Combined effects of high-frequency ventilation and surfactant treatment in experimental meconium aspiration syndrome.

Abstract

BACKGROUND:

Deterioration of lung function in meconium aspiration syndrome may in part be due to inactivation of endogenous surfactant. We evaluated the efficacy of high-frequency ventilation (HFV) and the combination of HFV and surfactant therapy in the management of respiratory failure induced by experimental meconium aspiration in adult rats.

METHODS:

Animals were anesthetized and tracheotomized, and received via the tracheal cannula a suspension of human meconium (25 mg/ml, dose 4 or 5 ml/kg). After 30 min of conventional ventilation (CV) with 100% oxygen, animals were in respiratory failure as indicated by a decrease in lung-thorax compliance of > or = 30% and PaO2 < 10 kPa. They were then ventilated for an additional 3 h with either CV (frequency 40/min, inspiration time 50%) or HFV (frequency 15 Hz, inspiration time 50%) using comparable mean airway pressures (about 20 cmH2O) and variable FiO2. Subgroups of animals were treated with Curosurf (80 mg/ml, dose 200 mg/kg) 30 min after meconium aspiration; no additional material was instilled in controls.

RESULTS:

From 30 min onwards, values for PaO2/FiO2 were significantly higher in animals ventilated with HFV without receiving surfactant than in control animals subjected to CV alone (at 120 min; 18 +/- 7.3 vs. 7.4 +/- 0.8 kPa, P < 0.05). Additional improvement in oxygenation was seen in HFV-treated animals receiving Curosurf (at 120 min: 39 +/- 16 kPa: P vs. HFV alone < 0.01). Relative lung volumes at a deflation pressure of 10 cmH2O, expressed as percent of maximum volume, were larger in animals ventilated with HFV than in those undergoing CV (41 +/- 12 vs. 33 +/- 10%; P < 0.05), and were further increased in the groups of animals treated with surfactant and ventilated with HFV (55 +/- 9.9%; P vs. animals ventilated with HFV not receiving surfactant < 0.01) or CV (49 +/- 9.6%; P vs. animals ventilated with CV without receiving surfactant < 0.05). Hyaline membranes, granulocytes in cytospin preparations from lung lavage fluid, and vascular-to-alveolar leak of albumin were less prominent in the HFV than in the CV group, particularly in animals treated with surfactant.

CONCLUSION:

Our data indicate that HFV, especially in combination with surfactant therapy, may be superior to CV for treatment of respiratory failure in this animal model of meconium aspiration syndrome.

• Authors: A Calkovska, B Sun, T Curstedt, G Renheim, B Robertson
• Journal: Acta anaesthesiologica Scandinavica (Acta Anaesthesiol Scand) Vol. 43 Issue 2 Pg. 135-45 (Feb 1999) ISSN: 0001-5172 [Print] England
• PMID: 10027019 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Proteins
• Pulmonary Surfactants

Topics

• Air Pressure
• Animals
• Blood Gas Analysis
• Bronchoalveolar Lavage Fluid
• Combined Modality Therapy
• Female
• High-Frequency Ventilation
• Humans
• Infant, Newborn
• Lung (pathology)
• Male
• Meconium Aspiration Syndrome (drug therapy, pathology, therapy)
• Proteins (metabolism)
• Pulmonary Surfactants (therapeutic use)
• Rats
• Rats, Sprague-Dawley
• Respiration, Artificial
• Respiratory Function Tests
• Swine