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of treatment. In this study, SVV exhibited strong and right recumbent position did not change the hemodynamic
negative correlation with CI, SVI, GEF and GEDVI in septic data and SVV. The increased SVV induced by both the 30°
patients despite the fact that all variables were obtained head-up and prone positions could be attributed mostly to
from five various body positions. These results further the decrease in vena cava blood return[14,18]. The 30° head-
demonstrated that dynamic SVV was an effective predictor up and prone positions placed the heart on a hydrostatic
in functional hemodynamic monitoring, which agrees level above the head and limbs, which decreased vena
with numerous previous investigations demonstrating the cava return .[15-19] The mild abdominal compression in
usefulness of SVV in predicting fluid responsiveness in the prone position, and the downward movement of the
various subsets of ventilated patients[5,6,7,8,11,12,13]. Both SVV diaphragm in 30° head-up position, might induce inferior
and pressure pulse variation(PPV) are validated to predict vena cava compression, thereby decreasing vena cava blood
volume responsiveness in the prone position during spine return through increased intra-abdominal pressure[20].
surgery[14]. Consequently, the cyclic effect of mechanical ventilation on
the heart would be more pronounced because of a decrease
In the present study, both the 30° head-up and prone in vena cava blood return. We also found poor correlation
position led to a significant increase in SVV. Concomitantly, between SVV in the supine position and the CI changes
those two body positions reduced SVI, CI, GEF and central induced by the 30° head-up or prone positions, which
blood volume, as assessed by GEDVI, in agreement with suggested that altering body position induced changes in
previous studies. Biais et al[14] demonstrated that the prone SVV and CI that were not only preload-dependent but
position significantly increased SVV and PPV but did not might be implicated in other mechanisms. It has been
alter their ability to predict fluid responsiveness. Head-up demonstrated that increasing chest wall compliance by
tilt positions are associated with decreased thoracic fluid opening the chest decreased SVV[18]. Unfortunately, we did
content, SV and CO[15-17]. More interestingly, the 30° left or
Fig. 2 Individual SVV responses. SVVs for the 30° head-up Fig. 3 Correlation between SVV in the supine position with
position and the prone position were significantly higher than 30° head-up or prone position induced changes in CI.
those for the supine position.( the 30° head-up position: Figure
2a; the prone position :Figure 2d) The SVVs in the supine position did not correlate well with
changes in CI induced by the 30° head-up position(r=-0.119,
Individual SVV responses to the recumbent positions of SVV P>0.05) or prone position(r=-0.130, P>0.05)
to the 30° right recumbent position: SVV did not differ between
the 30° left recumbent or the 30° right recumbent position and
the supine position.(the 30°left recumbent position: Figure 2b;
the 30° right recumbent position: Figure 2c)
Laboratory and ClinicaCl IonvveersTtihgeastiiosn 96 FAM 2015 Mar/Apr Vol.22 Issue 2
