Driving Pressure and Postoperative Pulmonary Complications in Thoracic Surgery

Pulmonary complications are the most common complication in thoracic surgery and the leading cause of mortality.Therefore, lung protection is utmost important, and protective ventilation is strongly recommended in thoracic surgery. Protective ventilation is a prevailing ventilatory strategy in these days and is comprised of small tidal volume, limited inspiratory pressure, and application of positive end-expiratory pressure. However, several retrospective studies recently suggested that tidal volume, inspiratory pressure, and positive end-expiratory pressure are not related to patient outcomes, or only related when they influenced the driving pressure. Recently, the investigators reported the first prospective study about the driving pressure-guided ventilation in thoracic surgery. PEEP was titrated to bring the lowest driving pressure in each patient and applied throughout the one lung ventilation. The application of individualized PEEP reduced the incidence of pulmonary complications.However, that study was small size single center study with 312 patients. Thus, investigators try to perform large scale multicenter study. Through this study investigators evaluate that driving pressure-guided ventilation can reduce the incidence of postoperative pulmonary complications compared with conventional protective ventilation in thoracic surgery.

Nowdays, the usual setting of protective ventilation during one lung ventilation is tidal volume (VT) 5 ml/kg of predicted body weight, positive end-expiratory pressure (PEEP) 5 cm H2O and plateau pressure (Pplat) less than 25 cmH2O.

However, a high incidence of postoperative pulmonary complications is still being observed even with a protective ventilatory strategy.

Driving pressure is \[Pplat - PEEP\] and is the pressure required for the alveolar opening. Static lung compliance (Cstat) is expressed as \[VT / (Pplat - PEEP)\]. Thus, driving pressure is also expressed as \[VT / Cstat\]. Driving pressure has an inverse relationship with Cstat and orthodromic relationship with VT according to this formula. High driving pressure indicates poor lung condition with decreased lung compliance.

Thus, investigator try to prove that driving pressure limited ventilation is superior in preventing postoperative pulmonary complications to existing protective ventilation in large scale multicenter study.

Recruit maneuver perform all group after intubation (stepwise increase of positive end expiratory pressure 5,10,15 cmH2O with tidal volume 5mL/kg).

The control arm receives existing conventional protective ventilation with tidal volume of 5mL/kg of ideal body weight and PEEP of 5 cmH2O during one-lung ventilation.

The driving pressure arm receives driving pressure limited ventilation with tidal volume of 5mL/kg of ideal body weight and individualized PEEP. Individualized PEEP is adjusted to minimize driving pressure, it find through decremental PEEP titration from 10 to 2 cmH2O during one-lung ventilation.

Eligibility Criteria:
Inclusion Criteria:

Adults older than or equal to 19 years with American Society of Anesthesiologists physical status Ⅰ-Ⅲ Patient who undergoes one-lung ventilation (more than 60 minutes) for elective thoracic surgery

Exclusion Criteria:

1. The American Society of Anesthesiologists (ASA) Physical Status classification greater than or equal to 4
2. Symptoms of heart failure (hypertension, urination, pulmonary edema, left ventricular outflow rate \<45%) or preoperative vasopressors
3. Patient who is received oxygen therapy and ventilation care
4. large emphysema and pneumothorax
5. pregnancy and lactation
6. patients participating in similar studies
7. Joint with other operation
8. Patient who rejects being enrolled in the study
9. Patients with elevated intracranial pressure
10. Patients with peripheral neuropathy or blood circulation disorders
11. Patients with hematology disease
12. Congenital heart disease with shunt