Effect of Carmeda BioActive Surface coating versus Trillium Biopassive Surface coating of the oxygenator on circulating platelet count drop during cardiopulmonary bypass.

An investigation was conducted to evaluate the effect that surface coating of the hollow-fiber membrane oxygenator had on circulating platelet count drop during cardiopulmonary bypass (CPB). Sixty patients undergoing non-emergency myocardial revascularization for coronary artery disease were randomly divided into two groups. Group one (n = 32) received the Carmeda-coated Maxima-Plus PRF oxygenator while the patients in Group two (n=28) received the Trillium-coated Affinity oxygenator during CPB. The net platelet count drops for the pump specimen (15-20 min after the initiation of bypass) for the Carmeda and the Trillium groups were 3.6 +/- 15.8% and 6.2 +/- 10.2%, respectively. The net platelet count drop for the warming specimen for the Carmeda and the Trillium groups were 2.9 +/- 19.4% and 0.5 +/- 11.0%, respectively. There were no statistically significant differences between the groups. The authors conclude that using either the Carmeda-coated Maxima-Plus PRF oxygenator or the Trillium-coated Affinity oxygenator afford similar benefits in regards to preserving circulating platelet counts during bypass.

Effect of Trillium Biopassive Surface coating of the oxygenator on platelet count drop during cardiopulmonary bypass.

The new Trillium Biopassive Surface is a coating designed to minimize the adsorption of protein and the attachment of cells. In previous studies, we were able to demonstrate that, by coating the bypass circuit with small amounts of albumin, the drop in circulating platelet count seen with the newer low-prime hollow-fiber membrane oxygenators is eliminated. A study was undertaken to compare the Avecor Affinity oxygenator with albumin in the prime with the Trillium-coated Affinity. Fifty-six patients undergoing nonemergency open-heart surgery were randomly divided into two groups. One group (Albumin) received the Affinity oxygenator with 10 ml of 25% albumin added to the pump prime. The other group (Trillium) received the Trillium-coated Affinity oxygenator. To normalize the data for the effects of hemodilution, the mean net platelet count drop on bypass was calculated for each group. The Albumin group had a net platelet count drop of 0.81+/-9.78%, while the Trillium group had a drop of 1.58+/-13.0%. There was no significant statistical difference between the two groups. From our investigation, we concluded that Trillium Biopassive Surface coating affords the Affinity oxygenator the same protective effects on circulating platelet counts as adding albumin to the prime.

Albumin in the cardiopulmonary bypass prime: how little is enough?

Previous studies have demonstrated high transoxygenator pressures with noncoated hollow-fiber membrane oxygenators. These reports have been associated with dramatic platelet count drops during cardiopulmonary bypass (CPB). It has also been shown that adding human albumin to the prime of the bypass circuit reduces, if not eliminates, these problems. This study was conducted to determine what is the smallest amount of albumin added to the prime that will still display its protective effects. Eighty patients undergoing nonemergency open-heart surgery were randomly divided into four groups. Groups I and II received the Sarns Turbo 440 oxygenator with 0.0375 g of albumin/100 ml of prime and 0.125 g of albumin/100 ml of prime, respectively, added to the pump prime. Groups III and IV received the Medtronic Maxima-PRF oxygenator with 0.0375 g of albumin/100 ml of prime and 0.125 g of albumin/100 ml of prime, respectively, added to the pump prime. Pre-CPB, on CPB (15-20 min after the initiation of bypass) and warming hemoglobin, hematocrit and platelet counts were drawn on all patients. Net platelet count drop, which accounted for hemodilutional effects, was calculated for all specimens and compared to previous results obtained from the test oxygenators without albumin in the prime. The net platelet count drops for the study groups were as follows: Sarns oxygenator with no albumin in the prime = 11.8+/-12.5%; Sarns oxygenator with 0.0375 g of albumin/100 ml prime = -3.7+/-10.8%; Sarns oxygenator with 0.125 g of albumin/100 ml prime = -2.0+/-12.6%; Medtronic oxygenator with no albumin in the prime = 20.1+/-14.5%; Medtronic oxygenator with 0.0375 g albumin/100 ml prime = -6.9+/-8.7%; and Medtronic oxygenator with 0.125 g albumin/100 ml prime = -14.0+/-12.4%. Our results illustrate that adding as little as 0.0375 g albumin/100 ml prime (3 ml of 25% solution/2000 ml of prime) to the pump prime illicits the beneficial effects of surface coating on platelet loss during CPB.

