Pulmonary blood flow distribution in panting ostriches

1982 ◽  
Vol 53 (6) ◽  
pp. 1411-1417 ◽  
Author(s):  
J. H. Jones
Keyword(s):  
Blood Flow ◽  
Heat Stress ◽  
Gas Exchange ◽  
Pulmonary Blood Flow ◽  
Flow Distribution ◽  
Respiratory Alkalosis ◽  
Blood Flow Distribution ◽  
Struthio Camelus ◽  
Severe Heat Stress ◽  
Dead Space Ventilation

Ostriches (Struthio camelus) are the only birds known that can increase post-dead space ventilation during severe heat stress without experiencing hypocapnia and respiratory alkalosis. To determine whether this phenomenon occurs due to redistribution of pulmonary blood flow during panting, thus creating an extreme ventilation-perfusion (V/Q) imbalance, the distributions of pulmonary blood flow in ostriches at rest (15 degrees C) and in severe panting (45 degrees C) were determined using radioactively labeled microspheres. Blood flow distribution at rest was greatest in the neopulmo [18% greater than mean pulmonary blood flow (MPBF)] and the cranial (23% greater than MPBF) and distal (12% greater than MPBF) regions of the paleopulmo. During panting blood flow was not shunted around the lung, and flow to the neopulmo decreased to MPBF, became more homogeneous along the craniocaudal axis, and remained nonhomogeneous along the mediolateral axis. The results suggest that the observed decrease in gas exchange during panting is probably due primarily to shunting of the increased ventilation around the parabronchial exchange region rather than to alterations in the patterns of V/Q within the lung.

Mechanisms of improvement in pulmonary gas exchange during isovolemic hemodilution

1999 ◽  
Vol 87 (1) ◽  
pp. 132-141 ◽  
Author(s):  
Steven Deem ◽  
Richard G. Hedges ◽  
Steven McKinney ◽  
Nayak L. Polissar ◽  
Michael K. Alberts ◽  
...  
Keyword(s):  
Blood Flow ◽  
Fractal Dimension ◽  
Gas Exchange ◽  
Spatial Correlation ◽  
Pulmonary Blood Flow ◽  
Minute Ventilation ◽  
Flow Distribution ◽  
Pulmonary Gas Exchange ◽  
Normal Lung ◽  
Blood Flow Distribution

Severe anemia is associated with remarkable stability of pulmonary gas exchange (S. Deem, M. K. Alberts, M. J. Bishop, A. Bidani, and E. R. Swenson. J. Appl. Physiol. 83: 240–246, 1997), although the factors that contribute to this stability have not been studied in detail. In the present study, 10 Flemish Giant rabbits were anesthetized, paralyzed, and mechanically ventilated at a fixed minute ventilation. Serial hemodilution was performed in five rabbits by simultaneous withdrawal of blood and infusion of an equal volume of 6% hetastarch; five rabbits were followed over a comparable time. Ventilation-perfusion (V˙a/Q˙) relationships were studied by using the multiple inert-gas-elimination technique, and pulmonary blood flow distribution was assessed by using fluorescent microspheres. Expired nitric oxide (NO) was measured by chemiluminescence. Hemodilution resulted in a linear fall in hematocrit over time, from 30 ± 1.6 to 11 ± 1%. Anemia was associated with an increase in arterial [Formula: see text] in comparison with controls ( P < 0.01 between groups). The improvement in O2 exchange was associated with reducedV˙a/Q˙heterogeneity, a reduction in the fractal dimension of pulmonary blood flow ( P = 0.04), and a relative increase in the spatial correlation of pulmonary blood flow ( P = 0.04). Expired NO increased with anemia, whereas it remained stable in control animals ( P < 0.0001 between groups). Anemia results in improved gas exchange in the normal lung as a result of an improvement in overallV˙a/Q˙matching. In turn, this may be a result of favorable changes in pulmonary blood flow distribution, as assessed by the fractal dimension and spatial correlation of blood flow and as a result of increased NO availability.

