Gregory L. Bryson

Does acute normovolemic hemodilution reduce perioperative allogeneic transfusion? A meta-analysis

UNLABELLED The objective of this study was to systematically review the literature and to statistically summarize the evidence evaluating acute normovolemic hemodilution (ANH). Prospective, randomized, controlled trials of ANH that reported either the proportion of patients exposed to allogeneic blood or the units of allogeneic blood transfused were included. All types and languages of publication were eligible. Of 1573 identified publications, 24 trials (containing a total of 1218 patients) were included in the meta-analysis. When all trials were pooled, ANH reduced the likelihood of exposure to allogeneic blood (odds ratio [OR] 0.31, 95% confidence interval [CI] 0.15, 0.62) and the total units of allogeneic blood transfused (weighted mean difference [WMD] -2.22 U, 95% CI -3.57, -0.86). However, there was marked heterogeneity of the results. In trials using a protocol to guide perioperative transfusion, ANH failed to reduce either the likelihood of transfusion (OR 0.64, 95% CI 0.31, 1.31) or the units administered (WMD -0.25 U, 95% CI -0.60, 0.10). Adverse events were incompletely reported. It is possible that biased experimental design is, in part, responsible for the reported efficacy of this technique. IMPLICATIONS after a systematic literature review, 24 randomized trials examining the role of acute normovolemic hemodilution were identified, pooled, and summarized using statistical techniques. Many studies reported an impressive reduction in blood transfused. Closer examination suggests that these reductions in blood exposure may be due to flawed study design.

Evidence-based clinical update : General anesthesia and the risk of delirium and postoperative cognitive dysfunction

PurposeThe purpose of this structured, evidence-based, clinical update was to identify the best evidence comparing general and regional anesthesia and their influence on delirium or cognitive dysfunction (POCD) in the postoperative period.SourceIn June 2005 a structured search of MEDLINE from 1966 to present using OVID software was undertaken. Medical subject headings and textwords describing both delirium and POCD were employed. OVID’s Therapy (sensitivity) algorithm was used to maximize the detection of randomized trials. The bibliographies of eligible publications were hand-searched to identify trials not identified in the electronic search. Publications enrolling children were excluded. Levels of evidence and grades of recommendations were scored using Centre for Evidence Based Medicine criteria.Principal findingsA total of 18 unique randomized controlled trials were identified: two evaluating delirium; ten evaluating POCD; and six evaluating both. Outcomes for delirium were abstracted from eight trials that enrolled 765 patients (387 regional anesthesia; 378 general anesthesia). Outcomes for POCD were identified from 16 trials that enrolled 2,708 patients (1,313 regional anesthesia; 1,395 general anesthesia). Both delirium (11-43%) and POCD (15-25%) were relatively common in trials actively seeking these outcomes. Consistent Level 2b evidence suggests no significant increase in delirium in patients receiving general anesthesia compared with those receiving regional anesthesia. Similarly, consistent Level 1 evidence indicates that exposure to general anesthesia is not significantly associated with POCD.ConclusionAvailable randomized controlled trials suggest that there is no significant difference in the incidence of delirium or POCD when general anesthesia and regional anesthesia are compared.RésuméObjectifIdentifier, par une mise à jour clinique structurée et fondée sur des données probantes, la meilleure preuve en comparant l’anesthésie générale et régionale et leur influence sur le délire ou le dysfonctionnement cognitif postopératoires (DCPO).SourceEn juin 2005, une recherche structurée a été entreprise dans MEDLINE, de 1966 à nos jours, en utilisant le logiciel OVID. Les vedettes-matières et les textes décrivant le délire et le DCPO ont été utilisés. Un algorithme thérapeutique (sensibilité) tiré de OVID a servi à optimaliser la détection d’études randomisées. Les bibliographies des études admissibles ont été fouillées manuellement pour découvrir les études non repérées dans la recherche électronique. Les recherches portant sur des enfants ont été exclues. Les niveaux d’évidence et les degrés de recommandations ont été évalués selon les critères du Centre for Evidence Based Medicine.Constatations principalesNous avons trouvé 18 études randomisées et contrôlées originales : deux évaluaient le délire, dix le DCPO et six évaluaient les deux. Les données sur le délire ont été extraites de huit études regroupant 765 patients (387 pour l’anesthésie régionale et 378 pour l’anesthésie générale). Les données sur le DCPO ont été tirées de 16 études sur 2 708 patients (1 313 pour l’anesthésie régionale et 1 395 pour l’anesthésie générale). Le délire (11 - 43 %) et le DCPO (15 - 25 %) étaient relativement fréquents dans les études qui recherchaient activement ces résultats. l’évidence d’un niveau 2b persistant montre qu’il n’y a pas d’augmentation significative du délire chez les patients sous anesthésie générale comparée à l’anesthésie régionale. De même, l’évidence d’un niveau 1 persistant indique que l’exposition à l’anesthésie générale n’est pas significativement associée au DCPO.ConclusionLes études randomisées et contrôlées accessibles montrent que l’incidence de délire ou de DCPO n’est pas significativement différente avec l’anesthésie générale ou régionale.

