Pulmonary blood flow and tissue volume: model analysis of rebreathing estimation methods

1983 ◽  
Vol 55 (1) ◽  
pp. 205-211 ◽  
Author(s):  
G. M. Burma ◽  
G. M. Saidel
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Breathing Pattern ◽  
Estimation Methods ◽  
Balance Model ◽  
Mass Balance Model ◽  
Volume Model ◽  
Dynamic Mass ◽  
Ventilation And Perfusion ◽  
Rebreathing Methods

As the basis for comparing rebreathing methods of estimating pulmonary blood flow (Q) and tissue-capillary volume (Vtc), we use a dynamic mass-balance model for gas species having different physicochemical properties (e.g., He, CO, C2H2). The model accounts for the effects of ventilation and perfusion inhomogeneities, breathing pattern variation, lung and rebreathing-bag volumes, and recirculation. Also, we examine the variability of the estimates caused by random error. In addition to analyzing two well-known methods, we show how an appropriate synthesis of these methods can lead to improved estimates.

Pulmonary Blood Flow Redistribution with Low Levels of Positive End-expiratory Pressure 

1998 ◽  
Vol 88 (5) ◽  
pp. 1291-1299 ◽  
Author(s):  
Harry J. Kallas ◽  
Karen B. Domino ◽  
Robb W. Glenny ◽  
Emily A. Anderson ◽  
Michael P. Hlastala
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Zone Model ◽  
Structural Factors ◽  
Positive End Expiratory Pressure ◽  
Mechanically Ventilated ◽  
Anesthetized Dogs ◽  
Low Levels ◽  
Ventilation And Perfusion ◽  
Lung Zone

Background Recent studies have questioned the importance of the gravitational model of pulmonary perfusion. Because low levels of positive end-expiratory pressure (PEEP) are commonly used during anesthesia, the authors studied the distribution of pulmonary blood flow with low levels of PEEP using a high spatial resolution technique. They hypothesized that if hydrostatic factors were important in the distribution of pulmonary blood flow, PEEP would redistribute flow to more dependent lung regions. Methods The effects of zero cm H2O PEEP and 5 cm H2O PEEP on pulmonary gas exchange were studied using the multiple inert gas elimination technique; the distribution of pulmonary blood flow, using fluorescent-labeled microspheres, was also investigated in mechanically ventilated, pentobarbital-anesthetized dogs. The lungs were removed, cleared of blood, dried at total lung capacity, and then cubed to obtain approximately 1,000 small pieces of lung (approximately 1.7 cm3). Results Positive end-expiratory pressure increased the partial pressure of oxygen by 6 +/- 2 mmHg (P < 0.05) and reduced all measures of ventilation and perfusion heterogeneity (P < 0.05). By reducing flow to nondependent ventral lung regions and increasing flow to dependent dorsal lung regions, PEEP increased (P < 0.05) the dorsal-to-ventral gradient. Redistribution of blood flow with PEEP accounted for 7 +/- 3%, whereas structural factors accounted for 93 +/- 3% of the total variance in blood flow. Conclusions The increase in dependent-to-nondependent gradient with PEEP is partially consistent with the gravitationally based lung zone model. However, the results emphasize the greater importance of anatomic factors in determining the distribution of pulmonary blood flow.

A modified breathing pattern improves the performance of a continuous capnodynamic method for estimation of effective pulmonary blood flow

2016 ◽  
Vol 31 (4) ◽  
pp. 717-725 ◽  
Author(s):  
Caroline Hällsjö Sander ◽  
Thorir Sigmundsson ◽  
Magnus Hallbäck ◽  
Fernando Suarez Sipmann ◽  
Mats Wallin ◽  
...  
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Breathing Pattern

Dynamic mass balance model for mercury in the St. Lawrence River near Cornwall, Ontario, Canada

2014 ◽  
Vol 500-501 ◽  
pp. 131-138 ◽  
Author(s):  
Charlotte R. Lessard ◽  
Alexandre J. Poulain ◽  
Jeffrey J. Ridal ◽  
Jules M. Blais
Keyword(s):  
Mass Balance ◽  
Balance Model ◽  
Mass Balance Model ◽  
Dynamic Mass ◽  
St Lawrence River

Influence of Anaesthesia on the Regional Distribution of Perfusion and Ventilation in the Lung

1970 ◽  
Vol 38 (4) ◽  
pp. 451-460 ◽  
Author(s):  
G. H. Hulands ◽  
R. Greene ◽  
L. D. Iliff ◽  
J. F. Nunn
Keyword(s):  
Blood Flow ◽  
Lung Volume ◽  
Pulmonary Blood Flow ◽  
Artificial Ventilation ◽  
Pulmonary Ventilation ◽  
Regional Distribution ◽  
Residual Capacity ◽  
Arterial Po2 ◽  
Ventilation And Perfusion ◽  
Perfusion Unit

1. Distribution of lung volume, pulmonary ventilation and perfusion were studied in supine patients before and during anaesthesia with paralysis and artificial ventilation. Inspired gas and pulmonary blood flow were measured with 133xenon and the chest was scanned with vertically moving counters at a lung volume of 1 litre above functional residual capacity. 2. Ventilation/unit lung volume was slightly greater and perfusion/unit lung volume substantially greater during anaesthesia in the dependent parts of the lungs. The spread of ventilation/perfusion ratios in supine conscious patients was small in comparison with that reported in upright conscious patients. During anaesthesia and artificial ventilation, the inequality of ventilation to perfusion was marginally increased in three of the four patients. 3. Ventilation/perfusion inequality alone was insufficient to explain the alveolar—arterial Po2 difference usually observed during anaesthesia.

