Morphometric Basis of the Sheet-Flow Concept of the Pulmonary Alveolar Microcirculation in the Cat

Sobin, Sidney S.; Tremer, Herta M.; Fung, Y. C.

doi:10.1161/01.res.26.3.397

Cited by 99 publications

(29 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The fourth observed pattern in this study was capillary recruitment occurring suddenly as capillary transmural pressure exceeded alveolar pressure, consistent with the idea of sheet flow described by Fung, Sobin, and colleagues (5,19). Godbey et al (9) showed that, as capillary transmural pressure exceeded alveolar pressure, the capillary networks tended to recruit as a sheet when alveoli were relatively undistended.…”

supporting

confidence: 88%

Heterogeneous capillary recruitment among adjoining alveoli

Baumgartner

Jaryszak

Peterson

et al. 2003

Journal of Applied Physiology

View full text Add to dashboard Cite

. Heterogeneous capillary recruitment among adjoining alveoli. J Appl Physiol 95: 469-476, 2003; 10.1152/ japplphysiol.01115.2002.-Pulmonary capillaries recruit when microvascular pressure is raised. The details of the relationship between recruitment and pressure, however, are controversial. There are data supporting 1) gradual homogeneous recruitment, 2) sudden and complete recruitment, and 3) heterogeneous recruitment. The present study was designed to determine whether alveolar capillary networks recruit in a variety of ways or whether one model predominates. In isolated, pump-perfused canine lung lobes, fields of six neighboring alveoli were recorded with video microscopy as pulmonary venous pressure was raised from 0 to 40 mmHg in 5-mmHg increments. The largest group of alveoli (42%) recruited gradually. Another group (33%) recruited suddenly (sheet flow). Half of the neighborhoods had at least one alveolus that paradoxically derecruited when pressure was increased, even though neighboring alveoli continued to recruit capillaries. At pulmonary venous pressures of 40 mmHg, 86% of the alveolar-capillary networks were not fully recruited. We conclude that the pattern of recruitment among neighboring alveoli is complex, is not homogeneous, and may not reach full recruitment, even under extreme pressures. pulmonary microcirculation; isolated perfused lung lobes; video microscopy; dogs PULMONARY CAPILLARIES ARE recruited with increasing microvascular pressure. Different investigators, however, have found different patterns of recruitment. With the introduction of the zone model, West et al. (31) showed that pulmonary blood flow increased down a vertical gradient as pulmonary arterial and venous pressures increased relative to alveolar pressure. Glazier and colleagues (6) studied red blood cell distributions in rapidly frozen lungs and showed that there was gradual, homogeneous recruitment as capillary pressure increased, especially in zone 2. Fung and Sobin (5) developed the sheet flow theory, which suggested that the entire capillary bed opened suddenly and completely as capillary transmural pressure exceeded alveolar pressure. This hypothesis was supported experimentally by Sobin et al. (19), who studied latex casts of the capillary bed. Godbey et al. (9) showed in excised lungs that sheet flow tended to occur at low airway pressure when alveoli were not highly distended, whereas gradual recruitment tended to occur in more distended alveoli. Although the zone and sheet flow models predict homogeneous recruitment, Warrell et al. (28), studying rapidly frozen lungs under zone 2 conditions, found an uneven distribution of capillary red blood cells within areas likely to have been supplied by a common arteriole. The scatter in the data of Godbey et al. as capillaries recruited suggests confirmation of the Warrell data, i.e., that capillary recruitment could be heterogeneous. West et al. (32), using an elegant computer model, deduced that recruitment in a network of resistors could be heterogeneous. Nevertheless...

show abstract

supporting

confidence: 88%

Heterogeneous capillary recruitment among adjoining alveoli

Baumgartner

Jaryszak

Peterson

et al. 2003

Journal of Applied Physiology

View full text Add to dashboard Cite

show abstract

“…The lung's unique hemodynamic properties are attributable to the so-called sheet structure of alveolar capillaries (8). According to this view, blood flow occurs not through tubular capillaries, as in systemic beds, but through two apposed sheet-like endothelial layers.…”

Section: Regulation Of the Properties Of The Alveolar-capillary Barrimentioning

confidence: 99%

Regulation and Repair of the Alveolar-Capillary Barrier in Acute Lung Injury

Bhattacharya

Matthay

2013

Annu. Rev. Physiol.

276

208

View full text Add to dashboard Cite

Considerable progress has been made in understanding the basic mechanisms that regulate fluid and protein exchange across the endothelial and epithelial barriers of the lung under both normal and pathological conditions. Clinically relevant lung injury occurs most commonly from severe viral and bacterial infections, aspiration syndromes, and severe shock. The mechanisms of lung injury have been identified in both experimental and clinical studies. Recovery from lung injury requires the reestablishment of an intact endothelial barrier and a functional alveolar epithelial barrier capable of secreting surfactant and removing alveolar edema fluid. Repair mechanisms include the participation of endogenous progenitor cells in strategically located niches in the lung. Novel treatment strategies include the possibility of cell-based therapy that may reduce the severity of lung injury and enhance lung repair.

show abstract

“…In its essence, this theory suggested (and the morphological studies supported) that the pulmonary microvasculature consisted of two thin sheets of endothelium through which the blood flowed. The only interruptions in this continuous sheet were posts of endothelial tissue that connected the membranes together (Sobin et al, 1970). This configuration would then give the vasculature a distensibility that was only limited by the large number of posts holding the two layers together and the prevailing alveolar pressures on either side of the membrane (Sobin et al, 1972).…”

Section: Effect Of Vascular Compliance On Pulmonary Blood Flowmentioning

confidence: 99%