J Korean Soc Emerg Med.  2021 Dec;32(6):586-590.

Real-time measurement of changes in cardiac output that occur after raising the lower extremities in a supine position in healthy adults

• Suh JY
• Park SC
• Park SW
• Han SK
• Cho YM
• Bae BK

Abstract

Objective
Passive leg raising for treating patients with shock involves the elevation of the legs in the supine position and can also be applied to patients showing sudden aggravation after lying down for a certain period. A study involving healthy adults has reported that this type of passive leg raising is ineffective for those who spend a long time in the supine position. The study measured cardiac output intermittently using echocardiography rather than measuring it continuously in real time, making it impossible to examine the overall trend in cardiac output before and after the leg raise. This study aimed to examine changes and trends in cardiac output using a device that measures cardiac output in real time.
Methods
The present study was conducted from January to August 2020 and included healthy adults aged 18 years and above. Cardiac output was measured with a noninvasive cardiac output measuring device (electrical cardiometry, ICON) for 30 minutes in the supine position and for another 30 minutes in the supine position with the legs raised at 45° for 60 minutes.
Results
A total of 40 participants were included in the study. Cardiac output increased from 5.13±1.42 L/min to 5.14± 1.64 L/min after the passive leg raise. However, the increase was not statistically significant (P=0.958).
Conclusion
No statistically significant change was found between the cardiac outputs before the leg raise and after the leg raise.

Keyword

Passive leg raising; Cardiac output; Electrical cardiometry