Hemodilution during Venous Gas Embolization Improves Gas Exchange, without Altering V̇A/Q̇ or Pulmonary Blood Flow Distributions 

1999 ◽  
Vol 91 (6) ◽  
pp. 1861-1861 ◽  
Author(s):  
Steven Deem ◽  
Steven McKinney ◽  
Nayak L. Polissar ◽  
Richard G. Hedges ◽  
Erik R. Swenson
Keyword(s):  
Blood Flow ◽  
Gas Exchange ◽  
Lung Injury ◽  
Partial Pressure ◽  
Pulmonary Blood Flow ◽  
Flow Distribution ◽  
Arterial Oxygen ◽  
Control Group ◽  
Blood Flow Distribution ◽  
Over Time

Background Isovolemic anemia results in improved gas exchange in rabbits with normal lungs but in relatively poorer gas exchange in rabbits with whole-lung atelectasis. In the current study, the authors characterized the effects of hemodilution on gas exchange in a distinct model of diffuse lung injury: venous gas embolization. Methods Twelve anesthetized rabbits were mechanically ventilated at a fixed rate and volume. Gas embolization was induced by continuous infusion of nitrogen via an internal jugular venous catheter. Serial hemodilution was performed in six rabbits by simultaneous withdrawal of blood and infusion of an equal volume of 6% hetastarch; six rabbits were followed as controls over time. Measurements included hemodynamic parameters and blood gases, ventilation-perfusion (V(A)/Q) distribution (multiple inert gas elimination technique), pulmonary blood flow distribution (fluorescent microspheres), and expired nitric oxide (NO; chemoluminescence). Results Venous gas embolization resulted in a decrease in partial pressure of arterial oxygen (PaO2) and an increase in partial pressure of arterial carbon dioxide (PaCO2), with markedly abnormal overall V(A)/Q distribution and a predominance of high V(A)/Q areas. Pulmonary blood flow distribution was markedly left-skewed, with low-flow areas predominating. Hematocrit decreased from 30+/-1% to 11+/-1% (mean +/- SE) with hemodilution. The alveolar-arterial PO2 (A-aPO2) difference decreased from 375+/-61 mmHg at 30% hematocrit to 218+/-12.8 mmHg at 15% hematocrit, but increased again (301+/-33 mmHg) at 11% hematocrit. In contrast, the A-aPO2 difference increased over time in the control group (P &lt; 0.05 between groups over time). Changes in PaO2 in both groups could be explained in large part by variations in intrapulmonary shunt and mixed venous oxygen saturation (SvO2); however, the improvement in gas exchange with hemodilution was not fully explained by significant changes in V(A)/Q or pulmonary blood flow distributions, as quantitated by the coefficient of variation (CV), fractal dimension, and spatial correlation of blood flow. Expired NO increased with with gas embolization but did not change significantly with time or hemodilution. Conclusions Isovolemic hemodilution results in improved oxygen exchange in rabbits with lung injury induced by gas embolization. The mechanism for this improvement is not clear.

Effect of Low Isoflurane Concentrations on the Ventilation–Perfusion Distribution in Injured Canine Lungs

2002 ◽  
Vol 97 (3) ◽  
pp. 652-659 ◽  
Author(s):  
Christian Putensen ◽  
Jukka Räsänen ◽  
Gabriele Putensen-Himmer ◽  
John B. Downs
Keyword(s):  
Blood Flow ◽  
Oleic Acid ◽  
Gas Exchange ◽  
Lung Injury ◽  
Oxygen Delivery ◽  
Pulmonary Blood Flow ◽  
Flow Distribution ◽  
Arterial Oxygen ◽  
Blood Flow Distribution ◽  
Low Concentrations

