Airway pressure and flow monitoring.

PURPOSE OF REVIEW: We report on the evolution of airway pressure and flow monitoring from a pathophysiological tool to the cornerstone of ventilator-induced lung injury (VILI) prevention.

RECENT FINDINGS: Protective ventilatory strategies are based on reduction of volume and pressures delivered to the lungs. New evidence, which will need confirmation in further studies, suggests that transpulmonary pressure (alveolar pressure minus pleural pressure), could be used to titrate both the positive end-expiratory pressure (PEEP) level and the inspiratory pressure applied by the ventilator. A limited number of animal studies are strongly supporting a role for inspiratory flow on the development of VILI.Moreover, different airway flow patterns may affect secretion movement, both global, to the alveoli or the glottis, and regional, from lower to higher compliance regions. This intra-lung transfer may be a primary mechanism for the propagation of infections and inflammatory mediators.Alternative monitoring techniques (among others) are the rapid interrupter technique, which can be used to measure airway resistance and patients' inspiratory effort and the forced oscillation technique which could become a bedside technique to estimate recruitment/derecruitment and titrate PEEP.

SUMMARY: Airway pressure and flow monitoring is essential for VILI prevention and for an appropriate setting of mechanical ventilation.