Useful ectopics
Editor—The use of trans-oesophageal Doppler cardiac output monitoring (Cardio Q, Deltex Medical, Chichester, UK) for perioperative fluid optimization is well documented. Increasingly the benefit of goal-directed perioperative intra-vascular filling on postoperative morbidity is being realized.1–3A simple algorithm using boluses of colloid i.v. fluid based on the Starling principle has been followed and has led to more rapid recovery after major surgery, a reduction in postoperative length of hospital stay and 5.3:1 reduction in the incidence of postoperative gut complications compared with central venous pressure targeted controls.1
The Deltex Cardio Q displays a velocity–time curve for every heartbeat. This gives the user the ability to see the data displayed on which the machine has calculated stroke volume and cardiac output. In following the simple stroke algorithm (Fig. 1), occasionally increases in systemic vascular resistance can affect the stroke volume making it slightly more difficult to interpret the filling requirements. However, if a premature atrial ectopic beat occurs, followed by a compensatory pause, this can provide useful additional information. In Figure 2 for example, the premature beat is smaller than the ‘normal’ beat because of reduced filling time. The beat following the compensatory pause has had increased diastolic filling time. If this later beat is larger (greater area under the curve) than the ‘normal’ beats, it shows there is unused filling capacity within the heart and more colloid can be given safely. However, if this beat is of similar size or indeed smaller than the normal beat, then it is likely that the heart is operating at the top of the Starling curve already—consequently further filling would not be advised. This phenomenon can therefore be used to support the use of the oesophageal Doppler fluid algorithm.
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Worthing, UK, BN11 2DH
*E-mail: howard.wakeling{at}wash.nhs.uk
References
1 Wakeling HG, McFall MR, Jenkins CS, et al. Intraoperative oesophageal Doppler guided fluid management shortens postoperative hospital stay after major bowel surgery. Br J Anaesth 2005; 95:634–42
2 Mythen G and Webb A. Perioperative plasma volume expansion reduces the incidence of gut mucosal hypoperfusion during cardiac surgery. Arch Surg 1995; 130:423–9[Abstract]
3 Sinclair S, James S, Singer M. Intraoperative intravascular volume optimisation and length of hospital stay after repair of proximal femoral fracture: randomised control trial. Br Med J 1999; 315:909–12
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