Proactive Risk Assessment through Failure Mode and Effect Analysis (FMEA) for Perioperative Management Model of Oral Anticoagulant Therapy: A Pilot Project

INTRODUCTION

Correct perioperative management of anticoagulant therapy is essential to prevent thromboembolic events and reduce the risk of bleeding. The lack of universally accepted guidelines makes perioperative anticoagulant therapy management difficult. The present study aims to identify the perioperative risks of oral anticoagulant therapy and to reduce adverse events through Failure Mode and Effect Analysis (FMEA).

MATERIALS AND METHODS

A multidisciplinary working group was set up, and four main phases of the process were identified. Each of these phases was divided into micro-activities to identify the related possible failure modes and their potential consequences. The Risk Priority Number was calculated for each failure mode.

RESULTS AND DISCUSSION

Seventeen failure modes were identified in the entire perioperative period; those with a higher priority of intervention concern the incorrect timing between therapy suspension and surgery, and the incorrect assessment of the bleeding risk related to the invasive procedure.

CONCLUSION

The FMEA method can help identify anticoagulant therapy perioperative failures and implement the management and patient safety of surgical procedures.

Proactive Risk Assessment Through Failure Mode and Effect Analysis (FMEA) for Haemodialysis Facilities: A Pilot Project

Haemodialysis (HD) is one of the methods for renal replacement therapy in the management of advanced chronic kidney disease through an osmosis process that allows purification of blood in the dialysis machine. The complexity of the dialytic procedure often requires the presence of a multi-specialist, multi-disciplinary team. The dialysis process is an important target for clinical risk management. Failure Mode and Effect Analysis (FMEA) is a proactive technique, considered a purposeful and dynamic tool for clinical risk management. FMEA is noted in five phases that allow a preliminary assessment of a definite process through identification and classification of risk priorities. This study represents the first of a two-phase project where FMEA is applied to HD in the setting of San Feliciano Hospital. The dialysis center performs ~12,000 dialysis sessions per year. The dialysis process is divided into different stages. A total of 31 failure modes were identified in the whole dialysis stages; more than 2/3 of the failure modes were related to the only connecting of the patient to the dialysis machine. The first phase of the study clearly remarked that the most critical step of the dialytic process is represented by the connection between the patient and the machine, as expected. Indeed, in order to have the dialysis set up, an arteriovenous fistula must be surgically created prior to the procedure and it is one of the most important issues in the HD process because of the necessity of a constant revision of it. FMEA application to HD is a useful tool, easy to be implemented and it is likely to nimbly reveal the practical and potential solutions to the critical steps of the procedure.

Vitamin E, Atherosclerosis and Thrombosis

Vitamin E, a major lipid-soluble, chain-breaking antioxidant includes several tocopherols having the biological activity of RRR-alpha-tocopherol. Vitamin E circulates in the blood as free tocopherol bound to beta-lipoproteins and is present in cell membrane where it exerts a potent defence against lipid peroxidation (1). Blood concentration of vitamin E in humans ranges from 25 to 30 μM, depending on daily intake and body’s ability to absorb fat (1). In the last decade the scientific interest on biological activity of vitamin E increased because of a growing body of evidence linking this vitamin with atherosclerosis and its complications (2). Thus, the oxidative hypothesis of atherosclerosis suggests that LDL accumulates within vessel wall, in particular in the macrophages, as a consequence of its oxidative modification mediated by resident cells (3, 4). A reduced defence against LDL oxidation could favour this process and accelerate atherosclerotic progression. Accordingly, patients with coronary heart disease have lower plasma concentration of vitamin E than controls (2) and prospective studies demonstrated that a daily assumption of vitamin E reduces cardiovascular events (5). According to the oxidative hypothesis of atherosclerosis, this effect has been attributed to the inhibition of LDL oxidation. Alternative mechanism potentially implicated in the antiatherosclerotic activity of vitamin E includes its interference with the activity of platelet and monocyte, in which the intracellular redox status plays an important functional role (6, 7). As platelets and monocytes are both involved in the pathophysiologic process leading to atherosclerotic lesion, the interference of vitamin E with the biological function of these cells may represent another important tool to explore the anti-atherosclerotic activity of vitamin E. This review will focus on the open issues related to the use of vitamin E in clinical studies and the potential usefulness in investigating platelet function and clotting activation in patients treated with vitamin E.

