Trendelenburg positioning after cardiac surgery: effects on intrathoracic blood volume index and cardiac performance
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D. A. Reuter a1, T. W. Felbinger a1, C. Schmidt a1, K. Moerstedt a1, E. Kilger a1, P. Lamm a2 and A. E. Goetz a1c1
European Journal of Anaesthesiology
Background and objective: The efficacy of the Trendelenburg position, a common first step to treat suspected hypovolaemia, remains controversial. We evaluated its haemodynamic effects on cardiac preload and performance in patients after cardiac surgery.
Methods: Twelve patients undergoing mechanical ventilation of the lungs who demonstrated left ventricular kissing papillary muscles by transoesophageal echocardiography, thus suggesting hypovolaemia, were positioned 30° head down for 15 min immediately after cardiac surgery. Cardiac output by thermodilution, central venous pressure, pulmonary artery occlusion pressure, left ventricular end-diastolic area by transoesophageal echocardiography and intrathoracic blood volume by thermo- and dye dilution were determined before, during and after this Trendelenburg manoeuvre.
Results: Trendelenburg's manoeuvre was associated with increases in central venous pressure (9 ± 2 to 12 ± 3 mmHg) and pulmonary artery occlusion pressure (8 ± 2 to 11 ± 3 mmHg). The intrathoracic blood volume index increased slightly (dye dilution from 836 ± 129 to 872 ± 112 mL m−2; thermodilution from 823 ± 129 to 850 ± 131 mL m−2) as did the left ventricular end-diastolic area index (7.5 ± 2.1 to 8.1 ± 1.7 cm2 m−2), whereas mean arterial pressure and the cardiac index did not change significantly. After supine repositioning, the cardiac index decreased significantly below baseline (3.0 ± 0.6 versus 3.5 ± 0.8 L min−1 m−2) as did mean arterial pressure (76 ± 12 versus 85 ± 11 mmHg), central venous pressure (8 ± 2 mmHg) and pulmonary artery occlusion pressure (6 ± 4 mmHg). The intrathoracic blood volume index and left ventricular end-diastolic area index did not differ significantly from baseline.
Conclusions: Trendelenburg's manoeuvre caused only a slight increase of preload volume, despite marked increases in cardiac-filling pressures, without significantly improving cardiac performance.
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Effects of mild Trendelenburg on central hemodynamics and internal jugular vein velocity, cross-sectional area, and flow
Chikanori Terai MD, Hiroyuki Anada MD, Shunsuke Matsushima MD, Shoichiro Shimizu MD and Yoshiaki Okada MD
From the Department of Traumatology and Emergency Medicine, National Defense Medical College, Saitama, Japan
Received 24 May 1994; accepted 4 November 1994. Available online 2 August 2004.
Abstract
Despite widespread use of the Trendelenburg position, its autotransfusion effect remains controversial. Additionally, its adverse effect on cerebral circulation is not generally appreciated. The effects of a 10° head-down tilt on central hemodynamics and flow through the internal jugular vein (IJV) were examined in ten healthy volunteers. Left ventricular end-diastolic volume (LVEDV) and cardiac output (CO) were calculated from two-dimensional echocardiograms. IJV velocity and cross-section area were determined by the pulsed Doppler system. Measurements were made with the subjects in the supine position and at 1 minute and 10 minutes after tilting. A significant increase (16%) in CO followed by the increase in LVEDV was observed at 1 minute after tilting, although these changes disappeared after 10 minutes of tilting. Mean arterial pressure at the heart level did not change during the maneuver. The IJV velocity decreased whereas the IJV cross-sectional area increased at 1 minute after tilting, but both factors returned to control level at 10 minutes after tilting. As a result, calculated IJV blood flow was unchanged throughout the period of tilt. Therefore, the mild Trendelenburg position produces a transient autotransfusion effect in normovolemic patients. Out data also suggest that the Trendelenburg produces no adverse effect on cerebral circulation in patients with normal cerebral autoregulation.
