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B D Spiess

Publications and source records attributed to B D Spiess.

At least 19 recordsLinked to original sources
PubMed1999

Safety and efficacy of shed mediastinal blood transfusion after cardiac surgery: a multicenter observational study. Multicenter Study of Perioperative Ischemia Research Group.

OBJECTIVE: To examine the efficacy and safety of shed mediastinal blood (SMB) transfusion in preventing allogenic red blood cell (RBC) transfusion. DESIGN: An observational clinical study. SETTING: Twelve US academic medical centers. PARTICIPANTS: Six hundred seventeen patients undergoing elective primary coronary artery bypass grafting. INTERVENTIONS: Patients were administered SMB transfusion or not, according to institutional and individual practice, without random assignment. MEASUREMENTS AND RESULTS: The independent effect of SMB transfusion on postoperative RBC transfusion was examined by multivariable modeling. Potential complications of SMB transfusion, such as bleeding and infection, were examined. Three hundred twelve of the study patients (51%) received postoperative SMB transfusion (mean volume, 554 +/- 359 mL). Patients transfused with SMB had significantly lower volumes of RBC transfusion than those not receiving SMB (0.86 +/- 1.50 v 1.08 +/- 1.65 units; p < 0.05). However, multivariable analysis showed that SMB transfusion was not predictive of postoperative RBC transfusion. Demographic factors (older age, female sex), institution, and postoperative events (greater chest tube drainage, lower hemoglobin level on arrival to the intensive care unit, and use of inotropes) were significant predictors of RBC transfusion. The volume of chest tube drainage on the operative day (707 +/- 392 v 673 +/- 460 mL; p = 0.30), reoperation for hemorrhage (3.1% v2.5%; p = 0.68), and overall frequency of infection (5.8% v 6.6%; p = 0.81) were similar between patients receiving and not receiving SMB, respectively. However, in patients who did not receive allogenic RBC transfusion, there was a significantly greater frequency of wound infection in the SMB group (3.6% v0%; p = 0.02). CONCLUSION: These data suggest that SMB is ineffective as a blood conservation method and may be associated with a greater frequency of wound infection.

Aged↗
PubMed1999

Maintenance of homeostasis in coagulation during cardiopulmonary bypass.

Cardiopulmonary bypass (CPB) represents a massive stimulus that overwhelms the body's homeostatic ability to buffer. Contact activation, the extrinsic cascade, and ongoing cellular interactions all must be considered to understand the coagulation dysfunction that occurs in CPB. Various aspects and the specific effects of these factors as well as their interrelationships are still poorly understood. Since we are dealing with a complex system, the way we approach our investigations must become more rather than less complex. Simply measuring peripheral blood levels of various proteins throughout CPB levels does not fit the important physiologic processes governing homeostasis, as production, clearance, redistribution, and dilution are all constantly at play. A recent study of prothrombin fragment F1.2 levels during CPB is provided as an illustration. Our increasing understanding of aprotinin's mechanisms of action has furthered our basic understanding of coagulation dysfunction in CPB. Further progress requires new thinking, more research, and increasingly complex approaches to the understanding of what drives homeostasis.

Anticoagulants↗
PubMed1998

Hematocrit value on intensive care unit entry influences the frequency of Q-wave myocardial infarction after coronary artery bypass grafting. The Institutions of the Multicenter Study of Perioperative Ischemia (McSPI) Research Group.

