Clinical role of blood heparin level monitoring during open heart surgery.

Protamine has been used for neutralizing heparin and its dosage is decided by the initial fixed dose of heparin. Adequate protamine neutralization is very important to reduce complications. To attenuate excess reactions, in particular, whole blood heparin concentration during and after cardiopulmonary bypass was measured using Hepcon, and the efficacy of optimal protamine dose in open heart surgery was evaluated. Twenty patients were randomly divided into two comparable groups, P and C. In the C group, heparin was neutralized with an initial fixed dose of protamine, 1.67 mg protamine per milligram total heparin (n = 8). In the P group, protamine dose was determined for residual heparin concentration (n = 12). In the P group, blood heparin concentrations at 60 minutes after the establishment of cardiopulmonary bypass, just after cardiopulmonary bypass and first protamine administration were 2.35 +/- 0.14, 2.31 +/- 0.17 and 0.13 +/- 0.08 U/ml, respectively. Concentrations reached zero with the second protamine administration. The requirement of transfusion (659 +/- 224 vs. 1559 +/- 323 ml, p = 0.0314), pulmonary vascular resistance index just after the protamine administration (190 +/- 22 vs. 286 +/- 18 dyne.s.cm-5.m2, p = 0.0137) and the IL-8 levels (just after protamine: 26.9 +/- 5.1 vs. 43.5 +/- 5.9 pg/ml, p = 0.0499, 12 hours after cardiopulmonary bypass: 37.1 +/- 12.1 vs. 86.8 +/- 20.0, p = 0.0435) in the P group were significantly lower than those in the C group. These data suggested that heparin level monitoring in whole blood may be useful to determine the optimal dose of protamine resulting in the decrease of a requirement of blood components in open heart surgery and attenuating in transient pulmonary hypertension and excess protamine-induced inflammatory reactions.     

心内直视手术中去白细胞血灌注液对心肌的保护作用

目的 评价心内直视手术期间使用滤除白细胞的血液灌注液对心肌的保护效果。方法 ３０例择期行心脏瓣膜替换术的患者，ＡＳＡⅡ～Ⅳ级，均采用芬太尼－安氟醚复合麻醉，以４℃高钾晶体液灌注停跳，据第二次灌注液成份不同随机分为３组，每组１０例；晶体 组（ＣＳ）、全血组（ＷＢ）和去白细胞血（ＬＤ）组，于肝素化前，ＣＰＢ开始５ｍｉｎ，主动脉开放前５ｍｉｎ，开放后３０ｍｉｎ、１ｈ、２ｈ、２４ｈ采取外周动脉血测定ＣＫ－ＭＢ、ＩＬ－８、ＴＮＦα浓度，于主动脉阻断前、开放前、开放后１５ｍｉｎ取右心房心肌标本，测定心肌含水量和心肌组织Ｃａ＾２＋含量和心肌组织Ｃａ＾２＋含量，观察心肌组织超微结构改变，对心肌线粒体变化进行半定量评价。结果 开放主动脉后，每组ＣＫ－ＭＢ、ＩＬ－８水平较开放前明显升高，开放后２ｈ升高更明显（Ｐ〈０．０５），但ＬＤ     

Monitored protamine infusion for heparin neutralisation in open heart surgery

Determining the proper dosage of protamine for heparin reversal in open-heart surgery is often arbitrary and both under-and overdosing are possible. We describe here a method of protamine administration that was studied in 50 patients undergoing open heart surgery. Protamine was given as a slow, controlled infusion guided by repeated activated clotting time measurements till the earliest return of these values to base-line levels. Using this technique, 39 (78%) patients had an adequate heparin reversal at the end of surgery, at doses of protamine less than those used conventionally. There was no unusual increase in 24-hour chest tube drainage in these patients. The method appears to be a safe and effective alternative to traditional protocols of heparin neutralisation.     

Myocardial metabolic monitoring with the microdialysis technique during and after open heart surgery

BACKGROUND: Post-operative ischemia after coronary artery bypass grafting (CABG) is well described but effective intervention requires immediate diagnosis. One possible way of increasing efficacy of peri-operative myocardial monitoring is using the microdialysis technique. METHODS: In 30 patients undergoing routine CABG, a microdialysis catheter was inserted in the left heart in an area of abnormal ventricular contraction. A second catheter was placed in normal tissue of the right ventricle. Microdialysis measurements were performed at time intervals before, during and 24 h after cardiopulmonary bypass (CPB) and retrospectively compared with standard clinical monitoring and clinical course. RESULTS: During CPB, both ventricles showed signs of poor tissue oxygenation. Glycerol was significantly higher in the left myocardium (146 +/- 67 vs. 72 +/- 36 micromol/l) and the glucose/lactate ratio (GLR), as a marker of nutritional disorder of the right ventricle (41 +/- 15% vs. 67 +/- 17%, P < 0.05), had significantly better values at this time point. Myocardial lactate concentrations were significantly higher in the dyskinetic segments (2.82 +/- 0.81 vs. 1.5 +/- 0.81 microM). During this period, no abnormal clinical standard monitoring results were observed. Post-operative significantly increased lactate/pyruvate ratios of three patients were clinically associated with peri-operative myocardial infarction (108 +/- 67 vs. 38 +/- 9, P < 0.05). The lactate/pyruvate ratio started rising before any other standard monitoring tools showed abnormal values. CONCLUSIONS: Peri-operative microdialytic measurements of parameters related to ischemia can be safely performed in a clinical setting, resulting in faster and more reliable detection of ongoing or new ischemia.     