Increased plasma levels of oxysterols, in vivo markers of oxidative stress, in patients with familial combined hyperlipidemia: reduction during atorvastatin and fenofibrate therapy

Familial combined hyperlipidemia (FCHL), the most common inherited disorder of lipid metabolism, is associated with an increased risk of atherosclerosis that is not fully explained by the metabolic disturbances of these patients. Oxidative damage to lipid components accumulating in the plasma of FCHL patients might contribute to explaining this lack of evidence. Cholesterol is one of the preferential targets of oxidation in LDL and this may contribute to setting a proatherogenetic phenotype in FCHL. We investigated plasma oxysterols (7-ketocholesterol and 7beta-hydroxycholesterol) and alpha-tocopherol as in vivo hallmarks of lipid-related oxidative stress. Oxidative stress hallmarks were measured in 45 FCHL patients and 54 sex- and age-matched healthy controls; in FCHL patients, oxidative stress and lipid profile parameters were also assessed in response to lipid-lowering drugs in a 24-week randomized, open-label trial with atorvastatin or fenofibrate. FCHL patients showed markedly increased levels of oxysterols (p < 0.001) and reduced alpha-tocopherol/total lipids (p < 0.001) compared to controls. These differences were independent of the presence of clinical atherosclerosis and persisted after correction for hyperlipidemia. Atorvastatin and fenofibrate significantly improved the lipid profile and caused a comparable decrease in plasma oxysterols, with the normalization of 7-ketocholesterol and a significant reduction of 7beta-hydroxycholesterol (p < 0.001). These drugs also decreased the ratio of alpha-tocopherol/total lipids by more than 30% (p < 0.001). In conclusion, FCHL patients showed increased hallmarks of cholesterol oxidation and decreased levels of alpha-tocopherol/total lipids. Atorvastatin and fenofibrate displayed comparable efficiency in decreasing oxysterols, but they further decreased lipid-corrected alpha-tocopherol levels in plasma. More research work is needed to understand the clinical meaning of these findings, which may help to understand the role of oxidative stress in FCHL and lipid-lowering therapy.

High preoperative recipient plasma 7beta-hydroxycholesterol is associated with initial poor graft function after liver transplantation

Oxidative stress is implicated in the pathogenesis of hepatic ischemia-reperfusion injury, a major determinant of initial poor graft function (IPGF) after orthotopic liver transplantation (OLT). We prospectively investigated the association between the recipient plasma preoperative oxidative stress and the occurrence of IPGF after deceased-donor OLT and indirectly studied the source-hepatic or extra-hepatic-of systemic oxidative stress in vivo in cirrhosis. We used a recently developed specific and sensitive mass spectrometry assay to measure 7beta-hydroxycholesterol and 7-ketocholesterol (oxysterols), markers of oxidative stress, in biological matrices. At univariate analysis, preoperative recipient 7beta-hydroxycholesterol plasma concentration was significantly higher in transplants with subsequent IPGF (n = 9) compared with those with initial good graft function (IGGF; n = 23) [mean +/- SD: 30.63 +/- 26.42 and 11.57 +/- 15.76 ng/mL, respectively] (P = 0.017). In a logistic regression model, which included also the Model for End-Stage Liver Disease (MELD) score, 7beta-hydroxycholesterol plasma concentration was an independent predictor of IPGF with an odds ratio of 1.17 (95% CI, 1.02-1.33, P = 0.028). Patients with cirrhosis (n = 32) had increased oxysterol plasma levels compared with healthy controls (n = 49); livers with cirrhosis (n = 21), however, had oxysterol content comparable with normal livers obtained from organ donors (n = 19). Oxysterols persisted elevated in plasma 1 month after OLT (n = 23). In conclusion, cirrhosis presents upregulated systemic oxidative stress likely of extrahepatic source that is associated with graft failure after OLT.

