Reply to “Letter to the editor: Why persist in the fallacy that mean systemic pressure drives venous return?”

Berger, David; Möller, Per Werner; Takala, Jukka

doi:10.1152/ajpheart.00622.2016

Cited by 22 publications

(24 citation statements)

References 14 publications

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“…We have recently observed a rightward shift of VR curves during inspiratory hold maneuvers in an animal model with a beating heart (4), and we assumed that RAP acted as backpressure to VR during inspiratory holds (29,46). We were criticized for regarding the pressure difference between MSFP and RAP (the VR driving pressure) as relevant for Q VR (3,6): a central issue in the ongoing theoretical debate on the validity of Guyton's concept of circulation (7-9, 30, 31). The pulmonary circulation, its blood volume, and their respective effects on right heart function interact with the changes in the systemic circulation induced by changes in P AW (11,34,39,40,45), and they may have influenced our previous findings of VR curve shift.…”

Section: H414mentioning

confidence: 99%

“…Even those who oppose Guyton's model (1) agree that MSFP at zero flow should represent the elastic recoil pressure of the systemic vascular stressed volume (3,33). Stressed volume is redistributed along vascular beds during flow; nevertheless, it is still present, and so must be its related pressure, MSFP (3,25,32). One central question relates to the applicability of Guyton's VR model in the transit between steady states, a condition in which it is often used implicitly (40).…”

Section: H414mentioning

confidence: 99%

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Right atrial pressure and venous return during cardiopulmonary bypass

Moller

Winkler

Hurni

et al. 2017

American Journal of Physiology-Heart and Circulatory Physiology

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The relevance of right atrial pressure (RAP) as the backpressure for venous return (Q) and mean systemic filling pressure as upstream pressure is controversial during dynamic changes of circulation. To examine the immediate response of Q (sum of caval vein flows) to changes in RAP and pump function, we used a closed-chest, central cannulation, heart bypass porcine preparation ( = 10) with venoarterial extracorporeal membrane oxygenation. Mean systemic filling pressure was determined by clamping extracorporeal membrane oxygenation tubing with open or closed arteriovenous shunt at euvolemia, volume expansion (9.75 ml/kg hydroxyethyl starch), and hypovolemia (bleeding 19.5 ml/kg after volume expansion). The responses of RAP and Q were studied using variable pump speed at constant airway pressure (P) and constant pump speed at variable P Within each volume state, the immediate changes in Q and RAP could be described with a single linear regression, regardless of whether RAP was altered by pump speed or P ( = 0.586-0.984). RAP was inversely proportional to pump speed from zero to maximum flow ( = 0.859-0.999). Changing P caused immediate, transient, directionally opposite changes in RAP and Q (RAP: ≤ 0.002 and Q: ≤ 0.001), where the initial response was proportional to the change in Q driving pressure. Changes in P generated volume shifts into and out of the right atrium, but their effect on upstream pressure was negligible. Our findings support the concept that RAP acts as backpressure to Q and that Guyton's model of circulatory equilibrium qualitatively predicts the dynamic response from changing RAP. Venous return responds immediately to changes in right atrial pressure. Concomitant volume shifts within the systemic circulation due to an imbalance between cardiac output and venous return have negligible effects on mean systemic filling pressure. Guyton's model of circulatory equilibrium can qualitatively predict the resulting changes in dynamic conditions with right atrial pressure as backpressure to venous return.

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Section: H414mentioning

confidence: 99%

Section: H414mentioning

confidence: 99%

Right atrial pressure and venous return during cardiopulmonary bypass

Moller

Winkler

Hurni

et al. 2017

American Journal of Physiology-Heart and Circulatory Physiology

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“…Unfortunately, Prof. Brengelmann appears to ignore our published data and our interpretations. His current letter repeats issues that we have already responded to in detail in a point-by-point response following our first VR study (10). Very briefly, our response can be summarized as follows.…”

mentioning

confidence: 74%

Reply to “Is the Guytonian framework justified in explaining heart lung interactions?” and “Venous return, mean systemic pressure and getting the right answer for the wrong reason”

2019

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“…Gradient for VR is equal to the difference between mean systemic venous pressure (MSVP) and the right atrial pressure (RAP) (MSVP − RAP). 6,7 Elastic recoil of veins generates some positive pressure in venous blood that is called MSVP. Increase in intravascular volume or venous tone can increase MSVP.…”

Section: Right Ventricular Preloadmentioning

confidence: 99%

Heart–Lung Interaction

2018

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Mechanical interplay between respiratory and cardiac systems was first recognized about 300 years ago when an English physiologist Stephen Hales observed that the level of the blood column in a glass tube inserted into the carotid artery of a horse varied cyclically with respiration.Heart and lung share the same intrathoracic space, and mechanically this configuration is akin to pump within a pump. As a result, intrathoracic pressure (ITP) and volume changes during respiratory cycle affect the performance of heart. Besides direct mechanical effects, lung and heart interplay also involves certain neurally and humorally mediated phenomena. Taken together, these dynamics constitute heart–lung interaction. Knowledge of heart–lung interaction is especially useful while dealing with critically sick patients on ventilator, because not only are such patients more vulnerable to hemodynamic instability induced by ventilator, but it also forms the basis of functional hemodynamic monitoring.

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Reply to “Letter to the editor: Why persist in the fallacy that mean systemic pressure drives venous return?”

Cited by 22 publications

References 14 publications

Right atrial pressure and venous return during cardiopulmonary bypass

Right atrial pressure and venous return during cardiopulmonary bypass

Reply to “Is the Guytonian framework justified in explaining heart lung interactions?” and “Venous return, mean systemic pressure and getting the right answer for the wrong reason”

Heart–Lung Interaction

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