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Biomedical subjects

M Bigham

Publications and source records attributed to M Bigham.

16 recordsLinked to original sources
PubMed2001

The relationship between hirudin and activated clotting time: implications for patients with heparin-induced thrombocytopenia undergoing cardiac surgery.

UNLABELLED: Anticoagulation with recombinant hirudin (r-hirudin) (Refludan) has been suggested as an alternative to heparin for patients with heparin-induced thrombocytopenia requiring cardiac surgery. We sought to develop a modified activated coagulation time (ACT) that would allow quantification of the levels of r-hirudin required during cardiopulmonary bypass (CPB). Twenty-one patients scheduled for elective cardiac surgical procedures requiring CPB were enrolled in this IRB-approved study. R-hirudin was added to blood specimens obtained before heparin administration (before CPB) and 30 min after heparin neutralization with protamine (after CPB) to result in concentrations of 0, 2, 4, 6, 7, or 8 microg/mL. Kaolin/ACT and complete blood count measurements were assayed in native specimens (first 10 patients, Phase I) or in specimens mixed with equal volumes of commercial normal plasma (second 11 patients, Phase II). In Phase I, good (r(2) = 0.83) linear relationships between ACT values and r-hirudin concentrations (< or =4 microg/mL) were observed in specimens obtained before CPB. However, ACT values were markedly prolonged (P < 0.0001) by r-hirudin in specimens obtained after CPB, with ACT values generally exceeding the ACT's detection limit (>999 s) at hirudin concentrations >2 microg/mL. In patient specimens mixed with normal plasma (Phase II), ACT/hirudin relationships (i.e., hirudin/ACT slope values obtained with hirudin concentration < or =4 microg/mL) in the post-CPB period (0.022 +/- 0.004 microg. mL(-1). s(-1)) were similar (P = 0.47) to those (0.019 +/- 0.004 microg. mL(-1). s(-1)) obtained in the pre-CPB period. Accordingly, a significant relationship between normal plasma-supplemented ACT values and predilution hirudin concentration was obtained in the post-CPB (hirudin = 0.039ACT - 4.34, r(2) = 0.91) period. Although our data demonstrate that the ACT test cannot be used to monitor hirudin during CPB, the addition of 50% normal plasma to post-CPB hemodiluted blood specimens yields a consistent linear relationship between hirudin concentration and ACT values up to a predilution concentration of 8 microg/mL. Plasma-modified ACT may be useful in monitoring hirudin anticoagulation during CPB. IMPLICATIONS: A modified activated clotting time test system that may be helpful in monitoring hirudin anticoagulation in patients with heparin-induced thrombocytopenia during cardiac surgery with cardiopulmonary bypass is described.

Anticoagulants↗
PubMed2000

The effect of epsilon-aminocaproic acid on HemoSTATUS and kaolin-activated clotting time measurements.

UNLABELLED: New point-of-care assays have been used to identify patients with heparin resistance (i.e. heparin dose response test; Medtronic Blood Management, Parker, CO) and who have platelet dysfunction (i.e. HemoSTATUS; Medtronic Blood Management). We examined the effect of epsilon-aminocaproic acid on results from these two point-of-care tests in patients undergoing cardiac surgery. Twenty patients scheduled for elective cardiac surgical procedures were enrolled in this prospective study. HemoSTATUS clot ratio (% maximal) values in Channels (Ch) 3-6 (Ch 3: 26 +/- 25, Ch 4: 66 +/- 23, Ch 5: 84 +/- 20, Ch 6: 106 +/- 18) obtained after the IV administration of epsilon-aminocaproic acid were similar to values obtained before the administration of this agent (Ch 3: 26 +/- 20, Ch 4: 69 +/- 23, Ch 5: 86 +/- 19, Ch 6: 109 +/- 14). Slope values (86 +/- 23 s x U(-1) x mL(-1)) and projected heparin concentrations (4 +/- 1 U/mL) obtained before the administration of epsilon-aminocaproic acid were similar to slope values (88 +/- 21 s x U(-1) x mL(-1)) and projected heparin concentrations (4 +/- 1 U/mL) values obtained after administration of this agent. Our data indicate that HemoSTATUS clot ratio values and heparin dose response values are not significantly affected after IV dosing of epsilon-aminocaproic acid. IMPLICATIONS: Values from two activated coagulation time-based test systems used to identify significant heparin resistance or platelet dysfunction after cardiopulmonary bypass were not significantly affected by epsilon-aminocaproic acid administered IV.

