of PEEP minimizing mechanical power. Note mechanical power. Stop maneuver and/or decrease level of PEEP if decrease>20% of cardiac output during the maneuver, when compared to baseline.; Repeat this step using 9 ml/kg PBW and choose the optimal tidal volume with lowest mechanical power. During the surgery, adjust RR to maintain EtCO2 between 40-50mmHg, with an inspiratory-to-expiratory time ratio of 1:2 to 1:1, an end-inspiratory pause of 30%, an FiO2 adjusted to maintain SpO2≥94%. Recruitment maneuvers will be performed after intubation, in case of ventilator disconnection, coelioscopy insufflation, change of position, at the end of surgery, or if mechanical power >30%.
Active Comparator: Control group with standard fixed ventilatory settings; In the control group, standard care will be performed.	Procedure: Standard fixed ventilatory settings; Tidal volume 7 ml/kg predicted body weight, calculated according to a predefined formula: 50+0.91 x (centimeters of height - 152.4) for males and 45.5+0.91 x (centimeters of height - 152.4) for females, fixed PEEP between 6 and 8 cmH20, recruitment maneuvers at the discretion of the physician. The respiratory rate will be adjusted to maintain end-tidal partial pressure of CO2 between 30 and 40 mmHg, a target reported to be used by approximately 90% of physicians according to a recent online survey administered to French anesthesiologists via the French Society of Anesthesia & Intensive Care Medecine (SFAR), which will be published soon, with an inspiratory-to-expiratory time ratio of 1:2 to 1:1, an end-inspiratory pause of 30 %, and an FiO2 adjusted to maintain SpO2 ≥ 94%. Mechanical power will not be measured during the surgery to avoid any modification of the ventilatory setting by the physician in charge.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Composite of postoperative respiratory failure	Defined as failure to wean from the ventilator within the first 12 hours after surgery	Up to 12 hours after surgery
Composite of postoperative respiratory failure	Defined as the need for unplanned reintubation following the end of surgery, once extubated	Up to 30 days after surgery, or by the date of hospital discharge, if this occurs before Day 30
Composite of postoperative respiratory failure	Defined as the need for therapeutic non-invasive ventilation following the end of surgery, once extubated	Up to 30 days after surgery, or by the date of hospital discharge, if this occurs before Day 30
All-cause mortality	Defined as death from any cause occurring within 30 days following surgery. The time to death will be measured from the date of surgery to the date of death. Patients discharged from hospital alive before Day 30 or still alive at Day 30 will be considered censored at that time.	Up to 30 days after surgery, or by the date of hospital discharge, if this occurs before Day 30

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Severity of postoperative pulmonary complications following surgery	The severity of pulmonary complications after surgery will be scored on a grade scale ranging from 0 to 4, with grade 0 representing the absence of any pulmonary complication and grades 1 through 4 representing successively the worse forms of pulmonary complications	Up to 30 days after surgery, or by the date of hospital discharge, if this occurs before Day 30
Renal dysfunction following surgery	Postoperative renal dysfunction will be assessed using the Kidney Disease: Improving Global Outcomes (KDIGO) Acute Kidney Injury Classification, based on serum creatinine levels and urine output criteria. The KDIGO classification ranges from Stage 0 to Stage 3, where higher stages indicate more severe renal dysfunction (Stage 0 = no acute kidney injury; Stage 3 = most severe acute kidney injury). Renal dysfunction will be defined as KDIGO Stage 1 or higher.	Up to 30 days after surgery, or by the date of hospital discharge, if this occurs before Day 30
Sepsis and septic shock following surgery	Will be evaluated after surgery, according to the last recommendations on sepsis and septic shock	Up to 30 days after surgery, or by the date of hospital discharge, if this occurs before Day 30
Sepsis-related Organ Failure Assessment (SOFA)	The SOFA score will be collected at randomization, at Day 1, at Day 7 to evaluate the extent of organ dysfunction. The score includes six organ systems: respiratory, cardiovascular, hepatic, coagulation, renal, and neurological function. Each system is graded from 0 (normal function) to 4 (severe dysfunction) based on objective clinical or laboratory parameters. The Glasgow Coma Score will be excluded from the calculation	At randomization (day 0), at Day 1, at Day 7
Ventilator-free days (VFDs)	A ventilator-free day is defined as the receipt as < 2 hours of invasive mechanical ventilation or non-invasive mechanical ventilation (as curative therapy) within a 24-hour period	Up to 30 days after surgery, or by the date of hospital discharge, if this occurs before Day 30
Duration of invasive mechanical ventilation	Measured from the time of initiation of mechanical ventilation to the first tracheal extubation	Up to 30 days after surgery, or by the date of hospital discharge, if this occurs before Day 30
Total duration of mechanical ventilation	Total duration of invasive mechanical ventilation will be measured in days from the initiation of mechanical ventilation until final discontinuation during the follow-up period. All periods of invasive mechanical ventilation, including episodes requiring reintubation, will be included in the total duration calculation.	Up to 30 days after surgery, or by the date of hospital discharge, if this occurs before Day 30
Time to successful tracheal extubation	Successful extubation reflects both effective weaning from mechanical ventilation and the patient's ability to maintain adequate spontaneous breathing. it's defined as the interval from the time of initiation of mechanical ventilation to the tracheal extubation that is not followed by reintubation within 7 days	Up to 30 days after surgery, or by the date of hospital discharge, if this occurs before Day 30
ICU-free days	Are defined as the number of days a patient is both alive and discharged from the intensive care unit (ICU) during the first 30 days following surgery. Patients who die before ICU discharge will be assigned zero ICU-free days. The outcome will be censored at 30 days postoperatively or at the time of hospital discharge, whichever occurs first	Up to 30 days after surgery, or by the date of hospital discharge, if this occurs before Day 30
Length of ICU stay	Will be measured from the date of ICU admission to the date of discharge from the ICU. Patients who are still in ICU on day 30 will be considered censored at that time	Up to 30 days after surgery, or by the date of hospital discharge, if this occurs before Day 30
Length of hospital stay	Will be measured from the date of hospital admission to the date of discharge from the hospital. Patients who are transferred to another type of healthcare facility (e.g., rehabilitation center) before Day 30 will be considered as having been discharged from the hospital. Patients who are still in hospital on day 30 will be considered censored at that time	Up to 30 days after surgery, or by the date of hospital discharge, if this occurs before Day 30
Time to death (or censoring)	Is defined as the time from the date of surgery to the occurrence of death. Data will be collected up to Day 30, or until the date of hospital discharge, if this occurs before Day 30. Patients who do not die during this period will be considered censored at that time	Up to 30 days after surgery, or by the date of hospital discharge, if this occurs before Day 30

