The effect of priming techniques of ultrafiltrators on blood rheology: an in vitro evaluation.

The increased interest of using ultrafiltration during cardiopulmonary bypass ICPB) has mandated a re-evaluation of the hematological effects of this blood conservation process. 'Rinse-free' ultrafiltrators can be primed using either crystalloid or blood prior to use. It is unknown whether one priming technique results in superior results in ultrafiltration quality. An in vitro circuit was designed to evaluate the Sorin/COBE HC1400 (n=6), the Lifestream HC70 (n=6), and the Terumo/Sarns HC11 (n=6). All test conditions were conducted at a blood flow rate of 250 ml/min and a transmembrane pressure of 250 mmHg. Samples were drawn and analyzed at four distinct time points for hematocrit, total protein, plasma free hemoglobin, interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor-alpha (TNFalpha). The HC11 had significantly greater percent increases in hematocrit under the blood priming protocol (29.2+/-7.9) than either the HC1400 (11.0+/-7.8, p<0.03) or the HC70 (11.9+/-7.8, p<0.04). When crystalloid priming was compared to blood priming, the HC1400 and HC70 produced significant percent increases in hematocrit and total protein levels. The HC1400 devices produced significantly less plasma free hemoglobin when primed with crystalloid rather than blood (43.6+/-38.3 vs 21.3+/-5.6, p<0.01). There were no significant differences between devices or priming techniques for IL-6, IL-8 or TNFalpha levels. In conclusion, the efficiency of the ultrafiltrators was elevated when primed with crystalloid before use. Cytokine levels were relatively unchanged with priming techniques, while plasma free hemoglobin levels were reduced with those devices previously primed with crystalloid.

An experimental evaluation of continuous cardiotomy reservoir ultrafiltration.

Ultrafiltration has been suggested as a means to reduce the morbidity associated with blood activation. However, the application of ultrafiltration to the highly activated blood of the cardiotomy suction subcircuit has not been investigated. The purpose of this study was to determine whether cardiotomy reservoir ultrafiltration (CRUF) would be effective in altering cytokine levels. Six swine, undergoing 90 min of cardiopulmonary bypass (CPB), were divided into two groups; one group was assigned to receive CRUF (N = 3), the other was to serve as controls and did not receive ultrafiltration (N = 3). Blood samples were analyzed for hematocrit, plasma-free hemoglobin, total protein, interleukin-8 (IL-8), and tumor necrosis factor alpha (TNF-alpha). Samples were taken pre-bypass, postheparinization, every 30 min during CPB, post-CPB and postprotamine. All data were analyzed using a one-way analysis of variance (ANOVA), with significance accepted at p < .05. There were no significant differences found between treatment and control groups for plasma-free hemoglobin levels (22.4 +/- 22.2 vs. 14.6 +/- 14.4; 40.1 +/- 26.1 vs. 40.0 +/- 19.3). After 90 min of ultrafiltration, there was a significant decrease in TNF-alpha (261.6 +/- 119.6 vs. 71.8 +/- 11.4; p = .02). Although IL-8 levels decreased from throughout the experiment, concentrations did not reach statistical significance. In conclusion, CRUF can be used without increasing cellular destruction, and can decrease certain cytokine levels. Our results suggest that further clinical studies should be undertaken utilizing this technique with a larger sample size.

The effects of continuous blood gas monitoring during cardiopulmonary bypass: a prospective, randomized study--Part I.

The use of continuous in-line blood gas management (CILBGM) is steeped in controversy concerning its potential utility and impact on patient outcomes. The purpose of this study was to determine whether the use of CILBGM results in improved quality of patient care. Fifty-nine patients were enrolled in a Institutional Review Board-approved, prospective, randomized study. An in-line blood gas monitor (CDI 500) was placed into the arterial and venous lines for all patients. Blood gas monitoring in the control group was managed by intermittent sampling (every 20-30 min), while the treatment group was managed with continuous monitoring. There were no differences between groups in preoperative, surgical, anesthetic, or perfusion variables. The accuracy of the in-line monitor was comparable to laboratory analysis for arterial blood gas parameters (N = 160; pH bias = 0.00; PaCO2 bias = -1.1 mmHg; and PaO2 bias = 0.7 mmHg). There was less deviation from target values (pH = 7.40, PaCO2 = 40 mmHg, PaO2 = 150-200 mmHg) when in-line monitoring was used versus intermittent sampling (N = 784; pH deviation = 0.05 +/- 0.03 vs. 0.03 +/- 0.01, p < 0.0001; PaCO2 deviation = 4.0 +/- 2.9 mmHg vs. 2.0 +/- 0.9 mmHg, p < 0.0001; and PaO2 deviation = 22.7 +/- 16.9 mmHg vs. 11.7 +/- 8.3 mmHg, p < 0.0001). In conclusion, the results of part I of this study demonstrate that the use of CILBGM results in more accurate blood gas management during CPB.

The effects of continuous blood gas monitoring during cardiopulmonary bypass: a prospective, randomized study--Part II.

The impact of blood gas management during cardiopulmonary bypass (CPB) on patient care has not been examined and remains controversial. The purpose of this study was to determine whether precise blood gas management during CPB influences patient outcome. Fifty-nine patients were enrolled in an Institutional Review Board-approved, prospective, randomized study. An in-line blood gas monitor (CDI 500) was placed into the arterial and venous lines for all patients. Blood gas monitoring in the control group was managed by intermittent sampling (every 20-30 min), while the treatment group was managed with continuous monitoring. Blood gas control and measured parameters were as follows: pH 7.40 +/- 0.05, PaCO2 40 +/- 5 mmHg, PaO2 200 +/- 50 mmHg. The treatment group had the CDI 500 guide clinical decisions. Compared to the control group, the treatment group consisted of significantly more diabetic (7% vs. 47%, p < or = 0.001), renal failure (3% vs. 13%, p < or = 0.01), and chronic obstructive pulmonary disease patients (7% vs. 20%, p < or = 0.01). Internal thoracic artery utilization was higher in treatment patients than control patients (67% vs. 95%, p < or = 0.02). No other differences existed in demographic, pharmacological, surgical, or anesthetic parameters. In the perioperative period, the control group required antiarrythmic support more frequently than the treatment group (10% vs. 0%, p < or = 0.05). Compared to the control group, the treatment group required antiarrythmic (18% vs. 10%, p < or = 0.05) and cardiac glycoside therapy (11% vs. 0%, p < or = 0.05) less frequently in the postoperative period. Although treatment patients required less intraoperative pacing and cardioversion and spent less time on mechanical ventilation, in the intensive care unit (ICU), and in the hospital than control patients, statistical significance was not achieved. In conclusion, the use of continuous, in-line blood gas monitoring resulted in improvement in a number of postoperative outcome variables, although ICU and hospital stay was not effected.