Prediction of extubation outcome in neonates born prematurely or at term

Abstract

Background: Extubation success depends on the adequacy of respiratory drive, the capacity of the respiratory muscles and the load placed upon them. The tension time index of the diaphragm (TTdi) is a measure of the capacity and load on the diaphragm and TTmus, a non-invasive tension time index of the respiratory muscles. In children, a TTdi of less than 0.15 and a TTmus of less than 0.18 were 100% sensitive and specific in predicting extubation success and, in a pilot study, were reliable predictors in neonates.

Objectives: To determine whether TTdi of less than 0.15 and TTmus of less than 0.18 performed similarly in infants born prematurely and in infants born at term in predicting extubation success.

Methods: Infants were studied within six hours of extubation. TTdi was derived from measurements of trans diaphragmatic pressure using a dual-pressure transducer tipped catheter. TTmus was derived from airway pressure measurements from a side port on a pneumotachograph. Extubation failure was a need for reintubation and ventilation within 48 hours of extubation.

Results: To date, 44 infants (27 born prematurely) with a median gestational age of 33 (range 23-42) weeks and a median birth weight of 1900 (range 464-4536) grams have been studied. Overall eleven infants failed extubation, their median TTdi (p=0.002) and TTmus (p=0.031) were higher than those successfully extubated. A TTdi of less than 0.15 and a TTmus of less than 0.18 were both 94% sensitive in the term born infants but both only 72% sensitive in the prematurely born infants.

Conclusions These results suggest that invasive and non-invasive measurements of TTI may be useful in predicting extubation success in term born but not prematurely born infants.