Progress in perioperative medicine: focus on statins

Addressing the Global Burden of Trauma in Major Surgery

Despite a technically perfect procedure, surgical stress can determine the success or failure of an operation. Surgical trauma is often referred to as the "neglected step-child" of global health in terms of patient numbers, mortality, morbidity, and costs. A staggering 234 million major surgeries are performed every year, and depending upon country and institution, up to 4% of patients will die before leaving hospital, up to 15% will have serious post-operative morbidity, and 5-15% will be readmitted within 30 days. These percentages equate to around 1000 deaths and 4000 major complications every hour, and it has been estimated that 50% may be preventable. New frontline drugs are urgently required to make major surgery safer for the patient and more predictable for the surgeon. We review the basic physiology of the stress response from neuroendocrine to genomic systems, and discuss the paucity of clinical data supporting the use of statins, beta-adrenergic blockers and calcium-channel blockers. Since cardiac-related complications are the most common, particularly in the elderly, a key strategy would be to improve ventricular-arterial coupling to safeguard the endothelium and maintain tissue oxygenation. Reduced O2 supply is associated with glycocalyx shedding, decreased endothelial barrier function, fluid leakage, inflammation, and coagulopathy. A healthy endothelium may prevent these "secondary hit" complications, including possibly immunosuppression. Thus, the four pillars of whole body resynchronization during surgical trauma, and targets for new therapies, are: (1) the CNS, (2) the heart, (3) arterial supply and venous return functions, and (4) the endothelium. This is termed the Central-Cardio-Vascular-Endothelium (CCVE) coupling hypothesis. Since similar sterile injury cascades exist in critical illness, accidental trauma, hemorrhage, cardiac arrest, infection and burns, new drugs that improve CCVE coupling may find wide utility in civilian and military medicine.

Moderate Aortic Stenosis and Coronary Artery Bypass Grafting: Clinical Update for the Perioperative Echocardiographer

Incidental aortic stenosis in the setting of coronary artery bypass surgery may be a perioperative challenge. The accurate assessment of the degree of aortic stenosis remains an important determinant. Although severe aortic stenosis is an indication for valve replacement, current guidelines advise a balanced approach to the management of moderate aortic stenosis in this setting. Multiple factors should be considered in a team discussion to balance risks versus benefits for the various management options in the given patient. The rapid progress in aortic valve technologies also offer alternatives for definitive management of moderate aortic stenosis in this setting that will likely become even safer in the near future.

The effects of preoperative renin-angiotensin system inhibitors on outcomes in patients undergoing cardiac surgery

OBJECTIVE

The effects of preoperative (pre-op) renin-angiotensin system (RAS) inhibitors on outcomes in patients undergoing cardiac surgery remain uncertain. The aim of this study was to evaluate whether the use of pre-op RAS inhibitors affected major outcomes of cardiac surgery.

DESIGN

A retrospective cohort study.

SETTING

A university teaching hospital.

PARTICIPANTS

Patients undergoing cardiac surgery between January 1, 2001 and December 31, 2011.

INTERVENTIONS

One thousand two hundred thirty-nine patients who received pre-op RAS inhibitors were compared with those who did not (control group, n = 1,083).

MEASUREMENTS AND MAIN RESULTS

Acute kidney injury (AKI) was defined using Acute Kidney Injury Network classification. Patients in the RAS inhibitors group presented with higher comorbidities. Pre-op RAS inhibitors therapy was associated with the reduction in the incidence of AKI (27.2% v 34.0%, p<0.001), septicemia (1.9% v 3.5%, p = 0.019), and operative mortality (2.99% v 4.62%, p = 0.039). After adjusted propensity scores and multivariate logistic regression, the pre-op RAS inhibitors were found to have protective effects against AKI (odds ratio [OR]: 0.764, 95% confidence interval [CI]: 0.670-0.873, p<0.001), septicemia (OR: 0.515, 95% CI: 0.348-0.761, p>0.001), and operative mortality (OR: 0.539, 95% CI: 0.348-0.758, p<0.001).

CONCLUSION

The results suggested that pre-op RAS inhibitor therapy was associated with significant reductions in the risk of AKI, operative mortality, and septicemia.

Integrating outcome benefit into anesthetic design: the promise of steroids and statins

Steroids and statins may facilitate the integration of anesthetic design with clinical outcome. Although steroids clearly benefit adult cardiac surgical patents, the evidence is weaker in pediatric cardiac surgery. Current large randomized trials of steroids likely will determine the future role of steroids in adult cardiac surgery. In the intensive care unit, steroid therapy is indicated in septic shock that is refractory to fluid and pressor therapy. Recent data, however, indicate that liberal steroid therapy for sepsis may have adverse outcome consequences. A 2nd concern in the intensive care unit is acute adrenal suppression secondary to bolus etomidate therapy because it may be deleterious in patients with septic shock. Possible clinical solutions include alternative induction agents, concomitant steroid therapy, and recent etomidate derivatives. Statins also reduce mortality and atrial fibrillation after cardiac surgery. Furthermore, they slow the progression of rheumatic valvular stenosis, an important consideration in the developing world. Statins also may reduce delirium, stroke, and acute renal injury after cardiac surgery, but further randomized trials are required before definitive recommendations can be formulated. Statins are essential in vascular surgery because they reduce mortality, myocardial ischemia, and acute renal injury. As a result, they have been recommended highly for outcome enhancement in recent perioperative guidelines. Although they may improve survival in sepsis, further investigation is indicated to define their therapeutic role.

[Acute postoperative confusional syndrome in the elderly patient]

With the progressive aging of the population surgical candidates have more comorbidities resulting in a higher risk to develop postoperative complications. One of the most frequent postoperative complications in the elderly is acute confusional state or delirium, which may have devastating consequences: higher mortality, and risk of medical complications during admission and, a higher risk of functional decline, institutionalization, and cognitive impairment at discharge. For all these reasons and with the aim of optimising surgical procedures, it is essential to identify patients at risk of delirium in order to take appropriate preventive action and provide early treatment. In the present article we review the current evidence on the management of postoperative delirium in the elderly.

Innovations in treating aortic diseases: the abdominal aorta

Patients with an abdominal aortic aneurysm (AAA) could benefit from earlier diagnosis to improve long-term outcomes. Candidate serum biomarkers for earlier AAA diagnosis include D-dimer, fibrinogen, low-density lipoprotein, high-density lipoprotein, lipoprotein(a), and the proteolytic enzymes known as matrix metalloproteinases. Furthermore, biomarkers such as brain natriuretic peptide significantly stratify perioperative risk in AAA repair. Statins significantly improve outcomes after AAA repair. They may also significantly slow AAA growth to allow pharmacologic arrest of AAA development. Recent trials have focused attention on fluid management for AAA repair. Although restrictive fluid management may significantly improve clinical outcomes, current evidence does not clearly support crystalloid or colloid for AAA repair. There may be an increased risk of renal dysfunction associated with hetastarch therapy. Endovascular repair has revolutionized the clinical management of AAAs. Recent trials have shown its significant outcome advantages. Furthermore, it is also applicable in high-risk operative cohorts and, in the future, may be suited for earlier AAA repair. This technology continues to advance with the development of branched and fenestrated grafts as well as total percutaneous endovascular AAA repair. Regardless of these advances, the clinical management of endoleaks will remain a major clinical focus. Taken together, these advances in the management of AAAs likely will significantly influence future clinical approaches to this challenging patient cohort.