Significant Radiation Dose Reduction in the Hybrid Operating Room Using a Novel X-ray Imaging Technology.

OBJECTIVE/BACKGROUND: To prospectively quantify radiation dose change in aortoiliac endovascular procedures in the hybrid operating room (OR) for patients and medical staff with a novel X-ray imaging technology (ClarityIQ technology), and to assess whether procedure or fluoroscopy time or dose of iodinated contrast was affected. METHODS: A prospective study including 138 patients was performed to compare radiation dose before and after installation of a novel X-ray imaging technology. Endovascular aneurysm repair (EVAR) was performed in 37 patients and an endovascular procedure for aortoiliac occlusive disease (AIOD) in 101. Patient radiation dose in air kerma (AK) and dose area product (DAP), patient demographics, and procedural data were recorded. Staff radiation dose was measured with real time personal dosimetry measurements. In both the EVAR and AIOD groups the reference system, ALX (AlluraXper FD20; Philips Healthcare, Best, the Netherlands), was compared with the upgraded X-ray system, CIQ (AlluraClarity FD20; Philips Healthcare). Procedure time, fluoroscopy time, and iodinated contrast dose were recorded. RESULTS: Patient radiation dose reduction in the EVAR group, in median AK, was 56% (ALX = 1,262.5 mGy; CIQ = 556.0 mGy [p < .01]); and in median DAP it was 57% (ALX = 224.4 Gycm(2) and CIQ = 95.8 Gycm(2) [p < .01]). Patient radiation dose reduction in the AIOD group, in median AK, was 76% (ALX = 1,011.0 mGy; CIQ = 248.0 mGy [p < .01]); and in median DAP it was 73% (ALX = 138.1 Gycm(2); CIQ = 38.0 Gycm(2) [p < .01]). Staff dose reduction in the EVAR group was 16% (ALX = 70.1 µSv; CIQ = 59.2 µSv [p = .43]) and in the AIOD group it was 69% (ALX = 96.2 µSv; CIQ = 30.1 µSv [p < .01]). There was no statistically significant difference between patient demographics, procedure time, fluoroscopy time, and iodinated contrast medium use in the two treatment groups before and after installation. CONCLUSION: A novel X-ray imaging technology in the hybrid OR suite resulted in a significant reduction of patient and staff radiation dose without affecting procedure length, fluoroscopy time, or use of contrast.

Splenic size after division of the short gastric vessels in Nissen fundoplication in children.

PURPOSE: Nissen fundoplication is an effective treatment for gastro-esophageal reflux disease (GERD). Mobilization of the gastric fundus during fundoplication requires division of short gastric vessels of the spleen, which may cause splenic ischemia. The aim of this study was to determine if Nissen fundoplication results in hypotrophy of the spleen. METHODS: We performed pre-operative and post-operative ultrasound measurements of the spleen in children undergoing Nissen fundoplication. During operation, the surgeon estimated the compromised blood flow by assessment of the percentage of discoloration of the spleen. RESULTS: Twenty-four consecutive children were analyzed. Discoloration of the upper pole of the spleen was observed in 11 patients (48%) of a median estimated splenic surface of 20% (range 5-50%). The median ratio for pre-operative and post-operative length, width, and area of the spleen was 0.97, 1.03, and 0.96, respectively. The percentage of the estimated perfusion defect during surgery was not correlated with the ratios. In three patients, the area ratio was smaller than 0.8 (0.67-0.75), meaning that the area decreased with at least 20% after surgery. In none of these patients a discoloration was observed. CONCLUSION: Discoloration of the spleen after Nissen fundoplication is not associated with post-operative splenic atrophy.

Does laparoscopy lower the threshold for the surgical treatment of gastroesophageal reflux disease in children?

