Assessing Ventilator Safety in Patients on Pressure-Support Ventilation (ASOP)

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. We will describe the relationship between three different assessment methods for risk of self-induced lung injury and compare them to a gold standard measurement.

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.

Measuring dynamic airway driving pressure and static airway driving pressure during pressure support breath, and static airway driving pressure during a volume control breath. Measuring airway occlusion pressure during pressure support breath.

Measuring static and dynamic esophageal driving pressure during pressure support breath, and esophogeal pressure change during airway occlusion maneuver.

Driving pressure in centimeters of water measured with inspiratory hold on Servo Ventilator in pressure-support ventilation.

Driving pressure in centimeters of water measured with Phillips Respironics NM3 device in pressure-support ventilation.

Airway driving pressure in centimeters of water measured with inspiratory hold in volume control/assist control.

Transpulmonary driving pressure in centimeters of water measured via esophageal balloon with inspiratory hold in volume control/assist control.

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

Beitler JR, Malhotra A, Thompson BT. Ventilator-induced Lung Injury. Clin Chest Med. 2016 Dec;37(4):633-646. doi: 10.1016/j.ccm.2016.07.004. Epub 2016 Oct 14.

Slutsky AS, Ranieri VM. Ventilator-induced lung injury. N Engl J Med. 2013 Nov 28;369(22):2126-36. doi: 10.1056/NEJMra1208707. No abstract available. Erratum In: N Engl J Med. 2014 Apr 24;370(17):1668-9.

Sottile PD, Albers D, Smith BJ, Moss MM. Ventilator dyssynchrony - Detection, pathophysiology, and clinical relevance: A Narrative review. Ann Thorac Med. 2020 Oct-Dec;15(4):190-198. doi: 10.4103/atm.ATM_63_20. Epub 2020 Oct 10.

Grieco DL, Menga LS, Eleuteri D, Antonelli M. Patient self-inflicted lung injury: implications for acute hypoxemic respiratory failure and ARDS patients on non-invasive support. Minerva Anestesiol. 2019 Sep;85(9):1014-1023. doi: 10.23736/S0375-9393.19.13418-9. Epub 2019 Mar 12.

Hess DR. Ventilator waveforms and the physiology of pressure support ventilation. Respir Care. 2005 Feb;50(2):166-86; discussion 183-6.

Mauri T, Yoshida T, Bellani G, Goligher EC, Carteaux G, Rittayamai N, Mojoli F, Chiumello D, Piquilloud L, Grasso S, Jubran A, Laghi F, Magder S, Pesenti A, Loring S, Gattinoni L, Talmor D, Blanch L, Amato M, Chen L, Brochard L, Mancebo J; PLeUral pressure working Group (PLUG-Acute Respiratory Failure section of the European Society of Intensive Care Medicine). Esophageal and transpulmonary pressure in the clinical setting: meaning, usefulness and perspectives. Intensive Care Med. 2016 Sep;42(9):1360-73. doi: 10.1007/s00134-016-4400-x. Epub 2016 Jun 22.