Hemodynamic Modeling of the Intrarenal Circulation

Three dimensional, time dependent numerical simulations of healthy and pathological conditions in a model kidney were performed. Blood flow in a kidney is not commonly investigated by computational approach, in contrast for example, to the flow in a heart. The flow in a kidney is characterized by relatively small Reynolds number (100 < Re < 0.01-laminar regime). The presented results give insight into the structure of such flow, which is hard to measure in vivo. The simulations have suggested that venous thrombosis is more likely than arterial thrombosis-higher shear rate observed. The obtained maximum velocity, as a result of the simulations, agrees with the observed in vivo measurements. The time dependent simulations show separation regimes present in the vicinity of the maximum pressure value. The pathological constriction introduced to the arterial geometry leads to the changes in separation structures. The constriction of a single vessel affects flow in the whole kidney. Pathology results in different flow rate values in healthy and affected branches, as well as, different pulsate cycle characteristic for the whole system.

Reciprocal relationship between left ventricular filling pressure and the recruitable human coronary collateral circulation

AIMS The aim of our study in patients with coronary artery disease (CAD) and present, or absent, myocardial ischaemia during coronary occlusion was to test whether (i) left ventricular (LV) filling pressure is influenced by the collateral circulation and, on the other hand, that (ii) its resistance to flow is directly associated with LV filling pressure. METHODS AND RESULTS In 50 patients with CAD, the following parameters were obtained before and during a 60 s balloon occlusion: LV, aortic (Pao) and coronary pressure (Poccl), flow velocity (Voccl), central venous pressure (CVP), and coronary flow velocity after coronary angioplasty (V(Ø-occl)). The following variables were determined and analysed at 10 s intervals during occlusion, and at 60 s of occlusion: LV end-diastolic pressure (LVEDP), velocity-derived (CFIv) and pressure-derived collateral flow index (CFIp), coronary collateral (Rcoll), and peripheral resistance index to flow (Rperiph). Patients with ECG signs of ischaemia during coronary occlusion (insufficient collaterals, n = 33) had higher values of LVEDP over the entire course of occlusion than those without ECG signs of ischaemia during occlusion (sufficient collaterals, n = 17). Despite no ischaemia in the latter, there was an increase in LVEDP from 20 to 60 s of occlusion. In patients with insufficient collaterals, CFIv decreased and CFIp increased during occlusion. Beyond an occlusive LVEDP > 27 mmHg, Rcoll and Rperiph increased as a function of LVEDP. CONCLUSION Recruitable collaterals are reciprocally tied to LV filling pressure during occlusion. If poorly developed, they affect it via myocardial ischaemia; if well grown, LV filling pressure still increases gradually during occlusion despite the absence of ischaemia indicating transmission of collateral perfusion pressure to the LV. With low, but not high, collateral flow, resistance to collateral as well as coronary peripheral flow is related to LV filling pressure in the high range.

Ease of Application of Medical Compression-stocking Systems for the Treatment of Venous Ulcers

OBJECTIVE: To evaluate the ease of application of two-piece, graduated, compression systems for the treatment of venous ulcers. METHODS: Four kits used to provide limb compression in the management of venous ulcers were evaluated. These have been proven to be non-inferior to various types of bandages in clinical trials. The interface pressure exerted above the ankle by the under-stocking and the complete compression system and the force required to pull the over-stocking off were assessed in vitro. Ease of application of the four kits was evaluated in four sessions by five nurses who put stockings on their own legs in a blinded manner. They expressed their assessment of the stockings using a series of visual analogue scales (VASs). RESULTS: The Sigvaris Ulcer X((R)) kit provided a mean interface pressure of 46 mmHg and required a force in the range of 60-90 N to remove it. The Mediven((R)) ulcer kit exerted the same pressure but required force in the range of 150-190 N to remove it. Two kits (SurePress((R)) Comfort and VenoTrain((R)) Ulcertec) exerted a mean pressure of only 25 mmHg and needed a force in the range of 100-160 N to remove them. Nurses judged the Ulcer X and SurePress kits easiest to apply. Application of the VenoTrain kit was found slightly more difficult. The Mediven kit was judged to be difficult to use. CONCLUSIONS: Comparison of ease of application of compression-stocking kits in normal legs revealed marked differences between them. Only one system exerted a high pressure and was easy to apply. Direct comparison of these compression kits in leg-ulcer patients is required to assess whether our laboratory findings correlate with patient compliance and ulcer healing.

