Postoperative Pulmonary Complications in Robotic Versus Non-robotic Laparoscopic Surgery
Condition: Postoperative Respiratory Complication
Study type: Observational

Summary: 
      This secondary analysis aims to identify factors associated with the development of
      postoperative pulmonary complications (PPCs) in patients undergoing abdominal surgery,
      pooling and analyzing the data of two worldwide prospective studies, the 'Epidemiology,
      Practice of Ventilation and Outcome for Patients at Increased Risk of Postoperative Pulmonary
      Complications' (LAS VEGAS, NCT01601223) and the 'Assessment of Ventilatory management during
      general AnesThesia for Robotic surgery and its effects on postoperative pulmonary
      complications' (AVATaR, NCT02989415).

      The primary aim is to compare the incidence of PPCs between patients undergoing non-robotic
      surgery versus patients undergoing robot-assisted surgery. One secondary aim is to determine
      which factors are associated with the occurrence of PPCs. The investigators hypothesize that
      differences in the occurrence of PPCs between the two surgery groups are more driven by
      differences in duration of anesthesia than by the intensity of ventilation.
    

Detailed description: 
      This study involves a preplanned analysis of a merged database comprising individual patient
      data from two global observational studies on ventilation and postoperative pulmonary
      complications (PPCs). Both study protocols, the LAS VEGAS and AVATaR were approved by a
      central Institutional Review Board and local ethics committees, with written informed consent
      obtained as per local legislation. The pooled database, including modifications for patient
      categories, does not require additional ethical approval or informed consent. The analysis
      will adhere to the Strengthening the Reporting of Observational Studies in Epidemiology
      (STROBE) Statement.

      Patients:

        -  The LAS VEGAS study includes patients undergoing general anesthesia with invasive
           ventilation for elective and non-elective surgeries.

        -  The AVATaR study includes patients aged over 18 undergoing robot-assisted surgery (RAS)
           for abdominal procedures.

      Baseline Patient Characteristics:

      - Key variables extracted from LAS VEGAS and AVATaR include demographic data, smoking status,
      comorbidities (chronic heart disease, obstructed sleep apnea syndrome, anemia, chronic kidney
      disease), and details about anesthesia and surgery.

      Ventilation Variables:

        -  Ventilation-related variables extracted from the database include inspiratory pressure,
           plateau pressure, positive end-expiratory pressure, tidal volume, respiratory rate,
           fraction of inspired oxygen, peripheral oxygen saturation, end-tidal carbon dioxide.

        -  Mode of ventilation is classified as volume-controlled, pressure-controlled (including
           volume-guarantee pressure-controlled), and others.

      Intensity of mechanical ventilation will be studied by three different estimators: the
      driving pressure, driving pressure multiplied by four plus respiratory rate and mechanical
      power.

      For the statistical analysis medians with interquartile ranges, or as number with
      percentages, will be used as appropriate. Differences between the two groups of patients will
      be analyzes by Fisher or Wilcoxon test as appropriate. Key variables will be plotted by the
      cumulative distribution plots.

      Numbers of available patients who meet inclusion criteria will represent our cohort of
      patients. The investigators estimated a 10 % of drop off for additional exclusion criteria.
      For this reason the enrollment of patients cannot be actual but just anticipated. The main
      analysis will be an univariable followed by a multivariable model including known risk
      factors for PPCs, intensity of ventilation and group (laparoscopic versus robotic surgery),
      covariates will be entered in the model. Logistic regression analysis will be performed for
      studying the association between PPCs and intensity of ventilation and duration of
      anesthesia. In case of relevant co-linearity of independent variables, separate models will
      be built excluding co-linear variables and the performances of the different models will be
      assessed using the corrected Akaike information criterion. In case of an association between
      RAS and PPCs: a mediation analysis to investigate the relationship between PPC and surgical
      approach will be conducted. In addition a matched-cohort analysis in patients with similar
      length of mechanical ventilation and intensity of ventilation will be performed. The
      mediation analysis will be reported according to the "A Guideline for Reporting Mediation
      Analyses" (AGReMA) statement. R Project for Statistical Computing will be used for analyzing
      data.

      The analysis aims to compare incidences of PPCs after laparoscopic non-robotic and RAS
      abdominal surgeries, exploring associations with patient, surgery, and anesthesia factors.
    

Intervention name(s): Robot-assisted laparoscopic surgery; Conventional (non-robotic) laparoscopic surgery
Intervention type(s): Procedure; Procedure
Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Surgical patients receiving invasive mechanical ventilation for laparoscopic or
        robot-assisted laparoscopic surgery
      
Keywords: Postoperative pulmonary complications; Laparoscopic; Robotic Surgery; Mechanical Ventilation