Spatial distribution of ventilation and perfusion in anesthetized dogs in lateral postures

2002 ◽  
Vol 92 (2) ◽  
pp. 745-762 ◽  
Author(s):  
Hung Chang ◽  
Stephen J. Lai-Fook ◽  
Karen B. Domino ◽  
Carmel Schimmel ◽  
Jack Hildebrandt ◽  
...  
Keyword(s):  
Blood Flow ◽  
Gas Exchange ◽  
Regional Blood Flow ◽  
Linear Regression Analysis ◽  
Regional Distribution ◽  
Left Lung ◽  
Vertical Gradient ◽  
Fluorescent Microspheres ◽  
Lateral Decubitus ◽  
Ventilation And Perfusion

We aimed to assess the influence of lateral decubitus postures and positive end-expiratory pressure (PEEP) on the regional distribution of ventilation and perfusion. We measured regional ventilation (V˙a) and regional blood flow (Q˙) in six anesthetized, mechanically ventilated dogs in the left (LLD) and right lateral decubitus (RLD) postures with and without 10 cmH2O PEEP. Q˙ was measured by use of intravenously injected 15-μm fluorescent microspheres, and V˙a was measured by aerosolized 1-μm fluorescent microspheres. Fluorescence was analyzed in lung pieces ∼1.7 cm3 in volume. Multiple linear regression analysis was used to evaluate three-dimensional spatial gradients ofQ˙, V˙a, the ratio V˙a/Q˙, and regional Po 2 (PrO2 ) in both lungs. In the LLD posture, a gravity-dependent vertical gradient in Q˙ was observed in both lungs in conjunction with a reduced blood flow and PrO2 to the dependent left lung. Change from the LLD to the RLD or 10 cmH2O PEEP increased localV˙a/Q˙ and PrO2 in the left lung and minimized any role of hypoxia. The greatest reduction in individual lung volume occurred to the left lung in the LLD posture. We conclude that lung distortion caused by the weight of the heart and abdomen is greater in the LLD posture and influences both Q˙ andV˙a, and ultimately gas exchange. In this respect, the smaller left lung was the most susceptible to impaired gas exchange in the LLD posture.

The Unpredictable Effect of Changing Cardiac Output on Hypoxemia after Acute Pulmonary Thromboembolism

2008 ◽  
Vol 2 ◽  
pp. CCRPM.S773
Author(s):  
John Y. C. Tsang ◽  
Wayne J. E. Lamm ◽  
Blazej Neradilek ◽  
Nayak L. Polissar ◽  
Michael P. Hlastala
Keyword(s):  
Cluster Analysis ◽  
Blood Flow ◽  
Cardiac Output ◽  
Gas Exchange ◽  
Clinical Setting ◽  
Pulmonary Thromboembolism ◽  
Regional Blood Flow ◽  
The Other ◽  
Fluorescent Microspheres ◽  
Acute Pulmonary Thromboembolism

Previous studies reported that the degree of hypoxemia following acute pulmonary thromboembolism (APTE) was highly variable and that its mechanism was mainly due to the creation of many high and low ventilation/perfusion (V/Q) units, as a result of the heterogeneous regional blood flow (Q) caused by embolic obstruction. We studied the effect of changing cardiac output (Qt) on gas exchange after APTE in 5 embolized piglets (23 ± 3 Kg), using Dobutamine intermittently at approximately 20 μg/kg/min for 120 minutes. The distribution of ventilation (V) and perfusion (Q) at various times was mapped using fluorescent microspheres in 941 ± 60 lung regions. After APTE, increase in Qt by Dobutamine improved venous oxygen tension (PvO2) but arterial PaO2 did not change consistently. On the other hand, cluster analysis showed that the V/Q ratio of most lung regions was lowered due to increases in Q at the same time. We concluded that the effect of changing cardiac output on gas exchange following APTE was affected by the simultaneous and varying balance between the changing V/Q mismatch and the concomitantly changing PvO2, which might explain the unpredictability of PaO2 in the clinical setting.

Pulmonary embolization causes hypoxemia by redistributing regional blood flow without changing ventilation

1998 ◽  
Vol 85 (6) ◽  
pp. 2337-2343 ◽  
Author(s):  
William A. Altemeier ◽  
H. Thomas Robertson ◽  
Steve McKinney ◽  
Robb W. Glenny
Keyword(s):  
Blood Flow ◽  
Regional Blood Flow ◽  
Alveolar Ventilation ◽  
Regional Perfusion ◽  
Regional Ventilation ◽  
Fluorescent Microspheres ◽  
Mechanically Ventilated ◽  
Before And After ◽  
Pulmonary Embolization ◽  
Ventilation And Perfusion

