Automated detection of enteric tubes misplaced in the respiratory tract on chest radiographs using deep learning with two centre validation.

AIM: To develop and test a model based on a convolutional neural network that can identify enteric tube position accurately on chest radiography. MATERIALS AND METHODS: The chest radiographs of adult patients were classified by radiologists based on enteric tube position as either critically misplaced (within the respiratory tract) or not critically misplaced (misplaced within the oesophagus or safely positioned below the diaphragm). A deep-learning model based on the 121-layer DenseNet architecture was developed using a training and validation set of 4,693 chest radiographs. The model was evaluated on an external test data set from a separate institution that consisted of 1,514 consecutive radiographs with a real-world incidence of critically misplaced enteric tubes. RESULTS: The receiver operator characteristic area under the curve was 0.90 and 0.92 for the internal validation and external test data sets, respectively. For the external data set with a prevalence of 4.4% of critically misplaced enteric tubes, the model achieved high accuracy (92%), sensitivity (80%), and specificity (92%) for identifying a critically misplaced enteric tube. The negative predictive value (99%) was higher than the positive predictive value (32%). CONCLUSION: The present study describes the development and external testing of a model that accurately identifies an enteric tube misplaced within the respiratory tract. This model could help reduce the risk of the catastrophic consequences of feeding through a misplaced enteric tube.

Putting machine learning into motion: applications in cardiovascular imaging.

Heart and circulatory diseases cause a quarter of all deaths in the UK and cardiac imaging offers an effective tool for early diagnosis and risk-stratification to improve premature death and disability. This domain of radiology is unique in that assessing flow and motion is essential for understanding and quantifying normal physiology and disease processes. Conventional image interpretation relies on manual analysis but this often fails to capture important prognostic features in the complex disturbances of cardiovascular physiology. Machine learning (ML) in cardiovascular imaging promises to be a transformative tool and addresses an unmet need for patient-specific management, accurate prediction of future events, and the discovery of tractable molecular mechanisms of disease. This review discusses the potential of ML across every aspect of image analysis including efficient acquisition, segmentation and motion tracking, disease classification, prediction tasks and modelling of genotype-phenotype interactions; however, significant challenges remain in access to high-quality data at scale, robust validation, and clinical interpretability.

Identifying the optimal regional predictor of right ventricular global function: a high-resolution three-dimensional cardiac magnetic resonance study.

Right ventricular (RV) function has prognostic value in acute, chronic and peri-operative disease, although the complex RV contractile pattern makes rapid assessment difficult. Several two-dimensional (2D) regional measures estimate RV function, however the optimal measure is not known. High-resolution three-dimensional (3D) cardiac magnetic resonance cine imaging was acquired in 300 healthy volunteers and a computational model of RV motion created. Points where regional function was significantly associated with global function were identified and a 2D, optimised single-point marker (SPM-O) of global function developed. This marker was prospectively compared with tricuspid annular plane systolic excursion (TAPSE), septum-freewall displacement (SFD) and their fractional change (TAPSE-F, SFD-F) in a test cohort of 300 patients in the prediction of RV ejection fraction. RV ejection fraction was significantly associated with systolic function in a contiguous 7.3 cm2 patch of the basal RV freewall combining transverse (38%), longitudinal (35%) and circumferential (27%) contraction and coinciding with the four-chamber view. In the test cohort, all single-point surrogates correlated with RV ejection fraction (p < 0.010), but correlation (R) was higher for SPM-O (R = 0.44, p < 0.001) than TAPSE (R = 0.24, p < 0.001) and SFD (R = 0.22, p < 0.001), and non-significantly higher than TAPSE-F (R = 0.40, p < 0.001) and SFD-F (R = 0.43, p < 0.001). SPM-O explained more of the observed variance in RV ejection fraction (19%) and predicted it more accurately than any other 2D marker (median error 2.8 ml vs 3.6 ml, p < 0.001). We conclude that systolic motion of the basal RV freewall predicts global function more accurately than other 2D estimators. However, no markers summarise 3D contractile patterns, limiting their predictive accuracy.

