Letter to the Editor

PEDIATRICS ◽  
1974 ◽  
Vol 53 (2) ◽  
pp. 289-289
Author(s):  
John Kattwinkel ◽  
Avroy A. Fanaroff ◽  
Marshall H. Klaus
Keyword(s):  
Cardiac Output ◽  
Venous Return ◽  
Blood Gases ◽  
Lung Compliance ◽  
Nasal Cpap ◽  
Vascular Space ◽  
Letter To The Editor

Initially, our procedure in instituting nasal CPAP was to start with a pressure of 6 cm H2O and increase gradually as blood gases dictated. Our concern was that in some infants, higher pressures might impede venous return thus compromising cardiac output. However, experience shows that if the technique is reserved for only patients with severe RDS (i.e., PaO2 < 60 mm Hg in FiO2 ≥ 70%) their lung compliance is low and transmission of pressure to the vascular space is probably negligible.

Quantitation of right-to-left shunting by double indicator and oxygen techniques

1976 ◽  
Vol 41 (3) ◽  
pp. 409-415 ◽  
Author(s):  
D. P. Copley ◽  
R. A. Klocke ◽  
F. J. Klocke
Keyword(s):  
Cardiac Output ◽  
Sulfur Hexafluoride ◽  
Venous Return ◽  
Right Heart ◽  
Indocyanine Green Dye ◽  
Arterial Blood ◽  
Vascular Space ◽  
Systemic Venous Return ◽  
Low Solubility ◽  
Right Heart Bypass

An improved double indicator technique for quantitating right-to-left shunting has been validated in a canine right-heart bypass shunt model and compared to standard O2 shunt measurements in the same preparation. A bolus of dissolved sulfur hexafluoride (SF6) and indocyanine green dye (ICG) is injected into systemic venous return and a single, time-averaged arterial blood sample is collected during the initial circulation of indicators. Because of its low solubility, SF6 is eliminated essentially quantitatively from blood traversing gas-filled alveoli; correction for volatile tracer in arterial blood derived from nonshunt pathways in therefore unnecessary. ICG remains confined to the vascular space and SF6 is not lost in shunt pathways. Ratios of SF6-ICG shunt to directly measured shunt averaged 0.99 +/- 0.27 (SD) in 55 comparisons of shunts ranging from 2 to 25% of cardiac output; differences between actual and measured shunt averaged 0.5 +/- 2.9% of cardiac output. Simultaneously determined ratios of O2 shunt to directly measured shunt averaged 0.98 +/- 0.48 in 34 comparisons; differences between actual and measured shunt were 0.7 +/- 3.4% of cardiac output.

Alterations in Systemic Vascular Volume of the Dog in Response to Hexamethonium and Norepinephrine

1957 ◽  
Vol 191 (2) ◽  
pp. 283-286 ◽  
Author(s):  
John C. Rose ◽  
Edward D. Freis
Keyword(s):  
Cardiac Output ◽  
Venous Return ◽  
Cardiac Activity ◽  
Left Ventricular ◽  
Vascular Volume ◽  
Vasomotor Activity ◽  
Constant Output ◽  
Arteriolar Tone ◽  
Integrated Responses

A diaphragm pump of controlled constant output was substituted for the left ventricle in dogs. Left auricular blood was conducted to a reservoir, from which it was pumped into the thoracic aorta. Left ventricular by-pass was complete. Alterations in total vascular volume were continually monitored by observation of the pump reservoir level. Sympathetic blockade (hexamethonium) increased total vascular volume (mean 15%). This resulted in decreased venous return and decreased right ventricular output. Norepinephrine constricted the total vasculature and decreased vascular volume (mean 12%). This resulted in increased venous return and cardiac output. These experiments demonstrated the complex integrated responses of the total circulation to sympathetic vasomotor activity. The role of the sympathetic nervous system not only in the regulation of arteriolar tone and cardiac activity but also in adjusting total vascular volume and venous return was emphasized. Venous return, and hence cardiac output alterations accompanying systemic vasomotor activity can only be detected by continuous methods of flow measurement.

Pulmonary gas exchange during exercise in women: effects of exercise type and work increment

2000 ◽  
Vol 89 (2) ◽  
pp. 721-730 ◽  
Author(s):  
Susan R. Hopkins ◽  
Rebecca C. Barker ◽  
Tom D. Brutsaert ◽  
Timothy P. Gavin ◽  
Pauline Entin ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Gas Exchange ◽  
Blood Gases ◽  
Random Order ◽  
Pulmonary Gas Exchange ◽  
Male Athletes ◽  
Prediction Limit ◽  
Fast Running ◽  
Arterial Blood ◽  
Exercise Induced

