The Timed Inspiratory Effort Index as a Weaning Predictor: Analysis of Intra- and Interobserver Reproducibility

Prolonged ventilatory weaning may expose patients to unnecessary discomfort, increase the risk of complications, and raise the costs of hospital treatment. In this scenario, indexes that reliably predict successful liberation can be helpful.

To evaluate the intra- and interobserver reproducibility of the timed inspiratory effort index as a weaning predictor.

This prospective observational study included subjects judged as able to start liberation from mechanical ventilation. For the intra-observer analysis, the same investigator performed 2 measurements in each selected patient with an interval of 30 min a rest. For interobserver analysis, 2 measurements were obtained in another sample of subjects, also with an interval of 30 min rest, but each of one performed by a different investigator. The Bland-Altman diagram, the coefficient concordance of kappa, and the Pearson correlation coefficient were used to compare the measurements. The performance of the timed inspiratory effort index was assessed by receiver operating characteristic curves. Values of P < .05 were considered significant.

We selected 113 subjects (43 males; mean ± SD age, 77 ± 14 y). Fifty-six (49.6%) achieved successful liberation, and 33 (29%) died in the ICU. The mean ± SD duration of mechanical ventilation was 14.4 ± 6.7 d. The Bland-Altman diagrams that addressed intra- and interobservers agreement showed low variability between measurements. Values of the concordance coefficients of kappa were 0.82 (0.68-0.95) and 0.80 (0.65-0.94), and of the linear correlation coefficients, 0.86 (0.77-0.91) and 0.89 (0.82-0.93) for the intra- and interobservers measurements, respectively. The mean ± SD values for the area under the curve for each pair of the intra- and interobserver measurements were 0.96 ± 0.07 versus 0.94 ± 0.07 (P = .41) and 0.94 ± 0.05 versus 0.90 ± 0.07 (P = .14), respectively.

The variability of the measurement of the timed inspiratory effort index by intra- and interobservers showed very high reproducibility, which reinforced the index as a sensible, accurate, and reliable outcome predictor of liberation from mechanical ventilation.