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R A Vertrees

Publications and source records attributed to R A Vertrees.

34 records · Page 2Linked to original sources
PubMed1991

Arterial-venous perfusion without anticoagulation: the impeller centrifugal pump.

A study was designed to test the effects of the absence of anticoagulation in the extracorporeal circuit. Five swine were subjected to this experiment utilizing the impeller centrifugal pump during which neither heparin nor any other anticoagulant was used. The extracorporeal circuit consisted of polyvinylchloride tubing, a Centri-Med pump and an external stainless steel heat exchanger that was primed with albuminized Ringer's solution. An arterial-venous circuit was employed with oxygenation supplied from the subject's lungs. A series of blood aliquots were analyzed for coagulation at various times throughout the procedure. Following total body cooling using topically applied ice water, the subjects were rewarmed utilizing bypass. Within 10 minutes after the initiation of bypass, the circuits became clotted, rendering perfusion and subsequent warming ineffective. The lab values indicated that intrinsically activated coagulation occurred upon exposure to the extracorporeal apparatus. Flow visualization studies revealed a source of stagnant blood flow in the area around the hub of the pump head. Blood clot was similarly located in this area, with clot extension throughout the return circuit being realized. It is imperative that areas of stagnation be eliminated from extracorporeal circuits, since they may be potential sites for clot formation.

Animals↗
PubMed1990

Heparinless extracorporeal bypass for treatment of hypothermia.

In an attempt to assess the changes occurring to the coagulation profile during internal active core rewarming with partial cardiopulmonary bypass (CPB) without heparin anticoagulation, five pigs were anesthetized, and a model for severe to moderate hypothermia was created. Femoral-femoral bypass with Bio-Pump, heat exchanger, and a membrane oxygenator were used during the rewarming for 64.8 +/- 8.5 minutes. There were no statistically significant changes in platelet count, platelet index, activated clotting time (ACT), partial thromboplastin time (PTT), prothrombin time (PT), fibrinogen, fibrinogen index and fibrin split products (p greater than 0.05). There were no thromboembolic sequelae seen at autopsy. The components of the CPB circuit showed no signs of formation of aggregates or thrombi. The results of this study are attributed to the nonthrombogenic, atraumatic design of the Bio-Pump and the enhanced physiological fibrinolysis seen in the first hour of CPB. We concluded that heparinless CPB may serve as a safe alternative for active core rewarming for severe to moderate hypothermia.

Animals↗
PubMed1990

Preventive effect of Fluosol-DA for paraplegia encountered after surgical treatment of the thoracic aorta. Preliminary results in a dog model.

The effectiveness of Fluosol-DA (Green Cross Corporation, Osaka, Japan) on circulatory dynamics and neurologic outcome in dogs with ischemic spinal cord injury produced by aortic crossclamping was tested. The control group (receiving saline solution) had an elevated mean aortic proximal pressure (112.9 +/- 30.2 mm Hg versus 175.3 +/- 20.5 mm Hg, p greater than 0.05) and a drastic drop in mean distal aortic pressure (112.9 +/- 30.2 mm Hg versus 29.8 +/- 11.2 mm Hg, p less than 0.05). Although the same trend occurred in dogs treated prophylactically with Fluosol-DA, these changes were not statistically significant. However, there was a significant difference in mean distal aortic pressure during the ischemic phase between the two groups (58.9 +/- 16.0 mm Hg versus 29.8 +/- 11.2 mm Hg, p less than 0.05). Postoperatively all animals had mean arterial pressures within the normal range. All dogs in the control group were paraplegic (partial or complete); the treatment group had one dog with partial paraplegia. The difference between the mean neurologic scores of the two groups was of high statistical significance (3.7 +/- 0.5 versus 1.6 +/- 1.0, p less than 0.05). Our preliminary results show that prophylactic use of Fluosol-DA has favorable effects on hemodynamics and neurologic outcome in dogs with spinal cord ischemia produced by aortic crossclamping. The high propensity of the drug to carry oxygen and carbon dioxide and to provide nutritional support to the ischemic area with resultant improvement in local microcirculation and blood rheology are some speculative mechanisms advocated for these changes.

