Risk stratification by guidelines compared with risk assessment by risk equations applied to a MONICA sample

BACKGROUND: The World Health Organization/International Society of Hypertension (WHO/ISH) Hypertension Guidelines from 1999 propose a risk stratification scheme for estimating absolute risk for cardiovascular disease (CVD). Risk equations estimated by statistical methods are another way of predicting cardiovascular risk. OBJECTIVE: We studied the differences between these two approaches when applied to the same set of individuals with high blood pressure. DESIGN AND METHODS: The two northernmost counties in Sweden (NSW) constitute one of the centres in the WHO MONICA (monitoring trends and determinants in cardiovascular disease) Project. Three population surveys have been carried out in 1986, 1990 and 1994, and were used to estimate a risk equation for predicting the 10-year risk of fatal/non-fatal stroke and myocardial infarction. Another MONICA sample from 1999, a total of 5997 subjects, was classified according to the recent WHO/ISH risk stratification scheme. A risk assessment was also performed, by using the risk equations from the NSW MONICA sample and Framingham risk equations. RESULTS: The agreement between the two methods was good when the values obtained from the risk equation were averaged for each risk group obtained from the risk classification by guidelines. However, if the predicted risk for each individual was considered, the agreement was poor for the medium and high-risk groups. Although the average risk for all individuals is the same, many subjects have a higher risk or a lower risk than predicted by guidelines. CONCLUSIONS: Risk classification by the 1999 WHO/ISH Hypertension Guidelines is not accurate and detailed enough for medium- and high-risk patients, which could be of clinical importance in the medium risk group.     

A high blood level in the air trap reduces microemboli during hemodialysis

Previous studies have demonstrated the presence of air microemboli in the dialysis circuit and in the venous circulation of the patients during hemodialysis. In vitro studies indicate that a high blood level in the venous air trap reduces the extent of microbubble formation. The purpose of this study was to examine whether air microbubbles can be detected in the patient's access and if so, whether the degree of microbubble formation can be altered by changing the blood level in the venous air trap. This was a randomized, double‐blinded, interventional study of 20 chronic hemodialysis patients. The patients were assigned to hemodialysis with either an elevated or a low blood level in the air trap. The investigator and the patient were blinded to the settings. The numbers of microbubbles were measured at the site of the arteriovenous (AV) access for 2 min with the aid of an ultrasonic Doppler device. The blood level in the air trap was then altered to the opposite setting and a new measurement was carried out after an equilibration period of 30 min. Median (range) for the number of microbubbles measured with the high air trap level and the low air trap level in AV access was 2.5 (0–80) compared with 17.5 (0–77), respectively (P = 0.044). The degree of microbubble formation in hemodialysis patients with AV access was reduced significantly if the blood level in the air trap was kept high. The exposure of potentially harmful air microbubbles was thereby significantly reduced. This measure can be performed with no additional healthcare cost.     

Septic shock with multiorgan failure: from conventional apheresis to adsorption therapies

Septic shock is often associated with multiorgan failure, a life threatening clinical condition during which there is an imbalance in the proinflammatory and anti-inflammatory cytokines, chemokines, antigens, endotoxins, procoagulant, and anticoagulant factors and also resultant effects of therapeutic intervention like volume overload. Various extracorporeal therapies have shown some positive results as adjunctive therapeutic intervention to traditional antimicrobials in an effort to bring the inflammatory mediators to a homeostatic balance and to improve poor organ perfusion caused by hypotension and thrombosis in the microcirculation. This review focuses on current information on the use of therapeutic apheresis procedures as adjunctive therapy in such clinical situations as well as the exciting prospects for the near future. The sometimes disappointing results of early phase clinical studies may, in some cases, be related to the well known barriers to successful clinical trials in critically ill patients rather than to failure of the novel concept of adjunctive extracorporeal treatment of septic shock. It should be noted that some of the specialized apheresis technologies reviewed in this article are not yet available for clinical use in the United States as they are not yet approved for use by the US Food and Drug Administration.     