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postoperative hypoxemia	Defined as a PaO₂/FiO₂ ratio ≤ 300 mmHg measured by arterial blood gas analysis performed within 1 hour after extubation, indicating early hypoxemic respiratory failure following surgery	Up to 30 days after surgery, or by the date of hospital discharge, if this occurs before Day 30
Postoperative pneumonia	Defined as a new or progressive pulmonary infiltrate on chest imaging combined with at least one clinical sign (fever, abnormal white blood cell count, purulent secretions, or positive respiratory culture), occurring after surgery, according the European Perioperative Clinical Outcome (EPCO) criteria	Up to 30 days after surgery, or by the date of hospital discharge, if this occurs before Day 30
Acute Respiratory Distress Syndrome (ARDS)	Defined as acute hypoxemic respiratory failure with bilateral pulmonary opacities not fully explained by cardiac failure or fluid overload, and a PaO₂/FiO₂ ratio ≤ 300 mmHg with PEEP ≥ 5 cmH₂O, under invasive or non-invasive ventilation	Up to 30 days after surgery, or by the date of hospital discharge, if this occurs before Day 30
Total intraoperative intravenous fluid volume	The total volume of crystalloids and colloids (millilitres) during surgery will be recorded	During surgery
Total Intraoperative vasopressor dose	The total dose of norepinephrine, epinephrine, phenylephrine, ephedrine during surgery will be recorded.	During surgery
Mechanical power	Mechanical power during surgery will be reported in joules/minute (J/min). If not directly provided by the anesthesia ventilator, it will be calculated using a predefined formula based on recorded ventilatory parameters (tidal volume (ml/kg PBW), respiratory rate, Ppeak (cm H2O), Pplat (cm H2O), PEEP (cm H2O)).	During surgery
Tidal volume normalized to predicted body weight	Tidal volume normalized to predicted body weight will be recorded in mL/kg PBW during surgery for the calculation of mechanical power.	During surgery
Respiratory rate	Respiratory rate will be recorded in breaths per minute during surgery for the calculation of mechanical power.	During surgery
Peak inspiratory pressure (Ppeak)	Peak inspiratory pressure will be recorded in cm H2O during surgery for the calculation of mechanical power.	During surgery
Plateau pressure (Pplat)	Plateau pressure will be recorded in cm H2O during surgery for the calculation of mechanical power.	During surgery
Positive end-expiratory pressure (PEEP)	Positive end-expiratory pressure will be recorded in cm H2O during surgery for the calculation of mechanical power.	During surgery
Ventilation-related adverse events	Including presence of hemodynamic instability, pneumothorax and any other life-threatening reason for which the clinician would decide to stop the intervention.	Up to 30 days after surgery, or by the date of hospital discharge, if this occurs before Day 30
Rescue therapy for intraoperative hypoxemia	Defined as implementation of any therapy aiming to correct intraoperative hypoxemia such as recruitment maneuvers, a stepwise increase in FiO₂, or increase of the level of PEEP not following the initial recommendations for each group.	During surgery

Collaborators and Investigators

• Sponsor: University Hospital, Montpellier
• Investigators: Principal Investigator: Audrey DEBRUS, Dr, University Hospital, Montpellier

Study record dates

Study Major Dates

• Study Start (Estimated): June 1, 2026
• Primary Completion (Estimated): January 1, 2029
• Study Completion (Estimated): January 1, 2029

Study Registration Dates

• First Submitted: May 15, 2026
• First Submitted That Met QC Criteria: May 26, 2026
• First Posted (Actual): June 2, 2026

Study Record Updates

• Last Update Posted (Actual): June 2, 2026
• Last Update Submitted That Met QC Criteria: May 26, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Intensive care unit; Intubation; Mechanical ventilation; Mechanical power-guided ventilation; Laparoscopic or non-laparoscopic abdominal surgery
• Other Study ID Numbers: RECHMPL24_0492

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No