Intratracheal pulmonary ventilation provides effective ventilation in a near-drowning model

Overdistension of the lungs from high inspiratory pressure is increasingly recognized as a major contributor to lung injury and worsening respiratory failure in the child who requires prolonged mechanical ventilation. Many modes of ventilation (such as high-frequency ventilation) have been introduced in an attempt to decrease this lung injury. Recently, a new mode of tracheal ventilation, intratracheal pulmonary ventilation (ITPV), has been described. By using a catheter positioned at the carina with continuous gas flow, it is possible to achieve effective ventilation at very low pressures. The purpose of this study was to evaluate the usefulness of ITPV in a near-drowning model. Ten domestic Yorkshire swine underwent arterial, venous, and pulmonary arterial catheter as well as tracheotomy placement. All animals received 13 mL/kg of fresh water intratracheally to induce a pulmonary injury. Six pigs were ventilated for 4 hours using ITPV; the other four pigs received conventional mechanical ventilation (CMV). Circulatory and ventilatory pressures, hemodynamic variables, arterial blood gases, and end-tidal CO2 were measured before lung injury and every 30 minutes thereafter. Both proximal and distal peak and mean airway pressures were measured. The animals were ventilated as needed to maintain the arterial blood gases in the normal range. The authors found the expected changes in pulmonary compliance, oxygen requirement, and airway pressure after inducement of lung injury. The six animals treated with ITPV had significantly lower airway pressures than those of controls. Peak inspiratory pressures with ITPV were 8.2 +/- 1.9 cm H2O versus 17.8 +/- 3.7 with CMV (P < .001). Distal mean airway pressures using ITPV were 2.3 +/- 0.1 cm H2O versus 9.0 +/- 3.2 with CMV (P < .01). With respect to hemodynamic variables, there were no differences between experimental and control animals. In conclusion, ITPV can afford effective ventilation in a near-drowning model of lung injury at airway pressures significantly lower than those required with CMV. ITPV could be a very valuable addition to the currently available methods of mechanical ventilation.