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Correspondence

Effects on left ventricular performance of changes in cardiac loading conditions depend on 'relative load'

Reuter, D. A.; Goetz, A. E.

Author Information
European Journal of Anaesthesiology: February 2004 - Volume 21 - Issue 2 - p 159-160

A reply

EDITOR:

We thank Drs De Hert and Van der Linden for their interesting comments on our recent article about the physiological changes in the Trendelenburg position [1]. We absolutely agree with their statement that 'manoeuvres intended to increase cardiac preload may elicit a variety of responses'. However, this study was primarily designed to investigate the effect of the Trendelenburg position on the effective blood volume that contributes to cardiac preloading in this specific clinical situation. The intrathoracic blood volume index has been shown to reflect adequately changes in that preload volume under fluid loading. On the other hand, Trendelenburg positioning has been used now for decades exactly in order to increase the preload volume by autotransfusion. However, results of studies regarding the efficacy of the Trendelenburg manoeuvre to increase the preload volume have been inconsistent. Therefore, the primary aim of our study was to investigate the potential increase in preload volume by the Trendelenburg manoeuvre using a volumetric measurement technique, namely the intrathoracic blood volume index. Our results support the contention that the Trendelenburg manoeuvre, at least in this specific clinical situation, does not cause that expected effect of autotransfusion in patients who are hypovolaemic as visualized by transoesophageal echocardiography.

However, certainly a head down-tilt position of 30° may elicit, as mentioned by Drs De Hert and Van der Linden, a variety of haemodynamic consequences - beyond any changes in preload volume - as sudden changes in left ventricular afterload, and the contractile response to these changes depend on the relative cardiac load [2-4]. As our patients were not instrumented with left ventricular conductance catheters (not feasible after operation in patients with closed chests in intensive care), this cannot finally be demonstrated. Hence, it is debatable whether the systolic and diastolic left ventricular pressure-volume relations point towards a deficient length-dependent regulation of myocardial function together with a low- or a high-relative cardiac load. However, using trans-oesophageal echocardiography, gross functional appearances did not point toward severe left ventricular dysfunction as evidenced by abnormalities of regional wall motion or a severely reduced pattern of contractility. We, therefore, fully agree with Drs De Hert and Van der Linden that these aspects should be further analysed using a greater number of patients as well as differentiating the effects of solitary leg elevation or tilting the whole patient head down.

D. A. Reuter

A. E. Goetz

Department of Anaesthesiology; University of Munich; Munich, Germany

References

1. Reuter DA, Felbinger TW, Schmidt C, et al. Trendelenburg positioning after cardiac surgery: effects on intrathoracic blood volume index and cardiac performance. Eur J Anaesthesiol 2003; 20: 17-20.
2. Gillebert TC, Leite-Moreira AF, De Hert SG. Relaxation-systolic pressure relation: a load-independent assessment of left ventricular contractility. Circulation 1997; 95: 745-752.
3. De Hert SG, Gillebert TC, ten Broecke PW, et al. Contraction-relaxation coupling and impaired left ventricular performance in coronary surgery patients. Anesthesiology 1999; 90: 748-757.
4. De Hert SG, Gillebert TC, ten Broecke PW, et al. Length-dependent regulation of left ventricular function in coronary surgery patients. Anesthesiology 1999; 91: 379-387.
© 2004 European Academy of Anaesthesiology