Achieving good-quality consent: review of literature, case law and guidance.

BACKGROUND: Informed consent is an integral part of clinical practice. There is widespread agreement amongst health professionals that obtaining procedural consent needs to move away from a unidirectional transfer of information to a process of supporting patients in making informed, self-determined decisions. This review aimed to identify processes and measures that warrant consideration when engaging in consent-based discussions with competent patients undergoing elective procedures. METHODS: Formal written guidance from the General Medical Council and Royal College of Surgeons of England, in addition to peer-reviewed literature and case law, was considered in the formulation of this review. RESULTS: A framework for obtaining consent is presented that is informed by the key tenets of shared decision-making (SDM), a model that advocates the contribution of both the clinician and patient to the decision-making process through emphasis on patient participation, analysis of empirical evidence, and effective information exchange. Moreover, areas of contention are highlighted in which further guidance and research are necessary for improved enhancement of the consent process. CONCLUSION: This SDM-centric framework provides structure, detail and suggestions for achieving meaningful consent.

ANTECEDENTES: El consentimiento informado es una parte integral de la práctica clínica. Existe un acuerdo generalizado entre los profesionales de la salud en que lograr el consentimiento del procedimiento no debe ser una transferencia unidireccional de información, sino un proceso de apoyo a los pacientes en la toma de decisiones informadas y autodeterminadas. Esta revisión tiene como objetivo identificar procesos y medidas que deban ser considerados al hablar sobre el consentimiento con pacientes autosuficientes sometidos a procedimientos quirúrgicos electivos. MÉTODOS: Al planear esta revisión se tuvo en cuenta la recomendación formal por escrito del Consejo Médico General y del Royal College of Surgeons of England, además de la literatura revisada por pares y de la jurisprudencia. RESULTADOS: Se presenta un marco para lograr el consentimiento que se basa en los principios clave de la toma de decisiones compartida (Shared Decision-Making, SDM); un modelo que aboga por la contribución, tanto del médico como del paciente, al proceso de toma de decisiones a través del énfasis en la participación del paciente, el análisis de la evidencia empírica y el intercambio efectivo de información. Además, se destacan áreas de contención en las que se necesitan más recomendaciones y más investigación para mejorar aún más el proceso del consentimiento. CONCLUSIÓN: Este marco centrado en la SDM proporciona estructura, detalles y sugerencias sobre cómo se puede lograr un consentimiento informado satisfactorio.

Variation in duplex peak systolic velocity measurement in a multi-site vascular service.

OBJECTIVE: Duplex US (DUS) is increasingly utilised as a first-line investigation for the assessment of carotid disease. For clinical decision-making, DUS assessment must be accurate and reproducible to ensure reliability. We aimed to investigate the variability in peak systolic velocity (PSV) measurement in a multi-site vascular network. METHODS: DUS measurements of PSV were taken from continuous and pulsatile flow, generated by a high fidelity phantom, by 12 experienced vascular scientists across four hospitals. Participants were blinded to the actual PSV value (50 cm/s). RESULTS: We observed an average error of 13.2% (± 8.3) and 11.6% (± 7.5) in PSV measurements taken from pulsatile and continuous waveforms, respectively. Measurements of PSV using the pulsatile waveform demonstrated statistically significant variation across all hospitals; ((hospital/mean) A 43.9 cm/s, B 61.7 cm/s, C 57.4 cm/s, D 47.7 cm/s, p=0.001). Further analysis demonstrated statistically significant variation in 4 instrumentation-related factors when measuring from a pulsatile waveform (Doppler angle, angle of insonation, velocity range, scale range). CONCLUSION: We observed a significant level of error and variation in PSV measurements across four sites within our vascular network. Variation in instrumentation-related factors may be accountable for this. In light of the centralisation of vascular services, it is increasingly important to unify and implement scanning protocols in order to reduce error and inter-site variability.

Validation of a novel duplex ultrasound objective structured assessment of technical skills (DUOSATS) for arterial stenosis detection.

INTRODUCTION: Duplex ultrasound facilitates bedside diagnosis and hence timely patient care. Its uptake has been hampered by training and accreditation issues. We have developed an assessment tool for Duplex arterial stenosis measurement for both simulator and patient based training. METHODS: A novel assessment tool: duplex ultrasound assessment of technical skills was developed. A modified duplex ultrasound assessment of technical skills was used for simulator training. Novice, intermediate experience and expert users of duplex ultrasound were invited to participate. Participants viewed an instructional video and were allowed ample time to familiarize with the equipment. Participants' attempts were recorded and independently assessed by four experts using the modified duplex ultrasound assessment of technical skills. 'Global' assessment was also done on a four point Likert scale. Content, construct and concurrent validity as well as reliability were evaluated. RESULTS: Content and construct validity as well as reliability were demonstrated. The simulator had good satisfaction rating from participants: median 4; range 3-5. Receiver operator characteristic analysis has established a cut point of 22/ 34 and 25/ 40 were most appropriate for simulator and patient based assessment respectively. We have validated a novel assessment tool for duplex arterial stenosis detection. Further work is underway to establish transference validity of simulator training to improved skill in scanning patients. CONCLUSIONS: We have developed and validated duplex ultrasound assessment of technical skills for simulator training.

