Fractal dimension in CT low attenuation areas is predictive of long-term oxygen therapy initiation in COPD patients: Results from two observational cohort studies

BackgroundSome chronic obstructive pulmonary disease (COPD) patients develop hypoxemia with disease progression, with some even requiring long-term oxygen therapy (LTOT). Lung function, especially diffusing capacity, and the annual decline in PaO₂, are reported to be predictive factors of chronic respiratory failure. However, the association between lung morphometry evaluated using computed tomography (CT) images and LTOT initiation is unknown.MethodsWe retrospectively evaluated the relationship between clinical indices, including pulmonary function, body mass index (BMI), and CT parameters, at baseline and LTOT initiation in two prospective COPD cohorts. In the Nara Medical University cohort (n = 76), the low attenuation area (LAA) and its fractal dimension (fractal D) were adapted as the indices for parenchymal destruction in CT images. The association between these CT measurements and LTOT initiation was replicated in the Kyoto University cohort (n = 130).ResultsIn the Nara Medical University cohort, lower BMI (hazard ratio [HR]:0.70, p = 0.006), lower % diffusing capacity (%DLCO) (HR: 0.92, p = 0.006), lower %DLCO/VA (HR, 0.90, p = 0.008), higher RV/TLC (HR, 1.26, p = 0.012), higher LAA% (HR: 1.18, p = 0.001), and lower fractal D (HR: 3.27 × 10^?8, p < 0.001) were associated with LTOT initiation. Multivariate analysis in the Kyoto University cohort confirmed that lower %DLCO and lower fractal D were independently associated with LTOT initiation, whereas LAA% was not.ConclusionFractal D, which is the index for morphometric complexity of LAA in CT analysis, is predictive of LTOT initiation in COPD patients.     

Chemotherapy for patients with advanced lung cancer receiving long-term oxygen therapy

Background

Long-term oxygen therapy (LTOT) is sometimes prescribed for patients with advanced lung cancer who are potential candidates for chemotherapy. The aim of this study was to assess the usefulness of chemotherapy for patients with this disease who require LTOT.

Methods

The medical records of 40 patients with advanced lung cancer who received LTOT while undergoing systemic chemotherapy at our institution between January 2009 and December 2014 were retrospectively reviewed. Chemotherapy consisted of cytotoxic or molecular-targeted agents.

Results

Twenty-four patients had adenocarcinoma, 6 had squamous cell carcinoma, and 10 had small cell lung cancer (SCLC). The median survival time from the date of the first chemotherapy cycle performed in conjunction with LTOT was 194 days. In a multivariate analysis, the only factor significantly associated with better prognosis was the line (first or second) of the first chemotherapy with LTOT (hazard ratio =0.42; 95% confidence interval, 0.18 to 0.94). Among the 40 patients, 10 (25%) received chemotherapy during the last 30 days of their lives, 2 of whom died of chemotherapy-related adverse events.

Conclusions

Chemotherapy for patients with advanced lung cancer who receive LTOT may be acceptable if it is the first- or second-line treatment. However, we should be mindful of the potential overuse of chemotherapy and its negative impact on quality of life.     

Time to Steady State after Changes in FIO2 in Patients with COPD

Abstract

Background: International guidelines recommend that when changing FIO₂ in patients with COPD receiving Long-Term Oxygen Therapy (LTOT), 30 minutes should be waited for steady state before measurement of arterial blood gasses. This study evaluates whether 30 minutes is really necessary, as a smaller duration might improve the logistics of care, potentially reducing the time spent by patients at the out-patient clinic. Methods: 12 patients with severe to very severe COPD according to the GOLD guidelines were included. Patients had a median FEV₁% of 23% of the predicted value (range 15–64%), median FEV₁/FVC 0.43 (range 0.26–0.63), and chronic respiratory failure necessitating LTOT, 1–4 liters/minute, minimum 16 hours/day. Following a FIO₂ reduction (wash out), arterial blood gases were measured at 0, 1, 2, 4, 8, 12, 17, 22, 32 and 34 minutes. FIO₂ was then increased to baseline levels (wash in) and blood gasses measured at 0, 1, 2, 4, 8, 12, 17, 22, 32, and 34 minutes. Data were analyzed to examine the dynamics of arterial PO₂ and saturation (SO₂) wash out and wash in by calculating the time constants, tau (ô), and to evaluate the time required to reach values which might be considered clinically stable, defined as PO₂ within 0.5 kPa and SO₂ within 1% of equilibrium values. Results: For arterial PO₂ values of time constants were about 3 minutes and similar for both wash out and wash in. A median of 5 minutes was required to reach clinically stable values of PO₂ in both wash out and wash in, with 7–8 minutes sufficient in 75% of patients, and in the worst case 14 minutes. For SO₂, values of the time constant were 4.5 and 1.4 minutes for wash out and wash in, respectively. The time required to reach clinically stable values was different in the two phases. For wash out the median time was 7.4 minutes, and in the worst case 15.6 minutes. For wash in the median time was 2.6 minutes and in worst case 6.8 minutes. No significant changes in PCO₂ or pH were seen during FIO₂ changes. Discussion/Conclusion: This study shows that oxygen equilibration relevant for clinical interpretation requires only 10 minutes following an increase and 16 minutes following a decrease in FIO₂. over the range studied.     

