Analysis Of Prognostic Factors About Elderly Patients Receiving Mechanical Ventilation

Objective:This study was designed to get the message about weaning and survival in elderly patients receiving mechanical ventilation(MV), to determine the influential factors of ventilator-weaning and then to investigate the prognostic factors for survival, so as to guide the clinical treatment of ventilated elderly patients.Methods:A cohort of 600 elderly patients from senile wards receiving MV from January 1998 to December 2007 were retrospectively studied. All the enrolled patients were 65 years old and over, most of them suffered with hypertension, coronary heart disease, diabetes, cerebral apoplexy. the main etiology of MV included pneumonia, acute exacerbation of chronic obstructive pulmonary disease, aspiration, acute cardiac insufficiency, myocardial infarction, acute cerebral apoplexy, et al. Important parameters were gathered, such as age, pre-existed diseases, blood gas analysis and acute physiology score(APS) of pre-intubation, etiology of MV, complications, duration of MV, live time and so on. weaning rate and survival rate were calculated. The threshold of MV duration when successful weaning occurred was obtained by ROC curve, on this basis, the patients were divided into "weaning success group" and "weaning failure group", All related variables were evaluated by multivariate logistic regression analysis. Then all factors potentially related to mortality were analyzed by COX proportional hazards model.Results:1. The mean age of all enrolled patients was 82.9±5.2,eighty years old and over accounted 76%,the patients with more than two co-mobidity accounted 88%.the mean duration of MV was 114±237 days,279 patients(46%) ventilated for more than 30 days,104 patients(17%) ventilated for more than 6 months. 2.232 patients (39%) successfully ventilator-weaned, ninety-four percent of the weaning occurred within 2 months of MV.3. The median survival duration was 153 days, the overall mortality rate of 2 months,6 months,1 year was 42%,52%,64%,respectively. The mortality rate of 2 months,6 months,1 year for ventilator-weaned patients was 16%,17%,39%, the corresponding mortality rate for non-weaned patients was 58%,74%,80%, respectively.4. Univariate analysis revealed that age, pre-existed respiratory diseases, PH and APS of pre-intubation, albumin, tracheotomy, multiple organ dysfunction syndrome(MODS) during MV were significantly different between the "weaning success group" and "weaning failure group" (p<0.05). Using multivariate logistic regression analysis, the variables independently associated with weaning were:co-existed respiratory diseases (p=0.02, OR 0.29,95%CI 0.16-0.52), tracheotomy (p=0.04, OR 0.42,95%CI 0.18-0.98),MODS during MV (p<0.001, OR 0.012,95%CI 0.002-0.093)5. Univariate analysis of survival showed that differences in age, APS, history of intubation, pre-existed respiratory diseases, chronic renal insufficiency, weaning success, tracheotomy, MODS during MV were significant (p<0.05), COX proportional hazards model revealed APS, chronic renal insufficiency,weaning success, tracheotomy, MODS during MV were independent prognostic factors for survival, the risk factors of survival were: APS (p=0.003, OR 1.93,95%CI 1.24-2.9),chronic renal insufficiency (p=0.02, OR 2.62,95%CI 2.04-3.25),MODS during MV (p=0.01, OR 1.48,95%CI 1.07-2.04), the protection factors of survival were:weaning success (p<0.001, OR 0.09,95%CI 0.04-0.20),tracheotomy (p＜0.001, OR 0.43,95%CI 0.29-0.63)Conclusions:The "time window of weaning" for ventilated elderly patients was within 2 months, almost half of patients could survival for 6 months. The weaning and the ultimate survival of ventilated elderly patients depended not only on the factors present at the start of MV, but also on the development of complications and treatment strategy during MV. It was essential to correctly evaluate the influential factors of weaning and ultimate survival for improvement of prognosis in ventilated elderly patients.