1995 OPEN FORUM Abstracts
TRACHEAL GAS INSUFFLATION: A BRIDGE TO HIGH FREQUENCY VENTILATION.
Hussein N. El-Lessy, RRT, Perinatal/ Pediatric Specialist. James C. Cunningham, MD, Pediatric Pulmonologist. Cook Children's Medical Center, Fort Worth, Texas.
In satisfying targeted parameters, pulmonary integrity is often compromised by high transalveolar pressures provided by conventional ventilation. Tracheal gas insufflation (TGI) provides a solution via a less invasive method of ventilation: dead space ventilation. This is accomplished by the insertion of a flexible catheter into an ET tube. By positioning the mouth of the catheter proximal to the carina and providing a modest flow of equal FiO2 concentration, a jet of gas projects for a sufficient distance past the orifice of the catheter to effect dead space ventilation. During TGI, PaCO2 falls in a direct but non-linear relation to the rate of flow provided through the catheter. Two cases were evaluated for effectiveness. Case 1. An 8.6 kg female presented with aspiration pneumonitis and subsequent RDS. Mechanical ventilation utilizing high rates and high PIPs failed to provide adequate ventilation (pH 7.30, PaCO2 93 torr, and PaO2 64 torr), and hemodynamic stability (pulmonary vascular resistance (PVR) 2020 dynes, mean pulmonary artery pressure (MPAP) 48 torr, and central venous pressure (CVP) 14 torr). Following initiation of TGI at 2 lpm of equal FiO2, ABGs revealed a modest improvement in ventilation (pH 7.34, PaCO2 69 torr, and PaO2 83 torr). Hemodynamic improvements ensued with a 50% reduction in PVR to 1050 dynes, MPAP 34 torr, and CVP 10 torr. Case 2. An 8.6 kg male with bilateral pulmonary transplants presented with respiratory insufficiency of unknown etiology. Conventional ventilation utilizing high rates and high PIPs proved futile in eliminating PaCO2 levels of over 150 torr, pH of 6.90, PaO2 83 torr, PVR of 800 dynes, MPAP of 35 torr, and pulmonary artery wedge pressure (PAWP) of 19 torr. Immediately following initiation of TGI at 2 lpm of equal FiO2, PaCO2 levels plummeted to 64 torr (pH of 7.33, PaO2 of 214 torr, PVR of 695 dynes, MPAP of 23 torr, and PAWP of 11 torr). It is easy to discern the potential for this experimental form of assisted ventilation in the more passive treatment of CO2 retention and pulmonary hypertention.