The response of the pulmonary circulation to exercise during normoxia and hypoxia following pneumonectomy in the adult sheep

1989 ◽  
Vol 67 (3) ◽  
pp. 202-206 ◽  
Author(s):  
Michele Smith ◽  
Geoffrey Coates ◽  
J. Michael Kay ◽  
Hugh O'Brodovich
Keyword(s):  
Blood Flow ◽  
Arterial Pressure ◽  
Pulmonary Arterial Pressure ◽  
Hemodynamic Response ◽  
Pulmonary Hemodynamics ◽  
Vascular Reserve ◽  
Mean Pulmonary Arterial Pressure ◽  
Pulmonary Hemodynamic ◽  
Pulmonary Arterial ◽  
Increased Blood Flow

Pneumonectomy approximately halves the available pulmonary vascular bed. It is unknown whether the remaining lung has sufficient vascular reserve to cope with increased blood flow under stressful conditions without demonstrating abnormal pulmonary hemodynamics. To investigate this question, unanesthetized ewes with vascular catheters had hemodynamics assessed before and after a left pneumonectomy. Subsequently, on different days, the sheep were exercised on a treadmill under normoxic and hypobaric hypoxic (430 mmHg) (1 mmHg = 133.3 Pa) conditions. Pneumonectomy itself increased mean pulmonary arterial pressure by 4 mmHg. During normoxic or hypoxic exercise, the pneumonectomized sheep demonstrated a pulmonary hemodynamic response similar to normal sheep with two lungs. The pressure–flow relation for the right lung suggested the vascular reserve of the lung was not exceeded during exercise in the pneumonectomized sheep. Eighteen to 70 days after pneumonectomy there was no evidence of right ventricular hypertrophy, but there were small increases in the number of muscularized vessels less than 50 μm diameter and in the amount of muscle in normally muscularized pulmonary arteries. This study demonstrates that pneumonectomy slightly increases mean pulmonary arterial pressure. However, there is sufficient vascular reserve in the remaining lung to permit a normal hemodynamic response to exercise-induced increased blood flow even under hypoxic conditions.Key words: pulmonary hypertension, pneumonectomy, sheep.

Pulmonary hemodynamics at birth: effect of acute cyclooxygenase inhibition in lambs

1988 ◽  
Vol 64 (4) ◽  
pp. 1676-1682 ◽  
Author(s):  
D. Davidson
Keyword(s):  
Arterial Pressure ◽  
Pulmonary Arterial Pressure ◽  
Indicator Dilution ◽  
Spontaneous Respiration ◽  
Group Differences ◽  
Saline Control ◽  
Pulmonary Hemodynamics ◽  
Mean Pulmonary Arterial Pressure ◽  
Pulmonary Arterial ◽  
Arterial Po2

The effect of acute cyclooxygenase (CYO) inhibition on the cardiopulmonary adjustments at birth was examined in chronically instrumented, unanesthetized, term lambs before, during, and after cesarean section (spontaneous respiration). One of three infusions was started 20 min before birth: saline control (C, n = 6), indomethacin (I, n = 6), or meclofenamate (M, n = 3). The stable metabolite of prostacyclin, plasma 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha, aorta), was measured by radioimmunoassay as an index of CYO activity. Indomethacin blocked the rise of 6-keto-PGF1 alpha observed in control lambs after birth and indomethacin-treated lambs exhibited an attenuation of the postnatal decrease in mean pulmonary arterial pressure. Pulmonary arterial pressure (Ppa) was 53 +/- 2 and 47 +/- 2 Torr (mean +/- SE) at 15 min and 40 +/- 3 and 34 +/- 2 Torr at 120 min in I and C groups, respectively. There were no serial or group differences in cardiac output and cardiac right to left shunt (indicator dilution) from 15 to 120 min after birth. Arterial PO2 (PaO2) was not different between groups: 37 +/- 4 Torr at 15 min and 47 +/- 5 min at 120 min after birth (control lambs). The results for I and M were similar for all measurements.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulmonary hemodynamic reaction to foreign blood in goats and rabbits

1991 ◽  
Vol 71 (6) ◽  
pp. 2231-2237 ◽  
Author(s):  
K. Enzan ◽  
Y. Wang ◽  
E. Schultz ◽  
F. Stravros ◽  
M. D. Mitchell ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Pulmonary Arterial Pressure ◽  
Thromboxane B2 ◽  
Pulmonary Hemodynamics ◽  
Pulmonary Hemodynamic ◽  
Pulmonary Capillaries ◽  
Lower Reactivity ◽  
Pulmonary Arterial ◽  
Maximal Rise ◽  
Dose Dependent

