Relationship between lung function,ventilation-perfusion inequality and extent of emphysema as assessed by high-resolution computed tomography

The development of the high-resolution computed tomography (HRCT) has improved the ability to detect and quantify emphysema in various groups of patients with chronic airflow obstruction (COPD). Significant correlations have previously been found between indices of air flow obstruction, hyperinflation, reduced diffusing capacity for carbon monoxide (DLCO), and the extent of emphysema (emph.%) assessed by HRCT. However, the relationship between emph.% and ventilation-perfusion (V(A)/Q) inequality in COPD is unknown. Twenty COPD patients with a mean forced expiratory volume in 1 s (FEV1) of 38.2 (+/- 15.5)% in percent of predicted value (%P), a mean PaO2 value of 9.6 (+/- 1.3) kPa, and a mean diffusing capacity of 43.6 (+/- 23.0)%P, were subjected to measurements by the multiple elimination inert gas technique (MIGET). The extent of emphysema was determined by HRCT at both full inspiration, emph.I(%) and at full expiration, emph.E(%), with a cut-off limit of -910 Hounsfield Units (HU) using the "Density Mask" method. The ventilation directed towards high V(A)/Q areas was 73 (+/- 10.2)% and the mean ventilation (V-mean) was elevated about three times compared to normal. The mean emph.(I)% and emph.(E) was 45.6 (+/- 16.9) and 32.7 (+/- 190)%, respectively. Significant correlations were shown between the emphysema extent and several lung function parameters, but no correlation was found between the emphysema extent and the V(A)/Q relationships or the blood gas values. Reduced DLCO%P correlated with less high V(A)/Q ventilation (r=0.73, P < 0.05) for the subgroup of COPD patients with DLCO(%P) less than 50% (n=12). Conclusions: In COPD patients, suffering from moderate to severe emphysema without severe blood gas impairment, no correlation was shown between the extent of emphysema, as assessed by HRCT, and the severity of ventilation-perfusion inequality. A substantial collateral ventilation in severe emphysema may be a mechanism that prevents a deterioration in V(A)/Q relationships and in blood gas levels.     

Tomographic and functional findings in severe COPD: comparison between the wood smoke-related and smoking-related disease

OBJECTIVE:

Wood smoke exposure is a risk factor for COPD. For a given degree of airway obstruction, the reduction in DLCO is smaller in individuals with wood smoke-related COPD than in those with smoking-related COPD, suggesting that there is less emphysema in the former. The objective of this study was to compare HRCT findings between women with wood smoke-related COPD and women with smoking-related COPD.

METHODS:

Twenty-two women with severe COPD (FEV₁/FVC ratio < 70% and FEV₁ < 50%) were divided into two groups: those with wood smoke-related COPD (n = 12) and those with smoking-related COPD (n = 10). The two groups were compared regarding emphysema scores and airway involvement (as determined by HRCT); and functional abnormalities-spirometry results, DLCO, alveolar volume (VA), the DLCO/VA ratio, lung volumes, and specific airway resistance (sRaw).

RESULTS:

There were no significant differences between the two groups in terms of FEV₁, sRaw, or lung hyperinflation. Decreases in DLCO and in the DLCO/VA ratio were greater in the smoking-related COPD group subjects, who also had higher emphysema scores, in comparison with the wood smoke-related COPD group subjects. In the wood smoke-related COPD group, HRCT scans showed no significant emphysema, the main findings being peribronchial thickening, bronchial dilation, and subsegmental atelectasis.

CONCLUSIONS:

Female patients with severe wood smoke-related COPD do not appear to develop emphysema, although they do show severe airway involvement. The reduction in DLCO and VA, with a normal DLCO/VA ratio, is probably due to severe bronchial obstruction and incomplete mixing of inspired gas during the determination of single-breath DLCO.     

