NIV With Airway Washout for Dual Limb Ventilation: Improvement in Minute Ventilation

In an acute setting, Non-invasive ventilation (NIV) is a method of delivering respiratory support without using an endotracheal tube. It's a first-line treatment for specific conditions like COPD exacerbations and acute cardiogenic pulmonary edema. NIV aims to improve gas exchange, reduce work of breathing, avoid intubation, and reduce complications.

For patients with COPD exacerbations and acute cardiogenic pulmonary edema NIV is a first line therapy. NIV is also considered for other conditions like acute respiratory failure due to asthma exacerbation and in immunocompromised individuals with acute respiratory insufficiency. Additionally, it can be used in post-operative respiratory failure, for difficult weaning, and to prevent post-extubation failure.

NIV has been shown to result in overall better outcomes than mechanical ventilation with reduced mortality and morbidity, fewer ICU acquired infections improved lung function and shorter ICU stays. The severity of the respiratory insufficiency influences the likelihood of successful NIV. One factor associated with respiratory sufficiency is respiratory dead space. This is the volume in the respiratory apparatus that does not partake in gas exchange and in the ventilated patient includes the volume in the equipment, the conductive airways and pathological respiratory tissue. A high dead-space fraction early in the course of the illness is association with increased risk of death.9 Particularly in patients that have a small tidal volume and high respiratory rate, or patients with an increased physiological dead space due to lung disease, a change in instrumental dead space can have a large impact on alveolar minute ventilation. Improved alveolar ventilation can improve CO2 elimination and help to reduce respiratory acidosis as well as improve oxygen delivery.10, 11 This can consequently reduce the respiratory effort required by the patient. 12 If the physician instead chooses to keep arterial CO2 concentration (PaCO2) constant, a reduction of instrumental dead space will allow a reduction of tidal volume, plateau pressure, driving pressure, or a reduction of the respiratory rate and thus a reduction in work of breathing.

NIV with washout improves ventilation compared to conventional NIV by reducing expired air in each breath. This may result in faster normalization of ventilatory gasses and a reduced work of breathing, the patient may improve more rapidly as alveolar ventilation is improved. Or, allow for a reduction in pressure for similar ventilatory benefits, potentially improving NIV tolerance and therapy adherence. In stable COPD patients, NIV with Airway Washout resulted in a significant reduction in minute ventilation compared to conventional NIV. This was approximately 19% lower with OptiNIV compared to conventional NIV.15 In this study minute ventilation will be calculated from the RR and Vt retrieved from the ventilator to asses improvement in ventilation over the study period, this feasibility pilot aims to establish efficacy of airway washout and whether the increased leak required for dead space flushing does not impact safety, usability and performance. When airway washout for dual limb ventilators becomes widely available it may improve NIV therapy efficacy by improving ventilation or reducing the pressure needed for a similar level of ventilatory support.