Dear editor,

Among mechanically ventilated patients, those with chronic obstructive pulmonary disease (COPD) diagnosis constitute important and major part of difficult-to-wean patients.1 Prevalence of extubation failure in these patients ranges from 35% to 67%.2,3 Knowing extubation failure prolongs mechanical ventilation duration and intensive care unit and hospital length of stay, studies has been carried out to define factors predicting extubation failure.4 We read with great interest the article written by Nantsupawat et al5 entitled "Factors Associated With Reintubation in Patients With Chronic Obstructive Pulmonary Disease" published in Quality Management in Health Care. The study retrospectively reviewed data of patients with COPD over a 3-year period, included and analyzed 82 intubated patients with COPD 11 of whom were reintubated. They found that sedative and analgesic drug use before extubation was associated with more frequent reintubation in patients with acute exacerbations of COPD. This study enables to guide clinicians to be aware of contributing factors for reintubation and also provide protocoled approach to patients with high risk for weaning failure. However, we think that there are some issues to be commented on.

First, authors used "good cough" in univariate and multiple logistic regression analysis and found this variable as statistically significant predictor of successful extubation. However, in this study there is no enough definition or information about measurement of good cough. Also time of this evaluation (preextubation or postextubation period) was not stated. Khamiees et al6 developed a semi-quantitative cough strength score (SCSS), graded from 0 (weak) to 5 (strong), to predict reintubation after planned extubation. They found that the patients with a lower SCSS had a greater risk of reintubation. In a recent study, it is demonstrated that cough peak flow measured by spirometry has good sensitivity and specificity also as accurate as SCSS for predicting reintubation after planned extubation.7 We believe that it is necessary to use more standardized and quantitative measurement for definition of "good cough."

Second, data about use of noninvasive mechanical ventilation (NIMV) in both reintubated and successfully extubated groups is not given in detail. It was shown that NIMV should be preferentially used during weaning process especially in patients with COPD.8 However, some concerns about NIMV treatment remains blurred in this study. How many of these intubated patients enrolled in the study had NIMV therapy before intubation? Is there any patient in the successfully extubated group? Why did only 5 of reintubated patients take NIMV treatment? We think that answers to these questions are needed to make complete comprehensive assessment.

Despite a small number of patients with outcome to make effective multiple regression models, this study gives valuable and useful information about factors predicting successful extubation in patients with COPD. We consider large randomized clinical based prospective studies for determining factors for extubation success or failure in these patients.

-Cuneyt Salturk, MD

Department of Intensive Care Unit, Sureyyapasa Chest

Disease and Research Hospital, Istanbul, Turkey

-Antonio M. Esquinas, MD, PhD, FCCP

Intensive Care and Non Invasive Ventilatory Unit, Hospital

Morales Meseguer, Murcia, Spain

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