Editorial: The importance of cumulative meta-analyses and implications for B-type natriuretic peptide research in non-cardiac surgery

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Editorial: Prof Lundgren’s significant contribution to SAJAA and its future

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EDITORIAL: The need for uniformity in research definitions and the Standardized Endpoints for Perioperative Medicine (StEP) initiative

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Editorial: Recommendations and regulations to decrease bias, increase access to clinical data and improve the quality of evidence-based medicine for all

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Myocardial injury after non-cardiac surgery: a new clinical entity

Objectives: The objective was to determine the diagnostic criteria of a prognostically important troponin elevation following non-cardiac surgery. Background: A postoperative troponin leak following non-cardiac surgery is independently associated with 30- day mortality. Importantly, even what was previously considered to be an insignificant troponin leak has been independently associated with 30-day mortality in unselected surgical patients ≥ 45 years of age.1 Method: This study forms part of the prospective observational study known as the VISION (Vascular Events In Noncardiac Surgery Patients Cohort Evaluation) study.1 Diagnostic criteria were established for prognostically important myocardial injury following non-cardiac surgery from 15 000+ patients. A Cox regression analysis was undertaken to determine the independent predictors of 30-day mortality following non-cardiac surgery. The potential independent variables entered into the regression included preoperative variables, perioperative complications, and possible diagnostic criteria for myocardial injury after non-cardiac surgery. Results: Elevated troponin after non-cardiac surgery (without any evidence of a non-ischaemic cause like sepsis), independently predicted 30-day mortality. The presence of an ischaemic feature, as required for the Universal definition of myocardial infarction, did not change the diagnostic performance of the elevated troponin alone. Conclusion: Myocardial injury after non-cardiac surgery should be considered a new clinical entity. A troponin leak alone is considered to be prognostically important. The presence of ischaemic features should not be considered as a criterion for intervention in troponin-positive patients following non-cardiac surgery.Keywords: myocardial injury, non-cardiac surgery, new clinical entit

Taking an idea to a research protocol

We present a nine-step process to assist with developing an idea into a research protocol. This process ensures that evidence-based medicine practice is followed to prevent redundant research questions. The first step is to identify broad research ideas with a potentially “weak” evidence base, rather than starting with a specific research question. The second step is to identify the knowledge gap within the intended field of research by examining the background literature. Thirdly, the focus will be on the “foreground knowledge” needed to frame a potential research question. The fourth step uses this potential research question to conduct a comprehensive literature research, and aims to determine whether or not the question has been asked before. The fifth step entails writing a study one-page summary which provides a succinct summary of what is intended. The sixth step involves writing the protocol. The rigid process of protocol writing will ensure that a number of important practical study issues are dealt with timeously. The seventh step is to discuss the protocol with experts. Their input will make the protocol more robust. The eighth step necessitates making a “social contract” that requires public commitment to the project. The final step is to write a grant application for the study. This serves to allow the researcher to identify the funding priorities of potential grant-funding agencies, thereby allowing the researcher to frame his or her research in such a manner that the financial support necessary for the success of the project will hopefully be ensured.Keywords: research; anaesthesia; protoco

Validating the utilisation of venous bicarbonate as a predictor of acute kidney injury in crush syndrome from sjambok injuries

Background. Crush injury secondary to sjambok beatings is a well-described phenomenon in southern Africa. Owing to a number of factors, it can result in acute kidney injury (AKI). In 1992, Muckart et al. described a risk stratification system using venous bicarbonate (VB) that can be used in the management of these patients.Objective. To validate this score in the modern era of AKI risk stratification.Methods. A retrospective study was performed on a local trauma database from June 2010 to December 2012. All patients with crush injury from sjambok/blunt instrument beatings were included in the analysis. VB was compared with the Kidney Disease Improving Global Outcomes scoring system for AKI. Serum base excess (BE) and creatine kinase were also examined as biomarkers. The endpoints were the need for renal replacement therapy (RRT) and mortality.Results. Three hundred and ten patients were included. The overall mortality rate was 1.9%, 14.8% of patients had AKI, and 3.9% required RRT. Both VB and BE performed well in RRT prediction, with areas under the receiver operating characteristic curve of 0.847 (95% confidence interval (CI) 0.756 - 0.938; p<0.001) and 0.871 (95% CI 0.795 - 0.947; p<0.001), respectively. The sensitivity and specificity of BE were 83.3% and 80.2% at an optimal cut-point of –7.25 mmol/L, while those of VB were 83.3% and 79.5% at an optimal cut-point of 18.85 mmol/L. VB was significantly different across the AKI risk groups (p<0.001), in keeping with the original Muckart risk stratification system.Conclusion. The risk stratification score using VB is valid and should continue to be used as a tool in the management of patients with sjambok injuries. BE performs well in predicting the need for RRT, with a value of <–7.25 mmol/L indicating severe injury

The impact of acute preoperative beta-blockade on perioperative cardiac morbidity and all-cause mortality in hypertensive South African vascular surgery patients