The impact of behavioural skills training on the knowledge, skills and well-being of front line staff in the intellectual disability sector: a clustered randomised control trial.

BACKGROUND: Staff with varying backgrounds and educational qualifications can be effectively trained to implement procedures in line with evidence-based practice. Behavioural skills training (BST) is a competency-based training model used to effectively educate a broad selection of professionals, including front line staff, in a range of work-related skills. However, BST has yet to be evaluated in a large group-based experiment. METHODS: This study involved a parallel cluster randomised control trial. Six service sites, with a total of 54 participants, were randomised to the intervention condition using the 'coin toss' method. The intervention condition used BST to coach intellectual disability staff in reinforcement, systematic prompting, functional communication training and task analysis. Six service sites, with a total of 50 participants, were also randomised to a control condition in which generalised training in behavioural interventions was restricted. Recruited service sites were randomly assigned to the intervention condition (N = 6, n = 54) or the control condition (N = 6, n = 50) at one point in time, immediately after recruitment and before baseline testing took place. Allocations were stratified by service type (residential or day) and geographical region. One member of the research team allocated service sites using the 'coin toss' method, and another member, blind to the allocations, decided which experimental arm would receive the intervention and which would be designated as control. It was not possible to mask the intervention from participants, but they were recruited prior to randomisation. RESULTS: Participants in the intervention condition demonstrated statistically significant improvements in their knowledge scores over the study period. Participants in the control condition showed no change or a statistically significant decrease in their knowledge scores. No statistically significant changes to well-being were observed for either group. There was clear evidence of knowledge maintenance, as well as skill acquisition and subsequent generalisation to the workplace environment, among participants in the intervention condition. Participants also evaluated the BST intervention positively. CONCLUSIONS: Results support BST as a method for disseminating evidence-based practice to front line staff working with adults with intellectual and developmental disabilities.

Acute myocardial infarction: susceptibility-weighted cardiac MRI for the detection of reperfusion haemorrhage at 1.5 T.

AIM: To assess whether susceptibility-weighted imaging (SWI) provides better image contrast for the detection of haemorrhagic ischaemia-reperfusion injury in the heart. MATERIALS AND METHODS: Thirty patients (all men; mean age 53 years) underwent cardiac magnetic resonance imaging (MRI) within 7 days of primary percutaneous intervention for acute ST elevation myocardial infarction (STEMI). Multiple gradient-echo T2* sequences with magnitude and phase reconstructions were acquired. A high-pass filtered phase map was used to create a mask for the SWI reconstructions. The difference in image contrast was assessed in those patients with microvascular obstruction. A mixed effects regression model was used to test the effect of echo time and reconstruction method on phase and contrast-to-noise ratio (CNR). Medians and interquartile ranges (IQR) are reported. RESULTS: T2* in haemorrhagic infarcts was shorter than in non-haemorrhagic infarcts (33.5 ms [24.9-43] versus 49.9 ms [44.6-67.6]; p=0.0007). The effect of echo time on phase was significant (p<0.0001), as was the effect of haemorrhage on phase (p=0.0016). SWI reconstruction had a significant effect on the CNR at all echo times (echoes 1-5, p<0.0001; echo 6, p=0.01; echo 7, p=0.02). The median echo number at which haemorrhage was first visible was less for SWI compared to source images (echo 2 versus echo 5, p=0.0002). CONCLUSION: Cardiac SWI improves the contrast between myocardial haemorrhage and the surrounding tissue following STEMI and has potential as a new tool for identifying patients with ischaemia-reperfusion injury.

The safe practice of CT coronary angiography in adult patients in UK imaging departments.

Computed tomography coronary angiography is increasingly used in imaging departments in the investigation of patients with chest pain and suspected coronary artery disease. Due to the routine use of heart rate controlling medication and the potential for very high radiation doses during these scans, there is a need for guidance on best practice for departments performing this examination, so the patient can be assured of a good quality scan and outcome in a safe environment. This article is a summary of the document on 'Standards of practice of computed tomography coronary angiography (CTCA) in adult patients' published by the Royal College of Radiologists (RCR) in December 2014.

Self-assembled quantum dots in a nanowire system for quantum photonics.

Quantum dots embedded within nanowires represent one of the most promising technologies for applications in quantum photonics. Whereas the top-down fabrication of such structures remains a technological challenge, their bottom-up fabrication through self-assembly is a potentially more powerful strategy. However, present approaches often yield quantum dots with large optical linewidths, making reproducibility of their physical properties difficult. We present a versatile quantum-dot-in-nanowire system that reproducibly self-assembles in core-shell GaAs/AlGaAs nanowires. The quantum dots form at the apex of a GaAs/AlGaAs interface, are highly stable, and can be positioned with nanometre precision relative to the nanowire centre. Unusually, their emission is blue-shifted relative to the lowest energy continuum states of the GaAs core. Large-scale electronic structure calculations show that the origin of the optical transitions lies in quantum confinement due to Al-rich barriers. By emitting in the red and self-assembling on silicon substrates, these quantum dots could therefore become building blocks for solid-state lighting devices and third-generation solar cells.

A numerical study of aortic flow stability and comparison with in vivo flow measurements.

The development of an engineering transitional turbulence model and its subsequent evaluation and validation for some diseased cardiovascular flows have been suggestive of its likely utility in normal aortas. The existence of experimental data from human aortas, acquired in the early 1970s with catheter-mounted hot film velocimeters, provided the opportunity to compare the performance of the model on such flows. A generic human aorta, derived from magnetic resonance anatomical and velocity images of a young volunteer, was used as the basis for varying both Reynolds number (Re) and Womersley parameter (α) to match four experimental data points from human ascending aortas, comprising two with disturbed flow and two with apparently undisturbed flow. Trials were made with three different levels of inflow turbulence intensity (Tu) to find if a single level could represent the four different cases with 4000 < Re < 10,000 and 17 < α < 26. A necessary boundary condition includes the inflow "turbulence" level, and convincing results were obtained for all four cases with inflow Tu = 1.0%, providing additional confidence in the application of the transitional model in flows in larger arteries. The Reynolds-averaged Navier-Stokes (RANS)-based shear stress transport (SST) transitional model is capable of capturing the correct flow state in the human aorta when low inflow turbulence intensity (1.0%) is specified.

Cellular mechanisms by which proinsulin C-peptide prevents insulin-induced neointima formation in human saphenous vein.

AIMS/HYPOTHESIS: Endothelial cells (ECs) and smooth muscle cells (SMCs) play key roles in the development of intimal hyperplasia in saphenous vein (SV) bypass grafts. In diabetic patients, insulin administration controls hyperglycaemia but cardiovascular complications remain. Insulin is synthesised as a pro-peptide, from which C-peptide is cleaved and released into the circulation with insulin; exogenous insulin lacks C-peptide. Here we investigate modulation of human SV neointima formation and SV-EC and SV-SMC function by insulin and C-peptide. METHODS: Effects of insulin and C-peptide on neointima formation (organ cultures), EC and SMC proliferation (cell counting), EC migration (scratch wound), SMC migration (Boyden chamber) and signalling (immunoblotting) were examined. A real-time RT-PCR array identified insulin-responsive genes, and results were confirmed by real-time RT-PCR. Targeted gene silencing (siRNA) was used to assess functional relevance. RESULTS: Insulin (100 nmol/l) augmented SV neointimal thickening (70% increase, 14 days), SMC proliferation (55% increase, 7 days) and migration (150% increase, 6 h); effects were abrogated by 10 nmol/l C-peptide. C-peptide did not affect insulin-induced Akt or extracellular signal-regulated kinase signalling (15 min), but array data and gene silencing implicated sterol regulatory element binding transcription factor 1 (SREBF1). Insulin (1-100 nmol/l) did not modify EC proliferation or migration, whereas 10 nmol/l C-peptide stimulated EC proliferation by 40% (5 days). CONCLUSIONS/INTERPRETATION: Our data support a causative role for insulin in human SV neointima formation with a novel counter-regulatory effect of proinsulin C-peptide. Thus, C-peptide can limit the detrimental effects of insulin on SMC function. Co-supplementing insulin therapy with C-peptide could improve therapy in insulin-treated patients.

