[Erythrocyte transfusions: an evidence-based approach]. / La transfusion érythrocytaire : une approche basée sur les données probantes.

Few randomized controlled studies, the only trial design where causality can be established between an intervention and the benefits or harms thereof, have been published on the benefits and risks of a restrictive vs a liberal transfusion strategy. We review the 19 controlled studies on erythrocyte transfusion thresholds published since the eighties. These studies suggest that, overall, morbidity (including cardiac morbidity) and mortality, along with hemodynamic, respiratory and oxygen transport variables, are similar when a restrictive transfusion strategy (transfusion threshold between 7 and 8 g/dL) or a liberal strategy (transfusion threshold of 10 g/dL) are used. In fact, a restrictive strategy can even be associated with a number of benefits. The relevance of a higher transfusion threshold in view of avoiding morbidity in patients presenting a cardiovascular risk is unlikely, at least uncertain. Finally, anaemia has little or no impact on functional recovery and on quality of life, whether in the immediate or late postoperative period. It is clear that a restrictive strategy is associated with a reduced exposure to red cell transfusions, allowing a reduction in transfusion-related adverse events. Thus, all red cell transfusions must be tailored to the patient's needs, at the time the need prevails. In conclusion, most recommendations on transfusion practice are limited by the lack of evidence-based data and reveal our ignorance on the topic. High quality clinical trials in different patient populations must become available in order to determine optimal transfusion practices. Since then, a restrictive strategy aiming for a moderately anaemic threshold (7-8 g/dL) is appropriate under most circumstances.

Cardiac surgery with cardiopulmonary bypass: does aprotinin affect outcome?

BACKGROUND: Aprotinin, a non-specific serine protease inhibitor, has been used for two decades to reduce perioperative blood loss and the risk for allogeneic transfusion in cardiac surgery. This study evaluated the effects of aprotinin on outcome (mortality, cardiac events, renal failure, and cerebrovascular events) in such patients undergoing cardiac surgery with cardiopulmonary bypass. METHODS: Data were obtained in patients who received a strict blood conservation protocol: no antifibrinolytic therapy when at low risk (n = 854) and aprotinin (n = 1210) when at high risk for blood transfusion. Relative risk of different pre- and intra-operative variables was calculated for the different outcome variables. Backward stepwise logistic regression analysis was used to identify the independent risk factors associated with the different outcome variables. Statistical significance was accepted at P < 0.01. RESULTS: Postoperative mortality and morbidity were higher in the aprotinin group but this was related to an increased incidence of perioperative risk factors. Mortality was similar to that predicted by the Euroscore. Complex surgery was the only independent variable associated with postoperative cardiac events. Preoperative heart failure, preoperative creatinine > 1.5 mg dl(-1), urgent, and redo surgery were the independent variables associated with postoperative haemodialysis. Age > 70 yr was identified as the only independent variable associated with neurologic dysfunction. CONCLUSIONS: In the present study, patients receiving aprotinin as part of a strict blood conservation strategy represent a population at high risk for postoperative complications. For the outcome variables studied, aprotinin administration was not identified as an independent risk factor.

The coagulopathy of massive transfusion.

Recently, the Groupe d'Intérêt en Hémostase Périopératoire reviewed the pathophysiology of coagulopathy in massively transfused, adult and previously haemostatically competent patients in both elective surgical and trauma settings. In this article, we focus on our main observations. First, in most cases, the onset and severity of coagulopathy associated with massive transfusion differs depending on whether haemorrhage occurs as a result of trauma or elective surgery. In trauma patients, tissue trauma is uncontrolled, the interval between haemorrhage and treatment can vary widely, hypovolemia, shock and hypothermia are frequent, and coagulopathy is often related to the development of disseminated intravascular coagulation. Monitoring of haemostasis occurs late, when coagulopathy is installed, and treatment can be very difficult. In elective surgery patients, the situation remains controlled and, in most cases, a decrease in fibrinogen concentration is observed initially while thrombocytopenia is a late occurrence. Monitoring of haemostasis is ongoing and treatment is usually much simpler. Second, blood products have changed over time and this has affected the management of the bleeding patient. Contrary to the recommendations of studies published at a time when whole blood was readily available, the first line of treatment (at least in elective surgery patients) ought to be with fresh-frozen plasma to correct decreased levels of coagulation factors. The role of recombinant activated factor VII to treat bleeding that cannot be controlled by conventional measures remains to be clarified. Coagulopathy associated with massive transfusion remains an important clinical problem. Treatment strategies must be adapted to the context and to the blood products available. Nevertheless, the level of evidence supporting specific treatment options is low and more studies are required to guide our management of massively transfused patients.

