High-frequency oscillatory ventilation with low oscillatory frequency in pulmonary interstitial emphysema.
BACKGROUND
Pulmonary interstitial emphysema (PIE) is a common respiratory illness in preterm infants associated with significant morbidity and mortality for which the ventilatory management is imperfect.


OBJECTIVE
To evaluate the impact of high-frequency oscillatory ventilation (HFOV) with a low oscillatory frequency and thus prolonged expiratory time in preterm infants with severe PIE.


METHODS
In a retrospective cohort study, preterm infants ≤30 weeks' gestation with radiological findings of severe PIE, and either high FiO2 or persistent respiratory acidosis were studied if managed on HFOV with a low frequency (5-6 Hz, inspiratory time 30%) for >24 h. Trends in physiological and ventilatory parameters were examined over the first 72 h, radiological changes noted, and in-hospital outcomes ascertained.


RESULTS
19 cases were identified and analysed in two groups: 14 with bilateral and 5 with predominantly unilateral disease. After transition to low-frequency HFOV, physiological responses were seen in both groups, in particular a rapid and sustained improvement in oxygenation in the bilateral group (mean (SD) alveolar-arterial oxygen difference at baseline: 404 ± 206 mm Hg; 4 h post-transition: 262 ± 181 mm Hg; 72 h: 155 ± 74 mm Hg; p = 0.0003). This occurred following a reduction in mean airway pressure (mean (SD) baseline: 14 ± 3.9 cm H2O; 72 h: 12 ± 2.9 cm H2O; p = 0.011). In the unilateral group, radiological resolution of PIE was observed on re-inflation following collapse of the affected lung. Overall, 15 infants survived, including 10 of the bilateral cases (71%), and all of the unilateral cases.


CONCLUSIONS
HFOV with a low oscillatory frequency may afford benefit in preterm babies with severe PIE.
Neonatal and Paediatric Intensive Care Unit, Royal Hobart Hospital, Hobart, Tas., Australia.
Katharine A G
KA
Squires
Antonio G
AG
De Paoli
Christopher
C
Williams
Peter A
PA
Dargaville
D015331:Cohort Studies; D005260:Female; D006612:High-Frequency Ventilation / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology*; D008168:Lung / Q000000981:diagnostic imaging / Q000503:physiopathology; D017563:Lung Diseases, Interstitial / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D011656:Pulmonary Emphysema / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D011859:Radiography; D012189:Retrospective Studies; D012720:Severity of Illness Index; D015996:Survival Rate; D013997:Time Factors; D016896:Treatment Outcome; D012122:Ventilators, Mechanical