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Passive leg raise, also known as shock position, is a treatment for shock or a test to evaluate the need for further fluid resuscitation in a critically ill person.[1]

Passive leg raise
Medical diagnostics
The five key points for a reliable passive leg raising test
SynonymsShock position

It is the position of a person who is lying flat on their back with the legs elevated approximately 8-12 inches.[2][3][4][5] The purpose of the position is to elevate the legs above the heart in a manner that will help blood flow to the heart.

This test involves raising the legs of a person's (without their active participation), which causes gravity to pull blood from the legs, thus increasing circulatory volume available to the heart (cardiac preload) by around 150-300 milliliters, depending on the amount of venous reservoir.[1] The real-time effects of this maneuver on hemodynamic parameters such as blood pressure and heart rate are used to guide the decision whether or not more fluid will be beneficial.[6][7] The assessment is easier when invasive monitoring is present (such as an arterial catheter).

The maneuver might be reinforced in a clinical setting by moving the patient's bed from a semi-recumbent position to a recumbent position with the legs raised. This is theorised to cause an additional mobilisation of blood from the gastrointestinal circulation.[8][9] Direct measurement of cardiac output is the more reliable comparing to the measurement of blood pressure or pulse pressure because of pulse pressure amplification during this procedure. Cardiac output can be measured by arterial pulse contour analysis, echocardiography, esophageal Doppler, or contour analysis of the volume clamp-derived arterial pressure. Any bronchial secretions must be aspirated before performing this test. The legs should not be elevated manually because it may provoke pain, discomfort, or awakening that can cause adrenergic stimulation, giving false readings of cardiac output by increasing heart rate. After the maneuver, the bed should be placed back into semi-recumbent position with cardiac output measured again. The cardiac output should return to the values measured before the initiation of this maneuver. This test can be can used to access fluid responsiveness without any fluid challenge, where the latter can lead to fluid overload.[10] Compression stockings should be removed before the test so that adequate volume of blood will return to the right heart during the maneuver.[11] The physiology of assessing fluid responsiveness via passive leg raise requires increasing systemic venous return without altering cardiac function - a form of functional hemodynamic monitoring.[12]

Several studies showed that this measure is a better predictor of response to rapid fluid loading than other tests such as respiratory variation in pulse pressure or echocardiographic markers.[12]

Placing the person in the Trendelenburg position, does not work since bloodvessels are highly compliant, and expand as result of the increased volume locally. More suitable would be the use of vasopressors.[2][3][4][5]

ReferencesEdit

  1. ^ a b Monnet X, Teboul JL (April 2008). "Passive leg raising". Intensive Care Med. 34 (4): 659–63. doi:10.1007/s00134-008-0994-y. PMID 18214429.
  2. ^ a b Irwin, Richard S.; Rippe, James M. (January 2003). Intensive Care Medicine. Lippincott Williams & Wilkins, Philadelphia & London. ISBN 978-0-7817-3548-3. Archived from the original on 2005-11-07.
  3. ^ a b Marino, Paul L. (September 2006). The ICU Book. Lippincott Williams & Wilkins, Philadelphia & London. ISBN 978-0-7817-4802-5.
  4. ^ a b "Fundamental Critical Care Support, A standardized curriculum of Critical Care". Society of Critical Care Medicine, Des Plaines, Illinois.
  5. ^ a b Harrison's Principles of Internal Medicine. Archived from the original on 2012-08-04.
  6. ^ Boulain T, Achard JM, Teboul JL, Richard C, Perrotin D, Ginies G (April 2002). "Changes in BP induced by passive leg raising predict response to fluid loading in critically ill patients". Chest. 121 (4): 1245–52. doi:10.1378/chest.121.4.1245. PMID 11948060.
  7. ^ Maizel J, Airapetian N, Lorne E, Tribouilloy C, Massy Z, Slama M (July 2007). "Diagnosis of central hypovolemia by using passive leg raising". Intensive Care Med. 33 (7): 1133–8. doi:10.1007/s00134-007-0642-y. PMID 17508202.
  8. ^ Jabot J, Teboul JL, Richard C, Monnet X (September 2008). "Passive leg raising for predicting fluid responsiveness: importance of the postural change". Intensive Care Med. 35 (1): 85–90. doi:10.1007/s00134-008-1293-3. PMID 18795254.
  9. ^ Teboul JL, Monnet X (June 2008). "Prediction of volume responsiveness in critically ill patients with spontaneous breathing activity". Curr Opin Crit Care. 14 (3): 334–9. doi:10.1097/MCC.0b013e3282fd6e1e. PMID 18467896.
  10. ^ Xavier, Monnet (14 January 2015). "Passive leg raising: five rules, not a drop of fluid!". Critical Care. 19 (18): 237. doi:10.1186/s13054-014-0708-5. PMC 4293822. PMID 25658678.
  11. ^ Jacob Chakco, Cyril; P Wise, Matt; J Frost, Paul (1 June 2015). "Passive leg raising and compression stockings: a note of caution". Critical Care. 19 (237): 237. doi:10.1186/s13054-015-0955-0. PMC 4450449. PMID 26028257.
  12. ^ a b Monnet, X; Marik, PE; Teboul, JL (December 2016). "Prediction of fluid responsiveness: an update". Annals of Intensive Care. 6 (1): 111. doi:10.1186/s13613-016-0216-7. PMC 5114218. PMID 27858374.

See alsoEdit