White matter brain lesions in midlife familial hypercholesterolemic patients at 3-Tesla magnetic resonance imaging.

BACKGROUND: Patients with hypercholesterolemia of 60 years and older have an increased risk for white matter brain lesions and dementia. PURPOSE: To investigate whether patients with familial hypercholesterolemia (FH) develop white matter lesions at 3-Tesla (T) MRI as early as in midlife. MATERIAL AND METHODS: Non-diabetic, nonsmoking, and non-hypertensive heterozygous FH patients on treatment with maximally tolerated dose of a statin for more than 5 years (n = 14) and matched controls (n = 22) aged 25 to 60 years of age were studied. Imaging was performed at 3T with a fluid-attenuated T2-weighted MR pulse sequence and a T1-weighted spin-echo pulse sequence following 10 ml of i.v. gadopentetate dimeglumine. Images were evaluated by two independent readers. Fasting blood samples were taken. Student's t test was employed at P<0.05. RESULTS: Three volunteers and one FH patient had white matter lesions (P<0.53). No other evidence of past ischemic stroke was observed. Mean total serum cholesterol and low-density lipoprotein (LDL) cholesterol were significantly higher in the FH group (6.0+/-1.1 vs. 5.1+/-0.9 mmol/l, P<0.02 and 4.1+/-0.9 vs. 3.1+/-0.8 mmol/l, P<0.004, respectively). CONCLUSION: Heterozygous FH patients on statin treatment in the age range of 25 to 60 years are not at increased risk of white matter lesions at 3T MRI.

Attributes of excellent surgical trainers: An analysis of outstanding trainers.

Excellent surgical trainers play a key role in teaching, mentoring and inspiring the next generation of trainee surgeons. Although there are differences in approach, personality and technique among trainers, common themes exist for those that truly shine as examples of good training. The good surgical trainer has long been the "unsung hero" of patient safety, inspiring and imparting wisdom and skill in trainee surgeons, and instilling a sense of confidence and compassion. In order to recognise exceptional trainers, the Association of Surgeons in Training (ASiT) introduced the Silver Scalpel Award in 2000. The award acknowledges talented trainers who go the "extra mile" for their trainees, and the selection process includes both written nominations and structured interviews with the nominees. We wished to identify what makes the best trainers excellent, to see if these attributes could be used to develop recommendations on how to train and how to support trainers. Here we present an outline of key attributes of an excellent surgical trainer, based on qualitative synthesis of the interview sheets from Silver Scalpel interviews. These results clearly highlight that good trainers are first and foremost good doctors, and that good training goes hand-in-hand with excellent patient care. This symbiotic relationship between training and patient outcomes should be acknowledged, and trainers should be supported by their employers to empower them to carry out their dual roles of training and patient care to the best of their ability. Trainers are key role models to inspire the next generation of surgeons and exceptional trainers should be celebrated.

Computational study of aortic hemodynamics for patients with an abnormal aortic valve: The importance of secondary flow at the ascending aorta inlet.

Blood flow in the aorta is helical, but most computational studies ignore the presence of secondary flow components at the ascending aorta (AAo) inlet. The aim of this study is to ascertain the importance of inlet boundary conditions (BCs) in computational analysis of flow patterns in the thoracic aorta based on patient-specific images, with a particular focus on patients with an abnormal aortic valve. Two cases were studied: one presenting a severe aortic valve stenosis and the other with a mechanical valve. For both aorta models, three inlet BCs were compared; these included the flat profile and 1D through-plane velocity and 3D phase-contrast magnetic resonance imaging derived velocity profiles, with the latter being used for benchmarking. Our results showed that peak and mean velocities at the proximal end of the ascending aorta were underestimated by up to 41% when the secondary flow components were neglected. The results for helical flow descriptors highlighted the strong influence of secondary velocities on the helical flow structure in the AAo. Differences in all wall shear stress (WSS)-derived indices were much more pronounced in the AAo and aortic arch (AA) than in the descending aorta (DAo). Overall, this study demonstrates that using 3D velocity profiles as inlet BC is essential for patient-specific analysis of hemodynamics and WSS in the AAo and AA in the presence of an abnormal aortic valve. However, predicted flow in the DAo is less sensitive to the secondary velocities imposed at the inlet; hence, the 1D through-plane profile could be a sufficient inlet BC for studies focusing on distal regions of the thoracic aorta.

