Background: Adult respiratory distress syndrome develops in up to 20% of patients with severe head injury. This complicates the treatment of head-injured patients because lung-protective strategies such as high positive end-expiratory pressure (PEEP) and permissive hypercapnia may increase intracranial pressure (ICP) and reduce cerebral perfusion pressure. The use of high-frequency percussive ventilation (HFPV) is an alternate mode of ventilation that may improve oxygenation for head-injured patients while also lowering ICP.
Methods: Clinical data were collected retrospectively over a 1-year period. Patients were included if they had a severe traumatic brain injury with a Glasgow Coma Score (GCS) of 8 or lower, a ventriculostomy drain for ICP measurement and cerebral spinal fluid drainage, and adult respiratory distress syndrome. Patients were switched from conventional mechanical ventilation to HFPV at the discretion of the attending trauma surgeon. Data for partial pressure of oxygen to fraction of inspired oxygen (PF) ratio, peak inspiratory pressure (PIP), ICP, partial pressure of carbon dioxide level (PCO2), PEEP, and mean airway pressure were compared before and then 4 and 16 hours after institution of HFPV therapy.
Results: A total of 10 patients met study criteria. Data were expressed as mean +/- standard error. There was an increase in PF ratio (91.8 +/- 13.2 vs. 269.7 +/- 34.6; p < 0.01), PEEP (14 +/- 2.5 vs. 16 +/- 3.5), and mean airway pressure (20.4 +/- 4.8 vs. 23.6 +/- 6.8) 16 hours after institution of HFPV. There was a decrease in ICP (30.9 +/- 3.4 vs. 17.4 +/- 1.7; p < 0.01), PC02 (37.7 +/- 4.1 vs. 32.7 +/- 1.1; p < 0.05), and PIP (49.4 +/- 10 vs. 41 +/- 7.9; p < 0.05) at 16 hours. Overall mortality was 10%.
Conclusions: Therapy with HFPV produced a significant improvement in oxygenation with a concomitant reduction in ICP during the first 16 hours. This therapy may represent an important new method for the management of adult respiratory distress syndrome among head-injured trauma patients, although the long-term outcome of HFPV still needs evaluation.