Differences in baseline factors and survival between normocapnia, compensated respiratory acidosis and decompensated respiratory acidosis in COPD exacerbation: A pilot study.

BACKGROUND AND OBJECTIVE: Patients with chronic obstructive pulmonary disease (COPD) experiencing acute exacerbation (AE-COPD) with decompensated respiratory acidosis are known to have poor outcomes in terms of recurrent respiratory failure and death. However, the outcomes of AE-COPD patients with compensated respiratory acidosis are not known. METHODS: We performed a 1-year prospective, single-centre, cohort study in patients surviving the index admission for AE-COPD to compare baseline factors between groups with normocapnia, compensated respiratory acidosis and decompensated respiratory acidosis. Survival analysis was done to examine time to readmissions, life-threatening events and death. RESULTS: A total of 250 patients fulfilling the inclusion and exclusion criteria were recruited and 245 patients were analysed. Compared with normocapnia, both compensated and decompensated respiratory acidosis are associated with lower FEV1 % (P < 0.001), higher GOLD stage (P = 0.003, <0.001) and higher BODE index (P = 0.038, 0.001) and a shorter time to life-threatening events (P < 0.001). Comparing compensated and decompensated respiratory acidosis, there was no difference in FEV1 (% predicted) (P = 0.15), GOLD stage (P = 0.091), BODE index (P = 0.158) or time to life-threatening events (P = 0.301). High PaCO2 level (P = 0.002) and previous use of non-invasive ventilation (NIV) in acute setting (P < 0.001) are predictive factors of future life-threatening events by multivariate analysis. CONCLUSIONS: Compared with normocapnia, both compensated and decompensated respiratory acidosis are associated with poorer lung function and higher risk of future life-threatening events. High PaCO2 level and past history of NIV use in acute settings were predictive factors for future life-threatening events. Compensated respiratory acidosis warrants special attention and optimization of medical therapy as it poses risk of life-threatening events.

A pilot randomized study comparing two methods of non-invasive ventilation withdrawal after acute respiratory failure in chronic obstructive pulmonary disease.

BACKGROUND AND OBJECTIVE: Patients with chronic obstructive pulmonary disease (COPD) presenting with acute hypercapnic respiratory failure (AHcRF) benefit from non-invasive ventilation (NIV). The best way to withdraw NIV is not known, and we conducted a pilot study comparing stepwise versus immediate withdrawal of NIV in these patients. METHODS: This was a prospective, single-centre, open-labelled randomized study comparing stepwise versus immediate withdrawal of NIV in patients with COPD exacerbation recovering from AHcRF. The primary end-point was the success rate of NIV withdrawal, defined as no restarting of NIV from randomization to 48 h after complete withdrawal of NIV. RESULTS: Sixty patients were randomized, 35 patients to stepwise withdrawal and 25 patients to immediate withdrawal. The two study arms were clinically comparable. There was no statistically significant difference in the success rate, with NIV successfully stopped in 74.3% and 56% in the stepwise and immediate withdrawal groups, respectively (P = 0.139). CONCLUSIONS: We could not show any benefits for either strategy to withdraw NIV. The study may have been underpowered to detect differences, and larger prospective studies are required.

Sleep apnea is a novel risk predictor of cardiovascular morbidity and death in patients receiving peritoneal dialysis.

Sleep apnea syndrome is increasingly recognized in peritoneal dialysis patients; however, its prognostic implication in this population is unknown. To study this, we prospectively followed the clinical outcome of 93 peritoneal dialysis patients with baseline polysomnography. Of these, 51 were diagnosed with the syndrome defined by an apnea-hypopnea index (AHI) of at least 15 per hour. During a median follow-up of 41 months, there were 30 deaths, of which 17 were due to cardiovascular causes. Kaplan-Meier analysis for the entire follow-up period indicated that patients with sleep apnea at baseline had significantly higher all-cause and cardiovascular mortality during follow-up than those without. Minimal nocturnal saturation and desaturation indices were predictors of mortality and cardiovascular events at univariate analysis. Multivariable Cox regression analysis identified significant sleep apnea syndrome at baseline as an independent predictor of increased all-cause mortality independent of age, male gender, and diabetic status. Further, an absolute increase in the AHI was associated with an incremental risk of cardiovascular events. Thus, sleep apnea syndrome, detected at the start of peritoneal dialysis, is a novel risk predictor for subsequent mortality and cardiovascular events.

Alleviation of sleep apnea in patients with chronic renal failure by nocturnal cycler-assisted peritoneal dialysis compared with conventional continuous ambulatory peritoneal dialysis.

