The Trendelenburg myth


CarolinaFireJournal - Bradley Dean
Bradley Dean
07/25/2010 -

Sometimes the science and the street have trouble communicating. The Trendelenburg position was originally used to improve surgical exposure of the pelvic organs, credited to the German surgeon Friedrick Trendelenburg (1844-1924). During World War I, Walter Cannon, an American physiologist, made the Trendelenburg position popular as a treatment for shock.  With the person being placed with their head down and feet elevated, he promoted it as a way to increase venous return to the heart, increase cardiac output and improve vital organ perfusion. 

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The Trendelenburg position is still a pervasive treatment for shock.

There was no science to prove what Cannon had claimed, yet the popularization had spread and was being accepted as common practice. A decade later, Cannon reversed his opinion regarding the use of the Trendelenburg position, but this did not deter the widespread use. It seems that the Trendelenburg position is still a pervasive treatment for shock despite numerous studies failing to show effectiveness. I have even heard Paramedics swear that it works, but these are only claims that cannot be backed by any scientific evidence without any other clinical treatment that may have added to the coincidental improvement in the patient.

Throughout the literature there are about 30 articles published concerning the Trendelenburg position, of which nine are peer reviewed. The common theme present in all these studies is that both normotensive, and hypotensive patients, the Trendelenburg position increases venous pressure, but did not result in significant improvement in systolic pressure. Those patients with cardiogenic shock experienced worsening pulmonary edema.

Others in the field have suggested that using a modified Trendelenburg position where the patient is kept flat and the legs are raised above the heart works.  The belief is that this “auto-transfuses” the patient with blood. The research does not support this theory either.  The volume of blood that drains from the lower extremities in the hypovolemic patient is minimal and does not result in any significant rise in blood pressure.

When you consider that aspiration is a greater risk when the patient is in the Trendelenburg position, the abdominal organs are displace up against the diaphragm restricting it’s movement, and the lack of research supporting its use, perhaps it is time to consider other options. One exciting option is an impedance threshold device called the Res-Q-Guard. This device is made for spontaneously breathing patients and works with the negative pressure inhalation providing greater dilation of the vena cava allowing for greater preload, and allowing for greater cardiac output.  Perhaps it is time we started treating our patients based more on science than on some 150-year-old ritualized procedures — just because the street can’t communicate with the science.

 

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