To explore mechanisms of hypoxemia after acute pulmonary embolism, we measured regional pulmonary blood flow and alveolar ventilation before and after embolization with 780-μm beads in five anesthetized, mechanically ventilated pigs. Regional ventilation and perfusion were determined in ∼2.0-cm3 lung volumes by using 1-μm-diameter aerosolized and 15-μm-diameter injected fluorescent microspheres. Hypoxemia after embolization resulted from increased perfusion to regions with low ventilation-to-perfusion ratios. Embolization caused an increase in perfusion heterogeneity and a fall in the correlation between ventilation and perfusion. Correlation between regional ventilation pre- and postembolization was greater than correlation between regional perfusion pre- and postembolization. The majority of regional ventilation-to-perfusion ratio heterogeneity was attributable to changes in regional perfusion. Regional perfusion redistribution without compensatory changes in regional ventilation is responsible for hypoxemia after pulmonary vascular embolization in pigs.

Effect of posture on regional gas exchange in pigs

2004 ◽  
Vol 97 (6) ◽  
pp. 2104-2111 ◽  
Author(s):  
William A. Altemeier ◽  
Steve McKinney ◽  
Melissa Krueger ◽  
Robb W. Glenny
Keyword(s):  
Blood Flow ◽  
Gas Exchange ◽  
Oxygen Tension ◽  
Regional Blood Flow ◽  
Flow Distribution ◽  
Regional Ventilation ◽  
Total Blood ◽  
Ventilation Heterogeneity ◽  
Alveolar Oxygen ◽  
Ventilation And Perfusion

Although recent high-resolution studies demonstrate the importance of nongravitational determinants for both pulmonary blood flow and ventilation distributions, posture has a clear impact on whole lung gas exchange. Deterioration in arterial oxygenation with repositioning from prone to supine posture is caused by increased heterogeneity in the distribution of ventilation-to-perfusion ratios. This can result from increased heterogeneity in regional blood flow distribution, increased heterogeneity in regional ventilation distribution, decreased correlation between regional blood flow and ventilation, or some combination of the above (Wilson TA and Beck KC, J Appl Physiol 72: 2298–2304, 1992). We hypothesize that, although repositioning from prone to supine has relatively small effects on overall blood flow and ventilation distributions, regional changes are poorly correlated, resulting in regional ventilation-perfusion mismatch and reduction in alveolar oxygen tension. We report ventilation and perfusion distributions in seven anesthetized, mechanically ventilated pigs measured with aerosolized and injected microspheres. Total contributions of pulmonary structure and posture on ventilation and perfusion heterogeneities were quantified by using analysis of variance. Regional gradients of posture-mediated change in ventilation, perfusion, and calculated alveolar oxygen tension were examined in the caudocranial and ventrodorsal directions. We found that pulmonary structure was responsible for 74.0 ± 4.7% of total ventilation heterogeneity and 63.3 ± 4.2% of total blood flow heterogeneity. Posture-mediated redistribution was primarily oriented along the caudocranial axis for ventilation and along the ventrodorsal axis for blood flow. These mismatched changes reduced alveolar oxygen tension primarily in the dorsocaudal lung region.

Regional distribution of blood flow in awake heat-stressed baboons

1979 ◽  
Vol 237 (6) ◽  
pp. H705-H712 ◽  
Author(s):  
J. R. Hales ◽  
L. B. Rowell ◽  
R. B. King
Keyword(s):  
Blood Flow ◽  
Heat Stress ◽  
Regional Blood Flow ◽  
Regional Distribution ◽  
Renal Vasoconstriction ◽  
Suitable Animal Model ◽  
Mean Pressure ◽  
Subcutaneous Adipose ◽  
Arterial Po2 ◽  
The Brain

Radioactive microspheres (containing six different nuclide labels) were used to measure blood flow (BF) to most major organs of eight conscious baboons during heat stress. Cardiac output (CO), arterial mean pressure, and arterial PO2, PCO2, and pH did not change, but heart rate increased and stroke volume fell as body temperature increased by as much as 2.56 degrees C. Skin BF increased in all regions sampled so that the fraction of CO distributed to skin (not including feet and hands) increased from 3% (control) to 14%. Increased skin BF was compensated for by decreases in splanchnic (intestines, stomach, pancreas, and spleen) (35%), renal (27%), and possibly muscle BF. There was no change in BF to the brain, spinal cord, coronary, or subcutaneous adipose tissue during heating. Therefore, baboons show a generalized redistribution of BF during heat stress, so that increments in skin BF are provided without increases in CO, whereas man depends on changes in both; despite this latter difference between the baboon and man, the similarity in magnitude of the splanchnic and renal vasoconstriction between the two primates may indicate that the baboon would be a suitable animal model for investigations into mechanisms of changes in regional blood flow in man during heat stress.

