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The Trendelenberg Position and Shock Management

November 2, 2010

For about a century or more, clinicians have placed patients who are in circulatory shock into the Trendelenberg position, which is accomplished by tilting the patient’s bed into a head down position.  It was thought that by having the legs higher than the heart, there would be an improvement in venous return for cardiac filling, thereby resuscitating the circulation.  The procedure appeared to raise the low blood pressure to more acceptable levels, suggesting that cardiac output was improved.  Physicians and nurses have been doing so ever since, believing that such a procedure was a life-saving intervention.  Disappointingly, there has never been any evidence that this practice alters outcome whatsoever.

On the other hand, there is data that suggests the Trendelenberg position does not actually improve cardiac output in patients in shock.  In fact, the position could worsen their condition, despite the fact that the blood pressure is improved.  In 1979, Sibbald performed a study of the hemodynamic effects of Trendelenburg position in 61 normotensive and 15 hypotensive patients with acute cardiac illness or sepsis; no beneficial hemodynamic effects were observed.  A more recent meta-analysis found adverse consequences to the use of the Trendelenburg position and recommended it be avoided.

It is not clear if the gravitational impact of a head-down position improves blood flow to the brain.  Conceptually, it would potentially increase both the arterial and venous pressures.  Therefore, it is quite possible that it may pool more blood in the brain, without really circulating it.  This should then increase the intracranial pressure, which could be harmful in head injured patients.

Why do physicians and nurses still put patients into the Trendelenberg position when hypotension develops?  Has solid physiologic work escaped their attention?  It would be a real paradigm shift in medicine if physiology were to be the foundation for our actions instead of blind tradition.

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