We have found that the goat is extraordinarily sensitive to very small quantities of rabbit or rat blood. As little as 0.004 ml/kg induces transient pulmonary hypertension [maximal rise in pulmonary arterial pressure 32 +/- 10 (SD) cmH2O] in goats. We hypothesized that this reaction may be related to the presence of the resident population of intravascular macrophages that reside in the pulmonary capillaries of goats. If that is so, then rabbits or rats, which have few or no intravascular macrophages, should not be reactive to foreign blood. We compared pulmonary hemodynamics and changes in blood thromboxane B2 concentrations among goats, rabbits, and rats in response to graded doses of foreign blood. The pulmonary reaction to foreign blood was much greater in goats than in rabbits or rats, even though we injected up to 10- or 60-fold larger amounts into the latter species. In goats the pulmonary vascular pressure response to rabbit blood was dose dependent in goats and correlated well with changes in systemic arterial thromboxane B2 concentrations [change in pulmonary arterial pressure = 0.07 (thromboxane B2) + 8.3, r = 0.79]. We also tested the prostaglandin H2 endoperoxide analogue (U-46619) and found that the goats are somewhat more reactive than rabbits. We conclude that the pulmonary hemodynamic reaction to foreign blood is consistent with the concept that the foreign erythrocytes are reacting with the pulmonary intravascular macrophages in goats. The lower reactivity of the rabbit pulmonary circulation to thromboxane may also have a role.

Pulmonary hemodynamics in fetal lambs during development at normal and increased oxygen tension

1992 ◽  
Vol 73 (1) ◽  
pp. 213-218 ◽  
Author(s):  
F. C. Morin ◽  
E. A. Egan
Keyword(s):  
Blood Flow ◽  
Arterial Pressure ◽  
Oxygen Tension ◽  
Pulmonary Blood Flow ◽  
Pulmonary Arterial Pressure ◽  
Vessel Density ◽  
Pulmonary Resistance ◽  
Pulmonary Hemodynamics ◽  
Fetal Sheep ◽  
Pulmonary Arterial

During the latter third of gestation, the number of resistance vessels in the lungs of the fetal sheep increases by 10-fold even after correction for lung growth. We measured pulmonary arterial pressure and blood flow directly and calculated total pulmonary resistance (pressure divided by flow) in intrauterine fetal lambs at 93–95 days and at 136 days of gestation (term is 145–148 days). In addition, we used a hyperbaric chamber to increase oxygen tension in the fetuses and measured the effect on the pulmonary circulation. When corrected for wet weight of the lungs, pulmonary blood flow did not change with advancing gestation (139 +/- 42 to 103 +/- 45 ml.100 g-1.min-1). Pulmonary arterial pressure increased (42 +/- 5 to 49 +/- 3 mmHg); thus total pulmonary resistance increased with advancing gestation from 0.32 +/- 0.12 to 0.55 +/- 0.21 mmHg.100 g.min.ml-1. If the blood flow is corrected for dry weight of the lungs, neither pulmonary blood flow nor total pulmonary resistance changed with advancing gestation. Increasing oxygen tension increased pulmonary blood flow 10-fold in the more mature fetuses but only 0.2-fold in the less mature fetuses. At the normal low oxygen tension of the fetus, pulmonary blood flow does not increase between these two points of gestation in the fetal lamb despite the increase in vessel density in the lungs. However, during elevated oxygen tension, pulmonary blood flow does increase in proportion to the increase in vessel density.

Regional pulmonary blood flow during 96 hours of hypoxia in conscious sheep

1986 ◽  
Vol 61 (6) ◽  
pp. 2136-2143 ◽  
Author(s):  
D. C. Curran-Everett ◽  
K. McAndrews ◽  
J. A. Krasney
Keyword(s):  
Blood Flow ◽  
Arterial Pressure ◽  
Pulmonary Blood Flow ◽  
Pulmonary Arterial Pressure ◽  
Pressor Response ◽  
Superior Vena ◽  
Acute Hypoxia ◽  
Vena Cava ◽  
Normobaric Hypoxia ◽  
Pulmonary Arterial

The effects of acute hypoxia on regional pulmonary perfusion have been studied previously in anesthetized, artificially ventilated sheep (J. Appl. Physiol. 56: 338–342, 1984). That study indicated that a rise in pulmonary arterial pressure was associated with a shift of pulmonary blood flow toward dorsal (nondependent) areas of the lung. This study examined the relationship between the pulmonary arterial pressor response and regional pulmonary blood flow in five conscious, standing ewes during 96 h of normobaric hypoxia. The sheep were made hypoxic by N2 dilution in an environmental chamber [arterial O2 tension (PaO2) = 37–42 Torr, arterial CO2 tension (PaCO2) = 25–30 Torr]. Regional pulmonary blood flow was calculated by injecting 15-micron radiolabeled microspheres into the superior vena cava during normoxia and at 24-h intervals of hypoxia. Pulmonary arterial pressure increased from 12 Torr during normoxia to 19–22 Torr throughout hypoxia (alpha less than 0.049). Pulmonary blood flow, expressed as %QCO or ml X min-1 X g-1, did not shift among dorsal and ventral regions during hypoxia (alpha greater than 0.25); nor were there interlobar shifts of blood flow (alpha greater than 0.10). These data suggest that conscious, standing sheep do not demonstrate a shift in pulmonary blood flow during 96 h of normobaric hypoxia even though pulmonary arterial pressure rises 7–10 Torr. We question whether global hypoxic pulmonary vasoconstriction is, by itself, beneficial to the sheep.

