# Intraoperative Ventilation Risk Factors for Postoperative Pulmonary Complications in Patients Undergoing Elective Neoplastic Esophagectomy: A Retrospective Cohort Study

Cédric Cirenei, Raphaëlle Lefebvre, Damien Rousseleau, Emeline Cailliau, Julien Labreuche, Mouhamed Djahoum Moussa, Alexandre Bourgeois, Julie Veziant, Benoit Tavernier, Gilles Lebuffe, et al.

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Cédric Cirenei, Raphaëlle Lefebvre, Damien Rousseleau, Emeline Cailliau, Julien Labreuche, et al. Intraoperative Ventilation Risk Factors for Postoperative Pulmonary Complications in Patients Undergoing Elective Neoplastic Esophagectomy: A Retrospective Cohort Study. Anaesthesia Critical Care & Pain Medicine, 2026, 10.1016/j.accpm.2026.101774. hal-05533721

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Journal Pre-proof

Intraoperative Ventilation Risk Factors for Postoperative Pulmonary
Complications in Patients Undergoing Elective Neoplastic
Esophagectomy: A Retrospective Cohort Study

Cédric Cirenei, Raphaëlle Lefebvre, Damien Rousseleau, Emeline
Cailliau, Julien Labreuche, Mouhamed Djahoum Moussa, Alexandre
Bourgeois, Julie Veziant, Benoit Tavernier, Gilles Lebuffe, Eric Kipnis

<figure><img src="image_2.png" /></figure>

PII: S2352-5568(26)00032-9

DOI: https://doi.org/10.1016/j.accpm.2026.101774

Reference: ACCPM 101774

To appear in: *Anaesthesia Critical Care & Pain Medicine*

Accepted Date: 25 December 2025

Please cite this article as: Cirenei C, Lefebvre R, Rousseleau D, Cailliau E, Labreuche J,
Moussa MD, Bourgeois A, Veziant J, Tavernier B, Lebuffe G, Kipnis E, Intraoperative
Ventilation Risk Factors for Postoperative Pulmonary Complications in Patients Undergoing
Elective Neoplastic Esophagectomy: A Retrospective Cohort Study, *Anaesthesia Critical Care
and Pain Medicine* (2026), doi: https://doi.org/10.1016/j.accpm.2026.101774

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© 2026 Published by Elsevier Masson SAS on behalf of Société française d’anesthésie et de réanimation (SFAR).
# Intraoperative Ventilation Risk Factors for Postoperative Pulmonary Complications in Patients Undergoing Elective Neoplastic Esophagectomy: A Retrospective Cohort Study

Running Head: One-lung and Two-lung intraoperative ventilation and postoperative pulmonary complications

Cédric Cirenei¹,², M.D., MPH; Raphaëlle Lefebvre¹, M.D.; Damien Rousseleau¹,³, M.D.; Emeline Cailliau⁴, BST; Julien Labreuche²,⁴, BST; Mouhamed Djahoum Moussa¹,², M.D., PhD; Alexandre Bourgeois¹,², MD; Julie Veziant, M.D., PhD⁵,⁶; Benoit Tavernier¹,², M.D., PhD; Gilles Lebuffe¹,³, M.D., PhD; Eric Kipnis¹,⁷, M.D.; PhD.

## Affiliations:

¹ CHU Lille, Department of Anesthesiology, Critical Care and Perioperative medicine, F-59000, Lille, France

² Univ. Lille, CHU Lille, ULR 2694 - METRICS : Evaluation des Technologies de santé et des Pratiques médicales, F-59000, Lille, France

³ Univ. Lille, CHU Lille, ULR 7365 - GRITA - Groupe de Recherche sur les formes Injectables et les Technologies Associées, F-59000 Lille, France

⁴ Lille University Hospital, Biostatistics Department, F-59000 Lille, France

⁵ Lille University Hospital, Department of Digestive and Oncological Surgery, Lille University Hospital, F-59000, Lille, France

⁶ UMR-S 1172-CANTHER Laboratory “Cancer Heterogeneity, Plasticity and Resistance to Therapies”, University Lille, 59045 Lille, France

⁷ Univ. Lille, CNRS, Inserm, Lille University Hospital, Institut Pasteur de Lille, U109 – UMR 9017 – CIIL – Center for Infection and Immunity of Lille, F-59000, Lille, France

**Correspondence to:** Dr. Cédric Cirenei, CHU Lille, Department of Anesthesiology and Critical Care, F-59000, Lille, France. cedric.cirenei@chu-lille.fr, ORCID: 0000-0002-8498-8823

## Graphical Abstract
Intraoperative Ventilation Predictors of Postoperative Pulmonary Complications
in Patients Undergoing Elective Neoplastic Esophagectomy: a Retrospective
Cohort Study

<figure><img src="image_3.png" /></figure>

Highlights

* Postoperative pulmonary complications are a major complication after elective neoplastic esophagectomy.

* Plateau pressure, respiratory rate, and driving pressure were independently associated with postoperative pulmonary complications during both one- and two-lung ventilation phases

* During two-lung ventilation, longer duration increases the risk of postoperative pulmonary complications, whereas higher PEEP is protective of PPCs.

* During one-lung ventilation, higher tidal volume and mechanical power are risk factors for postoperative pulmonary complications.

* Intraoperative ventilatory parameters may be modifiable targets to reduce pulmonary morbidity after elective neoplastic esophagectomy.

Abstract

**Background:** Postoperative pulmonary complications (PPCs) are frequent and serious complications after esophagectomy. Our aim was to determine intraoperative ventilatory parameters that are independently associated with PPCs during one-lung ventilation (OLV) and two-lung ventilation (TLV) phases.

**Methods:** This retrospective single-center cohort study included 454 patients undergoing elective esophagectomy with combined abdominal and thoracic approaches. The primary outcome was the
occurrence of PPCs within seven postoperative days. Separate predictive models were established for
OLV and TLV using multivariable logistic regressions with ventilatory parameters.

**Results:** PPCs occurred in 194 patients (42.7%). Plateau pressure (Pplat) and driving pressure (DP) were independently associated with PPCs during both phases (Pplat: OR= 1.73, 95%CI: 1.25-2.38, *p* < 0.001 in OLV; OR = 1.38, 95%CI: 1.00-1.92, *p* = 0.05 in TLV; DP: OR = 1.17, 95%CI: 1.05-1.30, *p* = 0.005 in OLV; OR = 1.14, 95%CI: 1.06-1.23, *p* < 0.001 in TLV). Respiratory rate (RR) was also associated (OR up to 1.62). In TLV, duration of ventilation (OR between 1.39 and 1.41) was associated with PPCs, while positive end-expiratory pressure (PEEP) was protective (OR 0.73). In OLV only, higher tidal volume (VTe) (OR 1.31, 95%CI: 1.303, 1.66, *p* = 0.02) and mechanical power (MP) (OR = 1.29, 95%CI: 1.00-1.64, *p* = 0.05) were associated with PPCs. Model discrimination was acceptable (AUC 0.70–0.76).