Background Rapid recovery and weaning from ventilatory support and cardiovascular stability are suggested advantages of isoflurane inhalation, in concentrations ranging from 0.1 to 0.6 vol%, for long-term sedation in mechanical ventilated patients. This study was designed to determine whether isoflurane in low concentrations impairs pulmonary gas exchange by increasing ventilation and perfusion (V(A)/Q) mismatch during lung injury. Methods Fourteen anesthetized dogs received in random order 0, 0.25, or 0.5 vol% end-tidal isoflurane before and after induction of lung injury with oleic acid. Gas exchange was assessed by blood gas analysis and by estimating the V(A)/Q distributions using the multiple inert gas elimination technique. Results Administration of oleic acid produced a lung injury with severe V(A)/Q mismatch and 38 +/- 4% intrapulmonary shunting of blood. During lung injury, isoflurane accounted for a dose-related increase in blood flow to shunt units from 38 +/- 4 to 42 +/- 3 (0.25 vol%) and 48 +/- 4% (0.5 vol%) (P &lt; 0.05), dispersion pulmonary blood flow distribution from 0.94 +/- 0.07 to 1.01 +/- 0.09 (0.25 vol%) and 1.11 +/- 0.11% (0.5 vol%) (P &lt; 0.05), and a decrease in perfusion of normal V(A)/Q units from 58 +/- 5 to 55 +/- 4 (0.25 vol%) and 50 +/- 4% (0.5 vol%) (P &lt; 0.05) (mean +/- SE). Isoflurane decreased arterial oxygen partial pressure from 72 +/- 4 to 62 +/- 4 mmHg (0.25 vol%) and 56 +/- 4 mmHg (0.5 vol%) (P &lt; 0.05) and oxygen delivery from 573 +/- 21 to 529 +/- 19 ml. kg. min (0.25 vol%) and 505 +/- 22 ml. kg. min (0.5 vol%) (P &lt; 0.05). Gas exchange, perfusion of shunt and normal V(A)/Q units, and pulmonary blood flow distribution was similar in absence of lung injury with and without isoflurane. Isoflurane 0.5 vol% lowered cardiac output during all conditions (P &lt; 0.05). CONCLUSIONS Inhalation of low concentrations of isoflurane contributed to increased V(A)/Q mismatch and decreased systemic blood flow and oxygen delivery in mechanically ventilated animals with injured lungs.

Pulmonary blood flow distribution after the total cavopulmonary connection for complex cardiac anomalies

1999 ◽  
Vol 14 (3) ◽  
pp. 154-160 ◽  
Author(s):  
Masao Tayama ◽  
Nobuaki Hirata ◽  
Tohru Matsushita ◽  
Tetsuya Sano ◽  
Norihide Fukushima ◽  
...  
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Flow Distribution ◽  
Total Cavopulmonary Connection ◽  
Blood Flow Distribution ◽  
Cardiac Anomalies ◽  
Cavopulmonary Connection

scholarly journals Pulmonary NO synthase inhibition and inspired CO2: effects on V ′/Q ′ and pulmonary blood flow distribution

2000 ◽  
Vol 16 (2) ◽  
pp. 288 ◽  
Author(s):  
T.V. Brogan ◽  
R.G. Hedges ◽  
S. McKinney ◽  
H.T. Robertson ◽  
M.P. Hlastala ◽  
...  
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Flow Distribution ◽  
No Synthase ◽  
Blood Flow Distribution ◽  
Co2 Effects

Pulmonary Blood Flow Distribution during Normal Ambulation

Respiration ◽  
1974 ◽  
Vol 31 (4) ◽  
pp. 289-295
Author(s):  
M. Arborelius, jr. ◽  
V. Lopéz-Majano ◽  
R.C. Reba ◽  
T.K. Natarajan
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Flow Distribution ◽  
Blood Flow Distribution

scholarly journals Headed in the Wrong Direction: Chronic and Acute Derangements in Pulmonary Blood Flow Distribution in a Patient with Severe Pulmonary Vein Stenosis

2019 ◽  
Vol 16 (10) ◽  
pp. 1321-1326 ◽  
Author(s):  
Luisa Morales-Nebreda ◽  
Christopher S. Chung ◽  
Rishi Agrawal ◽  
Anjana V. Yeldandi ◽  
Benjamin D. Singer ◽  
...  
Keyword(s):  
Blood Flow ◽  
Pulmonary Vein ◽  
Pulmonary Blood Flow ◽  
Flow Distribution ◽  
Pulmonary Vein Stenosis ◽  
Blood Flow Distribution ◽  
Wrong Direction ◽  
Vein Stenosis

Pulmonary blood flow distribution in standing horses is not dominated by gravity

1996 ◽  
Vol 81 (3) ◽  
pp. 1051-1061 ◽  
Author(s):  
M. P. Hlastala ◽  
S. L. Bernard ◽  
H. H. Erickson ◽  
M. R. Fedde ◽  
E. M. Gaughan ◽  
...  
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Flow Distribution ◽  
Correlation Coefficients ◽  
Vertical Gradient ◽  
Standing Position ◽  
Central Vein ◽  
Least Squares Regression ◽  
Blood Flow Distribution ◽  
Considerable Heterogeneity

