Furthermore, we excluded patients showing signs of paradoxical abdominal movement or use of accessory inspiratory muscles. Exclusion criteria were: contraindications to the insertion of an electrical activity of the diaphragm (EAdi) catheter (e.g., upper gastrointestinal surgery, esophageal varices, esophageal trauma) cardiopulmonary instability, concomitant neuro-muscular pathologies and/or known phrenic nerve dysfunction. Inclusion criteria were age ≥ 18 and a diagnosis of prolonged weaning according to WIND study (i.e., patients not weaned after more than 7 days from the first separation attempt). Patients admitted to the intensive care unit (ICU) of the Bari University Hospital (Italy) between June 2017 and May 2018, requiring mechanical ventilation via tracheostomy, were screened for inclusion in the study. After disconnection from the ventilator, each patient received two 1-h periods of T-HF (T-HF1 and T-HF2) alternated with 1 h of conventional O 2. This was a single-center, unblinded, cross-over study of ventilated patients via tracheostomy with prolonged weaning from mechanical ventilation. Our study hypothesis was that T-HF, compared to conventional O 2, would decrease the neuro-ventilatory drive, work of breathing, respiratory rate and improve gas exchange, in a mixed population of tracheostomized patients at high risk of weaning failure. However, T-HF is a novel therapy and it is not known whether it replicates the physiological advantages of HFNC. Since HFNC decreases the risk of re-intubation in patients at risk of extubation failure, it is reasonable to hypothesize that T-HF could aid the separation from mechanical ventilation in mechanically ventilated, tracheostomized patients at high risk of weaning failure. High-flow oxygen therapy can also be applied to the tracheostomy opening (T-HF) in tracheostomized patients. The synergistic combination of these mechanisms leads to improved oxygenation, decrease in neuro-ventilatory drive and work of breathing. Further, the humidified and warmed gas mixture favors the mucociliary function and reduces upper airway resistance. Compared with conventional oxygen therapy (conventional O 2), HFNC produces several physiological effects, which include: a better matching between the delivered gas flow mixture and patient’s spontaneous inspiratory flow a positive end-expiratory pressure (PEEP) effect (generally between 2 and 8 cm H 2O ) and a “CO 2 wash out” effect from the upper airways. HFNC is increasingly used in several clinical contexts, particularly in de novo hypoxemic respiratory failure post-extubation and in post-cardiothoracic surgery. High-flow nasal cannula oxygen therapy is the administration of a warmed and humidified air/oxygen mixture at a flow rate between 20 and 60 L/min through nasal cannulae (HFNC). The present findings might suggest that physiological effects of high-flow therapy through tracheostomy substantially differ from nasal high flow. In tracheostomized patients at high risk of weaning failure from mechanical ventilation, T-HF did not improve neuro-ventilatory drive, work of breathing, respiratory rate and gas exchange compared with conventional O 2 after disconnection from the ventilator. Similarly, PTP musc/b and PTP musc/min, RR and gas exchange remained unchanged.
We recorded neuro-ventilatory drive (electrical diaphragmatic activity, EAdi), work of breathing (inspiratory muscular pressure–time product per breath and per minute, PTP musc/b and PTP musc/min, respectively) respiratory rate and arterial blood gases.
The inspiratory oxygen fraction was titrated to achieve an arterial O 2 saturation target of 94–98% (88–92% in COPD patients). This was a single-center, unblinded, cross-over study on fourteen patients. In this study, we compared the effects of T-HF or conventional low-flow oxygen therapy (conventional O 2) on neuro-ventilatory drive, work of breathing, respiratory rate (RR) and gas exchange, in a mixed population of tracheostomized patients at high risk of weaning failure. Little is known of the physiological effects of high-flow oxygen therapy applied to the tracheostomy cannula (T-HF). High-flow oxygen therapy delivered through nasal cannulae improves oxygenation and decreases work of breathing in critically ill patients.
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