© 2004 American Thoracic Society
Noninvasive Ventilation and WeaningTo the Editor:Ferrer and colleagues (1) have made an important contribution to the evolving literature on the use of noninvasive ventilation (NIV) in the management of patients with acute respiratory failure (2). Their results extend the conclusions of others (3) that NIV can be a useful adjunct to conventional weaning techniques. However, they neglected to report an important population variable that I believe is critical for determination of the external validity of their results: namely, the proportion of patients in their intensive care unit (ICU) who receive initial treatment with NIV. There is evidence that NIV is underused for acute respiratory failure (4). Differing rates of NIV utilization for initial respiratory failure could obviously lead to ventilated ICU cohorts with disparate severities of illness, as well as other factors. Caution might, therefore, be warranted in extrapolation of their results to ICU populations with lower or higher initial utilization rates and would suggest that the first order of business with regard to NIV is to increase its use to avert invasive mechanical ventilation altogether.
Johns Hopkins Hospital Baltimore, Maryland FOOTNOTES Conflict of Interest Statement: S.K.A. has no declared conflict of interest. REFERENCES
From the Authors: We thank Dr. Aberegg for his interest in our recent publication (1). With regard to the proportion of patients initially treated with noninvasive ventilation (NIV), this was 19% in our units over the period in which the study was active. The relevance of this information to the extent that we neglected to report this raw proportion is, however, doubtful for several reasons. First, the rate of utilization of NIV in an intensive care unit depends, among other factors, on the type of patients admitted in these units; the different proportion of patients admitted for diseases in which NIV is a well established clinical indication, such as chronic obstructive pulmonary disease exacerbation (2), is a major determinant of the use of NIV. Second, the potential relevance of the initial failure to respond to NIV treatment leading to intubation in the likelihood that subsequent benefit from NIV during weaning from invasive mechanical ventilation may occur is a question not yet addressed in the literature. Our study was performed in a selected and well defined population of patients who persistently did not respond to weaning attempts (1). Therefore, these results do not have to be extrapolated to other populations; this is not in relation with the statement that the first order of business with regard to NIV is averting intubation and invasive mechanical ventilation, as this is widely accepted (3, 4).
Institut Clínic de Pneumologia i Cirurgia Toracica Hospital Clínic Barcelona, Spain FOOTNOTES Conflict of Interest Statement: M.F. and A.T. have no declared conflict of interest. REFERENCES
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