Aged↗
PubMed2000

Clinical evaluation of a new, point-of-care hemocytometer.

OBJECTIVE: This study was designed to compare results obtained with a new point-of-care hemocytometer with those of two established (point-of-care and laboratory-based) instruments. DESIGN: To compare CBC values between established laboratory-based and point-of-care instruments, measurements were performed on routinely obtained blood specimens for CBC analysis in our institutional laboratory (phase I) and on specimens from cardiac surgical patients before initiation of cardiopulmonary bypass and after discontinuation of cardiopulmonary bypass in phase II. SETTING: Surgical and hospitalized patients at a tertiary care center. PATIENTS: Measurements were obtained by using blood specimens obtained from 141 hospitalized patients from different services (phase I) or from a consecutive series of 204 patients undergoing cardiac operations (phase II). MEASUREMENTS AND MAIN RESULTS: Hemoglobin (HGB), platelet count (PLT), red blood cell count, and white blood cell count (WBC) were measured with two on-site and one laboratory-based instruments. Hematocrit (HCT) was calculated by using measured variables. Linear regression demonstrated good correlations between Ichor and T540 HGB (r2 = .95), HCT (r2 = .95), PLT (r2 = .94), and WBC (r2 = .95) results (n = 408); similarly, good correlations were observed with Coulter STKS HGB (r2 = .92), HCT (r2 = .91), and PLT (r2 = .94) results (n = 141). The relationship between Ichor and Coulter STKS WBC (r2 = .27) was poor; however, when two Ichor-derived outlier values (>50) were excluded, the relationship was very good (r2 = .99). Bias analysis (mean +/- SD) demonstrated similar results between Ichor and T540 HGB (0.003+/-0.5), HCT (-0.21+/-1.5), WBC (0.79+/-1.3), and PLT values (-9.2+/-16.6) as well as STKS HGB (-0.08+/-0.7), HCT (-0.69+/-2.3), WBC (-0.62+/-5.8), and PLT values (-10.2+/-21.4). CONCLUSIONS: The Ichor hemocytometer provides accurate hematologic results that can facilitate rapid quantitative assessment of CBC variables and thus may be clinically useful, especially in critically ill patients.

Bias↗
PubMed1998

Relation between hospital HIV/AIDS caseload and mortality among persons with HIV/AIDS in Canada.

OBJECTIVE: To assess the relation between HIV/AIDS hospital caseload and mortality in Canada. DESIGN: Descriptive, population-based study. SETTING: All hospitals in Canada that admitted any patients with HIV or AIDS between Mar. 31, 1987, and Apr. 1, 1994. PATIENTS: All patients with a diagnostic code on their hospital discharge abstract for HIV infection, AIDS, or with positive serological or viral culture findings for HIV (International Classification of Diseases, 9th revision, 042, 043, 044 or 795.8). MAIN OUTCOME MEASURE: In-hospital mortality. RESULTS: Over the study period, 38,075 admissions attributed to HIV/AIDS (33,380 of men and 4695 of women) were recorded in 513 Canadian hospitals. Of these hospitals, 230 (45%) had fewer than 1 admission per year of patients with HIV/AIDS; 200 (39%) had between 1 and 9; 68 (13%) had between 10 and 99; and 15 (3%) had 100 or more. HIV/AIDS-related admissions ending in death were independently associated with the patient being admitted to lower-volume hospitals, being hospitalized for longer periods of time, and being older, male and at a more advanced stage of disease. During the study period, hospitals with 100 or more admissions per year reported 36% lower mortality among patients with HIV/AIDS than those that had fewer than 1 admission per year. CONCLUSION: There is an inverse relation between hospital caseload and in-hospital mortality among patients with HIV/AIDS in Canada. We attribute this association at least in part to the propensity of high-volume hospitals to deal more effectively with seriously ill patients with HIV/AIDS.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

An outbreak of mumps among young adults in Vancouver, British Columbia, associated with 'rave' parties.