OBJECTIVES: No data exist regarding "the best" hematocrit value after coronary artery bypass graft surgery. Transfusion practice varies, because neither an optimal hematocrit value nor a uniform transfusion trigger criterion has been determined. METHODS: To investigate the optimal hematocrit value, we studied 2202 patients undergoing coronary bypass. The hematocrit value on entry into the intensive care unit (IHCT) was categorized into three groups: high (> or = 34%), medium (25% to 33%), and low (< or = 24%). Characteristics and adverse events (outcomes) were compared, and the effect of IHCT on the risk of myocardial infarction was determined by logistic regression. RESULTS: High IHCT (> or = 34%) was associated with an increased rate of myocardial infarction (8.3% vs 5.5% vs 3.6%; p < or = 0.03, high, medium vs low) and with more severe left ventricular dysfunction (11.7% vs 7.4% and 5.7%; p=0.006, high, medium vs low). Mortality rate increased with higher IHCT when all the high-risk subgroups were combined (8.6% vs 4.5% vs 3.2%; p < 0.001, high, medium vs low). By multivariate analysis, IHCT remained the most significant predictor of adverse outcomes (relative risk high vs low 2.22, 95% confidence interval: 1.04 to 4.76). No characteristic, event, medication, or transfusion therapy confounded the relationship between IHCT and outcome. CONCLUSION: High IHCT is associated with a higher rate of myocardial infarction and is an independent predictor of infarction. On the basis of the risk of myocardial infarction, there is no rationale for transfusion to an arbitrary level after coronary artery bypass grafting.

Anemia↗
PubMed1998

Heparin-coated bypass circuits (Carmeda) suppress the release of tissue plasminogen activator during normothermic coronary artery bypass graft surgery.

OBJECTIVES: To study fibrinolysis in a homogeneous first-time coronary artery bypass surgery (CABG) population in whom heparin-coated circuits were used. DESIGN: A prospective, blinded, randomized, placebo-controlled study. SETTING: A university hospital, tertiary care, intraoperative and postoperative intensive care unit. PARTICIPANTS: Twenty-one adult elective primary CABG patients. INTERVENTIONS: Randomized circuit-type centrifugal pump, membrane oxygenator, rigid cardiotomy reservoir, either placebo (n = 10) or heparin-coated (n = 11) (Carmeda; Medtronic Inc., Anaheim, CA). MEASUREMENTS AND MAIN RESULTS: Blood samples were analyzed for tissue plasminogen activator (TPA) activity, TPA antigen, plasminogen activator inhibitor-1 (PAI-1) activity, prothrombin complex F1.2, and antithrombin III (AT-III) at the following times: before cardiopulmonary bypass (CPB), during CPB (30 and 60 minutes), post-CPB, and day 1 postsurgery. TPA activity and antigen increased fivefold in the placebo group during CPB, whereas it did not even double in the heparin-coated group. PAI-1, F1.2, and AT-III were not different between groups. CONCLUSIONS: Heparin-coated CPB circuits reduced TPA release in this homogeneous CABG population with routine heparin/protamine management.

Adult↗
PubMed1998

A second-generation blood substitute (perfluorodichlorooctane emulsion) does not activate complement during an ex vivo circulation model of bypass.

OBJECTIVES: To examine whether a second-generation perfluorocarbon (PFC) blood substitute added to the cardiopulmonary bypass (CPB) prime influences complement production. DESIGN: A prospective, randomized, single-blinded, ex vivo model. SETTING: A university hospital, laboratory, and clinics. PARTICIPANTS: Ten healthy adult consented volunteer blood donors (five men, five women). INTERVENTIONS: Ex vivo closed-loop extracorporeal circuit including membrane oxygenator, tubing, and filter primed with crystalloid or crystalloid plus PFC was circulated for 1 hour with the addition of 500 mL of heparinized fresh human whole blood. MEASUREMENTS AND MAIN RESULTS: Laboratory specimens were drawn from the circuit at 10-minute intervals for 1 hour and measured for complement (C3a, Bb fragment) concentrations, blood gases, fibrinogen concentration, platelet count, and hematocrit. In the PFC group, C3a and Bb fragments were equal to or less than those in the group that received crystalloid alone. CONCLUSION: The second-generation PFC added to the prime of a CPB circuit does not independently increase complement production.

Adolescent↗
PubMed1998

Variability in transfusion practice for coronary artery bypass surgery persists despite national consensus guidelines: a 24-institution study. Institutions of the Multicenter Study of Perioperative Ischemia Research Group.

