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Ian J Welsby

Publications and source records attributed to Ian J Welsby.

15 recordsLinked to original sources
PubMed2006

The kaolin-activated Thrombelastograph predicts bleeding after cardiac surgery.

OBJECTIVE: The objective of this study was to determine the relationship of the kaolin-activated Thrombelastograph (TEG) with postoperative bleeding and laboratory tests of coagulation in the setting of cardiac surgery with the routine use of -aminocaproic acid. DESIGN: Prospective observational study. SETTING: An adult heart center at a tertiary referral, university hospital. PARTICIPANTS: Thirty adult cardiac surgical patients. INTERVENTIONS: The kaolin-activated TEG, platelet counts, prothrombin times, activated partial thromboplastin times, and fibrinogen levels were measured before induction of anesthesia, during cardiopulmonary bypass, and on arrival in the intensive care unit. Mediastinal and thoracostomy drainage were measured every hour for 4 hours after arrival in the intensive care unit. MEASUREMENTS AND MAIN RESULTS: Correlation and multivariate linear regression modeling were used to describe relationships among coagulation tests, TEG parameters, and early postoperative bleeding. The TEG maximum amplitude (MA) parameter correlated well with postoperative bleeding (r = -0.6, p = 0.0018), more so than platelet count (r = -0.45, p = 0.02), fibrinogen level (r = -0.40, p = 0.06), or prothrombin time (r = 0.43, p = 0.02). The receiver operating characteristic curve c-index describing MA as a predictor for postoperative bleeding is 0.78. Abnormalities in all the laboratory test results were associated with an abnormal MA. CONCLUSIONS: In conclusion, the kaolin-activated TEG is associated with early coagulopathic bleeding. It may reflect the severity of a global coagulopathy affecting both platelets and coagulation factors and be a guide to incremental prohemostatic therapy in this setting.

Aged↗
PubMed2006

Genetics of coagulation: considerations for cardiac surgery.

Genetic variants in the coagulation system have been known since antiquity. Today, because of modern improvements in diagnosis and medical management, the clinician is likely to encounter a spectrum of coagulation factor deficiencies and identified polymorphic variants in the surgical population. Because perioperative hemorrhagic and thrombotic complications are potentially serious, it is important to understand the role that these defects and variants may play in predicting risk and optimizing patient management. The implications of coagulation genetics on the perioperative management of the cardiac surgery patient are reviewed.

Blood Coagulation Disorders, Inherited↗
PubMed2006

Thromboelastography detects inadequate response to abciximab therapy during stent-assisted cerebral aneurysm coil embolization complicated by stroke.

INTRODUCTION: Thromboembolic stroke is the most common severe complication following coil embolization of intracerebral aneurysms, with a 5% incidence of permanent deficits. Despite heparin anticoagulation, rescue therapy with the platelet glycoprotein IIb/IIIa receptor antagonist abciximab may be required. However, we describe a failure of abciximab rescue therapy and discuss the importance of monitoring the variable individual response to abciximab. CASE REPORTS: Two patients underwent stent-assisted cerebral aneurysm coil embolization complicated by thromboembolic stroke. In one patient, abciximab rescue therapy failed and was associated with a poor neurological outcome. Thromboelastography (TEG model 5000; Haemoscope, Skokie, IL) and platelet aggregometry suggested inadequate platelet inhibition, although other tests of platelet function suggested adequate inhibition. CONCLUSION: We describe a failure of regular-dose abciximab rescue therapy for thromboembolic stroke-complicating stent-assisted cerebral aneurysm coil embolization. The use of TEG to individualize abciximab dosing in this setting may improve patient outcome, as it tracks a pattern of coagulation consistent with the clinical picture.

Abciximab↗
PubMed2005

Changing systems for measuring activated clotting times: impact on the clinical practice of heparin anticoagulation during cardiac surgery.

