PubMed Health⌕ Search

Biomedical subjects

P C Hebert

Publications and source records attributed to P C Hebert.

11 recordsLinked to original sources
PubMed2002

Transfusion thresholds and other strategies for guiding allogeneic red blood cell transfusion.

BACKGROUND: Most clinical practice guidelines recommend restrictive red cell transfusion practices with the goal of minimising exposure to allogeneic blood (from an unrelated donor). The purpose of this review is to compare clinical outcomes in patients randomised to restrictive versus liberal transfusion thresholds (triggers). OBJECTIVES: To examine the evidence on the effect of transfusion thresholds, on the use of allogeneic and/or autologous blood, and the evidence for any effect on clinical outcomes. SEARCH STRATEGY: Trials were identified by: computer searches of OVID Medline (1966 to December 2000), Current Contents (1993 to Week 48 2000), and the Cochrane Controlled Trials Register (2000 Issue 4). References in identified trials and review articles were checked and authors contacted to identify any additional studies. SELECTION CRITERIA: Controlled trials in which patients were randomised to an intervention group or to a control group. Trials were included where the intervention groups were assigned on the basis of a clear transfusion "trigger", described as a haemoglobin (Hb) or haematocrit (Hct) level below which a RBC transfusion was to be administered. DATA COLLECTION AND ANALYSIS: Trial quality was assessed using criteria proposed by Schulz et al. (1995). Relative risks of requiring allogeneic blood transfusion, transfused blood volumes and other clinical outcomes were pooled across trials using a random effects model. MAIN RESULTS: Ten trials were identified that reported outcomes for a total of 1780 patients. Restrictive transfusion strategies reduced the risk of receiving a red blood cell (RBC) transfusion by a relative 42% (RR=0.58: 95%CI=0.47,0.71). This equates to an average absolute risk reduction (ARR) of 40% (95%CI=24% to 56%). The volume of RBCs transfused was reduced on average by 0.93 units (95%CI=0.36,1.5 units). However, heterogeneity between these trials was statistically significant (p<0.00001) for these outcomes. Mortality, rates of cardiac events, morbidity, and length of hospital stay were unaffected. Trials were of poor methodological quality. REVIEWER'S CONCLUSIONS: The limited published evidence supports the use of restrictive transfusion triggers in patients who are free of serious cardiac disease. However, most of the data on clinical outcomes were generated by a single trial. The effects of conservative transfusion triggers on functional status, morbidity and mortality, particularly in patients with cardiac disease, need to be tested in further large clinical trials. In countries with inadequate screening of donor blood the data may constitute a stronger basis for avoiding transfusion with allogeneic red cells.

Erythrocyte Transfusion↗
PubMed2000

Multiple combination bactericidal antibiotic testing for patients with cystic fibrosis infected with multiresistant strains of Pseudomonas aeruginosa.

We developed a rapid in vitro antibiotic susceptibility test to screen double- and triple-antibiotic combinations for bactericidal activity against 75 multiresistant Pseudomonas aeruginosa isolates referred from 44 cystic fibrosis (CF) patients. When used alone, the most effective intravenous antibiotic, meropenem, was bactericidal against only 44% of the isolates. High-dose tobramycin (200 microg/ml; concentrations achievable by aerosol administration) was bactericidal against 72% of isolates. Adding a second antibiotic significantly improved bactericidal activity. The most effective double-antibiotic combinations contained high-dose tobramycin plus meropenem, piperacillin/tazobactam, or ciprofloxacin, and were bactericidal against 88 to 94% of the isolates. Excluding high-dose tobramycin, the most effective intravenous double-antibiotic combinations contained meropenem plus ciprofloxacin, tobramycin (4 microg/ml), or cefipime, and were bactericidal against 85%, 71%, and 70% of isolates, respectively. Adding a third antibiotic did not significantly improve inhibition in vitro. We conclude that double-antibiotic combinations containing meropenem or high-dose tobramycin show the best bactericidal activity in vitro against multiresistant strains of P. aeruginosa. Addition of a third antibiotic to these double-antibiotic combinations may be unnecessary.

