Perfluorocarbon broncho-alveolar lavage and liquid ventilation versus saline broncho-alveolar lavage in adult guinea pig experimental model of meconium inhalation.

Abstract

This study compares perfluorocarbon broncho-alveolar lavage (PFC-BAL) with isotonic saline broncho-alveolar lavage (saline-BAL) in an experimental model of meconium aspiration in adult guinea pigs. Prospective controlled experimental study. Ten male guinea pigs were given 1 ml of human meconium, diluted to 10% in isotonic saline, via tracheostomy and then artificially ventilated. After stabilization, five animals (control group) underwent BAL with 10 ml/ kg isotonic saline solution. After bronchial suctioning, a further BAL with 2 ml/kg saline was performed. The other five animals (study group) underwent BAL with 100 ml/kg of PFC (RIMAR 101). Bronchosuction was effected at 5 min and then a BAL with PFC 2 ml/kg was performed. Both groups received conventional mechanical ventilation during the lavage procedures. Within 20 min all the saline-BAL treated animals died, whereas the PFC-BAL treated animals survived and were then treated with total liquid ventilation (TLV) by gravity. After meconium inhalation in both groups, a large alveolar-arterial oxygen difference, hypercarbia, severe acidosis and tachycardia were noticed. In PFC treated animals, an improvement in blood gases was noted and acid-base balance remained stable compared to saline-BAL treated animals. No haemodynamic change was observed during or after PFC-BAL, while during saline-BAL there was evidence of bradycardia, hypotension and respiratory failure, which led to the death of the animals. The histological lung sections in the PFC-BAL group showed evidence of normal alveolar expansion with a minimal presence of meconium debris in the small bronchioles. In saline-BAL treated animals, the lung structure appeared severely compromised with the presence of meconium in bronchioles and alveoli, intra-alveolar oedema and haemorrhagic areas. This study confirms the detrimental effects of meconium aspiration and the impairment of lung function following saline-BAL. By contrast, PFC-BAL and TLV by gravity seemed to prevent absorption of meconium, facilitate its removal, improve gas exchange and reduce lung barotrauma.