BACKGROUND: An estimated 20% of allogeneic blood transfusions in the United States are associated with cardiac surgery. National consensus guidelines for allogeneic transfusion associated with coronary artery bypass graft (CABG) surgery have existed since the mid- to late 1980s. The appropriateness and uniformity of institutional transfusion practice was questioned in 1991. An assessment of current transfusion practice patterns was warranted. METHODS: The Multicenter Study of Perioperative Ischemia database consists of comprehensive information on the course of surgery in 2,417 randomly selected patients undergoing CABG surgery at 24 institutions. A subset of 713 patients expected to be at low risk for transfusion was examined. Allogeneic transfusion was evaluated across institutions. Institution as an independent risk factor for allogeneic transfusion was determined in a multivariable model. RESULTS: Significant variability in institutional transfusion practice was observed for allogeneic packed red blood cells (PRBCs) (27-92% of patients transfused) and hemostatic blood components (platelets, 0-36%; fresh frozen plasma, 0-36%; cryoprecipitate, 0-17% of patients transfused). For patients at institutions with liberal rather than conservative transfusion practice, the odds ratio for transfusion of PRBCs was 6.5 (95% confidence interval [CI], 3.8-10.8) and for hemostatic blood components it was 2 (95% CI, 1.2-3.4). Institution was an independent determinant of transfusion risk associated with CABG surgery. CONCLUSIONS: Institutions continue to vary significantly in their transfusion practices for CABG surgery. A more rational and conservative approach to transfusion practice at the institutional level is warranted.

Blood Component Transfusion↗
PubMed1998

Angiographic and histological evaluation of porcine retinal vascular damage and protection with perfluorocarbons after massive air embolism.

BACKGROUND AND PURPOSE: We have previously shown that perfluorocarbon emulsions (PFEs) reduce the severity of cerebral injury (indicated by infarct, reduced blood flow, and depressed EEG) induced by air embolism during cardiopulmonary bypass (CPB). This study used retinal fluorescein angiography to define the mechanisms of cerebral injury and to determine the efficacy of PFEs in cerebral protection. These angiographic findings were correlated to previously reported histologic findings. METHODS: Twenty domestic pigs underwent CPB with a prime of standard crystalloid or PFE (5 mg/kg) and crystalloid. After 10 minutes on CPB, a single (5 mL/kg) or double (2x2.5 mL/kg) bolus of room air or saline (control) was delivered via the right carotid artery. Retinal fluorescein angiograms were captured at 4 time points: baseline, air insult, postbypass, and postreperfusion. Following euthanasia, both eyes were removed and the retinas isolated for histological analysis with horseradish peroxidase (HRP), as previously reported. RESULTS: In control pigs, postreperfusion angiograms showed small nonperfused areas, and retinal whole mounts demonstrated vascular damage as previously reported. In 5 PFE-primed animals, postreperfusion angiograms showed hyperfluorescence, but angiograms and HRP mounts were otherwise not significantly different from baseline. Severely hyperfluorescent vessels observed angiographically also showed a correlation with HRP extravasation but were not consistently indicative of severe vascular damage. CONCLUSIONS: Retinal fluorescein angiography and retinal staining with HRP indicate that mechanisms of cerebral air embolism include nonperfusion, vascular leakage and spasm, red blood cell sludging, and hemorrhage. Priming with PFE prevented many of the sequelae associated with air embolism.

Animals↗
PubMed1997

Perfluorocarbon emulsion in the cardiopulmonary bypass prime reduces neurologic injury.

BACKGROUND: Perfluorocarbon emulsion has proved beneficial in the prevention and amelioration of experimental air embolism. We examined whether the addition of perfluorocarbon to the prime solution could lead to a reduction in the incidence and severity of neurologic injury after the formation of a massive air embolism during cardiopulmonary bypass. METHODS: Fourteen pigs underwent bypass in which either a crystalloid prime solution or a perfluorocarbon prime solution (10 mL/kg) was used. Ten minutes into bypass a bolus (5 mL/kg) of air or saline (control) was delivered via the carotid artery. The resulting cerebral infarcts were graded on the basis of the findings in triphenyltetrazolium chloride-stained cerebral sections. Colored microspheres were used to measure cerebral blood flow. Bitemporal electroencephalography was used to evaluate cerebral function. RESULTS: Cerebral infarction was not found in the perfluorocarbon-air group (0 to 5 animals), as compared with its occurrence in 3 of the 5 animals in the crystalloid-air group. Cerebral blood flow was also maintained or increased in the perfluorocarbon-air group (p < 0.05), and the electroencephalogram total power showed less of a decrease and recovered more completely (p < 0.05) than it did in the crystalloid-air group. CONCLUSIONS: The addition of perfluorocarbon emulsion to the cardiopulmonary bypass prime solution leads to a reduction in the incidence and severity of neurologic injury after the formation of a massive air embolism during bypass.

