Decreased lung injury after surfactant in piglets treated with continuous positive airway pressure or synchronized intermittent mandatory ventilation.
BACKGROUND
Treatment with surfactant (S) decreases lung injury in paralyzed, mechanically ventilated animals. The use of nasal continuous positive airway pressure (CPAP) as an alternative to mechanical ventilation may further improve acute pulmonary outcomes.


OBJECTIVE
To evaluate the effect of surfactant (+S, -S) and synchronized intermittent mandatory ventilation (SIMV) on lung morphology and inflammatory markers in 24 spontaneously breathing piglets treated with CPAP or SIMV after saline lavage-induced lung injury.


METHODS
After induction of lung injury, animals were randomized to CPAP-S, CPAP+S or SIMV+S and treated for 4 h. Physiologic parameters were continuously monitored. After treatment, animals were euthanized and lungs fixed. Bronchoalveolar lavage (BAL) samples were collected for neutrophil count and H(2)O(2).


RESULTS
No physiologic differences were noted. BAL fluid from CPAP-S animals contained more neutrophils and more neutrophil H(2)O(2) than fluid from the SIMV+S or CPAP+S groups (p < 0.05 or greater). Pathologic injury scores were higher in dependent lung regions from CPAP groups (p < 0.05). Injury pattern scores showed greater dependent alveolar inflammation in all (p < 0.02), with more dependent atelectasis in the CPAP groups (p < 0.01). Morphometrics showed less total open alveolar air space in nondependent regions of the SIMV+S group compared to CPAP groups (p < 0.001). Dependent regions showed less total open alveolar air space compared to nondependent regions in the CPAP groups (p < 0.001).


CONCLUSIONS
Animals treated with surfactant prior to CPAP or SIMV had less acute lung injury. SIMV+S animals had less open air space in nondependent regions. This suggests, during early ventilatory support, surfactant administration may modulate pulmonary inflammation. CPAP alone without surfactant may not provide optimal pulmonary protection. The addition of mechanical breaths may alter and add to injury.
Nold
Joan L
JL
Infant Pulmonary Research Center, Children's Hospitals and Clinics of Minnesota, St. Paul, MN 55102, USA.
Meyers
Pat A
PA
Worwa
Cathy T
CT
Goertz
Ronald H
RH
Huseby
Krysta
K
Schauer
Galen
G
Mammel
Mark C
MC
D000818:Animals; D001992:Bronchoalveolar Lavage Fluid; D045422:Continuous Positive Airway Pressure / Q000379:methods*; D004195:Disease Models, Animal; D007385:Intermittent Positive-Pressure Ventilation / Q000379:methods*; D009504:Neutrophils / Q000473:pathology; D011663:Pulmonary Surfactants / Q000627:therapeutic use*; D011897:Random Allocation; D012128:Respiratory Distress Syndrome / Q000139:chemically induced / Q000473:pathology / Q000628:therapy*; D012965:Sodium Chloride; D013552:Swine
D011663:Pulmonary Surfactants; D012965:Sodium Chloride