Bainbridge reflex

The Bainbridge reflex is a 1915 from the English physiologist Francis Arthur Bainbridge (1874-1921) described reflex , in which, after a sudden increase in blood volume ( infusion of saline or blood transfusion ) an increase in heart rate was observed. This effect was detectable with different arterial blood pressure , but dependent on the stretching of the right atrium of the heart (with an increase in central venous pressure) and an intact nerve connection to the circulatory center (vagus nerve).

It was later discovered that the reflex response depends on the initial situation: If the number of beats is low ( bradycardia ), volume increases the heart rate, but this decreases if the same occurs at a high initial rate ( tachycardia ).

The reason for this is the increased pressure in the right atrium due to the increase in blood volume. This triggers two antagonistic reflex patterns:

Expansion of receptors in the atrium stimulates the sinus node via the Bainbridge reflex and increases the frequency.
The Frank Starling mechanism also increases the stroke volume and thus the (systolic) blood pressure. The baroreceptor reflex then inhibits the sinus node and has a frequency-lowering effect.

This results in a double feedback loop with opposing frequency effects. Which effect predominates depends on the current circulatory situation - especially the blood volume:

If the blood volume is low (after blood loss), the stroke volume increases as the circulation fills up - in the direction of normovolemia (infusion therapy!) - and the heart rate decreases at the same time (baroreceptor reflex).
With increased blood volume ( hypervolaemia ), on the other hand, a further increase in volume no longer causes an increase in the stroke volume, but tachycardia (Bainbridge reflex) does. As a result, the heart "tries" to "work off" the high blood supply via the beat frequency.

The two reflexes complement each other so that they bring the circulation into the optimal middle range.

literature

Erich Schütz : Physiology of the heart. Springer, Berlin / Heidelberg 1958, OCLC 5935888 .

Individual evidence

↑ ^a ^b ^c Erich Schütz: Physiology of the heart. Springer, Berlin and Heidelberg 1958, p. 157 ff., P. 499.
^ Franz Kehl, Hans-Joachim Wilke: Anesthesia. Questions and Answers: 1500 facts for the specialist examination and the European Diploma in Anaesthesiology and Intensive Care Medicine (DEAA). Springer, 2013, ISBN 978-3-662-05729-2 . P. 517.

[schütz-1] Erich Schütz: Physiology of the heart. Springer, Berlin and Heidelberg 1958, p. 157 ff., P. 499.

[2] Franz Kehl, Hans-Joachim Wilke: Anesthesia. Questions and Answers: 1500 facts for the specialist examination and the European Diploma in Anaesthesiology and Intensive Care Medicine (DEAA). Springer, 2013, ISBN 978-3-662-05729-2 . P. 517.