Dead space washout by intentional leakage flow during conventional ventilation of premature infants—an experimental study

OBJECTIVE: Invasive mechanical ventilation poses a strong risk factor for the development of chronic lung disease in preterm infants. A reduction of the dead space as part of the total breathing volume would reduce the ventilation effort and thereby lower the risk of ventilator‐induced lung injuries. In this experimental study, we compared the efficacy of mechanical dead space washout via uncontrolled and controlled leakage flow in their ability to eliminate CO(2) during conventional ventilation in preterm infants. METHODS: Three frequently used neonatal ventilators, operating under standard conventional ventilating parameters, were individually connected to a test lung. To maintain a constant physiological end‐expiratory pCO(2) level during ventilation, the test lung was continuously flooded with CO(2). A side port in the area of the connector between the endotracheal tube and the flow sensor allowed breathing gas to escape passively or in a second experimental setup, regulated by a pump. Measurements of end‐expiratory pCO(2) were taken in both experiments and compared to end‐expiratory pCO(2) levels of ventilation without active dead space leakage. RESULTS: Following dead space washout, a significant reduction of end‐expiratory pCO(2) was attained. Under conditions of uncontrolled leakage, the mean decrease was 14.1% while controlled leakage saw a mean reduction of 16.1%. CONCLUSION: Washout of dead space by way of leakage flow is an effective method to reduce end‐expiratory pCO(2). Both controlled and uncontrolled leakage provide comparable results, but precise regulation of leakage allows for a more stable ventilation by preventing uncontrolled loss of tidal volume during inspiration.