Animals↗
PubMed1997

Horseradish peroxidase as a histological indicator of mechanisms of porcine retinal vascular damage and protection with perfluorocarbons after massive air embolism.

BACKGROUND AND PURPOSE: This laboratory has previously shown that a second-generation perfluorocarbon emulsion (PFE) reduces the severity of cerebral injury induced by air embolism during cardiopulmonary bypass (CPB). Horseradish peroxidase examines vascular permeability and was used in this study of the mechanisms of cellular protection afforded by the PFE. METHODS: Twenty domestic pigs underwent CPB with a prime of standard crystalloid or PFE (5 mg/kg) and crystalloid. After 10 minutes on CPB, a 5-mL/kg bolus of room air or saline (control) was delivered via the right carotid artery. The air insult was delivered as either a single bolus or double bolus. After 1 hour of CPB and 1 hour of spontaneous reperfusion, horseradish peroxidase was injected intravenously and circulated for 15 minutes. After euthanasia, both eyes were removed, and the retinas were isolated for histological analysis. RESULTS: Total length of retinal vessels exhibiting horseradish peroxidase extravasation was significantly less in PFE pigs (P < .05). Vascular spasm and red blood cell hemorrhages were unaffected by PFE. PFE pigs exhibited mild to moderate vascular nonperfusion and red blood cell sludging; crystalloid groups demonstrated severe nonperfusion and sludging. CONCLUSIONS: Histological staining with horseradish peroxidase indicated that mechanisms of cerebral air embolism include vascular endothelial leakage, vascular nonperfusion, and red blood cell sludging and hemorrhage. Pretreatment with PFE prevented some sequelae associated with massive air embolism and CPB.

Animals↗
PubMed1997

A comparison of thromboelastography with heparinase or protamine sulfate added in vitro during heparinized cardiopulmonary bypass.

Thromboelastography (TEG) has been used after cardiopulmonary bypass (CPB) to diagnose excessive postoperative hemorrhage. Conventional TEG during CPB is not possible due to the sensitivity of the TEG to even small amounts of heparin, which produces a nondiagnostic tracing. The purpose of this study was to compare heparin neutralization using heparinase or protamine in TEG blood samples obtained during CPB. TEG testing was performed on 48 patients before, during and after CPB. Tissue plasminogen activator activity and antigen were measured on a subset of 32 patients. We found: 1) heparinase neutralized at least 10 IU/ml heparin while 1.6 ug/ml protamine neutralized up to 7 IU/ml heparin, 2) in samples with complete heparin neutralization by both methods, there was no significant difference in the R values, 3) while there was good correlation for other TEG parameters between heparinase and protamine treated samples, heparinase treatment produced shorter K values and higher angle, MA and A60, 4) while fibrinolysis was detected using both methods, heparinase treatment suppressed fibrinolysis in the TEG in both samples from patients and after in vitro addition of tissue plasminogen activator, 5) TEG was not a sensitive indicator of t-PA activity, detecting only 21% of samples with increased t-PA activity during bypass, and 5) heparinase was at least 100 times more expensive than protamine. We conclude that while both heparinase and protamine can be used to neutralize heparin in TEG samples obtained during CPB, protamine neutralization is more sensitive to fibrinolysis and less expensive, but the protamine dose must be carefully selected to match the heparin level used at individual institutions.

Adult↗
PubMed1996

Endothelial cell injury in cardiovascular surgery: the procoagulant response.