Redistribution of pulmonary blood flow in the dog with PEEP ventilation

1979 ◽  
Vol 46 (2) ◽  
pp. 278-287 ◽  
Author(s):  
G. Hedenstierna ◽  
F. C. White ◽  
R. Mazzone ◽  
P. D. Wagner
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Pulmonary Blood Flow ◽  
Continuous Distribution ◽  
Isolated Lung ◽  
Flow Through ◽  
Peep Ventilation ◽  
Isolated Lungs ◽  
The Vertical Distribution ◽  
Ventilation And Perfusion

The effects of positive end-expiratory pressure (PEEP) at 20 cmH2O on the distribution of pulmonary blood flow was studied in intact dogs and isolated lung preparations. Measurements were made of a) the continuous distribution of ventilation-perfusion ratios (VA/Q), b) the vertical distribution of pulmonary blood flow, and c) the dimensions of the microvasculature. Without PEEP the distributions of ventilation and perfusion were unimodal and centered on a VA/Q close to one. Dependent regions received 5–10 times more of cardiac output than uppermost regions. With PEEP the distribution showed a bimodal character, one mode of normal VA/Q and the other comprising one-third of ventilation, lying between VA/Q of 10 and 100. Cardiac output was reduced two- to threefold and blood flow in the uppermost regions was grossly reduced but not eliminated. Bimodal distributions were also found in isolated lungs with PEEP, and histological examination of rapidly frozen lung tissue showed that alveolar capillaries were closed in the uppermost, poorly perfused regions, whereas alveolar corner vessels remained open. We suggest that the blood flow through these corner vessels is responsible for the additional, high VA/Q mode during PEEP.

Systemic and pulmonary vasomotor waves

1965 ◽  
Vol 209 (1) ◽  
pp. 37-50 ◽  
Author(s):  
Ricardo Ferretti ◽  
Neil S. Cherniack ◽  
Guy Longobardo ◽  
O. Robert Levine ◽  
Eugene Morkin ◽  
...  
Keyword(s):  
Blood Flow ◽  
Arterial Pressure ◽  
Pulmonary Blood Flow ◽  
Breathing Pattern ◽  
Pulmonary Arterial Pressure ◽  
Arterial Blood Flow ◽  
Mayer Waves ◽  
Arterial Blood ◽  
Vasomotor Activity ◽  
Pulmonary Arterial

Rhythmic oscillations in systemic arterial blood pressure (Mayer waves) were produced in the dog by metabolic acidosis; hypoxia generally augmented the amplitude of the Mayer waves. When the Mayer waves exceeded 20 mm Hg in amplitude, they were associated with rhythmic fluctuations in pulmonary arterial pressure. The pulmonary arterial waves resembled the Mayer waves with respect to frequency and independence of the breathing pattern but were generally smaller in amplitude Measurements of instantaneous pulmonary arterial blood flow indicate that the rhythmic fluctuations in pulmonary arterial pressure represent the passive effects of fluctuations in pulmonary blood flow rather than fluctuations in pulmonary vasomotor activity. In turn, the swings in pulmonary arterial blood flow appear to originate in rhythmic variations in systemic vasomotor activity.

Phosphorus eutrophication in the SW Frisian lake district 1. Monitoring and assessment of a dynamic mass balance model

Hydrobiologia ◽  
1992 ◽  
Vol 233 (1-3) ◽  
pp. 259-270 ◽  
Author(s):  
Harry J. W. J. Van Huet
Keyword(s):  
Mass Balance ◽  
Balance Model ◽  
Mass Balance Model ◽  
Lake District ◽  
Dynamic Mass

scholarly journals A Dynamic Mass-balance Model for Phosphorus in Lakes with a Focus on Criteria for Applicability and Boundary Conditions

2007 ◽  
Vol 187 (1-4) ◽  
pp. 119-147 ◽  
Author(s):  
Lars Håkanson ◽  
Andreas C. Bryhn
Keyword(s):  
Boundary Conditions ◽  
Mass Balance ◽  
Balance Model ◽  
Mass Balance Model ◽  
Dynamic Mass

Matching and mismatching ventilation and perfusion in the lung

1996 ◽  
Vol 16 (3) ◽  
pp. 23-27 ◽  
Author(s):  
RS Misasi ◽  
JL Keyes
Keyword(s):  
Blood Flow ◽  
Regional Differences ◽  
Pulmonary Blood Flow ◽  
Healthy Adults ◽  
Gas Composition ◽  
Blood Gas ◽  
Arterial Blood Gas ◽  
Arterial Blood ◽  
Different Types ◽  
Ventilation And Perfusion

Arterial blood-gas composition is determined by ventilation, pulmonary blood flow, and by how ventilation is matched to blood flow in the lungs. In healthy adults there are regional differences in both ventilation and blood flow in the lungs and the distribution of blood flow tends to parallel that of ventilation. Ventilation and blood flow can become mismatched in a variety of disease processes that affect the lungs. Mismatching of ventilation and perfusion causes decreased PaO2, may change PaCO2, and increases AaDO2 difference. Many different types of interventions are frequently necessary to treat mismatching of ventilation and perfusion.

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