Objective: To determine the correlation of acute
physiology and chronic health evaluation (APACHE) II score and various
weaning indexes (WIs) with 3- and 7-day weaning outcomes.
Design: Prospective, observational.
Setting: The medical ICU of a teaching, urban
Methods: The study included 118 adults
referred for weaning from mechanical ventilation (MV). Critical care
physicians, critical care nurses, and respiratory care practitioners
were asked to predict whether it would take ≤ 3 days, 4 to 7 days, or≥
8 days to wean each patient from MV. The WIs and APACHE II scores
were measured or calculated. The causes of respiratory failure, the
duration of MV before initiating weaning assessment, and the 3- and
7-day weaning outcomes were obtained. Significance was set at
p < 0.05.
Results: The most common causes of
respiratory failure were pneumonia (38 cases) and acute exacerbation of
COPD (29 cases). Fifty-seven patients (48%) were successfully weaned
from MV within 3 days of weaning assessment, and 67 (57%) were weaned
within 7 days. The percentages of correct prediction of 3-day weaning
outcome by critical care physicians, critical care nurses, and
respiratory care practitioners were 64%, 62%, and 59%, respectively;
for 7-day weaning outcome, 60%, 64%, and 58%, respectively. The
successfully weaned groups had significantly lower APACHE II scores and
higher maximal inspiratory pressures than the unsuccessfully weaned
(failure) groups. There were no significant differences between the two
groups for the remaining indexes, including rapid shallow breathing,
dynamic compliance, static compliance, spontaneous respiratory rate,
and the ratio of Pao2 to the fraction of
Conclusions: The overall severity of
illness as assessed by APACHE II score correlates better with 3- and
7-day weaning outcome than the published WIs.