Relationship between extent of pulmonary emphysema by high-resolution computed tomography and lung elastic recoil in patients with chronic obstructive pulmonary disease

We investigated the relationship between the extent of pulmonary emphysema, assessed by quantitative high-resolution computed tomography (HRCT), and lung mechanics in 24 patients with chronic obstructive pulmonary disease (COPD). The extent of emphysema was quantified as the relative lung area with CT numbers < -950 Hounsfield Units (HU). Patients with COPD had severe airflow obstruction (FEV(1) 35 +/- 15% pred) and severe reduction of CO diffusion constant (DCO/VA 37 +/- 19% pred). Maximal static elastic recoil pressure (Pst(max)) averaged 54 +/- 24% predicted, and the exponential constant K of pressure-volume curves was 258 +/- 116% predicted. Relative lung area with CT numbers < -950 HU averaged 21 +/- 11% (range 1 to 38%). It showed a highly significant negative correlation with DCO/VA (r = -0.84, p < 0.0001), a weak correlation with FEV(1)% predicted, and no correlation with either Pst(max) or constant K. A significant relationship was found between the natural logarithm of K and the full width at half maximum of the frequency distribution of CT numbers, taken as an index of the heterogeneity of lung density (r = 0.68, p < 0.0005). We conclude that currently used methods of assessing the extent of emphysema by HRCT closely reflect the reduction of CO diffusion constant, but cannot predict the elastic properties of the lung tissue.     

Comparison of single breath carbon monoxide diffusing capacity and pressure-volume curves in detecting emphysema

To evaluate the sensitivity of diffusing capacity (DLCO) and pressure-volume (P-V) curves in the detection of emphysema, these tests were compared with pathologic assessment of emphysema in patients undergoing lung resection for a localized tumor, and with the overall extent of emphysema as assessed by computed tomography (CT). The resected lung specimens were fixed in the inflated state and cut at 1-cm intervals in the horizontal plane. The pathologic extent of emphysema was quantitated by comparison with a standard reference panel of emphysema grading. The overall extent of emphysema on CT was assessed by a visual scoring system in a total of 55 patients, 19 undergoing lung resection and 36 not undergoing lung resection. Analysis of 37 patients by pathology scores revealed 18 with no or trivial emphysema (emphysema grades less than or equal to 5; mean grade, 2.2 +/- SD 2.6) and 19 with emphysema (grades greater than or equal to 10; mean grade, 33.2 +/- SD 24.2). Diffusing capacity, the ratio of DLCO to alveolar volume (DLCO/VA), maximal lung elastic recoil (PLmax), and lung elastic recoil at 90% of total lung capacity (PL90) were significantly different between the two groups, whereas K (the exponential constant describing the shape of the P-V curve) was not. The pathology grade of emphysema showed a significant correlation with (DLCO) (r = -0.53) and DLCO/VA (r = -0.55), which was greater than the correlation with PLmax (r = -0.42) and PL90 (r = -0.43).(ABSTRACT TRUNCATED AT 250 WORDS)     

各级慢性阻塞性肺疾病患者HRCT与肺功能相关性研究

目的研究不同级别慢性阻塞性肺疾病高分辨率CT（HRCT）异常定量变化,探讨HRCT定量评价与肺功能的相关性。方法将98例COPD患者依据GOLD方案分级,其中I级22例（第1组）,Ⅱ级26例（第2组）,Ⅲ级24例（第3组）,Ⅳ级26例（第4组）。观察所有人选者肺功能、血气分析、HRCT等检查,比较各组间变化及相关性。结果与第1组比较,第2～4组患者HRCT异常定量评分显著升高,比较差异均有统计学意义（P〈O．05）。而且各组间HRCT定量评价与肺功能分级有良好相关性。结论HRCT定量评价各级COPD患者是一项简单易行的临床方法。     