On the choice of outlet boundary conditions for patient-specific analysis of aortic flow using computational fluid dynamics.

Boundary conditions (BCs) are an essential part in computational fluid dynamics (CFD) simulations of blood flow in large arteries. Although several studies have investigated the influence of BCs on predicted flow patterns and hemodynamic wall parameters in various arterial models, there is a lack of comprehensive assessment of outlet BCs for patient-specific analysis of aortic flow. In this study, five different sets of outlet BCs were tested and compared using a subject-specific model of a normal aorta. Phase-contrast magnetic resonance imaging (PC-MRI) was performed on the same subject and velocity profiles extracted from the in vivo measurements were used as the inlet boundary condition. Computational results obtained with different outlet BCs were assessed in terms of their agreement with the PC-MRI velocity data and key hemodynamic parameters, such as pressure and flow waveforms and wall shear stress related indices. Our results showed that the best overall performance was achieved by using a well-tuned three-element Windkessel model at all model outlets, which not only gave a good agreement with in vivo flow data, but also produced physiological pressure waveforms and values. On the other hand, opening outlet BCs with zero pressure at multiple outlets failed to reproduce any physiologically relevant flow and pressure features.

A comparison of MR cholangiopancreatography at 1.5 and 3.0 Tesla.

Clinical MR systems operating at 3.0 Tesla have the potential to significantly improve spatial resolution due to the boost in intrinsic signal to noise ratio. However, body imaging at these field strengths presents a number of technical challenges. We performed a prospective pilot study in which 10 patients underwent an MR cholangiopancreatography (MRCP) examination consecutively on 1.5 and 3.0 Tesla systems (both Philips Intera). An axial half Fourier segmented turbo spin echo (HASTE) sequence and a coronal thick-slab 2D turbo-spin echo (TSE) sequence were compared on both systems. A reader measured the signal intensity (SI) ratios of common bile duct (CBD): liver, and CBD: fat on HASTE images and CBD: liver on the TSE images. A second reader performed a qualitative analysis of the intrahepatic and extrahepatic biliary anatomy. Quantitative data was compared using the paired t-test and qualitative data with the paired Wilcoxon signed rank test with p < 0.05. The quantitative analysis of the HASTE sequences showed a slightly higher signal intensity ratio (CBD:liver) at 3.0 Tesla compared with 1.5 Tesla (8.1 vs 5.6, p = 0.002). No significant difference was found between the SI ratios of (CBD:fat) on HASTE images or (CBD:liver) on TSE images. The qualitative analysis showed superior image quality of 3.0 Tesla over 1.5 Tesla images on both HASTE (31 vs 25, p = 0.032), and TSE sequences (34 vs 28, p = 0.043). This pilot study shows that MRCP is feasible at 3.0 Tesla with some improvement in image quality and signal characteristics. Further development may be achieved with sequence optimization and improved coil design.

A behavioural and neurochemical analysis of chronic and selective monoamine oxidase inhibition.

