Effects of Obesity and Surgical Conditions on the Stress-Index of Intraoperative Ventilation

Impaired intraoperative lung mechanics arise from both patient and procedural factors and results in heterogenous regions of atelectasis or overdistention, which can lead to ventilator induced lung injury (VILI). Identifying, and consequent optimization of ventilator settings are still in evolution. The stress-index (SI), derived from the shape of the pressure-time curve during inflation, can identify ventilator settings associated with tidal under- or over-inflation. We hypothesized that elevated body mass index (BMI) and use of Trendelenburg positioning would lead to increasing low-volume lung stress.