Weaning from long-term mechanical ventilation: a nonpulmonary weaning index

Despite the extensive investigations in the area of weaning, clinicians are still struggling with the question of when to begin the process of weaning. Clinical weaning indices designed to predict the weaning potential are most frequently based on pulmonary factors. However, many physiological, respiratory, and mechanical factors also have impact on weaning, but are often overlooked. We suggest a new "nonpulmonary weaning index" (NPWI), which assesses the influence of factors such as blood albumin and total blood protein on the weaning success.

We assess the information value of 17 clinical and paraclinical indices in a retrospective study covering 151 patients on a long-term (at least 7 days) mechanical ventilation. The most informative of those 17 indices are used in the formulation of NPWI. Its threshold differentiates the successful from the unsuccessful weaning trials.

From all 17 indices the most significant are: total blood protein, blood albumin, PaO2, hematocrit, lactate, the ratio PaO2/FiO2, hemoglobine, and RUE. The proposed index uses only two of them: blood albumin and total blood protein. It is easily calculated and can easily be tracked in time. It has high sensitivity and specificity.

The results of this study suggest that in the decision whether to attempt weaning from long-term mechanical ventilation, more attention should be paid to the nonpulmonary factors.