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The pulmonary circulation
412
TUBERCLE
T U B E R C L E. JUNE, 1932. .
.
.
.
.
.
.
.
The Pulmonary Circulation. THERE has always been much speculation as to the mechanism of the pulmonary circulation. It is well-known that there is an extensive system of wide eapillaries offering very little resistance to the flow of blood and that these capillaries vary passively in size according to different conditions--hence the variation in volume of the lung. At the height of inspiration the blood contained in the lungs has been estimated at about one-twelfth, whereas during expiration it falls to one-fifteenth to one-eighteenth [1]. As to the vasomotor control there is much difference of opinion. According to Anrep, the coronary circulation must also be taken into account in considering the volume of pulmonary blood ; any. increase of the coronary circulation is believed to cause a corresponding increase in the amount of blood ejected by the right ventricle into the pulmonary artery. In an excellent new American journal,
The
Journal
of
Thoracic Surgery,
Doctors Mathes, Holman and Reiehert [2] have made a study of the bronchial, pulmonary and lymphatic circulations of the lung under various pathologic conditions, experimentally produced, which throw light on these questions. They stress the point that the circulation in the lungs is unique, in that a comparatively small amount of arterial blood for the nutrition of all the pulmonary structures is supplied through the bronchial artery under normal systemic pressure, and a relatively large quantity of venous blood for oxygenation is supplied through the pulmonary artery at approximately a third of the normal systemic pressure. The exact r61e played by these two vascular systems in the reaction of pulmonary tissues to disease and to pulmonary embolism has hitherto received little attention. The studies carried out by the authors were made upon dogs, by
the
[ J u n e , 1932
injection of the vessels with a suspension of 20 per cent. bismuth oxychloride in 11 per cent. acacia, which fills up the vessels without ineluding the capillary bed. It must be borne in mind that the pulmonary artery supplies only the respiratory epithelium of the terminal alveoli. I t is an end artery in the sense that it has no anastomoses proximal to the capillary bed. The bronchial artery supplies the rest oi the lung. Large anastomoses connect its branches before they enter each lobe and form a coarse-meshed network round each bronchus within the lobe. The bronchial artery extends only to the ductus alveolares, when it breaks up into a capillary network. The blood is returned by the pulmonary vein. Near the hilum bronchial veins returning blood from the bronchial arteries are found, but attempts to demonstrate them by injection have repeatedly failed. Careful dissection of the vessels showed that, unlike the puhnonary veins, they contained competent valves which prevent injection. No precapillary connections between the bronchial and pulmonary arteries were found, bug a definite capillary communication between the two arterial systems was established. The authors quoted Karsner to the effect that with normal pressure relationships (140 mm. Hg bronchial arteries, 40 mm. H g pulmonary arteries), there is practically no mixture of the blood of the two systems. Only when the pressure in the one system or the other was reduced to zero did the blood flow from one of high pressure to the one of no pressure. The pulmonary vein contains no valves and has no anastomoses of its larger branches, though there are capillary an astomoses. The writers then went on to investigate the circulation in broncho-pneumonia and atelectasis, from material obtained largely from dogs suffering from distemper. Some of these animals died of broncho-pneumonia ; others were killed earlier in the disease. The distemper was found to begin with an acute sinusitis and upper respiratory tract infection, which was followed by broncho-pneumonia, varying in extent
J u n e , 1932]
Pur,MoN:xaY CIRCULAT[ON
from areas of patchy consolidation to a massive consolidation of the entire lung. All these broncho-pneumonic lungs, when injected, showed certain definR.e constant features. I n pneumonia the bronchial artery to the involved lobe became definitely dilated, the pulmonary artery failed ~o fill completely in the precapillary area, due to thrombosis or occlusion by pressure from the surrounding (:edema. In atelectasis, the authors found that~ the bronchial artery and the pulmonary artery were normal when the atelectasis remained sterile, but that when pneumonia was present in the ateleetatie lobe, dilatation of the bronchial artery and incomplete filling of the pulmonary artery in its precapillary bed occurred. In embolism, occlusion of a branch of the pulmonary artery to the lobe led to marked dilatation of the bronchial artery with pulmonary artery
BOOK
NOTICES
413
filling through it. If the embolus was sterile there was little change, whereas if the embolus was infected, pneumonia, hmmorrhagic infarct, abscess formation and h~emorrhagic consolidation resulted. I n these cases the bronchial artery was markedly dilated and was an important factor in repair. It was also found that ligature of the pulmonary artery to the lobe caused only slight shrinkage of the lobe, with the bronchial artery maintaining the blood-supply. This paper throws much light on some of the puzzling phenomena of pulmonary morbid anatomy. REFERENCES. [I] STAaLING, E.H. " Principles of Human Physiology," 4th Edition, London, 1926.
