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Biomedical subjects

W K Vaughn

Publications and source records attributed to W K Vaughn.

At least 37 records · Page 2Linked to original sources
PubMed1995

Blood use in patients undergoing repeat coronary artery bypass graft procedures: multivariate analysis.

BACKGROUND: The prevailing clinical opinion is that patients undergoing repeat coronary artery bypass graft (CABG) operation require more blood transfusions than do patients undergoing primary CABG operation. To determine the extent of this increased demand and the variables responsible for it, the cases of 196 patients who had undergone primary procedures and 65 patients who had had repeat procedures at the same institution were reviewed. STUDY DESIGN AND METHODS: To analyze the differences in transfusion requirements for these two groups, the following data were obtained: number of transfusions given between the time of surgery and the time of hospital discharge; preoperative hemoglobin (Hb), hematocrit (Hct), prothrombin time, and platelet count; Hb and Hct at hospital discharge; time the patient was on cardiopulmonary bypass; number and type of grafts; estimates of intraoperative blood loss; and chest-tube blood shed during the first 48 hours after surgery. RESULTS: The groups were comparable with respect to age, body weight, preoperative Hb and Hct, number of grafts, and aspirin exposure. Patients in the repeat group had 35-percent greater blood loss and required 75-percent more blood components than did the patients undergoing primary procedures. The mean number of blood components transfused per patient was as follows: red cells, 3.8 +/- 0.5 units in repeat patients and 2.2 +/- 0.2 units in primary patients (p = 0.002); platelets, 2.9 +/- 0.9 vs. 1.1 +/- 0.2 (p = 0.043); fresh-frozen plasma, 1.6 +/- 0.4 vs. 0.8 +/- 0.1 (p = 0.044). Analysis of variables by regression method for repeat patients showed a predictive effect of blood loss (p < 0.0001), prolonged time on cardiopulmonary bypass (p < 0.0001), preoperative Hb (p = 0.0003), and aspirin exposure (p = 0.0094) on red cell transfusion rate in repeat patients (R-square = 0.7778, Prob > f = 0.0001). CONCLUSION: Repeat CABG patients have higher transfusion rates. These findings may be attributed to the increased microvascular bleeding, prolonged time on cardiopulmonary bypass, lower preoperative Hb, and the use of preoperative antiplatelet medications.

Aged↗
PubMed1995

Results of a national survey on anticoagulation for PTCA.

In order to assess the current practice patterns in the United States for anticoagulation during PTCA, a survey was sent to the ACC membership. A total of 377 surveys from physicians performing PTCA were tabulated; 5 (1.3%) respondents performed < 20 PTCAs/year, 128 (34.0%) performed 20-75 PTCAs/year, 141 (37.4%) performed 75-150 PTCAs/year, 98 (26.0%) performed > 150 PTCAs/year and 5 (1.3%) did not report their volume. Seventy-eight (20.7%) were at university hospitals 153 (40.6%) were at other teaching hospitals, 142 (37.7%) were at non-teaching hospitals and 4 (1.1%) did not report their institutional affiliation. A total of 76.8% of respondents routinely started with a 10,000 U bolus of heparin, while only 3.2% of respondents used only a weight-adjusted heparin bolus. Fifty-nine percent of respondents routinely used intra-procedure heparin infusions, usually 1000 U/hr. Anticoagulation monitoring was used by 92.6% of respondents during PTCA, almost always activated clotting times (ACTs). Of the 335 physicians who used ACTs to guide heparin therapy during PTCA, 59.1% used the Hemochron device, 16.7% used the HemoTec device, and 24.2% did not know which machine they used. Lower volume operators and operators at non-teaching hospitals were more likely not to know the type of ACT machine used. Post-procedure heparin infusions (usually titrated to an aPTT > 2 x control) were used by 70.3% of respondents. Lower volume operators were more likely to use post-procedure heparin infusions. Thus, heparin therapy for PTCA continues to be largely empiric, although the vast majority of cardiologists surveyed use ACT-guided heparin therapy for the procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1994

Enhanced thrombolysis, reduced coronary reocclusion and limitation of infarct size with liposomal prostaglandin E1 in a canine thrombolysis model.