BACKGROUND: The activated clotting time (ACT) is a standard monitor for heparin anticoagulation during cardiopulmonary bypass (CPB). This study determines the effect of upgrading our ACT system on our clinical practice with regards to the conduct and safety of heparin anticoagulation during cardiopulmonary bypass. METHODS: We compared the intraoperative heparin doses required for all adult cardiac surgery patients (n=1240) and postoperative bleeding for a subset of primary aortocoronary bypass (CABG) surgery procedures (n=285) from cohorts before and after the change in ACT systems. RESULTS: The heparin dose needed to exceed our target ACT of 480 sec for the duration of CPB was higher (45000 vs. 40000 units; p<0.0001), and the mean ACT during CPB was lower (557 vs. 618 sec; p<0.05) using the new ACT system. Furthermore, this coincided with decreased postoperative bleeding in the CABG subset (median value of 417 vs. 575 ml over 12 h; p<0.0005). CONCLUSIONS: We demonstrated that the introduction of the Actalyke ACT system significantly altered our clinical practice by increasing the heparin dose required to exceed our target ACT during CPB. Prospective study to determine the effect of Actalyke ACT system monitoring on hemostasis after cardiac surgery is merited.

Adult↗
PubMed2005

Preoperative anti-PF4/heparin antibody level predicts adverse outcome after cardiac surgery.

OBJECTIVE: Preexisting serum antibodies to heparin/platelet factor 4 complexes may predispose adult cardiac surgical patients to increased perioperative morbidity and mortality. We sought to determine the association between preoperative serum antibodies directed against platelet factor 4/heparin complexes and major complications (in-hospital death or length of stay >10 days) in adult cardiac surgical patients. METHODS: In a prospective observational study of 466 patients undergoing elective coronary artery bypass grafting, valvular heart surgery, or both, preoperative serum was assayed for anti-platelet factor 4/heparin antibody by using a commercially available enzyme-linked immunosorbent assay (Asserachrom HPIA). Known preoperative risk factors were assessed, and patients were assigned a risk score by using the validated method of Parsonnet and colleagues. RESULTS: Major complications (death or postoperative hospitalization >10 days) occurred in 108 patients (23%). Overall, 59 (13%) patients had a positive preoperative anti-platelet factor 4/heparin antibody screen (upper limit of normal is 0.5 optical density units). A positive assay result independently predicted an increased risk of major complications (P = .0284; odds ratio, 1.98; 95% confidence interval, 1.06-3.62) over and above the effect of the Parsonnet risk score (P < .001; odds ratio, 1.07; 95% confidence interval, 1.05-1.10). The level of preoperative anti-platelet factor 4/heparin antibody was also significantly associated with major complications (P = .036; odds ratio, 1.31; 95% confidence interval, 1.02-1.68) independently of the Parsonnet risk score. No association (P > .75) existed between the Parsonnet risk score and preoperative anti-platelet factor 4/heparin antibody level. CONCLUSIONS: Serum antibodies directed against platelet factor 4/heparin complexes are prevalent in the adult patient population undergoing cardiac surgery. The presence of these antibodies before surgery is an independent predictor for death or prolonged hospitalization after adult cardiac surgery.

Aged↗
PubMed2005

Infectious complications after cardiac surgery: lack of association with fresh frozen plasma or platelet transfusions.

OBJECTIVE: The purpose of this study was to examine the effect of perioperative transfusion of platelets and fresh frozen plasma (FFP) on infection rates after cardiac surgery. DESIGN: Retrospective study comparing infection rates after cardiac surgery among patients receiving combinations of packed red blood cells (PRBCs), platelets, and FFP. SETTING: Tertiary care university teaching hospital. PARTICIPANTS: All elective primary coronary artery bypass (CABG) surgery patients from July 1995 to January 1998 before introduction of leukocyte-reduced blood products. INTERVENTIONS: Multivariate logistic and linear regression models were applied to identify clinical risk factors for postoperative infection and to determine the relationship between perioperative administration of PRBCs, platelets, and FFP with postoperative infection. MEASUREMENTS AND MAIN RESULTS: Transfusion of PRBCs, diabetes, age, preoperative hematocrit, and the duration of cardiopulmonary bypass were significantly associated with postoperative infection; platelet or FFP transfusion added no additional risk to PRBC transfusion alone. CONCLUSIONS: Infectious complications in a population of adult primary CABG surgery patients were not increased by transfusion of platelets or FFP. It is PRBC transfusion that confers an increased risk of postoperative infection in this population.

