© 2007 American Thoracic Society
Computer-driven Protocolized Weaning from Mechanical VentilationFrom the Authors:
We first would like to thank Drs. Kager and Schultz for their interest in our recent article (1). Their first comment concerned the different definitions of the "comfort zone" between the study and control groups. During the weaning process, the target zone for the respiratory rate as indicated in the written guidelines of the different centers slightly differed: 25–35 breaths/min and clinical comfort (Créteil), 25–30 breaths/min and an adequate adaptation to the ventilator (Barcelona), or below 30 breaths/min with a tidal volume The other point raised concerned the tidal volumes used in both arms. We did not record tidal volumes in the two arms after inclusion and cannot fully address this question. At inclusion, tidal volumes were 574 ± 129 ml in the computerized weaning group and 554 ± 142 ml in the control group (p = 0.402). Interestingly, patients could be included who had an SpO2 above or equal to 90% and FIO2 below or equal to 50%. These criteria allowed the inclusion of patients with PaO2 /FIO2 below 200. Interestingly, at inclusion, 15 patients (20.3%) in the computer-driven weaning and 16 patients (22.9%) in the control group (p = 0.706) had a PaO2/FIO2 ratio < 200 mm Hg. This shows that patients with quite low levels of PaO2 /FIO2 can be managed with the system. However, the system should be used in patients who demonstrate improving respiratory condition, with stable hemodynamic and neurological status, and not at the time a patient is developing ARDS. In particular, the sytem is not designed to maintain tidal volume at a fixed level.
Hôpital Henri Mondor, Créteil, France and Centre de recherche de l'Hôpital Laval Québec, Canada
Hôpital Henri Mondor, Créteil, France FOOTNOTES
Conflict of Interest Statement: F.L. does not have a financial relationship with a commercial entity that has an interest in the subject of this manuscript. L.B. has received research contracts with Drager Medical for the conduct of clinical trials concerning the studied system, approximately REFERENCES
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6 ml/kg (Geneva). This is, however, what was indicated in the guidelines available in these centers, and there is a possibility that it substantially differed from what was really applied in clinical practice. Our goal was to study the efficacy of the system in centers with interest in the topic of weaning, as reflected by written guidelines, and having a reasonable level of staffing, but we did not try to assess the real life application of these guidelines in each center. 
15,000 per year from 2001 to 2004. Drager Medical has provided the equipment necessary for the study, including EVITA 4 ventilators equipped with the Evita Weaning System, and has provided a grant necessary to cover insurance costs, Ethics Committee's administrative fees, and organization of meetings for the investigators and for monitoring purposes. L.B. has received approximately