An appraisal of different cardiac risk reduction strategies in vascular surgery patients

Nitrates for the prevention of cardiac morbidity and mortality in patients undergoing non-cardiac surgery

BACKGROUND

Cardiac complications are not uncommon in patients undergoing non-cardiac surgery, especially in patients with coronary artery disease (CAD) or at high risk of CAD. Perioperative cardiac complications can lead to mortality and morbidity, as well as higher costs for patient care. Nitrates, which are among the most commonly used cardiovascular drugs, perform the function of decreasing cardiac preload while improving cardiac blood perfusion. Sometimes, nitrates are administered to patients undergoing non-cardiac surgery to reduce the incidence of cardiac complications, especially for patients with CAD. However, their effects on patients' relevant outcomes remain controversial.

OBJECTIVES

• To assess effects of nitrates as compared with other interventions or placebo in reducing cardiac risk (such as death caused by cardiac factors, angina pectoris, acute myocardial infarction, acute heart failure and cardiac arrhythmia) in patients undergoing non-cardiac surgery.• To identify the influence of different routes and dosages of nitrates on patient outcomes.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and the Chinese BioMedical Database until June 2014. We also searched relevant conference abstracts of important anaesthesiology or cardiology scientific meetings, the database of ongoing trials and Google Scholar.We reran the search in January 2016. We added three potential new studies of interest to the list of 'Studies awaiting classification' and will incorporate them into our formal review findings for the review update.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) comparing nitrates versus no treatment, placebo or other pharmacological interventions in participants (15 years of age and older) undergoing non-cardiac surgery under any type of anaesthesia.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures as expected by Cochrane. Two review authors selected trials, extracted data from included studies and assessed risk of bias. We resolved differences by discussion and, when necessary, sought help and suggestions from a third review author. We used a random-effects model for data analysis.

MAIN RESULTS

We included 27 randomized controlled trials (RCTs) (8244 participants analysed). Investigators reported 12 different comparisons of three different nitrates (nitroglycerin, isosorbide dinitrate and nicorandil) versus no treatment, placebo or other pharmacological interventions. All participants were older than 15 years of age. More than half of the trials used general anaesthesia. Surgical procedures in most trials were at low to moderate risk for perioperative cardiac complications. Only two comparisons including three studies reported the primary outcome - all-cause mortality up to 30 days post operation. Researchers reported other morbidity outcomes and adverse events in a variable and heterogeneous way, resulting in limited available data for inclusion in the meta-analysis. We determined that the overall methodological quality of included studies was fair to low, in accordance with risk of bias in most domains.In summary, we found no difference in the primary outcome - all-cause mortality up to 30 days post operation - when nitroglycerin was compared with no treatment (one study, 60 participants, 0/30 vs 1/30; (risk ratio (RR) 0.33, 95% confidence interval (CI) 0.01 to 7.87, very low-quality evidence based on GRADE criteria) or with placebo (two studies, 89 participants, 1/45 vs 0/44; RR 2.81, 95% CI 0.12 to 63.83, very low-quality evidence). Regarding our secondary outcomes, we noted no statistically significant differences in angina pectoris, acute myocardial infarction, acute heart failure, cardiac arrhythmia or cardiac arrest in any comparisons. In comparisons versus nitroglycerin, although more events of cardiac ischaemia were observed in participants receiving no treatment or placebo, we found no statistically significant differences in any comparisons, except the comparison of nicorandil versus placebo. One study revealed a potential dose-dependent protective effect of nicorandil for cardiac ischaemia.Adverse events were reported in a heterogeneous way among the comparisons. In general, more participants treated with nitrates had hypotension, tachycardia and headache, but investigators reported no statistically significant differences between groups in any comparisons.

AUTHORS' CONCLUSIONS

This systematic review suggests that nitroglycerin or isosorbide dinitrate is not associated with improvement in mortality and cardiac complications among patients undergoing non-cardiac surgery. Limited evidence suggests that nicorandil may reduce the risk of cardiac ischaemia in participants undergoing non-cardiac surgery. Additional studies are needed to consolidate the evidence.However, the data included in many of the analyses in this review are sparse - that is, adequate data are few - resulting in very low power to detect differences between nitrates and comparators. Thus, a more objective conclusion would state that available evidence is insufficient to show whether nitrates are associated with improvement in mortality and cardiac complications among patients undergoing non-cardiac surgery.Over the past decade, no high-quality studies have focused on association of cardiac mortality and morbidity with use of nitrates during non-cardiac surgery. This review underlines the need for well-designed trials in this field.

