The senile lung. Comparison with normal and emphysematous lungs. 1. Structural aspects.

As part of a study of the structural-functional correlations of excised human lungs obtained at autopsy, the parenchyma and peripheral airways were examined by means of morphometric techniques. Among the 30 lungs characterized by the absence of fibrosis, ten differed from the normal and emphysematous lungs by a homogeneous dilatation of the airspaces, in excess of the dimensions predicted on the basis of age. Study of the standard deviations of the mean linear intercepts showed that the airspace dilatation was more regular than in emphysematous lungs; in addition, there was no clear-cut destruction, as estimated from the number of alveolar attachments. These lungs were characterized in addition by an increased thickening of alveolar septa, without inflammation or fibrosis, normal size of the diameter, and reduced density of the membranous bronchioles. Since these lungs were from people older than 60 years, it is assumed that they represent cases of exaggerated airspace enlargement of the aging lung, differing from emphysema by the absence of destruction of alveolar walls. The term "senile lung" is proposed or this condition.     

Stress-strain characteristics of normal and emphysematous hamster lung strips.

A simple mathematical model of the one dimensional, stress-strain behavior of hamster lung tissue based on strain energy considerations was tested in degassed, uniaxially stretched strips obtained from normal and emphysematous hamster lungs cycled in saline. The relationship between Eulerian stress (sigma) and extension ratio (lambda) was found to take the form sigma = (lambda 2-1/lambda) x f(lambda) where the function f(lambda) was experimentally determined. Stress in six normal and five emphysematous strips was calculated by dividing the tension at each stretch increment by the strip cross-sectional area. Plotting sigma lambda/(lambda 2-1) versus a function of the form e eta lambda yielded a linear expression for f(lambda), me eta lambda + b, where n = 2. The complete stress-strain behavior of hamster lung strip tissue could then be expressed as a simple function of lambda over a range of lambda = 1.0-2.0: sigma = (lambda 2-1/lambda)(me2 lambda+b) The values of the constants m and b depend solely upon the mechanical properties of the elastic and collagen fiber networks in these atelectatic, saline cycled lung strips. The slope m = 0.151, and the intercept b = 0.416 in normal strips (r = 0.98). In emphysematous strips m = 0.016 and b = -0.199 (r = 0.82). Given the smaller m found for emphysematous strips, less strain energy accumulated with increasing stretch and did not even begin in these strips until lambda = 1.3. Further, the fit of the equation to the data was not as good for emphysematous as for normal strips. We conclude that the above equation adequately describes the stress-strain properties of normal hamster lung strips tissue but is not as good in emphysematous strips where the disease is patchy.     

Elastin content of normal and emphysematous lung parenchyma

Elastin destruction has been recognized as a crucial factor in the development of experimental pulmonary emphysema. However, no consistent alterations in lung elastin have as yet been demonstrated in human subjects with diffuse panacinar emphysema. In this study elastin content was measured in pulmonary parenchyma obtained by surgical biopsy and postmortem from eight patients with clinical, physiologic and morphologic criteria for panacinar emphysema, and postmortem from six normal adults. Concentrations of the elastin-specific amino acids, desmosine and isodesmosine, were determined both in the crude connective tissue of lung parenchyma and separately in elastin isolated by a modification of the Lansing method. Elastin proportions were then expressed as percent of lung parenchymal crude connective tissue. In lungs of six normal control subjects mean elastin was 30.5 percent standard deviation (SD) ± 3.69 (range 25.1 to 35.0 percent). In five patients the proportions of lung elastin were all below control: mean 12.1 percent SD ± 3.7 (range 9.0 to 17.5 percent). Three patients of this group had Pi phenotype MM; one had ZZ and one had MZ. In three additional patients (one with Pi MZ; two with Pi MM), all of whom had received glucocorticoid therapy (21 months to nine years), elastin proportions were similar to those observed in normal subjects: mean 36.8 percent SD ± 5.98 (range 31.7 to 43.4 percent). The amino acid composition of isolated elastin did not differ significantly between any of the groups. Results demonstrate reduced proportions of lung elastin in pulmonary emphysema except in patients treated with glucocorticoids which may decrease collagen synthesis and increase the relative proportions of elastin.     

Glycosaminoglycans in emphysematous and fibrotic hamster lungs

Amounts and distributions of glycosaminoglycans were measured in lungs obtained from hamsters treated intratracheally 21 to 30 days previously with either saline, purified pancreatic elastase, or bleomycin. Normal hamster lungs contained 150 to 200 micrograms glycosaminoglycans per lung. Lungs made fibrotic by bleomycin contained significantly more glycosaminoglycans per lung than saline-treated control lungs; this increase was equally distributed among all glycosaminoglycan subtypes. Emphysematous lungs also contained more glycosaminoglycans than saline control lungs; this increase was less than that of fibrotic lungs and was limited to the dermatan sulfate subtype. The latter was increased in emphysematous lungs when expressed as a percentage of total glycosaminoglycans. In these hamster models of lung diseases that affect the connective tissue framework of the lungs, changes in lung glycosaminoglycans accompany changes in the other connective tissue components.     

