D. Kling

Preoperative plasmapheresis in patients undergoing cardiac surgery procedures.

Donor plasmapheresis that is carried out weeks before the operation has proven to be of benefit in elective orthopedic patients with regard to reducing homologous blood consumption and preserving coagulation. In this study acute preoperatively performed plasmapheresis (APP) was investigated in cardiac surgery patients. Forty-five patients scheduled for elective aortocoronary bypass surgery were randomly divided into three groups of 15 patients each: 1) removal of platelet-poor plasma (PPP), 2) removal of platelet-rich plasma (PRP), and 3) no plasmapheresis (control group). Plasma volume removed was 10 ml/kg in all APP patients, and plasma was replaced by the same amount of low-molecular weight hydroxyethylstarch solution (6% HES 200/0.5). Various laboratory data were investigated before, during, and after extracorporeal circulation (ECC). Blood loss in control patients was more pronounced than in the two APP groups; two of the control patients needed packed red cells. APP itself did not affect coagulation variables, free hemoglobin, or polymorphonuclear (PMN) elastase. At the end of the operation, 5 h after ECC, and at the first postoperative day the number of platelets was significantly lower in the control group; PRP patients showed the highest values. Fibrinogen and AT-III levels were less compromised in APP patients than in the control group. Global coagulation parameters did not differ between the groups within the whole investigation period. PMN elastase increased significantly during ECC in all groups with the greatest increase in the control group (722%) and the smallest increase in PRP patients (280%), possibly due to the removal of cellular elements in this group.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute preoperative hemodilution in cardiac surgery: Volume replacement with a hypertonic saline-hydroxyethyl starch solution

Preoperative hemodilution (HD) is a recommended practice in cardiac surgery that conserves blood and reduces the complications of homologous blood transfusion. In 45 patients undergoing myocardial revascularization, HD was performed preoperatively. Withdrawn volume (10 mL/kg) was replaced either by a new hypertonic saline (HS) solution prepared in hydroxyethyl starch (HES) (2,400 mOsm/L, HS-HES group, n = 15) or by a standard low molecular weight hydroxyethyl starch solution (6% HES 200/0.5, HES group, n = 15) to maintain baseline PCWP (acute normovolemic hemodilution [ANH]). Fifteen comparable patients without HD served as controls. Significantly less HS-HES (210 +/- 20 mL) than HES 6% (890 +/- 90 mL) was necessary to sustain hemodynamics during HD. Stable cardiocirculatory conditions were obtained even after termination of bypass. Fluid balance during cardiopulmonary bypass as well as in the postoperative period was significantly lower in HS-HES-treated patients. With regard to hemodynamics, CI increased most in the HS-HES group (+36%), whereas systemic vascular resistance was lower in these patients. Right ventricular ejection fraction increased only in HS-HES patients (+15%). However, sodium concentration as well as osmolarity increased after volume replacement with HS-HES, without exceeding normal values. None of the patients suffered from organ failure. Pulmonary gas exchange (PaO2) was less compromised in the HS-HES patients. There were no renal function differences between the groups. In conclusion, HS solution prepared in HES is an attractive alternative for blood substitution in cardiac patients undergoing acute hemodilution for blood conservation.

Influence of acute volume loading on right ventricular function after cardiopulmonary bypass.

The influence of acute volume loading on right ventricular function immediately after extracorporeal circulation (ECC) was investigated in 25 patients undergoing elective aortocoronary bypass grafting. In addition to commonly monitored hemodynamic variables, right ventricular (RV) ejection fraction (EF) was measured by thermodilution technique using a new fast-response thermodilution catheter. In eight patients with concomitant severe stenosis (greater than 89%) of the right coronary artery (RCA), volume loading was followed by a decreased RVEF and cardiac output. In contrast, RVEF in the 17 patients without diseased RCA increased significantly, with an increase in cardiac output. Duration of aortic cross-clamping (i.e., ischemia) was more pronounced in the group with decreased RVEF due to RCA grafting. Increased end-diastolic volume and decreased RV contractility index indicated that patients with myocardial ischemia during cardiac surgery procedures sometimes were unable to make the adaptations required. We conclude that cardiocirculatory dysfunction associated with ECC may be caused by depressed RV function. Acute volume loading in this situation may lead to further deterioration of myocardial function due to RV failure, a condition which cannot be diagnosed readily at the bedside with the usual monitoring techniques.

