An Evaluation of Three Methods for Determining Colloid Osmotic Pressure

Plasma colloid osmotic pressure (COP) is an important determinant in edema formation. Three methods for assessing the COP were evaluated. Direct measurement of COP using the 4420 Wescor Colloid Osmometer was compared to the estimation of COP from both serum total protein and total serum solids (TSS) determinations. Blood samples from twenty adult patients (mean age = 64 years) undergoing cardiopulmonary bypass surgery were collected for COP assessment. Sample collection was performed prior to heparinization/hemodilution, during hypothermic bypass and at the conclusion of bypass following protamine administration. The results obtained from each method were analyzed by a two-way analysis of variance. The Bonferroni technique was used for comparison of sample means when the difference was significant (p<0.05). Correlations were reported by linear regression analysis. A statistically significant difference (p<0.01) was found between the three methods. A regression equation for the estimation of COP from total serum solids is offered: COP = (3.02 * TSS) + 0.65. Prospective clinical testing between the direct COP measurement and the estimation of COP from TSS using the equation (n=38) revealed a significant correlation (R2 = .932) and no significant difference between the two (p > 0.05)

Hemochron vs. Hemotec Kaolin ACT Comparison with Aprotinin Use in Congenital Heart Surgery

Between July 1994 and January 1995, ten patients underwent reoperative cardiac surgery with cardiopulmonary bypass for correction of various congenital anomalies. The patients' ages ranged from 0.17 to 34 years. Aprotinin was used according to surgeon protocol (200 mg/m2 body surface area initial loading dose and in pump prime, and 50 mg/m2 hourly infusion). The purpose of this study was to compare the simultaneous ACT values obtained from the Hemotec cartridge and the Hemochron kaolin tube. A 3 ml blood sample was drawn and duplicate ACTs run at four time periods during the procedure: 2 ml in a prewarmed kaolin Hemochron tube and 0.4 ml in each well of a pre-warmed Hemotec cartridge. Information recorded at each time period included: event [pre-CPB, onCPB hypothermia, on-CPB rewarming, post-CPB], temperature, and ACT values from each machine. A total of 74 paired samples were analyzed. Two-way ANOV A was used to compare the values. Multiple comparison tests using the Bonferonni method were performed to maintain the Type I error rate at 0.05. Regression, correlation, and residual analyses were performed. Cohen's kappa statistic was used to assess the degree of agreement between the two devices. There was a statistically significant difference between the ACT values obtained between the two devices (p<.01); however, the correlation between the values was high and significant (r=0.841, p<.01). The Hemotec was an average of 86 seconds lower than the Hemochron. The kappa statistic was 0.688, which indicates good agreement. The differences between these two devices have been previously reported using the celite Hemochron tubes, and it appears that there is still a difference when both tubes contain kaolin. Differences in the method of clot detection, differences in sample volume, and differences in the adsorption of aprotinin may explain the differences observed in this study. The Hemochron kaolin ACT is an acceptable alternative to the Hemotec ACT for monitoring heparinization when aprotinin is in use in congenital heart surgery

Information and Communication Technologies in Hands-On Science: Emerging Trends Across Three Nations

This article introduces a framework for classifying information and communication technologies (ICT) in hands-on science activ-ities in K-12 education. Exemplary projects from the USA and the Netherlands demonstrate the potential of the use of ICT. Ex-amples from Japan illustrate how developments in hands-on sci-ence in the western world have influenced Japan's educational policy at the national level, leading toward systematically planned initiatives in that nation. The impact of hands-on sci-ence on student learning is also discussed. The article concludes with a discussion of possible technological, logistical, and peda-gogical barriers to wide-scale implementation

Clinical Evaluation of a New In-Line Continuous Blood Gas Monitor

Two methodologies for obtaining accurate blood gas and electrolyte values during cardiopulmonary bypass (CPB) are traditional laboratory analyzers, which use an electrochemical technology, and continuous in-line monitoring systems, which use a fluorometric and/or spectrophotometric technology. The purpose of the present study was to evaluate the accuracy of a new continuous in-line monitor, the 3M™ CDI™ Blood Parameter Monitoring System 500, which provides continuous in-line measurements of pH, PCO2, PO2, potassium (K+), oxygen saturation, hematocrit, hemoglobin, and temperature, during partial or complete CPB. Study parameters included arterial pH, PCO2, PO2 , and K+ values. Overall performance was analyzed by calculating the mean difference (expressed as the bias) between the CDI system 500 and the laboratory analyzer for each parameter. The accuracy of the arterial pH, PCO2, and K+ values provided by the CDI system 500 was then evaluated using target values established in the acceptable performance standards for laboratory analyzers from the Clinical Laboratory Improvement Act of 1988 (CLIA '88). The accuracy of the PO2 value provided by the CDI system 500 was evaluated using a target value of ± 10% of the reference, or laboratory analyzer, value. A prospective multi-center trial was conducted following Institutional Review Board approval. A total of 75 cases was included in the analyses, with over 200 data points from 4 clinicallocations. Results for pH, PCO2 , and K+ were within the target values established by CLIA '88. pH bias was 0.00 ± 0.02 pH units. PCO2 bias was −0.3 ± 3.3 mm Hg. K+ bias was approximately + 0.12 ± 0.31 mmole/l. Results for PO2 were within 10% of the reference value. PO2 bias was 7.5 ± 13.8 mm Hg. The results of this clinical trial show that the CDI System 500 continuous in-line monitoring system provides values that meet the accuracy standards for laboratory analyzers for arterial pH, PCO2, PO2, and K+

Plasmapheresis Techniques During Cardiac Surgery

Plasmapheresis is an aggressive autologous blood conservation method utilized in cardiac surgery to reduce patient exposure to homologous blood transfusion. Presently the three perioperative techniques which have been used clinically incorporate varying methodology in producing platelet rich plasma (PRP). However, no prospective randomized study has been made to concurrently examine the benefits of individual devices. Fifty-two consenting adult cardiac patients who met selection criteria were randomly assigned to one of three plasmapheresis devices: Plasma Saver (PS), Cell Saver (CS), and Autotrans 1000 (AT 1000). Following induction of anesthesia, 20% of each patient's estimated plasma volume was removed, stored and then reinfused following the reversal of heparin with protamine. One hundred and twenty-two parameters were measured for each patient. These included anthropomorphic, operative, cardiopulmonary bypass, and postoperative follow-up parameters. Indices of hemostasis were measured which included coagulation screens and thrombelastographic data. There were no differences between groups in all preoperative parameters including the volume of PRP removed. Fibrinogen levels in the PRP were 213.9 +/- 63, 219.4+/-73, and 188.9+/- 69mg/dl in groups PS,CS, and AT 1000 (p=NS), while platelet counts were 178.4 +/- 73, 121.6 +/- 85, and 210.6 +/- 77 109/L, respectively (p<.05 CS vs. AT). There were no differences in chest tube drainage, time on ventilator, or length of ICU stay between groups. However, patients in PS group had significantly lower discharge platelet counts than groups CS and AT 1000. Total homologous blood exposure rate (donor blood exposure per patient) was 8.2 units in group PS, 4.5 in CS, and 5.4 in AT 1000, (p=NS). The currently available techniques for perioperative PRP production differ in both methodology and platelet yield, although the difference did not result in significantly different patient postoperative outcome indices