Biomedical subjects

H I van der Spoel

Publications and source records attributed to H I van der Spoel.

4 recordsLinked to original sources

PubMed1996

The influence of weight on stroke volume determination by means of impedance cardiography in cardiac surgery patients.

OBJECTIVES: Obesity is thought to be one of the conditions in which the impedance cardiographic method is less reliable for estimating stroke volume (SV). This led to the introduction of a weight correction factor, sigma, into the equation according to Sramek and Bernstein. However, no scientific evidence has been published to support the use of this factor. The objectives of the present study are to evaluate the influence of body weight on the accuracy of impedance cardiography and to validate Bernstein's weight correction factor by comparison with thermodilution in patients after coronary bypass surgery. DESIGN: Prospective clinical study. SETTING: A surgical intensive care unit in a university hospital. PATIENTS: 37 consecutive patients 24-36 h after coronary bypass surgery, sub-divided into a normal-weight group (n = 24), patients whose weight deviated less than 15% from their ideal weight, and an obese group (n = 13), patients whose weight deviated more than 15% from their ideal weight. MEASUREMENTS: Kubicek's impedance cardiographic method and Sramek and Bernstein's method to assess SV are applied and compared to thermodilution. In order to study the validity of sigma, the results are compared between 24 patients with normal weight and 13 obese patients. RESULTS: A significant correlation between miscalculation of SV by impedance cardiography and the degree of obesity for Sramek and Bernstein's method is found when sigma is not included in the equation (r = -0.55, p < 0.05). This relation, however, remained significant when sigma was included in the equation (r = -0.40, p < 0.05). Kubicek's method shows no significant correlation for this relation (r = -0.30). Besides this, Sramek and Bernstein's method underestimates SV significantly in the obese group, independent of the use of sigma in the equation. These results are explained as being intrinsic to the equation, according to Sramek and Bernstein. In the whole group the impedance-derived SV did not significantly differ from SV as measured by means of thermodilution, independent of the method used to calculate SV. However, a considerably better correlation and agreement (mean difference +/- 2 standard deviations is found when Kubicek's method is applied (r = 0.90, 0.5 +/- 17.1 ml vs 0.64, -4.9 +/- 31.8 ml for Sramek and Bernstein's method). CONCLUSIONS: Weight significantly influences Sramek and Bernstein's method of impedance cardiography, whereas Kubicek's method is not biased by this factor.

Body Weight↗

PubMed1996

Cardiopulmonary bypass with modified fluid gelatin and heparin-coated circuits.

We have assessed the efficacy of cardiopulmonary bypass (CPB) using normal colloid oncotic pressure (COP) in a randomized, controlled study of 20 patients undergoing elective coronary artery surgery using heparin-coated circuits. For CPB, we used either crystalloid priming 1650 ml (n = 10) or colloid priming 1650 ml (2.4% modified fluid gelatin, n = 10). While COP did not change during bypass in the colloid group, a decline was observed in the crystalloid group (P = 0.005). By the end of bypass, the decrease in COP compared with baseline (delta COP) was 8.5 (S.D. 1.1) mm Hg in the crystalloid group compared with 1.5 (2.1) mm Hg in the colloid group (P = 0.0001). delta COP correlated positively with fluid balance during bypass (r2 = 0.41, P = 0.002). Similar increments in complement factors C3b/c and C4b/c, tumour necrosis factor-alpha and neutrophil elastase, but not endotoxins, were found in both groups as indicators of a systemic inflammatory response. A clinical performance score composed of fluid balance, postoperative duration of intubation and the difference between rectal temperature and skin temperature was more favourable in patients treated with colloid priming (P = 0.03). Median postoperative hospital stay was 7 (range 5-16) days in the crystalloid group compared with 5 (4-8) days in the colloid group (P = 0.016). Regression analysis indicated that CPB time, fluid balance during operation and postoperative PO2/FlO2 ratio were independent factors that predicted postoperative hospital stay. From these preliminary results we conclude that in the absence of endotoxaemia, use of a normal COP during CPB with modified fluid gelatin in heparin-coated circuits resulted in an improved postoperative course an a reduction in hospital stay.

Aged↗

PubMed1996

Standardization of non-invasive impedance cardiography for assessment of stroke volume: comparison with thermodilution.

Since its introduction by Kubicek and colleagues, impedance cardiography has been suggested as a non-invasive, simple, safe and cost-effective method of measuring stroke volume. Several controversial reports on its validity have been published. Pitfalls of this method included the nature of the electrode system and the validity of the equations. Therefore, the purpose of this study was to compare two different spot electrode arrays and the two most frequently used stroke volume equations with each other and with thermodilution. In 37 patients, 24-36 h after cardiac surgery, we performed simultaneous measurements of stroke volume with impedance cardiography (SVIC) and with thermodilution (SVTD). SVIC was obtained using the lateral spot (LS) electrode array, according to Bernstein, and a newly proposed modified semi-circular (MSC) spot electrode array. The equations of Kubicek and Sramek-Bernstein were used to calculate SVIC. The Sramek-Bernstein equation was valid only when the LS array was used; the Kubicek equation determined SVTD correctly only when the MSC array was used. However, a considerably better correlation and agreement (mean difference (2 SD)) was found between SVIC and SVTD for the latter (r = 0.90, 0.5 (17.1) ml vs r = 0.64, -4.9 (31.8) ml for the Sramek-Bernstein equation). We conclude that the most valid measurement of stroke volume using impedance cardiography was obtained when the MSC array was used together with Kubicek's equation.

Adult↗

PubMed1995

Reduced complement activation and improved postoperative performance after cardiopulmonary bypass with heparin-coated circuits.

A randomized controlled trial that involved 30 patients undergoing elective coronary artery bypass grafting was done to determine the effect of heparin-coated circuits and full heparinization on complement activation, neutrophil-mediated inflammatory response, and postoperative clinical recovery. Peak concentrations of terminal complement complex were 38% lower (p = 0.004) in 15 patients treated with heparin-coated circuits (median 775 micrograms/L, interquartile range 600 to 996) compared with those in 15 patients treated with uncoated circuits (median 1249 micrograms/L, interquartile range 988 to 1443). Although no significant intergroup differences in concentrations of polymorphonuclear neutrophil elastase were found, a positive correlation (rs = 0.74, p < 0.0007) was calculated between peak concentrations of terminal complement complex and polymorphonuclear neutrophil elastase. Differences in patient recovery were analyzed with use of a score composed of fluid balance, postoperative intubation time, and the difference between rectal temperature and skin temperature. The score was significantly lower in patients treated with heparin-coated circuits (p = 0.03), whereas its components showed no intergroup significance. We conclude that the use of heparin-coated circuits with full systemic heparinization results in improved biocompatibility, as assessed by complement activation, and leads to an improved postoperative recovery of the patient.

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