OBJECTIVES: The purpose of this study was to test the hypothesis that liposomal prostaglandin E1 (TLC C-53) would result in more rapid thrombolysis, less reocclusion and smaller infarct size when administered with heparin and streptokinase in a canine thrombolysis model. BACKGROUND: In experimental animals, prostaglandin E1 has been shown to augment thrombolysis, improve coronary flow and reduce infarct size when infused directly into the left atrium. TLC C-53 is a stable preparation of prostaglandin E1 bound by phospholipid microspheres that produces fewer adverse hemodynamic effects during intravenous use. METHODS: To investigate the effects of TLC C-53 on coronary patency and infarct salvage, we studied 30 conditioned open chest dogs. After coil-induced left anterior descending coronary artery occlusion and 1 h of clot maturation, the dogs were randomly assigned to receive a 10-min intravenous infusion of either TLC C-53 (2 micrograms/kg body weight) or placebo. Both groups then received intravenous heparin and streptokinase. Hemodynamic variables and Doppler coronary flow were monitored, and myocardial blood flow was determined using radioactive microspheres. Infarct size was assessed with triphenyltetrazolium chloride staining. RESULTS: Thrombolysis time was accelerated from 79 +/- 38 to 47 +/- 9 min (mean +/- SD), and coronary patency was greater (100% vs. 50%) with TLC C-53 than with placebo (p < 0.05). Moreover, for arteries that recanalized, coronary Doppler flow and myocardial perfusion were more severely impaired with placebo. Infarct size as a percent of the area at risk was higher (p < 0.05) with placebo (51 +/- 15%) than with TLC C-53 (33 +/- 14%). Neutrophil infiltration into ischemic myocardium determined by myeloperoxidase assay was also significantly greater in the placebo group. CONCLUSIONS: TLC C-53 administered intravenously before thrombolytic therapy resulted in a significant acceleration of thrombolysis time, improvement in coronary patency and blood flow during reperfusion and a reduction in infarct size.

Alprostadil↗
PubMed1994

Manifestations of diabetes mellitus on mouse preimplantation development: effect of elevated concentration of metabolic intermediates.

The metabolic derangements of pregnancies complicated by diabetes mellitus, specifically hyperglycaemia and hyperketonaemia, are known to be teratogenic during the period of organogenesis in animals. We have shown previously that poorly controlled diabetes mellitus impairs in-vivo and in-vitro mouse preimplantation embryo growth, and that culturing embryos in elevated glucose concentrations only partially recreates this developmental delay. To extend this observation we examined the effect on mouse preimplantation embryo growth of elevated concentrations of other metabolic intermediates, which may be deranged in diabetes mellitus, namely lipids, lactate, glycerol, amino acids, and ketones. Two-cell embryos from ovulation-induced B6C3F1 mice were cultured for 72 h in the presence of added lipids (250 mg/dl), lactate (5 mM), glycerol (160 microM) or mixed amino acids (8.5% travasol, 7 mM) and showed no significant difference in growth over 72 h versus their control groups. However, growth of preimplantation embryos in acetoacetate (10 mM) or in the racemic mixture of DL-beta-hydroxybutyrate (16 and 32 mM) revealed marked retardation versus controls when assessed either by distribution of developmental stages over time (24, 48, 72 h, P < 0.001) or by the difference in the average rank of sums indicating a delay in maturation (P < 0.0001). We conclude that elevated ketone concentrations adversely affect preimplantation embryo development. These findings extend previous studies which correlate uncontrolled diabetes mellitus as well as hyperglycaemia with abnormal organogenesis, and demonstrate that exposure to metabolic derangements may also hinder reproductive performance at even earlier stages in gestation.

3-Hydroxybutyric Acid↗
PubMed1993

A model to predict survival at time of postcardiotomy intraaortic balloon pump insertion.