Volume therapy with hypertonic saline hydroxyethyl starch solution in cardiac surgery

The ideal solution for volume therapy remains controversial. In cardiac surgery, haemodynamic efficacy as well as the influence of extracorporeal oxygenation are of major interest when administering volume. The present study examines the effects of a new hypertonic saline hydroxyethyl starch solution in comparison to a 6% hydroxyethyl starch solution on haemodynamics and laboratory variables. Patients scheduled for elective aortocoronary bypass grafting received hypertonic saline hydroxyethyl starch (n = 10) or hydroxyethyl starch (n = 10) after induction of anaesthesia in order to double baseline pulmonary capillary wedge pressure. Ten patients without volume therapy served as a control group. Significantly less hypertonic solution than standard solution was effective in doubling pulmonary capillary wedge pressure. Fluid requirements in the patients who received the hypertonic solution were significantly less during, as well as after, cardiopulmonary bypass in comparison to those in the other groups. Cardiac index increased most in the patients who received the hypertonic solution (+ 34.8%), as did right ventricular end‐diastolic volume. Patients in that group showed the highest decrease in total systemic resistance (‐ 29.8%), whereas arterial pressure and right ventricular ejection fraction remained almost unchanged in all groups. No negative alteration in coagulation or organ function was demonstrated within the investigation period. It can be concluded that hypertonic saline hydroxyethyl starch solution seems to be a valuable alternative to conventional volume therapy in cardiac surgery.

Revascularization of the right coronary artery: Influence thermodilution right ventricular ejection fraction

This study was designed in order to evaluate the influence of right coronary artery (RCA) disease and its revascularization on right heart performance monitored by measuring thermodilution right ventricular ejection fraction (RVEF). Forty patients undergoing elective aortocoronary bypass surgery were divided into two groups: group 1, with RCA revascularization, n=20; and group 2, without RCA disease or revascularization, n=20. RVEF was measured using a pulmonary arterial catheter mounted with a fast-response thermistor and a bedside microprocessor ejection fraction computer. The major finding of the study was that myocardial revascularization with extracorporeal circulation was followed by a decrease in RVEF which was significantly more pronounced in group 1 (-13.1%) in comparison to group 2 (-5.0%). RVEF gradually increased after bypass, but did not reach baseline values. By the first postoperative day, RVEF had reached baseline values again in group 1 and had increased beyond baseline values in group 2. Traditionally measured hemodynamic parameters could not be correlated with the course of RVEF, except for cardiac index. The present study further suggests that right-sided events may have clinical effects on left-sided function. Inadequate protection of the right heart, especially in patients with RCA stenosis, may result in depression of right ventricular myocardial performance, which can be monitored serially by measuring RVEF.

Influence of acute normovolemic hemodilution on extravascular lung water in cardiac surgery

Preoperative hemodilution (HD) is an established blood-saving method. With HD, however, a concomitant increase in extracellular and interstitial water has been reported. This randomized study was undertaken to compare the effects of acute normovolemic HD (10 ml/kg; n = 15) using hydroxyethyl starch solution (HES) on extravascular lung water (EVLW) with those of an untreated control group (n = 15) of cardiac surgery patients submitted to extracorporeal circulation (ECC). A thermal-dye technique was used to measure EVLW. There was no significant change in EVLW due to preoperative HD (5.55 +/- 0.51 vs. 5.71 +/- 0.59 ml/kg). After ECC, a transient increase in both groups could be demonstrated because of a possible change in pulmonary capillary permeability (maximal increase in the HD group: +1.30 ml/kg and in the nonHD group: +1.02 ml/kg). Five hours after ECC, no differences could be seen between the groups. Pulmonary gas exchange was not significantly affected (PaO2 in the HD group: -20 torr). Hemodynamic and laboratory variables indicated the typical changes during HD (cardiac index increases while albumin concentration decreases); circulatory stability was maintained during the entire study. We conclude that preoperative normovolemic HD did not increase lung water content significantly nor compromise pulmonary function even in cardiac surgery patients. Although ECC provides an additional HD (crystalloid priming of the heart-lung bypass machine) and possibly damage of capillary integrity, the two groups did not differ.

Spectral analysis of the EEG during hypothermic cardiopulmonary bypass

In 39 patients undergoing aorto‐coronary‐bypass grafting, spectral analysis of the EEG (compressed spectral array: CSA) and calculation of spectral edge frequency (SEF) were performed. The effects of different temperatures and of perfusion pressure (PP) were analyzed. Predictable patterns were observed. During cooling on cardiopulmonary bypass (CPB). linear regression analysis revealed a close correlation between SEF and tympanic membrane (Tty) or nasopharyngeal temperature (Tnp). During rewarming, a nonlincar correlation between SEF and Tty or Tnp was found. Rectal temperature as well as blood temperature in the arterial or venous line of the oxygenator seemed to be less useful. The independence of SEF and PP was demonstrated during the whole procedure. At the onset of CPB, after correction of the aortic clamp for performance of the aortic anastomosis and after removal of the aortic clamp, bilateral EEG slowing of varying duration occurred in 20 patients. Comparison of mean SEF before and after CPB revealed a difference of about 5 Hz. In no patient were major neurological abnormalities observed postoperatively.