Nocturnal hemodialysis has been shown to improve sleep apnea in patients who receive conventional hemodialysis. It was hypothesized that nocturnal peritoneal dialysis (NPD) also is effective in correcting sleep apnea in patients who receive continuous ambulatory PD (CAPD). Overnight polysomnography (PSG) was performed in 46 stable NPD and CAPD patients who were matched for demographic and clinical attributes. The prevalence of sleep apnea, defined as an apnea-hypopnea index (AHI; or frequency of apnea and hypopnea per hour of sleep) > or =15, was 52% for NPD patients and 91% for CAPD patients (P = 0.007). The mean (+/-SD) AHI in NPD and CAPD patients was 31.6 +/- 25.6 and 50.9 +/- 26.4 (P = 0.025), respectively. For validation of the efficacy of NPD in alleviating sleep apnea, a fixed sequence intervention study was performed in which 24 incident PD patients underwent one PSG study during mandatory cycler-assisted NPD while awaiting their turn for CAPD training and a second PSG recording shortly after they were established on stable CAPD. The prevalence of sleep apnea was 4.2% during NPD and 33.3% during CAPD (P = 0.016). AHI increased from 3.4 +/- 1.34 during NPD to 14.0 +/- 3.46 during CAPD (P < 0.001). With the use of bioelectrical impedance analysis, total body water content was significantly lower during stable NPD than CAPD (32.8 +/- 7.37 versus 35.1 +/- 7.35 L; P = 0.004). NPD delivered greater reductions in total body water (-2.81 +/- 0.45 versus -1.34 +/- 0.3 L; P = 0.015) and hydration fraction (-3.63 +/- 0.64 versus -0.71 +/- 0.52%; P = 0.005) during sleep. Pulmonary function tests remained unchanged before and after conversion from NPD to CAPD. These findings suggest that NPD may have a therapeutic edge over CAPD in sleep apnea that is associated with renal failure as a result of better fluid clearance during sleep.

Fulminant community-acquired Acinetobacter baumannii pneumonia as a distinct clinical syndrome.

STUDY OBJECTIVES: Acinetobacter baumannii (AB) is an important cause of hospital-acquired pneumonia (HAP), and an uncommon but important cause of community-acquired pneumonia (CAP) with high mortality. To better characterize CAP-AB, we compared its clinical features and outcomes with a control group of HAP-AB patients. METHODS: This is a retrospective case-control study comparing CAP-AB and HAP-AB patients, which was performed at United Christian Hospital between July 2000 and December 2003. RESULTS: There were 19 cases of CAP-AB and 74 cases of HAP-AB. When compared with the HAP-AB group, the CAP-AB group had more ever-smokers (84.3% vs 55.4%, respectively; p = 0.031), more COPD patients (63.2% vs 29.7%, respectively; p = 0.014), and fewer median days of hospitalization (HAP-AB group, median, 0 days; CAP-AB group, 0 days [range, 0 to 30 days]; p = 0.049) in the previous year. The CAP-AB group had more patients with positive blood culture findings (31.6% vs 0%, respectively; p < 0.001), a higher frequency of ARDS (84.2% vs 17.6%, respectively; p < 0.001), and disseminated intravascular coagulation (DIC) (57.9% vs 8.1%, respectively; p < 0.001). The median survival time was only 8 days in the CAP-AB group, vs 103 days in the HAP-AB group (p = 0.003). Factors associated with the higher mortality in the CAP-AB group included the presence of AB bacteremia (p = 0.040), platelet count of < 120 x 10(9) cells/L (p = 0.026), pH < 7.35 on presentation (p = 0.047), and the presence of DIC (p = 0.004). CONCLUSIONS: CAP-AB appears to be a unique clinical entity with a high incidence of bacteremia, ARDS, DIC, and death, when compared to HAP-AB. Further studies are needed to investigate the mechanism of the fulminant nature of CAP-AB.

Initial viral load and the outcomes of SARS.