Animals↗
PubMed1990

Platelet-rich plasma reduces postoperative blood loss after cardiopulmonary bypass.

To study the effect of plasma sequestration and reinfusion of platelet-rich plasma on blood loss after cardiopulmonary bypass, 18 patients undergoing heart operations were randomly selected either to have collected or not to have collected approximately 250 ml of platelet-rich plasma before initiating cardiopulmonary bypass with the use of the Haemonetics Plasma Saving System (Haemonetics Corporation, Braintree, Mass.). All patients had standardized anesthesia and cardiopulmonary bypass. After reversal of heparin, autologous platelet-rich plasma was reinfused in nine patients. Thrombocyte counts, hemoglobin, and hematocrit were calculated before, during, and after cardiopulmonary bypass, and 24 and 48 hours postoperatively. Blood loss and total number of transfusions were recorded. Although 9% of the total platelet volume was removed, there were no hemodynamic complications related to the use of the Haemonetics Plasma Saving System. In both groups, significant low levels of thrombocytes, hemoglobin, and hematocrit were seen after cardiopulmonary bypass. Platelet-rich plasma-reinfused patients had a significantly higher number of platelets after heparin reversal. They also had significantly less blood loss after the operation, necessitating 65% less banked blood products (p less than 0.05). We concluded that reinfusion of autologous platelet-rich plasma may serve as an effective and safe way to restore some of the hematologic derangements after cardiopulmonary bypass.

Blood Platelets↗
PubMed1981

Perfusion technology in the hypothyroid patient.

Cardiopulmonary bypass may, by necessity, have to be performed in patients who are frankly hypothyroid. In treating five such patients, all of whom required coronary revascularization, it was noted that fluid balance during perfusion was considerably different than that in the normal population. In order to attempt to evaluate this difference, ten consecutive euthyroid patients having revascularization and the five hypothyroid patients were compared to correlate all fluid absorbed and excreted with the duration of bypass, the serum sodium, and subsequent weight gain. Fluid intake, urine output, and retained fluid were significantly elevated in the hypothyroid as compared to the euthyroid group, while serum sodium following operation was not significantly different. While there are considerable data indicating that hypothyroidism is associated with abnormal salt and water excretion, there is no information concerning the alterations which occur during cardiopulmonary bypass. The present study indicates that hypothyroidism is associated with significant diuresis (without administration of exogenous diuretic agents during cardiopulmonary bypass). The proposed explanation for this diuresis rests with the assumption that with cardiopulmonary bypass and appropriate fluid administration, the contracted blood volume in hypothyroid patients expands acutely and a diuresis results.

Angina Pectoris↗
PubMed1979

A technique of myocardial preservation perfusion.

We present a technique for administering cold cardioplegia that permits the pump technician to conveniently give the fluid. The method is comparable to that used in providing coronary perfusion for aortic valve procedures because it allows controlled volume flow and perfusion pressure. In addition, the technique is inherently safe from infusion of air bubbles.

Heart Arrest, Induced↗
PubMed1979

The time course of myocardial high-energy phosphate degradation during potassium cardioplegic arrest.

Myocardial high-energy phosphate and glucose-6-phosphate levels were determined in the in vivo pig heart model during ischemic arrest and reperfusion to determine the effectiveness of potassium cardioplegia in myocardial protection. Thirty-five pigs were divided into six experimental groups consisting of 2-hour normothermic arrest, 2-hour hypothemic arrest, 2-hour normothermic cardioplegic arrest, and 1-, 2-, and 3-hour hypothermic cardioplegic arrest. Myocardial biopsies from the left ventricle were obtained prior to arrest, every 30 minutes during the arrest interval, and at 30 and 60 minutes of reperfusion. The measurement of adenosine triphosphate and creatine phosphate showed that (1) cardioplegic arrest requires hypothermia to preserve high-energy phosphate levels in myocardial tissue; (2) hypothermia, while not completely protective alone, is more effective than potassium cardioplegia alone in providing myocardial preservation during 2-hour ischemic arrest; (3) the combination of potassium cardioplegia and hypothermia is additive in providing an effective means of maintaining myocardial high-energy phosphate stores during 1, 2, and 3 hours of ischemic arrest; (4) myocardial reperfusion does not allow a return to preischemic adenosine triphosphate (ATP) levels after 2 hours of arrest, except following hypothermic cardioplegia; and (5) extension of the duration of ischemic arrest to 3 hours using hypothermic cardioplegia prevents recovery of high-energy phosphate stores to preischemic levels during reperfusion. Optimal preservation can be achieved during 2 hours of ischemic arrest by using hypothermic potassium cardioplegia. The effects of myocardial reperfusion, however, prevent full ATP and creatine phosphate (CP) recovery following 3 hours of arrest. No other technique studied was as effective in providing myocardial preservation.

