A couple of nights ago I saw an 83 y/o lady with septic shock. She presented in the same way the typical septic patient presents - looking bad and with the blood pressure in the toilet. I think her SBP was in the upper 50's. Not good! Her nurse, who is very smart and proactive, quickly started the IV's, hooked the monitor and tilted the bed in Trendelenburg position.
Trendelenburg position, a time-tested maneuver for the hypotensive patients, has been taught for generations of med students and nurses. It is written in text books and very commonly practiced. After all, it makes sense. If the BP is so low and we want to maintain cerebral perfusion and good cardiac output, tilting the head to a lower level than the rest of the body should be good, right? The problem is... that this well-intentioned maneuver does exactly the opposite of what it is intended for.
Let's think patophysiology just for few seconds, shall we?
When a patient is in supine position, raising the legs (and leaving the trunk flat) will cause an "auto-transfusion" with blood from the legs entering the central circulations and according to the Frank-Starling law, the heart will be able to pump that extra volume resulting in a temporary increase in cardiac output. (http://www.annalsofintensivecare.com/content/1/1/1 middle of the page) The key word here is "temporary", baroreceptors make this a short-lived effect and the only use of this maneuver is to see if the patient will respond to volume loading. So, what happens when the legs go up and the head goes down? There are multiple things that occur... There is an increase of blood flow to the upper body (which is now in the lower level) but this effect is "temporary" because in a few seconds the central venous pressure will increase to a point that arterial flow will inevitably decreased. It basically creates a traffic jam of blood trying to flow back to the heart, but can't b/c the venous pressure is high. This is the same thing that happens when you do the yoga head stand and feel like your eyes will pop out of your face, that is the increase venous pressure, the same phenomenon happens in Trendelenburg just not as severe. Also, the effect of gravity will push the abdominal contents against the diaphragm reducing thoracic expansion, causing increased intrathoracic pressure decreasing venous return even more, preload and finally, cardiac output. Therefore... Trendelenburg is not an effective way to improve heart and cerebral perfusion, it actually lowers cerebral perfusion and cardiac output potentially making things worse.
Now, back to our lady...
When I came to the room, I placed her supine and even raised the head slightly (10 degrees is more comfortable than flat), grabbed the ultrasound to look at her IVC and noted it was almost collapsing. 5 liters of crystaloids later, IVC was full, SBP was in the low 100's and she looked a lot better.
Take home points
- Trendelenburg does not improve hemodynamics in hypotensive patients and it may cause harm.
- Other ways to assess fluid responsiveness should be used to guide resuscitation.
- Ultrasound ROCKS!
- It is time to tackle this "Tren" myth and share the love with other colleagues for the sake of our patients.
Here are just few reviews I found, in case you need some more reading about this topic.