Aminoglycosides↗
PubMed1997

Differential performance of TRISS-like in early and late blunt trauma deaths.

OBJECTIVES: (1) To independently validate the Trauma and Injury Severity Score-Like (TRISS-Like) model derived by Offner et al. (Revision of TRISS for intubated patients. J Trauma. 1992;32:32-35) in a population of Canadian blunt trauma victims, and (2) to compare the ability of this model to predict mortality in early and late trauma deaths. STUDY POPULATION: Prospective cohort of blunt trauma cases with Injury Severity Score > 12 identified from the Ontario Trauma Registry over a 5-year period. STUDY DESIGN: The TRISS-Like model consisting of age, Injury Severity Score, systolic blood pressure, and best motor response of the Glasgow Coma Scale was evaluated as to its ability to predict mortality by determining the sensitivity, specificity, and the area under the receiver operating characteristic curve. The sample was then divided into early (< or = 7 days) and late mortality subgroups in which model performance was evaluated with respect to time of death. RESULTS: A total of 7,703 patients were included in this analysis. The overall mortality was 12.3%. The TRISS-Like model allowed for assessment of an additional 23% of patients than would standard TRISS and performed with a sensitivity of 97.1%, specificity of 39.8% and an area under the receiver operating characteristic curve of 0.873. Analysis of mortality with respect to time demonstrated that 75% of deaths occurred by day 7. The specificity and receiver operating characteristic area increased in the early (< or = 7 days) subgroup, 46.5% and 0.935, respectively, compared with 20.8% and 0.778 in the late mortality group. CONCLUSIONS: TRISS-Like demonstrated similar performance to that reported with the standard TRISS model but with the additional advantage that it is more generalizable because it can be applied to intubated patients. TRISS-Like demonstrated substantially superior performance in early trauma deaths compared with those that occurred late. This differential performance may be because the model does not include risk factors for late mortality.

Aged↗
PubMed1996

Validation of trauma and injury severity score in blunt trauma patients by using a Canadian trauma registry.

OBJECTIVE: To compare outcomes in blunt trauma by using Trauma and Injury Severity Score (TRISS) models derived from the Major Trauma Outcome Study (MTOS) and the Ontario Trauma Registry (OTR) as well as to evaluate the role of the Revised Trauma Score within the TRISS model. METHODS: Consecutive blunt trauma cases from 11 Level I trauma centers over a 4-year period were identified from the OTR. Coefficients of the Revised Trauma Score were modified using the Ontario data and this score was tested by using the Hosmer-Lemeshow Goodness of Fit Test. Two Ontario-specific TRISS models were developed with revised coefficients. The first used the standard Revised Trauma Score and the second used the Revised Trauma Score with regenerated coefficients. The accuracy of mortality predictions for all models were compared by using a Hosmer-Lemeshow Goodness of Fit procedure. Additionally, each TRISS models performance characteristics and receiver operating characteristic (ROC) curves were used to evaluate their discriminative capabilities. RESULTS: A total of 5,436 cases were incorporated in the analysis. Patients with all component TRISS variables had a significantly lower mortality compared to all blunt trauma patients (7.0% vs. 15.5%,p < 0.01). Use of the Revised Trauma Score led to the exclusion of 40% of cases because of absent data necessary to compute the score. The Hosmer-Lemeshow Goodness of Fit statistic for the Revised Trauma Score was 79.45 (p = 0.0001). The Hosmer-Lemeshow Goodness of Fit Statistic ranged from 11.42, p = 0.175 and 13.1, p = 0.125 for the Ontario TRISS models compared to 25.62, p < 0.005 for the MTOS TRISS model. Sensitivity of all three TRISS models ranged from 98% to 99% with specificity ranging from 24% to 35%. ROC curves were identical for all three TRISS models. CONCLUSIONS: TRISS demonstrated satisfactory performance in a Canadian blunt trauma population. Although revision of coefficients led to a better fit on the Hosmer-Lemeshow statistic, ROC curves demonstrated virtually identical performance of the MTOS and Ontario-based TRISS models. The poor performance of the Revised Trauma Score and the observation that its use led to the exclusion of 40% of cases with a higher mortality raises concerns regarding its use in the TRISS model.