The "destructive index" in nonemphysematous and emphysematous lungs. Morphologic observations and correlation with function

We examined the relationship of the newly described "Destructive Index" (DI) to emphysema using nine nonemphysematous and 13 emphysematous lungs obtained at autopsy. The amount of emphysema was assessed by the panel method (emphysema grade, EG) and measurement of the mean linear intercept (Lm). The DI depends on three components--alveolar wall/duct disruption, DId; alveolar fibrosis, DIf; and classic emphysema, DIe. DIf was a minor component in our series. The mean DI was 5.8 +/- 2.5, 10.9 +/- 3.9, and 55.7 +/- 7.0% (+/- 1 SEM) in the nonemphysematous (panel grade EG = 0), mild (0 less than EG less than or equal to 25), and moderate to severe (30 less than or equal to EG less than or equal to 60) emphysematous lungs, respectively. The increase in the DI in mild emphysema did not reach significant levels (p less than 0.2). The mean DId was 5.6 +/- 2.5, 10.0 +/- 4.0, and 12.8 +/- 3.9% in the above categories, and the DId in mild emphysema did not differ significantly from that of the nonemphysematous lungs. Lm showed a similar trend and alveolar disruption did not precede airspace enlargement, rather both changes appeared to advance in parallel. The DI correlated closely with EG (r = 0.83, p less than 0.01), but this was due to the component of DIe. The DIe increased steeply in the lungs with EG greater than or equal to 30.(ABSTRACT TRUNCATED AT 250 WORDS)     

Giant emphysematous bullae of the lung.

Emphysematous bullae may at times assume large proportions. We report a case of symptomatic giant bullae in a female which were removed surgically. The relevant literature has also been reviewed.     

Effects of end-expiratory lung volume on lung mechanics in normal and edematous lungs

This study determined the effects of end-expiratory pressures (EEP) and alterations in end-expiratory lung volume (EELV) on lung compliance (CL) and pulmonary resistance to gas flow (RP) in 20 cats with normal and edematous lungs. EELV was varied using EEP ranging from -8 to +10 cm H2O. Negative EEP was used to decrease EELV of the healthy lung causing CL to decrease and RP to increase. Positive EEP in the healthy lung also caused CL to decrease but did not significantly affect RP. After inducing pulmonary edema using alloxan, functional residual capacity (FRC) decreased 38%, CL decreased 66% and RP increased 106% (p less than 0.001). An EEP of 4 cm H2O returned EELV to normal FRC levels and produced maximum values for CL. Increases in EEP to 4 cm H2O also caused decreases in RP in the edematous lungs but further increase did not cause significant changes in RP. These results show that (1) relatively low levels of EEP returned EELV to normal FRC levels in alloxan-induced pulmonary edema, and (2) optimal lung mechanics were obtained when EELV was equal to or slightly above normal FRC values in both healthy and edematous lungs.     

Comparison of high-frequency oscillatory ventilation and high-frequency jet ventilation in cats with normal lungs

Four adult cats received alternating high-frequency oscillatory ventilation (HFOV) and high-frequency jet ventilation (HFJV) at equivalent proximal airway pressures. Physiologic measurements were made before and after each ventilator change. Proximal airway pressures were then adjusted as necessary to reestablish normal pH and PaCO2 values. Aortic, pulmonary artery, and central venous pressures were monitored. Cardiac outputs were measured. Pulmonary and systemic vascular resistance, intrapulmonary shunt, and alveolar-arterial oxygen gradient were determined. Following the change from HFOV to HFJV at similar proximal airway pressures, HFJV always produced higher pH values (P less than 0.0001), higher PaO2 values (P less than 0.05), lower PaCO2 values (P less than 0.0001), as well as higher cardiac outputs (P less than 0.01), lower pulmonary artery pressures (P less than 0.001), and lower pulmonary vascular resistances (P less than 0.001). Following the reciprocal crossover, from HFJV to HFOV, HFJV pH values were again higher (P less than 0.001), and PaCO2 values were again lower (P less than 0.001). A comparison of HFOV and HFJV at similar pH and PaCO2 values showed that HFOV consistently required higher peak inspiratory pressures (P less than 0.001), higher mean airway pressure (P less than 0.001), and higher pressure wave amplitudes (P less than 0.001). Under the circumstances of this study, HFJV produced better gas exchange at lower proximal airway pressures.     

Five cases of lung cancer with emphysematous bullae]

In bullous lung disease the incidence of lung cancer occurs with significant frequency among the general population, but lung cancer with a spontaneous pneumothorax is rare, and the prognosis is frequently poor. Five cases of lung cancer with emphysematous bullae of the lung were reported. In 4 cases there were simultaneous occurrences of lung cancer and pneumothorax. The patients were 49-, 36- and 68-year-old men and a 72-year-old woman, and the initial sign in all was pneumothorax. Histologically, there was one squamous cell carcinoma, two poorly differentiated adenocarcinomas and one well-differentiated adenocarcinoma. In the other case, giant emphysematous bullae were diagnosed in a 51-year-old man and were treated by bullectomy. Histological examination incidentally revealed a small well-differentiated adenocarcinoma, which extended along the wall of the largest right bulla. About 18 months later, the patient was found to have poorly differentiated adenocarcinoma of the left lung, which was treated surgically. We should always be careful of lung cancer associated with emphysematous bullae and pneumothorax.     

保护性肺通气对肺功能正常患者呼吸力学的影响

目的 探讨保护性肺通气对肺功能正常的患者呼吸力学的影响.方法 将我院2010年6月至2011年3月收治的100例腹部手术的患者分为研究组和对照组,每组50例,对照组采用常规机械通气,研究组采用保护性肺通气模式,比较两组患者的呼吸力学参数的改变.结果 研究组气道峰压(Ppeak)、气道平均压(Pmean),呼气末二氧化碳分压(PETCO2),呼吸系统总顺应性(Crs)显著高于对照组,P<0.05.呼吸系统总阻力(Rrs)显著低于对照组,P<0.05.结论 与常规机械通气模式对比,采用保护性肺通气,患者的Ppeak、Pmean,PETCO2、Crs显著提高,Rrs显著降低.