2006 OPEN FORUM Abstracts
IMPROVED VENTILATION IN PIGLETS TREATED WITH NASAL INTERMITTENT POSITIVE PRESSURE VENTILATION VERSUS SYNCHRONIZED INTERMITTENT MANDATORY VENTILATION
Patricia Meyers, RRT, AL Lampland MD, CT Worwa, RRT,
EC Swanson, MC Mammel MD. Infant Diagnostics & Research Center, Children's
Hospitals & Clinics of Minnesota and Department Of Pediatrics, University
of Minnesota.
Background: Nasal
intermittent positive pressure ventilation (NIPPV) is used to augment
continuous positive airway pressure but there is little information regarding
its efficacy.
Hypothesis: Surfactant
deficient piglets treated with NIPPV would have improved physiologic tolerance
of non-invasive assisted ventilation and decreased inflammatory markers than
those treated with synchronized intermittent mandatory ventilation (SIMV).
Methods: Two modes of assisted
ventilation, NIPPV and SIMV, were compared in spontaneously breathing piglets
with saline lavage induced lung injury (PaO2 <100 torr in FiO2 1.0 for
minimum of 15 minutes). Both modes were provided using the Dräger Babylog 8000.
Animals were randomized to NIPPV (n=12) or SIMV (n=11) and were treated for six
hours. SIMV settings were VT 8ml/kg, PEEP 5, and rate 20. NIPPV settings were PIP 30, PEEP 5, and rate
20. Oxygen was adjusted to maintain PaO2 of 80-100 torr; PIP and rate were
adjusted to alter PaCO2. Physiologic
parameters and arterial blood gases were continuously monitored. Data were recorded prior to lung injury, once
lung injury was achieved, and then hourly. After six hours of treatment,
piglets were euthanized. Lung tissue was then obtained to analyze for evidence
of lung inflammation, including myeloperoxidase, Interleukin 8, and hydrogen
peroxide levels. Inflammatory marker data were analyzed using the
Kruskal-Wallis test. Physiologic data were analyzed using ANOVA.
Results: Piglets treated with SIMV had
increased interstitial inflammation (p<0.05) compared to those treated with
NIPPV. Inflammatory marker levels were
not significantly different between the two groups. Piglets treated with NIPPV
demonstrated improved arterial blood gas pH (p<0.001), improved PaCO2
(p=0.05), and a lower set respiratory rate (p<0.0001) as compared to the
SIMV-treated piglets. Total respiratory rate was not different. However, the
SIMV group had a lower PIP (p<0.001) and improved a-A gradient (p<0.001)
when compared to the NIPPV group. Heart rate, mean blood pressure, and mean
airway pressure were not significantly different between the groups.
Conclusion: Surfactant deficient piglets treated with NIPPV demonstrated less
interstitial lung inflammation and more efficient gas exchange with
proportionally fewer mechanical breaths than those piglets treated with
conventional mechanical ventilation. In surfactant deficient piglets, NIPPV
offers an adequate and non-invasive ventilatory strategy.