Baseline Oxysterols and Other Markers of Oxidative Stress, Inflammation and Malnutrition in the Vitamin E and Intima Media Thickness Progression in End-Stage Renal Disease (VIPER) Cohort

BACKGROUND AND OBJECTIVES

Oxysterols are markers of oxidative stress, levels of which have not yet been reported in hemodialysis (HD) patients. This study was designed to compare levels of the oxysterols 7-ketocholesterol (7KC) and 7beta-hydroxycholesterol (7betaOH) between a cohort of HD patients and healthy controls.

METHODS

This nested cross-sectional study reflects baseline (pre-intervention) values for markers of oxidative stress, inflammation and nutrition status in the 160-member vitamin E and carotid intima media thickness progression in end-stage renal disease (VIPER) cohort (age 64.1 +/- 8.8, 33.5% female). Age- and sex-matched healthy volunteers served as controls. Plasma oxysterols 7KC and 7betaOH were determined by isotope dilution gas chromatography/mass spectrometry.

RESULTS

Despite higher plasma alpha-tocopherol levels in HD patients than controls (36.0 +/- 9.3 vs. 31.8 +/- 8.4 micromol/l, p = 0.007), 7KC levels (9.8 +/- 6.9 vs. 5.9 +/- 2.8 nmol/mmol cholesterol, p < 0.0001) and 7betaOH levels (8.7 +/- 4.3 vs. 2.7 +/- 1.6 nmol/mmol cholesterol, p < 0.0001) were higher in HD patients. The oxysterol 7betaOH was significantly, inversely associated with prealbumin (r = -0.18, p = 0.03), though neither oxysterol was significantly associated with any other marker of oxidative stress, inflammation or nutrition status and did not discriminate for CVD in HD patients.

CONCLUSIONS

Elevated levels of the oxysterols 7KC and 7betaOH indicate that HD patients are in a state of oxidative stress compared to healthy controls. However, oxysterols 7KC and 7betaOH did not appear to contribute additional information about oxidative stress among HD patients.

Vitamin E Supplementation in Patients With Carotid Atherosclerosis

OBJECTIVE

Oxidative stress is believed to play a pivotal role in the initiation and progression of atherosclerosis. We analyzed whether vitamin E supplementation influences oxidative stress in plasma and atherosclerotic plaques of patients with severe atherosclerosis.

METHODS AND RESULTS

In 16 patients who were candidates for carotid endarterectomy and in 32 age- and sex-matched controls, plasma levels of 7beta-hydroxycholesterol, 7-ketocholesterol, cholesterol, and vitamin E were measured. Patients were randomly allocated to standard treatment with or without 900 mg/d vitamin E. After 6 weeks of treatment, the reported variables were measured in plasma and plaques. The plasma vitamin E/cholesterol ratio was significantly lower in patients than in controls (3.05+/-0.6 versus 6.3+/-1.7 micromol/mmol cholesterol, P<0.001). Plasma 7beta-hydroxycholesterol was significantly higher in patients than in controls (5.0+/-1.04 versus 4.4+/-0.6 ng/mL, P<0.05). Patients who were given vitamin E supplementation showed a significant increase of plasma vitamin E with concomitant decrease of 7beta-hydroxycholesterol. Conversely, no treatment dependence was observed in oxysterol or vitamin E content of plaques.

CONCLUSIONS

An imbalance between oxidative stress and antioxidant status is present in patients with advanced atherosclerosis. Vitamin E supplementation improves this imbalance in plasma but not in plaques.

Measurement of oxysterols and alpha-tocopherol in plasma and tissue samples as indices of oxidant stress status

Oxidant stress seems to play a role in several setting of human pathology, such as atherosclerosis, cancer, and aging. The study of oxidant stress in human disease should be based on the evaluation of either sensitive and specific markers of enhanced oxidant stress, such as oxysterols, or antioxidant defense, by measuring alpha-tocopherol. We have developed a rapid method to measure the oxysterols 7beta-hydroxycholesterol and 7-ketocholesterol in plasma (50 healthy subjects) and tissue as an index of oxidant stress in vivo, and from the same sample alpha-tocopherol content. The mean plasma concentration of 7beta-hydroxycholesterol and 7-ketocholesterol was 4.6+/-1.1 and 13.4+/-7.6 ng/mL, respectively. Plasma alpha-tocopherol concentration was 5.8+/-1.0 micromol/mol cholesterol. Samples from atherosclerotic plaques contained 20 times more cholesterol, about 45 times higher oxysterols levels, and 600 times more alpha-tocopherol compared to normal arteries. No significant difference in cholesterol and oxysterol content was observed between cirrhotic and normal liver. However, cirrhotic liver contained significantly smaller concentration of alpha-tocopherol compared to normal liver. In conclusion, we have developed a rapid and reliable method for the assay of cholesterol oxidation products and alpha-tocopherol in plasma and tissue useful for estimation of oxidant stress/antioxidant balance.