Unilateral lung edema: effects on pulmonary gas exchange, hemodynamics, and pulmonary perfusion distribution

2000 ◽  
Vol 89 (4) ◽  
pp. 1513-1521 ◽  
Author(s):  
Klaus Slama ◽  
Mareike Gesch ◽  
Johannes C. Böck ◽  
Sylvia M. Pietschmann ◽  
Walter Schaffartzik ◽  
...  
Keyword(s):  
Blood Flow ◽  
Gas Exchange ◽  
Pulmonary Artery ◽  
Venous Pressure ◽  
Pulmonary Gas Exchange ◽  
The Other ◽  
Lung Edema ◽  
Pulmonary Perfusion ◽  
Central Venous ◽  
Fluorescent Microspheres

Two types of unilateral lung edema in sheep were characterized regarding their effects on pulmonary gas exchange, hemodynamics, and distribution of pulmonary perfusion. One edema type was induced with aerosolized HCl (0.15 M, pH 1.0) and the other with NaCl (0.15 M, pH 7.4). Both aerosols were nebulized continuously for 4 h into left lungs. In HCl-treated animals, pulmonary gas exchange deteriorated [from a partial arterial O2 pressure-to-inspired O2 fraction ratio (PaO2 /Fi O2 ) of 254 at baseline to 187 after 4 h HCl]. In addition, pulmonary artery pressure and total pulmonary vascular resistance increased (from 16 to 19 mmHg and from 133 to 154 dyn · s · cm−5, respectively). In NaCl-treated animals, only the central venous pressure significantly increased (from 7 to 9 mmHg). Distribution of pulmonary perfusion (measured with fluorescent microspheres) changed differently in both groups. After HCl application, 6% more blood flow was directed to the treated lung, whereas, after NaCl, 5% more blood flow was directed to the untreated lung. HCl and NaCl treatment both induce an equivalent lung edema, but only HCl treatment is associated with gas exchange alteration and tissue damage. Redistribution of pulmonary perfusion maintains gas exchange during NaCl treatment and decreases it during HCl inhalation.

Ventilation-perfusion relationship in young healthy awake and anesthetized-paralyzed man

1979 ◽  
Vol 47 (4) ◽  
pp. 745-753 ◽  
Author(s):  
K. Rehder ◽  
T. J. Knopp ◽  
A. D. Sessler ◽  
E. P. Didier
Keyword(s):  
Blood Flow ◽  
Healthy Volunteers ◽  
Dead Space ◽  
Flow Distribution ◽  
Blood Flow Distribution ◽  
Alveolar Dead Space ◽  
Awake State ◽  
Lateral Decubitus ◽  
Inspired Oxygen ◽  
Ventilation And Perfusion

Distributions of ventilation and perfusion relative to Va/Q were determined in seven young healthy volunteers (24–33 yr) while they were either in the supine or right lateral decubitus position. The subjects were studied first awake and then while anesthetized-paralyzed and breathing 30% oxygen and again while breathing 100% oxygen. In the awake state, no statistically significant differences were observed in the distribution of ventilation and perfusion relative to Va/Q between the supine and right lateral decubitus positions or on changing the inspired oxygen concentrations. After induction of anesthesia-paralysis, Va/Q mismatching increased significantly but only small right-to-left intrapulmonary shunts developed. Ventilating the lungs with 100% oxygen further increased the dispersion of blood flow distribution during anesthesia-paralysis; lung units with low Va/Q or right-to-left intrapulmonary shunts (or both) developed. With induction of anesthesia-paralysis and intubation of the trachea, the anatomic dead space was decreased and the alveolar dead space increased.

Cardiovascular adjustments to laboratory diving in beavers and nutria

1982 ◽  
Vol 242 (5) ◽  
pp. R434-R440
Author(s):  
T. McKean
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Regional Blood Flow ◽  
Castor Canadensis ◽  
Venous Blood ◽  
Regional Distribution ◽  
Blood Gases ◽  
Myocastor Coypus ◽  
Recovery From Anesthesia ◽  
Rate Of Decline

Beavers (Castor canadensis) and nutria (Myocastor coypus) were anesthetized with halothane and catheters placed in the left ventricle, aorta and pulmonary artery, right ventricle or right atrium. The animals were strapped to a board and following recovery from anesthesia the following measurements were taken: regional distribution of blood flow, cardiac output, O2 consumption, arterial and venous blood gases, and pH. The animal was then immersed in 15-20 degrees C water for up to 2.75 min (nutria) or 4 min (beaver) and the measurements repeated. Heart rate and cardiac output decreased by 80 and 75%, respectively. Arterial and venous oxygen partial pressure and content fell as did pH whereas CO2 pressures rose during diving. Oxygen consumption at rest was 124 and 102% of that predicted on the basis of body mass for the beaver and nutria, respectively. Rate of decline of O2 stores during diving decreased by 93% in beavers and 89% in nutria compared to the predive value. Regional blood flow decreased to all organs except the adrenals, heart, and lungs. Blood flow to the brain increased during diving.