**Conclusions:** Pplat, RR, and DP were associated with PPCs in both ventilation phases. During TLV, duration increased and PEEP decreased PPC risk, whereas during OLV, VTe and MP were associated with PPCs.

**Keywords:** Driving pressure, one-lung ventilation, esophagectomy, postoperative pulmonary complications, mechanical power.

**Abbreviations :**

COPD: Chronic Obstructive Pulmonary Disease

Crs: Dynamic Respiratory system Compliance

DP: Driving Pressure

ECOG-PS: Eastern Cooperative Oncology Group – Performance Status

EPCO: European Perioperative Clinical Outcome

EtCO₂: End-tidal Carbon Dioxide

FEV1: Forced Expiratory Volume in One Second

FiO₂: Inspired Fraction of Oxygen

HMIE: Hybrid Minimally-Invasive Esophagectomy

IQR: Inter Quartile Range

MP: Mechanical Power

PEEP: Positive End-Expiratory Pressure

PPC: Postoperative Pulmonary Complications

Ppeak: Peak Pressure

Pplat: Plateau Pressure

OLV: One-Lung Ventilation
RR: Respiratory Rate

SD: Standard Deviation

SpO₂: Pulsed oximetry

TMIE: Totally Minimally-Invasive Esophagectomy

TLV: Two-Lung Ventilation

VTe: End-tidal Volume

INTRODUCTION

Over 300 million surgery procedures are performed each year worldwide [1]. Postoperative pulmonary complications (PPCs) are the second most common after surgical site infections, with an incidence between 5 and 33% [2–5]. Following esophagectomy, PPCs are the leading postoperative complications in up to 28% of cases [6].

Intraoperative mechanical ventilation is known to be associated with PPCs [7–9]. As a result, expert consensus recommends implementing protective ventilation in the operating room [10]. Protective ventilation during surgery in patients without pre-existing pulmonary conditions has been shown to reduce postoperative morbidity and mortality, particularly by lowering the incidence of PPCs [8,11,12]. This approach includes an expiratory tidal volume (VTe) of 6-8 mL.kg⁻¹ of predicted body weight (PBW), the use of “optimal” positive end-expiratory pressure (PEEP), and the use of alveolar recruitment maneuvers. The “optimal” PEEP recommended in the above-mentioned consensus is the PEEP level achieving the highest compliance by preventing alveolar re-collapse while avoiding overdistension. To this end, driving pressure (DP) is defined as plateau pressure minus positive end-expiratory pressure (Pplat-PEEP), taking into account PEEP, compliance (dynamic respiratory system compliance, Crs). DP does not differentiate between variations in pulmonary or extrapulmonary compliance components (atelectasis/overdistension, intrabdominal pressure, or chest wall compliance variations due to surgery). Accordingly, driving pressure is more strongly associated with the occurrence of PPCs than any other ventilatory parameter [13].

Patients undergoing thoracic surgery for lung resection are at risk of PPCs because of underlying disease and the surgical reduction of lung parenchyma. Despite the application of “lung protective ventilation”, the incidence of PPCs remains high in this surgery [14–16]. Unlike data from critical care or major abdominal surgery [13,17], findings on the use and monitoring of driving pressure to reduce PPCs remain contradictory. Some studies suggest a reduction in PPCs with driving pressure-guided ventilation [18], while others fail to demonstrate any benefits [19]. Furthermore, these studies concern only thoracic surgery for lung resection.

The particularities of esophageal surgery are that it may involve both abdominal and thoracic approaches and does not involve lung resection. Consequently, this surgery is longer in duration and has
a higher incidence of PPCs [20,21]. To our knowledge, only limited-size retrospective or prospective clinical studies have specifically focused on one-lung ventilation in the setting of esophageal surgery, and none have investigated the impact of ventilatory parameters during one-lung ventilation.

We hypothesized that intraoperative ventilation plays a pivotal role in the development of PPCs after esophagectomy. Our objective was therefore to identify the most predictive models of the risk of PPCs for the one-lung ventilation (OLV) and two-lung ventilation (TLV) phases of esophagectomy, and determine the ventilatory parameters that contributed most to this risk.

# MATERIALS AND METHODS

## Study Design

We conducted a retrospective single-center observational study including 454 consecutive elective esophagectomies performed between March 2018 and May 2023 at Lille University Hospital, France. The study was approved by the Research Ethics Committee of the French Society of Anaesthesia and Intensive Care (CERAR IRB 00010254-2023-091, November 30, 2023), which waived the need for written consent from the patient. In compliance with French regulations, patients received written information on the use of their data in this research and were provided with a recourse to oppose the use of their data at any time. The study followed the STROBE guidelines.

## Population

Adults (≥18 years) undergoing elective esophagectomy for esophageal or esophagogastric junction cancer via combined thoracic and abdominal approaches were included. The Ivor-Lewis and McKeown techniques were both used. Emergency cases were excluded.

## Objectives

The primary objective was to analyze ventilatory parameters during each phase of ventilation (OLV and TLV) on the occurrence of PPCs and to establish a predictive model.

## Exposures

Standard anesthesia included epidural analgesia, sufentanil, propofol, and a neuromuscular blocking agent. Orotracheal intubation was achieved using a double-lumen tube (Rüsch®, Teleflex, Ireland). OLV was used during the thoracic phase. Volume-controlled ventilation was delivered via ventilators connected to the anesthesia information system. Ventilatory parameters were automatically recorded every 30 seconds. Drug administration and recruitment maneuvers were recorded manually into the anesthesia information management system by the attending anesthesiologist.

Patients were exposed to mechanical ventilation during surgery, with VTe, RR, and PEEP settings determined by the attending anesthesiologist. In the department, ventilator settings are
protocolized within ranges as follows: during TLV the VTe is set between 6 and 8 mL.kg⁻¹ of PBW, with a minimum PEEP of 5 cmH₂O, which can go up to 10 cmH₂O, and a RR set to maintain an End-tidal Carbon dioxide (EtCO₂) between 35 and 45 mmHg, an inspired fraction of oxygen (FiO₂) set for peripherical oxyhaemoglobin (SpO₂) above 95%. During OLV, the VTe is set between 4 and 6 mL.kg⁻¹ of PBW, with a minimum PEEP of 5 cmH₂O and a RR to achieve an EtCO₂ between 35 and 45 mmHg. Pplat, inspiratory peak pressure (Ppeak), and DP resulted from these settings and the patient lung mechanical properties. No intervention was systematically performed for the non-dependent lung during OLV; oxygen insufflation or continuous positive airway pressure (CPAP) on the non-dependent lung was neither protocolized nor collected. Ventilatory parameters (Pplat, driving pressure, mechanical power, PEEP, etc.) were averaged arithmetically over each ventilation phase (OLV and TLV). As the monitoring system records data at fixed intervals, these averages are equivalent to time-weighted means.