Patients' perceptions of cardiac anesthesia services: a pilot study.

PURPOSE: To develop an instrument to measure patients' perceptions of the services provided by anesthesiologists, an important indicator of quality for which little information is available. METHODS: The scale of patients' perceptions of cardiac anesthesia services (SOPPCAS) is composed of 17 Likert-type and sociodemographic questions. Data collection was conducted on T-1 (fourth postoperative day) and T-2 (15 days postoperatively). In addition, we employed the Marlow-Crowne scale and a short form of the Psychological Symptoms Index to verify the influence of social desirability and psychological distress respectively. Data analysis included a principal component analysis (PCA). RESULTS: One hundred seventy patients answered the questionnaires at T-1 and 133 patients at T-2. Cronbach alpha of the SOPPCAS was 0.58. PCA revealed four perioperative factors: patient/anesthesiologist interactions, preoccupations related to anesthesia, experience with anesthesia and pain management. Global mean satisfaction was 4.45 +/- 0.64 (maximum score 6.0). Main items related to satisfaction were: satisfaction with premedication, empathy from anesthesiologists, pain management. Main items related to dissatisfaction were: lack of information on blood transfusion and recall of endotracheal intubation. A score of 14/20 was obtained for social desirability. Social desirability did not influence the construct of the SOPPCAS. CONCLUSION: We developed, using rigorous methods, an instrument to measure patients' perceptions of the quality of cardiac anesthesia services. Global mean satisfaction with anesthesia services was moderately high contrary to previous studies where it was high. Finally, the SOPPCAS should allow anesthesiologists to improve the quality of the care they provide.

[Reproducibility and interchangeability of the Thromboelastograph, Sonoclot and Hemochron activated coagulation time in cardiac surgery]. / Reproductibilité et interchangeabilité du Thromboélastographe, Sonoclot et du temps de coagulation activé (Hémochron), en chirurgie cardiaque

PURPOSE: Despite their common use in cardiac surgery, few studies have evaluated the reproducibility of the Thromboelastograph (TEG), of the Sonoclot (SCT), and of the activated coagulation time with celite (ACT-C) or kaolin (ACT-K) measured with the Hemochron, in clinical conditions of on-site monitoring of hemostasis. This study determined the reproducibility of those measurements, and evaluated the ability of various devices to substitute for the ACT-C. METHODS: Blood samples collected from 20 volunteers and 21 patients undergoing myocardial revascularization were analyzed in the two channels of the TEG, in two SCT and four Hemochron analyzers. The overall of TEG and SCT coagulation profiles were analyzed by a computerized TEG and an experienced observer respectively. The variation rate (V%) was calculated for each variable. The ability of ACT-K and SCT to substitute for ACT-C under different clinical conditions was evaluated. RESULTS: ACT-C and ACT-K V% ranged between 5.6% and 10.8% and between 6.7% and 12.4% respectively. TEG and SCT V% ranged between 3.1% and 9.5% and between 5.8% and 33.6% respectively, according to different conditions and parameters. In volunteers and non-heparinized patients, the ACT-C and ACT-K were interchangeable. No other test can substitute for the ACT-C when patients are heparinized during cardiopulmonary bypass (CPB). CONCLUSIONS: In the clinical conditions of use, on-site hemostasis monitoring devices providing the most reproducible measurements are, in decreasing order, the TEG, the Hemochron and the SCT. In heparinized patients and during CPB, results from different tests are not interchangeable, stressing the importance of establishing appropriate instrument-specific values for monitoring anticoagulation during cardiac surgery.

Pharmacological strategies for blood conservation in cardiac surgery: erythropoietin and antifibrinolytics.

PURPOSE: We review the clinically important benefits of the two principal pharmacological strategies, erythropoietin (EPO) and antifibrinolytics (aprotinin and lysine analogues), to decrease transfusion of allogeneic blood products (ABP) during and after cardiac surgery. SOURCE: Articles were selected from an ongoing review of the literature, with special attention to meta-analyses dealing with EPO and/or antifibrinolytics and cardiac surgery. PRINCIPAL FINDINGS: The few studies available include a number of patients insufficient to allow definitive conclusions on the benefits of EPO in cardiac surgery. Further studies are required to determine the optimal dose of EPO and to compare its cost-effectiveness with other blood sparing strategies in this context. Both aprotinin and lysine analogues effectively decrease ABP transfusions and the incidence of re-thoracotomy. In addition, high-dose aprotinin reduces cerebrovascular morbidity and mortality after cardiopulmonary bypass. Several mechanisms have been put forward to explain these beneficial effects, some of which could well be common to all antifibrinolytics. The clinical benefits of aprotinin's unique anti-inflammatory effect are not entirely clear but the finding that it reduces the incidence of stroke and death is certainly a major argument in favor of its utilization. Yet, we have to ensure that aprotinin's benefits are not offset by side-effects such as allergy. CONCLUSIONS: We still need large scale studies to definitely confirm the benefits and exclude the deleterious effects of these drugs on outcomes other than ABP requirements. At present, aprotinin is the only agent that has been shown to reduce the risk of cerebrovascular accident and mortality after cardiac surgery in adults.

