Effect of Parallel Oxygen Delivery Through a Tracheal Gas Insufflation (TGI) and a T-piece, on Blood Gases and Respiratory Rate, in ICU Tracheostomized Patients

The tracheal insufflation (TGI) of respiratory gasses near to carina is a technique who designed for the removement of exhaled carbon dioxide from the dead space of the lung. In order to investigate the utility of this technique on weaning of mechanical ventilation 11 tracheostomized patients on T-piece were recruited, with stable blood gasses more than 24 hours.

A TGI catheter enters the trachea through a new opened hole on the top of T-piece and then passes through the tracheostomy tube to inside of the trachea and then stops one centimeter before the carina. Patients received two parallel administered respiratory gases with the same fraction of inspired oxygen (FiO2), through a T-piece and an endotracheal catheter, with flows 6 Liters Per Minute (L/min) and 11 L/min, while continuously monitored by impedance tomography device (ΕΙΤ). ΕΙΤ is a noninvasive imaging technique for monitoring in real time the lung volumes and the regional lung ventilation without ionizing radiation.

The basic hypothesis of the study is if there are benefits (better oxygenation, minimized work of breath) from the parallel oxygenation with Tracheal Gas Insufflation and T-piece, in order to provide respiratory support in tracheostomized patients and avoid mechanical ventilation.

The randomization of the study was achieved using sealed envelopes method and associated with the flow to be first (6L/min or 11L/min) via Tracheal Gas Insufflation Catheter (6 envelopes with the inscription 6 L/min on the inner side and 6 envelopes with the inscription 6 L/min on the inner side 11 L/min)

Τhe investigators tested the differences on partial pressure of oxygen (PaO2), respiratory rate and end expiratory impedance:

• Before gasses supply via TGI
• During 6L/min
• During 11L/min
• And finally with no gasses supply via TGI

Additionally the following were monitored:

• Heart rate
• Systolic and diastolic blood pressure
• Oxygen saturation as disturbing factors and,
• potential of hydrogen (pH)
• PaCO2
• hydrogen carbonate (-HCO3) for the monitoring of the acid-base balance of the patient during procedure.

Inclusion criteria

• Tracheostomized haemodynamically stable patients, without the need of vasopressors or inotrope medications, without symptoms of pulmonary edema, or interstitial lung diseases.

Stable blood gasses (no bigger changes than 15-20% in Oxygen and Carbon dioxide during last 24 hours)

Exclusion criteria

• Peripheral body temperature < 38 C, White blood cells (WBCs) < 15 x 109/L
• Respiratory rate >35
• Paradoxical breathing
• Abdominal muscle recruitment
• Dyspnoea, SaO2 < 94, without evidence of angina, cyanosis or arrhythmia.
• Chest circumferences no bigger than 110 cm (for the larger belt of impedance tomograph)