Mechanical power (MP), which integrates ventilatory parameters derived from both ventilator settings and the mechanical properties of the patients' lungs, was calculated retrospectively offline as previously described [22]:

MP is defined as follows:

$$MP (J.min^{-1}) = 0.098 \times RR \times VTe \times 0.001 \times (PEEP + 0.5 \times (Pplat - PEEP) \times (Ppeak - PEEP)).$$

In our study, MP refers to average MP, where each variable is averaged over a defined timeframe, i.e.: OLV or TLV procedure ventilation.

## Outcomes

The primary outcome was the occurrence of at least one PPC within the first 7 postoperative days. PPCs were defined according to the European Perioperative Clinical Outcome definitions (EPCO)[23] (see Supplemental material eTable 1). PPCs were retrospectively studied as a composite outcome of the occurrence of at least one of the following pulmonary complications: acute respiratory failure, atelectasis, pneumonia, aspiration pneumonia, pleural effusion, pneumothorax, and acute respiratory distress syndrome.

## Data Collection

Demographic data, medical history, comorbidities (respiratory, cardiovascular, alcohol and smoking, diabetes, Eastern Cooperative Oncology Group – Performance Status (ECOG-PS), and cancer characteristics were collected from the electronic medical records. Surgical approaches were categorized as: open esophagectomy (laparotomy and thoracotomy), hybrid minimally-invasive esophagectomy (HMIE) (laparotomy and thoracoscopy or laparoscopy and thoracoscopy), or totally mini-invasive esophagectomy (TMIE) (laparoscopy and thoracoscopy). Perioperative ventilatory parameters were
recorded using the Diane® anesthesia information software (BowMedical, Amiens, France), and postoperative data were collected through the Sillage® electronic health record software (SIB, Rennes, France). Ventilatory data were automatically extracted from the Lille University Hospital data warehouse [24].

## Confounding Factors

Predefined confounders based on the literature and those deemed relevant for three experts in the context included age, ASA score, BMI, diabetes, smoking, forced expiratory volume in one second (FEV1), $FiO_2$, $SpO_2$, intraoperative transfusion, fluid loading, surgical duration, and surgical approach[25–28].

## Statistical Analysis

No formal sample size calculation was performed, as the objective was to include all eligible patients to maximize the number of PPC events.

Categorical variables were expressed as counts and percentages, and continuous variables as means ± standard deviation or medians [interquartile range] as appropriate. Normality was assessed graphically and using the Shapiro–Wilk test. Patient characteristics and intraoperative data were described overall and according to PPC occurrence; they were compared according to PPC occurrence using Student's t-test for quantitative variables and Chi-square test for categorical variables; standardized differences (≥20%) with their 95% confidence intervals were used to quantify meaningful contrasts between groups.

A first multivariable logistic regression model of PPCs probability was built by including only predefined confounders; the model discrimination was evaluated using the c-statistic (AUC, 95% CI). Adjusted odds ratios (ORs) for each parameter of interest were reported per one standard deviation increase with 95% confidence intervals as effect sizes. The additional explicative variables (intraoperative ventilatory parameters) were tested sequentially by adding them to the initial model, alone or in combination, according to clinical relevance and multicollinearity. OLV and TLV parameters were analyzed in distinct logistic regression models to prevent intra-patient correlation between each phase of ventilation. Missing data were imputed under the missing-at-random assumption using multiple imputation by chained equations (m = 20) with predictive mean matching for continuous and logistic regression for categorical variables[29]. Estimates were pooled using Rubin's rules[30]. Associations between PPCs and patients' evolution were evaluated using a logistic regression model for Dindo-Clavien score≥3 and endotracheal intubation, and using an analysis of variance (ANOVA) model for lengths of stay (on log-transformed data). Analyses were performed with SAS v9.4 (SAS Institute, Cary, NC) using a two-tailed α of 0.05.
RESULTS

From January 2018 to May 2023, 454 patients underwent elective esophagectomy (Figure 1). Baseline characteristics are summarized in Table 1. Patients were predominantly male (366 or 80.6%), with a mean age of 63.7 ± 9.6 years. Most had an ASA score of 2 (373, 60.1%) and an ECOG-PS of 0 (319, 70.3%). Cancer histology was similar between groups, with adenocarcinomas in 323 patients (71.1%). The most frequent comorbidities were arterial hypertension (204, 44.9%) and chronic obstructive pulmonary disease (COPD) (42, 9.3%); 71 patients (15.6%) were active smokers. Overall, 194 patients (42.7%) experienced PPCs. The main types of PPCs were: pneumonia for 100 patients (51.5%), followed by atelectasis affecting 88 patients (45.3%), and acute respiratory failure affecting 63 patients (31.9%) (eTable 2). Pleural effusions, pneumothorax, and acute respiratory distress syndrome affected 48 (24.7%), 22 (11.3%), and 27 (13.9%) patients, respectively. The median time to PPC diagnosis was on post-operative day 4 (2;6).

The intraoperative data are summarized in Table 2. Ivor-Lewis esophagectomy was the most performed procedure in 435 patients (95.8%). The TMIE approach was the most performed in 289 patients (63.7%). Patients who developed a PPC were more likely to have a history of myocardial infarction, hypertension, COPD, or peripheral vascular disease. They also experienced more bleeding than those who did not.

Description of intraoperative ventilatory parameters is presented in Table 3. There was a difference in mean VTe based on the predicted body weight (5.4 ± 0.7 mL.kg⁻¹ versus 5.2 ± 0.7 mL.kg⁻¹, SD: 25.4%) between the PPCs and the no PPCs groups during OLV. The average driving pressure during OLV was higher in the PPCs group (17.5 ± 4.3 cmH₂O) than in the no PPCs group (15.4 ± 3.4 cmH₂O, SD 54.4%). The average plateau pressure was higher in the PPCs group (24.6 ± 4.3 cmH₂O) than in the no PPCs group (22.5 ± 3.4 cmH₂O, SD: 54.7%). During TLV, driving pressure was higher in the PPCs group versus no PPCs (12.5 ± 2.8 cmH₂O vs. 11.4 ± 2.5 cmH₂O, SD: 42.9%). There was no difference between the average PEEP levels in the two groups in OLV or TLV (SD -1.4% and -7.5% respectively).

