Sk. Epstein, ETIOLOGY OF EXTUBATION FAILURE AND THE PREDICTIVE VALUE OF THE RAPID SHALLOW BREATHING INDEX, American journal of respiratory and critical care medicine, 152(2), 1995, pp. 545-549
Citations number
33
Categorie Soggetti
Emergency Medicine & Critical Care","Respiratory System
Failure of weaning from mechanical ventilation is thought to result fr
om an imbalance between respiratory muscle capacity and respiratory de
mand. The ratio of respiratory rate to tidal volume (f/VT, rapid shall
ow breathing index) during spontaneous unsupported respiration increas
es when this imbalance exists, and may predict the success or failure
of weaning from mechanical ventilation. Using f/VT, Yang and Tobin dem
onstrated a positive predictive value (PPV) of 0.78 (f/VT less than or
equal to 105 and weaning success) (1). To define the etiology of the
20% false-positive rate (FPR, f/VT less than or equal to 105 and weani
ng failure), 94 patients who had an f/VT determined prior to extubatio
n were studied prospectively. Of 84 patients with an f/VT < 100, 14 re
quired reintubation within 72 h of extubation (FPR = 0.17, PPV = 0.83)
. Extubation in 13 of these 14 cases failed because of congestive hear
t failure, upper airway obstruction, aspiration, encephalopathy, or th
e development of a new pulmonary process. Only one patient needed rein
tubation solely because of the original respiratory process. Of 10 pat
ients extubated with an f/VT greater than or equal to 100, four requir
ed reintubation, all because of the underlying respiratory process. Th
is study confirms the high PPV for an f/VT < 100. The FPR of approxima
tely 0.20 is best explained by extubation failure caused by processes
for which f/VT is physiologically or temporally unlikely to predict su
ccess or failure. The negative predictive value (f/VT greater than or
equal to 100 but extubation success) for f/VT may be lower than previo
usly reported.