Patient satisfaction with anesthesia services.

PURPOSE: The evaluation of services by patients is an essential component of continuous quality improvement in anesthesiology. Little is known, however, about how to achieve this objective. Our goal was to conduct a systematic review of all available studies on patient satisfaction with anesthesia services, thereby ascertaining the present level of knowledge in this field and suggesting ways of improving current measurement methodologies. SOURCE: We reviewed relevant major data banks--Medline, Dissertation Abstract, Psyclit and Cochrane--between 1980 and 2000 and bibliographies from primary sources. We used the following keywords for our search: quality improvement, anesthesia, quality, patient perceptions, consumer satisfaction, continuous quality improvement, outcome measures. PRINCIPAL FINDINGS: The review yielded 14 pertinent studies. Studies were divided into two groups (A & B), according to the quality of the psychometric evaluation (tests performed to verify the reliability and validity of an instrument). While all studies reported high levels of patient satisfaction with anesthesia services, many used methods of questionable value. None of the 14 studies controlled for any confounding variables, such as social desirability. Four studies had seriously biased their data collection and the majority of the studies lacked rigour in the development of the instrument used to measure patient satisfaction. Only one study presented a definition of the concept measured, and none provided a conceptual model of patients' satisfaction with anesthesia services. CONCLUSION: The currently available studies of patient satisfaction are of questionable value. Only rigorous methods and reliable instruments will yield valid and clinically relevant findings of this important issue in anesthesiology.

Difficult separation from cardiopulmonary bypass and deltaPCO2.

PURPOSE: Veno-arterial and regional differences of the partial pressure in CO2 (deltaPCO2), may be used as index to evaluate the adequacy of the cardiac output to the oxygen consumption. To determine the incidence of elevated deltaPCO2 and its relationship with difficult separation from bypass (DSB) in patients undergoing cardiac surgery, we conducted a prospective observational cohort study. METHODS: Data were collected from 58 consecutive patients undergoing various cardiac operations requiring cardiopulmonary bypass (CPB). During the procedure, arterial and venous blood gases and lactate were sampled. Blood was drawn after induction of anesthesia, during bypass and at the closure of the chest wall. Difficult separation from bypass was defined as a systolic arterial pressure < 80 mmHg, and diastolic pulmonary artery pressure > 15 mmHg during progressive separation from CPB with inotropic or mechanical support of cardiac function, or hemodynamic instability resulting in reintroduction of extra-corporeal circulation or insertion of an intra-aortic balloon pump. RESULTS: In our study, 65% of the samples were associated with elevated deltaPCO2 (> 6 mmHg). Variables associated with difficult weaning were LVEF; duration of bypass and aortic cross-clamping, pre-bypass deltaPCO2 and in-bypass lactate values (P < 0.05). Multivariable analysis identified the pre-bypass deltaPCO2 and the duration of bypass as predictors of DSB. CONCLUSION: Elevated deltaPCO2 is frequently observed during cardiac surgery and values obtained before bypass were associated with DSB. The deltaPCO2 gradients could be used as marker of the adequacy of tissue perfusion during cardiac surgery.

Transfusions in patients undergoing cardiac surgery with autologous blood.

PURPOSE: Determinants of allogeneic blood use in cardiac surgery include preoperative factors such as female sex, age, body weight, hematocrit and red cell volume. We verified if these variables also predicted the need for allogeneic transfusions when autologous blood is predonated. METHODS: Demographic and intraoperative variables, hemoglobin concentrations and transfusion requirements in patients undergoing cardiopulmonary bypass with autologous blood predonation were reviewed. Multivariate logistic regression and RECPAM tree-growing analyses were applied to identify the preoperative predictors of allogeneic transfusion in these patients. RESULTS: Data from 230 patients included in our autologous blood program between 1995 and 1998 were analysed. Patients undergoing complex/reoperative surgical procedures and patients over age 64yr with a low red cell volume (<2070ml) undergoing simple procedures were more likely to require allogeneic red cells. Younger patients with a low red cell volume undergoing simple procedures carried an intermediate risk. Allogeneic transfusion was avoided in 95% of patients undergoing simple procedures when red cell volume > or = 2070ml. CONCLUSIONS: In our institution, complex/reoperative surgery, low red cell volume and increased age are the main factors associated with the need for allogeneic red cell transfusion despite autologous blood predonation. Knowledge of the factors that limit the effectiveness of predonation with respect to allogeneic blood exposure should help clinicians decide which cardiac surgical patients should be included in autologous blood programs.