To facilitate timely application of new forms of cardiac support to patients at highest risk after cardiotomy despite conventional support with the intraaortic balloon pump, an accurate prediction of survival must be available at the time of weaning from cardiopulmonary bypass. We, therefore, acquired 240 demographic, disease, and perioperative characteristics of 322 patients (mortality rate, 48.4%) who required IABP support to separate from bypass. Four variables available before or within 10 minutes of the first attempt at weaning from bypass significantly predicted mortality by stepwise logistic regression: complete heart block as demonstrated by need for temporary pacing at weaning (p < 0.001), advanced age (p < 0.002), preoperative blood urea nitrogen concentration (p = 0.036), and female sex (p = 0.048). An equation generated by the logistic model predicted a 72.2% survival rate in the 25% of patients at least risk (actual survival rate, 71.6%); in the 25% at greatest risk, death was predicted in 73.0%, and the actual mortality rate was 74.1%. The equation was then prospectively applied to 330 intraaortic balloon pump-supported patients managed at another institution. The overall mortality rate there was 41.2%; in the 25% at least risk, predicted survival rate was 70.5% (actual survival rate, 77.1%), and in the 25% at greatest risk, predicted mortality rate was 75.7% (actual mortality rate, 62.7%). Thus, retrospectively at one institution and prospectively at another, the equation generated by this model based only on data available at the time of weaning from bypass was able to define one subgroup of patients 2.6 to 2.7 times as likely to die as another subgroup from within similar cohorts.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Peripheral organ perfusion augmentation during left ventricular failure. A controlled bovine comparison between the intraaortic balloon pump and the Hemopump.

Despite the use of inotropic therapy and the intraaortic balloon pump (IABP), inadequate peripheral organ perfusion and subsequent multiorgan failure from left ventricular dysfunction is a major cause of death following cardiac surgery. To compare the end-organ perfusion provided by the IABP with that of the recently developed Hemopump Cardiac Assist System, blood flow from visceral organs was measured by ultrasonic flow probes during separate periods of support with each of these pumps. Ten calves underwent coronary artery ligations with beta-receptor blockade; hemodynamic parameters were recorded before the induction of failure, during unsupported cardiac failure, and during Hemopump and IABP support. Improvement in mean cardiac output, mixed venous oxygen saturation, and pulmonary artery wedge pressure was significantly greater (p < 0.05) during Hemopump support than during IABP support. Renal artery flow was significantly greater during Hemopump support (276 +/- 74.2 cc/min) than during IABP support (164 +/- 79.6 cc/min). Hepatic artery flow was significantly greater during Hemopump support (34.7 +/- 25.7 cc/min) than during IABP support (24.4 +/- 18.9 cc/min), and portal vein flow was significantly greater during Hemopump support (1588 +/- 315 cc/min) than IABP support (1259 +/- 310 cc/min). There were no significant differences, however, between carotid artery flow during Hemopump support (292 +/- 171 cc/min) and that during IABP support (317 +/- 204 cc/min). We conclude that renal, hepatic, and mesenteric perfusion provided by the nonpulsatile Hemopump is superior to that of the IABP in this bovine model of left ventricular failure. Therefore, the Hemopump may be more effective in preventing multiorgan failure during recovery of ventricular function.

Animals↗
PubMed1992

Factors affecting the waiting time of cadaveric kidney transplant candidates in the United States.

UNLABELLED: OBJECTIVE--To evaluate the relative impact of various factors that could account for differences in waiting time of cadaveric kidney transplant candidates (eg, black and sensitized patients). DESIGN: --A cohort study using multivariate analyses to identify associations between 36 patient, donor, and center factors with waiting time for all US cadaveric kidney transplant candidates listed between October 1, 1987, and June 30, 1990. SETTING--All US kidney transplant centers. PATIENTS--The study included 23,468 cadaveric renal transplant candidates on active waiting status. RESULTS--The patient characteristics most significantly associated with increased waiting time (adjusted for all other variables) were immunologic and included presensitization to HLA antigens, O or B blood type, candidacy for a repeat transplantation, and expression of rare HLA-A or HLA-B antigen phenotypes. Nonimmunologic factors also affected waiting times, which were significantly shorter for patients younger than 15 years vs those aged 15 through 44 years (8.4 vs 12.9 months, respectively; P less than .0001), for those listed at multiple centers vs one center (7.0 vs 13.3 months, respectively; P less than .0001), or for white vs black patients (11.9 vs 15.4 months, respectively; P less than .0001). Local transplant center characteristics associated with a significantly shorter waiting time included a small number of transplantation candidates, a high (greater than 35 per million population) local kidney organ recovery rate, and an approved variance from the Organ Procurement and Transplantation Network allocation algorithm. CONCLUSIONS--The time renal transplant candidates must wait for kidney transplantation is influenced by several factors in addition to those expected due to immunologic reasons of donor incompatibility, the algorithms used for organ distribution, or the effectiveness of local kidney recovery. The impact of these factors should be considered as the current US system for allocating scarce donor organs for kidney transplantation is modified.

