Bloodshift

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Under blood shift (also blood shift ) or blood shift meant a redistribution of blood from the extremities to the stomach and chest area, mainly in the lungs . The bloodshift is one of the effects of the diving reflex and the main reason why freediving is possible to depths far below the 30-40 meters, which was previously considered the limit.

Emergence

In the diving reflex, which is triggered when the body is submerged (submersion), the circular muscles in the blood vessels of the arms and legs contract and thus reduce the total volume of the blood vessels in the body. As a result, a greater proportion of the blood volume in the torso is displaced mainly into the pulmonary artery , which increases blood pressure ; the alveoli , however, shrink due to the increased pressure. The compression of blood vessels and alveoli of the lungs results in a negative pressure, which leads to a further influx of venous blood in the lungs. The blood vessels in the lungs expand as a result and fill the space created by the shrinkage of the lung alveoli.

Practical meaning

The maximum possible diving depth during apnea diving is mainly determined by the ratio of the total volume ( TLC ) of the lungs to the residual volume ( RV , approx. 1.5 liters). Since freediving involves a compression of the lungs that is dependent on the depth of the dive, diving physicians were of the opinion until the mid- 1950s that freediving below 40 meters led to a ruptured lung . Due to the enlargement of the lung capillaries, the blood shift leads to a simultaneous reduction in the residual volume and thus to an increase in the maximum possible diving depth. So far, a redistribution of about 1.53 liters of blood into the pulmonary blood vessels has been proven.

literature

  • Alfred A. Bove, Jefferson Carroll Davis: Bove and Davis' diving medicine. 4th edition, Saunders / Elsevier Health Sciences, 2004, ISBN 0-7216-9424-1
  • Claus-Martin Muth, Peter Rademacher: Compendium of diving medicine. 2nd edition, Deutscher Ärzteverlag, Cologne 2007, ISBN 978-3-7691-1239-9

Individual evidence

  1. ↑ a b c Claus-Martin Muth: Apnea diving - Are there any medical specialties? ( Memento of March 4, 2016 in the Internet Archive ) (PDF; 146 kB) 8th Bonn Diving Symposium, February 23, 2008.