Adenosine Triphosphate↗
PubMedDate not supplied

Tumor necrosis factor monoclonal antibody prevents alterations in leukocyte populations during cardiopulmonary bypass.

Tumor necrosis factor-alpha (TNF-alpha) has been implicated as causing the systemic inflammatory response to cardiopulmonary bypass (CPB) that contributes to the postoperative sequelae of coagulopathy, increased capillary permeability, leukocytosis, fever, and multiple organ dysfunction. To define the role of TNF-alpha on leukocyte populations during CPB, pigs (n = 6) were pretreated with 20 mg TNF-alpha monoclonal murine antibody before normothermic CPB (2 hr) in a blinded prospective randomized study with saline used as a control (n = 6). The leukocyte response to CPB was measured at 10, 30, 60, and 120 min during CPB and at 60 and 120 min after CPB. Repeated measures analysis of variance was performed and the null hypothesis was discarded at the 5% level. The control group displayed the typical leukocyte profile associated with CPB: and initial leukopenia (36% reduction) followed by leukocytosis (11% increase, P = 0.0001). The initial leukopenia was due to a fall in both polymorphonuclear neutrophils (33% reduced, P < 0.05) and monocytes (37% reduced, P < 0.05). In the TNF-alpha monoclonal murine antibody group the total leukocyte profile did not change significantly from baseline, (8.7% reduction to a 16% increase, P = 0.24) nor were there significant changes in populations including neutrophils and lymphocytes. In the treatment group the initial reduction in monocytes was prevented and total circulating monocytes increased during bypass. The experimental data suggest that TNF-alpha may play an important role in the early alterations in leukocyte populations associated with CPB, and TNF-alpha monoclonal murine antibody pretreatment ameliorates the leukocyte response.

Animals↗
PubMedDate not supplied

Heparin clearance profiles after systemic anticoagulation using a heparin removal device system.

An extracorporeal heparin removal device system (HRDS) based on plasma separation and affinity adsorption has been developed to reduce the risks of protamine-related adverse reactions. The heparin clearance profile of the HRDS was characterized by the first-order exponential depletion. A mathematical model was established to predict the time to achieve 85% heparin removal for different body weights at 700 ml/min and 1400 ml/min extracorporeal HRDS blood flow. With an HRDS flow of 700 ml, 85% of total body heparin removal cannot be achieved within 30 min for subjects greater than 50 kg. With an HRDS flow of 1400 ml/min, 85% heparin removal can be achieved within 32 min for subjects larger than 90 kg. Such model predictions were validated in an adult swine (n = 10) model of 60-min, hypothermic (28 degrees C) cardiopulmonary bypass (CPB). Animals were given 300 U/kg intravenous heparin and 5000 U heparin in the circuit prime for initial heparinization, with subsequent heparin given to maintain activated clotting time above 450 sec. Immediately following CPB, plasma heparin concentration as determined by anti-factor Xa assays was 4.40 +/- 1.08 U/ml in the 700 ml/min group and 4.78 +/- 0.70 U/ml in the 1400 ml/min groups, respectively (p > 0.05). Target HRDS flow was 700 ml/min for animals below 75 kg and 1400 ml/min for animals above 75 kg. The mean body weight in the 1400 ml/min group (81.4 +/- 3.7 kg) was significantly higher than that in the 700 ml/min group (67.2 +/- 2.2 kg) (p < 0.05), with the actually achieved HRDS flow 658.5 +/- 20.8 and 1437.4 +/- 30.1 ml/min, respectively. During the HRDS run, plasma heparin concentration followed the predicted first-order exponential depletion (r2 = 0.97 for the 700 ml/min group and r2 = 0.99 for the 1400 ml/min group). In the 700 ml/min group, the time needed to achieve 85% heparin clearance was over 40 min, whereas in the 1400 ml/min group, this time was reduced to less than 30 min despite greater body weight. At 30 min on HRDS, the 700 ml/min group had 27.4 +/- 3.7% heparin left in the plasma, whereas the 1400 ml/min group had only 12.6 +/- 2.5% (p < 0.05). The authors conclude heparin clearance by the HRDS can be precisely predicted with the mathematical model of first-order exponential depletion. Increasing the HRDS flow can effectively reduce the time needed to achieve a targeted heparin removal.