Black or African American↗
PubMed1991

The use of "marginal" donors for organ transplantation. The influence of donor age on outcome.

The influence of donor age on outcome was studied in the recipients of 12,131 cadaveric renal allografts, 3026 heart allografts, and 2913 liver allografts with followup information in the UNOS data base for transplants performed between 10/1/87 and 12/31/89. For recipients of kidney transplants, donors of ages 6-15 had significantly better 1-year graft survival than donors of ages 56-65, but the difference was only 7.0%. Donors of age greater than 65 actually did better than donors ages 56-65, but donors less than or equal to 5 were less satisfactory. Kidneys from older donors survived as well as kidneys from younger donors in patients with repeat transplants, diabetes, black race, age over 45, O HLA or 5 and 6 HLA matches, delayed graft function, shared kidneys and PRA greater than 50. For kidney recipients, multifactorial analysis by Cox regression showed that donor age was less important than the use of ALG, donor race, diabetes or peak PRA in ages 16-45, delayed function, repeat transplant, and HLA match. Recipients of heart transplants from donors ages 45-55 had 1-year graft survival that was 8.4% less than recipients of hearts from donors age 16-45. However, 32.7% of heart patients died during the first 12 months after listing without benefit of a transplant. Liver transplant recipients of donor ages 16-45 had 10.8% better 1-year graft survival than recipients of donors greater than 45, but a greater percentage of older donors were transplanted to high risk and older recipients. Tragically, 24.3% of patients listed for liver transplantation died within 12 months without a transplant. This analysis shows that satisfactory graft survival can be achieved using older donors and that age in itself should not be a barrier to organ donation, providing that organ function is normal and that specific disease of the organ is absent.

Adolescent↗
PubMed1991

Effect of diabetes mellitus on mouse pre-implantation embryo development.

Fifteen spontaneously diabetic, non-obese mice (NOD strain), 17 non-diabetic NOD mice (in which diabetes had not yet developed) and 9 diabetic NOD mice were treated with insulin. All animals were superovulated with 5 iu of pregnant mares' serum gonadotrophin followed 48 h later by 5 iu human chorionic gonadotrophin (hCG) and mated overnight with NOD males of proven fertility. To assess in-vitro and early in-vivo development, 23 NOD mice were killed 72 h after hCG treatment. Embryos were recovered from oviduct flushings and cultured in Ham's F-10 medium with 0.1% bovine serum albumin at 37 degrees C in an atmosphere of 5% O2, 5% CO2, and 90% N2. Development was assessed at intervals of 24 h for 72 h. Compared with embryos from non-diabetic NOD mice (n = 81), embryos from diabetic NOD mice (n = 68) demonstrated marked impairment in growth assessed by distribution of developmental stages at each observation period (24, 48, 72 h, all P less than 0.001) and by overall rates of progression of developmental stages (P less than 0.01). In diabetic NOD mice treated with insulin, embryo development (n = 7) was not significantly different from that of embryos from non-diabetic NOD mice (n = 81), but was significantly faster than in embryos from diabetic NOD mice not treated with insulin (n = 68) (P less than 0.001, for all periods, overall rate P less than 0.01). To assess late in-vivo growth, 18 NOD mice were killed 120 h after hCG.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Algorithm for the national allocation of hearts and heart-lungs.

The algorithm used for the equitable allocation of hearts and heart-lungs to potential recipients in the United States is presented. A brief history of the development of the algorithm is followed by discussion of the input criteria and implementation. The current computer system is discussed with emphasis on access by organ procurement personnel.