Comparison of Recording Positions of Physical Activity in Patients with Severe COPD Undergoing LTOT

Abstract

Background: Accelerometry is increasingly used to assess physical activity (PA) in patients with chronic obstructive pulmonary disease (COPD). It is not known how the relationship of PA to clinical results depends on the position of the PA sensor. Methods: We assessed the effect of monitor position by measuring lower extremity (ankle), upper extremity (wrist) and total body movement (hip) in 52 patients with severe COPD (mean [± SD] age, 62 ± 10 years; FEV₁, 38 ± 12% predicted) undergoing long-term oxygen therapy with and without walkers during a pulmonary rehabilitation (PR) program. Sensors were worn 8.5 ± 3.1 days and data was compared to the BODE score and the 6-minute walk distance (6MWD) assessed at the beginning and end of the PR. Results: Mean ankle PA was moderately related to the 6MWD, irrespective of patients being equipped with a walker or not (p < 0.05). Mean PA values were considerably lower in COPD patients with walker compared to patients without for all sensor positions. No significant association was observed between mean hip PA data and 6MWD; however, hip and ankle PA data were moderately related in walker-free and strongly related in walker patients (p < 0.01). In a multivariate regression model only ankle activity was significantly associated with the BODE score (p < 0.01). Conclusion: The sensor position had a significant impact on the association between PA recordings and the 6MWD in very severe COPD. In our setting, ankle measurement seemed to best reflect the clinical state of patients.     

Survival of chronic hypercapnic COPD patients is predicted by smoking habits, comorbidity, and hypoxemia

STUDY OBJECTIVES: Chronic hypercapnia in patients with COPD has been associated with a poor prognosis. We hypothesized that, within this group of chronic hypercapnic COPD patients, factors that could mediate this hypercapnia, such as decreased maximum inspiratory mouth pressure (P(I(max))), decreased maximum expiratory mouth pressure (P(E(max))), and low hypercapnic ventilatory response (HCVR), could be related to survival. Other parameters, such as arterial blood gas values, airway obstruction (FEV1), body mass index (BMI), current smoking status, and the presence of comorbidity were studied as well. METHODS: A cohort of 47 chronic hypercapnic COPD patients recruited for short-term trials (1 to 3 weeks) in our institute was followed up for 3.8 years on average. Survival was analyzed using a Cox proportional hazards model. The risk factors considered were analyzed, optimally adjusted for age and gender. RESULTS: At the time of analysis 18 patients (10 male) were deceased. After adjusting for age and gender, P(I(max)), P(E(max)), and HCVR were not correlated with survival within this hypercapnic group. Current smoking (hazard ratio [HR], 7.0; 95% confidence interval [CI], 1.4 to 35.3) and the presence of comorbidity (HR, 5.5; 95% CI, 1.7 to 18.7) were associated with increased mortality. A higher Pa(O2) affected survival positively (HR, 0.6 per 5 mm Hg; 95% CI, 0.4 to 1.0). Pa(CO2) tended to be lower in survivors, but this did not reach statistical significance (HR, 2.0 per 5 mm Hg; 95% CI, 0.9 to 4.3). FEV1 and BMI were not significantly related with survival in hypercapnic COPD patients. CONCLUSION: In patients with chronic hypercapnia, only smoking status, the presence of comorbidity, and Pa(O2) level are significantly associated with survival. Airway obstruction, age, and BMI are known to be predictors of survival in COPD patients in general. However, these parameters do not seem to significantly affect survival once chronic hypercapnia has developed.     

