Subclavian stents and stent-grafts: cause for concern?

PURPOSE: To report cases of stent and stent-graft fracture in the subclavian vessels. METHODS AND RESULTS: Three patients with self-expanding stents of 3 different types in 1 subclavian artery and 2 subclavian veins presented with recurrent symptoms 6 months to 2 years after stenting. All devices showed signs of compression with stent fracture. The covered stent in the subclavian artery was excised. Of the 2 venous patients, 1 was treated with first rib resection and the other refused further treatment. CONCLUSIONS: The subclavian vessels are prone to flexion during movement, and the vessels may be compressed by external structures, including the clavicle and first rib. Stents that have not been designed to withstand these forces may be damaged.     

Insulin analogues and cancer risk: cause for concern or cause célèbre?

People with diabetes, particularly those with type 2 diabetes, may be at an increased risk of cancer. Furthermore, their cancer risk may be modified by treatment choices. In this respect, metformin may be protective, whereas insulin and insulin analogues can function as growth factors and therefore have theoretical potential to promote tumour proliferation. Analogues causing inappropriate prolonged stimulation of the insulin receptor, or excess stimulation of the IGF‐1 receptor, are the most likely to show mitogenic properties in laboratory studies. Some recent epidemiological studies appear to be consistent with these experimental findings, suggesting that there could be different relative risks for cancer associated with different insulins, although these studies have attracted some methodological criticism. However, it is biologically plausible that hormonal factors that influence neoplasia could begin to manifest their effects in surprisingly short timescales (within 2 years) and hence these epidemiological studies justify further research. Even if future research were to document an increase in cancer risk among insulin users, this would be unlikely to significantly diminish the favourable benefit‐risk ratio for patients requiring insulin therapy. There is a need for further population studies and for the development of new laboratory models that are more sophisticated than previous experimental methods employed to assess potential tumour growth‐promoting properties of insulins.     

Current uses of transfusion administration sets: a cause for concern?

There is potential for inappropriate use of transfusion administration sets when used in combination with modern infusion pumps with consequences for patient safety. The aims of our study were to (i) establish if the design and testing of transfusion sets specified in International Standard ISO 1135‐4 are adequate for their current applications, (ii) identify if infusion pumps currently supplied in the UK for blood component administration are suitable for this purpose and (iii) determine the additional control measures needed to be applied by manufacturers and users to ensure patient safety. Keyword literature search was carried out to review and correlate important transfusion parameters with resultant adverse effects. Units for occlusion pressure, flow rate and haemolysis were standardised for ease of comparison. A sample of transfusion set instructions for use was reviewed. Principal suppliers of infusion pumps to the UK market were surveyed to identify those sold for blood transfusion, their recommended operating parameters and compatible transfusion sets. Previous work showed clinically unacceptable haemolysis at pressures above 40 kPa. Modern infusion pumps operate under negative pressures of up to 210 kPa. ISO 1135‐4 design and test requirements do not match this performance and in particular omit testing under negative pressure. Transfusion sets surveyed did not indicate flow or pressure restrictions or specify the blood components with which they had been validated. ISO 1135‐4 requires updating and has been initiated. Meanwhile, recommendations are made for transfusion set manufacturers concerning pressure limitations and restrictions on blood component type and for users concerning purchase, configuration and validation of infusion pumps and disposables.     

Tranexamic acid in cardiac surgery: is there a cause for concern?

The withdrawal of marketing approval for aprotinin resulted in more clinicians administering tranexamic acid to patients at increased risk of bleeding and adverse outcome. The latest in a series of retrospective analyses of observational data is published in Critical Care and suggests an increase in mortality, when compared to data from the aprotinin era, in those patients having surgery when a cardiac chamber is opened. The added observation of an increase in cerebral excitatory phenomena (seizure activity) with tranexamic acid has a known mechanism and questions if such patients should be given this drug.     

The increasing use of silver-based products as antimicrobial agents: a useful development or a cause for concern?

Silver first gained regulatory approval for use as an antimicrobial agent in the early 20th century, but its usage diminished with the introduction of antibiotics in the 1940s. Recently, however, topical silver has gained popularity once again, principally in the management of open wounds. This has been largely due to the spread of methicillin-resistant Staphylococcus aureus and the resultant reduction in first-line antibiotic prescribing. The increase in the use of topical silver has raised issues concerning silver resistance, together with questions about the standardization of antimicrobial testing methods for silver. Issues related to silver product testing include a failure to establish standard procedures for determining MIC values, an absence of recognized breakpoints, a lack of conformity in the way different products release silver and variations in the effects of microbiological media on silver release and the measurement of inhibitory activity. The clinical incidence of silver resistance remains low, and emergence of resistance can be minimized if the level of silver ions released from products is high and the bactericidal activity rapid.     

Hyperventilation: cause or effect?

A young person presenting with shortness of breath is common to the accident and emergency department. Usually this hyperventilation is anxiety related or a panic attack, but sometimes it can be caused by a serious underlying condition like pulmonary embolus. Acute shortness of breath in any patient should never be dismissed lightly. It is important to realise that pulmonary embolus can present without chest pain and with shortness of breath as the major symptom. Such patients can be distinguished by close attention to history and examination, risk factors for thromboembolic disease and the use of basic investigations (electrocardiogram, chest radiography and arterial blood gas analysis). A serious cause for shortness of breath must be excluded before labelling it as "hysteria" or "panic".     

A cause for concern? Osteopoikilosis found incidentally in the emergency department: a case report

Osteopoikilosis is a rare, inherited bone disorder, which is usually found incidentally on x ray. It may be mistaken for other, more serious disorders such as bony metastases, causing undue distress to the doctor and patient.