Plasma therapies in thrombotic syndromes

BACKGROUND: Plasma therapies are being applied to thombotic syndromes, but there are limited controlled studies. OBJECTIVE: To review the evidence and the current practices for plasma therapies in thrombotic syndromes. METHODS: Expert-enhanced evidence-based analysis. Evidence obtained as of Dec 31, 2002 using PubMed electronic reference library and expert-obtained library for a total of > 3,000 references obtained using the terms plasma therapy or plasma exchange or plasmapheresis or plasmafiltration or sorbents each combined with the words thrombotic syndrome or sepsis or septic shock. The authors screened the abstracts, reviewed the agreed set of papers, and compiled the recommendations. RESULTS: Plasma therapies, which alter the plasma components in patients, have been applied in thrombotic syndromes worldwide. In these patients, there is a biologic plausibility for plasma therapies since they have molecules that are prothrombotic and/or antifibrinolytic which would put them at risk for microvascular thrombosis and end-organ damage. There are respectively one randomized controlled trial (RCT) in primary thrombotic syndrome, and secondary thrombotic syndrome, which showed an improvement in mortality in applying plasma therapies (plasma exchange by centrifugation). However, there are numerous non-randomized and case series. Plasma exchange is accepted as the standard therapy for primary thrombotic syndrome as in thrombotic thrombocytopenic purpura (TTP). However, no consensus has been reached for plasma exchange in secondary thrombotic syndromes such as in sepsis, hemolytic uremic syndrome (HUS), thrombocytopenia associated multiple organ failure, TTP/HUS, s/p bone marrow or solid organ transplant, HELLP syndrome, immunologic disorders, drug exposure, or pancreatitis. CONCLUSIONS: As we understand more about the pathophysiology of thrombotic syndromes, specific plasma therapies can be applied for the specific need of a particular patient population. There are sufficient preliminary data to recommend a definitive RCT to evaluate the efficacy of the different types of plasma therapies in secondary thrombotic syndromes.     

Air bubbles pass the security system of the dialysis device without alarming

During hemodialysis microembolic findings have been noted after the venous chamber (subclavian vein). The aim of this study was to evaluate if air could pass the venous chamber and, if so, if it passes the safety-system detector for air-infusion without triggering an alarm.Various in vitro dialysis settings were performed using regular dialysis devices. A dextran fluid was used instead of blood to avoid the risk of development of emboli. Optical visualization as well as recirculation and collection of eventual air into an intermediate bag were investigated. In addition, a specifically designed ultrasound monitor was placed after the venous air trap to measure the presence of eventual microbubbles. Speed of dialysis fluid was changed, as was the level of the fluid in the air trap. Thereby a fluid level was considered "high" if it was close to the top of the air trap and "low" if it was around the mid part of the air trap. By optical vision microbubbles were seen at the bottom of the air trap and could pass the air trap towards the venous line without alarming. During recirculation several mL of air were collected in an intermediate bag after the venous line. Ultrasound monitoring exhibited the presence of microbubbles of the size of approximately 5 microm upwards passing to the venous line in all runs performed. Amount of bubbles differed between devices and in general an increased fluid speed correlated significantly with the increased counts of microbubbles/min. No alarming of the detector occurred. A more concentrated fluid allowed higher counts/min when flow was increased to 600 mL/min. Data revealed that air passes the safety-sensor in the air trap without alarming. The presence of air increased in general with fluid speed and a lower fluid level in the air trap. Differences were present between devices. If this affects the patients has to be elucidated.     

Development of air micro bubbles in the venous outlet line: an in vitro analysis of various air traps used for hemodialysis

Abstract:  Venous air traps were tested in vitro with respect to presence of micro bubbles. Three types of venous air traps were measured (Bioline, Bioline GmbH, Luckenwalde, Germany; Gambro, Gambro AB, Lund, Sweden; Fresenius M.C., Fresenius Medical Care AG & Co. KGaA, Bad Homburg, Germany). Measurements ( n  = 10) were taken for each air trap, fluid flow (50–600 mL/min), and fluid level (high/low). A 1.5-MHz ultrasound probe was used with an analysis device. The probe was mounted on the outlet line downstream of the venous air trap. A semisynthetic fluid was used to resemble blood viscosity. Occurrences of micro bubbles, without inducing an alarm of the dialysis device, were detected in almost all measurements. The amount of bubbles increased with increasing flow. There were more bubbles with low fluid level compared with high level. The Bioline tubing released the least bubbles in high fluid level. At low level, the Gambro tubing showed the least bubbles at flows 50–400 mL/min, and the Fresenius M.C. tubing showed the least bubbles at flows 400–600 mL/min. High fluid level in the air trap reduced generation of micro bubbles compared to low level, as did lower fluid flow versus high flow. The design of the air trap was also of importance.     