The role of simulation in developing surgical skills.

Surgical training has followed the master-apprentice model for centuries but is currently undergoing a paradigm shift. The traditional model is inefficient with no guarantee of case mix, quality, or quantity. There is a growing focus on competency-based medical education in response to restrictions on doctors' working hours and the traditional mantra of "see one, do one, teach one" is being increasingly questioned. The medical profession is subject to more scrutiny than ever before and is facing mounting financial, clinical, and political pressures. Simulation may be a means of addressing these challenges. It provides a way for trainees to practice technical tasks in a protected environment without putting patients at risk and helps to shorten the learning curve. The evidence for simulation-based training in orthopedic surgery using synthetic models, cadavers, and virtual reality simulators is constantly developing, though further work is needed to ensure the transfer of skills to the operating theatre.

The surgical management of 73 vascular malformations and preoperative predictive factors of major haemorrhage--a single centre experience.

OBJECTIVES: In our series of patients with congenital vascular malformations (CVMs) we investigate the preoperative factors for predicting major haemorrhage at surgery and propose an algorithm for their surgical management. DESIGN: This is a partly prospective case series of patients with severe symptoms/complications due to CVMs. MATERIALS AND METHODS: Data were collected on 73 consecutive procedures in 41 patients with CVMs from 1992 to 2006 at a large university hospital and the association of following factors with blood loss during the procedure were investigated: type of procedure, possibility of proximal tourniquet use, lesion flow characteristics, previous history of major haemorrhage with CVM surgery, platelet counts and length of hospital stay. RESULTS: Significantly higher blood loss was associated with debulking surgery (p=0.006) and with previous history of major haemorrhage during CVM surgery, (p=0.041). Blood loss was higher in lesions where proximal tourniquet application was not possible (p=0.093). High-flow lesions were not strongly associated with major blood loss (p=0.288). Major blood loss (>2l) occurred in 16 (20.8%) procedures performed on 11 (26.2%) patients, but this did not prolong hospital stay. CONCLUSION: Surgery can potentially improve morbidity/mortality in patients with life/limb-threatening complications or severe symptoms due to CVMs, providing they are managed in multidisciplinary specialised centres.

Peripheral arterial revascularization causing parallel increased activity of pro- and anti-inflammatory mediators.

AIM: The aim of this study was to investigate the interaction between the proinflammatory mediator interleukin (IL)-6 and anti-inflammatory mediator IL-10 in ischemia reperfusion injury following peripheral arterial revascularization. METHODS: Three groups of patients were recruited (group 1: femoral angiography alone [n=14]; group 2: radiologically successful ilio/femoral angioplasty [n=10]; and group 3: peripheral surgical bypass [n=11]). Peripheral venous blood obtained for all patients at pre-procedure and at 1 h and 24 h post-procedure. After centrifugation supernatant plasma was separated and analysed for proinflammatory cytokine IL-6 and anti-inflammatory cytokine IL-10 using enzyme linked immunosorbent assay (ELISA) technique. RESULTS: Levels of IL-6 at 1 and 24 h were significantly higher in group 3 (P<0.05 and P<0.01, respectively) and at 24 h in group 2 as compared to group 1 (P<0.05). Levels of IL-10 were significantly higher in group 3 at 24 h (P<0.05). In group 2 levels of IL-10 higher than group 1, but this did not reach statistical significance (P=0.07). CONCLUSIONS: Raised levels of IL-6 at 1 and 24 h in patients undergoing operative peripheral bypass suggest early and persistent proinflammatory activity, similarly patients with successful angioplasty also demonstrated similar persistent proinflammatory activity of IL-6 at 24 h. Raised levels of IL-10 at 24 h represents anti-inflammatory properties of IL-10 counter acting inflammatory response.

Nerve tissue protein S-100 and neurone-specific enolase concentrations in cerebrospinal fluid and blood during carotid endarterectomy.