OBJECTIVE: To assess whether laparoscopic surgery lowers the threshold for surgical intervention, we examined whether the introduction of the laparoscopic technique at our institution in 1997 has resulted in an increase in antireflux surgery in children at our clinic. PATIENTS AND METHODS: The number of annual fundoplications between 1997 and 2008 at a single institution was assessed in children younger than 18 years. The number of fundoplications was compared with the number of pyloromyotomies and appendicectomies per year in the same period of time to prove or exclude a general increase in the referral of children. RESULTS: Since 1997, the proportion of laparoscopic fundoplications increased from 60% in 1997 to 100% in 2008. During this period, 109 laparoscopic fundoplications were performed: 31 in the period from 1997 to 2002 and 78 from 2003 to 2008. Regression analysis shows a significant increase in the number of performed fundoplications (slope: 1.03 ± 0.28, P = 0.0043), whereas both the number of pyloromyotomies and appendicectomies remained stable (slopes: -0.14 ± 0.40, P = 0.73, and -0.75 ± 0.47, P = 0.14, respectively). CONCLUSIONS: Since the introduction of minimally invasive surgery at our tertiary referral center in 1997, the number of patients referred for an antireflux operation has increased. This cannot be explained by an increase of referrals from outside the region or a change in the indication for surgery. We conclude that laparoscopy lowers the threshold for the surgical treatment of gastroesophageal reflux disease in children.

[Differences between men and women in the composition of atherosclerotic plaque, as an explanation for the lower success rate of carotid endarterectomy in women]. / Verschillen in samenstelling van de atherosclerotische plaque tussen mannen en vrouwen als verklaring voor het geringere succes van carotisendarteriëctomie bij vrouwen.

OBJECTIVE: To determine whether men and women differ in the histological characteristics of plaque material removed at carotid endarterectomy. DESIGN: Observational and descriptive. METHODS: Carotid endarterectomy plaque specimens obtained from 45 degrees consecutive patients (135 women, 315 men) were assessed for the presence of macrophages, smooth muscle cells, collagen, calcifications, and luminal thrombus by means ofimmunohistochemical staining. The plaques were categorised in 3 phenotypes according to the overall presentation of histological characteristics and the lipid level. Protein was isolated from the plaques to determine the interleukin-6 (IL-6) and IL-8 concentrations and the activity of matrix metalloproteinase-8 (MMP-8) and MMP-9. RESULTS: Atheromatous plaques (> 40% fat) were less frequently observed in women than in men (22 versus 40%; p < 0.001). In addition, more women than men had a low macrophage staining (18 versus 11%; p = 0.05) and strong smooth muscle cell staining (38 versus 24%; p = 0.001). Compared with men, women had a lower plaque concentration of IL-8 and lower MMP-8 activity. The observed differences were most pronounced in the asymptomatic group. An atheromatous plaque occurred in 9% of asymptomatic women compared to 39% ofasymptomatic men (p = 0.02). Moreover, a large proportion of plaques obtained from asymptomatic women showed high smooth muscle cell content (53 versus 30%; p = 0.03) and high collagen content (55 versus 24%; p = 0.003). All relations between gender and plaque characteristics, except for MMP-8, remained the same in a multivariate analysis that was adjusted for clinical presentation and other cardiovascular risk factors. CONCLUSION: Women with a carotid stenosis had more stable plaques than men, independent of clinical presentation and cardiovascular risk profile. Asymptomatic women demonstrated the highest prevalence of stable plaques. These findings may explain why women benefit less from carotid endarterectomy than men.

[Purpura fulminans: a rare complication of chickenpox]. / Purpura fulminans, een zeldzame complicatie van waterpokken.