Multivariable analysis

Several ventilatory parameters were associated with PPCs across all ventilation phases, according to the models: Pplat (model 1), RR (models 1 and 2), and DP (model 2) (Figure 2). In TLV, and not OLV, duration of ventilation (all models) was associated with PPCs, and PEEP (model 1) was protective. In OLV only, Vte (model 1) and MP (model 3) were associated with PPCs. In a supplementary analysis, considering overall ventilation rather than TLV and OLV separately, findings closely mirrored those of the TLV phase (see Supplemental material, eTable 3 and 4). AUCs were comparable between all models (Figure 2).
## Secondary analysis

Patients who experienced PPCs were more likely to be reintubated postoperatively, had more serious post-operative complications (Dindo-Clavien class ≥ 3), and were more likely to die within one year. Hospital and ICU lengths of stay were longer. (Table 4). Evolution of ventilatory parameters over the years is presented in eFigure 1 and 2.

## Discussion

In this study of patients undergoing dual thoracic/abdominal approach esophagectomies, we report that intraoperative ventilatory parameters can be associated with PPCs, which are associated with worse short- and long-term outcomes. While certain ventilatory parameters were associated with PPCs regardless of ventilation phase, either one- or two-lung ventilation (PPlat, RR, and DP), others depend on the ventilatory phase. While the duration of ventilation was associated with PPCs and PEEP was protective during TLV, VTe and MP were associated with PPCs during OLV.

Since underlying lung diseases such as COPD, varying degrees of chronic respiratory failure as included in the ASA score, and/or lung disease risk factors such as smoking or FEV1 are all potential risk factors for PPCs and may all participate in altering lung mechanics, we adjusted all analyses on these factors (Supplemental material, eTable 5).

Pplat was consistently associated with PPCs across all ventilation phases (Figure 2). Few studies have examined Pplat as an independent risk factor of PPCs. A retrospective study on TLV found a threshold of 16 cmH₂O to be harmful, which is higher than our average Pplat[7]. In a meta-analysis of individual data from patients undergoing TLV ventilation for major abdominal surgery, a Pplat of 24 cmH₂O was associated with PPCs but was not retained in the final multivariable model [13].

Driving pressure (DP), which integrates plateau pressure (Pplat), remained consistently associated with PPCs during both OLV and TLV (Figure 2). This finding aligns with previous studies identifying DP as the ventilatory parameter most strongly associated with postoperative pulmonary complications across major surgical populations [8,13]. Although smaller randomized trials have suggested that DP-guided ventilation could reduce PPCs, larger studies have not confirmed this benefit [18,19]. DP reflects both ventilatory settings and respiratory system mechanics (DP = Pplat – PEEP = VTe/Crs). In our cohort, VTe and PEEP were similar between groups, but Pplat was higher in patients who developed PPCs, suggesting that increased DP mainly reflected reduced dynamic compliance, which was not directly measured. Subtle compliance alterations, undetected by preoperative spirometry or clinical history, may therefore explain why no clearly “safe” threshold for Pplat or DP could be identified in our cohort, despite average Pplat values remaining below the conventional 25 cmH₂O limit[13].
Respiratory rate was an independent risk factor of PPCs across ventilation phases (Figure 2). Elevated RR, while often used to maintain normocapnia during protective ventilation, increases the number of strain cycles applied to lung tissue per unit of time. This cumulative dynamic strain may exacerbate ventilator-induced lung injury (VILI), particularly when combined with reduced compliance. Respiratory rate is underexplored as a modifiable risk factor for VILI in the operating theatre[31], while increasingly repetitive stress and strain[32] with increasing respiratory rate have been shown to promote VILI in critical care ventilation[33]. This may suggest the need to adjust RR based on compliance and DP, rather than solely on the need for end-tidal CO₂ clearance.

During the OLV phase, an increase of 0.7 mL.kg⁻¹ in VTe was associated with PPCs (Figure 2). This likely reflects the specifics of ventilatory mechanics during OLV, where the entire VTe is delivered to a single lung. If the applied VTe is not sufficiently reduced, then the single lung is in a low compliance zone of the pressure/volume relationship, thereby increasing regional strain and susceptibility to volutrauma[34]. However, there is no clear consensus on a clear “safe” range of VTe for OLV, [35,36] and the only 2 published guidelines recommend a VTe below 6 mL.kg⁻¹ [10,37]. In our cohort, despite a mean VTe < 6 mL.kg⁻¹ in both groups, VTe remained associated with PPCs. The fact that VTe was associated with PPCs only in the OLV but not the TLV phase, despite being reduced, highlights that the debate surrounding “protective” VTe in OLV remains unresolved [36].

Mechanical power (MP) was associated with PPCs only during OLV. Introduced in 2016, MP quantifies the energy delivered to the lung by ventilation, integrating VTe, RR, and pressure components [38]. In ARDS, MP correlates strongly with mortality, and similar associations have been shown intraoperatively with postoperative respiratory failure and reintubation [39]. We previously reported its relationship with PPCs in >30,000 abdominal surgery patients [9], and others have confirmed its predictive value during OLV in thoracic surgery [40,41]. In our cohort, the association between MP and PPCs likely reflects the physiology of single-lung ventilation. VTe is a risk factor only during OLV and contributes directly to MP, potentially causing harm even at levels that are conventionally considered protective. Another MP component, PEEP, can either amplify or mitigate energy delivery, depending on its effect on Pplat and DP[14,42–44]. Indeed, PEEP contributes to the static component of MP, which is either minimally deleterious or protective, while other components are cyclic and repetitively injurious [38,45]. In OLV, higher Pplat and DP despite similar VTe and PEEP between groups suggest additive strain effects, whereas during TLV, PEEP was protective, and neither VTe nor MP were associated with PPCs. These findings support individualized titration of VTe and PEEP during OLV, with MP as an integrative target for optimizing intraoperative ventilation, similarly to the results of a network meta-analysis in non-cardiothoracic surgical patients [43,44,46].

Duration of ventilation was associated with PPCs only during TLV. This introduces a concept of time-dependence of exposure to ventilatory parameters that potentially contribute to the development
of PPCs. Ventilation duration is known to be a factor associated with worse prognosis in the ICU [47]. However, few intraoperative studies suggest that prolonged intraoperative ventilation increases morbidity, such as the onset of PPCs [48,49], as in our cohort. In thoracic surgery studies, the TLV phase is negligible, lasting an average of 20-30 minutes [48]. In our cohort of esophagectomies, the TLV phase lasted 356.0 ± 107.7 minutes, while OLV lasted 172 ± 68.4 minutes. This longer duration of TLV may be the main reason duration is a risk factor only during TLV. Indeed, a post-hoc analysis of an RCT in lung-resection surgery patients integrated time into the analysis of MP [48]. In their study, MP was associated with PPCs only for durations longer than 210 minutes. In our cohort, the mean duration for OLV in the PPCs group was under their time threshold.

