Right atrial pressure and venous return during cardiopulmonary bypass

• The relevance of right atrial pressure (RAP) as the backpressure for venous return (QVR) and mean systemic filling pressure as upstream pressure is controversial during dynamic changes of circulation. To examine the immediate response of QVR (sum of caval vein flows) to changes in RAP and pump function, we used a closed-chest, central cannulation, heart bypass porcine preparation (n ± 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 QVR were studied using variable pump speed at constant airway pressure (PAW) and constant pump speed at variable PAW. Within each volume state, the immediate changes in QVR and RAP could be described with a single linear regression, regardless of whether RAP was altered by pump speed or PAW (r2 ± 0.586–0.984). RAP was inversely proportional to pump speed from zero to maximum flow (r2 ± 0.859– 0.999). Changing PAW caused immediate, transient, directionally opposite changes in RAP and QVR (RAP: P ≤ 0.002 and QVR: P ≤ 0.001), where the initial response was proportional to the change in QVR driving pressure. Changes in PAW 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 QVR and that Guyton’s model of circulatory equilibrium qualitatively predicts the dynamic response from changing RAP. NEW & NOTEWORTHY 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. © 2017 the American Physiological Society.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Kardiologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Cardiac and Cardiovascular Systems (hsv//eng)

Nyckelord

Cardiac output

Extracorporeal membrane oxygenation

Mean systemic filling pressure

Right atrial pressure

Venous return

adaptation

animal

animal model

artificial ventilation

biological model

cardiopulmonary bypass

circulation

extracorporeal oxygenation

heart atrium function

heart atrium pressure

inferior cava vein

ligation

physiology

pig

pulmonary artery

superior cava vein

surgery

time factor

Adaptation

Physiological

Animals

Atrial Function

Right

Atrial Pressure

Blood Circulation

Models

Animal

Models

Cardiovascular

Respiration

Artificial

Sus scrofa

Time Factors

Vena Cava

Inferior

Vena Cava

Superior

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)