Adult↗
PubMed1996

A reader's guide to the evaluation of screening studies.

In this article we will review how a reader should evaluate a screening study. A clinical problem involving screening mammography is presented. We then outline criteria to determine whether screening is appropriate for a given condition. A search for relevant articles is described followed by an outline of the steps used to appraise a screening study critically. An applicable study is examined in detail for such things as the quality of randomisation and outcomes measured. The results of this study are then applied to a patient considered for screening.

Breast Neoplasms↗
PubMed1995

Association of drug therapy with survival in cardiac arrest: limited role of advanced cardiac life support drugs.

OBJECTIVE: To generate hypotheses regarding the association of standard Advanced Cardiac Life Support (ACLS) drugs with human cardiac arrest survival. METHODS: This observational cohort study was conducted over a two-year period in the wards, intensive care units, and EDs of two tertiary care hospitals. Included werc adult patients who suffered cardiac arrest either inside or outside the hospital and who required epinephrine according to standard ACLS guidelines. Six standard ACLS drugs (given while CPR was in progress) were assessed for association with survival from resuscitation to one hour and to hospital discharge by univariate and multivariate logistic regression analyses. RESULTS: In the 529 patients studied, initial cardiac rhythm had no impact on the association between drug administration and survival. The time of drug administration (quartile of ACLS period) was associated with resuscitation for atropine (p < 0.05) and lidocaine (p < 0.01). The odds ratios (95% CIs) for successful resuscitation, after multivariate adjustment for potential confounders, were: a respiratory initiating cause, 3.7 (2.1 -6.4); each 5-minute increase in CPR-ACLS interval, 0.5 (0.4-0.7); each 5-minute duration of ACLS. 0.9 (()1.8- 1.0; atropine, 1.2 (1.0-1.3); bretylium. (0.4 (0.1-1.1); calcium 0.8 (0.2-2.4); lidocaine, 0.9 (0.7-1.1); procainamide. 21.0 (5.2-84.0) d sodium bicarbonate 1.2 (1.0-1.6). All other potential confounding variables entered into the model were not significantly associated with resuscitation. CONCLUSION: Initiating cause of arrest, time to ACLS, and duration of ACLS were important correlates of survival. Other than procainaimide, standard ACLS drugs had relatively little association with survival, but timing of administration may be an important factor. Further research using definitive large randomized controlled trials is warranted to assess the role of drug therapy in improving cardiac arrest survival.

Adult↗
PubMed1994

Decrease in left ventricular contractility after tumor necrosis factor-alpha infusion in dogs.

Whether systolic contractility or diastolic compliance changes soon after tumor necrosis factor-alpha (TNF-alpha) exposure is not known. Accordingly, we measured hemodynamics, left ventricular contractility using the slope of the end-systolic pressure-volume relationship, and diastolic pressure-volume relationships in six control dogs and in six dogs receiving 60 micrograms.kg-1.h-1 i.v. of TNF-alpha. Mean aortic pressure decreased by 22% 1 h after TNF-alpha infusion and remained decreased (P < 0.05). Cardiac output increased by 19% 1 h after TNF-alpha infusion and remained significantly greater than control values (P < 0.05). Left ventricular contractility decreased by 23% (P < 0.05) 1 h after TNF-alpha infusion and decreased by 52% (P < 0.01) 5 h after TNF-alpha infusion. The diastolic pressure-volume relationship did not change in the TNF-alpha group or the control group. Ejection fraction did not change after TNF-alpha infusion despite the decrease in contractility because afterload decreased. We conclude that TNF-alpha is important in causing the hypotensive, hyperdynamic circulation of sepsis. The new finding that left ventricular contractility is decreased shortly after TNF-alpha infusion suggests that TNF-alpha, or another mediator released very soon after TNF-alpha, is an important myocardial depressant factor.

Animals↗
PubMed1993

A simple multiple system organ failure scoring system predicts mortality of patients who have sepsis syndrome.