Animals↗
PubMedDate not supplied

Significant reduction in circuit pressure with modified plasma separation chamber for a heparin removal device.

The heparin removal device (HRD), using plasma separation and poly-L-lysine (PLL) affinity adsorption, has been shown to be an effective alternative to protamine after cardiopulmonary bypass (CPB). Previous designs of the HRD used standard Luer-Lok ((phi = 2.3 mm) port connections between the extracorporeal tubing and the plasma separation chambers, which resulted in excessively high circuit pressures (> 750 mm Hg) at an HRD flow of 1,400 ml/min. To reduce circuit pressures, we enlarged the connection ports to phi = 4.2 mm, keeping other circuit components and sorbent amounts unchanged. The modified circuit HRD was divided into the SMALL PORT group (phi = 2.3 mm, A = 4.15 mm2) and the LARGE PORT group (phi = 4.2 mm, A = 13.85 mm2) in adult swine (70+/-5 kg) given 300 U/kg heparin. A dual lumen cannula was inserted into the right atrium and connected to the HRD. Inlet pressure ranged from 749+/-42 to 795+/-57 mm Hg in the SMALL PORT group during the HRD run at 1,400 ml/min, whereas it ranged from 345+/-5 to 372+/-34 mm Hg in the LARGE PORT group (p < 0.01 between groups). Likewise, the chamber pressure ranged from 447+/-21 to 452+/-27 mm Hg in the SMALL PORT group and from 190+/-14 to 204+/-19 mm Hg in the LARGE PORT group (p < 0.01 between groups). There were no significant differences in ACT between groups. We conclude that enlarged chamber ports significantly lower circuit pressures for the HRD without changing heparin removal capability.

Adsorption↗
PubMedDate not supplied

A surgical approach to chronic aortomyoplasty in the goat model.

The left latissimus dorsi skeletal muscle of seven male goats was prepared and applied circumferentially to the descending aorta just below the subclavian artery. Stimulation of the neural pedicle of the latissimus dorsi was performed in an attempt to convert it to a fatigue-resistant cardiac-like muscle. Timing of the stimulus was in diastole. Biochemical assays established the conversion, and echocardiography demonstrated aortic compressions in the area of the muscle wrap. Although limited in numbers, the converted latissimus dorsi muscle in the extra-aortic position appears to provide diastolic augmentation.

Animals↗
PubMedDate not supplied

Development of a human to murine orthotopic xenotransplanted lung cancer model.