Bacterial Infections↗
PubMed2005

Hemodynamic changes after protamine administration: association with mortality after coronary artery bypass surgery.

BACKGROUND: Protamine sulfate is standard therapy to reverse heparin anticoagulation. Hemodynamic responses to protamine are common, ranging from minor perturbations to cardiovascular collapse. Although severe fatal reactions occur, the relation of less extreme responses with postoperative mortality is unknown. Therefore, the authors tested the hypothesis that hemodynamic "protamine reactions" (systemic hypotension and pulmonary hypertension) are associated with mortality after cardiac surgery. METHODS: In a university hospital setting, the authors studied 6,921 coronary bypass patients using automated anesthesia record-keeping data and quality assurance databases. Degree/duration integrals of systemic hypotension (< 100 mmHg) and pulmonary hypertension (> 30 mmHg) for the 30-min after protamine administration were assessed for linear associations with mortality using multiple logistic regression models adjusting for risk factors. RESULTS: Overall mortality was 2%; greater hemodynamic responses were associated with increased mortality by odds ratios of 1.28 (systemic hypotension: 95% confidence interval, 1.14-1.43; P < 0.001) and 1.27 (pulmonary hypertension: 95% confidence interval, 1.06-1.48; P < 0.001) per 150-mmHg . min increment. Proximity of the response to protamine administration strengthened the relation, which persisted after exclusion of major hemodynamic disturbances. Tests for linearity confirmed an association even at the lowest range of values for both pressure effects. CONCLUSIONS: Hemodynamic perturbations after protamine administration are independently related to in-hospital mortality after primary coronary artery bypass surgery; the relation is present even in the lowest observed range of values for both systemic hypotension and pulmonary hypertension. Although randomized trials are necessary to address causality, this evidence suggests that strategies that avoid or attenuate these reactions may improve patient care.

Aged↗
PubMed2005

Efficacy and safety of heparinase I versus protamine in patients undergoing coronary artery bypass grafting with and without cardiopulmonary bypass.

BACKGROUND: Hemodynamic protamine reactions with heparin reversal during cardiac surgery are common and associated with adverse outcomes. As an alternative to protamine, the authors examined heparinase I reversal of heparin after aortocoronary bypass graft surgery. METHODS: In a randomized, double-blind, double-dummy trial, 167 on- and off-pump aortocoronary bypass graft surgery patients received either heparinase I (maximum 35 microg/kg) or protamine (maximum 650 mg) for heparin reversal, monitored by activated clotting time values and clinical assessment. Hemodynamic parameters were recorded electronically; safety evaluation was to 30 days postoperatively. Noninferiority was predefined as 400 ml or less median 12-h chest tube drainage from intensive care unit arrival for heparinase I patients, after risk adjustment. Hemodynamic instability was defined as systemic hypotension (> or = 30 mmHg decrease) and/or pulmonary hypertension (> or = 40 mmHg with an increase > or = 10 mmHg) within 30 min of heparin reversal initiation. RESULTS: Patient enrollment was terminated on advisement of the Data Safety Monitoring Board. Although heparinase I was noninferior for 12-h chest tube drainage, protamine had a superior safety profile. Overall, heparinase I subjects had longer hospital stays (P = 0.04), were more likely to experience a serious adverse event (P = 0.01), and were less likely to avoid transfusion (P = 0.006). A composite morbidity score was not different (P = 0.24), and similar rates of hemodynamic instability were observed between groups. Findings were consistent in analyses stratified by on- and off-pump surgery. CONCLUSIONS: Heparinase I reverses heparin anticoagulation after aortocoronary bypass graft surgery but is not equivalent to protamine because of its inferior safety profile.