Nerve tissue protein S-100 and neurone-specific enolase levels in serum were studied in 10 patients before, during and for 2 days after elective carotid endarterectomy performed under general anaesthesia and using a Javid Shunt. In six patients, simultaneous cerebrospinal fluid samples were also obtained. Serum nerve tissue protein S-100 was normal throughout the operation, but in one patient with severe hypertension, levels increased to 1.38 microg. l-1 at 1 h postoperatively. Two patients showed an increase in cerebrospinal fluid nerve tissue protein S-100 during clamping: these patients also had neurological deficits at 6 months. Serum neurone-specific enolase increased from 5.8 to 9.3 microg.l-1 during shunting while cerebrospinal fluid neurone-specific enolase did not change. Uncomplicated carotid endarterectomy does not produce cerebral damage as measured by serum nerve tissue protein S-100; cerebrospinal fluid nerve tissue protein S-100 may be more sensitive for minor cerebral damage. Neurone-specific enolase appeared to be nonspecific. The lack of correlation between the neuroproteins may need to be explained before relying on these simple assays as diagnostic indicators of cerebral ischaemia.

Arterial flow induces changes in saphenous vein endothelium proteins transduced by cation channels.

OBJECTIVES: expression of leukocyte adhesins and proteins controlling thrombosis is likely to be an important determinant of graft patency early following vein bypass. We have previously demonstrated rapid increase in endothelial ICAM-1 and nitric oxide synthase (eNOS) concentrations in human saphenous vein exposed to arterial flow. The aim of this study was to investigate whether ion-channel-blocking drugs could alter these flow-induced changes. METHODS: human saphenous vein segments, freshly excised from patients, were placed in a validated in vitro circuit using flow conditions shown to simulate arterial or venous circulations for 90 min, in the presence or absence of ion-channel blockers. The concentrations of ICAM-1, VCAM-1, eNOS and tissue factor (TF) were assessed by quantitative immunohistochemistry in vein exposed to flow and compared with that in freshly excised vein from the same patient. The endothelial protein concentration was calculated as the mean area of staining as percentage of that for the control protein CD31, using computer-aided image analysis. RESULTS: after arterial flow conditions the area ratio of ICAM-1 increased from 21.4+/-1.4 to 44.6+/-2.0%, of eNOS increased from 50.0+/-5.6 to 70.1+/-5.0%, of VCAM-1 decreased from 16.6+/-3.4 to 3.6+/-1.0%, whereas TF staining area ratio was unchanged. Inclusion of the non-selective K(+)channel blocker, tetraethylammonium, in the arterial perfusion solution abolished all these arterial flow-induced changes. Inclusion of the K(+)ATP channel blocker, glibenclamide, selectively abolished the arterial flow-induced changes in ICAM-1 and VCAM-1. Inclusion of the calcium channel blocker, nifedipine, abolished the arterial flow-induced changes in eNOS and VCAM-1 but increased the TF staining area ratio from 3.0+/-0.4 to 8.5+/-0.7%, p=0.01. Inclusion of the stretch-activated cation-channel blocker, gadolinium, enhanced the arterial flow-induced increase in eNOS, but prevented the arterial flow-induced increase in ICAM-1. CONCLUSIONS: perfusion of veins under arterial flow conditions with gadolinium was associated with low endothelial concentrations of ICAM-1, VCAM-1 and TF, but high levels of eNOS. Such a concentration of endothelial proteins may be advantageous in newly implanted vein grafts. In contrast, nifedipine could have adverse effects by promoting increase in TF concentration.

Functional renal perfusion imaging with colour mapping: is it a useful adjunct to spiral CT of in the assessment of abdominal aortic aneurysm (AAA)?

AIM: To ensure optimal timing with pre-operative spiral CT for abdominal aortic aneurysms (AAA), an initial 'timing' single level CT is commonly performed with a small bolus of contrast. This can be exploited to obtain adjunct functional information on renal perfusion. We have investigated the potential of this to measure renal perfusion, to produce colour renal perfusion maps and to predict surgical outcome in infrarenal aortic aneurysm assessment. METHODS: We studied 21 patients being assessed for repair of infrarenal AAA. Prior to the spiral CT, a single level through the renal hili and aorta was scanned after the intravenous injection of 25 ml of contrast given at 10 ml/s. Ten 1 s duration scans were performed from 8 to 30 s after injection. Optimal timing for CT angiography can then be determined. Time-density curves were then drawn for both kidneys and aorta using regions of interest (ROIs) or pixel-by-pixel analysis. Renal cortical perfusion was measured using both ROI analysis and pseudocolour perfusion images. Following previous work, perfusion was calculated as the peak upslope of the tissue time density curve divided by peak aortic enhancement. RESULTS: Cortical mean perfusion averaged 2.48 ml/min per ml (range 0.8-3.7 ml/min per ml n = 34) and the values obtained agreed with literature expectations. Follow up in the 10 patients proceeding to AAA repair suggest low mean perfusion values and predict a raised postoperative creatinine (P < 0.05) CONCLUSIONS: Additional functional data and imaging can be obtained from the initial timing scan of a CT study, without requiring a dedicated study.