Obesity and the orthopedic trauma patient: a review of the risks and challenges in medical and surgical management

The medical and surgical care of obese trauma patients presents a variety of unique and important challenges. Over the past 30 years, this population has increased dramatically in number, and the optimization of their care demands the attention of the medical community. The problems of caring for an obese trauma patient begin before the actual traumatic event occurs due to their substantially higher incidence of serious comorbidities, such as diabetes mellitus, hypertension, and cardiopulmonary issues. In the setting of trauma, important considerations for the obese patient include careful and expeditious preoperative medical optimization; appropriate deep vein thrombosis prophylaxis; planning for and preventing operative and postoperative challenges (eg, pulmonary and wound complications); and ensuring adequate hospital equipment and staffing resources in the acute and rehabilitative phases of care. This article outlines the scope of the obesity epidemic, reviews the medical consequences of obesity, and highlights surgical considerations specific to the care of orthopedic injuries in the obese trauma patient.

The effects of prophylactic coronary revascularization or medical management on patient outcomes after noncardiac surgery - a meta-analysis

PURPOSE

The benefits of prophylactic coronary revascularization for patients undergoing noncardiac surgery are uncertain. The purpose of this study was to systematically evaluate the effect of coronary revascularization and medical management on short- and long-term outcomes after noncardiac surgery.

METHOD

Ten electronic databases including MEDLINE and EMBASE (1980 to February 2006), and bibliographies of included articles were searched without language restrictions. Studies comparing effects of coronary revascularization and medical management before noncardiac surgery were included. Patient outcome data including perioperative mortality, myocardial infarction, long-term mortality, or late adverse cardiac events were extracted and entered into a meta-analysis.

RESULTS

The quality of published evidence was modest, comprising one randomized controlled trial and six retrospective studies. A total of 3,949 patients undergoing high-risk noncardiac surgery were included in the quantitative analysis. There was no significant difference between coronary revascularization and medical management groups with regards to postoperative mortality and myocardial infarction; the odds ratios (95% confidence intervals) were 0.85 (0.48-1.50) and 0.95 (0.44-2.08), respectively. There were no long-term outcome benefits associated with prophylactic coronary revascularization; the odds ratios (95% confidence intervals) were 0.81 (0.40-1.63) and 1.65 (0.70-3.86) for long-term mortality and late adverse cardiac events, respectively.

CONCLUSION

In patients with stable coronary artery disease, prophylactic coronary revascularization before high-risk noncardiac surgery does not confer any beneficial effects, when compared with optimized medical management, in terms of perioperative mortality, myocardial infarction, long-term mortality, or adverse cardiac events.

Abdominal Aortic Aneurysm Repair in Octogenarians: Outcomes and Predictors

OBJECTIVES

This study was undertaken to evaluate predictors and outcomes of octogenarians who underwent abdominal aortic aneurysm repair.

DESIGN

A prospective observational study.

MATERIALS AND METHODS

Between January 1st, 1997 and April 15th, 2005, 31 octogenarians were admitted to our Department with the diagnosis of abdominal aortic aneurysm. Mean follow-up time was 53.7+/-27.2 months. All patients were in good clinical condition and represented a selected healthy group of octogenarians.

RESULTS

The overall perioperative (30-days) mortality rate was 3.1%. The total in-hospital morbidity rate was 22.6%. Overall survival estimates at 48 and 96 months were 81+/-8% and 46+/-21%, respectively. The actuarial freedom from aneurysm-related death at 48 and 96 months was 96+/-4% and 96+/-4%, respectively. The actuarial freedom from aneurysm-unrelated death at 48 and 96 months was 84+/-7% and 48+/-21%. Only coronary artery disease was a significant predictor of survival using multivariate stepwise logistic regression analysis.

CONCLUSIONS

In this series, AAA surgery was carried out in selected octogenarians without affecting long-term survival.

Barriers to Implementing a Surgical Beta-Blocker Protocol

BACKGROUND

Experience with a quality improvement (QI) program undertaken to increase the use of beta-adrenergic blockade in at-risk patients at both a major academic medical center and a community hospital suggests barriers to implementation.