A 3.5-year-old boy presented with purpura on the buttocks extending towards both legs. Two weeks earlier, he had had chickenpox. Because of the rapidly progressing purpura with clinical signs of hypovolaemic shock, he was treated with fresh frozen plasma, packed red blood cells, intravenous immunoglobulins, prednisolone, acyclovir and ceftriaxone. The purpura stopped spreading. In the next few days, the skin at the site of the purpura became necrotic and was excised, as was the subcutis and part of the fascia on both legs and flanks. The right lower leg was amputated and a temporary colostomy was created to prevent faecal contamination of the wounds. The patient recovered and was discharged after three months. Purpura fulminans is a rare complication after a primary infection with varicella zoster virus. A varicella infection may lead to protein S deficiency resulting in diffuse intravascular coagulation and severe skin defects.

The versatility of progress testing assessed in an international context: a start for benchmarking global standardization?

Sharing and collaboration relating to progress testing already takes place on a national level and allows for quality control and comparisons of the participating institutions. This study explores the possibilities of international sharing of the progress test after correction for cultural bias and translation problems. Three progress tests were reviewed and administered to 3043 Pretoria and 3001 Maastricht medical students. In total, 16% of the items were potentially biased and removed from the test items administered to the Pretoria students (9% due to translation problems; 7% due to cultural differences). Of the three clusters (basic, clinical and social sciences) the social sciences contained most bias (32%), basic sciences least (11%). The differences that were found, comparing the student results of both schools, seem a reflection of the deliberate accentuations that both curricula pursue. The results suggest that the progress test methodology provides a versatile instrument that can be used to assess medical schools across the world. Sharing of test material is a viable strategy and test outcomes are interesting and can be used in international quality control.

Carotid atherosclerotic plaque characteristics are associated with microembolization during carotid endarterectomy and procedural outcome.

BACKGROUND AND PURPOSE: During carotid endarterectomy (CEA), microemboli may occur, resulting in perioperative adverse cerebral events. The objective of the present study was to investigate the relation between atherosclerotic plaque characteristics and the occurrence of microemboli or adverse events during CEA. METHODS: Patients (n=200, 205 procedures) eligible for CEA were monitored by perioperative transcranial Doppler. The following phases were discriminated during CEA: dissection, shunting, release of the clamp, and wound closure. Each carotid plaque was stained for collagen, macrophages, smooth muscle cells, hematoxylin, and elastin. Semiquantitative analyses were performed on all stainings. Plaques were categorized into 3 groups based on overall appearance (fibrous, fibroatheromatous, or atheromatous). RESULTS: Fibrous plaques were associated with the occurrence of more microemboli during clamp release and wound closure compared with atheromatous plaques (P=0.04 and P=0.02, respectively). Transient ischemic attacks and minor stroke occurred in 5 of 205 (2.4%) and 6 of 205 (2.9%) patients, respectively. Adverse cerebral outcome was significantly related to the number of microembolic events during dissection (P=0.003) but not during shunting, clamp release, or wound closure. More cerebrovascular adverse events occurred in patients with atheromatous plaques (7/69) compared with patients with fibrous or fibroatheromatous plaques (4/138) (P=0.04). CONCLUSIONS: Intraoperatively, a higher number of microemboli were associated with the presence of a fibrous but not an atheromatous plaque. However, atheromatous plaques were more prevalent in patients with subsequent immediate adverse events. In addition, specifically the number of microemboli detected during the dissection phase were related to immediate adverse events.

Panel expertise for an Angoff standard setting procedure in progress testing: item writers compared to recently graduated students.

INTRODUCTION: An earlier study showed that an Angoff procedure with > or = 10 recently graduated students as judges can be used to estimate the passing score of a progress test. As the acceptability and feasibility of this approach are questionable, we conducted an Angoff procedure with test item writers as judges. This paper reports on the reliability and credibility of this procedure and compares the standards set by the two different panels. METHODS: Fourteen item writers judged 146 test items. Recently graduated students had assessed these items in a previous study. Generalizability was investigated as a function of the number of items and judges. Credibility was judged by comparing the pass/fail rates associated with the Angoff standard, a relative standard and a fixed standard. The Angoff standards obtained by item writers and graduates were compared. RESULTS: The variance associated with consistent variability of item writers across items was 1.5% and for graduate students it was 0.4%. An acceptable error score required 39 judges. Item-Angoff estimates of the two panels and item P-values correlated highly. Failure rates of 57%, 55% and 7% were associated with the item writers' standard, the fixed standard and the graduates' standard, respectively. CONCLUSION: The graduates' and the item writers' standards differed substantially, as did the associated failure rates. A panel of 39 item writers is not feasible. The item writers' passing score appears to be less credible. The credibility of the graduates' standard needs further evaluation. The acceptability and feasibility of a panel consisting of both students and item writers may be worth investigating.