Intra-operative antithrombotic therapy with low molecular weight heparin in aortic surgery. How should heparin be administered?

This prospective study evaluates, for the first time, the efficacy of heparinisation with low molecular weight heparin (LMWH) in aortic surgery and identifies the most effective route of administration for heparin. Sixteen patients undergoing abdominal aortic grafting for aneurysmal and occlusive disease were studied. They were randomised to receive 10,000 anti Xa units of LMWH either intravenously or directly into the aorta before or after aortic cross-clamping. Serial venous blood samples and a paired arterial sample from the superficial femoral artery were taken for the estimation of systemic and lower limb heparin activity. All three methods of administration gave therapeutic levels of heparin in the systemic and lower limb circulation. Intravenous and aortic administration before clamping resulted in significantly higher systemic levels when compared with aortic injection after clamping (p less than 0.05 Mann-Whitney U test). Intra-aortic administration resulted in a significantly higher heparin activity in the lower limb when compared with the intravenous route (p less than 0.05). No patient developed distal thrombosis. This study demonstrates that the most effective way of giving heparin in aortic surgery is by direct injection into the aorta. Administration of LMWH after cross-clamping results in less systemic activity which may help to reduce any haemorrhagic side effects.

Benign non-traumatic inflammatory strictures of the extrahepatic biliary system.

Obstructive jaundice was the presenting feature in 12 patients with benign, non-traumatic strictures of the extrahepatic bile ducts. Ages at presentation ranged from 1.5 to 60 years and 11 were initially referred with diagnoses of malignant strictures. Histological examination, however, showed benign changes of chronic inflammation, with ulceration in seven, which were distinct from those of primary sclerosing cholangitis. All of the patients remain well from 3 to 14 years after surgery. The aetiology of the strictures is not known.

Acute urinary retention: which catheter?

There is no scientific data on which is the best method and catheter to use in acute urinary retention in males. We therefore compared the efficiency of a size 12 G latex rubber balloon catheter with a similar calibre but more expensive catheter made of polyvinyl-chloride (PVC). A total of 50 patients was studied and a 100% successful catheterisation rate was recorded at first attempt with both catheters, with no significant complications. The importance of the correct management of acute urinary retention, especially adequate analgesia, is stressed and it is concluded that either catheter is satisfactory.

Metabolic consequences of forced diuresis following prostatectomy.

The efficacy and metabolic consequences of a standardised forced diuresis regime following prostatectomy were studied in three parts. A retrospective review of 372 patients. A detailed prospective study of blood and urine electrolyte changes in 25 patients. A prospective study of urinary oxalate levels in 15 patients. The regime was effective in safely preventing post-operative clot retention. In 54% of patients the plasma sodium fell below 135 mmol/l. Hypokalaemia was mild and transient except in patients on long-term diuretics. There was a significant per-operative fall in serum calcium levels. It was concluded that forced diuresis is a safe and effective method of reducing clot retention following prostatectomy. The high incidence of post-operative hyponatraemia suggests that absorption of glycine solution at transurethral prostatectomy is a common occurrence.

Prostaglandins and acute pancreatitis--experimental and clinical studies.

Acute pancreatitis has a mortality of 10-20 per cent, and in cases of acute haemorrhagic pancreatitis this rises to 80-90 per cent. At present there is no reliable treatment for this condition. Based on the hypothesis that the release locally and systemically of the intracellularly activated pancreatic digestive enzymes is due to cell membrane instability, we have studied the cytoprotective (cell membrane stabilizing) role of prostaglandins in this condition. In the first part of this study, an animal model of acute pancreatitis with a mortality of 100 per cent by 14 days has been established by feeding mice a choline-deficient ethionine supplemented diet. Using this model we have demonstrated improved survival (16 out of 50 survived 14 days or longer) by administering prostaglandin E2 subcutaneously (P less than 0 X 02). We have demonstrated that the improved survival is dose-dependent, in the range 2 X 5-5 X 0 mg/kg body weight 8 hourly (P less than 0 X 02) and time-dependent, still being effective if treatment is delayed for 24 h (P less than 0 X 02). Great emphasis has been placed on not commencing treatment until after the induction of acute pancreatitis. In the second part we have used cell membrane marker enzymes to study the cell membrane stabilizing effect of prostaglandin E2 in the human. It has been demonstrated that cell membrane instability occurs. In 12 of 50 episodes treated by prostaglandin E2 infusion, the lysosomal, mitochondrial and cell membranes are stabilized, thus decreasing the release of intracellular enzymes.