Obesity Alters Lung Mechanics in Robotic Surgery


Intraoperative lung protective ventilation strategies using standardized tidal volumes based on predicted body weight have proven beneficial, but attempts to standardize positive end expiratory pressure (PEEP) settings have not robustly accounted for body habitus or dynamic surgical conditions. Laparoscopic abdominal surgery in Trendelenburg (head-down) is an increasingly common surgical modality that presents a unique physiological challenge to the pulmonary system. In order to delineate the impact of body habitus, pneumoperitoneum, and surgical positioning on intraoperative pulmonary mechanics we conducted an observational study of patients undergoing robotic assisted laparoscopic abdominal surgery in Trendelenburg position. Using esophageal manometry, we partitioned the mechanical properties of the respiratory system into its lung and chest wall components and evaluated the effects of pneumoperitoneum, surgical position, and body mass index (BMI) on transpulmonary pressures, airway and transpulmonary driving pressures, and lung elastance. We hypothesized that increasing BMI would be associated with evidence of increasing atelectasis, increased driving pressures, and elevated lung elastance and that these changes would be exacerbated by pneumoperitoneum and Trendelenburg positioning.

Full Title of Study: “Dynamic Surgical Conditions and Body Habitus Independently Impair Pulmonary Mechanics During Robotic Assisted Laparoscopic Surgery: A Cross-Sectional Study”

Study Type

  • Study Type: Observational
  • Study Design
    • Time Perspective: Cross-Sectional
  • Study Primary Completion Date: July 12, 2019


  • Other: no intervention
    • no intervention – observational only

Arms, Groups and Cohorts

  • Lean
    • BMI < 25
  • overweight
    • BMI 25 – 29.9
  • class i obesity
    • BMI 30 -34.9
  • class ii obesity
    • BMI 35 – 39.9
  • class iii obesity
    • BMI >= 40

Clinical Trial Outcome Measures

Primary Measures

  • Transpulmonary pressure
    • Time Frame: during the surgical procedure

Participating in This Clinical Trial

Inclusion Criteria

Inclusion criteria were presentation for robotic assisted laparoscopic abdominal surgery in the supine position, age ≥ 18 years, and ability to provide informed consent

Exclusion Criteria

Exclusion criteria included intrinsic lung disease, ≥ 20 pack year smoking history, reactive airways disease, home oxygen requirement, inability to provide informed consent, emergent surgery, or esophageal pathology (i.e., strictures, varices, history of esophageal dilatation or surgery).

Gender Eligibility: All

Minimum Age: 18 Years

Maximum Age: N/A

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • University of Vermont Medical Center
  • Provider of Information About this Clinical Study
    • Principal Investigator: William G Tharp, Assistant Professor – University of Vermont Medical Center

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