P0714 - Bedside Lung Ultrasound as a predictor of the extubation readiness in preterm infants

An accurate assessment of extubation readiness in preterm infants is very important as this population is prone to the re-intubation. Current criteria for extubation are based on clinical evaluation, chest radiograph findings, amount of ventilatory support and arterial blood gas (ABG) parameters. Several studies have shown that a low lung volume and/or features of atelectasis extubation could predict extubation failure. Lung ultrasound (LUS) provides with opportunity to detect both alveolar (consolidation) and interstitial lungs diseases at the bed-side. These data combined with clinical information could be used for the prognosis of successful extubation in premature infants.
Study question:
Does lung ultrasonography predict the successful extubation in preterm ventilated infants?
Study hypothesis:
We test the hypothesis that assessment of lung aeration before extubation by bedside LUS could predict extubation success in preterm ventilated neonates.
Study design
It is a prospective observational study conducted at the NICU of Jim Pattison Children’ Hospital, Royal University Hospital.
Inclusion criteria
Invasively ventilated infants born at < 32 weeks of gestational age were included at the time of their first extubation.
Sample size:
A convenience sample: 25 infants
Primary outcome: re-intubation within 12, 36 or 72 hours

Method:
LUS was performed 30 minutes prior to the planned extubation with a longitudinal approach in three standard zones bilaterally (R1, R2 and R3 on the right; L1, L2 and L3 on the left). The ultrasound total execution cut-off time was less than 5 minutes. LUS indexes used for the assessment: A-lines, B-lines, lung collapse/consolidation, bilateral white lungs. The A-lines were used to evaluate the expression of normal alveolar air; B-lines were used for assessment of interstitial syndrome. Lung consolidation was assessed by presence of fractal and tissue-like sign.
Extubation readiness score (ERS) was calculated based on LUS findings by two-independent reviewers.
We used a 12-point system for evaluation of lung aeration (Open lung 0-points, partially open lung 1-point, and collapsed lung 2-point) in each scanned zone. Minimal possible score was 0 points when both lungs appeared well aerated in all three zones, and maximal score of 12 for bilateral lung collapse.

Results:
4 out of 25 infants required re-intubation within 36 hours. While clinical evaluation and amount of respiratory support was similar among all infants, ERSs for infants who required re-intubation were significantly higher (6-9) compare to the rest of the group. Infants with ERSs of 6-8 remained extubated for more than 36 hours, however they required higher CPAP pressures than infants with higher scores.

Conclusions:
Pre-extubation lung ultrasound is a reliable tool to evaluate extubation readiness in preterm infants. ERS of <6 was associated with less risks of re-intubation and lower post-extubation respiratory support.