Hemodialysis dialyzers contribute to contamination of air microemboli that bypass the alarm system in the air trap

BACKGROUND: Previous studies have shown that micrometer-sized air bubbles are introduced into the patient during hemodialysis. The aim of this study was to investigate, in vitro, the influence of dialysis filters on the generation of air bubbles. METHODS: Three different kind of dialyzers were tested: one high-flux FX80 dry filter (Fresenius Medical Care AG&Co. KGaA, Bad Homburg, Germany), one low-flux F8HPS dry filter (Fresenius Medical Care AG&Co. KGaA, Bad Homburg, Germany) and a wet-stored APS-18u filter (Asahi Kasei Medical, Tokyo, Japan). The F8HPS was tested with pump flow ranging between 100 to 400 ml/min. The three filters were compared using a constant pump flow of 300 ml/min. Measurements were performed using an ultrasound Doppler instrument. RESULTS: In 90% of the series, bubbles were measured after the outlet line of the air trap without triggering an alarm. There were significantly more bubbles downstream than upstream of the filters F8HPS and FX80, while there was a significant reduction using the APS-18u. There was no reduction in the number of bubbles after passage through the air trap versus before the air trap (after the dialyzer). Increased priming volume reduced the extent of bubbles in the system. CONCLUSIONS: Data indicate that the air trap does not prevent air microemboli from entering the venous outlet part of the dialysis tubing (entry to the patient). More extended priming of the dialysis circuit may reduce the extent of microemboli that originate from dialysis filters. A wet filter may be favorable instead of dry-steam sterilized filters.     

Microbubbles of air may occur in the organs of hemodialysis patients

During hemodialysis (HD), blood that passes the dialysis device gets loaded with microbubbles (MB) of air that are returned to the patient without inducing an alarm. The aim with this study was to clarify if these signals are due to microembolies of air, clots, or artifacts, by histopathology of autopsy material of HD patients. These first results are from a patient on chronic HD. Due to pulmonary edema he was ultrafiltered. Within 30 minutes after the start, he suffered from a cardiac arrest and died. Autopsy verified the clinical findings. Microscopic investigation verified microembolies of air that were surrounded by fibrin in the lungs, brain, and heart. The study verified that MBs can enter the blood during HD and are trapped in the lungs. In addition, MBs pass the pulmonary capillaries and enter the arterial part of the body and are dispersed throughout the body. This can contribute to organ damage and be part of the poor prognoses seen in HD patients. Data support the importance to reduce MBs in the dialysis circuit.     

Analyses of data of patients with Thrombotic Microangiopathy in the WAA registry

Thrombotic Microangiopathy (TMA) is a histopathological feature of various diseases including thrombotic thrombocytopenic purpura and hemolytic uremic syndrome.The aim of this study was to investigate the outcome and prognostic variables of TMA-patients.

Materials and methods

Data were consecutively retrieved from the WAA-apheresis registry (www.waa-registry.org) during 2003–2009. Included were all 120 patients (1237 procedures) who suffered from various forms of TMA, as registered by the ICD-10 code M31.1. Besides registry data, more extensive information was retrieved from the latest 64 patients. Adverse events of the TMA patients were compared to those of the other patients in the registry.

Results

The mean age was 46 years (range 11–85 years, 57% women). In 72% therapeutic apheresis was due to an acute indication while a long-term indication was present in 28%. Plasma exchange was performed by centrifugation and filtration technique (95% and 4%, respectively), and immunoadsorption in 1% of the patients. Only fresh frozen plasma was used as replacement fluid in 69% of procedures. Adverse events were more frequent than in the general apheresis population (10% versus 5%, RR 1.9, CI 1.6–2.3). No death occurred due to apheresis treatment. Three percent of the procedures were interrupted. Bronchospasm and/or anaphylactic shock were present in two patients and one patient suffered from TRALI. At admission 26% were bedridden and needed to be fed. The risk of dying during the treatment period was significantly higher if the patient also suffered from a compromising disease, such as cancer. There was an inverse correlation between the ADAMTS13 level and the antibody titer (r = −0.47, p = 0.034).

Conclusions

Patients with TMA have an increased risk for moderate and severe AE compared to the general apheresis population. Many patients were severely ill at admission. The prognosis is worse if the patient also has a severe chronic disease. Even slightly increased ADAMTS13-antibody titers seem to have a negative impact on the ADAMTS13 levels.     

An international comparative study of blood pressure in populations of European vs. African descent

Background

The consistent finding of higher prevalence of hypertension in US blacks compared to whites has led to speculation that African-origin populations are particularly susceptible to this condition. Large surveys now provide new information on this issue.

Methods

Using a standardized analysis strategy we examined prevalence estimates for 8 white and 3 black populations (N = 85,000 participants).

Results

The range in hypertension prevalence was from 27 to 55% for whites and 14 to 44% for blacks.

Conclusions

These data demonstrate that not only is there a wide variation in hypertension prevalence among both racial groups, the rates among blacks are not unusually high when viewed internationally. These data suggest that the impact of environmental factors among both populations may have been under-appreciated.