UNLABELLED: In early 1997 an unexpectedly high number of cases of mumps was reported in Vancouver, British Columbia. METHODS: A case control study was conducted to address four objectives: 1) Describe the outbreak and the population at risk, 2) examine the impact of mumps on this population, 3) identify personal risk factors for infection, and 4) test the hypothesis that social gatherings, 'rave' parties in particular, were a risk factor in this outbreak. RESULTS: Mumps infection was associated with: attending a rave party [OR = 17; 95% CI: 2.7-710], residing in Vancouver [OR = 3.7; 95% CI: 1.4-10], and contact with a person with mumps [OR = 13; 95% CI: 2-552], during the 'exposure' period. Vaccine effectiveness, ascertained by self-reported immunization status, was 80% [95% CI: 29%-96%]. CONCLUSIONS: Attendance at rave parties was associated with mumps infection during this outbreak. Many persons aged 17-40 may remain susceptible to mumps; in BC these persons are eligible for one dose of MMR and should be encouraged to be vaccinated.

Adolescent↗
PubMedDate not supplied

Public health and hepatitis C.

This paper reviews key public health aspects related to surveillance, transmission and primary prevention of hepatitis C. Hepatitis C is now a reportable disease in all Canadian provinces and territories. Although prevalence in Canada is estimated at under 1%, that associated with injection drug use (IDU) approaches 90%. The epidemiology of new HCV infections in Canada is now primarily defined by IDU behaviour, with annual incidence rates among new drug injectors exceeding 25%. HCV is less efficiently transmitted through other routes of exposure. An effective vaccine against HCV remains elusive. Some jurisdictions offer hepatitis A and hepatitis B vaccine to HCV-infected persons. An array of harm reduction strategies targeting IDU has been implemented but underdeployed across Canada, and has been ineffective to date in controlling the HCV epidemic. Public policy alternatives, such as legalization and regulation of injection drugs, are being debated. Improved HCV preventive strategies are urgently required and need careful evaluation.

Canada↗
PubMedDate not supplied

Comparing benefits and risks of immunization.

BACKGROUND: This paper uses a straightforward method of quantifying the benefits and risks of immunization, illustrated by universal immunization programs in British Columbia against invasive Haemophilus influenzae type b disease (Hib), measles, rubella, and paralytic poliomyelitis. METHODS: Data were extracted from provincial communicable disease and vaccine adverse event surveillance systems. Average disease incidence was compared before and after implementing universal immunization programs. Estimates of prevented deaths and serious disease complications were calculated and compared with expected numbers of serious vaccine-associated adverse events (VAAEs). RESULTS: Average incidence of reported cases decreased 90 to 100% over a 5-year period after implementing universal programs. These benefits were sustained or strengthened over time. Rates of reported serious VAAEs were low. DISCUSSION: The remarkable success of immunization has created a paradox. Despite a low absolute risk of serious VAAEs, the relative risk of some VAAEs can exceed risk of disease in the province.

British Columbia↗
PubMedDate not supplied

Uptake and behavioural and attitudinal determinants of immunization in an expanded routine infant hepatitis B vaccination program in British Columbia.

INTRODUCTION: British Columbia (BC) implemented a universal infant hepatitis B (HB) immunization program in 2001. The study objective was to evaluate HB immunization coverage among the first six-month cohort of eligible infants in the province outside of the Vancouver-Richmond health region and to assess parent/guardian behavioural and attitudinal determinants of HB immunization. METHODS: A cross-sectional survey of HB immunization was conducted using a random sample of eligible infants born between 1 January-30 June 2001. HB immunization coverage data were obtained from the provincial Public Health Information System, and through a telephone survey of 487 of eligible infants' parents/guardians that was conducted between October 2002-January 2003. At this time, parents/guardians were also asked about behaviours and attitudes towards immunization, based on the Immunization Health Belief Model Scale. RESULTS: HB immunization coverage with at least one dose of HB vaccine was 89% and uptake of 3 doses of HB vaccine was 78%. HB immunization was significantly associated (p<0.001) with a recommendation for HB immunization from a health care professional. The main reason for non-HB immunization was parental concern about side effects. DISCUSSION: Seventy-eight percent of infants completed the 3-dose HB vaccination schedule. Parental behaviour regarding HB immunization of their children was strongly influenced by a supportive recommendation from either a nurse or doctor.

Attitude to Health↗