Therapeutic lung lavage in Meconium Aspiration Syndrome: a preliminary report

Meconium aspiration syndrome (MAS) is an important cause of respiratory failure in the term infant for which there is a frustrating lack of effective therapy. Recently, therapeutic lung lavage has been investigated as a mean of cleaning the lung in ventilated infants with MAS. In animal models, lung lavage has been found to be effective in clearing meconium from the lung, and thereby to produce improvements in oxygenation, lung mechanics and degree of lung injury. Additionally, dilute surfactant has been found to be a more effective lavage fluid than saline. In human infants the available data consist of a number of case series and two small randomised controlled trials. These investigations have suggested that lavage therapy may have a place in the management of MAS, although the lavage protocols used have been disparate.
In this study, an initial experience of lung lavage in human infants with severe MAS is reported, describing physiological data related to the safety of lavage with different volumes and comparing short-term outcomes with those of ventilated infants with MAS who did not receive lavage. Infants with severe MAS, requiring high-frequency ventilation, underwent lung lavage using dilute bovine surfactant (phospholipid concentration of 5 mg/mL). Lavage aliquot volumes were increased through the case series, aiming to deliver two aliquots of 15 mL/kg in rapid sequence.
In total, nine episodes of lavage were performed in eight infants at a median age of 23 hours (range 8-83 h). Three infants underwent a lavage that was defined as potentially therapeutic (total lavage volume of at least 25 mL/kg administered before 24 h of age). Lavage was not associated with bradycardia or hypotension. Recovery of arterial oxygen saturation to above 80% was achieved within 12 min in all but one infant in whom oxygen saturation was below 80% at the outset. Mean airway pressure was significantly lower in the therapeutic lavage group compared with non-lavage group in the first 48 h, with a trend towards improved oxygenation.
This preliminarily report documents the feasibility of large volume therapeutic lung lavage in ventilated infants with MAS. Even in the setting of severe parenchymal disease with concomitant pulmonary hypertension, lavage was well tolerated, causing transient oxygen desaturation but minimal disturbance to pH, base excess or PaCO2. Moreover, there was evidence that early lavage with large volumes of fluid (i.e. a potentially therapeutic lavage) was associated with more rapid weaning of ventilator pressure, and better oxygenation in the first 48 h of hospitalisation, albeit compared with a nonrandomised MAS control group selected only on the basis of need for high-frequency ventilation.
In conclusion, this preliminary experience suggests that lung lavage with two aliquots of up to 15 mL/kg of dilute surfactant is feasible in haemodynamically stable ventilated infants with MAS. Further investigation of this method of lavage in a randomised controlled trial is essential to fully understand the value of this therapeutic approach.

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