Objective To describe the thresholds of instability used by clinicians at reintubation and evaluate the accuracy of different combinations of criteria in predicting reintubation decisions.

Design Secondary analysis using data obtained from the prospective observational Automated Prediction of Extubation Readiness study (NCT01909947) between 2013 and 2018.

Setting Multicentre (three neonatal intensive care units).

Patients Infants with birth weight ≤1250 g, mechanically ventilated and undergoing their first planned extubation were included.

Interventions After extubation, hourly O₂ requirements, blood gas values and occurrence of cardiorespiratory events requiring intervention were recorded for 14 days or until reintubation, whichever came first.

Main outcome measures Thresholds at reintubation were described and grouped into four categories: increased O₂, respiratory acidosis, frequent cardiorespiratory events and severe cardiorespiratory events (requiring positive pressure ventilation). An automated algorithm was used to generate multiple combinations of criteria from the four categories and compute their accuracies in capturing reintubated infants (sensitivity) without including non-reintubated infants (specificity).

Results 55 infants were reintubated (median gestational age 25.2 weeks (IQR 24.5–26.1 weeks), birth weight 750 g (IQR 640–880 g)), with highly variable thresholds at reintubation. After extubation, reintubated infants had significantly greater O₂ needs, lower pH, higher pCO₂ and more frequent and severe cardiorespiratory events compared with non-reintubated infants. After evaluating 123 374 combinations of reintubation criteria, Youden indices ranged from 0 to 0.46, suggesting low accuracy. This was primarily attributable to the poor agreement between clinicians on the number of cardiorespiratory events at which to reintubate.

Conclusions Criteria used for reintubation in clinical practice are highly variable, with no combination accurately predicting the decision to reintubate.