Key result
Head-up and head-down tilt demonstrated that stroke volume changes with thoracic fluid content rather than central vascular pressures (SV decreased to 48 ± 21 ml at 50 min of HUT, P<0.001).
Why the study?
Does stroke volume correlate better with thoracic fluid content or central filling pressures during postural changes in healthy humans?
Observational (n=9)
Does stroke volume correlate better with thoracic fluid content or central filling pressures during postural changes in healthy humans?
Stroke volume correlates with thoracic fluid content rather than central filling pressures during postural changes, suggesting cardiac function relates more to volume than filling pressures.
Central pressures may mislead preload assessment during postural change; leaves open thoracic fluid content monitoring for stroke volume guidance.
BACKGROUND: The stroke volume (SV) of the heart depends on the diastolic volume but, for the intact organism, central pressures are applied widely to express the filling of the heart. METHODS: This study evaluates the interdependence of SV and thoracic electrical admittance of thoracic fluid content (TA) vs. the central venous (CVP), mean pulmonary artery (MPAP) and pulmonary artery wedge (PAWP) pressures during head-up (HUT) and head-down (HDT) tilt in nine healthy humans. RESULTS: From the supine position to 20 degrees HDT, SV [112 +/- 18 ml; mean +/- standard deviation (SD)], TA (30.8 +/- 7.1 mS) and CVP (3.6 +/- 0.9 mmHg) did not change significantly, whereas MPAP (from 13.9 +/- 2.7 to 16.1 +/- 2.5 mmHg) and PAWP (from 8.8 +/- 3.4 to 11.3 +/- 2.5 mmHg; P < 0.05) increased. Conversely, during 70 degrees HUT, SV (to 65 +/- 24 ml) decreased, together with CVP (to 0.9 +/- 1.4 mmHg; P < 0.001), MPAP (to 9.3 +/- 3.8 mmHg; P < 0.01), PAWP (to 0.7 +/- 3.3 mmHg; P < 0.001) and TA (to 26.7 +/- 6.8 mS; P < 0.01). However, from 20 to 50 min of HUT, SV decreased further (to 48 +/- 21 ml; P < 0.001), whereas the central pressures did not change significantly. CONCLUSIONS: During both HUT and HDT, SV of the heart changed with the thoracic fluid content rather than with the central vascular pressures. These findings confirm that the function of the heart relates to its volume rather than to its so-called filling pressures.
No takes yet. Share an insight, caveat, or question.
Lieshout et al. (2005) conducted an observational in Healthy (n=9). Head-up (HUT) and head-down (HDT) tilt vs. Supine position was evaluated on Interdependence of stroke volume (SV) and thoracic fluid content (TA) vs. central pressures (CVP, MPAP, PAWP). Head-up and head-down tilt demonstrated that stroke volume changes with thoracic fluid content rather than central vascular pressures (SV decreased to 48 ± 21 ml at 50 min of HUT, P<0.001).
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: