Difficult extubation in low birthweight infants

Bronchopulmonary dysplasia (BPD) is a common adverse outcome of premature birth, often associated with the requirement of supplemental oxygen at home for many months, frequent readmissions to hospital in the first 2 years of life and long-term lung function abnormalities. Prolonged mechanical ventilation has been identified as a possible risk factor for BPD; therefore, it is desirable to wean low birth weight (LBW) infants from ventilation and extubate them as soon as possible. However, an inappropriate weaning or a premature extubation may result in deterioration. Thus, the identification of optimal respiratory support strategies and effective adjunctive treatments has a central role in facilitating extubation. In this review, the current evidence on these topics are discussed.
The use of respiratory support strategies before and after extubation has been investigated in several trials. Overall, the results of randomized trials indicate that weaning is best accomplished by triggered techniques which support every spontaneous breath, such as assist control ventilation or pressure-support ventilation. For what concerns volume-targeted ventilation (VTV), a meta-analysis of the results of four randomised trials suggested that it may be associated with a significant reduction in the duration of ventilation, even if the trials were of small sample size and of difficult comparison. Nasal continuous positive airways pressure (CPAP) after extubation reduces the incidence of adverse clinical incidents, leading to the need for additional respiratory support. The efficacy of nasal CPAP, however, may depend on the delivery technique and, in general, weaning from CPAP should occur in a timely fashion to avoid facial/nasal trauma. Synchronised nasal intermittent mandatory ventilation (NIMV) may be helpful in infants who fail to be maintained on nasal CPAP alone after extubation, as in randomised trials NIMV compared with CPAP increased successful extubation. NIMV, however, should be used with caution as these studies were of small sample size.
It has been shown that methylxanthines treatment facilitates extubation, reducing significantly the risk of failure. In particular, caffeine with its wider therapeutic margin is the preferred treatment and is associated with a dose-dependent efficacy (high-dose appears to be more effective) and a good tolerability profile.
Another possible approach is based on corticosteroids, which can facilitate weaning regardless of postnatal age at administration. There are concerns, however, about the long-term side effects of corticosteroids. As a consequence, the efficacy of low-dose dexamethasone has been investigated, showing promising results and suggesting the need for further studies. An alternative approach to avoid the side effects of systemic steroids is to use inhaled steroids. A meta-analysis demonstrated that inhaled steroids administered for 1-4 weeks improved extubation rates; the optimal dosing schedule and method of delivery, however, need defining.
Finally, careful assessment of clinical criteria to predict successful extubation and an appropriate decision-making process for play also a role on outcomes.
In conclusion, the approaches described above as appropriately evidence-based should be considered by practitioners for current use to reduce difficult/unsuccessful extubation. However, it must be emphasized that the majority of studies of weaning and extubation have included infants who had respiratory distress syndrome, and future research needs to target specifically the chronically ventilated infant developing, and with, BPD.

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