肺泡蛋白沉着症患者的肺功能与胸部分辨率CT的相关性

目的 探讨PAP患者的肺功能与高分辨率CT定量测量指标之间的相关性.方法 对2004至2007年在广州医学院第一附属医院呼吸疾病研究所住院的17例PAP患者(男10例,女7例,年龄15～51岁)进行肺通气及弥散功能检查和高分辨率CT检查,分析肺功能指标与高分辨率CT定量指标之间的相关性.比较其中6例行全肺肺泡灌洗治疗前、后的肺功能和高分辨率CT定量指标的变化.采用SPSS 13.0软件进行数据处理,结果 以x±s表示.结果 PAP患者的肺功能检查结果 以限制性通气功能障碍和弥散功能下降为主,弥散功能下降更为显著,DLCO占预计值%为(46±22)%,异常率为94.1%.肺功能检查结果 与高分辨率CT定量检查结果 之间存在一定的相关性,其中平均肺密度与FVC、肺重量与FEV1、肺含气容积比与呼气峰流量、DL.CO、DLCO与肺泡通气量比值(DLCO/VA)等指标的改变差异有统计学意义,(r值分别为-0.469、-0.482、0.511、0.659、0.692,均P<0.05),在所有指标中以肺含气容积比与DLCO/VA关系最为密切.6例肺泡灌洗术治疗的患者术后肺功能和高分辨率CT定量测量指标有所改善.结论 PAP的肺功能和胸部高分辨率CT改变之间存在相关性.2项检查同时进行可作为PAP患者随访的重要参考指标.     

Correlation of high-resolution CT, symptoms, and pulmonary function in patients during recovery from severe acute respiratory syndrome

STUDY OBJECTIVES: Little is known of the nature of the recovery period after severe acute respiratory syndrome (SARS) infection. We hypothesized that structural changes of the lung might correlate with symptoms and pulmonary function. To answer this question, we correlate findings of high-resolution CT (HRCT) with dyspnea scores and results of pulmonary function tests in patients during recovery from SARS. DESIGN: Retrospective follow-up cohort study. SETTING: University hospital. PATIENTS: Nineteen patients who recovered from SARS-related hospitalization. MEASUREMENTS: The study included HRCT scores (0 to 100), dyspnea scores (1 to 4), static and dynamic lung volumes, and diffusing capacity of the lung for carbon monoxide (DLCO). RESULTS: The interval between hospital discharge and HRCT study or functional assessment was 31.2 +/- 4.8 days (range, 25 to 38 days) [mean +/- SD]. All patients had HRCT abnormalities and were assigned to two groups: ground-glass opacity (GGO) only (n = 7, 36.8%) and GGO with fibrosis (GGO+F) [n = 12, 63.2%]. Most patients (16 of 19, 84.2%) had no zonal predominance. HRCT scores correlated well with dyspnea scores (r = 0.78, p < 0.01) and with a variety of pulmonary functional variables, with DLCO being the most significant (r = - 0.923, p < 0.001). Compared with the GGO group, the GGO+F group showed significantly lower FEV(1), FVC, total lung capacity, residual volume, and DLCO. CONCLUSIONS: HRCT findings correlate well with functional studies and clinical symptoms during recovery from SARS. Longer-term follow-up studies in a larger cohort of patients should be performed to investigate the clinical outcome of recovered SARS patients.     

慢性阻塞性肺疾病患者体质量指数与肺功能及HRCT气道重塑参数的相关性研究

目的探讨低体质量指数（bodymassindex,BMI）cOPD患者肺功能受损程度、临床及影像学特征。方法选取COPD急性加重期患者62例,根据BMI分为4组：低体重组（BMI％18．5kg／m2）、正常体重组（BMI18．5～23．9kg／m2）、超重组（BMI24．0H27．9kg／m2）、肥胖组（BMI≥28kg／m2）。所有患者进行慢性阻塞性肺疾病自我评估测试（COPDassessmenttest,CAT）问卷、肺功能检测及高分辨CT（highresolutionCT,HRcT）检查,并同时应用HRCT相关软件测定肺气肿评分、气道壁厚度及管腔面积等气道重塑指标。观察各组上述指标的变化,并研究其与BMI的相关性。结果①所有患者中低体重组患者12例,正常体重组患者30例,超重组患者7例,肥胖组患者13例,各组患者的年龄、性别、吸烟指数差异无统计学意义;②与正常体重、超重及肥胖患者比较,低体重患者FEV。％pred、MVV、Dt．co／VA％pred、FEV,／FVC均下降（P〈0．05）,而RV／TLc增高（P〈0．05）;③与正常体重、肥胖患者比较,低体重患者CAT评分增高（Pd0．05）;④与正常体重、超重及肥胖组患者比较,低体重组患者肺气肿评分高（Pd0．05）;⑤低体重患者管壁面积百分比（WA％pred）、壁厚与外径比率（TDR％pred）与各组间差异无统计学意义（P〉0．05）;⑥BMI与CAT评分、肺气肿评分、RV／TLC均呈负相关（r=-0．351,P〈0．05;r=-0．628,P〈0．05;r=-0．256,P〈0．05）,而与WA％pred、TDR％pred无相关性（P〉0．05）;BMI与FEV1／FVC、DLCO／VA％pred呈正相关（r=0．387,P〈0．05;r=0．549,P〈0．05）。结论低BMI的COPD患者肺气肿程度严重,通气及弥散功能明显下降,这对临床综合评估COPD病情的严重程度有一定帮助。     

