Predictors of exacerbation frequency in chronic obstructive pulmonary disease.

BACKGROUND: Exacerbations of chronic obstructive pulmonary disease (COPD) are sporadic, acute worsening of symptoms. Identifying predictors of exacerbation frequency may facilitate medical interventions that reduce exacerbation frequency and severity. The objective of this study was to determine predictors of exacerbation frequency and mortality. METHODS: A total of 227 COPD patients were enrolled in a prospective clinical study between January 2000 and December 2011. Reported exacerbations were recorded for the year preceding enrollment and annually thereafter, and patients were grouped by median annual exacerbation frequency into those experiencing infrequent exacerbations (less than one exacerbation annually) and frequent exacerbations (one or more exacerbation annually). Patients experiencing frequent exacerbations were further divided into those experiencing moderately frequent exacerbations (fewer than two exacerbations per year) and severely frequent exacerbations (two or more exacerbations per year). The rate of clinical relapse and survival was recorded over a 10-year period. The mean of follow-up time was 5.15 years per patient. RESULTS: For patients experiencing infrequent, moderately frequent, and severely frequent exacerbations, median exacerbations in the year preceding enrollment were 0.0, 0.5, 1.0, respectively, and more frequent exacerbations correlated with lower baseline forced expiratory volume in one second (FEV1) (0.81 L, 0.75 L, and 0.66 L, respectively), higher comorbidity (70.7%, 75.0%, and 89.4%, respectively), and greater NPPV use during hospitalization (16.4%, 35.9% and 51.1%, respectively). FEV1 declined and mortality increased with increasing exacerbation frequency. CONCLUSIONS: Exacerbation frequency can be used to generate discreet patient subpopulations, supporting the hypothesis that multiple COPD phenotypes exist and can be used in patient risk stratification.

[The clinical application of bi-level positive airway pressure noninvasive ventilator for home mechanical ventilation via tracheostomy in patients with amyotrophic lateral sclerosis].

OBJECTIVE: To study the feasibility of the bi-level positive airway pressure (BiPAP) non-invasive ventilator used in home mechanical ventilation for long-term tracheostomy-mechanical ventilation (TMV) in patients with amyotrophic lateral sclerosis (ALS). METHODS: Sixteen patients (12 men and 4 women, mean age 59 years) with ALS were selected for this study at Respiratory Department of the Shougang Hospital, Peking University from January 2002 to March 2008. After the disease had been controlled by anti-infective therapy and comprehensive treatment, the patients received TMV, through the improved ("Xiang's" connection) non-invasive BiPAP ventilator connected with tracheotomy tube, and on-going home mechanical ventilation (HMV). The blood gas was evaluated during invasive ventilation and non-invasive ventilation before discharge. Family members of the patients were trained for the use of non-invasive ventilators. The use of ventilators and the patients' condition were regularly followed and the survival rate calculated. Statistical analysis was carried out by using one-way ANOVA. RESULTS: There was no statistical difference in the blood gas before the use of non-invasive ventilator, 2 h and 1 d after the use of non-invasive ventilator, and before discharge, PaCO2 [(36+/-10), (42+/-11), (41+/-10), (42+/-11) mm Hg (1 mm Hg=0.133 kPa)], PaO2 [(84+/-11), (81+/-12), (87+/-14), (86+/-12) mm Hg], SaO2 [(96.7+/-1.3)%, (96.5+/-0.8)%, (96.8+/-1.2)%, (96.5+/-1.0)%] respectively, (F=1.21, 0.59, 0.97, 0.41, respectively, all P>0.05). All patients had no complaint of uncomfortable use, no intolerance to ventilators, and no ventilator breakdown. Fifteen patients were alive at the end of the follow-up (July 31, 2008). The mean time of using non-invasive ventilator was 39 months (range 4 to 66 months). CONCLUSION: For ALS patients who need long-term ventilation support, the use of BiPAP non-invasive ventilators is a safe and effective alternative for invasive ventilators.

[The efficacy and safety of long term home noninvasive positive pressure ventilation in patients with stable severe chronic obstructive pulmonary disease].

OBJECTIVE: To evaluate the long term efficacy and safety of long term home noninvasive positive pressure ventilation (HNPPV) in stable hypercapnic patients with chronic obstructive pulmonary disease (COPD). METHODS: Forty patients with stable severe COPD [arterial PaCO2>or=55 mm Hg (1 mm Hg=0.133 kPa)] after hospital discharge were divided into 2 groups: the HNPPV group (n=20) with conventional therapy and HNPPV, and the control group (n=20) with conventional therapy only. Parameters before and after 2 year follow-up observation were compared, which included dyspnea grade, scale for accessory muscle use, scoring for emotional disorders, lung function test, arterial blood gases, 6-min walking distance (6MWD), mean pulmonary arterial pressure (mPAP) by electrocardiography, mortality and hospitalization rates. RESULTS: The age, gender, height, weight, dyspnea grade, scale for accessory muscle use, anxiety scores, depression scores, 6MWD, mPAP, arterial PaCO2 and PaO2, FVC, FEV1, and hospitalization rates of the 2 groups on admission were similar (t values were 1.08, 1.15, 1.20, 1.09, 0.86, 0.54, 0.00, 0.00, 0.43, 0.96, 0.76, 0.38, 0.26, 0.24 and 0.87 respectively, all P>0.05). The mortality was reduced slightly by HNPPV but with no statistically significant difference (3/20 and 8/20, respectively, chi2=3.27, P>0.05). After 2 years, the difference of the dyspnea grade, scale for accessory muscle use, anxiety scores, depression scores, arterial PaCO2 and PaO2, 6MWD, mean pulmonary artery pressure, and hospitalization rates in the HNPPV group [2.4+/-0.5, 2.6+/-0.6, 6.9+/-2.1, 6.1+/-1.6, (49.5+/-2.2) mm Hg, (60.8+/-4.7) mm Hg, (213+/-45) m, (30.3+/-2.2) mm Hg, (1.4+/-0.4) times/year] was statistically significant compared to the control group [3.9+/-0.3, 4.8+/-0.4, 11.2+/-2.6, 11.6+/-2.1, (61.5+/-2.3) mm Hg, (52.8+/-2.4) mm Hg, (127+/-23) m, (36.4+/-2.3) mm Hg, (3.9+/-0.3) times/year] (t values were 9.53, 10.83, 4.92, 7.83, 14.07, 5.41, 6.07, 4.81 and 10.22 respectively, all P<0.01). CONCLUSION: Long-term use of home noninvasive positive ventilation in patients with stable severe COPD is effective and safe.