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

Impact of oral meloxicam administered alone or in combination with gabapentin on experimentally induced lameness in beef calves

This study examined the pharmacokinetics and analgesic effect of oral meloxicam (MEL) administered alone or in combination with gabapentin (GABA) in an experimental bovine lameness model. Eighteen male British × Continental beef calves aged 4 to 6 mo and weighing 297 to 392 kg were randomly assigned to receive either 1) 0.5 mg/kg lactose monohydrate placebo (PLBO; n = 6), 2) 0.5 mg/kg MEL (n = 6), or 3) 0.5 mg/kg MEL combined with 15 mg/kg GABA (MEL-GABA; n = 6) once daily for 4 d. The first treatment was administered 4 h after a chemical synovitis/arthritis was induced with injection of 15 mg amphotericin B into the left hind lateral distal interphalangeal joint. Changes in activity were evaluated continuously with pedometers. Contact force, contact area, contact pressure, impulse, and stride length were recorded once daily with a pressure mat and visual lameness scores were determined by a masked observer using a 5-point scale. Cortisol and drug concentrations were determined daily by immunoassay and HPLC-mass spectrometry, respectively. Outcomes were compared statistically using a random effects mixed model and analysis of covariance. There was a positive association between lameness scores and serum cortisol concentrations (P = 0.02) and a negative association between lameness score and step count (P \u3c 0.0001), total force (P = 0.001), force applied to the lateral claw (P= 0.02), contact pressure (P = 0.005), and impulse of the lateral claw (P = 0.01). Step count was greater in MEL calves compared with PLBO (P = 0.008) and MEL-GABA (P = 0.04) calves. Impulse was greater in the MEL-GABA calves compared with the PLBO calves (P = 0.03). There was an inverse relationship between plasma MEL concentrations and lameness score (P = 0.02) and a positive association between MEL concentrations and force applied to the lateral claw (P = 0.03), total contact pressure (P = 0.03), and impulse on the lateral claw (P = 0.02). There was a tendency towards a positive association between GABA concentrations, total impulse, and impulse on the lateral claw (P = 0.08) and a negative associate between GABA concentrations and step count (P = 0.08). The results of this study suggest that MEL administered alone or in combination with GABA reduced the severity of lameness in calves following induction of lameness with amphotericin B. These findings have implications for developing analgesic protocols in lame calves that address both production and welfare concerns

Improving primary care antimicrobial stewardship by implementing a peer audit and feedback intervention in Cape Town community healthcare centres

Background. The increasing prevalence of antibiotic resistance is a major threat to public health. Primary care, where 80% of antibiotics are consumed, is a pivotal setting to direct antimicrobial stewardship (AMS) efforts. However, the ideal model to improve antibiotic prescribing in primary care in low-resource settings is not known.Objective. To implement a multidisciplinary audit and feedback AMS intervention with the aim to improve appropriate antibiotic prescribing at primary care level.Methods. The intervention was implemented and monitored in 10 primary care centres of the Cape Town metropole between July 2017 and June 2019. The primary and secondary outcome measures were monthly adherence to a bundle of antibiotic quality process measures and monthly antibiotic consumption, respectively. Multidisciplinary audit and feedback meetings were initiated and integrated into facility clinical meetings. Two Excel tools were utilised to automatically calculate facility audit scores and consumption. Once a month, 10 antibiotic prescriptions were randomly selected for a peer review audit by the team. The prescriptions were audited for adherence to a bundle of seven antibiotic process measures using the standard treatment guidelines (STG) and Essential Medicines List (EML) as standard. Concurrently, primary care pharmacists monitored monthly antibiotic consumption by calculating defined daily doses (DDDs) per 100 prescriptions dispensed. Adherence and consumption feedback were regularly provided to the facilities. Learning collaboratives involving representative multidisciplinary teams were held twice-yearly. Pre-, baseline and post-intervention periods were defined as 6 months before, first 6 months and last 6 months of the study, respectively.Results. The mean overall adherence increased from 19% (baseline) to 47% (post intervention) (p<0.001). Of the 2 077 prescriptions analysed, 33.7% had an antibiotic prescribed inappropriately. No diagnosis had been captured in patient notes, and the antibiotic chosen was not according to the STG and EML in 30.1% and 31.7% of cases, respectively. Seasonal variation was observed in prescribing adherence, with significantly lower adherence in winter and spring months (adjusted odds ratio 0.60). A reduction of 12.9 DDDs between the pre- and post-intervention periods (p=0.0084) was documented, which represented a 19.3% decrease in antibiotic consumption.Conclusion. The study demonstrated that peer reviewed audit and feedback is an effective AMS intervention to improve antibiotic prescribing in primary care in a low-resource setting. The intervention, utilising existing resources and involving multidisciplinary engagement, may be incorporated into existing quality improvement processes at facility level, to ensure sustainable change