Patient selection in ambulatory anesthesia — An evidence-based review: part II

PurposeTo identify and characterize the evidence supporting decisions made in the care of patients with selected medical conditions undergoing ambulatory anesthesia and surgery. Conditions highlighted in this review include: the elderly heart transplantation, hyper-reactive airway disease, coronary artery disease, and obstructive sleep apnea.SourceA structured search of MEDLINE ( 1966–2003) was performed using keywords for ambulatory surgery and patient condition. Selected articles were assigned a level of evidence using Centre for Evidence Based Medicine (CEBM) criteria. Recommendations were also graded using CEBM criteria.Principal findingsThe elderly may safely undergo ambulatory surgery but are at increased risk for hemodynamic variation in the operating room. The heart transplant recipient is at increased risk of coronary artery disease and renal insufficiency and should undergo careful preoperative evaluation. The patient with reactive airway disease is at increased risk of minor respiratory complications and should be encouraged to quit smoking. The patient with coronary artery disease and recent myocardial infarction may undergo ambulatory surgery without stress testing if functional capacity is adequate. The patient with obstructive sleep apnea is at increased risk of difficult tracheal intubation but the likelihood of airway obstruction and apnea following ambulatory surgery is unknown.ConclusionAmbulatory anesthesia is infrequently associated with adverse outcomes, however, knowledge regarding specific patient conditions is of generally low quality. Few prospective trials are available to guide management decisions.RésuméObjectifIdentifier et caractériser la preuve à l’appui des décisions prises sur les soins à donner aux patients qui présentent des pathologies médicales ciblées et qui subissent une anesthésie en chirurgie ambulatoire. Les situations sélectionnées dans cette revue comprennent : la vieillesse, la transplantation cardiaque, l’affection respiratoire hyper-réactionnelle, la coronaropathie et l’apnée obstructive du sommeil.SourceUne recherche structurée dans MEDLINE (1966–2003) a été réalisée selon les mots dés pour la chirurgie ambulatoire et l’état du patient. Les articles choisis ont été cotés selon le niveau de preuve des critères du Centre for Evidence Based Medicine (CEBM). Les recommandations ont aussi été graduées selon les critères du CEBM.Constatations principalesLes personnes âgées peuvent subir une opération ambulatoire en toute sécurité, mais sont plus à risque de variation hémodynamique en salle d’opération. Les greffés cardiaques sont plus à risque de coronaropathie et d’insuffisance rénale et doivent avoir une évaluation préopératoire minutieuse. Les cas d’affection respiratoire réactionnelle sont plus à risque de complications respiratoires mineures et doivent être encouragés à cesser de fumer. Le patient atteint de coronaropathie, victime récente d’infarctus myocardique, peut être vu en chirurgie ambulatoire sans épreuve d’effort si la capacité fonctionnelle est adéquate. En cas d’apnée obstructive du sommeil, il y a plus de risque de difficulté d’intubation trachéale, mais la possibilité d’obstruction des voies aériennes et d’apnée à la suite d’une opération ambulatoire n’est pas connue.ConclusionLanesthésie ambulatoire n’est pas souvent associée à des complications, même si la connaissance de pathologies spécifiques est peu développée en général. Il existe peu d’études prospectives permettant de guider les décisions thérapeutiques.

