A 28 year-old female has hypovolaemic shock from a ruptured ectopic pregnancy. Her blood pressure is 68/35, pulse 124, and GCS 13/15. She has received 2 litres of Normal Saline with minimal response.
The senior registrar in the emergency department requests the patient be given 0.5mg IV metaraminol, and asks you to tilt the bed into the Trendelenburg position as a temporising measure untill blood products arrives and the patient is taken to the operating theatre.
As the patient is then rushed off to theatre, you wonder what does the Trendelenburg position actually do, and what is the evidence for it.
History of the Trendelenburg position
The Trendelenburg position involves placing the patient head down and elevating the feet. It is named after German surgeon Friedrich Trendelenburg, who created the position to improve surgical exposure of the pelvic organs during surgery.
In World War 1 , Walter Cannon, the famous American physiologist, popularized the use of Trendelenburg position as a treatment for shock. It was promoted as a way to increase venous return to the heart, increase cardiac output and improve organ perfusion. A decade later, Cannon reversed his opinion on the benefits of the Trendelenburg position but that did not deter its widespread use.
Today, the Trendelenburg position remains a time honoured tradition in the early management of the hypotensive patient. As we shall see, this is despite a flimsy evidence base.
What the Literature tells us about the Trendelenburg position
Shammas & Clark (2007) summarised the state-of-play regarding the use of the Trendelenburg position to treat acute hypotension as follows:
- Trendelenburg position is widely used by nurses and other healthcare providers as a first-line intervention in the treatment of acute hypotension and/or shock.
- A review of the results of 5 research studies did not provide overwhelming support for its use as a treatment of hypotension.
- When Trendelenburg positioning improved cardiac parameters, it was brief and was followed by haemodynamics deterioration that led to negative consequences.
- Adverse consequences were found in certain patient populations who were obese, had compromised right ventricular ejection fraction, a pulmonary disorder, or a head injury.
- The Trendelenburg position should be avoided as a treatment of acute hypotension/shock until definitive research with larger sample sizes is conducted that support its use as safe and effective.
Ostrow’s 1997 study of critical care nurses’ beliefs about the Trendelenburg position showed 99% of respondents had used the position, 28% believed it was always beneficial and 61% believed it was somewhat beneficial although they also recognised the complications from it.
Studies that have demonstrated an increase blood pressure and cardiac output are limited. When observed, the increase is generally short lived, lasting less than 10 minutes.
Current data to support the use of the Trendelenburg position during shock are limited and do not reveal any beneficial or sustained changes in systolic blood pressure or cardiac output.
Complications of the Trendelenburg position in the hypotensive patient
- Anxiety and restlessness
- Progressive dyspnea
- Hypoventilation and atelectasis caused by reduced respiratory expansion
- Altered ventilation/perfusion ratios from gravitation of blood to the poorly ventilated lung apices
- Increasing venous congestion within and outside the cranium leading to increased intracranial pressure
- Pressure from abdominal organs is transmitted into the thoracic cavity, which can impair venous return to the heart, leading to a further decreased cardiac output and hypotension
- Increase risk of aspirating gastric contents
When the Trendelenberg position should, and should not, be used
The Trendelenburg position is clinically useful for:
- Insertion or removal of central venous catheters
- Certain spinal anaesthetic techniques
The Trendelenburg position is probably not indicated or may have harmful effects in:
- Resuscitation of patients who are hypotensive
- Patients in whom mechanical ventilation is difficult, or patients with decreased vital capacity
- Patients who have increased intracranial pressure
- Patients who have cerebral oedema
- Patients who have increased intraocular pressure
- Patients with ischaemia of the lower limbs
What does the future hold for the Trendelenburg position?
Until further large randomised control studies show a benefit from the use of the Trendelenburg position, it should not be a part of routine practice. When confronted with a hypotensive patient your time and attention may be better spent thinknig about evidence limited, time honoured practices and dilemmas like whether to resuscitate the patient with crystalloid or colloid, or whether dopamine or noradrenaline should be used as a vasopressor…
“It is the mark of an educated mind to be able to entertain a thought without accepting it”.
Boulain, T. et.al. (2002). Changes in BP induced by passive leg raising predict response to fluid loading in critically ill patients. Chest. 121(4), 1245-1252. PMID: 11948060
Bridges, N.& Jarquin-Valdivia, A. (2005). Use of the Trendelenburg Position as the Resuscitation Position: To T or Not to T. American Journal of Critical Care. 14(5). 364-368. PMID: 16120887
Johnson, S. & Henderson, S. (2004). Myth: The Trendelenburg position improves circulation in cases of shock. Canadian Journal of Emergency Medicine. 6(1), 48-49. PMID: 17433146
Kettaneh, N. & Jones, J. (2008). Use of the Trendelenburg Position to Improve Haemodynamics during Hypovolaemic Shock. Accessed on 12, May, 2010 Bestsbets.org.
Ostrow, C. (1997). Use of the Trendelenburg position by critical care nurse: Trendelenburg survey. American Journal of Critical Care. 6, 172-176. PMID: 9131195
Shammas, A. & Clark, A. (2007). Trendelenburg Positioning to Treat Acute Hypotension: Helpful or Harmful? Clinical Nurse Specialist. 21(4), 181-188. PMID: 17622805