[c2] MATHES, M. E., HOL]~IAN, E., and REICHERT, F., L. Jo'ltT'l~. ~'horacic Surg. ,
AND
1932, i, 339.
ABSTRACTS.
whereas the number of deaths among an equal number oi persons belonging D~deligheten blandt Sanatoriebe- to the population as a whole would only handlede TuberkulOse. :By F. Lunge- have been 88"1 in the same period. In Nielsen. Oslo: Jacob Dybwad. 1931. this respect, therefore, the ratio of the Pp. 49. sanatorium patient to an average repreGrefsen is a public sanatorium near sentative of the community was as 1'2 to 1. Striking differences were, of course, Oslo, and here, in the period 1910-1916, 887 men and 1,065 women were dis- observed in the various Gerhardt-Turban charged. Only 9~6 could subsequently stages, and according as the patients not be traced. The study of this material were or were not sputum-positive. For was completed at the end of 1921, and first-stage patients the ratio of actual to in 1924 Dr. Sofie Tilliseh published her calculated deaths was as 2"7 to 1. For findings. In response to requests for a the second and third stages the corresstatistical study of this material on ponding figures were 7"5 and 27'5 modern actuarial lines, and with the respectively. Table 5 gives the histories of first-stage financial support of the Nansen Fund, Dr. Lange-Nielsen has now made a patients who on discharge were apparently cured or improved. The most concompletely new digest of it. One of the most striking and disap- spicuous feature of this table is the low pointing results of this study is the mortality in the first year after discharge, calculation that the expectation of life and the rapid increase of the mortality of these discharged patients was, on which reached its maximum in the the average, no better than that of the second year. After three years the male population of Norway at the age mortality seems to have settled to about of 80. Yet, the average age of these twice the normal. In the absence of patients was about 28 years at the time an equally large group of tuberculous of discharge. There were altogether patients living under similar conditions, but not receiving sanatorium treatment, 1,056 deaths among these patients,
Book Noticea.
TUBERCLE
T U B E R C L E. JUNE, 1932. .
.
.
.
.
.
.
.
The Pulmonary Circulation. THERE has always been much speculation as to the mechanism of the pulmonary circulation. It is well-known that there is an extensive system of wide eapillaries offering very little resistance to the flow of blood and that these capillaries vary passively in size according to different conditions--hence the variation in volume of the lung. At the height of inspiration the blood contained in the lungs has been estimated at about one-twelfth, whereas during expiration it falls to one-fifteenth to one-eighteenth [1]. As to the vasomotor control there is much difference of opinion. According to Anrep, the coronary circulation must also be taken into account in considering the volume of pulmonary blood ; any. increase of the coronary circulation is believed to cause a corresponding increase in the amount of blood ejected by the right ventricle into the pulmonary artery. In an excellent new American journal,
The
Journal
of
Thoracic Surgery,
Doctors Mathes, Holman and Reiehert [2] have made a study of the bronchial, pulmonary and lymphatic circulations of the lung under various pathologic conditions, experimentally produced, which throw light on these questions. They stress the point that the circulation in the lungs is unique, in that a comparatively small amount of arterial blood for the nutrition of all the pulmonary structures is supplied through the bronchial artery under normal systemic pressure, and a relatively large quantity of venous blood for oxygenation is supplied through the pulmonary artery at approximately a third of the normal systemic pressure. The exact r61e played by these two vascular systems in the reaction of pulmonary tissues to disease and to pulmonary embolism has hitherto received little attention. The studies carried out by the authors were made upon dogs, by
the
[ J u n e , 1932
injection of the vessels with a suspension of 20 per cent. bismuth oxychloride in 11 per cent. acacia, which fills up the vessels without ineluding the capillary bed. It must be borne in mind that the pulmonary artery supplies only the respiratory epithelium of the terminal alveoli. I t is an end artery in the sense that it has no anastomoses proximal to the capillary bed. The bronchial artery supplies the rest oi the lung. Large anastomoses connect its branches before they enter each lobe and form a coarse-meshed network round each bronchus within the lobe. The bronchial artery extends only to the ductus alveolares, when it breaks up into a capillary network. The blood is returned by the pulmonary vein. Near the hilum bronchial veins returning blood from the bronchial arteries are found, but attempts to demonstrate them by injection have repeatedly