Exercise-induced arterial hypoxemia (EIAH) has been reported in male athletes, particularly during fast-increment treadmill exercise protocols. Recent reports suggest a higher incidence in women. We hypothesized that 1-min incremental (fast) running (R) protocols would result in a lower arterial Po 2 (PaO2 ) than 5-min increment protocols (slow) or cycling exercise (C) and that women would experience greater EIAH than previously reported for men. Arterial blood gases, cardiac output, and metabolic data were obtained in 17 active women [mean maximal O2 uptake (V˙o 2 max) = 51 ml · kg−1 · min−1]. They were studied in random order (C or R), with a fastV˙o 2 max protocol. After recovery, the women performed 5 min of exercise at 30, 60, and 90% ofV˙o 2 max (slow). One week later, the other exercise mode (R or C) was similarly studied. There were no significant differences in V˙o 2 maxbetween R and C. Pulmonary gas exchange was similar at rest, 30%, and 60% of V˙o 2 max. At 90% ofV˙o 2 max, PaO2 was lower during R (mean ± SE = 94 ± 2 Torr) than during C (105 ± 2 Torr, P < 0.0001), as was ventilation (85.2 ± 3.8 vs. 98.2 ± 4.4 l/min btps, P < 0.0001) and cardiac output (19.1 ± 0.6 vs. 21.1 ± 1.0 l/min, P < 0.001). Arterial Pco 2 (32.0 ± 0.5 vs. 30.0 ± 0.6 Torr, P < 0.001) and alveolar-arterial O2 difference (A-aDo 2; 22 ± 2 vs. 16 ± 2 Torr, P < 0.0001) were greater during R. PaO2 and A-aDo 2 were similar between slow and fast. Nadir PaO2 was ≤80 Torr in four women (24%) but only during fast-R. In all subjects, PaO2 atV˙o 2 max was greater than the lower 95% prediction limit calculated from available data in men ( n = 72 C and 38 R) for both R and C. These data suggest intrinsic differences in gas exchange between R and C, due to differences in ventilation and also efficiency of gas exchange. The PaO2 responses to R and C exercise in our 17 subjects do not differ significantly from those previously observed in men.

Cardiorespiratory effects of rapid saline infusion in normal man

1975 ◽  
Vol 38 (5) ◽  
pp. 786-775 ◽  
Author(s):  
A. L. Muir ◽  
D. C. Flenley ◽  
B. J. Kirby ◽  
M. F. Sudlow ◽  
A. R. Guyatt ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Arterial Pressure ◽  
Pulmonary Arterial Pressure ◽  
Control Period ◽  
Lung Compliance ◽  
Saline Infusion ◽  
Tidal Range ◽  
Closing Volume ◽  
Rapid Infusion ◽  
Pulmonary Arterial

We have studied the cardiorespiratory effects of the rapid infusion (100 ml/min) of 2 liters of saline in four normal seated subjects. Cardiac output and pulmonary arterial pressure increased, while vital capacity (VC) and total lung capacity (TLC) decreased. There was an increase in closing volume (CV) without any detectable change in lung compliance or flow-volume characteristics. There was an increase in Pao2 during infusion period which can be related to better matching of ventilation to perfusion and to improved hemoglobin transport. In the recovery stage as cardiac output, pulmonary arterial pressure, TLC, and VC all returned toward control values CV remained high. In two subjects CV occurred within the normal tidal range of ventilation and in these two subjects Pao2 fell significantly below values obtained in the control period. The results suggest that rapid saline infusion in man can cause interstitial edema and lead to premature airway closure and hypoxemia.

ASSESSMENT OF THE MATERNAL VENOUS CIRCULATION: WHY IS IT RELEVANT?

2013 ◽  
Vol 24 (3) ◽  
pp. 194-199
Author(s):  
KATHLEEN TOMSIN ◽  
WILFRIED GYSELAERS
Keyword(s):  
Cardiac Output ◽  
Organ Dysfunction ◽  
Venous Return ◽  
Cardiovascular Disorder ◽  
Systemic Circulation ◽  
Renal Vein Thrombosis ◽  
Venous System ◽  
Total Blood ◽  
Venous Circulation ◽  
Cardiovascular Assessment

The venous system is considered the main capacitor of the human body. Approximately 70% of the total blood volume resides in the venous bed, half of which circulates as venous return whereas the other half functions as reserve volume in the splanchnic veins. These veins are richly innervated and highly compliant, and communicate with the systemic circulation via capillaries (entrance) and portal vein and liver (exit). This constitution allows the venous compartment to balance circulating and stored blood volumes, and thus control cardiac output. Clinical conditions with reduced cardiac output are often associated with hampered venous return, resulting in visceral oedema, ascites or organ dysfunction. Organ dysfunction or failure may also result from (sub)obstructed venous outflow, as is illustrated in renal vein thrombosis or in the Nutcracker syndrome. Recently, the application of Doppler ultrasonography in the study of the maternal venous system illustrated that preeclampsia is another cardiovascular disorder with dysfunctional venous haemodynamics. In this opinion paper, we summarise results from Doppler studies of the maternal venous compartment, illustrating that performing venous haemodynamics function tests is to become a fundamental part of an integrated cardiovascular assessment of women with hypertension in pregnancy, facilitating an individualised diagnostic and therapeutic approach for every woman at risk for gestational hypertensive disease.

Sign in / Sign up

Export Citation Format

Share Document