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Continuous blood density measurements and volume changes during extracorporeal circulation in patients undergoing
1Department of Heart Surgery, University Surgery Center, Graz, Austria.
Insights
This study measured fluid shifts during extracorporeal circulation (ECC) using blood density. Catecholamine administration significantly increased transcapillary volume loss in patients undergoing heart-lung bypass.
Area of Science:
- Cardiovascular Surgery
- Physiology
- Medical Engineering
Background:
- Extracorporeal circulation (ECC) involves complex fluid shifts.
- Accurate monitoring of blood volume and transcapillary fluid dynamics is crucial during cardiac surgery.
Purpose of the Study:
- To examine blood volume changes and transcapillary fluid shifts during ECC.
- To evaluate the utility of continuous blood density measurements for assessing fluid dynamics.
Main Methods:
- Continuous blood density measurements using a mechanical oscillator technique (DPRT).
- Discrete measurements using DMA 55 equipment.
- Dilution method and double density method for calculating volume shifts.
- Study included 16 patients undergoing coronary artery bypass surgery.
Main Results:
- Transcapillary volume loss averaged 870 ml/m2 BSA by dilution and 830 ml/m2 BSA by the double density method.
- The density of transcapillary fluid loss was calculated as 1.0026 g/ml.
- A significant correlation was found between transcapillary volume shift and postoperative catecholamine dosage.
Conclusions:
- Continuous blood density monitoring is a viable method for assessing fluid shifts during ECC.
- Catecholamine administration, particularly dopamine, significantly increases transcapillary fluid loss postoperatively.
- Understanding these fluid shifts is critical for managing patients during and after cardiac surgery.
Abstract:
The changes of blood volume and transcapillary fluid shifts during extracorporeal circulation (ECC) was examined using continuous measurements of blood density by the mechanical oscillator technique. Sixteen patients (1 female, 15 male) with a mean age of 61.4 years (+/- 7.6 years, 47-70 years) undergoing coronary artery bypass surgery were included in this study. The equipment for continuous measurement of the blood density (DPRT by Paar/Austria) was installed at the arterial line of the heart-lung bypass. Higher-precision discrete measurements of some parameters used the DMA 55 equipment produced by the Paar company. Measurements were taken at 37 degrees C. In 11 patients the transcapillary volume loss (difference of total volume between beginning and end of ECC) during heart-lung bypass (mean observation period of 55 min (+/- 16 min, 28-82 min) was found to be 870 ml/m2 body surface area (BSA) (+/- 360 ml, 290-1560 ml/m2) by the dilution method using the priming solution at the beginning and 500 ml lactated Ringer's solution added at the end of the ECC. The calculated volume shift using the "double density method", which takes into account blood density, plasma density, and hematocrit, amounted to 830 ml/m2 BSA (+/- 200 ml, 450-1210 ml/m2). The density of the transcapillary volume loss into the interstitial layer was calculated and found to be 1.0026 g/ml (+/- 0.0017 g/ml, 1.0003-1.0063 g/ml). A significant difference of transcapillary volume shift correlated with the administered catecholamine (dopamine, dobutamine) dosage postoperatively. Without catecholamine this difference was 260 ml/m2 BSA, with 3 microns/kg/min dopamine it rose to > 500 ml/m2 BSA.(ABSTRACT TRUNCATED AT 250 WORDS)