Gas exchange alterations in patients with chronic obstructive lung disease

In a series of 23 patients with COPD, Wagner et al showed three distinct patterns of VA/Q distributions and a correlation between Burrows' clinical classification and the observed distribution patterns. Using the inert gas method, we studied 51 patients suffering from severe but stable COPD (FEV1 = 0.84 +/- 0.38 L; PaO2 = 58.5 +/- 10.5 mm Hg; PaCo2 = 48 +/- 6 mmHg; Ppa = 22 +/- 8 mmHg) breathing room air in a steady state. The H pattern (high mode of VA in high VA/Q) was found in 24 cases. There was an L pattern (Q mode in low VA/Q units) in nine cases and an HL (high-low) pattern in 16 cases (two patients were assigned another group). The analysis of the distribution data confirmed that VA/Q heterogeneity was the main factor underlying gas exchange disturbances in COPD. The PaO2 of the H subjects was higher than that of both HL (p less than 0.02) and L subjects. The true shunt value in the L group was significantly lower than in the H and HL groups. However, the relationship between clinical or functional aspects and distribution was not direct. The fraction of patients of H, HL, or (H + HL) types was nearly identical in the three clinical groups. The H pattern was found to be predominant in cases of COPD.     

Pulmonary function and high-resolution CT findings in patients with an inherited form of pulmonary fibrosis, Hermansky-Pudlak syndrome, due to mutations in HPS-1

OBJECTIVE: To describe and correlate pulmonary function and high-resolution CT (HRCT) scan scores in individuals with a high risk for development of pulmonary fibrosis, ie, Hermansky-Pudlak syndrome (HPS) patients with mutations in the HPS-1 gene. DESIGN: Cross-sectional analysis of consecutive, eligible patients. PATIENTS: Thirty-eight HPS inpatients at the National Institutes of Health Clinical Center with HPS-1 mutations. RESULTS: Thirty-seven patients were Puerto Rican and exhibited the typical 16-base pair (bp) duplication in exon 15 of HPS-1. One non-Puerto Rican was homozygous for a different mutation (intervening sequence 17 -2 A-->C) previously reported in the HPS-1 gene; he died at age 35 of pulmonary insufficiency. For the 23 patients who had pulmonary symptoms, the mean age of onset was 35 years. For all 38 patients (mean age, 37 +/- 2 years), the mean FVC was 71% of predicted; the mean FEV(1), 76%; mean total lung capacity (TLC), 72%; mean vital capacity (VC), 68%; and mean diffusing capacity of the lung for carbon monoxide (DLCO), 72%. When patients were grouped according to the extent of their reduction in FVC, the other four pulmonary function parameters followed the FVC. Seventeen patients had abnormal chest radiographs, and 31 (82%) had abnormal HRCT scans of the chest, for which a scoring system of 0 (normal) to 3 (severe fibrosis) is presented. The mean +/- SEM HRCT score for 38 patients was 1.30 +/- 0.17. HRCT scores correlated inversely with FVC and DLCO. CONCLUSIONS: Mutations in the HPS-1 gene, whether or not they involve the typical 16-bp duplication seen in Puerto Rican patients, are associated with fatal pulmonary fibrosis. In affected patients, the FVC, FEV(1), TLC, VC, and DLCO fall in concert, and this functional deficit correlates with HRCT scan evidence of progression of interstitial lung disease.     