A simple multiple system organ failure (MSOF) score may predict mortality of patients who have sepsis syndrome. Using an MSOF scoring system, we prospectively determined the presence or absence of respiratory, cardiovascular, renal, hepatic, gastrointestinal, hematologic, and neurologic organ failure on day 1 of sepsis syndrome in 154 consecutive patients who had sepsis syndrome in the ICU of a tertiary care, teaching hospital. We used 30-day hospital mortality as the primary outcome variable. Overall 30-day mortality was 34 percent. There was a strong linear association between number of organ system failures and 30-day mortality (p < 0.0001). Mortality was 20 percent in patients who had less than 3 organ system failures (n = 111) and 70 percent in patients who had 3 or more organ system failures (n = 43). Survival was assessed using the Cox proportional hazards model and was found to be significantly different (p < 0.01) between the two groups defined by the aforementioned dichotomy after adjustment for age and sex using time to death as the primary outcome. The increase in relative risk of death associated with 3 or more organ system failures was 2.77 (95 percent confidence interval, 2.74 to 2.83). Using logistic regression, the adjusted odds ratios (OR) for covariates most predictive of mortality were hematologic (OR = 6.2), neurologic (OR = 4.4), hepatic (OR = 3.4), cardiovascular (OR = 2.6), and age (1.05 per year). The logistic model using the seven organ system failures and age as covariates accurately predicted outcome 75 percent of the time with a sensitivity of 51 percent and specificity of 87 percent. In conclusion, a simple scoring system tabulating the number of organ system failures present on day 1 of sepsis syndrome predicts the mortality of patients who have sepsis syndrome with reasonable accuracy.

Adult↗
PubMed1992

High-dose epinephrine in adult cardiac arrest.

BACKGROUND: Recent studies suggest that doses of epinephrine of 0.1 mg per kilogram of body weight or higher may improve myocardial and cerebral blood flow as well as survival in cardiac arrest. Such studies have called into question the traditional dose of epinephrine (0.007 to 0.014 mg per kilogram) recommended for advanced cardiac life support. METHODS: We randomly assigned 650 patients who had had cardiac arrest either in or outside the hospital to receive up to five doses of high-dose (7 mg) or standard-dose (1 mg) epinephrine at five-minute intervals according to standard protocols for advanced cardiac life support. Patients who collapsed outside the hospital received no advanced-life-support measures other than defibrillation before reaching the hospital. RESULTS: There was no significant difference between the high-dose group (n = 317) and the standard-dose group (n = 333) in the proportions of patients who survived for one hour (18 percent vs. 23 percent, respectively) or who survived until hospital discharge (3 percent vs. 5 percent). Among the survivors, there was no significant difference in the proportions who remained in the best category of cerebral performance (90 percent vs. 94 percent) and no significant difference in the median Mini-Mental State score (36 vs. 37). The exploration of clinically important subgroups, including those with out-of-hospital arrest (n = 335) and those with in-hospital arrest (n = 315), failed to identify any patients who appeared to benefit from high-dose epinephrine and suggested that some patients may have worse outcomes after high-dose epinephrine. CONCLUSION: High-dose epinephrine was not found to improve survival or neurologic outcomes in adult victims of cardiac arrest.

Adult↗
PubMedDate not supplied

Need for sedation in a patient undergoing active compression--decompression cardiopulmonary resuscitation.

The authors report the case of a 57-year-old man with a history of ischemic heart disease who presented to the emergency department with an acute myocardial infarction and hypotension. Despite aggressive pharmacotherapy, the patient's heart rate decreased, and he developed pulseless electrical activity within 15 minutes of his arrival. Cardiopulmonary resuscitation (CPR) was begun with an active compression-decompression (ACD) device, and the patient became agitated, making purposeful movements. When ACD-CPR was discontinued for a rhythm check, the patient had no pulse and became motionless. Agitation and purposeful movements occurred on two subsequent occasions with the initiation of ACD-CPR. The patient required physical restraints, sedation, and paralysis for personnel to perform endotracheal intubation and facilitate treatment. The implications of this case are discussed.

Angina Pectoris↗