Assessing Ventilator Safety in Patients on Pressure-Support Ventilation

Ventilator-induced lung injury (VILI) is known to cause significant morbidity and mortality in patients with acute respiratory failure. Most studies on VILI have involved the effects of inappropriate (often excessive) mechanical ventilator settings. More recently, it has been noted that similar lung damage can be caused by large, patient generated, uncontrolled tidal volumes and driving pressures, which has been termed "self-induced lung injury," or SILI.

Pressure-support ventilation (PSV) is a common mechanical ventilation mode often used in patients with active inspiratory efforts to help reduce patient inspiratory work and improve comfort. PSV effectively allows spontaneously breathing patients to determine their breath flow-rate and breath duration, eliminating flow and cycle dyssynchrony. However, pressure support ventilation does not allow for physicians to control tidal volume or driving pressure. The risk of SILI may thus be increased with PSV.

Several different methods have been proposed to address these challenges. However, to date none of these methods have been compared to assess for concordance in their ability to indicate an increased risk of self-induced lung injury. ASOP is a prospective cohort study comparing three methods for assessing risk of self-induced lung injury in patients with acute respiratory failure being managed with pressure-support ventilation.

Inclusion criteria

• Adult patients age ≥18 years with acute respiratory failure receiving invasive mechanical ventilation
• Managed in pressure-support mode of ventilation

Exclusion criteria

• Actively undergoing a spontaneously awakening trial or SAT
• Patient or surrogate is unable to provide informed consent
• Currently pregnant
• Currently incarcerated
• Acute exacerbation of an obstructive lung disease
• Known esophageal varices or any other condition for which the attending physician deems an orogastric catheter to be unsafe
• Esophageal, gastric or duodenal surgical procedures within the last 6 months