Inadequate lung volume recruitment after sustained lung inflation
in high frequency oscillatory ventilation: Pathophysiology and inflammation in
an animal RDS model
Affiliations: Eastern Maine Medical Center, Bangor, ME 04401,
USA | Infant Pulmonary Research Center, Children's Hospitals
and Clinics, St. Paul, Minnesota, MN 55102, USA | Kaiser Permanente, Department of Pathology, Oakland
Medical Center, Oakland, CA 94611, USA | Departments of Pediatrics, University of Minnesota,
Minneapolis, MN 55102, USA
Note: [] Corresponding author: Mark C. Mammel, MD, Infant Diagnostic and
Research Center, Children's Health Care-St. Paul, 347 North Smith Avenue, Room
505, St. Paul, MN 55102, USA. Tel.: +1 651 220 6261; Fax: +1 651 220 7777;
E-mail: mamme001@tc.umn.edu
Abstract: Objective: We hypothesized that a single sustained inflation (SI) of
the lung as a volume recruitment maneuver during high frequency oscillatory
ventilation (HFO-SI) would improve pathophysiologic, inflammatory responses
when compared to conventional inflation (CI) during both HFO (HFO-CI), volume
targeted synchronized intermittent mandatory ventilation (SIMV+V) in
spontaneously breathing newborn piglets with surfactant washout. Design:
Prospective, randomized animal study. Subjects: Thirty-two newborn piglets. Interventions: Animals underwent saline lavage to produce lung
injury, received surfactant and randomized to one of 3 treatment groups. Lung
volume recruitment (LVR) protocol followed and ventilation continued for 6
hours. Measurements and main results: Vital signs and arterial blood
gases were continuously monitored. End expiratory lung volume (ΔEELV)
changes were estimated during LVR using respiratory impedance plethysmography
(RIP). At baseline, post lung injury, 6 hours: serum, bronchoalveolar lavage
(BAL) samples for proinflammatory cytokines were collected and static pressure
volume (P/V) curves obtained. At 6 hours animals were euthanized and lungs
fixed for morphometrics, histopathology. ΔEELV during LVR was greatest
using SIMV+V, HFO-CI (p<0.05); HFO-SI required higher P_{aw} for LVR
compared to SIMV+V (p< 0.005), while ΔEELV change was lowest.
Oxygenation was greatest with SIMV+V. Inflammatory responses, histopathology
and morphometrics were similar. Conclusions: Single SI during HFO is not
adequate for LVR. SIMV+V and HFO-CI adequately recruited lung volumes
without creating more lung injury.
Keywords: High frequency oscillation, mechanical ventilation, respiratory failure, lung injury, lung recruitment maneuver, cytokines