Enoximone treatment of impaired myocardial function during cardiac surgery: combined effects with epinephrine

Enoximone belongs to a new class of noncatecholamine-positive inotropes, which selectively inhibit phosphodiesterase type III and increase cyclic AMP (cAMP). This study was performed in 30 coronary artery surgery patients with impaired myocardial function (ejection fraction [EF] less than 50%). The studys two purposes were to investigate the hemodynamic effects of enoximone, 0.5 mg/kg, administered following induction of anesthesia (phase I), and to assess whether enoximone can potentiate the actions of sympathomimetic agents during weaning from cardiopulmonary bypass (CPB) (phase II). Starting with already reduced hemodynamics, induction of anesthesia led to a further deterioration of blood pressure and cardiac output (CO). Administration of enoximone produced a significant increase in cardiac index (CI) (+47%), whereas pulmonary capillary wedge pressure (PCWP) (-37%), pulmonary artery pressure (PAP) (-17%), and systemic vascular resistance (SVR) (-17%) were significantly reduced. Heart rate (HR) was not increased, and no dysrhythmias occurred during the investigation. The hemodynamic effects were maintained for 30 minutes until the start of the operation. In phase II, where weaning from CPB was not possible without pharmacological support, either enoximone (0.5 mg/kg) + epinephrine (0.1 micrograms/kg/min) or only epinephrine (same dosage) was randomly selected. Weaning was successful in both groups, but the combined therapy produced a larger increase in cl and a more pronounced decrease of the elevated filling pressure (PCWP). PAP was not changed in the combined therapy group, but increased in the patients receiving epinephrine alone. It is concluded that enoximone has beneficial hemodynamic effects in the perioperative period, and that potentiation of the effects of epinephrine in severe heart failure may be one of the drugs most useful features.

Acute plasmapheresis during cardiac surgery: volume replacement by crystalloids versus colloids.

Acute plasmapheresis (APP) is an additional tool for blood conservation during cardiac surgery. In a randomized study of 60 aortocoronary bypass patients undergoing APP, the influence of replacement of the withdrawn autologous plasma (10 mL/kg) by either colloids (low molecular weight hydroxyethyl starch solution [6% HES 200/0.5]) or crystalloids (Ringers solution) was investigated. APP was performed by means of a centrifugation technique producing platelet-poor plasma. During and after cardiopulmonary bypass (CPB), either a cell saver (CS) or a hemofiltration (HF) device was also used for blood concentration. Almost three times as much crystalloid as HES solution was necessary for replacement of autologous plasma. Fluid balance during CPB was significantly more positive in the crystalloid patients, particularly when a CS was used. Blood loss was highest in the crystalloid patients in whom a CS was used in addition to APP, and these were the only patients who needed packed red cells. The platelet count, AT-III and fibrinogen plasma concentrations, colloid osmotic pressure, albumin, and total protein were significantly less compromised in the patients with colloid volume replacement. These parameters were closest to control values in patients receiving colloid replacement and HF. It is concluded that colloid is preferred for replacement of autologous plasma withdrawn by APP, and HF is superior to the CS when the combined technique for blood conservation is used.

RETRACTED: Acute preoperative plasmapheresis and established blood conservation techniques

Plasmapheresis performed weeks before an operation producing autologous plasma has proved to be of benefit in elective operations. First experiences in acute plasmapheresis, which is performed immediately before the operation, have been reported recently. When acute plasmapheresis is used in cardiac operations, however, it must be viewed in connection with other techniques for reducing blood consumption such as the Cell Saver (CS) and ultrafiltration devices. In 60 patients undergoing elective aortocoronary bypass grafting, acute plasmapheresis was performed, producing either platelet-poor plasma or platelet-rich plasma, in combination with either the Cell Saver or hemofiltration. Fluid balance during cardiopulmonary bypass was significantly lower in the hemofiltration patients. Postoperatively, none of these patients received donor blood, whereas 4 patients of the Cell-Saver groups needed packed red blood cells. AT-III, fibrinogen, the number of platelets, albumin, total protein, and colloid osmotic pressure were less compromised when hemofiltration was used in combination with acute plasmapheresis in contrast to combination with the Cell-Saver technique. Plasma hemoglobin was without differences during the investigation period, and polymorphonuclear elastase was less increased when platelet-rich plasma was produced preoperatively. On the first postoperative day, most of the differences between the groups had already disappeared. We conclude that when acute plasmapheresis is used in cardiac operations, discarding of plasma by the Cell Saver should be avoided and ultrafiltration devices should replace centrifugation techniques for blood conservation.