Comparison of Physiological Effects of Two High-Flow Tracheal Oxygen Versus T-Piece During Spontaneous Breathing Trials

A spontaneous breathing trial (SBT) is a crucial step in the weaning and extubation process for assessing extubation tolerance. However, the optimal approach for conducting SBTs remains a topic of debate.

High-flow nasal oxygen 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. High-flow oxygen therapy can also be applied via an artificial airway as high-flow tracheal oxygen. Previous studies have identified this therapy as a potential alternative for SBTs. 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, thereby simulating the physiological effects of HFNC. This study is a prospective randomized crossover physiological study designed to compare the effects of standard and modified high-flow tracheal oxygen versus T-piece during spontaneous breathing trials. Key physiological parameters will be assessed, including airway pressure, end-expiratory lung volume, vital signs, oxygenation, and respiratory workload.

Inclusion criteria

• Mechanical ventilation for more than 24 hours
• Considered by the physicians for the readiness to wean and ready for spontaneous breathing trials

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