Growth of medical knowledge.

BACKGROUND: Knowledge is an essential component of medical competence and a major objective of medical education. Thus, the degree of acquisition of knowledge by students is one of the measures of the effectiveness of a medical curriculum. We studied the growth in student knowledge over the course of Maastricht Medical School's 6-year problem-based curriculum. METHODS: We analysed 60 491 progress test (PT) scores of 3226 undergraduate students at Maastricht Medical School. During the 6-year curriculum a student sits 24 PTs (i.e. four PTs in each year), intended to assess knowledge at graduation level. On each test occasion all students are given the same PT, which means that in year 1 a student is expected to score considerably lower than in year 6. The PT is therefore a longitudinal, objective assessment instrument. Mean scores for overall knowledge and for clinical, basic, and behavioural/social sciences knowledge were calculated and used to estimate growth curves. FINDINGS: Overall medical knowledge and clinical sciences knowledge demonstrated a steady upward growth curve. However, the curves for behavioural/social sciences and basic sciences started to level off in years 4 and 5, respectively. The increase in knowledge was greatest for clinical sciences (43%), whereas it was 32% and 25% for basic and behavioural/social sciences, respectively. INTERPRETATION: Maastricht Medical School claims to offer a problem-based, student-centred, horizontally and vertically integrated curriculum in the first 4 years, followed by clerkships in years 5 and 6. Students learn by analysing patient problems and exploring pathophysiological explanations. Originally, it was intended that students' knowledge of behavioural/social sciences would continue to increase during their clerkships. However, the results for years 5 and 6 show diminishing growth in basic and behavioural/social sciences knowledge compared to overall and clinical sciences knowledge, which appears to suggest there are discrepancies between the actual and the planned curricula. Further research is needed to explain this.

The effect on reliability of adding a separate written assessment component to an objective structured clinical examination.

PURPOSE: To determine the effect on test reliability when a separate written assessment component is added to an objective structured clinical examination (OSCE). METHOD: Volunteers (n=38) from Maastricht Medical School were recruited to take a skills-related knowledge test in addition to their regular end-of-year OSCE. The OSCE scores of these volunteers did not differ from those of the other students of their class. Multivariate generalizability theory was used to investigate the combined reliability of the two test formats as well as their respective contributions to overall reliability. RESULTS: Combining the two formats has an added value. The loss of reliability due to the use of fewer stations in the OSCE can be fully compensated by lengthening the written test component. CONCLUSION: From the perspective of test reliability, it is possible to economize on the resources needed for performance-based assessment by adding a separate written test component.

An antibiotic policy to prevent emergence of resistant bacilli.