failed. Careful dissection of the vessels showed that, unlike the puhnonary veins, they contained competent valves which prevent injection. No precapillary connections between the bronchial and pulmonary arteries were found, bug a definite capillary communication between the two arterial systems was established. The authors quoted Karsner to the effect that with normal pressure relationships (140 mm. Hg bronchial arteries, 40 mm. H g pulmonary arteries), there is practically no mixture of the blood of the two systems. Only when the pressure in the one system or the other was reduced to zero did the blood flow from one of high pressure to the one of no pressure. The pulmonary vein contains no valves and has no anastomoses of its larger branches, though there are capillary an astomoses. The writers then went on to investigate the circulation in broncho-pneumonia and atelectasis, from material obtained largely from dogs suffering from distemper. Some of these animals died of broncho-pneumonia ; others were killed earlier in the disease. The distemper was found to begin with an acute sinusitis and upper respiratory tract infection, which was followed by broncho-pneumonia, varying in extent
J u n e , 1932]
Pur,MoN:xaY CIRCULAT[ON
from areas of patchy consolidation to a massive consolidation of the entire lung. All these broncho-pneumonic lungs, when injected, showed certain definR.e constant features. I n pneumonia the bronchial artery to the involved lobe became definitely dilated, the pulmonary artery failed ~o fill completely in the precapillary area, due to thrombosis or occlusion by pressure from the surrounding (:edema. In atelectasis, the authors found that~ the bronchial artery and the pulmonary artery were normal when the atelectasis remained sterile, but that when pneumonia was present in the ateleetatie lobe, dilatation of the bronchial artery and incomplete filling of the pulmonary artery in its precapillary bed occurred. In embolism, occlusion of a branch of the pulmonary artery to the lobe led to marked dilatation of the bronchial artery with pulmonary artery
BOOK
NOTICES
413
filling through it. If the embolus was sterile there was little change, whereas if the embolus was infected, pneumonia, hmmorrhagic infarct, abscess formation and h~emorrhagic consolidation resulted. I n these cases the bronchial artery was markedly dilated and was an important factor in repair. It was also found that ligature of the pulmonary artery to the lobe caused only slight shrinkage of the lobe, with the bronchial artery maintaining the blood-supply. This paper throws much light on some of the puzzling phenomena of pulmonary morbid anatomy. REFERENCES. [I] STAaLING, E.H. " Principles of Human Physiology," 4th Edition, London, 1926.
[c2] MATHES, M. E., HOL]~IAN, E., and REICHERT, F., L. Jo'ltT'l~. ~'horacic Surg. ,
AND
1932, i, 339.
ABSTRACTS.
whereas the number of deaths among an equal number oi persons belonging D~deligheten blandt Sanatoriebe- to the population as a whole would only handlede TuberkulOse. :By F. Lunge- have been 88"1 in the same period. In Nielsen. Oslo: Jacob Dybwad. 1931. this respect, therefore, the ratio of the Pp. 49. sanatorium patient to an average repreGrefsen is a public sanatorium near sentative of the community was as 1'2 to 1. Striking differences were, of course, Oslo, and here, in the period 1910-1916, 887 men and 1,065 women were dis- observed in the various Gerhardt-Turban charged. Only 9~6 could subsequently stages, and according as the patients not be traced. The study of this material were or were not sputum-positive. For was completed at the end of 1921, and first-stage patients the ratio of actual to in 1924 Dr. Sofie Tilliseh published her calculated deaths was as 2"7 to 1. For findings. In response to requests for a the second and third stages the corresstatistical study of this material on ponding figures were 7"5 and 27'5 modern actuarial lines, and with the respectively. Table 5 gives the histories of first-stage financial support of the Nansen Fund, Dr. Lange-Nielsen has now made a patients who on discharge were apparently cured or improved. The most concompletely new digest of it. One of the most striking and disap- spicuous feature of this table is the low pointing results of this study is the mortality in the first year after discharge, calculation that the expectation of life and the rapid increase of the mortality of these discharged patients was, on which reached its maximum in the the average, no better than that of the second year. After three years the male population of Norway at the age mortality seems to have settled to about of 80. Yet, the average age of these twice the normal. In the absence of patients was about 28 years at the time an equally large group of tuberculous of discharge. There were altogether patients living under similar conditions, but not receiving sanatorium treatment, 1,056 deaths among these patients,
Book Noticea.