Recent studies using microspheres in dogs, pigs and goats have demonstrated considerable heterogeneity of pulmonary perfusion within isogravitational planes. These studies demonstrate a minimal role of gravity in determining pulmonary blood flow distribution. To test whether a gravitational gradient would be more apparent in an animal with large vertical lung height, we measured perfusion heterogeneity in horses (vertical lung height = approximately 55 cm). Four unanesthetized Thoroughbred geldings (422-500 kg) were studied awake in the standing position with fluorescent microspheres injected into a central vein. Between 1,621 and 2,503 pieces (1.3 cm3 in volume) were obtained from the lungs of each horse with spatial coordinates, and blood flow was determined for each piece. The coefficient of variation of blood flow throughout the lungs ranged between 22 and 57% among the horses. Considerable heterogeneity was seen in each isogravitational plane. The relationship between blood flow and vertical height up the lung was characterized by the slope and correlation coefficient of a least squares regression analysis. The slopes within each horse ranged from -0.052 to +0.021 relative flow units/cm height up the lung, and the correlation coefficients varied from 0.12 to 0.75. A positive slope, indicating that flow increased with vertical distance up the lung (opposite to gravity), was observed in three of the four horses. In addition, blood flow was uniformly low in three of the four horses in the most cranial portions of the lungs. We conclude that in lungs of resting unanesthetized horses, animals with a large lung height, there is no consistent vertical gradient to pulmonary blood flow and there is a considerable degree of perfusion heterogeneity, indicating that gravity alone does not play the major role in determining blood flow distribution.

Role of Rho-kinase signaling and endothelial dysfunction in modulating blood flow distribution in pulmonary hypertension

2011 ◽  
Vol 110 (4) ◽  
pp. 901-908 ◽  
Author(s):  
Daryl O. Schwenke ◽  
James T. Pearson ◽  
Takashi Sonobe ◽  
Hatsue Ishibashi-Ueda ◽  
Akito Shimouchi ◽  
...  
Keyword(s):  
Blood Flow ◽  
Endothelial Dysfunction ◽  
Pulmonary Blood Flow ◽  
Left Lung ◽  
Rho Kinase ◽  
Flow Distribution ◽  
Fundamental Result ◽  
Internal Diameter ◽  
Blood Flow Distribution ◽  
Male Adult

Rho-kinase-mediated vasoconstriction and endothelial dysfunction are considered two primary instigators of pulmonary arterial hypertension (PAH). However, their contribution to the adverse changes in pulmonary blood flow distribution associated with PAH has not been addressed. This study utilizes synchrotron radiation microangiography to assess the specific role, and contribution of, Rho-kinase-mediated vasoconstriction and endothelial dysfunction in PAH. Male adult Sprague-Dawley rats were injected with saline (Cont-rats) or monocrotaline (MCT-rats) 3 wk before microangiography was performed on the left lung. We assessed dynamic changes in vessel internal diameter (ID) in response to 1) the Rho-kinase inhibitor fasudil (10 mg/kg iv); or 2) ACh (3 μg · kg−1 · min−1), sodium nitroprusside (SNP, 5 μg · kg−1 · min−1), and Nω-nitro-l-arginine methyl ester (l-NAME, 50 mg/kg iv). We observed that MCT-rats had fewer vessels of the microcirculation compared with Cont-rats. The fundamental result of this study is that fasudil improved pulmonary blood flow distribution and reduced pulmonary pressure in PAH rats, not only by dilating already-perfused vessels (ID > 100 μm), but also by restoring blood flow to vessels that had previously been constricted closed (ID < 100 μm). Endothelium-dependent vasodilation was impaired in MCT-rats primarily in vessels with an ID < 200 μm. Moreover the vasoconstrictor response to l-NAME was accentuated in MCT-rats, but only in the 200- to 300-μm vessels. These results highlight the importance of Rho-kinase-mediated control and endothelial control of pulmonary vascular tone in PAH. Indeed, an effective therapeutic strategy for treating PAH should target both the smooth muscle Rho-kinase and endothelial pathways.

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