[Comparison of SmartCare and spontaneous breathing trials for weaning old patients with chronic obstructive pulmonary diseases].

OBJECTIVE: To compare the outcome of the SmartCare and spontaneous breathing trials (SBT) for weaning old patients with chronic obstructive pulmonary diseases (COPD).

METHODS: Thirty-eight COPD patients were enrolled in Department of Respiratory Medicine on the South Building, General Hospital of People's Liberation Army from January, 2003 to April, 2005. They mechanically ventilated for at least 3 d (age: 70 - 91 year, average: 83.3 +/- 4.3), randomly assigned to receive SmartCare (SC group, n = 13) or SBT (SBT group, n = 25). All patients were considered clinically and biologically stable, and therefore ready to be weaned from mechanical ventilation. In SC group, patients were ventilated with an inspiratory pressure (IPAP) support adjusted to achieve pH value > or = 7.35, saturation of oxygen in arterial blood (SaO2) > or = 90%, respiratory frequency (RR) > or = 10 and < or = 30 breaths/min, and fraction of inspired oxygen (FiO2) < or = 45%. In SBT group, the patients were placed in a weaning protocol utilizing increasing duration of spontaneous breathing. The following data were recorded at weaning: the acute physiology and chronic health evaluation II (APACHE II) score, arterial blood gases under mechanical ventilation, serum calcium, magnesium, and phosphorus, the days of ventilation before weaning and the duration of weaning. The patients of both groups were considered as successfully weaned when they were able to tolerate at least 48 consecutive hours of spontaneous breathing. Failure was defined in a patient who died during the weaning process or who still needed mechanical ventilation after at least 40 consecutive days of weaning.

RESULTS: No significant differences were found between the groups at the onset of weaning from mechanical ventilation regarding APACHE II, serum albumin, calcium, magnesium, phosphorus, partial pressure of carbon dioxide in arterial blood (PaCO2), and the days of mechanical ventilation (t = 0.834, 0.696, 1.384, 0.682, 0.467, 0.816, 0.384, all P > 0.05). The pH value of the SBT group (7.45 +/- 0.05) was higher than the SC group (7.40 +/- 0.04, t = 3.263, P < 0.05). Although patients in the SC group spent less time in weaning than those in the SBT group, the difference was not significant [(8.54 +/- 2.09), (13.32 +/- 2.19) d for the SC and SBT groups, respectively, t = 1.320, P = 0.251]. The 7-d weaning success rate was greater in the SC group than the SBT group (77%, 40%, chi(2) = 4.677, P = 0.031). No significant difference was found in 14-d weaning success rate (77%, 64% in the SC and SBT groups, chi(2) = 0.661, P = 0.416). Fewer arterial blood analyses were performed in the SC group (3.5 +/- 3.1, 6.6 +/- 3.7, t = 2.710, P = 0.011).

CONCLUSION: The SmartCare is better than SBT in weaning patients with COPD within 7 days.