Comparison of Physiological Effects of Two Types of High-Flow Oxygen Therapy in Tracheostomized Patients

High-flow nasal oxygen therapy has been shown to provide several physiological benefits, including precise control of the fraction of inspired oxygen, generation of flow-related positive end-expiratory pressure, increased end-expiratory lung volume, improved oxygenation, and enhanced carbon dioxide elimination. It has been widely utilized in managing acute hypoxemic respiratory failure and preventing hypoxemia after extubation.

High-flow oxygen therapy can be applied via tracheostomy as high-flow tracheal oxygen. Previous studies have reported successful cases of using high-flow tracheal oxygen to facilitate weaning from prolonged mechanical ventilation in patients with restrictive and obstructive pulmonary disorders. However, compared to high-flow nasal oxygen, high-flow tracheal oxygen exhibits significantly diminished physiological effects due to the bypassing of the narrow nasopharynx, glottis, and upper airway, as well as a more open circuit.

To address this limitation, the investigators have developed a modified high-flow tracheal oxygen tube with a reduced expiratory end tube diameter. This modification aims to create higher expiratory resistance and airway pressure, thus simulating the physiological effects of high-flow nasal cannula. This is a prospective randomized crossover physiological trial designed to compare the effects of standard and modified high-flow oxygen therapy in tracheostomized patients. Key physiological parameters will be assessed, including airway pressure, end-expiratory lung volume, vital signs, oxygenation, and respiratory workload.

Inclusion criteria

Tracheostomy with stable spontaneous breathing.

Exclusion criteria

• Age younger than 18 years old
• Pregnancy
• Hemodynamic instability (mean arterial pressure <60 mmHg, heart rate >140 or <60 bpm)
• Respiratory and oxygenation instability (respiratory rate > 35bpm or oxygen saturation measured by pulse oximetry <90%)
• Neuromuscular diseases or phrenic nerve injury
• Recent trauma or surgery to the trachea, esophagus, neck, chest, or stomach
• Pneumothorax or placement of a chest drainage
• Contraindication to electrical impedance tomography (EIT) (implantable defibrillator)
• Anticipating withdrawal of life support