Adolescent↗
PubMed2002

Activated clotting time systems vary in precision and bias and are not interchangeable when following heparin management protocols during cardiopulmonary bypass.

OBJECTIVE: Our aim was to test the hypothesis that new activated clotting time (ACT) technology, with modifications to instruments and reagents designed to detect earlier clot formation, would be associated with more precise but lower results. A secondary objective was to evaluate the potential impact of any change in ACT measurement on heparin requirements during cardiopulmonary bypass (CPB). METHODS: We compared the precision of two newer ACT systems: Actalyke, Helena Laboratories, Beaumont, TX and Hemochron Response, International Technidyne Corporation, Edison, NJ and assessed their bias with reference to a standard ACT system (Hemochron 801, International Technidyne Corporation, Edison, NJ). Bland-Altman analysis was applied to 81 duplicate samples from 22 patients undergoing CPB or percutaneous coronary interventions (PCI), covering the full clinical range of ACT values. We also estimated the change in heparin dose required to use the Actalyke rather than the Hemochron 801 results, to achieve our target ACT for CPB (480 seconds), and used a mixed model to test for significance. RESULTS: The precision of the Actalyke was superior to the Hemochron Response (mean difference of duplicates +/- 0.1% versus +/- 4.2%). There was no significant bias (p = 0.93) between the results from the standard analyzers (Hemochron 801 and Response), but the results from the modified system (Actalyke) were on average 18% lower than the Hemochron 801 (p < 0.0001). Estimated heparin requirements established that fifty percent of CPB patients would have required additional heparin (5000 to 17500 units), an average increase of 1060 units per patient (p = 0.05), if the Actalyke values were used to guide anticoagulation during CPB. CONCLUSIONS: Our results support the hypothesis that the modified technology (Actalyke) is associated with more precise but lower ACT results. We estimated these lower values would lead to increased heparin dosing during CPB. The impact of this increase on bleeding after cardiac surgery with CPB is controversial and requires further study.

Adult↗
PubMed2002

The association of complication type with mortality and prolonged stay after cardiac surgery with cardiopulmonary bypass.

UNLABELLED: Outcome after cardiac surgery varies depending on complication type. We therefore sought to determine the association between complication type, mortality, and length of stay in a large series of patients undergoing cardiac surgery with cardiopulmonary bypass (CPB). Multivariate logistic regression was used to test for differences between complication types in mortality and prolonged length of stay (>10 days) while controlling for preoperative and intraoperative risk factors. In 2609 consecutive cardiac surgical patients requiring CPB, the mortality rate was 3.6%; 36.5% had one or more complications, and 15.7% experienced an adverse outcome (death or prolonged length of stay). Multivariate logistic regression demonstrated that complication type was significantly associated with adverse outcome (P < 0.001) independent of Parsonnet score and CPB time (c-index = 0.80). The development of noncardiac complications only (Group NC) and cardiac complications with other organ involvement (Group B) significantly increased mortality and hospital and intensive care unit length of stay (P < 0.001) when compared with cardiac complications only (Group C). The incidences of adverse outcome in Groups C, NC, and B were 15%, 43%, and 67%, respectively; the mortality rates were 3%, 7%, and 20%, respectively. All these intergroup comparisons were significantly different (adjusted P < 0.05). Complications involving organs other than the heart appear to be more deleterious than cardiac complications alone, underscoring the need for strategies to reduce noncardiac complications. IMPLICATIONS: Complications, particularly when they involve organs other than just the heart, increase mortality and prolong the length of hospital stay after heart surgery, independent of a patient's preoperative risk factors and the duration of cardiopulmonary bypass. Strategies aimed at preventing damage to other organs during cardiac surgery need to be improved.

Adult↗