Lack of prophylaxis before the onset of acute venous thromboembolism among hospitalized cancer patients: the SWIss Venous ThromboEmbolism Registry (SWIVTER)

Venous thromboembolism (VTE) prophylaxis remains underutilized, particularly in cancer patients. We explored clinical predictors of prophylaxis in hospitalized cancer patients before the onset of acute VTE.

Comparison of low-strength compression stockings with bandages for the treatment of recalcitrant venous ulcers

OBJECTIVE: To compare the proportion and rate of healing, pain, and quality of life of low-strength medical compression stockings (MCS) with traditional bandages applied for the treatment of recalcitrant venous leg ulcers. METHODS: A single-center, randomized, open-label study was performed with consecutive patients. Sigvaris prototype MCS providing 15 mm Hg-25 mm Hg at the ankle were compared with multi-layer short-stretch bandages. In both groups, pads were placed above incompetent perforating veins in the ulcer area. The initial static pressure between the dressing-covered ulcer and the pad was 29 mm Hg and 49 mm Hg with MCS and bandages, respectively. Dynamic pressure measurements showed no difference. Compression was maintained day and night and changed every week. The primary endpoint was healing within 90 days. Secondary endpoints were healing within 180 days, time to healing, pain (weekly Likert scales), and monthly quality of life (ChronIc Venous Insufficiency Quality of Life [CIVIQ] questionnaire). RESULTS: Of 74 patients screened, 60 fulfilled the selection criteria and 55 completed the study; 28 in the MCS and 27 in the bandage group. Ulcers were recurrent (48%), long lasting (mean, 27 months), and large (mean, 13 cm2). All but one patient had deep venous reflux and/or incompetent perforating veins in addition to trunk varices. Characteristics of patients and ulcers were evenly distributed (exception: more edema in the MCS group; P = .019). Healing within 90 days was observed in 36% with MCS and in 48% with bandages (P = .350). Healing within 180 days was documented in 50% with MCS and in 67% with bandages (P = .210). Time to healing was identical. Pain scored 44 and 46 initially (on a scale in which 100 referred to maximum and 0 to no pain) and decreased within the first week to 20 and 28 in the MCS and bandage groups, respectively (P < .001 vs .010). Quality of life showed no difference between the treatment groups. In both groups, pain at 90 days had decreased by half, independent of completion of healing. Physical, social, and psychic impairment improved significantly in patients with healed ulcers only. CONCLUSION: Our study illustrates the difficulty of bringing large and long-standing venous ulcers to heal. The effect of compression with MCS was not different from that of compression with bandages. Both treatments alleviated pain promptly. Quality of life was improved only in patients whose ulcers had healed.

Adequacy of venous thromboprophylaxis in acutely ill medical patients (IMPART): multisite comparison of different clinical decision support systems

BACKGROUND: The adequacy of thromboprophylaxis prescriptions in acutely ill hospitalized medical patients needs improvement. OBJECTIVE: To prospectively assess the efficacy of thromboprophylaxis adequacy of various clinical decision support systems (CDSS) with the aim of increasing the use of explicit criteria for thromboprophylaxis prescription in nine Swiss medical services. METHODS: We randomly assigned medical services to a pocket digital assistant program (PDA), pocket cards (PC) and no CDSS (controls). In centers using an electronic chart, an e-alert system (eAlerts) was developed. After 4 months, we compared post-CDSS with baseline thromboprophylaxis adequacy for the various CDSS and control groups. RESULTS: Overall, 1085 patients were included (395 controls, 196 PC, 168 PDA, 326 eAlerts), 651 pre- and 434 post-CDSS implementation: 472 (43.5%) presented a risk of VTE justifying thromboprophylaxis (31.8% pre, 61.1% post) and 556 (51.2%) received thromboprophylaxis (54.2% pre, 46.8% post). The overall adequacy (% patients with adequate prescription) of pre- and post-CDSS implementation was 56.2 and 50.7 for controls (P = 0.29), 67.3 and 45.3 for PC (P = 0.002), 66.0 and 64.9 for PDA (P = 0.99), 50.5 and 56.2 for eAlerts (P = 0.37), respectively, eAlerts limited overprescription (56% pre, 31% post, P = 0.01). CONCLUSION: While pocket cards and handhelds did not improve thromboprophylaxis adequacy, eAlerts had a modest effect, particularly on the reduction of overprescription. This effect only partially contributes to the improvement of patient safety and more work is needed towards institution-tailored tools.

