Exogenous surfactant administration by asymmetric high-frequency jet ventilation in experimental respiratory distress syndrome.

AIM: To evaluate the efficacy of surfactant administration using the instillation technique by means of asymmetric high-frequency jet ventilation (HFJV). METHODS: Experiments were carried out on tracheotomized, anaesthetized, and paralyzed rabbits. Animals were lung-lavaged with saline and conventionally ventilated with 100% oxygen. After respiratory failure, they were ventilated for additional 2 hours with conventional ventilation (f=30/min) or HFJV (f=300/min). Subgroups were treated with porcine surfactant (Curosurf; 80 mg/mL, dose 200 mg/kg) as a bolus followed by conventional ventilation or instilled into the jet of the ventilator during asymmetric HFJV (inspiration time Ti=30%). In controls, no material was instilled. RESULTS: Bolus administration of Curosurf followed by conventional ventilation in comparison with conventionally ventilated animals without surfactant improved gas exchange (at 60 minutes: PaO(2)/FiO(2), 9.8-/+3.6 vs 22.3-/+8.5 kPa, P=0.020), reduced right-to-left pulmonary shunts (at 60 minutes: 47.8-/+13.8 vs 23.9-/+6.7 %, P<0.006), and reduced inflammatory response in the lungs. Surfactant administration by HFJV in comparison with bolus instillation resulted in even better gas exchange (at 90 minutes: 20.7-/+8.8 vs 39.1-/+10.9 kPa, P=0.005) and reduction of right-to-left pulmonary shunts (at 90 minutes: 29.1-/+7.2 vs 8.0-/+2.2 %, P=0.008). High-frequency jet ventilation with or without surfactant treatment significantly increased pressure-volume recordings and reduced intraalveolar edema in comparison with conventional ventilation-only group. There were no significant differences in inflammatory response between the two tested methods. CONCLUSION: The response to surfactant therapy in experimental lung injury depends on the surfactant delivery method and may be potentiated by high-frequency jet ventilation.

Treatment of experimental meconium aspiration syndrome with surfactant lung lavage and conventional vs. asymmetric high-frequency jet ventilation.

Respiratory failure caused by meconium aspiration requires combined strategies. We hypothesized that surfactant lung lavage with asymmetric high-frequency jet ventilation (AHFJV) can increase the removal of meconium and improve lung function. During conventional ventilation (CV), a suspension of human meconium (25 mg/ml, 4 ml/kg) was instilled into the tracheal tube of anesthetized rabbits to cause respiratory failure. Animals were then divided into four groups: saline lavage + CV (Sal-CV), surfactant lavage + CV (Surf-CV), saline lavage + HFJV (Sal-HFJV), and surfactant lavage + HFJV (Surf-HFJV). Lung lavage (10 ml/kg in 3 portions) was performed with diluted surfactant (Curosurf, 100 mg of phospholipids/kg) or saline during CV (frequency (f), 30/min; inspiration time (Ti), 50%) or AHFJV (f, 300/min; Ti, 70%). Animals were ventilated for an additional hour with either CV or HFJV (Ti, 50%). Surfactant lavage with both CV and AHFJV removed more meconium than saline lavage. However, the highest removal was found in the Surf-HFJV group vs. all other groups (P < 0.05). The oxygenation index decreased after surfactant lavage in both groups compared to controls (P < 0.001), and more prominently in the Surf-CV group. Elimination of CO(2) was significantly higher in the Surf-HFJV group vs. all other groups (P < 0.05). The ventilation efficiency index increased after lavage in both surfactant groups vs. saline controls (P < 0.05). Dynamic lung-thorax compliance gradually increased, and right-to-left pulmonary shunts decreased in both surfactant groups vs. saline controls after lavage (P < 0.05). Combination of surfactant lavage with both CV and AHFJV was beneficial in rabbits with meconium aspiration syndrome. While AHFJV was more effective in the removal of meconium, CV had a more favorable effect on lung function in the postlavage period.