The effects of clorgyline were compared with the effects of (-)-deprenyl using measures of rewarding hypothalamic self-stimulation, regional monoamine metabolism and monoamine oxidase activity. Male Wistar rats trained to self-stimulate at half-maximal rates with unilateral bipolar lateral hypothalamic electrodes on a continuous reinforcement schedule were implanted subcutaneously with osmotic minipumps which delivered 1 mg X kg-1 drug per day or vehicle for 13 days. A response rate/stimulation frequency (reward summation) function was determined the day before minipump implantation and on days 5 and 13 of drug administration. Only clorgyline induced a shift to the left in the reward summation function at 5 and 13 days, indicating enhancement of reinforcement. Clonidine (50 micrograms X kg-1 IP) probe tests were run on days 2 and 10 to determine the sensitivity of alpha 2-noradrenaline receptors. Clorgyline induced an attenuation of the clonidine response on day 10 relative to day 2. The other groups exhibited no change in response to clonidine. Clorgyline also induced a progressive increase in self-stimulation rates; this effect was not observed with the other groups. The clorgyline effects were accompanied by an increase in regional brain levels of dopamine, noradrenaline and 5-hydroxytryptamine and a reduction of their acid metabolites. Clorgyline selectively inhibited type A monoamine oxidase, whereas (-)-deprenyl selectively inhibited type B monoamine oxidase.

Stentless aortic bioprosthesis? The way forward: early experience with the Edwards valve.

Tissue valve degeneration has been variably attributed to preservation and fixation methods. Additionally, a rigid valve ring might contribute to valve failure. The use of a nonstented porcine valve in the aortic position has clear hemodynamic advantages, and the lack of a stent may favorably influence long-term function. We have implanted stentless aortic valves (Prima valve) in 31 patients. There were 17 men. The mean age was 71.5 years (range, 50 to 83 years). After sculpturing of the sinuses the valve is positioned below the coronary arteries. Valve sizes ranged from 19 to 27 mm. There were no early or late deaths. Mean follow-up to date is 8.9 months (range, 4 weeks to 15 months). Early hemodynamic follow-up using Doppler echocardiography shows average peak systolic and mean gradients of 20.4 mm Hg and 8.6 mm Hg, respectively, at 4 weeks in 26 patients, with no significant change in 13 patients at 6 months. All patients are currently in New York Heart Association class I or II. Our early experience of stentless aortic valves shows them to be reliable with a satisfactory early hemodynamic profile. Their use in the elderly may conserve homografts for children and the young.

Topical aprotinin in cardiac operations.

We performed a prospective, randomized, double-blind trial of topical aprotinin versus placebo in 100 patients undergoing cardiac operations with cardiopulmonary bypass. Fifty-five patients received aprotinin. Forty underwent coronary artery bypass grafting (CABG) and 15 valve replacement +/- CABG. Of 45 patients in the control group 38 underwent CABG and 7 valve replacement +/- CABG. Aprotinin (50 mL; 70 mg) or placebo was applied topically to the heart, pericardium, and mediastinum before sternal closure. There were five reentries for bleeding with a surgical site identified in four. Mean blood loss was significantly less in the aprotinin group (653 versus 903 mL; p = 0.002), and fewer aprotinin patients received blood as a volume expander (67.5% versus 88%; p = 0.03). In coronary patients alone when aspirin administration was continued until the day of operation there was no difference between treatment and placebo groups (768 versus 879 mL). When aspirin administration was discontinued 2 weeks before operation there was a significant difference (558 versus 884 mL; p = 0.016) as in the group overall. This provides the potential for intrapericardial instillation for patients with excessive postoperative bleeding.

Aprotinin and bleeding in profoundly hypothermic perfusion.