Impact of obesity on venous hemodynamics of the lower limbs

Obesity is a risk factor for chronic venous insufficiency and venous thromboembolism. The aim of this study was to compare venous flow parameters of the lower limbs assessed by duplex ultrasound scanning in obese and nonobese individuals according to body mass index (BMI).

Relationship between psychological distress and endogenous anticoagulants in patients with a previous venous thromboembolic event

Psychological distress, particularly anxiety and depression, has been associated with a prothrombotic state. However, the relationship between psychosocial factors and endogenous anticoagulants protein S (PS) and protein C (PC) has not previously been investigated. We explored the association between psychological distress, PS, and PC in patients with an objectively diagnosed venous thromboembolic event (VTE).

Posterior versus anterior circulation strokes: comparison of clinical, radiological and outcome characteristics

Physicians treating patients with posterior circulation strokes (PCS) tended to debate more on whether or not to introduce anticoagulation rather than performing investigations to identify stroke aetiology, as in patients with anterior circulation strokes (ACS). Recent findings suggest that stroke aetiologies of PCS and ACS are more alike than dissimilar, suggesting that PCS deserve the same investigations as ACS. The characteristics and current diagnostic evaluation between patients with PCS and ACS were compared.

Autotransfusion system or integrated automatic suction device in minimized extracorporeal circulation: influence on coagulation and inflammatory response

To measure surrogate markers of coagulation activation as well as of the systemic inflammatory response in patients undergoing primary elective coronary artery bypass grafting (CABG) using either the so-called Smart suction device or a continuous autotransfusion system (C.A.T.S.®).

[Spontaneous dural arterio-venous fistula at the cavernous sinus: detected by decompensation following endoscopic sinus surgery]

Spontaneous dural arterio-venous fistulas can imperceptibly develop over a long time period before they suddenly develop symptoms like bruit, loss of vision, exophthalmos and conjunctival injection. We present the rare case of an occult, para-infectious, dural arterio-venous fistula which became symptomatic after endoscopic sinus surgery. Conjunctival injection and slight exophthalmos developed due to decompensation of venous drainage probably by intraoperative positioning of the patient, positive pressure ventilation and nasal packing.

The human coronary collateral circulation

Coronary collaterals are an alternative source of blood supply to myocardium jeopardized by ischaemia. Well-developed coronary collateral arteries in patients with coronary artery disease (CAD) mitigate myocardial infarcts and improve survival.

Urinary proteomics before and after extracorporeal circulation in patients with and without acute kidney injury

Acute kidney injury is a well-known complication with high morbidity and mortality after cardiopulmonary bypass. Cardiopulmonary bypass-associated acute kidney injury is still poorly understood.

Long-term anticoagulation treatment for acute venous thromboembolism in patients with and without cancer. The SWIss Venous ThromboEmbolism Registry (SWIVTER) II

In patients with acute cancer-associated thrombosis, current consensus guidelines recommend anticoagulation therapy for an indefinite duration or until the cancer is resolved. Among 1,247 patients with acute venous thromboembolism (VTE) enrolled in the prospective Swiss Venous Thromboembolism Registry (SWIVTER) II from 18 hospitals, 315 (25%) had cancer of whom 179 (57%) had metastatic disease, 159 (50%) ongoing or recent chemotherapy, 83 (26%) prior cancer surgery, and 63 (20%) recurrent VTE. Long-term anticoagulation treatment for >12 months was more often planned in patients with versus without cancer (47% vs. 19%; p<0.001), with recurrent cancer-associated versus first cancer-associated VTE (70% vs. 41%; p<0.001), and with metastatic versus non-metastatic cancer (59% vs. 31%; p<0.001). In patients with cancer, recurrent VTE (OR 3.46; 95%CI 1.83-6.53), metastatic disease (OR 3.04; 95%CI 1.86-4.97), and the absence of an acute infection (OR 3.55; 95%CI 1.65-7.65) were independently associated with the intention to maintain anticoagulation for >12 months. In conclusion, long-term anticoagulation treatment for more than 12 months was planned in less than half of the cancer patients with acute VTE. The low rates of long-term anticoagulation in cancer patients with a first episode of VTE and in patients with non-metastatic cancer require particular attention.