The effect of perioperative aspirin therapy in peripheral vascular surgery : A decision analysis

Patients who undergo infrainguinal revascularization surgery are at increased risk for perioperative thrombotic complications. Aspirin decreases thrombotic events in the nonoperative setting; however, aspirin is often discontinued to avoid perioperative hemorrhagic complications. We used a decision analysis to determine whether aspirin should be discontinued before infrainguinal revascularization surgery. Two strategies were compared: aspirin cessation 2 wk before surgery and aspirin continuation throughout the perioperative period. Clinical events examined included myocardial infarction, thrombotic cerebrovascular accident, hemorrhagic cerebrovascular accident, gastrointestinal hemorrhage, and incisional hemorrhagic complications. Event rates and effect of aspirin were obtained by using MEDLINE. The outcomes were perioperative mortality, life expectancy, and quality-adjusted life expectancy. According to the model, continued aspirin use decreased perioperative mortality rates from 2.78% to 2.05%. Continued aspirin use increased life expectancy from 14.83 to 14.89 yr and increased quality-adjusted life expectancy from 14.72 to 14.79 yr. Aspirin increased the number of hemorrhagic complications by 2.46%, primarily because of an increased incidence of non-life-threatening complications.

The Value of Routine Preoperative Electrocardiography in Predicting Myocardial Infarction After Noncardiac Surgery

Objective:The added value of a preoperative electrocardiogram (ECG) in the prediction of postoperative myocardial infarction (POMI) and death was compared with clinical risk factors identified from the patients history. Summary of Background Data:An ECG is frequently performed before surgery to screen for asymptomatic coronary artery disease. However, the value of ECG abnormalities to predict POMI has been questioned. Methods:The study included 2967 noncardiac surgery patients >50 years of age from 2 university hospitals, who were expected to stay in the hospital for >24 hours. All data were obtained from electronic record-keeping systems. Patient history and ECG abnormalities were considered as potential predictors. Multivariate logistic regression analysis was used to obtain the independent predictors of POMI and all-cause in-hospital mortality. The area under the receiver operating characteristic curve (ROC area) was estimated to evaluate the ability of different models to discriminate between patients with and without the outcome. Results:A preoperative ECG was available in 2422 patients (80%) and 1087 (45%) of the ECGs showed at least one abnormality. The ROC area of the model that included the independent predictors of POMI obtained from patient history, ie, ischemic heart disease and high-risk surgery, was 0.80. ECG abnormalities that were associated with POMI were a right and a left bundle branch block. After adding these abnormalities in the regression model, the ROC area remained 0.80. Similar results were found for all-cause mortality. Conclusions:Bundle branch blocks identified on the preoperative ECG were related to POMI and death but did not improve prediction beyond risk factors identified on patient history.

Anesthesiologists’ and surgeons’ perceptions about routine pre-operative testing in low-risk patients: application of the Theoretical Domains Framework (TDF) to identify factors that influence physicians’ decisions to order pre-operative tests

BackgroundRoutine pre-operative tests for anesthesia management are often ordered by both anesthesiologists and surgeons for healthy patients undergoing low-risk surgery. The Theoretical Domains Framework (TDF) was developed to investigate determinants of behaviour and identify potential behaviour change interventions. In this study, the TDF is used to explore anaesthesiologists’ and surgeons’ perceptions of ordering routine tests for healthy patients undergoing low-risk surgery.MethodsSixteen clinicians (eleven anesthesiologists and five surgeons) throughout Ontario were recruited. An interview guide based on the TDF was developed to identify beliefs about pre-operative testing practices. Content analysis of physicians’ statements into the relevant theoretical domains was performed. Specific beliefs were identified by grouping similar utterances of the interview participants. Relevant domains were identified by noting the frequencies of the beliefs reported, presence of conflicting beliefs, and perceived influence on the performance of the behaviour under investigation.ResultsSeven of the twelve domains were identified as likely relevant to changing clinicians’ behaviour about pre-operative test ordering for anesthesia management. Key beliefs were identified within these domains including: conflicting comments about who was responsible for the test-ordering (Social/professional role and identity); inability to cancel tests ordered by fellow physicians (Beliefs about capabilities and social influences); and the problem with tests being completed before the anesthesiologists see the patient (Beliefs about capabilities and Environmental context and resources). Often, tests were ordered by an anesthesiologist based on who may be the attending anesthesiologist on the day of surgery while surgeons ordered tests they thought anesthesiologists may need (Social influences). There were also conflicting comments about the potential consequences associated with reducing testing, from negative (delay or cancel patients’ surgeries), to indifference (little or no change in patient outcomes), to positive (save money, avoid unnecessary investigations) (Beliefs about consequences). Further, while most agreed that they are motivated to reduce ordering unnecessary tests (Motivation and goals), there was still a report of a gap between their motivation and practice (Behavioural regulation).ConclusionWe identified key factors that anesthesiologists and surgeons believe influence whether they order pre-operative tests routinely for anesthesia management for a healthy adults undergoing low-risk surgery. These beliefs identify potential individual, team, and organisation targets for behaviour change interventions to reduce unnecessary routine test ordering.