The incidence of PPCs in our cohort (42.7%) was higher than in large prospective surgical series (≈28%)[6]. This discrepancy likely reflects our use of EPCO definitions, which are more stringent and tailored to identify risk factors, unlike surgical audit criteria that tend to underestimate pulmonary morbidity [50]. EPCO criteria capture clinically relevant events such as non-invasive ventilation for respiratory failure, which may not be considered “major” in surgical registries but represent meaningful morbidity for anesthesiologists and intensivists.

In our study, PPCs were associated with severe postoperative complications, prolonged ICU and hospital length of stays, and increased one-year mortality, mirroring findings from external cohorts where PPCs are among the strongest risk factors of short- and long-term outcomes[6]. International benchmarks confirm PPCs as the most frequent and consequential after esophagectomy[50]. Thus, PPCs are not only common but critical determinants of postoperative course survival.

## Limitations

This study has several limitations. It is a retrospective, single-center study, which limits generalizability and allows only associations to be drawn. Some unmeasured confounders may persist, as dynamic pulmonary compliance and diffusing capacity for carbon monoxide were unavailable. The potential provider effect was not assessed, given the large number of anesthesiologists and nurse anesthetists involved. Although ventilatory management followed a shared departmental framework, some aspects that may have an effect on PPCs, such as the management of the non-dependent lung (oxygenation, CPAP, or none), were not collected and could not be taken into account. Postoperative outcomes were restricted to PPCs within seven days, without longer-term follow-up. Emergency cases were excluded to reduce bias, and statistical adjustments were pre-specified based on established PPC risk factors. Finally, external validation in multicenter prospective cohorts is needed before clinical recommendations can be made.

## Conclusion
In elective esophagectomy patients, plateau pressure, respiratory rate, and driving pressure were associated with PPCs across ventilation phases, TLV and OLV. In TLV, but not OLV, duration of ventilation was associated with increased risk of PPCs, while PEEP was protective against the risk of PPCs. In OLV only, VTe and MP were associated with PPCs.

These findings suggest that intraoperative ventilatory parameters may be targets for optimization to reduce pulmonary morbidity.

**Acknowledgements:**

1. **Assistance with the article:** The authors thank the Lille University Hospital data warehouse team for their technical assistance with data extraction.

2. **Financial support and sponsorship:** None declared

3. **Conflicts of interest:** CC received fees from Grünenthal for speaking. He also received benefits from Fisher & Paykel Healthcare: participation in meetings. He also received travel and hospitality support from Getinge AB. EK received consultancy, meeting and presentation fees from Shionogi, MSD France and Pfizer; consultancy and presentation fees from Takeda and Getinge AB; presentation fees from LFB. No potential conflict of interest relevant to this article was reported for others authors.

4. **Presentation:** Preliminary results were presented at the SFAR (Société française d'aneshtésie-réanimation) 2024 Annual Congress (Paris, France) during a communication.

**Authors' contributions**

Study concept and design: CC, EK, GL, BT

Data collection: CC, RL, DR, AB

Statistical analysis: EC and JL

Data analysis and manuscript preparation: CC, RL, EC, DR, AB, MM, EK

Manuscript review, editing and approval: all authors

**Funding statement:** No Funding Received

**Summary Statement:** Driving pressure, mechanical power and duration of ventilation are risk factors to the development of postoperative pulmonary complications in patients undergoing intraoperative ventilation for elective esophagectomy.

**Conflicts of interest:** CC received fees from Grünenthal for speaking. He also received benefits from Fisher & Paykel Healthcare: participation in meetings. He also received travel and hospitality support from Getinge AB. EK received consultancy, meeting and presentation fees from Shionogi, MSD France and Pfizer; consultancy and presentation fees from Takeda and Getinge AB; presentation fees from LFB. No potential conflict of interest relevant to this article was reported for others authors

**Clinical Trial Number:** Not Applicable
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FIGURE LEGENDS

<figure><img src="image_4.png" /><figcaption>**Figure 2:** Forest plot describing predictive multivariable models of postoperative pulmonary complications of intraoperative ventilatory parameters for postoperative pulmonary complications after esophagectomy</figcaption></figure>

<figure><img src="image_5.png" /></figure>

<figure><img src="image_6.png" /></figure>

<figure><img src="image_7.png" /></figure>

<figure><img src="image_8.png" /></figure>

<figure><img src="image_9.png" /></figure>

<figure><img src="image_10.png" /></figure>
Odds-ratios are expressed for an increase of 1 standard deviation. All predictive multivariable models were adjusted for clinical variables (age, diabetes, BMI categories, surgical approach, denutrition, FEV1, ASA≥3, smoking status, FiO2, SpO2, transfusion and intraoperative fluid loading).

AUC: area under curve; OR: odds-ratio; CI: confidence interval; VTe: end-tidal volume; P peak: Peak pressure; Pplat: plateau pressure; PEEP: Positive End Expiratory Pressure; DP: driving pressure, MP: mechanical power, ME: mechanical energy, VTe: end tidal volume.

TABLES

<caption>**Table 1:** Baseline population characteristics</caption>

<caption>**Table 2:** Intraoperative data</caption>

<caption>**Table 3:** Intraoperative ventilatory data</caption>

<caption>**Table 4:** Patients' evolution considering occurrence of postoperative pulmonary complications.</caption>

