Quantification of Inspiratory Effort Through Nasal Pressure in Patients Undergoing Weaning From Invasive Mechanical Ventilation and Correlation With Clinical Outcomes

Weaning from invasive mechanical ventilation (MV) constitutes a fundamental procedure in intensive care, covering up to 50% of time spent on ventilation (1). Endotracheal tube (ETT) removal might be an important but delicate step in intensive care setting. Failure and subsequent need for re-intubation can occur in up to 20% of cases leading to a significant increase in mortality rates (24%), longer hospital stay and prolonged need for ventilation. Comorbidities such as obesity, COPD and cardiac related diseases might further increase this risk reaching up to 60% of failure in extubation. In this scenario, accurate predictors of weaning failure are far welcomed. The recurrence of respiratory failure after extubation might considerably raise rates of failure, probably due to increased work of breathing in patients after ETT removal. Most recent guidelines on the use of non-invasive ventilation (NIV) suggest using NIV after ETT removal in subjects with high risk of failure. NIV could contribute to reduce work of breathing hence preventing the onset of respiratory failure after extubation. Therefore, measuring inspiratory effort and its variation in weaned patients might help in identifying patients with significant risk of failing extubation. Esophageal pressure swings (DeltaPES) can be measured through a nasogastric tube with a pressure transducer located in the inferior part of the esophagus. DeltaPES is an extremely precise and accurate method to quantify inspiratory effort, however its use in daily clinical practice is limited due to the invasive nature of the maneuver, elevated costs and need for considerable clinical training of operators. Physiological studies have shown a correlation between nasal pressure measured at nostril entrance and esophageal pressure (which in turn is a measure of respiratory effort .

Therefore, measuring nasal pressure could represent a method to quantify inspiratory effort non-invasively, proving to be useful in daily clinical practice.