Does taking endurance into account improve the prediction of weaning outcome in mechanically ventilated childrenReport as inadecuate

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Critical Care

, 9:R798

First Online: 16 November 2005Received: 15 July 2005Revised: 12 September 2005Accepted: 11 October 2005


IntroductionWe conducted the present study to determine whether a combination of the mechanical ventilation weaning predictors proposed by the collective Task Force of the American College of Chest Physicians TF and weaning endurance indices enhance prediction of weaning success.

MethodConducted in a tertiary paediatric intensive care unit at a university hospital, this prospective study included 54 children receiving mechanical ventilation ≥6 hours who underwent 57 episodes of weaning. We calculated the indices proposed by the TF spontaneous respiratory rate, paediatric rapid shallow breathing, rapid shallow breathing occlusion pressure ROP and maximal inspiratory pressure during an occlusion test Pimax and weaning endurance indices pressure-time index, tension-time index obtained from P0.1 TTI1 and from airway pressure TTI2 during spontaneous breathing. Performances of each TF index and combinations of them were calculated, and the best single index and combination were identified. Weaning endurance parameters TTI1 and TTI2 were calculated and the best index was determined using a logistic regression model. Regression coefficients were estimated using the maximum likelihood ratio LR method. Hosmer–Lemeshow test was used to estimate goodness-of-fit of the model. An equation was constructed to predict weaning success. Finally, we calculated the performances of combinations of best TF indices and best endurance index.

ResultsThe best single TF index was ROP, the best TF combination was represented by the expression 0.66 × ROP + 0.34 × Pimax, and the best endurance index was the TTI2, although their performance was poor. The best model resulting from the combination of these indices was defined by the following expression: 0.6 × ROP – 0.1 × Pimax + 0.5 × TTI2. This integrated index was a good weaning predictor P < 0.01, with a LR of 6.4 and LR-LR ratio of 12.5. However, at a threshold value <1.3 it was only predictive of weaning success LR = 0.5.

ConclusionThe proposed combined index, incorporating endurance, was of modest value in predicting weaning outcome. This is the first report of the value of endurance parameters in predicting weaning success in children. Currently, clinical judgement associated with spontaneous breathing trials apparently remain superior.

AbbreviationsAUCarea under the curve

FiO2fractional inspired oxygen

LRlikelihood ratio

NPVnegative predictive value

Pimaxmaximal inspiratory pressure during an occlusion test

PRISMPaediatric Risk of Mortality Score

PSVpressure support ventilation

PTIpressure-time index

ROP RSB occlusion pressure

RRrespiratory rate

RSBrapid shallow breathing

SBTspontaneous breathing trial

TFTask Force of the American College of Chest Physicians

Tiinspiratory time

TTItension-time index

Ttottotal respiratory cycle time.

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Author: Odile Noizet - Francis Leclerc - Ahmed Sadik - Bruno Grandbastien - Yvon Riou - Aimée Dorkenoo - Catherine Fourier - Robin


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