Background. Acute β-blockade has been associated with poor perioperative outcomes in non-cardiac surgery patients, probably as a result of β-blocker-induced haemodynamic instability during the perioperative period, which has been shown to be more severe in hypertensive patients.Objective. To determine the impact of acute preoperative β-blockade on the incidence of perioperative cardiovascular morbidity and allcause mortality in hypertensive South African (SA) patients who underwent vascular surgery at a tertiary hospital.Methods. We conducted two separate case-control analyses to determine the impact of acute preoperative β-blockade on the incidence of major adverse cardiovascular events (MACEs, a composite outcome of a perioperative troponin-I leak or all-cause mortality) and perioperative troponin-I leak alone. Case and control groups were compared using χ2, Fisher’s exact, McNemar’s or Student’s t-tests, where applicable. Binary logistic regression was used to determine whether acute preoperative β-blocker use was an independent predictor of perioperative MACEs/troponin-I leak in hypertensive SA vascular surgery patients.Results. We found acute preoperative β-blockade to be an independent predictor of perioperative MACEs (odds ratio (OR) 3.496; 95% confidence interval (CI) 1.948 - 6.273; p<0.001) and troponin-I leak (OR 5.962; 95% CI 3.085 - 11.52; p<0.001) in hypertensive SA vascular surgery patients.Conclusions. Our findings suggest that acute preoperative β-blockade is associated with an increased risk of perioperative cardiac morbidity and all-cause mortality in hypertensive SA vascular surgery patients

Postoperative atrial fibrillation in patients on statins undergoing isolated cardiac valve surgery: a meta-analysis

Introduction: The efficacy of perioperative statin therapy in decreasing postoperative morbidity in patients undergoing valve replacements and repairs is unknown. The aim of our study was to determine whether or not the literature supports the hypothesis that statins decrease postoperative atrial fibrillation (AF), and hence improve short-term postoperative outcomes in patients undergoing isolated cardiac valve surgery.Method: We conducted a meta-analysis of studies on postoperative outcomes associated with statin therapy following isolated valve replacement or repair. The data was taken from published studies on valvular heart surgery patients. Participants were patients who underwent either isolated cardiac valve replacement or repair. Patients in the intervention group received statins prior to their surgery. Three databases were searched: Ovid Healthstar, 1966 to April 2012; Ovid Medline, 1946 to 31 May 2012; and Embase, 1974 to 30 May 2012. The meta-analysis was conducted using Review Manager® version 5.1.Results: Statins did not decrease the incidence of postoperative AF in patients undergoing isolated cardiac valve surgery [odds ratio (OR) 1.19, 95% confidence interval (CI): 0.80– 1.77)], although there was significant heterogeneity for the outcome of postoperative AF (I2 55%, 95% CI: 27–72). Statins were associated with a decrease in 30-day mortality (OR 0.43, 95% CI: 0.24–0.75).Conclusion: Although this meta-analysis suggests that chronic statin therapy did not prevent postoperative AF in unselected valvular heart surgical patients, the heterogeneity indicates that this outcome should be viewed with caution and further research is recommended.Keywords: atrial fibrillation, cardiac surgery, statin

Myocardial injury after non-cardiac surgery: Time to shed the ignorance

Perioperative cardiovascular complications are common and place a significant burden on public healthcare systems. A large proportion of such complications are due to a new clinical entity, i.e. myocardial injury after non-cardiac surgery (MINS). It is important to understand MINS, its prognosis and management in the perioperative period. A literature review of MINS was done. MINS is defined as an elevated postoperative cardiac troponin level that was considered as resulting from myocardial ischaemia without evidence of a non-ischaemic cause for the troponin elevation. The perioperative milieu (surgical stress response, sympathetic activation, hypercoagulability, hypotension, bleeding, anaemia and pain) contributes to the pathophysiology of a relative myocardial hypoperfusion and ischaemia, which differentiates MINS from myocardial infarction in non-surgical patients. Globally, >7% of adults ≥45 years of age suffer MINS, with South African (SA) studies confirming similar event rates. More than 80% of MINS patients are asymptomatic for myocardial ischaemia, and therefore would not fulfil the universal definition of myocardial infarction, despite having a similar prognosis to those with the latter condition. Accurate diagnosis of MINS therefore relies on routine daily postoperative cardiac troponin surveillance for 48 -72 hours postoperatively in patients with a >5% risk of major perioperative cardiovascular complications. This approach is cost-effective in SA. One in 10 patients with MINS dies within 30 days of surgery, and 1 in 5 develops major cardiovascular complications. Short-and long-term mortality could be improved by simple treatment strategies, including cardiovascular therapy intensification, and by ensuring aspirin use and statin therapy. All recommendations promote the involvement of a multidisciplinary team. MINS is a common, serious perioperative cardiovascular complication with public healthcare implications that has been underappreciated in SA. A multidisciplinary approach with simple treatment strategies should be adopted