Deleterious effect of nifedipine on pulmonary gas exchange in chronic obstructive pulmonary disease

Nifedipine was given, 20 mg sublingually, to 6 patients with pulmonary hypertension secondary to advanced chronic obstructive pulmonary disease, and its effects on hemodynamics, blood gases, lung mechanics, and the distribution of ventilation-perfusion ratios (VA/Q) were investigated. Systemic vasodilation was obtained, with a reduction in mean systemic arterial pressure and in systemic vascular resistance by 16 and 36%, respectively. Cardiac index increased by 29%. Pulmonary vascular resistance decreased by 28%, without changes in pulmonary arterial mean pressure. Arterial PO2 decreased from 52 +/- 4 to 47 +/- 3 mmHg (p less than 0.001). A deterioration in VA/Q matching could be demonstrated, with a redistribution of blood flow into the lungs by a diversion of 20% of total blood flow from units with normal VA/Q, between 0.23 to 3.0, to hypoxic units with low VA/Q between 0.19 to 0.009. These changes might be explained by a partial inhibition of hypoxic pulmonary vasoconstriction.     

Effect of bronchodilatation on single breath pulmonary uptake of carbon monoxide in chronic obstructive pulmonary disease

We studied 21 COPD patients in stable clinical conditions to evaluate whether changes in lung function induced by cumulative doses of salbutamol alter diffusing capacity for carbon monoxide (DL_CO), and whether this relates to the extent of emphysema as assessed by high resolution computed tomography (HRCT) quantitative analysis. Spirometry and DL_CO were measured before and after cumulative doses of inhaled salbutamol (from 200 μg to 1000 μg). Salbutamol caused significant increments of forced vital capacity (FVC), forced expiratory volume in one second (FEV₁), and flows at 30% of control FVC taken from both partial and maximal forced expiratory maneuvers. Functional residual capacity and residual volume were reduced, while total lung capacity did not change significantly. DL_CO increased progressively with the incremental doses of salbutamol, but this became significant only at the highest dose (1000 μg) and was independent of the extent of emphysema, as assessed by radiological parameters. No significant changes were observed in CO transfer factor (DLCO/VA) and alveolar volume (VA). The results suggest that changes in lung function induced by cumulative doses of inhaled salbutamol are associated with a slight but significant increase in DL_CO irrespective of the presence and extent of emphysema.     

Tumor necrosis factor-alpha serum levels,weight loss and tissue oxygenation in chronic obstructive pulmonary disease

Weight loss has been recognized as a feature of advanced emphysema and a factor of poor prognosis, but its mechanisms remain obscure. Studies have demonstrated high serum concentrations of TNF-a (cachexin) in chronic obstructive pulmonary disease (COPD) patients with emphysema. Pink puffers (PP) COPD patients have worse tissue oxygenation when compared with blue bloaters (BB) COPD patients. Consequently, PP patients would become cachectic, whereas BB patients with better tissue oxygenation would not. The aim of this study is to test the hypothesis that malnutrition in emphysema is a cytokine-mediated marker of chronic progressive tissue hypoxia. Thirty male COPD patients, without clinical or laboratory evidence of infection and severe air way obstruction (FEV1 < 1.5 l) were allocated: 16 as pink puffers (PP) and 14 as blue bloaters (BB). Lung function measurements included FEV1, FVC, RV, TLC, DLCO and arterial blood gases on room air. TNF-a serum levels were measured by immunoenzymic method (ELISA). Tissue oxygenation was assessed from oxygen delivery (DO2), PvO2 and oxygen extraction ratio (O2ER) obtained after right heart catheterization with Swan Ganz catheter. PP patients demonstrated lower DLCO and higher TLC, FRC and PaO2 from BB. We found that oxygen delivery was better in our BB than in PP patients (CI 2.9 +/- 0.2 vs 2.5 +/- 0.4 l/min/m2--P < 0.01, DO2 16.1 +/- 2.1 vs 13.1 +/- 0.2 ml/min/kg--P < 0.001) and the same was found for tissue oxygenation (PvO2 34.6 +/- 2.9 vs 31.2 +/- 3.8 mmHg--P < 0.01, O2ER 0.27 +/- 0.02 vs 0.34 +/- 0.06%--P < 0.001). The TNF-a values were higher in PP (31.3 +/- 26 pg/ml vs 15.2 +/- 9.9 pg/ml--P < 0.05) and their percent fat-free mass (%FFM) was 49.6 +/- 11.5 vs 42 +/- 8%--P < 0.001. We found that COPD patients with lower DO2 had increased TNF-a levels; but the correlations between TNF-a serum levels and PvO2 or O2ER were not statistically significant. TNF-a levels were elevated in PP patients with tissue hypoxia and may be a factor contributing to the weight loss of these patients.     