The goal was to develop a clinically relevant animal model that could be used to assess the efficacy of therapeutic interventions in lung cancer. Two cell lines, noncancerous control (BEAS2-B, immortalized human bronchial-epithelial cell line) and cancerous (BZR-T33, H-ras transformed BEAS2-B) were implanted into nude (athymic) mice. Two groups (n = 10 each) received dorsoscapular subcutaneous injection of 10(6) cells from either cell line. BEAS2-B cells were nontumorigenic, whereas mice with BZR-T33 cells had tumors (9,510 +/- 4,307 mm3) confirmed by histology, and a significantly smaller body weight (BZR-T33, 28.5 +/- 0.49 vs. BEAS2-B, 30.7 +/- 0.75 g, p < .05). The next phase evaluated invasion/metastasis. Two groups (n = 10 each) received 10(6) cells from either cell line injected into tail veins. Animals receiving BZR-T33 cells had a smaller body weight, palpable lung masses (67%), obvious tail masses (44%), and average tumor burden (1,120 +/- 115 mm3), and histology revealed invasion of lung tissue and interstitial hemorrhage. In development of the orthotopic xenotransplanted model, mice (2 groups, n = 10 each) received 10(6) cells from either cell line implanted into the lungs through a tracheotomy. Animals with BZR-T33 cells did not survive past 59 days and had a smaller body weight, increased lung weight, lung masses (100%), and metastatic loci (30%). Magnetic resonance imaging (MRI) confirmed the presence of masses in intubated live mice, later confirmed by histology. In summary, the H-ras transfected cell line developed lung masses following tail-vein injection and endotracheal seeding. Evaluation by MRI allows for a comprehensive model with significant potential in the study of lung cancer.

Animals↗
PubMedDate not supplied

Induction of whole body hyperthemia with venovenous perfusion.

Whole body hyperthermia can be used for the treatment of metastatic cancer and human immunodeficiency virus infections. The therapeutic effects of hyperthermia are dependent upon the actual temperature of the target tissues. Therefore, homogeneous distribution of heat and precise control of temperature gradients is critical. To describe heat distribution during hyperthermia induced by venovenous perfusion, the authors used multiple channel temperature monitoring and a servo-regulated perfusion/heat exchange system. Young swine were randomly assigned to either a heated group (perfusion-induced hyperthermia, target core temperature at 43 degrees C, n = 6), or a control group (perfusion alone, target core temperature at 38 degrees C, n = 6). Blood was drained from the external jugular vein, heated with a computer assisted heat exchange system, and reinfused through the femoral vein at a flow of 10 ml/kg-1/min-1. Temperature probes in the esophagus, right and left tympanic canals, brain, pulmonary artery, arterial and venous blood, rectus spinae muscle, kidney, rectum, bone marrow, bladder, subcutaneous tissue, gluteus, and skin were simultaneously recorded. During the heat induction phase, the maximum water temperature was 54 degrees C, with a heating gradient of the blood (blood in-blood out) at 6 degrees C. The maximum temperature difference between tissues was 3.6 degrees C (kidney and esophagus) during heat induction, but decreased to 1.75 degrees C during maintenance. Bone marrow temperature was consistently 1-2 degrees C below the average core temperature of 43 degrees C throughout the experiment. The authors conclude that venovenous perfusion can predictably induce hyperthermia, but is associated with heterogenous temperature distribution among organs. Further studies are necessary to evaluate different perfusion and heating patterns to achieve homogenous hyperthermia.

Animals↗
PubMedDate not supplied

Parallel dialysis normalizes serum chemistries during venovenous perfusion induced hyperthermia.