Antibiotic prescribing practices in the presence of Extended-spectrum β-lactamase (ESBL) positive organisms in an adult intensive care unit in South Africa – a pilot study

Introduction: Antimicrobial resistance is one of the most severe health threats globally. Extended spectrum β-lactamases (ESBLs) are enzymes produced by a variety of gram-negative bacteria, which lead to an increase in resistance to commonly used antibiotics and are associated with higher morbidity and mortality. Objectives: Assess the prescribing practices prior to, and after, positive ESBL producing microbiology cultures in an adult ICU setting, according to sensitivity reports obtained from the clinical laboratories from January 2013 until January 2014. Subsequently use the findings to guide future practice. Method: Retrospective study at a private hospital in Pretoria, Gauteng Province. All adult patients older than 18 years of age that were admitted to either the MICU or the TICU with a positive producing ESBL culture during their hospitalised stay were assessed. Results: During the study period, 39 patients in the MICU and TICU had positive ESBL microbiology results. The majority of positive ESBL results were due to Klebsiella pneumonia isolates. Antibiotics prescribed post ESBL positive culture were appropriate according to the sensitivity report in 64% of patients. 22 patients survived and 17 patients died. All the patients that died were on invasive ventilatory support. Conclusion: Clinically it appears as if patients who received appropriate therapy according to the microbiology results showed a better clinical outcome than those with inappropriate therapy. This underlines the importance of appropriate prescribing practices in combination with co-morbid conditions. Invasive ventilatory support can be identified as a clear risk for contracting an infection due to an ESBL producing organism

Wind tunnel testing of a high aspect ratio wing model

There is much current interest in the development of High Aspect Ratio Wing (HARW) designs for improved aircraft performance. However, there are a lack of relevant data sets available to validate aeroelastic modelling approaches for highly flexible wings. The design and manufacture of a highly flexible 2.4m semi-span wing is described. A series of low speed wind tunnel tests were performed to generate displacement, acceleration, strain gauge, aerodynamic pressure and six component balance measurements for a range of airspeeds and wing root angles of attack. Numerous static and dynamic measurements were made. Preliminary results are shown for the static and dynamic, structural and aerodynamic behaviour over a range of different airspeeds and wing root angles of attack.Peer ReviewedPostprint (published version

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 prospective observational study of preoperative natriuretic peptide testing in adult non-cardiac surgical patients in hospitals in Western Cape Province, South Africa

Background. International guidelines recommend risk stratification to identify high-risk non-cardiac surgical patients. It is also recommended that all patients aged ≥45 years with significant cardiovascular disease should have preoperative natriuretic peptide (NP) testing. Abnormal preoperative B-type NPs have a strong association with postoperative cardiac complications. In South African hospitals, it is not known how many patients with significant cardiovascular disease scheduled for intermediate- to high-risk surgery will have raised NPs.Objectives. To determine the prevalence of abnormal (raised) NPs in non-cardiac surgical patients with cardiac clinical risk factors. A secondary objective was to develop a model to identify surgical patients who may benefit from preoperative NP screening.Methods. The inclusion criteria were patients aged ≥45 years presenting for elective, non-obstetric, intermediate- to high-risk non-cardiac surgery with at least one of the following cardiovascular risk factors: a history of ischaemic heart disease or peripheral vascular disease (coronary equivalent); a history of stroke or transient ischaemic attack; a history of congestive cardiac failure; diabetes mellitus currently on an oral hypoglycaemic agent or insulin; and serum creatinine level >175 µmol/L (>2.0 mg/dL). Blood samples for N-terminal-prohormone B-type NP (NT-proBNP) were collected before induction of anaesthesia. The preoperative prognostic threshold for abnormal (raised) NT-proBNP was ≥300 pg/mL. A generalised linear mixed model was used to determine the association between the risk factors and an abnormal NT-proBNP level.Results. Of 172 patients, 63 (37%) had an elevated preoperative NT-proBNP level. The comorbidities independently associated with elevated preoperative NT-proBNP were coronary artery disease or peripheral vascular disease, congestive cardiac failure, diabetes mellitus, and a creatinine level >175 µmol/L.Conclusions. We strongly recommend that non-cardiac surgical patients aged ≥45 years undergoing intermediate- or high-risk non-cardiac surgery with a history of coronary artery disease/peripheral vascular disease, congestive cardiac failure, diabetes mellitus or elevated creatinine have preoperative NP testing as part of risk stratification