Abnormal peripheral blood T-lymphocyte subsets in a subgroup of patients with COPD

BACKGROUND: Smoking may induce changes in T-lymphocyte subsets in peripheral blood. Abnormalities of T-lymphocyte subsets in peripheral blood and in BAL fluid, and increased CD8+ T lymphocytes in the airways have been reported in patients with COPD. These findings suggest that T-lymphocyte abnormalities might be involved in the pathogenesis of airflow limitation in people who smoke. DESIGN: Cross-sectional study. SETTING: Outpatient pulmonary department of a university hospital. METHODS: To investigate this hypothesis, peripheral blood T-lymphocyte subsets were measured by flow cytometry using specific monoclonal antibodies in 20 healthy nonsmokers, 20 healthy smokers, and 20 smokers with stable COPD. No significant differences in the peripheral blood T-lymphocyte subsets were observed among the three groups. Because a previous study showed peripheral blood T-lymphocyte abnormalities in the subgroup of nonsmoking patients with COPD, we wanted to investigate what factors determine the subgroup of COPD with abnormal T-lymphocyte subsets. We tried to measure the relationship between T-lymphocyte subsets and physiologic indexes of pulmonary function tests in patients with COPD. The proportion of CD8+ T lymphocytes significantly correlated with diffusing capacity of the lung for carbon monoxide (DLCO) and DLCO per unit of alveolar volume (DLCO/VA), and CD4+/CD8+ ratio correlated with DLCO/VA. Therefore, we attempted to classify the patients with COPD into two subgroups on the basis of DLCO/VA: 10 COPD patients with low DLCO/VA (< 80% predicted) and 10 patients with normal DLCO/VA (> or = 80% predicted). RESULTS: The normal DLCO/VA subgroup had a significantly higher proportion of CD8+ T lymphocytes and a lower CD4+/CD8+ ratio than the healthy smokers or the low DLCO/VA subgroup. Moreover, FEV1/FVC significantly correlated with the CD4+/CD8+ ratio only in the normal DLCO/VA subgroup. CONCLUSION: These findings suggest that T-lymphocyte abnormalities might be involved in the pathogenesis of airflow limitation in a subgroup of patients with COPD, presumably with small airways disease, but not in all cases of COPD.     

Assessment of emphysema in COPD: a functional and radiologic study

OBJECTIVES: A combination of functional measurements reflecting a decrease in maximum flow, a degree of lung hyperinflation, the relationship between maximum inspiratory and expiratory flows, bronchodilator response, and diffusing capacity of the lung for carbon monoxide (DLCO) was used to quantify the extent of emphysema, as assessed by high-resolution CT (HRCT) scanning. DESIGN: Forced inspiratory and expiratory spirometry, lung volumes, reversibility test, and single-breath diffusing capacity were assessed before and after inhaling albuterol, 200 microg. Relationships between lung function variables and emphysema extent, as determined by HRCT scanning, were tested by univariate and multivariate analyses. SUBJECTS: Thirty-nine COPD outpatients with moderate-to-severe obstruction. MEASUREMENTS AND RESULTS: Emphysema extent, as assessed by HRCT scanning, ranged from 18 to 70%. All of the lung function parameters that were studied, except for the change in FEV1 percent predicted after salbutamol inhalation, correlated significantly with the extent of emphysema (r2 range, 0.19 to 0.44). Functional residual capacity, forced expiratory flow at 50% of FVC/forced inspiratory flow at 50% of FVC, DLCO/alveolar volume ratio, and bronchodilator-induced change in FEV1/FVC ratio were the only variables retained by stepwise multiple regression analysis. The multiple regression model explained 71% of the variability of emphysema extent measured by HRCT scanning. CONCLUSIONS: The combination of lung function measurements reflecting lung hyperinflation, bronchial collapsibility, lung diffusing capacity, and bronchodilator response provides a good estimate of the extent of emphysema, as evaluated by HRCT scanning. These data suggest that pulmonary function tests are useful in assessing and monitoring parenchymal damage in COPD patients.     

