Thursday, October 17, 2013

1873: The Trendelenburg position is born x

Probably just about every person in the medical profession is familiar with the trendelenburg position.  It's where you set the patients bed so that his hips are higher than his head.  Basically, you set him so that he's upside down. 

This is done for therapeutic reasons.  Respiratory therapists do it to aid in the drainage of secretions during chest physiotherapy.  Chest physiotherapy is where the therapist cups his hands and bangs on the patients chest to a rapid rhythm.  Vibrations supposedly help knock sections from the lungs. 

By placing the patient in trendelenburg, this allows the now loose secretions to flow to the upper airway, where they can be coughed up or suctioned out.  Patients who require such therapy are any patients with thick, tenacious secretions, such as bronchiectasis or cystic fibrosis.  Sometimes it's done for COPD patients too. 

Another use for trendelenburg is to help drain blood to the brain to increase blood pressure.  It seems that one of the first reactions when it's determined a person's blood pressure is critically low is to place the person in trendelenburg.  Yet one might wonder: does this really work to lower blood pressure?

The Trendelenburg position was first used in the mid 19th century by German physician and surgeon Fredrish Trendelenburg, according to AMargo A. Halm in her 2012 article in American Journal of Critical Care, "Trendelenburg Position: 'Put to Bed' or Angled Toward Use in Your Unit."  (1, page 449)

Halm explains that Trendelenburg used the "technique known in the Middle Ages as the "head-down position."  In his surgical text of 1873, Trendelenburg recognized that raising the patient's hips caused the bulk of abdominal viscera to slide toward the diaphragm, providing a less cluttered operative field for lower abdominal and pelvic procedures." (1, page 449)

It wasn't until the early 20th century that the position was used by physiologist Walter Cannot to "displace blood from the lower extremities to enhance venous return in the treatment of hemorrhagic shock.  This action was thought to cause an 'autotranfusion' to the central circulation, increasing right and left ventricular preloads, stroke volume, and cardiac output (CO)."  It would, thus, increase a patients blood pressure.  (1, page 449)

Use of Trendelenburg for raising blood pressure was questioned during the 1950s, but it became widespread anyway as a "mainstay of resuscitation."  Recently there have been studies that show the position does increase blood pressure, although the effect is only short term.  (1, page 449)

Halm notes that most studies conclude that "Trendelenburg position does not lead to beneficial changes in blood pressure or CO/CI..  As a result, this position is probably not useful in rescue efforts.  The associated hemodynamic effects are small and unsustained and thus are unlikely to have a clinically significant impact on hypotensive patients."

The study results, Halm writes, conclude that it's better to use other methods of reducing blood pressure, such as:
  • Fluid boluses
  • Pharmacological therapies
  • Other devices targeted to the cause of hypotension
Yet like any other procedure used by the medical profession, physicians aren't going to stop using something they've been doing for a long time.  Regardless of the evidence, physicians are going to continue doing something that simply sounds like a good idea. 

Yet Halm notes that this might not be such a good idea, because trendelenburg position can be "associated with harmful cardiopulmonary, neurological, and vascular effects, especially in the presence of disease." (1, page 451)

Side effects of trendelenburg include:
  • Anxiety
  • Restlessness
  • Onset of pounding headache
  • Progressive dyspnea
  • Loss of cooperation
  • Hostile patient
  • Struggling efforts to sit upright
Although, it would seem that many of these side effects would result in a ticked off patient, something that would almost assuredly increase blood pressure.  I once had a doctor order BiPAP for a patient just because he knew it would tick the patient off, and therefore raise blood pressure. 

She notes that "the position should be used with caution even when immediate/transient benefits are desired."  And I would have to add that the ethics of doing something that has no proven long term effect may work to the disadvantage of therapy.

I think the position would also be harmful when you have a patient in respiratory distress with a low blood pressure.  The temporary rise of blood pressure may come at the expense of making breathing exceedingly more difficult and uncomfortable for the patient. 

All this said, I have never had a patient complain about being in this position, and usually there sick enough, or medicated enough, not to care. 

References:
  1.  Halm, Margo A., RN, "Trendelenbug Position: 'Put to Bed' or Angled Toward Use in Your Unit," American Journal of Critical Care, November, 2012, Volume 21, No. 6, page 449-452, www.ajconline.org

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