Algorithms↗
PubMed1990

Manifestation of diabetes mellitus on mouse follicular and pre-embryo development: effect of hyperglycemia per se.

Animal models of diabetes mellitus during pregnancy have repeatedly suggested that maternal hyperglycemia was teratogenic during organogenesis, and thus may contribute to diabetic teratogenesis. However, little attention has been focused on the effects of hyperglycemia on pre-organogenic development. In this report, we examine the effect of hyperglycemia (950 mg glucose/dL) on the development of mouse pre-embryos in vitro. B6C3F1 mice were superovulated with 5 U pregnant mare serum gonadotropin (PMSG) followed by 5 U human chorionic gonadotropin (hCG) 48 hours later. Two cell pre-embryos were recovered 48 hours later, pooled together, and randomly assigned to different treatment groups. Cultures were performed in HAM's F-10 media (Gibco, Long Island, NY) with 0.1% bovine serum albumin (BSA; Sigma, St. Louis, MO) BSA at 37 degrees C in an atmosphere of 5% CO2, 5% O2, and 90% N2 with 15 to 30 embryos per milliliter of culture fluid. Cultures were viewed daily at 24, 48, and 72 hours after culturing, with recording of the development. Compared with control pre-embryos (n = 216), embryos cultured in elevated glucose levels (950 mg/dL) (n = 226) demonstrated marked growth retardation as assessed both by (1) distribution of developmental stages at each observation point (24 hours, P less than .001; 48 hours, P less than .006; 72 hours, P less than .001); and (2) a difference in the average rank sums indicating a delay in maturation (P less than .005). In a second protocol group, pre-embryos were cultured in an equivalent amount of L-glucose; no impairment in development compared with controls was noted.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Organs for transplantation: analysis of 27,000 cadaveric donor organs.

Organs from brain-dead cadaveric donors have been increasingly used for saving lives and preserving health. During the 5 calendar years 1984 through 1988, specific organ recovery patterns were reported for 10,488 donors of 27,833 vascular organs. Transplantation of 18,277 kidneys, 3425 hearts, 2957 livers, and 411 pancreatic grafts (as well as smaller numbers of lung, intestine, heart-lung, and multivisceral grafts) represented an organ utilization rate exceeding 90%. Organ sharing was common and had a beneficial effect overall. Renal allografts from multiorgan donors showed better early function and long-term survival. A steady decrease in organ wastage has been accompanied by a substantial increase in numbers of cadaveric multiorgan donors. The resource of life-saving cadaveric organs is effectively and widely dispersed, allowing increasingly common treatment of end-stage organ failure by transplantation.

Age Factors↗
PubMed1990

Living-donor renal transplantation in SEOPF. The impact of histocompatibility, transfusions, and cyclosporine on outcome.

The impact of haplotype match (HM), pretransplant transfusions, and cyclosporine use were examined for living-donor renal transplants performed among 49 centers in the South-Eastern Organ Procurement Foundation (SEOPF) from November 1983 to June 1988 with follow-up through March 1989. During this period, 750 2-HM, 1246 1-HM, and 120 0-HM living-donor transplants were performed at 46, 47, and 27 centers, respectively. Demographic comparisons of the HM categories demonstrated the greatest use of cyclosporine and donor-specific transfusions in the 0-HM group, and the greatest use of random blood transfusions (RBT) or no blood transfusions (NBT) in the 2-HM group. By univariate and multivariate (Cox regression) analyses, actuarial graft survival was significantly associated with haplotype match, although excellent 3-year graft survival was seen for 0-HM as well as 1-HM and 2-HM first transplant recipients: 74 +/- 5%, 80 +/- 2%, and 85 +/- 2%, respectively. Comparisons were also made among patients receiving DST +/- CsA, RBT +/- CsA, and NBT +/- CsA for each HM group by univariate and multivariate analyses. For 0-HM recipients, DST + CsA was most frequently used and associated with the best long-term survival (86 +/- 5% at 3 years) by univariate analysis. For 1-HM recipients, there were no apparent differences in graft survival between DST and RBT groups +/- CsA by univariate analysis, but the absence of transfusion (NBT +/- CsA) was associated with the poorest 3-year survival (79 +/- 4%). This was confirmed by multivariate analysis, where DST (P less than 0.06) and RBT (P less than 0.02) were each significantly associated with graft survival, and provided relative benefits (vs. NBT) of 0.56 and 0.44, respectively; CsA use was not significantly associated with outcome or a significant benefit. For 2-HM recipients, the poorest results were seen with DST + CsA (78 +/- 6% at 3 years) by univariate analysis; multivariate analysis suggested no benefit with DST or RBT, and an increased risk of graft loss with CsA. These results indicate that the use of pretransplant transfusions and CsA therapy may have differential benefits depending upon HM in living-donor renal transplantation.