Whole-body hyperthermia is currently under investigation as a method to treat systemic malignancies; however, available techniques induce a derangement in serum and urine chemistries. This study was done to determine whether veno-venous perfusion induced hyperthermia (vv-PISH) that incorporated a parallel dialysis system to control blood chemistries would eliminate these heat induced derangements. Adult female Yorkshire swine were divided into perfusion only (group P, n = 6, 62.8 +/- 2.5 kg), and perfusion with dialysis (group PD, n = 6, 63.8 +/- 4.3 kg). In both groups, hyperthermia was induced with a computer assisted jugular-to-femoral venovenous heat exchange/perfusion system primed with a balanced electrolyte solution, operating at 30 ml/min-1/kg-1, which used a thermal gradient induced by blood heated to a maximum of 48 degrees C and a perfusate-to-blood temperature gradient < 10 degrees C during heating. The target core temperature was 43 degrees C for 120 min as measured by the average of the rectal, bladder, esophageal, bilateral tympanic, and pulmonary artery temperatures. Including ramp-up and cool down, the total perfusion interval was 263 +/- 29 min in group P and 240 +/- 18 min in group PD (ns). Serum and urine chemistry values expressed as the mean value +/- SEM were compared before and after hyperthermia treatment. Variables include blood urea nitrogen, creatinine, sodium, potassium, chloride, calcium, magnesium, phosphorus, glucose, total protein, albumin, alkaline phosphatase (ALKP), creatinine kinase, aspartate aminotransferase, alanine aminotransferase (ALT), lactate dehydrogenase (LDH), plasma free hemoglobin, urine specific gravity, pH and urine creatinine. All variables remained within normal ranges for the PD group. In the P group, the following final values were outside the normal range: (normal range) creatinine 2.1 +/- 1 (0.4-1.4) mg/dl, Ca2+ 5.1 +/- 1 (6-13) mg/dl, Mg2+ .8 +/- 0.1 (1.2-10) mg/dl, ALKP 134 +/- 6 (34-122) U/L, ALT 69 +/- 3 (9-51) U/L, and LDH 1291 +/- 237 (300-600) U/L. We conclude that the significant changes in serum and urine chemistries associated with vv-PISH are normalized with the use of a parallel dialysis system and may decrease the incidence of electrolyte associated complications.

Animals↗
PubMedDate not supplied

Efficacy of a heparin removal device in comparison with protamine after hypothermic cardiopulmonary bypass.

To reduce the risks of protamine reactions after cardiopulmonary bypass (CPB), a heparin removal device (HRD) with plasma separation and poly-L-lysine (PLL) affinity adsorption was developed. To compare the efficacy of HRD with that of protamine, blood coagulation variables were evaluated in a swine model of CPB. Female Yorkshire swine were randomly divided into the HRD group (n = 6, weight 79.7 +/- 7.0 kg) and the protamine group (n = 6, weight 79.3 +/- 6.8 kg), and subjected to 60 min of right atrium-to-aortic, hypothermic (28 degrees C) CPB. After weaning from CPB, the right atrium was recannulated with a two-stage, dual lumen cannula in the HRD group. Blood flow was drained from the inferior vena cava, through the plasma separation chamber of the HRD where heparin was bound to PLL, and re-infused into the right atrium. The HRD run time was determined by an established mathematical model of first-order exponential depletion targeted to 90% heparin removal. In the protamine group, protamine was given in a 100 U heparin to 1 mg protamine ratio after CPB in a slow intravenous infusion. Hemodynamics, activated clotting time (ACT), activated partial thromboplastin time (APTT), and heparin concentration were obtained before, every 5 min during, and after the use of the HRD or before and after protamine administration, and 1 and 3 hours after HRD or protamine. Heparin concentration immediately after CPB was 4.90 +/- 0.19 U/ml in the HRD group and 3.94 +/- 0.63 U/ml in the protamine group, respectively (p > 0.05 between groups). The ACT was 994 +/- 7 sec in the HRD group and 768 +/- 55 sec in the protamine group, and APTT was greater than 150 sec in both groups (p > 0.05 between groups). In the HRD group, the HRD run time was determined to be 31.5 +/- 2.4 min for the targeted 90% heparin removal, and the plasma heparin concentration followed first-order depletion kinetics. In the protamine group, the full dose of protamine was administered over 15 min. Immediately after the HRD run or protamine administration, plasma heparin concentration decreased to 0.48 +/- 0.09 U/ml in the HRD group and 0.13 +/- 0.02 U/ml in the protamine group (p < 0.01 between groups); likewise, ACT decreased to 188 +/- 25 sec in the HRD group and 101 +/- 5 in the protamine group (p < 0.01 between groups). The APTT was not significantly different between the groups at any time during the experiment. Plasma heparin concentration and ACT were not significantly different three hours after the HRD run or protamine administration. The authors conclude that the HRD is capable of predictable reversal of systemic heparinization after CPB, and is an alternative to achieve heparin clearance in subjects who may develop adverse reactions to protamine.

Animals↗