Related Experiment Video
Updated: Aug 21, 2026
Doppler Ultrasound-Based Leg Blood Flow Assessment During Single-Leg Knee-Extensor Exercise in an Uncontrolled Setting
Published on: December 15, 2023
Body position change and its effect on hemodynamic and metabolic status
Alice Y M Jones1, Elizabeth Dean
1Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Kowloon, Hong Kong.
Objective:
The study's objective was to examine the effect of body position on oxygen consumption (Vo(2)) and hemodynamics. Although gravity-dependent hemodynamic and pulmonary consequences are well documented, less is known about the effect of body positions on VO(2) and hemodynamics, which is of importance in critical care.
Design:
This was a quasi-experimental study.
Setting:
The setting was a physiology laboratory controlled for noise and temperature (21 degrees C).
Subjects:
Healthy, nonsmoking subjects were studied (n = 32; 18 women and 14 men aged 20 +/- 0.84 years [mean +/- SD]). Outcome measures After each subject was in each position of interest for 10 minutes, heart rate (HR), blood pressure (BP), rate pressure product (RPP) (an index of myocardial Vo(2) = HR x systolic BP), Vo(2). min. m(2), and arterial saturation (Spo(2)) were recorded for 10 minutes and averaged. All testing was conducted at midday.
Interventions:
Five body positions used in the intensive care unit were standardized and included the following: sitting in a firm chair with feet supported (sitting), horizontal supine flat position (H-S), head-down (30 degrees ) supine flat position (HD-S), and right- and left-side lying (90 degrees ) positions (RSL and LSL, respectively).
Results:
Generally, HR, BP, RPP, and Vo(2) were highest in the sitting position compared with the lying positions (P <.05) and lowest in the LSL position (P <.05). The H-S and HD-S positions tended to affect these variables comparably with the exception of HR, which was lowest in the H-S position and significantly lower in the HD-S positions (P <.05). Both systolic and diastolic BP were comparable in the sitting, H-S, and HD-S positions, and significantly lower in the RSL and LSL positions (P <.001). Similar to mean Vo(2), the mean RPP tended to be reduced across positions in the following sequence: sitting, HD-S, H-S, RSL, and LSL. Spo(2) did not change across body positions.
Conclusions:
These results yield further insight into how the adverse and beneficial effects of body positioning as a therapeutic intervention may be mediated through gravitational stress and myocardial mechanics. Such an understanding is crucial when prescribing body positioning to enhance oxygenation in the patient in the intensive care unit and to minimize its adverse effects.
Related Concept Videos
01:11Anatomical Positions
The body is upright, facing forward, and standing erect.
The feet are parallel and flat on the floor.
The arms are hanging by the...
01:24Blood Pressure Imbalances and Circulatory Shock
Blood Pressure: Hypertension and Hypotension
Normal blood pressure is 120/80 mm Hg. Elevated blood pressure is 120-129/under 80 mm Hg. Hypertension, warranting treatment at 130/80 mm Hg, is often asymptomatic and can lead to severe cardiovascular events, aneurysms, peripheral arterial disease, chronic renal disease, or cardiac...
01:28Special considerations while measuring blood pressure
Monitoring Both Arms:
Monitoring BP in both arms during the initial assessment is advisable, as the systolic value may differ by five to ten mm Hg between arms. For subsequent BP assessments, use the arm with the higher reading.
01:30Factors Influencing Heart Rate
Let us explore the significant factors affecting heart rate, including age, body temperature, posture, acute pain, chemical influences,...
01:30Alterations in Blood Pressure
Hypertension (High blood pressure)
Hypertension occurs when blood pressure readings consistently exceed the normal range. It is diagnosed when systolic blood pressure (the top number, indicating pressure while the heart beats)...
01:29Pathophysiology of Cardiac Performance