Michael Harrison

Repeat general anaesthesia for paediatric dentistry

AIMS To investigate patterns of referral, disease and treatment for healthy children who had received two or more dental general anaesthetics (DGA) for exodontia. METHODS Records from 200 episodes of repeat DGA were studied retrospectively. RESULTS The mean age of patients at first referral was 5y4m, and the mean interval before repeat was 22 months. Self-referrals rose from 14% at DGA1 to 30% at DGA2. New caries at second referral, where all diagnosed disease had been treated at DGA1, accounted for only 15% of the total. Where a specific request was made in the referral, only 8% of letters matched the charting made in hospital. 30% of all specific requests were honoured, but then required treatment for previously diagnosed caries at DGA2.75% of single-tooth extractions required repeat DGA for caries left at DGA1. CONCLUSIONS It may be too optimistic to address only the most grossly diseased teeth when a child requires GA exodontia. A more radical treatment-planning approach, combining primary care, secondary care and public health considerations, may be required to avoid the unnecessary use of DGA.

Validation of the soft tissue restraints in a force-controlled knee simulator

Abstract In vitro testing of total knee replacements (TKRs) is important both at the design stage and after the production of the final components. It can predict long-term in vivo wear of TKRs. The two philosophies for knee testing are to drive the motion by displacement or to drive the motion by force. Both methods have advantages and disadvantages. For force control an accurate simulation of soft tissue restraints is required. This study was devised to assess the accuracy of the soft tissue restraints of the force-controlled Stanmore knee simulator in simulating the restraining forces of the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL). In order to do this, human cadaver knee joints were subjected to the ISO Standard Walking Cycle. The resulting kinematics were monitored when the soft tissue structures were intact, when the ACL and PCL were resected, and when they were simulated by springs positioned anteriorly and posteriorly. The stiffness of the springs was determined from the literature. Two different stiffnesses of springs were used which were 7.24 N/mm (designated as soft springs) and 33.8 N/mm (designated as hard springs). All the intact knees showed displacements that were within the range of the machine. Cutting the ACL and PCL resulted in anterior and posterior motion and internal external rotation that were significantly greater than the intact knee. Results showed that when the ACL and PCL were cut hard springs positioned anterior and posterior to the knee returned the knee to near normal anterior-posterior (AP) motion. Using hard springs in the posterior position in any condition reduced rotational displacements. Therefore using springs in a force-controlled simulator is a compromise. More accuracy may be obtained using springs that are of intermediate stiffness.

A systematic review of transcatheter aortic valve implantation via carotid artery access

BACKGROUND The carotid artery is a novel access route for transcatheter aortic valve implantation (TAVI). This may represent a viable alternative in patients unsuitable for TAVI via traditional transfemoral access, up to 20%, as well as other access routes such as subclavian, transapical and aortic. This systematic review summarises the current evidence for its safety and feasibility. METHODS A systematic review was conducted as per the Preferred Reporting Instructions for Systematic Reviews and Meta-analysis (PRISMA) guidelines using five electronic databases. RESULTS 16 studies were identified, including three prospective cohort studies, one retrospective cohort study, three case series and eight case reports. Data on 74 patients (mean age 76.9years) was extracted including pre-operative work-up, technical procedure details and outcomes. This found 1 intraoperative death, 2 further deaths within 30days, two incidences of transient ischaemic attack, no incidences of stroke, myocardial infarction, carotid access site complications or infection, 1 patient required new dialysis and 1 patient had an intraoperative dissection which resolved. Follow-up from 30days to 1year showed symptomatic improvement and echocardiographic improvement in line with those seen in transfemoral TAVI. CONCLUSIONS The available data on TAVI via carotid access demonstrate technical feasibility with comparable outcomes to other traditional access routes. A low number of patients, heterogeneous clinical endpoints and relatively short follow-up periods limit formal meta-analysis and firmer conclusions. For patients in which other access routes are impossible, TAVI via carotid access represents a viable and potentially crucial alternative in patients who might otherwise be untreatable.

Preventing the co-prescription of tamoxifen and fluoxetine in General Practice

Abstract In 2010 a population-based cohort study showed that there was decreased efficacy of the breast cancer drug tamoxifen when used in combination with fluoxetine, a commonly used SSRI antidepressant. The aim of this project was to identify patients who may be affected by this co-prescription and suggest a change in medication. The project was conducted across two GP practices in Clevedon (The Riverside Practice & The Green Practice), Bristol. The patients were all from the active patients register at each surgery. A search was conducted to find all those on tamoxifen and fluoxetine, using the EMIS computer system. These patients would then be sent a letter to attend clinic. The new data would then be discussed with them before recommending a change of antidepressant (typically to sertraline). Three patients were found to be on both medications. They were all called into clinic and changed from fluoxetine to sertraline. Furthermore a presentation was given to all GPs at the two surgeries alerting them to the new guidelines. A message was also set up to flash on the computer system whenever an attempt was made to co-prescribe the two drugs. All the patients on tamoxifen in these two practices are now receiving the optimum treatment. Furthermore interventions have been put in place to ensure that this remains the case in future. Another data collection should be conducted in one year. This project provides a good example of how this problem could be resolved at other GP surgeries.