气胸对膜弥散量和肺毛细血管血量影响的临床研究

目的 探讨气胸患治疗前后肺膜弥散量和肺细血管血量对一氧化碳弥散量（Ｄ１ＣＯ）的影响,阐明肺复张后低氧血症的机制。方法 对２１例气胸患在治疗前和肺复张后１周进行肺通气功能,Ｄ１ＣＯ、Ｄｍ、Ｖｃ和动脉血气测定。结果 气胸时和肺复张后ＤＬＣＯ分别为（６４±４）％和（７１±４）％,Ｖｃ为（７０±５）％和（８０±６）％,动脑海因氧分压（ＰａＯ２）为（８３．７±２．３）ｍｍＨｇ和（８９．４±１．５）ｍｍｈ     

Ventilation-perfusion inequality in patients with non-alcoholic liver cirrhosis

Ventilation-perfusion relationships were studied in patients with non-alcoholic liver cirrhosis. Spirometry was essentially normal but the transfer factor of the lung (DLCO) was reduced by an average 34% of predicted. Arterial oxygen tension (PaO2) ranged from normal down to 6.9 kPa. Varying degrees of ventilation-perfusion (VA/Q) abnormalities (multiple inert gas elimination technique) were observed with increased dispersion of the perfusion distribution (log SDQ, 0.90; range 0.32-1.71; upper normal limit, 0.60) and the presence of both regions of low VA/Q ratios (between 0.1 and 0.005) (mean 4.1%; range 0-18.8%) and shunt (VA/Q ratios below 0.005) (mean 3.9%; range 0.19.8%). There was a close similarity between measured and calculated PaO2 in normoxaemic patients, but calculated values exceeded measured PaO2 in hypoxaemic patients. The difference between calculated and measured PaO2 correlated inversely to DLCO (r = 0.65, p less than 0.05). An inverse correlation was also noted between DLCO and the sum of shunt and low VA/Q regions (r = 0.87, p less than 0.001). It is concluded that hypoxaemia in non-alcoholic liver cirrhosis patients can be accounted for by intrapulmonary shunting and VA/Q mismatch, and possibly a "diffusion-perfusion" defect in patients with more severe gas exchange impairment.     

Gas exchange response to short-acting beta2-agonists in chronic obstructive pulmonary disease severe exacerbations

RATIONALE: Short-acting beta(2)-agonists are one of the mainstays of bronchodilator strategy for exacerbations of chronic obstructive pulmonary disease (COPD). The assessment of pulmonary gas exchange after salbutamol in COPD severe exacerbations remains unknown. OBJECTIVES: We investigated whether the effects of nebulized salbutamol during COPD severe exacerbations are associated with further deterioration of pulmonary gas exchange. METHODS: We examined patients with severe COPD when hospitalized for exacerbation (n = 9), and while in stable convalescence. MEASUREMENTS AND MAIN RESULTS: We assessed spirometry, arterial blood gases, systemic hemodynamics, and V/Q relationships 30 and 90 minutes after administration of 5.0 mg salbutamol. At exacerbation, compared with baseline, 30 minutes after salbutamol administration, cardiac output (Q) increased (from 6.5 +/- [SEM] 0.4 to 7.3 +/- 0.5 L . min(-1)) (p < 0.03) alone, without inducing changes in gas exchange indices. When in convalescence, compared with baseline, 30 minutes after salbutamol, there was an increase in Q (from 5.7 +/- 0.5 to 7.0 +/- 0.6 L . min(-1)) and Vo(2) (from 211 +/- 12 to 232 +/- 11 ml . min(-1)) (p < 0.002 each), whereas Pa(O(2)) decreased (from 71 +/- 4 to 63 +/- 3 mm Hg) and alveolar-arterial Po(2) difference increased due to increased perfusion of low-V/Q-ratio regions (from 4.5 +/- 2.6 to 9.6 +/- 4.1% of Q) (p < 0.05); Sa(O(2)) (93 +/- 2%) and Pa(CO(2)) (43 +/- 2 mm Hg) remained unchanged. This deleterious gas exchange response persisted at 90 minutes. CONCLUSIONS: At exacerbation, salbutamol does not aggravate pulmonary gas exchange abnormalities. When in convalescence, however, baseline lung function improvement was associated with a detrimental gas exchange response to salbutamol, resulting in further V/Q imbalance and small decreases in Pa(O(2)) compounded by small increases in Q and Vo(2).     

