The effect of body mass index on pressure controlled ventilator settings

In this article, we present an approach to determine the most indulgent inspiratory pressure and inspiratory time for pressure controlled ventilation as a function of BMI for a patient with healthy lungs. The lung mechanics are strongly influenced by obesity as airway resistance increases and the lung compliance decreases with increasing BMI. Based on a linear single compartment model of the lung and parameter values depending on the BMI, a ventilator setting minimizing inspiration pressure PI for a given minute volume can be determined. First a constant PEEP of 10 cmH20 is assumed. The results of the optimization show that an increased inspiratory pressure PI as well as a slightly increased inspiratory time tI are necessary to achieve a given minute volume with increasing BMI. In the second step, a BMI-dependent PEEP is added, illustrating different effects of the BMI. The proposed approach is a first step to ensure efficient and safe, patient-individualized mechanical ventilation for obese patients.