METHODS

A retrospective and prospective cohort study was performed to establish the incidence and effectiveness of beta-blockade use pre- and postimplementation of a standardized screening tool and a major education program as part of a QI project. Data gathering involved a baseline phase pre-intervention; 6 weeks postintervention; and 3-6 months postintervention.

RESULTS

During phase I (baseline) 56% of eligible received beta-blockers, but targeted measures (a pre-induction heart rate < 70 or a systolic blood pressure [BP] < 110 mmHg) were achieved in only 11% of patients. Phase II saw a significant overall increase in beta-blocker administration (79%) and efficacy (50%). However, during phase III (3-6 months postimplementation), the rate of beta-blocker administration fell to 61% overall, while overall efficacy remained stable at 52%. Significant differences between the academic and community hospitals were observed throughout the study.

CONCLUSION

Implementation of a quality program for beta-blockade is significantly affected by the presence or absence of ongoing physician and staff education beyond the study period.

Assessment and management of the obese patient

BACKGROUND

The perioperative care of the clinically severe obese patient presents numerous unique challenges. As an increasing number of people in North America fall into the category of the clinically severe obese, the care of these patients will become increasingly more challenging and prevalent. These patients have unique issues with regards to cardiovascular, pulmonary, and thromboembolic complications. In addition, hospital equipment must be able to accommodate the body habitus of this population.

MATERIALS AND METHODS

A Medline search using "perioperative care," "morbid obesity," "thromboembolic complications," "preoperative screening," and "postoperative care" as key words was performed for English-language articles. Further references were obtained through cross-referencing the bibliography cited in each work.

DISCUSSION

The management of the clinically severe obese patient requires meticulous preoperative, perioperative, and postoperative care. Careful preoperative planning is essential before taking the patient to the operating room. To have excellent outcomes, a multidisciplinary approach, including the primary care physician, anesthesiologist, surgeon, nursing staff, and social work, is necessary.

Vascular evaluation and arterial reconstruction of the diabetic foot

Findings of diminished or absent pulses, pallor on elevation, redness of the foot on lowering of the leg, sluggish refilling of the toe capillaries, and thickened nails or absence of toe hair are consistent with impaired arterial perfusion to the foot. When ischemia is recognized as contributing to pedal ulceration and infection in the diabetic foot, quantitation of its severity may be difficult. Standard clinical evaluation of trophic changes is limited in an infected foot with its accompanying swelling, edema, and erythema. A palpable pedal pulse does not preclude the possibility of the presence of limb-threatening ischemia. Additional non-invasive vascular studies should be undertaken for these patients. Management of the diabetic foot is often a complex clinical problem. However, the principles of care are simple, including correction of systemic factors, such as blood glucose control, cardiovascular risk factor management, and smoking, as well as local factor correction, such as debridement, pressure relief, infection control, and revascularization when indicated. When a patient presents with evidence of infection, adequate drainage and antibiotic therapy are mandatory. The next step should be performed to differentiate the more common neuropathic ulcerations from the truly ischemic ulceration. Symptoms of rest pain or claudication are not often helpful because many of these patients are asymptomatic as a result of the presence of their neuropathy and inactivity. If an infected foot requires debridement or open partial forefoot amputation, observing the wound on a daily base is also important. Once infection is eradicated, there should be prompt signs of healing, including the development of wound granulation within several days. If wounds are not showing signs of prompt healing, arteriography is necessary. Early aggressive drainage, debridement, and local foot amputations combined with liberal use of revascularization results in cumulative limb salvage of 74% at 5 years in high-risk groups. Others report that pedal bypass to the ischemic infected foot is effective and safe as long as infection adequately controlled. These studies strongly suggest that early recognition and aggressive surgical drainage of pedal sepsis followed by surgical revascularization is critical to achieving maximal limb salvage in the high-risk population. Patients who have diabetes present a unique challenge in lower extremity revascularization because of the distal origination of many bypasses, distal distribution of the occlusive disease, and the frequently calcified arterial wall. An aggressive multidisciplinary approach to foot disease associated with diabetes involving the primary care provider, medical specialists, interventional radiology, and podiatric, plastic, and vascular surgeons will provide optimal medical and surgical care. Peripheral vascular disease is highly treatable if intervention is instituted in a timely and collegial fashion.