Measurements of respiratory mechanics in difficult weaning

Introduction

The evaluation of respiratory mechanics through an esophageal balloon can improve the evolution of a difficult weaning.

Method

We originally studied eight patients, and change in medical weaning procedures were evaluated, before and after the respiratory mechanics measurements. Later, the study was modified and another 10 patients were observed according to the modification on clinical diagnosis of the respiratory failure (if the problem was related to compliance, resistance, drive or muscle dysfunction). The agreement among three observers that were asked to make the diagnosis were evaluated, before and after the measurements.

Results

The compliance was reduced in 10 patients (mean 47.72 ± 26.89 ml/cmH₂O); respiratory drive was assessed through the measurement of P0.1 and was increased in two patients and reduced in seven (mean 2.7 ± 3.3 cmH₂O); esophageal pressure was increased in five patients and reduced in two (mean 13.57 ± 10.08 cmH₂O); respiratory work was increased in four patients and reduced in one (mean 1.04 ± 0.56 J/l), both, esophageal pressure and respiratory work was observed only in 10 of the 18 patients; airway resistance was increased in 16 patients (mean 15.34 ± 9.16 cmH₂O/l/s). The mean of respiratory rate (RR)/tidal volume (Vt) index was 123.4 ± 85.4 and was over 105 in eight out of 17 patients. There was difference in clinical diagnosis in 50% of the time, before and after measurements. The changes in clinical diagnosis happened in eight out of 10 patients (P = 0.057) and in weaning procedures in 14 out of 18 patients (P = 0.018). Evolution of weaning was satisfactory in 11 out of 16 patients (P = 0.059).

Conclusion

These results show how important could be the measurements of respiratory mechanics, when the weaning is difficult, modifying the clinical diagnosis as well as the weaning procedures, contributing to a better outcome.