Effect of surface coating on platelet count drop during cardiopulmonary bypass.

This study was designed to investigate the effect of surface coating on platelet count drop during cardiopulmonary bypass (CPB). Sixty patients undergoing open-heart surgery were randomly divided into three groups each receiving a different type of coated hollow-fiber membrane oxygenator. The patients were given either an uncoated oxygenator (noncoated group), an oxygenator coated with Carmeda (Carmeda group) or an uncoated oxygenator with albumin in the priming solution (albumin group). Comparisons were made in platelet count pre-CPB, on bypass (15-25 min) and during the warming period. Calculations were used to account for the effect of hemodilution. The albumin group had significantly lower platelet count drops (-4.8+/-7.1%) than the Carmeda group (11.0+/-8.3%) and the noncoated group (20.3+/-14.5%). Carmeda surface coating demonstrated some beneficial effects, but to a lesser degree than the albumin.

Potential problem when using the new lower-prime hollow-fibre membrane oxygenators with uncoated stainless steel heat exchangers.

A prospective study was conducted to evaluate the trans-oxygenator pressure gradient across three different hollow-fibre membrane oxygenators during routine cardiopulmonary bypass (CPB). Sixty consecutive open-heart surgery patients were randomly divided into three groups each receiving a different model of membrane oxygenator. Inlet and outlet pressures, as well as patients' pressures, blood flow, revolutions per minute and tympanic membrane temperature were recorded every 15 min during CPB. Within the study groups, there were subsets of patients who exhibited high trans-oxygenator pressures. Although most of these episodes were transient and resolved over a period of time, there were several cases during which the high trans-membrane pressures persisted, resulting in decreasing oxygenator performance. In one such case, oxygenator change-out was required. After extensive analysis and review, the only similarities or correlation that could be made were with the marriage of the newer lower-prime hollow-fibre membrane oxygenators (with corresponding narrow blood path) and the integral uncoated stainless steel heat exchangers. Further study needs to be performed to pinpoint the mechanism and pathophysiology that are involved in this phenomenon.

The effect of low-dose epsilon-aminocaproic acid on patients following coronary artery bypass surgery.

The effect of low-dose epsilon-aminocaproic acid (EACA) on the postoperative course of 46 patients was studied. Patients undergoing coronary artery bypass grafting were randomly selected in two groups. Group 1 (20 patients) received 5 g EACA upon initiation of cardiopulmonary bypass (CPB). Group 2 (26 patients) received no antifibrinolytic drugs prior to CPB. Neither group received antifibrinolytic drugs after CPB. There was no significant difference between the two groups' blood usage on CPB: 0.65 units in Group 1 and 0.60 units in Group 2. After CPB, blood usage significantly differed: 2.2 +/- 1.7 (SD) units in Group 1 and 3.9 +/- 3.0 units in Group 2 (p = 0.033). Significant difference was also demonstrated in postoperative blood loss in the first 24 hours: 1610 +/- 531 ml in Group 1 versus 2025 +/- 804 ml in Group 2 (p = 0.043). Pre-CPB administration of low-dose EACA significantly decreases blood loss and blood usage in the postoperative period.

Use of cardioplegia delivery equipment for rapid warm volume replacement after cardiopulmonary bypass.

Often, after cardiopulmonary bypass involving aortic dissection, aortic root replacements, or valve conduits, rapid volume replacement with blood products is essential to obtain hemostasis and patient survival. We describe a method of using cardiopulmonary bypass equipment for rapid warm volume replacement and infusion of remaining residual volume in the cardiopulmonary bypass circuit after a cardiac operation.

Obstruction of the true lumen during retrograde perfusion of type I aortic dissections: a simplified solution.

