The purpose of this pilot study is to identify the optimal way to ventilate patients during abdominal surgery in order to reduce the amount of post-operative pulmonary complications in patients at moderate and high-risk for them.
The investigators plan to prospectively compare two methods to individualize Positive End Expiratory Pressure (PEEP) settings in the operating room during abdominal surgery: (1) Maximization of respiratory compliance during a decremental PEEP titration, and (2) Prevention of negative end-expiratory transpulmonary pressures. The investigators will exploit the usual intraoperative requirement for a naso/orogastric tube to assess transpulmonary pressures,and respiratory mechanics measurements from anesthesia machines to titrate PEEP. The investigators will measure biomarkers of lung injury and lung function to compare those methods between themselves and to the control group. In the process, the investigators will assess the ease and reliability of anesthesia teams in implementing the methods. These data will allow us to determine the PEEP strategy best suited for the full-scale trial, and to estimate the degree of separation the experimental lung protective approach will have from the protocolized usual care control settings.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
SINGLE
Enrollment
40
PEEP will be set at the maximum static respiratory system compliance during a descending PEEP titration curve.
We will use transpulmonary pressure values obtained using an naso/orogastric tube during the operative procedure to titrate PEEP intraoperatively.
Massachusetts General Hospital
Boston, Massachusetts, United States
Intraoperative driving pressure
We will assess intraoperative driving pressure to evaluate respiratory mechanics during surgery.
Time frame: During abdominal surgery
Intraoperative transpulmonary pressure
We will assess intraoperative transpulmonary pressure to evaluate respiratory mechanics during surgery.
Time frame: During abdominal surgery
Intraoperative respiratory system compliance
We will assess intraoperative respiratory system compliance to evaluate respiratory mechanics during surgery.
Time frame: During abdominal surgery
Intraoperative positive end-expiratory pressure (PEEP) levels
We will assess intraoperative PEEP values and their variability between patients and during surgery.
Time frame: During abdominal surgery
Intraoperative gas exchange
We will assess intraoperative oxygenation and carbon dioxide elimination.
Time frame: During abdominal surgery
Plasma levels of biomarkers of lung injury
We will assess plasma concentrations of biomarkers of lung injury before and after surgery, including biomarkers of inflammation (interleukin-6, IL-6, interleukin-8, IL-8), epithelial injury (soluble form of the receptor for advanced glycation end-products, sRAGE, Club Cell protein-16, CC16), endothelial injury (angiopoietin-2, Ang-2), and endothelial-derived coagulation activation (plasminogen activator inhibitor-1, PAI-1).
Time frame: During abdominal surgery
Postoperative Pulmonary Complications
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We will assess the incidence and absolute number of postoperative pulmonary complications within the first 7 postoperative days.
Time frame: Within the first 7 postoperative days.