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

No Abstract

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

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

A prospective study of paediatric preoperative fasting times at Red Cross War Memorial Children’s Hospital, Cape Town, South Africa

Background. Fasting for liquids and solids is recommended prior to procedures requiring anaesthesia, to reduce the risk of pulmonary aspiration. Children often experience excessive fasting, which is associated with negative physiological and behavioural consequences, and patient discomfort. The duration of preoperative fasting in children in South Africa (SA) is unknown.Objectives. To determine compliance with fasting guidelines and fasting times of children prior to elective procedures performed under anaesthesia at a paediatric hospital in Cape Town, SA. The primary focus was fasting for clear liquid. We also intended to identify the most common reasons for prolonged clear liquid fasting.Methods. Over a 7-week period, we prospectively captured fasting times of consecutive patients undergoing elective surgical, medical and radiological procedures at Red Cross War Memorial Children’s Hospital. Measurement outcomes were defined as the period from the last clear liquid, milk or solid feed to the start of anaesthesia. For analysis of compliance with preoperative fasting guidelines, institutional preoperative fasting target limits were established based on the standard 6-4-2-hour guideline.Results. The study included 721 elective paediatric cases. The mean (standard deviation (SD)) fasting time for clear liquids (n=585) was 8.0 (4.8) hours, with an adherence rate of 25.5% (95% confidence interval 22 - 29) to the institutional target of 2 - 4 hours. The mean (SD) fasting times for breastmilk (n=92), formula milk (n=116) and solid feeds (n=560) were 7.1 (2.8), 8.8 (2.8) and 13.9 (3.6) hours, respectively. The factors associated with clear liquid fasting >4 hours were inadequate fasting instructions, poor adherence to fasting orders, procedural delays and fasting to promote theatre flexibility.Conclusions. This study demonstrates that children in an SA hospital experience excessive fasting times prior to elective procedures. To reduce fasting durations and improve the quality of perioperative care, quality improvement interventions are required to create an adaptable fasting system that allows individualised fasting. Improving preoperative fasting times in children is the responsibility of all healthcare professionals in the multidisciplinary management team

Incidence of myocardial injury after non-cardiac surgery: Experience at Groote Schuur Hospital, Cape Town, South Africa

Background. Myocardial injury after non-cardiac surgery (MINS) is a newly recognised entity identified as an independent risk factor associated with increased 30-day all-cause mortality. MINS increases the risk of death in the perioperative period by ~10-fold. More than 80% of patients with MINS are asymptomatic, so the majority of diagnoses are missed. Awareness of MINS is therefore important for perioperative physicians.Objectives. To investigate the incidence of MINS after elective elevated-risk non-cardiac surgery at Groote Schuur Hospital, Cape Town, South Africa (SA).Methods. Patients aged ≥45 years undergoing elective elevated-risk non-cardiac surgery were enrolled via convenience sampling. The new fifth-generation high-sensitivity cardiac troponin T blood test was used postoperatively to identify MINS. Preoperative troponin levels were not measured.Results. Among 244 patients included in the study, the incidence of MINS was 4.9% (95% confidence interval (CI) 2.8 - 8.5), which was not significantly different from that in a major international prospective observational study (VISION) (8.0% (95% CI 7.5 - 8.4)); p=0.080.Conclusions. Our SA cohort had a lower cardiovascular risk profile but a similar incidence of MINS to that described in international literature. The impact of MINS on morbidity and mortality is therefore likely to be proportionally higher in SA than in published international studies. The limited sample size and lower event rate weaken our conclusions. Larger studies are required to establish patient and surgical risk factors for MINS, allowing for revision of cardiovascular risk prediction models in SA.

A multicentre cross-sectional descriptive study evaluating the cardiovascular risk profile of preoperatively identified patients with hypertension

Background. The prevalence of hypertension in adults in South Africa (SA) is 35%. Hypertension is the most important modifiable risk factor for cardiovascular (CV) and chronic kidney disease (CKD) in sub-Saharan Africa. However, 49% of people are unaware of their blood pressure status. Screening for hypertension prior to surgery provides a unique opportunity to diagnose and treat affected individuals. Furthermore, assessing overall CV risk identifies patients at highest risk for complications, and improves the utilisation of scarce resources. Objectives. To evaluate the CV risk profile of hypertensive patients in the adult population of the Western Cape Province presenting for elective non-cardiac, non-obstetric surgery. Methods. This report documents the CV risk profile of patients recruited to the HASS-2 study (Hypertension and Surgery Study 2), which was undertaken in seven Western Cape hospitals. Patients were screened for hypertension and pharmacological treatment was initiated or adjusted in patients with stages 1 and 2 disease. Stage 3 patients were referred to a physician. In the present substudy, patients with stages 1 and 2 hypertension were assessed for associated CV risk factors, the presence of target organ damage, and documented CV or kidney disease; they received an overall risk stratification according to the 2018 European Society of Cardiology and the European Society of Hypertension Guidelines. Results. Sixty-one patients with stage 1 and 12 with stage 2 hypertension were analysed. Established CV disease was present in 13.7% of the study population, and CKD (eGFR <60 mL/min) in 10.8%. Seventy-one percent of the study group had a raised body mass index, and 55.9% underlying metabolic syndrome. Prediabetes and diabetes were present in 16.1% and 14.5%, respectively. According to the 2018 European guidelines, 34.7% were at moderate, 33.3% at high and 16.7% at very high risk for a CV event in the following 10 years.Conclusions. The perioperative period is a critical time during which surgeons, nurses and anaesthetists can influence patients’ CV risk of adverse events. This involves appropriate screening, education and treatment. In this study population, nearly 9 out of 10 elective surgical patients with stage 1 or 2 hypertension had CV risk factors placing them at moderate to very high risk. The simultaneous assessment of these additional CV risk parameters, in addition to diagnosis and management of hypertension, may further decrease the health and financial burden in resource-limited facilities in SA, and improve CV outcomes.