Clinical observation led us to believe that aprotinin fails to preserve haemostatic function in patients undergoing deep hypothermic perfusion with or without circulatory arrest. A retrospective study was made of blood loss in 80 consecutive acute Type A dissection patients before and during the aprotinin era (1987-1992). After 1988 all patients were cooled below 20 degrees C pending circulatory arrest. Fourteen patients underwent aortic root replacement and 66 replacements of the ascending aorta. Age distribution (range 22-79 years) and type of operation were similar in the aprotinin and control groups. The impervious Hemashield (Meadox) graft was used for all but five patients. These underwent aortic root replacement with preclotted, valved conduits. Overall the mean blood loss for 27 patients operated without aprotinin was 837 ml per 24 h (standard error +/- 90) and for 53 patients with aprotinin 1,929 ml per 24 h (standard error +/- 90). There was a significant difference between the two groups when profoundly hypothermic perfusion was used, with greater bleeding in aprotinin-treated patients. There were six re-entries in the aprotinin group and none in the control patients. There were ten hospital deaths (11.1%). A greater incidence of bleeding and thrombosis-related deaths was recorded for the aprotinin-treated patients. In addition, four surviving aprotinin patients suffered severe coagulation defect with blood loss greater than 4,500 ml and platelets less than 50 x 10(6). We suggest that aprotinin inhibits the protease enzymes which maintain the fluid state of blood during hypothermic low flow and arrest states. Disseminated intravascular coagulation may consume platelets thereby predisposing to abnormal bleeding and potentially fatal thrombotic events. The use of aprotinin in profoundly hypothermic perfusion should be adopted cautiously.

Does modern cardiac surgery require conventional intensive care?

We considered that, with modern perfusion equipment and mildly hypothermic cardiopulmonary bypass, protracted post-operative ventilation in an intensive care unit (ITU) is no longer required after most cardiac operations. We used a three-bedded cardiac recovery area (CRA) within the operating suite for 1,000 patients between January 1990 and June 1991. Forty-five patients with special needs were managed in the ITU. The time to extubation (T50%; range) for coronary bypass, aortic valve, mitral valve, and double-valve patients was 2.0 (0-42), 2.5 (0-12), 3.0 (0-15), and 3.0 (1-36) hours, respectively. Recovery beds were re-used allowing 5-6 operations daily. The difference in nursing staff complement for a CRA versus ITU bed was 4.5/7.8. Patient management was by nurse specialists supported by cardiac surgeons. Intervention by cardiac anaesthetists or intensivists was limited to specific ventilatory problems or renal failure. The early extubation policy failed in ten patients (five coronary, three aortic, one mitral and one double-valve patient) through poor pre-operative respiratory function, left ventricular failure or intra-operative events. The overall mortality in CRA was 1.4%. The mean duration of post-operative stay was 7 days (range 5-12). We conclude that a CRA staffed by nurse practitioners provides a safe and effective alternative to the anaesthetist-managed ITU. A rapid turnover of CRA beds removes the constraints of ITU bed availability.

Assessment of human long saphenous vein function with minimally invasive harvesting with the Mayo stripper.

BACKGROUND: The use of the Mayo Stripper to harvest the long saphenous vein has been shown to improve morbidity from leg wound incisions. It has not been universally accepted because of a perceived increase in injury to the venous conduit. OBJECTIVE: To compare the function of undistended autologous long saphenous vein harvested by a Mayo stripper with the traditional 'open' technique in the same patient (n = 12) appearance. METHODS: Vascular reactivity was assessed in isolated organ baths. Contractile function was measured in response to increasing concentrations (10(-9)-10(-5) mol) of 5-hydroxytryptamine and noradrenaline. This was calculated as a percentage of the maximum contractile response to 90 mM KCl measured in millinewtons (mN) (control 41.4 +/- 12.1, (n = 11), open technique 35.8 +/- 11.1, (n = 11), Mayo stripper 33.7 +/- 15.9, (n = 11)). The endothelial dependent and independent function was assessed with acetylcholine and sodium nitroprusside, respectively. RESULTS: There was no significant difference in response to both constrictors and dilators between vein taken with the Mayo stripper compared with the traditional open technique (n = 6 for each observation; P > 0.05 by ANOVA). Histological examination by light microscopy of the vessel segments removed with the Mayo stripper was unable to show any significant damage to the vessel wall. Both functional and morphological studies were conducted by 'blinded' observers. One-year follow-up with magnetic resonance angiography (MRA) and stress thallium tomography demonstrated a patency rate with lower and upper estimates of 80 and 94%. CONCLUSIONS: We have shown that harvesting the long saphenous vein with a Mayo stripper does not compromise vascular reactivity of the long saphenous vein or long-term patency.