A computed method for noninvasive MRI assessment of pulmonary arterial hypertension

2004 ◽  
Vol 96 (2) ◽  
pp. 463-468 ◽  
Author(s):  
Eric Laffon ◽  
Christophe Vallet ◽  
Virginie Bernard ◽  
Michel Montaudon ◽  
Dominique Ducassou ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Pulmonary Arterial Pressure ◽  
Cross Sectional Area ◽  
Physical Parameters ◽  
Sectional Area ◽  
Biophysical Parameters ◽  
Cross Sectional ◽  
Mean Pulmonary Arterial Pressure ◽  
Pulmonary Arterial ◽  
The Mean

The present method enables the noninvasive assessment of mean pulmonary arterial pressure from magnetic resonance phase mapping by computing both physical and biophysical parameters. The physical parameters include the mean blood flow velocity over the cross-sectional area of the main pulmonary artery (MPA) at the systolic peak and the maximal systolic MPA cross-sectional area value, whereas the biophysical parameters are related to each patient, such as height, weight, and heart rate. These parameters have been measured in a series of 31 patients undergoing right-side heart catheterization, and the computed mean pulmonary arterial pressure value (PpaComp) has been compared with the mean pressure value obtained from catheterization (PpaCat) in each patient. A significant correlation was found that did not differ from the identity line PpaComp = PpaCat ( r = 0.92). The mean and maximal absolute differences between PpaComp and PpaCat were 5.4 and 11.9 mmHg, respectively. The method was also applied to compute the MPA systolic and diastolic pressures in the same patient series. We conclude that this computed method, which combines physical (whoever the patient) and biophysical parameters (related to each patient), improves the accuracy of MRI to noninvasively estimate pulmonary arterial pressures.

scholarly journals Mean pulmonary arterial pressure after percutaneous mitral valvuloplasty predicts long-term adverse outcomes

2012 ◽  
Vol 31 (1) ◽  
pp. 19-25 ◽  
Author(s):  
Elisabete Jorge ◽  
Rui Baptista ◽  
Henrique Faria ◽  
João Calisto ◽  
Vítor Matos ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Pulmonary Arterial Pressure ◽  
Adverse Outcomes ◽  
Mitral Valvuloplasty ◽  
Mean Pulmonary Arterial Pressure ◽  
Pulmonary Arterial

Pulmonary pressor response after prostaglandin synthesis inhibition in conscious dogs

1982 ◽  
Vol 52 (3) ◽  
pp. 705-709 ◽  
Author(s):  
B. R. Walker ◽  
N. F. Voelkel ◽  
J. T. Reeves
Keyword(s):  
Cardiac Output ◽  
Arterial Pressure ◽  
Pulmonary Arterial Pressure ◽  
Pressor Response ◽  
Conscious Dogs ◽  
Pulmonary Pressure ◽  
Time Control ◽  
Mean Pulmonary Arterial Pressure ◽  
Before And After ◽  
Pulmonary Arterial

Recent studies have shown that vasodilator prostaglandins are continually produced by the isolated rat lung. We postulated that these vasodilators may contribute to maintenance of normal low pulmonary arterial pressure. Pulmonary pressure and cardiac output were measured in conscious dogs prior to and 30 to 60 min following administration of meclofenamate (2 mg/kg iv, followed by infusion at 2 mg . kg-1 . h-1) or the structurally dissimilar inhibitor RO–20–5720 (1 mg/kg iv, followed by infusion at 1 mg . kg-1 . h-1). The animals were also made hypoxic with inhalation of 10% O2 before and after inhibition. Time-control experiments were conducted in which only the saline vehicle was administered. Meclofenamate or RO–20–5720 caused an increase in mean pulmonary arterial pressure and total pulmonary resistance. Cardiac output and systemic pressure were unaffected. The mild hypoxic pulmonary pressor response observed was not affected by meclofenamate. Animals breathing 30% O2 to offset Denver's altitude also demonstrated increased pulmonary pressure and resistance when given meclofenamate. It is concluded that endogenous vasodilator prostaglandins may contribute to normal, low vascular tone in the pulmonary circulation.

