In healthy humans, stroke volume (SV) and cardiac output (CO) do not increase with expansion of the central blood volume by head-down tilt or administration of fluid. Here, we exposed 85 patients to Trendelenburg\u0027s position about one hour after surgery while cardiovascular variables were determined non-invasively by Modelflow. In Trendelenburg\u0027s position, SV (83 ± 19 versus 89 ± 20 ml) and CO (6·2 ± 1·8 versus 6·8 ± 1·8 l/min; both P\u003c0·05) increased, while heart rate (75 ± 15 versus 76 ± 14 b min-1 ) and mean arterial pressure were unaffected (84 ± 15 versus 84 ± 16 mmHg). For the 33 patients (39%) with a \u003e 10% increase in SV (from 78 ± 16 to 90 ± 17 ml) corresponding to an increase in CO from 5·9 ± 1·5 to 6·9 ± 1·6 l min-1 (P\u003c0·05) when tilted head-down, administration of 250 ml Ringer\u0027s lactate solution increased SV (to 88 ± 18 ml) and CO (to 6·8 ± 1·7 l min-1 ). In conclusion, determination of SV and/or CO in Trendelenburg\u0027s position can be used to evaluate whether a patient is in need of IV fluid as here exemplified after surgery.
May 4, 2017
Journal:
Clin Physiol Funct Imaging
Author:
Frost H, Mortensen CR, Secher NH, Nielsen Bay H
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