1995 OPEN FORUM Abstracts
MEASUREMENT OF THE DYNAMIC RAPID SHALLOW BREATHING INDEX
SW Munroe MS, RRT, JD Zibrak MD, KM Dushay MD, C O'Donnell, Sc .D., MPH, M Feldman BS, RRT, KG Kendrick BS, RRT, GF MacDonald MBA, RRT, P Burke MD. Departments of Respiratory Care, Pulmonary Medicine, and General Surgery, Deaconess Hospital, Harvard Medical School, Boston, MA.
INTRODUCTION: A static RSBI of and > 105 has been shown to be both a good positive and negative predictor of weaning outcome respectively. We hypothesized that the dynamic RSBI measured over the course of a weaning trial on a minimal level of inspiratory pressure support (IPS) is a reliable predictor of weaning outcome.
Methods: We studied 12 stable patients who were being considered for extubation. We measured standard ventilatory mechanics, the static and dynamic RSBI on a minimum level of IPS. Data was analyzed for significance using the Mann Whitney test.
Results: Of the 12 patients studied, 7 were extubated successfully and 5 patients failed extubation. Duration of weaning trials ranged from 1 to 14 hours (mean of 5.1 hours). All of the patients who were extubated successfully satisfied standard weaning criteria including a static RSBI of and an average dynamic RSBI of. Of the patients who failed extubation, all 5 patients were unable to satisfy standard weaning criteria and had a static RSBI of > 105. Of these 5 patients, 4 patients had an average dynamic RSBI of > 105, while 1 patient had an average dynamic RSBI of 67.5 but still failed extubation. The static RSBI predicted weaning outcome in all 12 patients (p=0.002). The dynamic RSBI predicted weaning outcome in 11 out of 12 patients (p=0.005). CONCLUSION: In this small sample of patients, the dynamic RSBI was a reliable predictor of weaning outcome but not as good as the static RSBI and standard weaning criteria.
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