scholarly journals Pulmonary Vasodilator Therapy in Children with Single Ventricle Physiology: Effects on Saturation and Pulmonary Arterial Pressure

2020 ◽  
Vol 41 (8) ◽  
pp. 1651-1659
Author(s):  
Ida Jeremiasen ◽  
Karin Tran-Lundmark ◽  
Nikmah Idris ◽  
Phan-Kiet Tran ◽  
Shahin Moledina
Keyword(s):  
Arterial Pressure ◽  
Single Ventricle ◽  
Pulmonary Arterial Pressure ◽  
Vasodilator Therapy ◽  
Single Ventricle Physiology ◽  
Pulmonary Vasodilators ◽  
Mean Pulmonary Arterial Pressure ◽  
Pulmonary Vasodilator ◽  
Pulmonary Arterial ◽  
Stage 1

AbstractIn children with single ventricle physiology, increased pulmonary vascular resistance may impede surgical progression or result in failing single ventricle physiology. The use of pulmonary vasodilators has been suggested as a potential therapy. However, knowledge on indication, dosage, and effect is limited. A retrospective case notes review of all (n = 36) children with single ventricle physiology, treated with pulmonary vasodilators by the UK Pulmonary Hypertension Service for Children 2004–2017. Therapy was initiated in Stage 1 (n = 12), Glenn (n = 8), or TCPC (n = 16). Treatment indications were high mean pulmonary arterial pressure, cyanosis, reduced exercise tolerance, protein-losing enteropathy, ascites, or plastic bronchitis. Average dose of sildenafil was 2.0 mg/kg/day and bosentan was 3.3 mg/kg/day. 56% had combination therapy. Therapy was associated with a reduction of the mean pulmonary arterial pressure from 19 to 14 mmHg (n = 17, p < 0.01). Initial therapy with one or two vasodilators was associated with an increase in the mean saturation from 80 to 85%, (n = 16, p < 0.01). Adding a second vasodilator did not give significant additional effect. 5 of 12 patients progressed from Stage 1 to Glenn, Kawashima, or TCPC, and 2 of 8 from Glenn to TCPC during a mean follow-up time of 4.7 years (0–12.8). Bosentan was discontinued in 57% and sildenafil in 14% of treated patients and saturations remained stable. Pulmonary vasodilator therapy was well tolerated and associated with improvements in saturation and mean pulmonary arterial pressure in children with single ventricle physiology. It appears safe to discontinue when no clear benefit is observed.

Gestational resistance to the pulmonary vasoconstrictor effect of the TxA2 mimetic U-46619: possible mechanism

1997 ◽  
Vol 272 (6) ◽  
pp. R1734-R1739 ◽  
Author(s):  
G. Losonczy ◽  
G. Brown ◽  
I. Mucha ◽  
R. Klocke ◽  
V. Muller ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Pulmonary Arterial Pressure ◽  
Vascular System ◽  
Late Gestation ◽  
Mechanically Ventilated ◽  
Mean Pulmonary Arterial Pressure ◽  
Vascular Sensitivity ◽  
Specific Receptors ◽  
Pulmonary Arterial ◽  
Dose Dependent

Pregnancy is associated with the reduction of vascular sensitivity to vasoconstrictor compounds. We have examined whether pregnancy in rabbits induces hyposensitivity of the pulmonary vascular system to U-46619. Anesthetized, mechanically ventilated nonpregnant (NP; n = 7) and late-pregnant (P; n = 7) rabbits were studied. The intravenous injection of 0.03, 0.1, and 0.3 microgram/kg U-46619 led to a dose-dependent elevation of mean pulmonary arterial pressure (MPAP) in NP rabbits from a baseline value of 15 +/- 1 to 22 +/- 1 mgHg. There was no significant MPAP response to intravenous administration of U-46619 in P rabbits. The pulmonary arterial pressure response of isolated, ventilated, and buffer-perfused lungs of P rabbits was also blunted (P < 0.001 vs. NP). Pulmonary arterial membrane binding of [125I]BOP, another thromboxane (Tx)A2 analog, indicated 48 +/- 16 fmol receptors/mg protein in P rabbits and 193 +/- 48 fmol receptors/mg protein in NP samples (P < 0.025). Receptor affinity [1/dissociation constant (KD)] was also lower in the tissue of P rabbits (P < 0.01 vs. NP). The urinary excretion of the stable TxA2 metabolite 11-dehydro-TxB2 was lower in P than in NP rabbits (P < 0.02), which made homologous desensitization an unlikely explanation for the changes of vascular TxA2 receptors. These results show that, in late gestation, rabbit pulmonary vascular sensitivity to U-46619 is reduced simultaneously with, and as a possible consequence of, downregulation of specific receptors.

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