Retrograde perfusion of the false lumen in cases of type I dissection of the thoracic aorta may not permit reperfusion of the coronary arteries when the aortic cross-clamp is removed. We have employed a Y connector between the coronary perfusion outlet of the oxygenator and cardioplegia delivery system. This allows reperfusion of the coronary arteries through the ascending aortic graft. As cardiopulmonary bypass is discontinued, the true aortic lumen is reexpanded and the false lumen collapsed by forward flow of blood from the heart. The successful use of this system is described.

Rechargeable silver-modified mercuric oxide-zinc cell for cardiac pacemakers.

Tests were conducted on rechargeable mercury-zinc pacemaker batteries under simulated and actual biologic conditions, using a variety of discharge rates and charging schedules. In tests on 96 cells at a 6.4 milliampere (ma) discharge, recharging once every 15 months of simulated pacing at a 25 microampere (mua) drain, the earliest cell failure occurred after an equivalent of 50 years of pacing. The mean pacing equivalent for all 96 cells was more than 140 years. In 6.4 ma discharge tests on 24 cells, recharging once every 8 days of simulated pacing, only 1 cell in 24 failed after an equivalent of more than 500 years of pacing (actual time 2 years). In tests on 13 cells pacing at a 200 mua drain without recharging, the simulated mean duration of pacing before total discharge was 4.8 years. Seven other cells at a 200 mua drain with periodic recharging continue to function normally after more than 7 years of actual time, simulating 56 years of pacing at a 25 mua drain. Cardiac pacemakers using the rechargeable mercury-zinc cell have been implanted in animals for more than 2 1/2 years and in patients for more than 1 year with all units continuing to function satisfactorily. It has been demonstrated unequivocally that a rechargeable mercury-zinc pacemaker will function continuously for more than 4 years without recharging and that periodic recharging will extend pacing life far beyond that predicted for lithium and nuclear primary power sources.

Chronic testing of a pacemaker that needs recharging only once every four years.

Since 1967, three series of rechargeable single-cell silver-mercuric oxide-zinc pacemakers have been implanted in dogs with complete heart block. The five nonhermetic units in series 1 failed after less than or equal to 18 months, primarily due to prototype cell deficiencies, although one cell functioned for eight years. The six units in series II contained improved cells, but failed due to gradual transepoxy fluid absorption after less than or equal to 31 months. All rechargeable cells were salvaged and dried, and, seven years after their manufacture, they continue to power pacing circuits. Series III now totals 20 doubly hermetically sealed units, tested for up to three years (total more than 300 months or 26 years), with no pacemaker failures. Accelerated tests indicate a minimum life of more than 50 years. A clinical trial is in progress.

The mechanism of myocardial damage following potassium citrate (Melrose) cardioplegia.

To determine the reasons for clinical failure of Melrose solution, potassium arrest was studied in isolated working rat hearts. Eight control hearts were stable for 2-1/2 hours. After 1/2 hour of work, 42 experimental hearts were subjected to 1 hour of ischemis by aortic cross-clamping with unmodified ischemia in eight hearts and ischemia with simultaneous intracoronary injection of 5 ml. of 4 degrees C. (1)Krebs-Henseleit buffer in seven hearts (2)potassium chloride buffer in six hearts, (3)potassium citrate buffer in eight hearts (both 26 mEq. per liter of K, approximately 300 mOsm. per liter), (4)Melrose solution in seven hearts (greater than 200 mEq. per liter of K, greater than 400 mOsm. per liter), (5)hypertonic potassium citrate buffer in six hearts (26 mEq. per liter of K, greater than 400 mOsm. per liter). The pH of all solutions was 7.8 plus or minus 0.1. After recovery isotonic potassium citrate- and potassium chloride-arrested hearts and time-matched control hearts showed no significant differences in cardiac output, coronary flow, systolic pressure, or heart rate. Hypertonic potassium citrate decreased the recovery of cardiac function after arrest and Melrose arrest was not significantly different from unmodified ischemia. Intracoronary cold isotonic Krebs-Henseleit buffer was better than Melrose arrest but inferior to 26 mEq. er liter of potassium arrest. Arrest with 26 mEq. per liter of potassium augments perfusion hypothermia and prevents significant functional and histologic myocardial damage during 1 hour of ischemis. Previous authors assumed that hypertonicity and citrate were responsible for poor results with Melrose solution, but high potassium concentration is the major deleterious factor with hypertonicity playing a contributory role.