Apnoea as a cardiotonic

Apnoea as a cardiotonic? It’s a strong statement but seems correct. It comes from the findings of research carried out by Claudio Passino of the Institute for clinical physiology (Ifc) of the Cnr of Pisa (Italy), which analysed the physiological adaptations of the cardiovascular and nervous systems of held-breath athletes who participated in the world records for straight held-breath diving under ice.

The research established how normal cardiovascular reflexes evoked away from immersion, cold and apnoea are activated simultaneously and reinforce each other in the “extreme” condition of immersion in cold water. Such reflexes are associated with periferal vasoconstriction which concentrates the flow of blood to the vital organs, limiting the consumption of oxygen by the organism and reducing the risk of hypoxia.

Examining the athletes more closely and positioning them in relation to non practicing subjects, it was immediately visible how in the former the sensibility of the chemoceptors (placed to check the organic variations of carbon dioxide, oxygen and pH in the blood) to hypoxia is lower.

This data is significant as to how chemoreflex may be “trained”, or adapted to situations of a lack of oxygen in order to cause it “alarm” after a longer time. The data highlights its importance if you think that one of the rousing causes of cardiac decompensations is actually the hyperactivity of chemoreflex which provokes dispnoea or “hunger for air”. The discovery could be useful for buffering cardiac decompensations with non pharmacological methods.

Credits: Claudio Passino, Institute of clinical physiology of the Cnr of Pisa.