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Can spontaneous breathing trials help assess extubation readiness in extremely preterm neonates

Despite ongoing medical advances, extremely premature infants continue to have substantial morbidities and mortality. Prolonged mechanical ventilation has been associated with bronchopulmonary dysplasia and neurodevelopmental delays1,2 and is a major reflection of increased healthcare costs.3 Rate of extubation failure in preterm infants is 40– 50%, and many providers strive to find the appropriate time for extubation since reintubation attempts are associated with increased mortality and worsening of respiratory status, along with risks for severe intracranial bleed.4,5 Extubation readiness is primarily steered by clinical judgement and is supported by measures like spontaneous breathing trials (SBT), minute ventilation tests and the extubation predictor calculator.6,7 In neonates, even though SBT is a common practice, success of its applicability is debated. Selection of ‘extubation ready’ candidates for SBT using clinical judgement leads to inherent testreferral bias that overvalues sensitivity and misjudges diagnostic accuracy. Historically, SBT practice is not standardized for its duration and provision of level of support, which may greatly influence the outcomes.8 This report, performed as a secondary analysis to the APEX study, used a recent approach of SBT with ETCPAP of 5– 6 cm H2O for 5 min just prior to extubation. Failed outcome was defined as the need for reintubation within 7 days.9 Similar to prior studies, the successful extubation group had higher gestational age, birthweight, postmenstrual age and lower preextubation oxygen requirement. Also, the successful extubation group compared to the failure group had fewer clinical events during ETCPAP (51% vs 72%) and had less incidence of early termination of SBT (3% vs 20%). This is a unique study where ETCPAP clinical events are described as independent predictors for successful extubation, to bridge the knowledge gap about SBT. None of >41,000 combinations had superior predictive accuracy for successful extubation without high falsepositive rates. Apnea with 15% increase in baseline oxygen had the highest Youdon index of only 0.32 (sensitivity 93%; specificity 39%). Another major strength is the large number of subjects (n = 259) in a multicentre trial. Unlike other studies, there were no preset criteria to extubate, but all subjects got extubated. Additional analyses were performed to overcome potential biases from variations in the observation window from time of extubation and higher and lower gestational ages of the neonates. As a major limitation, the study does not account for clinical judgement selection bias where only those neonates who are ‘ready for extubation’ underwent SBT. A more appropriate design would be diagnostic randomized controlled trial where intubated neonates are randomized to be or not to be assessed by SBT at predetermined intervals. This will be of more clinical relevance and provide robust data on important clinical outcomes. In neonates, a major factor to failed extubation not accounted for could be the interval of time on PEEP support while ETCPAP is administered. SBT does not have consistent criteria to define outcomes and adds little value to safe and reliable decisionmaking. SBT tests do not identify clinically ‘not ready’ neonates and do not apply independently in the absence of clinical judgement. Prospectively, a study to include outcome data of unsuccessful extubation would help in better understanding of SBT failed attempts. The study uses automated algorithmic approach to identify clinical events to predict successful extubation. Alternatively, Bayesian approach incorporating prior probability of extubation success based on weight, gestation etc., can be used to assess the same.