Estimated regional blood flow by rubidium 86 distribution during arousal from hibernation

1962 ◽  
Vol 203 (2) ◽  
pp. 266-270 ◽  
Author(s):  
Robert W. Bullard ◽  
Gordon E. Funkhouser
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Ground Squirrel ◽  
Regional Blood Flow ◽  
Regional Distribution ◽  
Arousal Level ◽  
Blood Flows

The local organ or tissue blood flows during the process of arousal from hibernation have been estimated in the 13-lined ground squirrel by the Sapirstein method, which consists of the measurement of the regional distribution of injected rubidium 86. The studies demonstrated that during arousal there is a confinement of blood flow to the thoracic regions. After the heart rate has attained 100 beats/min, blood flow increases to the anterior portions of the animal. At the arousal level characterized by a heart rate of 200 beats/min, blood flow to anterior and thoracic tissue had attained levels almost equal to control flows. Posterior tissue flows were still much lower than control flows. The centralization of blood flow to thoracic and anterior tissues did not occur in the rat in the hypothermic state.

Regional distribution of blood flow of dogs during graded dynamic exercise

1987 ◽  
Vol 63 (6) ◽  
pp. 2269-2277 ◽  
Author(s):  
T. I. Musch ◽  
D. B. Friedman ◽  
K. H. Pitetti ◽  
G. C. Haidet ◽  
J. Stray-Gundersen ◽  
...  
Keyword(s):  
Blood Flow ◽  
Maximal Exercise ◽  
Regional Blood Flow ◽  
Regional Distribution ◽  
Work Load ◽  
Work Intensity ◽  
Semitendinosus Muscle ◽  
Blood Flows ◽  
Flow Response ◽  
Semimembranosus Muscle

The regional blood flow response to progressive treadmill exercise was measured with radioactive microspheres in 25 untrained mongrel dogs. Incremental increases in work intensity resulted in corresponding increases in blood flows to the gracilis, gastrocnemius, semimembranosus, and semitendinosus muscles of the hindlimb and to the heart. During maximal exercise, blood flow was greatest in the semimembranosus muscle and lowest in the semitendinosus muscle (342 and 134 ml–1.100 g tissue-1.min-1, respectively). Exercise produced a decrease in blood flow to the temporalis muscle, which was classified as nonlocomotive in function. Blood flows to the stomach, pancreas, and large intestine decreased at the lowest exercise work load and remained diminished throughout the continuum to maximal exercise. Blood flows to the small intestine and spleen were maintained during submaximal exercise but were reduced by 50% at maximal O2 consumption (VO2max). No changes in blood flows to the kidneys, adrenal glands, liver, and brain were found. These results demonstrate that 1) renal blood flow is maintained at resting levels during exercise in untrained dogs; 2) blood flow changes in the various organs of the splanchnic region of dogs during exercise are heterogeneous; and 3) blood flows to the working skeletal muscles of dogs progressively increase with increasing work loads up to VO2max.

scholarly journals Effect of Astrocytic Energy Metabolism Depressant on 14C-Acetate Uptake in Intact Rat Brain

2004 ◽  
Vol 24 (2) ◽  
pp. 188-190 ◽  
Author(s):  
Rie Hosoi ◽  
Maki Okada ◽  
Jun Hatazawa ◽  
Antony Gee ◽  
Osamu Inoue
Keyword(s):  
Blood Flow ◽  
Energy Metabolism ◽  
Rat Brain ◽  
Regional Blood Flow ◽  
Regional Distribution ◽  
Acetate Uptake ◽  
Minute Period ◽  
Intact Brain ◽  
The Right

Fluorocitrate, a selective astrocytic toxin, was microinjected into the right striatum of rat brain, and the regional distribution of 14C-acetate was measured using autoradiography. A significant reduction (more than 80%) in 14C-acetate uptake over a 5-minute period was observed in the right striatum, compared with that in the left striatum (saline infused), 4 hours after fluorocitrate (1 nmol/μL) infusion. This effect was transient, and 14C-acetate uptake had almost returned to normal at 24 hours after the fluorocitrate infusion. In contrast, the regional blood flow in the striatum, as determined using 14C-iodoamphetamine, was significantly increased by the fluorocitrate infusion. The present observations indicate that 14C-acetate uptake might be a useful characteristic for examining astrocytic energy metabolism in the intact brain.

Sign in / Sign up

Export Citation Format

Share Document