Passive leg raise

Not to be confused with Straight leg raise.

Passive leg raise
passive leg raising test
Synonyms	Shock position

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]

The position consists of a person lying flat on their back with their legs elevated 8–12 inches (200–300 mm). ^{[2] [3] [4] [5]} This is done to keep the legs above the heart, helping blood flow to the heart via gravity. This increases the volume of blood available to the heart (cardiac preload) by 150-300 milliliters. ^[1] The real-time effects of this on parameters such as blood pressure and heart rate guide decisions on if more fluid will be beneficial. ^{[6] [7]}

Passive leg raises may be reinforced in a clinical setting by moving the patient's bed from a semi-recumbent (half sitting, half laying down) position to a recumbent (laying down) position with the legs raised. This is theorised to cause additional mobilisation of blood from the gastrointestinal circulation. ^{[8] [9]}

The assessment is easier with invasive monitoring (such as an arterial catheter). 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 used to assess 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 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]}

See also

• Trendelenburg position

References

1. 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. 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. Marino, Paul L. (September 2006). The ICU Book. Lippincott Williams & Wilkins, Philadelphia & London. ISBN   978-0-7817-4802-5. Archived from the original on 2009-11-29. Retrieved 2018-10-24.
4. "Fundamental Critical Care Support, A standardized curriculum of Critical Care". Society of Critical Care Medicine, Des Plaines, Illinois. Archived from the original on 2007-09-28. Retrieved 2018-10-24.
5. 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. 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.