Preoperative testing is inconsistent with published guidelines and rarely changes management

PurposeThe Canadian Anesthesiologists’ Society (CAS), the Ontario Preoperative Task Force (OPTF) and The Ottawa Hospital (TOH) have published guidelines detailing the indications for preoperative testing. The purpose of this study was to: (a) document compliance of testing practice at TOH-Civic Campus with published guidelines; and (b) determine the impact of preoperative testing on clinical management.MethodsFollowing Research Ethics approval all patients undergoing elective surgery at TOH-Civic Campus in the first three months of 2004 were identified. One hundred charts from each month were randomly selected and analyzed retrospectively by a single reviewer. The ordering and results of four preoperative tests were characterized. The indication for preoperative testing was identified from preoperative notes and the source of non-compliant orders was identified. Compliance with the CAS, OPTF, and TOH guidelines was documented. Abnormal test results were analyzed for evidence of a subsequent change in clinical management.ResultsThe charts of 294 of the 2,116 patients who underwent elective surgery at TOH-Civic Campus in the first three months of 2004 were reviewed. A total of 534 tests were ordered on 198 patients (67%). Non-compliance rates varied significantly (5-98%) depending on test and guideline analyzed. Results of 329 tests (61.6%) were normal. Management was changed by 14 of 534 tests ordered (2.6%). Surgery proceeded as scheduled in all cases.ConclusionThe majority of elective surgical patients undergo preoperative testing. Non-compliance with guidelines ranged from 5 to 98%. The results of most tests were normal and influenced management in only 2.6% of cases.RésuméObjectifLa Société canadienne des anesthésiologistes (SCA) ľOntario Preoperative Task Force (OPTF) et The Ottawa Hospital (TOH) ont publié des directives détaillées sur les indications de tests préopératoires. Le but de notre étude était de: (a) documenter la conformité de la pratique des tests au TOH-Civic Campus avec les directives publiées et (b) déterminer ľimpact des tests préopératoires sur la conduite clinique.MéthodeAvec ľaccord du Comité ďéthique de la recherche, nous avons repéré les dossiers de tous les patients opérés en chirurgie réglée au TOH-Civic Campus, au cours des trois premiers mois de 2004. Cent dossiers par mois ont été choisis au hasard et analysés rétrospectivement par un seul examinateur. Quatre tests préopératoires ont été caractérisés quant à leurs prescriptions et résultats. Ľindication de tests préopératoires a été trouvée dans les notes préopératoires et la source de prescriptions non conformes a été identifiée. La conformité avec les directives de la SCA, de ľOPTF et du TOH a été étudiée. Les résultats anormaux des tests ont été analysés pour savoir s’ils modifiaient la conduite clinique ultérieure.RésultatsLes dossiers de 294 des 2 116 patients opérés en chirurgie réglée au TOH-Civic Campus au cours des trois premiers mois de 2004 ont été revus. Il y a eu 534 tests demandés pour 198 (67 %) patients. Les taux de non-conformitéé variaient de façon significative (5–98 %) selon les tests et les directives analysées. Les résultats de 329 tests (61,6 %) étaient normaux. Le traitement a été changé par 14 des 534 tests. La chirurgie n’a été modifiée dans aucun cas.ConclusionLa majorité des patients de chirurgie réglée subissent des tests préopératoires. La non-conformité aux directives allait de 5 à 98 %. Les résultats de la plupart des tests étaient normaux et n’ont influencé le traitement que dans 2,6 % des cas.Objectif La Societe canadienne des anesthesiologistes (SCA) ľOntario Preoperative Task Force (OPTF) et The Ottawa Hospital (TOH) ont publie des directives detaillees sur les indications de tests preoperatoires. Le but de notre etude etait de: (a) documenter la conformite de la pratique des tests au TOH-Civic Campus avec les directives publiees et (b) determiner ľimpact des tests preoperatoires sur la conduite clinique.

