Comparison of the Clinical Effects of the Different Ventilatory Care Strategies in the Neonates with Acute Respiratory Failure: High Flow Rate - Constant Flow Rate

ABSTRACT

PURPOSE: High flow rate (FR) and pressure limit (PL) strategy with time-cycled pressure-limited (TCPL) ventilator is employed routinely in the neonates. Theoretical basis of this strategy is the two-compartment theory that the lung with acute respiratory failure consists of units with different compliance and resistance. But such constant pressure strategy has the risk of ventilator induced lung injury. We compared the ventilatory indices and clinical outcomes of two different strategies, high FR-constant pressure and low FR-constant FR in the ventilator care of the neonates with acute respiratory failure. METHODS: For the neonates born in our hospital and treated with mechanical ventilation from March to August in 1997, two different ventilator strategies were employed randomly with flow control ventilator. In the high-FR group, the FR was fixed at 10 L/ min and the PL was adjusted according to the arterial blood gas analysis (ABGA) results. In the low-FR group, the FR was adjusted to 10 mL/kg of tidal volume. Sixty neonates were enrolled, 32 in high-FR and 28 in low-FR group. Ventilatory indices and clinical outcomes were statistically cornpared in the two groups. RESULTS: Perinatal factors were not different in the two groups. Initial ventilator settings, ABGA results and ventilatory indices were not different. The tidal volume, fraction of inspired oxygen, peak inspired pressure and oxygenation index were higher and dynamic compliance was lower in the high-FR group compared to the low-FR group after 3 to 72 hours of ventilator care. In clinical outcomes, incidences of pulmonary interstitial emphysema, pneumothorax and chronic lung disease were significantly lower in the low-FR group. CONCLUSION: Low-FR with constant FR strategy resulted in better clinical outcomes in the ventilator care of neonates. We conclude that constant FR strategy prevents damage of the better compliant lung units and decreases the incidence of acute and chronic complications of ventilator care.