Reliability of the Determination of the Ventilatory Threshold in Patients with COPD.

PURPOSE: The purpose of this study was to determine the interobserver reliability of the assessment of the ventilatory threshold (VT) using two methods in patients with chronic obstructive pulmonary disease (COPD) and in control subjects. METHODS: VT was identified from incremental exercise testing graphs of 115 subjects (23 controls and 23 in each COPD Global initiative for chronic Obstructive Lung Disease class) by two human observers and a computer analysis using the V-slope method and the ventilatory equivalent method (VEM). Agreement between observers in identifying oxygen uptake at VT (VO 2VT) and HR at VT (HR VT) across disease severity groups was evaluated using intraclass correlation (for humans) and Passing-Bablok regression analysis (human vs computer). RESULTS: For human observers, ICC (95% confidence interval) in determining VO 2VT were higher in controls (0.98 (0.97-0.99) both with V-slope and with VEM) than those in COPD patients (0.72 (0.60-0.81) with V-slope and 0.64 (0.50-0.74) with VEM). Passing-Bablok analysis showed that human and computerized determination of VO 2VT was interchangeable in controls but not in patients with COPD. Forced expiratory volume in one second and peak minute ventilation during exercise were the only variables independently associated with greater interobserver differences in VO 2VT. Interobserver differences in HRVT ranged from 2 ± 1 (controls) to 10 ± 3 bpm (GOLD 4). CONCLUSIONS: In patients with COPD, the reliability of human estimation of VO 2VT is less than that in controls and not interchangeable with a computerized analysis. This should be taken into account when using VT for exercise prescription, as a tool to monitor responses to an intervention, as a surrogate measure of overall aerobic fitness, or as a prognostic marker in patients with COPD.

Mild cognitive impairment in moderate to severe COPD: a preliminary study.

BACKGROUND: Cognitive impairment is a frequent feature of COPD. However, the proportion of patients with COPD with mild cognitive impairment (MCI) is still unknown, and no screening test has been validated to date for detecting MCI in this population. The goal of this study was to determine the frequency and subtypes of MCI in patients with COPD and to assess the validity of two cognitive screening tests, the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA), in detecting MCI in patients with COPD. METHODS: Forty-five patients with moderate to severe COPD and 50 healthy control subjects underwent a comprehensive neuropsychologic assessment using standard MCI criteria. Receiver operating characteristic curves were obtained to assess the validity of the MMSE and the MoCA to detect MCI in patients with COPD. RESULTS: MCI was found in 36% of patients with COPD compared with 12% of healthy subjects. Patients with COPD with MCI had mainly the nonamnestic MCI single domain subtype with predominant attention and executive dysfunctions. The optimal MoCA screening cutoff was 26 (≤ 25 indicates impairment, with 81% sensitivity, 72% specificity, and 76% correctly diagnosed). No MMSE cutoff had acceptable validity. CONCLUSIONS: In this preliminary study, a substantial proportion of patients with COPD were found to have MCI, a known risk factor for dementia. Longitudinal follow-up on these patients is needed to determine the risk of developing more severe cognitive and functional impairments. Moreover, the MoCA is superior to the MMSE in detecting MCI in patients with COPD.

Modification of COPD presentation during the last 25 years.

During the last decades progress has been made in the treatment of Chronic Obstructive Pulmonary Disease (COPD). We compared a random sample of patients admitted for an exacerbation in the period 2001-2005 (n = 101), with a random sample of patients hospitalized for the same reason in the period 1980-1984 (n = 51). Patients of the 2001-2005 cohort had a lower FEV1 (48 ± 3 vs. 41 ± 2% predicted, p = 0.01) for similar mean age, gender and body- mass index when compared to the historical sample. Co-morbidities, according to the Charlson's index, were more prevalent in the 2001-2005 cohort compared to the 1980-1984 cohort, with a reduction of hemoglobin (13.9 ± 0.2 gr/dl vs. 14.9 ± 0.2, p < 0.01) and higher prevalence of anemia in the most recent cohort. We found an increase in the use of cardiovascular drugs and respiratory medications over time with exception for the long-term use of oxygen. Despite lower FEV1 and more prevalent co-morbidities, no difference in length of hospitalization (13.6 ± 1.4 days vs. 12.7 ± 0.7 days, p = 0.52) and 30 months survival post-exacerbation was noted (66.6% vs. 69.3%, p = 0.85). Over the course of 20 years, the presentation of COPD patients admitted for an exacerbation seems to be changed towards a more severe phenotype with lower FEV1 and more co-morbidities. As the length of hospitalization and the overall survival were not different between the two samples, a currently improved management of COPD can be hypothesized.

Inspired fraction of carbon dioxide in oxygen supply to chronic pulmonary disease.

Hypoxemic patients with chronic obstructive pulmonary disease (COPD) are at risk of carbon dioxide (CO(2)) retention during oxygen therapy and hypercapnia in COPD is associated with an ominous prognosis. Rebreathing with oxygen mask is possible in practice and possibly affects CO(2) retention due to an increased inspired fraction of CO(2). Its effects on arterial partial pressure of CO(2) during oxygen supply have, to the best of our knowledge, never been studied. We measured the inspired fraction of CO(2) in eighteen non-hypoxemic stable COPD patients with a capnograph during a 5 min trial with two different modes of oxygen supply (oxygen mask without reservoir bag and nasal prongs, respectively at a flow of 10 l/min and 2l/min). We found no significant increase in inspiratory CO(2) concentration. These findings suggest that inspired fraction of CO(2) does not increase markedly during controlled oxygen therapy.