Low-density lipoprotein oxidation

Free radical mediated oxidation of low-density lipoproteins (LDL), which has been extensively studied in the last two decades, plays a central role in the development of the atherosclerotic plaque. Oxidation involves the lipid moiety of LDL in a chain reaction mechanism. In the initial phase, free radicals preferentially attack highly oxidizable polyunsaturated fatty acids. Subsequent recruitment of other molecules includes cholesterol and phospholipids. The process of oxidation is counteracted by antioxidants present in LDL. By-products formed during oxidation of LDL lipids, which may have biological activity, react with amino acid residues of the LDL protein backbone with the consequent modification of chemical and immunological properties responsible for cellular receptor shift. Oxidation-altered apolipoprotein B of oxidized LDL is, in fact, recognized by the macrophage scavenger receptor responsible for foam cell formation. The mechanism of LDL oxidation and the impact on atherogenesis are discussed.

Bioavailability of vitamin E as function of food intake in healthy subjects: effects on plasma peroxide-scavenging activity and cholesterol-oxidation products

Clinical trials with vitamin E have yielded contrasting results. In these trials, the amount of vitamin E given was different, and the compliance was not assessed in all studies. In addition, the modality of intake, ie, in relation to food, was not specified in any trial. Vitamin E is lipophilic, and its absorption is expected to be increased by food. We studied the bioavailability of vitamin E in relation to food intake and the effect on the lipid peroxide-scavenging activity of plasma and on 7beta-hydroxycholesterol and 7-ketocholesterol (oxysterols) as markers of oxidant stress. Twenty healthy Italian subjects were randomly assigned to take vitamin E at 300 mg/d on an empty stomach (group A) or during dinner (group B) for 15 days. Plasma vitamin E markedly increased in group B (84%) compared with group A (29%). The lipid peroxide-scavenging activity of plasma increased significantly in group B (14%, P=0.005) but did not change in group A. All subjects showed very low levels of plasma oxysterols, which were not affected by vitamin E supplementation in either group. This study shows that plasma concentration of vitamin E and plasma antioxidant activity in response to oral supplementation are markedly affected by food intake. Healthy Italian subjects show very low levels of cholesterol oxidation products; these low levels are possibly related to the Mediterranean diet. To obtain maximal absorption, vitamin E must be given at meals. These data should be taken into account in clinical trials with vitamin E.

Fluorescence quenching of dipyridamole associated to peroxyl radical scavenging: a versatile probe to measure the chain breaking antioxidant activity of biomolecules

Dypiridamole is a highly efficient chain breaking antioxidant (Iuliano et al., Free Radic. Biol. Med. 18 (1995) 239-247) with an aromatic ring system responsible for an intense absorption band in the 400-480-nm region and for an intense fluorescence. Dipyridamole fluorescence is quantitatively quenched upon reaction with peroxyl radicals. In the presence of a flux of peroxyl radicals generated by thermal dissociation of azo-initiators, dipyridamole fluorescence decays linearly, showing a first-order reaction with respect to peroxyl radicals, and zero-order with respect to dipyridamole. The pH optimum for the fluorescence quenching is in the 7-8 range, from pH 7 to 6, the decay of fluorescence rapidly decreases to became negligible below pH 5.5. Dipyridamole consumption is blocked in the presence of an added chain breaking antioxidant for a time that is proportional to the antioxidant concentration. This effect is shown for ascorbic acid, trolox, vitamin E, uric acid, and N, N'-diphenyl-p-phenylenediamine. The slope of the linear correlation relative to trolox allows calculation of the bimolecular rate constant for a given molecule and peroxyl radicals. Comparison of data obtained by the dipyridamole consumption are comparable to values obtained by the oxygen consumption method.