<table><caption>**Table 1.** Baseline population characteristics</caption><thead><tr><th>Characteristics</th><th>Overall (n=454)</th><th>PPCs (n=194)</th><th>No PPCs (n=260)</th></tr></thead><tbody><tr><td>Male</td><td>366/454 (80.6)</td><td>162/194 (83.5)</td><td>204/260 (83.5)</td></tr><tr><td>Age (years)</td><td>64 ± 10</td><td>64 ± 9</td><td>63 ± 10</td></tr><tr><td>Weight (kg)</td><td>77 ± 16</td><td>79 ± 16</td><td>75 ± 16</td></tr><tr><td>Predicted body weight (kg)</td><td>67 ± 8 [n=453]</td><td>67 ± 8</td><td>67 ± 8 [n=259]</td></tr><tr><td>BMI (kg.m<sup>-2</sup>)</td><td>26 ± 5</td><td>27 ± 5</td><td>25 ± 5</td></tr><tr><td><strong>ASA score</strong></td><td></td><td></td><td></td></tr><tr><td>ASA 1</td><td>46/454 (10.1)</td><td>14/194 (7.2)</td><td>32/260 (12.3)</td></tr><tr><td>ASA 2</td><td>274/454 (60.4)</td><td>107/194 (55.2)</td><td>167/260 (64.2)</td></tr><tr><td>ASA 3</td><td>132/454 (29.1)</td><td>72/194 (37.1)</td><td>60/260 (23.1)</td></tr><tr><td>ASA 4</td><td>2/454 (0.4)</td><td>1/194 (0.5)</td><td>1/260 (0.4)</td></tr><tr><td><strong>Charlson Comorbidity Score</strong></td><td>4.1 ± 1.6 [n=448]</td><td>4.3 ± 1.7 [n=190]</td><td>4.0 ± 1.5 [n=258]</td></tr><tr><td><strong>ECOG-PS</strong></td><td></td><td></td><td></td></tr><tr><td>PS 0</td><td>319/437 (73.0)</td><td>128/183 (79.9)</td><td>191/254 (75.2)</td></tr><tr><td>PS 1</td><td>109/437 (24.9)</td><td>50/183 (27.3)</td><td>59/254 (23.2)</td></tr><tr><td>PS 2</td><td>8/437 (1.8)</td><td>5/183 (2.7)</td><td>4/254 (1.6)</td></tr><tr><td>PS 3</td><td>1/437 (0.2)</td><td>1/183 (0.5)</td><td>0/254 (0.0)</td></tr><tr><td><strong>Cancer localization</strong></td><td></td><td></td><td></td></tr><tr><td>Upper esophagus</td><td>14/447 (3.1)</td><td>10 (5.0)</td><td>4 (1.6)</td></tr><tr><td>Mid esophagus</td><td>63/447 (14.1)</td><td>31 (15.6)</td><td>32 (12.6)</td></tr><tr><td>Lower esophagus</td><td>200/447 (44.7)</td><td>84 (42.2)</td><td>119 (47.0)</td></tr><tr><td>Eso-gastric junction</td><td>170/447 (38.0)</td><td>74 (37.2)</td><td>98 (38.7)</td></tr><tr><td><strong>Histology</strong></td><td></td><td></td><td></td></tr><tr><td>Adenocarcinoma</td><td>323/351 (71.6)</td><td>138/192 (69.3)</td><td>185/253 (73.1)</td></tr><tr><td>Squamous cell carcinoma</td><td>107/351 (23.7)</td><td>54/192 (27.1)</td><td>54/253 (21.3)</td></tr><tr><td>Other</td><td>21/351 (4.7)</td><td>7/192 (3.5)</td><td>14/253 (6.3)</td></tr><tr><td><strong>Tumor stage (tumor size)</strong></td><td></td><td></td><td></td></tr><tr><td>T1</td><td>57/450 (13.0)</td><td>19/193 (9.8)</td><td>41/260 (15.7)</td></tr></tbody></table>
<table><tbody><tr><td>T2</td><td>140/450 (30.8)</td><td>64/193 (32.9)</td><td>76/260 (29.2)</td></tr><tr><td>T3</td><td>242/450 (53.3)</td><td>105/193 (54.1)</td><td>137/260 (52.7)</td></tr><tr><td>T4</td><td>11/450 (2.4)</td><td>5/193 (2.7)</td><td>6/260 (2.4)</td></tr><tr><td colspan="4"><strong>Tumor stage (local lymph node spread)</strong></td></tr><tr><td>N0</td><td>264/454 (58.1)</td><td>112/194 (57.7)</td><td>152/260 (58.4)</td></tr><tr><td>N1</td><td>136/454 (30.0)</td><td>58/194 (29.9)</td><td>78/260 (30.0)</td></tr><tr><td>N2</td><td>39/454 (8.6)</td><td>17/194 (8.8)</td><td>22/260 (8.1)</td></tr><tr><td>N3</td><td>15/454 (3.3)</td><td>7/194 (3.6)</td><td>8/260 (3.1)</td></tr><tr><td><strong>Neoadjuvant chemotherapy</strong></td><td>279/454 (61.5)</td><td>113/194 (58.2)</td><td>166/260 (63.8)</td></tr><tr><td colspan="4"><strong>Medical history</strong></td></tr><tr><td>Chronic Obstructive Pulmonary Disease</td><td>42/450 (9.3)</td><td>30/193 (15.5)</td><td>12/257 (4.7)</td></tr><tr><td>Sleep apnea</td><td>33/450 (7.3)</td><td>17/193 (8.8)</td><td>16/257 (6.2)</td></tr><tr><td>Asthma</td><td>21/450 (4.7)</td><td>8/193 (4.1)</td><td>13/257 (5.1)</td></tr><tr><td>Arterial hypertension</td><td>204/454 (44.9)</td><td>99/194 (51.0)</td><td>105/260 (40.4)</td></tr><tr><td>Myocardial infarction</td><td>41/454 (9.0)</td><td>23/194 (11.9)</td><td>18/260 (6.9)</td></tr><tr><td>Atrial fibrillation</td><td>40/454 (8.8)</td><td>19/194 (9.8)</td><td>21/260 (8.1)</td></tr><tr><td>Diabetes mellitus</td><td>58/454 (12.8)</td><td>21/194 (10.8)</td><td>37/260 (14.2)</td></tr><tr><td>Peripheral vascular disease</td><td>22/449 (4.9)</td><td>12/192 (6.3)</td><td>10/257 (3.9)</td></tr><tr><td>Preoperative FEV1 (%)</td><td>93 ± 18 [n=251]</td><td>94 ± 18 [n=103]</td><td>93 ± 18 [n=148]</td></tr><tr><td>Preoperative hemoglobin (g.dl<sup>-1</sup>)</td><td>12.9 ± 1.6 [n=351]</td><td>12.9 ± 1.7 [n=192]</td><td>12.8 ± 1.5 [n=259]</td></tr><tr><td>Preoperative prealbumin (g.l<sup>-1</sup>)</td><td>0.4 ± 1.8 [n=405]</td><td>0.4 ± 1.9 [n=172]</td><td>0.4 ± 1.7 [n=233]</td></tr><tr><td>Smoking</td><td>71/454 (15.6)</td><td>39/194 (20.1)</td><td>32/260 (12.3)</td></tr></tbody></table>

Values are no./total no. (%) or mean ± standard deviation; in cases of missing data, number of available cases is reported in bracket [n].

ASA: American Society of Anesthesiologists; BMI: Body Mass Index, ECOG-PS: Eastern Cooperative Oncology Group - Performance Status; FEV1: Forced expiratory volume in one second; PPC: postoperative pulmonary complications.