Canadian Cardiovascular Society Guidelines on Perioperative Cardiac Risk Assessment and Management for Patients Who Undergo Noncardiac Surgery

The Canadian Cardiovascular Society Guidelines Committee and key Canadian opinion leaders believed there was a need for up to date guidelines that used the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system of evidence assessment for patients who undergo noncardiac surgery. Strong recommendations included: 1) measuring brain natriuretic peptide (BNP) or N-terminal fragment of proBNP (NT-proBNP) before surgery to enhance perioperative cardiac risk estimation in patients who are 65 years of age or older, are 45-64 years of age with significant cardiovascular disease, or have a Revised Cardiac Risk Index score ≥ 1; 2) against performing preoperative resting echocardiography, coronary computed tomography angiography, exercise or cardiopulmonary exercise testing, or pharmacological stress echocardiography or radionuclide imaging to enhance perioperative cardiac risk estimation; 3) against the initiation or continuation of acetylsalicylic acid for the prevention of perioperative cardiac events, except in patients with a recent coronary artery stent or who will undergo carotid endarterectomy; 4) against α2 agonist or β-blocker initiation within 24 hours before surgery; 5) withholding angiotensin-converting enzyme inhibitor and angiotensin II receptor blocker starting 24 hours before surgery; 6) facilitating smoking cessation before surgery; 7) measuring daily troponin for 48 to 72 hours after surgery in patients with an elevated NT-proBNP/BNP measurement before surgery or if there is no NT-proBNP/BNP measurement before surgery, in those who have a Revised Cardiac Risk Index score ≥1, age 45-64 years with significant cardiovascular disease, or age 65 years or older; and 8) initiating of long-term acetylsalicylic acid and statin therapy in patients who suffer myocardial injury/infarction after surgery.

Effect of β-blocker Prescription on the Incidence of Postoperative Myocardial Infarction after Hip and Knee Arthroplasty

Background:American College of Cardiology/American Heart Association guidelines recommend &bgr;-blockade for selected low- and intermediate-risk noncardiac surgery patients. The authors evaluated the effect of perioperative &bgr;-blockade on postoperative myocardial infarction (POMI) in low-risk patients undergoing intermediate-risk surgery. Methods:Patients who underwent elective hip or knee arthroplasty between January 1, 2002 and June 30, 2006 were identified. POMI was defined as a Troponin T value of more than 0.1 ng · ml−1. Patients were divided into three groups: those prescribed a &bgr;-blocker on the day of surgery and throughout their hospital stay (or 7 days, whichever came first), those prescribed a &bgr;-blocker on the day of surgery but discontinued during the first 7 days, and those not prescribed a &bgr;-blocker on the day of surgery. Propensity analysis and logistic regression were used to determine the independent association of &bgr;-blocker exposure on POMI. Results:Of the 5,158 arthroplasty patients, 992 (18%) were treated with &bgr;-blockers on the day of surgery. This &bgr;-blocker was discontinued in 252 patients (25%). POMI occurred in 77 patients (1.5%). Discontinuation of &bgr;-blocker prescription was significantly associated with POMI (odds ratio 2.0; 95% CI 1.1–3.9) and death (odds ratio 2.0; 95% CI 1.0–3.9). Conclusion:After adjustment for confounders, discontinuation of &bgr;-blocker prescription during the first week after surgery was significantly associated with POMI and death. These findings confirm the American College of Cardiology/American Heart Association Guidelines on Perioperative Cardiovascular Evaluation and Care for Noncardiac Surgery, which recommend not to withdraw &bgr;-blocker therapy.