BACKGROUND: Severe acute respiratory syndrome (SARS) is caused by a novel coronavirus. It may progress to respiratory failure, and a significant proportion of patients die. Preliminary data suggest that a high viral load of the SARS coronavirus is associated with adverse outcomes in the intensive care unit, but the relation of viral load to survival is unclear. METHODS: We prospectively studied an inception cohort of 133 patients with virologically confirmed SARS who were admitted to 2 general acute care hospitals in Hong Kong from Mar. 24 to May 4, 2003. The patients were followed until death or for a minimum of 90 days. We used Cox proportional hazard modelling to analyze potential predictors of survival recorded at the time of presentation, including viral load from nasopharyngeal specimens (measured by quantitative reverse transcriptase polymerase chain reaction [PCR] of the SARS-associated coronavirus). RESULTS: Thirty-two patients (24.1%) met the criteria for acute respiratory distress syndrome, and 24 patients (18.0%) died. The following baseline factors were independently associated with worse survival: older age (61-80 years) (adjusted hazard ratio [HR] 5.24, 95% confidence interval [CI] 2.03-13.53), presence of an active comorbid condition (adjusted HR 3.36, 95% CI 1.44-7.82) and higher initial viral load of SARS coronavirus, according to quantitative PCR of nasopharyngeal specimens (adjusted HR 1.21 per log10 increase in number of RNA copies per millilitre, 95% CI 1.06-1.39). INTERPRETATION: We found preliminary evidence that higher initial viral load is independently associated with worse prognosis in SARS. Mortality data for patients with SARS should be interpreted in light of age, comorbidity and viral load. These considerations will be important in future studies of SARS.

Noninvasive ventilation in patients with acute hypercapnic exacerbation of chronic obstructive pulmonary disease who refused endotracheal intubation.

OBJECTIVE: To determine the long-term outcome of noninvasive ventilation in chronic obstructive pulmonary disease patients who refused intubation for acute hypercapnic respiratory failure. DESIGN: Prospective, observational study. SETTING: Noninvasive ventilation unit in an acute regional hospital in Hong Kong. METHODS: The study recruited 37 chronic obstructive pulmonary disease patients who had the do-not-intubate code and developed acute hypercapnic respiratory failure. They were offered noninvasive ventilation, and their long-term outcomes were followed. Survival and event-free survival (an event is death or recurrent acute hypercapnic respiratory failure) were analyzed by survival analysis. Their disease profile and outcome were compared with another 43 chronic obstructive pulmonary disease patients without the do-not-intubate codes, who had acute hypercapnic respiratory failure and received noninvasive ventilation during the study period (usual care group). RESULTS: Patients in the do-not-intubate group were significantly older (p =.029), had worse dyspnea score (p <.001), worse Katz Activities of Daily Living score (p <.001), worse comorbidity score (p =.024), worse Acute Physiology and Chronic Health Evaluation II score (p =.032), lower hemoglobin (p =.001), and longer stay in the hospital during the past year (p =.001) than patients who received usual care. In the do-not-intubate group, the median survival was 179 days, and 1-yr actuarial survival was 29.7%; in the usual care group, the median survival was not reached during follow-up, and 1-yr actuarial survival was 65.1% (p <.0001). In the do-not-intubate group, the median event-free survival was 102 days, and 1-yr event-free survival was 16.2%; in the usual care group, median event-free survival was 292 days, and 1-yr event-free survival was 46.5% (p =.0004). CONCLUSIONS: A 1-yr survival of about 30% was recorded in chronic obstructive pulmonary disease patients with the do-not-intubate code who developed acute hypercapnic respiratory failure requiring noninvasive ventilation. The majority of survivors developed another life-threatening event in the following year. Information generated from this study is important to physicians and chronic obstructive pulmonary disease patients when they are considering using noninvasive ventilation as a last resort.

Association of presence of Aspergillus antibodies with hemoptysis in patients with old tuberculosis or bronchiectasis but no radiologically visible mycetoma.

Old tuberculosis and bronchiectasis are the two most important causes of chronic structural changes of lungs in our locality. In the absence of radiologically visible mycetoma, the cause of hemoptysis in these two groups of patients is largely unknown. A 17-month prospective study was carried out to compare the prevalence of Aspergillus fumigatus and Aspergillus flavus antibodies in hemoptysis patients with old tuberculosis or bronchiectasis but no radiologically visible mycetoma (cases, n = 38), hemoptysis patients with other diagnosis (control group 1, n = 29), and patients with old tuberculosis or bronchiectasis but no hemoptysis (control group 2, n = 47) by a recently developed sensitive and specific A. fumigatus and A. flavus antibody assay. There were a significantly larger number of patients with antibody against A. fumigatus or A. flavus among the cases than among the patients in control groups 1 and 2 (P < 0.05 in both comparisons). Molds were not recovered from any of the patients. Among the 10 cases with Aspergillus antibody, eight and two had antibody against A. flavus and A. fumigatus, respectively. We conclude that there was an association between the presence of Aspergillus antibodies and hemoptysis in patients with old tuberculosis or bronchiectasis, suggesting that these patients probably had occult infections caused by the corresponding fungi. Development of serological tests against other Aspergillus species as well as other causes of mycetoma will probably increase the detection of occult mold infections in patients with existing parenchymal lung diseases, and treatment of fungal microinvasion may help to alleviate hemoptysis in these patients with bronchiectasis or old tuberculosis who have Aspergillus antibodies.