HIGH-FREQUENCY PRESSURE-CONTROL VENTILATION WITH HIGH POSITIVE END-EXPIRATORY PRESSURE IN CHILDREN WITH ACUTE RESPIRATORY-DISTRESS SYNDROME

Objective: Animal models suggest that high-frequency ventilation with low tidal volumes and high positive end-expiratory pressure (PEEP) min imize secondary injury to the lung. We hypothesized that using ex high -frequency pressure-control mode of ventilation with high PEEP in chil dren with severe acute respiratory distress syndrome (ARDS) would be a ssociated with improved survival. Design: The study was a retrospectiv e and prospective clinical study at a 24-bed tertiary care pediatric c ritical care unit. Fifty-three patients with severe ARDS were studied during a 37-month period, 30 prospectively and 23 retrospectively. Sev ere ARDS was defined as (1) rapid onset of severe bilateral infiltrate s of noncardiac origin, (2) partial pressure of oxygen (arterial)/frac tion of inspired oxygen less than 200 on PEEP of 6 cm H2O or more for 24 hours or longer, and (3) Murray disease severity score greater than 2.5. All patients meeting these criteria underwent ventilation in the pressure-control mode; the protocol for ventilation had the following general guidelines: (1) fraction of inspired oxygen limited to 0.5, ( 2) mean airway pressure titrated with PEEP to maintain arterial partia l pressure of oxygen at 55 mm Hg or greater (7.3 kPa), (3) peak inspir atory pressure minimized to allow hypercapnia (arterial partial pressu re of carbon dioxide, 45 to 60 mm Hg (6.0 to 8.0 kPa)), and (4) ventil ator rates of 40 to 120/min. Percutaneous thoracostomy and mediastinal tubes were placed for treatment of air leak. Results: The survival ra te was 89% (47/53) in children with severe ARDS. Nonsurvivors had sign ificantly higher peak inspiratory pressures (75 vs 40 cm H2O, p = 0.00 06), PEEP (23 vs 17 cm H2O, p = 0.0004), mean airway pressure (40 vs 2 8 cm H2O, p = 0.04), alveolar-arterial oxygen gradient (579 vs 540 mm Hg, p = 0.03), and oxygenation index (43 vs 19, p = 0.0008) than survi vors. Air leak was present in 51% of patients; there was no difference in the incidence of air leak between survivors and nonsurvivors (p = 0.42). Conclusions: The high-frequency positive-pressure mode of venti lation was safe and was associated with an improved survival rate (89% ) for children with severe ARDS. Limitation of both inspired oxygen an d tidal volume, along with aggressive treatment of air leak, may have contributed to the improved survival rate.