BACKGROUND: Fear of infection in neonatal intensive care units (NICUs) often leads to early use of empiric broad-spectrum antibiotics, a strategy that selects for resistant bacteria. We investigated whether the emergence of resistant strains could be halted by modifying the empiric antibiotic regimens to remove the selective pressure that favours resistant bacteria. METHODS: Two identical NICUs were assigned to different empiric antibiotic regimens. On unit A, penicillin G and tobramycin were used for early-onset septicaemia, flucloxacillin and tobramycin were used for late-onset septicaemia, and no broad-spectrum beta-lactam antibiotics, such as amoxicillin and cefotaxime were used. In unit B, intravenous amoxicillin with cefotaxime was the empiric therapy. After 6 months of the study the units exchanged regimens. Rectal and respiratory cultures were taken on a weekly basis. FINDINGS: There were 436 admissions, divided equally between the two regimens (218 in each). Three neonates treated with the penicillin-tobramycin regimen became colonised with bacilli resistant to the empirical therapy used versus 41 neonates on the amoxicillin-cefotaxime regimen (p<.0001). The relative risk for colonisation with strains resistant to the empirical therapy per 1000 patient days at risk was 18 times higher for the amoxicillin-cefotaxime regimen compared with the penicillin-tobramycin regimen (95% CI 5.6-58.0). Enterobacter cloacae was the predominant bacillus in neonates on the amoxicillin-cefotaxime regimen, whereas Escherichia coli predominated in neonates on the penicillin-tobramycin regimen. These colonisation patterns were also seen when the units exchanged regimens. INTERPRETATION: Policies regarding the empiric use of antibiotics do matter in the control of antimicrobial resistance. A regimen avoiding amoxicillin and cefotaxime restricts the resistance problem.

Reliability and credibility of an angoff standard setting procedure in progress testing using recent graduates as judges.

INTRODUCTION: Progress testing is an assessment method that samples the complete domain of knowledge that is considered pertinent to undergraduate medical education. Because of the comprehensive nature of this test, it is very difficult to set a passing score. We obtained a progress test standard using an Angoff procedure with recent graduates as judges. This paper reports on the reliability and credibility of this approach. METHODS: The Angoff procedure was applied to a sample of 146 progress test items. The items were judged by a panel of eight recently graduated students. Generalizability theory was used to investigate the reliability as a function of the number of items and judges. Credibility was judged by comparing the pass/fail rates resulting from the standard arrived at by the Angoff procedure with those obtained using a relative and a fixed standard. RESULTS: The results indicate that an acceptable error score can be achieved, yielding a precision within one percentage on the scoring scale, by using 10 judges on a full-length progress test (i.e. 250 items). The pass/fail rates associated with the Angoff standard came closest to those of the relative standard, which takes variations in test difficulty into account. A high correlation was found between item-Angoff estimates and the item P-values. CONCLUSION: The results of this study suggest that the Angoff procedure, using recently graduated students as judges, is an appropriate standard setting method for a progress test.

An Inter- and Intra-University Comparison With Short Case-Based Testing.

Comparisons between PBL and non-PBL medical schools on problem-solving ability often show no differences. This could be either due to the fact that no difference in problem-solving skills exists or that the instruments used are inadequate. In this study a key-feature approach case-based examination was used to compare two medical schools in the Netherlands, one of which has a PBL curriculum (Maastricht) and one which has a program half way a transition from a non-PBL towards a PBL curriculum (Groningen). Differences were found both in proficiency scores and in the pattern of response times, both supporting the assumption that a PBL approach would lead to a higher level of problem solving ability. The effect size, however, is not as large as originally assumed by the PBL proponents. Conclusions must be drawn with caution, but it seems likely that a test based on large numbers of short cases is the most sensitive in detecting differences in problem solving ability between students of different curricula.

Microanalytical screening of all major stratum corneum lipids by sequential high-performance thin-layer chromatography.

For rapid and sensitive screening of lipid biochemical abnormalities of scaling skin disorders a sequential, one-dimensional high-performance thin-layer chromatographic method (HPTLC) has been developed. All major human stratum corneum lipid classes, i.e., cholesterol sulfate, glucosylceramides, six major ceramide fractions, free sterols, free fatty acids, triglycerides, sterol esters, squalene, and n-alkanes, are separated and quantitated after a stepwise development of a single silica gel 60 HPTLC-plate using three consecutive solvent systems. Reproducible results have been obtained by degradative charring as well as fluorescence detection. By fluorescence detection the method is particularly suitable for the determination of minor amounts of cholesterol sulfate and other sterols.