长期氧疗对COPD患者血凝状态和内皮功能的影响

目的探索长期氧疗对慢性阻塞性肺疾病(COPD)血凝状态和内皮功能的影响。方法56例COPD患者,随机分成两组:1治疗组:30例男19例女11例,平均年龄(72.5±10.1)岁;对照组:26例,男14例,女12例,平均年龄(73.1±9.5)岁。治疗组在出院后开始吸入申威8升压缩氧,吸入氧浓度(FIO2)29%,每日12小时。治疗前后常规检查肺功能(FEV1)、动脉血气、肝、肾功能、血沉(ESR)、血凝及血粘状态指标。结果治疗组治疗后PCV、D-二聚体、血浆及全血粘度(高切和低切)均明显下降(P<0.01);随血凝状态的改善内皮功能也得到改善,ET-1下降。PaO2及SatO2%增高(P<0.01);血肌酐降低(P<0.05);血β2-微球蛋白下降。对照组各指标均无变化。结论LTOT治疗对改善COPD高凝状态和内皮功和肾功能能具有较好的疗效。     

Guidance for home oxygen weaning in the community (PPLOG)

The aim of this home oxygen weaning guidance is to bring evidence-based knowledge and the experiences of Respiratory Clinical Nurse Specialists, Community Children's Nurses and Community Neonatal Nurses together, to address the unwarranted variation across community children & young people (CYP) services in relation to Long Term Oxygen Therapy (LTOT). This guidance has been created with an aim to ensure the management of CYP on home oxygen therapy is safe, effective, timely and standardised within London and other England regions especially when the oxygen process begins.     

Importance of noninvasively measured respiratory muscle overload among the causes of hospital readmission of COPD patients

AIM: To evaluate the influence of respiratory muscle overload and right cardiac overload among the possible risk factors of hospital readmission in a 1-year follow-up of a cohort of patients with moderate-to-severe COPD. METHODS: A total of 112 COPD patients who were admitted consecutively to the hospital for acute exacerbation. At hospital discharge, we evaluated the conventional clinical and functional determinations in addition to the pressure-time index (PTI), which is obtained using the equation PTI = (Pawo/Pimax) x (Ti/Ttot) x 100, where Pawo represents the mean airway pressure measured at the mouth during spontaneous breathing, Pimax is the maximal inspiratory pressure, Ti is the inspiratory time, and Ttot is the total breathing cycle time. A cardiac echo-Doppler examination was carried out when patients were in stable condition and presented clinical signs of right cardiac overload prior to inclusion in the study. RESULTS: Multivariate analysis showed that the use of long-term oxygen therapy (LTOT) and high PTI (> 0.25) were independently related to the risk of hospital readmission. Patients receiving LTOT had higher Paco(2) (p < 0.05), FEV(1) percent predicted (p < 0.05), FVC percent predicted (p < 0.05), and Pao(2) (p < 0.05), and had higher Paco(2) (p < 0.05). An elevated systolic pulmonary arterial pressure (> 40 mm Hg) was also independently related, but only 28 patients had echo-Doppler data that could be used. CONCLUSIONS: At hospital discharge, noninvasively measured respiratory muscle overload as well as the use of LTOT were associated with an increased risk of hospital readmission for exacerbation in patients with moderate-to-severe COPD.     

Effects of a walking aid in COPD patients receiving oxygen therapy

STUDY OBJECTIVES: To elucidate whether a simple walking aid may improve physical performance in COPD patients with chronic respiratory insufficiency who usually carry their own heavy oxygen canister. DESIGN: Randomized crossover trial. SETTING: Physiopathology laboratory of three rehabilitation centers. PATIENTS AND INTERVENTIONS: We studied 60 stable COPD patients (mean age, 70.6 +/- 7.9 years; FEV(1), 44.8 +/- 14.3% of predicted [+/- SD]) with chronic respiratory insufficiency who randomly performed, on 2 consecutive days, a standardized 6-min walking test using two different modalities: a full-weight oxygen canister transported using a small wheeled cart and pulled by the patient (Aid modality) or full-weight oxygen canister carried on the patient's shoulder (No-Aid modality). MEASUREMENTS AND RESULTS: The distance walked, peak effort dyspnea, and leg fatigue scores as primary outcomes, and other cardiorespiratory parameters as secondary outcomes were recorded during both tests. A significant difference (p < 0.05) between the two tests occurred for all the measured outcomes in favor of the Aid modality. Most importantly, significant changes for distance (+ 43 m, p < 0.001), peak effort dyspnea (- 2.0 points, p < 0.001), leg fatigue (- 1.4 points, p < 0.001), as well as for mean and nadir oxygen saturation and heart rate with the Aid modality (but not with the No-Aid modality) were recorded in the subgroup of patients walking < 300 m at baseline. CONCLUSIONS: This study suggests that a simple walking aid may be helpful in COPD patients receiving long-term oxygen therapy, particularly in those with lower residual exercise capacity.