Perioperative management of blood glucose during open heart surgery in infants and children

The perioperative management of blood glucose has been controversial since clinical associations between hyperglycemia and adverse outcomes were first reported more than two decades ago. Despite some early evidence supporting a causal relationship between hyperglycemia and adverse outcomes, prospective trials of tight glycemic control have been inconclusive, except in selected populations, like adult diabetics. These trials have consistently reported dramatic increases in the incidence and severity of hypoglycemia, which may also have associated adverse outcomes. Bedside glucose monitors typically used to manage glucose have increasingly been found to introduce systematic inaccuracies. Relevant studies of infants and children undergoing cardiac surgery are considerably fewer in number, requiring clinicians to extrapolate from other clinical conditions and patient populations.     

External DC defibrillation during open heart surgery

A technique of external DC defibrillation during open heart surgery is described. It has proved of value in second operations and has been consistently successful except in some patients with aortic valve disease and massive left ventricles.     

On-line electrical impedance measurement for monitoring blood viscosity during on-pump heart surgery

BACKGROUND: The viscosity of blood (eta) as well as its electrical impedance at 20 kHz at high shear rate depends on hematocrit, temperature, concentration of macromolecules and red cell deformability. The aim of our study was to investigate the relation between viscosity and electrical impedance in a heart-lung machine-like set-up, because during on-pump heart surgery considerable viscosity changes occur. METHODS: Blood of 10 healthy volunteers was examined under temperature variation between 18.5 and 37 degrees C at four different levels of hemodilution. Blood viscosity was examined with a golden-standard technique, i.e. a Contraves LS 30 Couette viscometer, and the results were compared with measurements of the electrical resistivity (R) at 20 kHz by a specially designed device in series with the tubing system of a heart-lung machine. All measurements were performed at a shear rate of 87 s(-1). RESULTS: Using stepwise multiparameter regression analysis (SPSS) a highly significant correlation was found (r(2) = 0.882) between viscosity (eta) and resistivity (R). Adding the variables sodium ([Na(+)]) and fibrinogen ([Fibr]) concentration the coefficient of correlation further improved to r(2) = 0.928 and the relation became: eta = -0.6844 + 0.038 R + 0.038 [Na(+)] + 0.514 [Fibr]. All coefficients showed a statistical significance of p < 0. 001. CONCLUSIONS: Electrical impedance measurement is feasible in a heart-lung machine-like set-up and allows accurate continuous on-line estimation of blood viscosity; it may offer an adequate way to record and control viscosity changes during on-pump heart surgery.     

Markers for endothelial activation during open heart surgery

BACKGROUND: Reliable markers for endothelial activation are needed when studying biocompatibility of cardiopulmonary bypass. METHODS: Blood samples from 21 patients undergoing combined valve and coronary artery bypass surgery were collected before anesthesia (T1), after re-transfusion of blood from the heart-lung machine (T2), and on the first postoperative morning (T3). Concentrations of soluble markers were determined using sandwich enzyme-linked immunoadsorbent assay for sICAM-1, sVCAM-1, and sE-selectin. The sera were also used to stimulate human umbilical vein endothelial cells (HUVEC) in culture for 6 hours, in which activation was measured using cell enzyme immunoassay for mICAM-1 and mVCAM-1. RESULTS: The concentrations of sICAM-1 and sVCAM-1 increased during both measurement intervals (p < 0.05). The sICAM-1 T1 was 311.0 ng/mL (range, 271.0 to 350.7 ng/mL); the sICAM-1 T2 was 341.6 ng/mL (range, 322.0 to 422.0 ng/mL), and the sICAM-1 T3 was 400.2 ng/mL (range, 348.0 to 556.4 ng/mL; the sVCAM-1 T1 was 607.5 ng/mL (range, 497.8 to 813.8 ng/mL), the sVCAM-1 T2 was 755.3 ng/mL (range, 660.6 to 834.4 ng/mL), and the sVCAM-1 T3 was 1149.0 ng/mL (946.0 to 1406.0 ng/mL); whereas the sE-selectin increased from T1 to T3 (p < 0.01). Both the mICAM-1 (p < 0.002) and the mVCAM-1 (p < 0.005) increased on the human umbilical vein endothelial cells in culture after stimulation with the patient sera. The amounts of soluble markers in vivo were not correlated with the degree of endothelial activation in vitro, but were correlated with various operative variables including age, medication, and time of aortic cross-clamping. CONCLUSIONS: Endothelial cells were activated during cardiopulmonary bypass. The soluble adhesion molecules sICAM-1, sVCAM-1, and sE-selectin displayed different kinetics, rendering it difficult to determine a simple expression for the degree of endothelial cell activation. Clinically, sVCAM-1 seemed to be the best-suited marker for endothelial cell activation, because it was only associated with aortic cross-clamping and heparin and protamine doses, and it also showed the largest numerical changes.