Adolescent↗
PubMed1990

Beneficial effect of cyclosporine on renal transplantation. A multicenter long-term study.

Data were collected prospectively on 8581 cadaveric renal transplants performed by institutions of the South-Eastern Organ Procurement Foundation (SEOPF) during the period November 1, 1983 through December 31, 1987. Cyclosporine was the initial then always used immunosuppressant for 5742 of these patients while 1050 never received cyclosporine. The drug was started late in the course of 481 transplants and stopped early in 378 cases. This allowed for 7651 transplants to be analyzed regarding these four categories of cyclosporine use or non-use. Actuarial graft survival for the cyclosporine "ALWAYS" group was 75% at one year, 68% at two years, 62% at three years, and 59% at four years compared with 55%, 49%, 45%, and 43%, respectively for the cyclosporine "NEVER" group (P less than 0.0001). Inclusion of the 930 cases that could not be categorized regarding cyclosporine use or for which actuarial data was not complete allowed all 8581 transplants to be analyzed by multivariate methods. This analysis disclosed significant effects on graft survival due to delayed graft function, prior transplant, recipient race, HLA match, level of PRA, and cyclosporine use. Organ sharing had no effect on graft outcome. While cyclosporine improves outcome in renal transplantation, the importance of other biologic factors affecting graft survival is not diminished by its use.

Cadaver↗
PubMed1990

UNOS: 1989.

This paper provides the current data which has been accrued by the UNOS National Scientific Registry as a result of the mandatory sharing of 6-antigen matched kidneys. The 6-month graft survival does not show, as yet, any benefit for first grafts (N = 72), but does show substantial benefit for repeat grafts (N = 25). No penalty from sharing could be demonstrated since graft survival for local and shared organs was the same. The rationale for two new UNOS policies are discussed: (1) mandatory sharing of phenotypically identical kidneys, (2) the "payback system" for shared kidneys. Finally, some personal comments of the author regarding the importance of the National Organ Procurement and Transplant Network are recorded.

Graft Survival↗
PubMed1990

Liver transplantation in the United States: 1988 to 1989.

Orthotopic liver transplantation was performed more often in 1989 than in 1988. This procedure was performed at 57 institutions in 1988 and at 64 in 1989. Among the 53 institutions in which OLTX was performed in both years, the tendency was to increase volume. Volume in 1988 was not an indicator for volume increase or decrease in the next year. For example, about 60% of the centers which performed 5-9 OLTXs in 1988 had a greater volume in 1989. This was similar to the percentage among centers which performed 30-49 OLTXs in 1988. Only centers which performed at least 100 OLTXs in 1988 increased in volume uniformly (3 centers). There was about a 25% increase in the number of OLTX recipients, and the characteristics of the recipient population changed. In 1989, as compared to 1988, there was a larger proportion of recipients over age 40 with a concomitant proportionate decrease in pediatric recipients. Indications for OLTX were also different. In 1988, biliary atresia and primary biliary cirrhosis were the major diagnoses for which OLTX was performed. In 1989, however, alcoholic cirrhosis was the most prevalent diagnosis among OLTX recipients, accounting for more than 1 of every 7 procedures. We also found that the distribution of UNOS description changed. Significantly more recipients were classified in the best functional group, and significantly more recipients were on life support in 1989 compared to 1988. Whether this reflects a change in the actual functional status of recipients, or change in the management of these patients, is a topic for further research.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