The vascular endothelium plays a critical role in the regulation of coagulation through the constitutive expression and release of anticoagulants and the inducible expression of procoagulant substances. Cardiopulmonary bypass dysregulates this process by activating endothelial cells, initially promoting bleeding and then thrombosis. Endothelial cell activation in response to circulating inflammatory mediators leads to the initiation of coagulation when tissue factor is expressed throughout the intravascular space. This results in the widespread consumption of coagulation factors. Additionally, there is a cardiopulmonary bypass-related qualitative platelet defect that is exacerbated by thrombocytopenia as platelets are consumed from the circulation by clot and adherence to the cardiopulmonary bypass circuit. Finally, cardiopulmonary bypass results in the endothelial release of plasminogen activators, which lead to an increase in systemic fibrinolysis. The diffuse generation of thrombin, driven by the inducible intravascular expression of tissue factor, plays a major role in all of these processes. Efforts to understand the critical role of the endothelium in coagulation may lead to novel therapies to prevent bleeding or thrombosis in cardiovascular surgery patients.

Blood Coagulation↗
PubMed1996

The agreement between ventricular volumes and ejection fraction by transesophageal echocardiography or a combined radionuclear and thermodilution technique in patients after coronary artery surgery.

OBJECTIVES: To study the reproducibility of and agreement between perioperative transesophageal echocardiographic (TEE) and radionuclide (RN) assessment of ventricular volumes and ejection fraction (EF). DESIGN: A prospective, blinded comparison of two methods of measurement. SETTING: A surgical intensive care unit in a university hospital. PARTICIPANTS: Patients after coronary artery bypass surgery. INTERVENTIONS: Left ventricular volumes and ejection fraction were simultaneously measured by radionuclide ventriculography and transesophageal echocardiography. Two sets of measurements were made in rapid succession with a third set after an interval. RESULTS: Reproducibilities of EF and ventricular volumes by TEE and RN were similar. At each set of measurements, the bias for radionuclide EF and TEE Simpson's rule EF, 0.03 +/- 0.05, 0 +/- 0.06, -0.01 +/- 0.07, respectively, for radionuclide EF and TEE area length EF 0.01 +/- 0.05, -0.01 +/- 0.05, -0.03 +/- 0.08, respectively, were significantly less than for radionuclide EF and TEE FAC 0.07 +/- 0.05, 0.05 +/- 0.05, 0.03 +/- 0.09. Poor agreement was observed between RNTD-EDV, and both of the TEE EDV measurements. CONCLUSION: EF measured by TEE area length and Simpson's rule method are as reproducible as TEE FAC and are more accurate estimates of RN EF. Poor agreement between methods of measuring end-diastolic volume was observed.

Aged↗
PubMed1996

Perfluorocarbon emulsions and cardiopulmonary bypass: a technique for the future.

Artificial blood has been sought for a considerable period of time and two major lines of research have led to FDA testing of some possible compounds. The two major types of compounds are polymerized hemoglobin moieties and perfluorocarbon emulsions (PFC). Polymerized hemoglobin preparations have the ability to carry oxygen and release it in a manner similar to the oxyhemoglobin dissociation curve of whole blood. PFCs carry oxygen, nitrogen and carbon dioxide, as well as all other non-polar gases, by enhanced chemical solubility. Therefore, all dissolved gases are available for metabolic utilization and no sinusoidal release curve of oxygen is encountered. Early PFC emulsions had problems with toxicity of the emulsifier and were difficult to get into their emulsion for infusion. Furthermore they were very dilute in the active ingredient for gas transport. Today there are second generation PFCs becoming available that have a 40% concentration of the PFC and therefore the potential for gas transport is greatly increased. The PFC emulsions have a very small size, 0.1 microns, so the surface for gas exchange is massively increased as well as the potential increased for perfusion into areas of potentially sludged erythrocytes. Work with the PFCs has shown them now to be able to carry adequate oxygen to work as blood substitutes. They have shown protection from air embolism in a number of animal and end-organ models. What makes the PFCs unique is their ability to carry/absorb nitrogen and therefore protect from gas embolization. There are data in animal models showing significant cerebral protection in cardiopulmonary bypass models. The new PFCs should sometime in the not-too-distant future be tested in human bypass with assessments of neuropsychiatric dysfunction and stroke.

Animals↗