Clinimetric scale to measure surgeons' satisfaction with anesthesia services.

PURPOSE: Continuous quality improvement is of increasing interest to anesthesiologists. Since surgeons are coworkers and important clients of anesthesiologists, the level of satisfaction of surgeons with anesthesia services should be explored to optimize quality. The purpose of this study was, first, to introduce the concept of surgeons as clients of anesthesiologists and second, to develop and test an instrument to measure surgeons' satisfaction, the Surgeon Satisfaction with Anesthesia Services (SSAS) scale. METHODS: A conceptual model of surgeon satisfaction with anesthesia services was created before the development of the SSAS scale. The scale, composed of socio-demographic, Likert-type and open-ended questions was sent to a sample of 250 surgeons selected randomly by the Collège des Médecins du Québec. Exploratory factorial analysis were performed on the results. RESULTS: A Cronbach's alpha of 0.84 was obtained for internal consistency. Exploratory factorial analysis yielded two subscale factors: a) clinical expertise and b) attitudes and behaviour Global mean of surgeons'satisfaction was moderately high (3.11/4.0). Satisfaction was not related to sociodemographic variables. Very high scores were obtained for items related to clinical expertise. Items related to attitudes and behaviour obtained lower scores. A significant difference was obtained between both factors (t = -5.732, P = 0.0001). CONCLUSION: The SSAS scale is a new instrument to evaluate surgeon satisfaction. Overall, surgeons seem satisfied with anesthesia services, but many areas of dissatisfaction persist. Further discussions with surgeons should be encouraged, in view of improving the perceptions of the quality of anesthesia services and interprofessional relationships.

Factors predictive of oxygen consumption during the immediate postoperative period in open heart surgery.

BACKGROUND: Postoperative oxygen consumption (VO2) is critical during the recovery period that follows open heart surgery and depends on patient characteristics and surgical factors. OBJECTIVE: To explore the surgical and patient-related factors that may influence VO2 during the early postoperative period. DESIGN: Prospective study. SETTING: Postoperative intensive care unit. PATIENTS: Study participants were 50 consecutive patients undergoing elective open heart surgery. There were 39 men and 11 women, with a mean age of 58+/-10 years. MEASUREMENTS AND MAIN RESULTS: VO2, oxygen extraction and arterial lactate were measured 1, 4, 12 and 24 h postoperatively. VO2 increased significantly during the first 12 h and stabilized thereafter. Oxygen extraction remained stable through the first 24 h. Covariance analysis on repeated measures showed that the extracorporeal circulatory period (P<0.01), age (P<0.01), body temperature (P<0.05) and use of noradrenalin (P<0.05) were predictive factors influencing postoperative VO2. Although arterial lactate increased significantly during the first 12 h period, no correlation with VO2 was found. However, covariance analysis showed that female sex, patient age (older than 65 years) and bypass period were positive correlating factors for the increase in arterial lactate. CONCLUSIONS: Patient VO2 need is decreased early after open heart surgery and returns to normal after 12 h. Surgical and patient-specific factors are responsible for these changes. Arterial lactate measurements were not found to be reliable indexes of VO2 need during this period.

Low-dose aprotinin is ineffective to treat excessive bleeding after cardiopulmonary bypass.

BACKGROUND: Uncontrolled clinical experience at our institution suggested that low-dose aprotinin could control excessive bleeding after cardiopulmonary bypass (CPB). A randomized clinical trial was conducted to determine the efficacy of low-dose aprotinin in the treatment of hemorrhage after cardiac surgery. METHODS: One hundred seventy-one patients undergoing cardiac surgery with CPB were included. Forty-four patients (26%) bled significantly in the intensive care unit (>100 mL/h) and received either aprotinin (200,000 KIU bolus + 100,000 KIU/h for 8 hours) or placebo in addition to our standard management of excessive bleeding. RESULTS: Median bleeding before study drug administration was not different between aprotinin (200 mL) and placebo (212.5 mL) groups. Bleeding decreased significantly with time and similarly in both groups. Ninety-five percent of patients required transfusions in both groups. Median blood products transfused were 13 and 8 units per patient in the aprotinin and placebo groups respectively (p = NS). CONCLUSIONS: Routine administration of low-dose aprotinin as part of the treatment protocol to control hemorrhage after CPB does not reduce bleeding or transfusion requirements and, therefore, cannot be recommended.