<table><caption>**Table 2. Intraoperative data**</caption><thead><tr><th></th><th>Overall (n=454)</th><th>PPCs (n=194)</th><th>No PPCs (n=260)</th></tr></thead><tbody><tr><td><strong>Durations</strong></td><td></td><td></td><td></td></tr><tr><td>Duration of anesthesia (min)</td><td>527.9 ± 135.6</td><td>564.8 ± 143.4</td><td>500.6 ± 122.7</td></tr><tr><td>Duration of OLV (min)</td><td>172.7 ± 68.4</td><td>182.1 ± 73.5</td><td>165.7 ± 63.6</td></tr><tr><td>Duration of TLV (min)</td><td>356.0 ± 107.7</td><td></td><td></td></tr><tr><td>Duration of surgery (min)</td><td>446.7 ± 136.6</td><td>477.1 ± 141.7</td><td>424.2 ± 128.5</td></tr><tr><td><strong>Surgery</strong></td><td></td><td></td><td></td></tr><tr><td>Ivor-Lewis</td><td>437 (96.3)</td><td>180 (96.7)</td><td>255 (98.1)</td></tr><tr><td>Mc Keown</td><td>17 (3.7)</td><td>14 (7.0)</td><td>5 (1.9)</td></tr><tr><td><strong>Surgical incision</strong></td><td></td><td></td><td></td></tr><tr><td>TMIE</td><td>289 (63.7)</td><td>121 (62.4)</td><td>168 (64.9)</td></tr><tr><td>HMIE</td><td>109 (24.0)</td><td>36 (18.6)</td><td>73 (28.1)</td></tr><tr><td>Open</td><td>56 (12.3)</td><td>37 (19.1)</td><td>19 (7.3)</td></tr><tr><td>Robot-assisted</td><td>59 (13.0)</td><td>22 (11.1)</td><td>37 (14.7)</td></tr><tr><td><strong>Anesthesia</strong></td><td></td><td></td><td></td></tr><tr><td>Epidural analgesia</td><td>435 (95.8)</td><td>184 (94.8)</td><td>243 (96.4)</td></tr></tbody></table>
<table><tr><td>Fluid loading (ml.kg<sup>-1</sup>.h<sup>-1</sup>)</td><td>6.5 ± 3.9</td><td>6.3 ± 2.3</td><td>6.6 ± 4.8</td></tr><tr><td>Bleeding (ml)</td><td>300 [100 - 450]</td><td>300 [150 - 600]</td><td>200 [100 - 400]</td></tr><tr><td>Transfusion</td><td>25 (5.5)</td><td>18 (9.4)</td><td>7 (2.8)</td></tr></table>

Values are number (%), mean± standard deviation or median [interquartile range]. HMIE: hybrid minimally invasive esophagectomy; OLV: one-lung ventilation; TMIE: totally mini-invasive esophagectomy; TLV: two-lung ventilation.