Mechanisms of hypoxemia in chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension is characterized by widespread central obstruction of the pulmonary arteries with organized thrombus and thereby differs substantially from other forms of pulmonary hypertension. We studied 25 patients using the multiple inert gas elimination technique to identify and quantitate the physiologic mechanisms of hypoxemia in this disorder. All patients had chronic obstruction of the central pulmonary arteries, which was demonstrated angiographically and later surgically confirmed. All patients but one were hypoxemic (PaO2 = 65 +/- 11 mm Hg, PaCO2 = 32 +/- 4 mm Hg, AaPO2 = 45 +/- 14 mm Hg), and all patients had pulmonary hypertension (mean Ppa = 45 +/- 11 mm Hg) with an elevated pulmonary vascular resistance (mean PVR = 1,000 +/- 791 dyne/s/cm5, normal less than 300). The cardiac index was reduced (1.7 +/- 0.6 L/min/m2), as was the P-vO2 (31 +/- 5 mm Hg). Inert gas studies revealed widened unimodal Va/Q distributions in 20 of 25 subjects, with a log standard deviation of 1.01 +/- 0.32 (upper limit of normal, 0.6; ages 20 to 40), shunt = 0.03 +/- 0.05 of cardiac output, and dead space of 3.4 +/- 1.1 ml/kg (upper limit of normal, 2.9). The VD/VT ratio was 0.51 +/- 0.10. No low (VA/Q less than 0.1) or high (VA/Q greater than 10.0) regions were present, and no evidence for diffusion limitation of O2 transfer at rest was found. The low cardiac output and resulting low P-VO2 were responsible for approximately 33% of the increased AaPO2. The magnitude of the VA/Q abnormality correlated poorly with the PVR, the mean Ppa, or the magnitude of vascular obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)     

肺纤维化合并肺气肿综合征八例并文献复习

目的 探讨肺纤维化合并肺气肿(CPFE)综合征的临床、肺功能及影像学特点.方法 结合文献对北京协和医院2006-2009年确诊的8例CPFE综合征患者的临床、肺功能及影像学特点进行分析.结果 8例均为男性,7例为吸烟者,年龄59～75岁,中位数为65岁,7例有活动后呼吸困难,4例有杵状指,6例有双下肺爆裂音.肺功能结果[中位数(范围)]:FVC占预计值%为73%(51%-92%),FEV1/FVC为76%(60%-86%),肺总量占预计值%为80%(59%～114%),DLCO占预计值%为44%(16%-65%).胸部高分辨率CT示双上肺为主的肺气肿及肺大疱,双下肺为主的网格影、蜂窝肺及牵张性支气管扩张.其中6例有肺动脉高压,肺动脉收缩压的中位数为49 mm Hg(1 mm Hg=0.133 kPa),范围为35-101 mm Hg.结论 胸部高分辨率CT是诊断肺纤维化合并肺气肿综合征的重要手段,其特点为同时存在上肺野肺气肿和下肺野纤维化.肺功能表现为肺容积相对正常而弥散能力显著下降,是该综合征的突出特点.肺动脉高压发生率较高.肺纤维化合并肺气肿综合征能否作为一种独立的综合征,其发病机制、治疗及预后仍有待进一步研究.