Les tests préopératoires ne correspondent pas aux directives publiées et modifient rarement la ligne de conduite

PurposeThe Canadian Anesthesiologists’ Society (CAS), the Ontario Preoperative Task Force (OPTF) and The Ottawa Hospital (TOH) have published guidelines detailing the indications for preoperative testing. The purpose of this study was to: (a) document compliance of testing practice at TOH-Civic Campus with published guidelines; and (b) determine the impact of preoperative testing on clinical management.MethodsFollowing Research Ethics approval all patients undergoing elective surgery at TOH-Civic Campus in the first three months of 2004 were identified. One hundred charts from each month were randomly selected and analyzed retrospectively by a single reviewer. The ordering and results of four preoperative tests were characterized. The indication for preoperative testing was identified from preoperative notes and the source of non-compliant orders was identified. Compliance with the CAS, OPTF, and TOH guidelines was documented. Abnormal test results were analyzed for evidence of a subsequent change in clinical management.ResultsThe charts of 294 of the 2,116 patients who underwent elective surgery at TOH-Civic Campus in the first three months of 2004 were reviewed. A total of 534 tests were ordered on 198 patients (67%). Non-compliance rates varied significantly (5-98%) depending on test and guideline analyzed. Results of 329 tests (61.6%) were normal. Management was changed by 14 of 534 tests ordered (2.6%). Surgery proceeded as scheduled in all cases.ConclusionThe majority of elective surgical patients undergo preoperative testing. Non-compliance with guidelines ranged from 5 to 98%. The results of most tests were normal and influenced management in only 2.6% of cases.RésuméObjectifLa Société canadienne des anesthésiologistes (SCA) ľOntario Preoperative Task Force (OPTF) et The Ottawa Hospital (TOH) ont publié des directives détaillées sur les indications de tests préopératoires. Le but de notre étude était de: (a) documenter la conformité de la pratique des tests au TOH-Civic Campus avec les directives publiées et (b) déterminer ľimpact des tests préopératoires sur la conduite clinique.MéthodeAvec ľaccord du Comité ďéthique de la recherche, nous avons repéré les dossiers de tous les patients opérés en chirurgie réglée au TOH-Civic Campus, au cours des trois premiers mois de 2004. Cent dossiers par mois ont été choisis au hasard et analysés rétrospectivement par un seul examinateur. Quatre tests préopératoires ont été caractérisés quant à leurs prescriptions et résultats. Ľindication de tests préopératoires a été trouvée dans les notes préopératoires et la source de prescriptions non conformes a été identifiée. La conformité avec les directives de la SCA, de ľOPTF et du TOH a été étudiée. Les résultats anormaux des tests ont été analysés pour savoir s’ils modifiaient la conduite clinique ultérieure.RésultatsLes dossiers de 294 des 2 116 patients opérés en chirurgie réglée au TOH-Civic Campus au cours des trois premiers mois de 2004 ont été revus. Il y a eu 534 tests demandés pour 198 (67 %) patients. Les taux de non-conformitéé variaient de façon significative (5–98 %) selon les tests et les directives analysées. Les résultats de 329 tests (61,6 %) étaient normaux. Le traitement a été changé par 14 des 534 tests. La chirurgie n’a été modifiée dans aucun cas.ConclusionLa majorité des patients de chirurgie réglée subissent des tests préopératoires. La non-conformité aux directives allait de 5 à 98 %. Les résultats de la plupart des tests étaient normaux et n’ont influencé le traitement que dans 2,6 % des cas.Objectif La Societe canadienne des anesthesiologistes (SCA) ľOntario Preoperative Task Force (OPTF) et The Ottawa Hospital (TOH) ont publie des directives detaillees sur les indications de tests preoperatoires. Le but de notre etude etait de: (a) documenter la conformite de la pratique des tests au TOH-Civic Campus avec les directives publiees et (b) determiner ľimpact des tests preoperatoires sur la conduite clinique.