<table><caption>Table 3. Intraoperative ventilatory data</caption><thead><tr><th>Ventilation parameters*</th><th>Overall (n=454)</th><th>PPCs (n=194)</th><th>No PPCs (n=260)</th><th>Standardized difference [95%CI] (%)</th><th>p-value</th></tr></thead><tbody><tr><td><strong>One-lung ventilation</strong></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>VTe (ml)<sup>1</sup></td><td>354 ± 44 [n=440]</td><td>357 ± 46 [n=184]</td><td>352 ± 43 [n=256]</td><td>12.8 [-6.5 ; 44.4]</td><td>0.18</td></tr><tr><td>VTe (ml.kg<sub>PBW</sub><sup>-1</sup>)</td><td>5.3 ± 0.7 [n=440]</td><td>5.4 ± 0.7 [n=184]</td><td>5.2 ± 0.7 [n=256]</td><td>21.1 [2.0 ; 40.1]</td><td>0.029</td></tr><tr><td>Ppeak (cm H<sub>2</sub>O)</td><td>31 ± 4 [n=441]</td><td>31 ± 4 [n=184]</td><td>30 ± 4 [n=257]</td><td>31.7 [12.6 ; 50.7]</td><td>0.001</td></tr><tr><td>Pplat (cm H<sub>2</sub>O)</td><td>23 ± 4 [n=412]</td><td>25 ± 4 [n=170]</td><td>22 ± 3 [n=242]</td><td>54.7 [34.7 ; 74.4]</td><td>&lt;0.001</td></tr><tr><td>Pplat&gt;25 cm H<sub>2</sub>O</td><td>110/412 (26.7)</td><td>68/170 (40.0)</td><td>42/242 (17.4)</td><td>51.7 [31.8 ; 71.7]</td><td>&lt;0.001</td></tr><tr><td>PEEP (cm H<sub>2</sub>O)</td><td>7.1 ± 1.5 [n=441]</td><td>7.1 ± 1.5 [n=184]</td><td>7.1 ± 1.5 [n=257]</td><td>-1.4 [-20.4 ; 17.6]</td><td>0.88</td></tr><tr><td>DP (cm H<sub>2</sub>O)</td><td>16.3 ± 4.0 [n=412]</td><td>17.5 ± 4.3 [n=170]</td><td>15.4 ± 3.4 [n=242]</td><td>54.4 [34.4 ; 74.4]</td><td>&lt;0.001</td></tr><tr><td>DP&gt;15 cm H<sub>2</sub>O</td><td>222/412 (53.9)</td><td>111/170 (65.3)</td><td>111/242 (45.9)</td><td>39.9 [20.3 ; 59.4]</td><td>&lt;0.001</td></tr><tr><td>RR (cycles.min<sup>-1</sup>)</td><td>22 ± 3 [n=441]</td><td>23 ± 3 [n=184]</td><td>22 ± 3 [n=257]</td><td>17.1 [-2.0 ; 36.1]</td><td>0.079</td></tr><tr><td>EtCO<sub>2</sub> (mm Hg)</td><td>40 ± 5 [n=440]</td><td>39 ± 5 [n=184]</td><td>41 ± 5 [n=256]</td><td>-31.8 [-50.9 ; -12.7]</td><td>0.001</td></tr><tr><td>Mechanical power (J.min<sup>-1</sup>)</td><td>18.0 ± 4.7 [n=418]</td><td>18.4 ± 4.7 [n=173]</td><td>17.6 ± 4.6 [n=245]</td><td>18.0 [-1.5 ; 37.6]</td><td>0.070</td></tr><tr><td>FiO<sub>2</sub> (%)</td><td>74 ± 11 [n=412]</td><td>74 ± 11 [n=183]</td><td>74 ± 11 [n=250]</td><td>-0.6 [-19.7 ; 18.5]</td><td>0.95</td></tr><tr><td>SpO<sub>2</sub> (%)</td><td>95 ± 2 [n=435]</td><td>95 ± 2 [n=183]</td><td>95 ± 2 [n=252]</td><td>-4.1 [-23.2 ; 15.0]</td><td>0.67</td></tr><tr><td>Duration of ventilation (min)</td><td>173 ± 68 [n=451]</td><td>182 ± 73 [n=192]</td><td>166 ± 64 [n=259]</td><td>23.8 [5.0 ; 42.6]</td><td>0.014</td></tr><tr><td><strong>Two-lung ventilation</strong></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>VTe (ml)</td><td>463 ± 45 [n=443]</td><td>463 ± 47 [n=186]</td><td>464 ± 44 [n=257]</td><td>-2.5 [-21.4 ; 16.4]</td><td>0.80</td></tr><tr><td>VTe (ml.kg<sub>PBW</sub><sup>-1</sup>)</td><td>6.9 ± 0.6 [n=443]</td><td>7.0 ± 0.6 [n=186]</td><td>6.9 ± 0.6 [n=257]</td><td>5.5 [-13.4 ; 24.4]</td><td>0.57</td></tr><tr><td>Ppeak (cm H<sub>2</sub>O)</td><td>25 ± 4 [n=444]</td><td>25 ± 4 [n=186]</td><td>25 ± 4 [n=258]</td><td>24.0 [5.0 ; 42.9]</td><td>0.014</td></tr><tr><td>Pplat (cm H<sub>2</sub>O)</td><td>19 ± 3 [n=419]</td><td>19 ± 3 [n=173]</td><td>18 ± 3 [n=246]</td><td>37.6 [18.0 ; 57.3]</td><td>&lt;0.001</td></tr><tr><td>Pplat&gt;25 cm H<sub>2</sub>O</td><td>4/419 (1.0)</td><td>4/173 (2.3)</td><td>0/246 (0.0)</td><td>21.8 [0.9 ; 42.6]</td><td>NA</td></tr><tr><td>PEEP (cm H<sub>2</sub>O)</td><td>6.7 ± 1.2 [n=444]</td><td>6.7 ± 1.3 [n=186]</td><td>6.8 ± 1.1 [n=258]</td><td>-7.5 [-26.4 ; 11.4]</td><td>0.43</td></tr><tr><td>DP (cm H<sub>2</sub>O)</td><td>11.8 ± 2.7 [n=419]</td><td>12.5 ± 2.8 [n=173]</td><td>11.4 ± 2.5 [n=246]</td><td>42.9 [23.2 ; 62.6]</td><td>&lt;0.001</td></tr><tr><td>DP&gt;15 cm H<sub>2</sub>O</td><td>39/419 (9.3)</td><td>24/173 (13.9)</td><td>15/246 (6.1)</td><td>26.2 [6.5 ; 45.8]</td><td>0.007</td></tr><tr><td>RR (cycles.min<sup>-1</sup>)</td><td>19 ± 3 [n=444]</td><td>19 ± 2 [n=186]</td><td>18 ± 2 [n=258]</td><td>31.9 [12.9 ; 50.8]</td><td>&lt;0.001</td></tr><tr><td>EtCO<sub>2</sub> (mm Hg)</td><td>37 ± 3 [n=440]</td><td>37 ± 3 [n=184]</td><td>38 ± 3 [n=256]</td><td>-20.5 [-39.5 ; -1.4]</td><td>0.034</td></tr><tr><td>Mechanical power (J.min<sup>-1</sup>)</td><td>16.6 ± 4.6 [n=418]</td><td>17.2 ± 4.6 [n=175]</td><td>16.2 ± 4.6 [n=243]</td><td>23.6 [4.1 ; 43.1]</td><td>0.018</td></tr><tr><td>FiO<sub>2</sub> (%)</td><td>50 ± 8 [n=432]</td><td>50 ± 8 [n=182]</td><td>50 ± 8 [n=250]</td><td>3.6 [-15.5 ; 22.8]</td><td>0.71</td></tr></tbody></table>
<table><tr><td>SpO<sub>2</sub> (%)</td><td>98 ± 1 [n=434]</td><td>98 ± 1 [n=182]</td><td>98 ± 1 [n=252]</td><td>-16.0 [-35.1 ; 3.2]</td><td>0.10</td></tr><tr><td>Duration of ventilation (min)</td><td>356 ± 108 [n=453]</td><td>384 ± 118 [n=193]</td><td>335 ± 95 [n=260]</td><td>45.1 [26.2 ; 64.0]</td><td>&lt;0.001</td></tr></table>

Values are no./total no. (%) or mean ± standard deviation; in cases of missing data, number of available cases is reported in bracket [n].

* all parameters are mean over the specified ventilation phase.

VTe: end-tidal volume; PBW: Predicted body weight; Ppeak: Peak pressure; Pplat: plateau pressure;

PEEP: Positive End Expiratory Pressure; DP: driving pressure; RR: respiratory rate; EtCO₂: End-tidal carbon dioxide; SpO₂: pulsed oxygen saturation; FiO₂: Inspired fraction of oxygen, NA: not applicable, CI: confidence interval.

<table><caption>Table 4. Patients' evolution considering occurrence of postoperative pulmonary complication.</caption><thead><tr><th></th><th>PPCs (n= 194)</th><th>No PPCs (n= 260)</th><th>p-value</th></tr></thead><tbody><tr><td>Dindo- Clavien classification≥ 3 (%)</td><td>134/158 (84.8)</td><td>72/209 (34.4)</td><td>&lt;0.001</td></tr><tr><td>Endotracheal intubation (%)</td><td>43/194 (22.2)</td><td>3/260 (1.2)</td><td>&lt;0.001</td></tr><tr><td>ICU length of stay</td><td>7.0 [5.0 – 11.0]</td><td>5.0 [4.0 – 6.5]</td><td>&lt;0.001</td></tr><tr><td>Hospital length of stay</td><td>19.0 [14.0 – 28.0] [193]</td><td>12.5 [10.0 – 16.0]</td><td>&lt;0.001</td></tr><tr><td>Death at 28 days (%)</td><td>3/194 (1.5)</td><td>0/259 (0.0)</td><td>NA</td></tr><tr><td>Death at 1 year (%)</td><td>26/149 (17.4)</td><td>14/194 (7.2)</td><td>NA</td></tr></tbody></table>

Values are no./total no. (%) or mean ± standard deviation; in cases of missing data, number of available cases is reported in bracket [n]. ICU: intensive care unit, PPC: postoperative pulmonary complication.

NA: not applicable.