Realistic computer modelling of stent retriever thrombectomy: a hybrid finite-element analysis-smoothed particle hydrodynamics model.

Stent retriever thrombectomy is a pre-eminent treatment modality for large vessel ischaemic stroke. Simulation of thrombectomy could help understand stent and clot mechanics in failed cases and provide a digital testbed for the development of new, safer devices. Here, we present a novel, in silico thrombectomy method using a hybrid finite-element analysis (FEA) and smoothed particle hydrodynamics (SPH). Inspired by its biological structure and components, the blood clot was modelled with the hybrid FEA-SPH method. The Solitaire self-expanding stent was parametrically reconstructed from micro-CT imaging and was modelled as three-dimensional finite beam elements. Our simulation encompassed all steps of mechanical thrombectomy, including stent packaging, delivery and self-expansion into the clot, and clot extraction. To test the feasibility of our method, we simulated clot extraction in simple straight vessels. This was compared against in vitro thrombectomies using the same stent, vessel geometry, and clot size and composition. Comparisons with benchtop tests indicated that our model was able to accurately simulate clot deflection and penetration of stent wires into the clot, the relative movement of the clot and stent during extraction, and clot fragmentation/embolus formation. In this study, we demonstrated that coupling FEA and SPH techniques could realistically model stent retriever thrombectomy.

Intensive Care Unit nosocomial sinusitis at the Rasoul Akram Hospital: Tehran, Iran, 2007-2008.

BACKGROUND: Nosocomial rhino sinusitis causes major problems in all Intensive Care Units (ICUs). OBJECTIVE: To describe incidence, epidemiologic, clinical manifestations, and microbiologic findings in ICUs admitted cases with nosocomial sinusitis. METHODS#ENTITYSTARTX00026; MATERIALS: A prospective, cross sectional study done in Pediatric & Adult ICUs in Rasoul Akram Hospital; Tehran Iran (2007-2008). Para-nasal sinus computed tomography (CT) was performed in all adults with fever of unknown origin (FUO) within 48h of admission and repeated thereafter (4-7 days). Infectious sinusitis was diagnosed by microbiological analysis of sinus fluid aspirates. RESULTS: Acute bacterial nosocomial sinusitis proved in 82% (51/ 63) of all cases. Head trauma was the most common cause; (n = 22, 45%) of cases. The results of culture were positive for 45 cases (82%). Of 45 culture positives, 19 yielded Gram negative organisms (41%) and 9 (22%) gave Gram positives (S. aureous, Streptococus spp). The remainders (n = 17, 37%) consisted of mixed aerobic/anaerobic bacteria. Seven cases, were positive in gram staining of sinus drainage and these were positive in culture for S. pneumonia (n = 5), Hemophilus influenza (n = 2). The type of organisms were not related to Glasgow Coma Scale in cases (P = 0.3). CONCLUSION: Nosocomial organisms isolated were quite different from community acquired rhino sinusitis cases. Investigation of CT scan and drainage of Para-nasal sinuses would be helpful in undiagnosed FUO cases, especially in traumatic patients. Optimal treatment usually consists of removal of the tubes, mobilizing the patient, and administration the broad-spectrum antibiotics.

Comparison of the outcome of burn patients using acute-phase plasma base deficit.

Background. In recent years, plasma base deficit has been used as a marker to determine the status of tissue perfusion in trauma patients and also to predict the outcome of these patients. This study was performed to investigate the effect of plasma base deficit in predicting burn patient outcome. Methods. This prospective cohort study was performed from October 2009 to October 2010 in the acute phase of burn patients who were admitted within 6 h post-injury to Motahari Burn Hospital in Iran. The patients were divided into two groups based on the plasma base deficit in the first 24 h post-injury: group A, in which the mean plasma base deficit was less than or equal to -6 (more negative), and group B, in which the mean plasma base deficit greater than -6. Statistical analysis was performed using SPSS v.16 software. Results. Thirty-eight patients were enrolled in each group. The mean plasma base deficit in group A (-7.76 ± 2.18 mmol) was significantly less than that in group B (-1.19 ± 2.82) mmol (p < 0.05). Although there was no significant difference between the mean of fluid resuscitation and urine output in the first 24 h after injury between the two groups (p > 0.05) and despite removal of interfering factors, there were significant differences between the systemic inflammatory response syndrome and the multiple organ dysfunction syndrome score and the percentage of sepsis between the two groups (p < 0.05). The mortality rate in group A (63.2%) was significantly higher than that in group B (36.8%) (p > 0.05). Conclusion. The plasma base deficit can be used as a valuable marker in the resuscitation of burn patients, along with clinical criteria. Physiological indicators (burn percentage, age, and mucosal burns) are not sufficient to predict mortality and morbidity in burn patients, and it is necessary to investigate the role of biochemical markers such as base deficit in determining the final outcome of burn patients.

Evaluation of an interferon-gamma release assay in young contacts of active tuberculosis cases.

In a cross-sectional study in a hospital in Tehran in 2006-08 the QuantiFERON-TB interferon-gamma release assay (QTB) was compared with the tuberculin skin test (TST) in 59 young people (aged < 20 years) with close contact with immunocompetent cases of proven pulmonary tuberculosis. After 1 year follow-up 10 subjects had progressed to tuberculosis disease and received treatment; TSTwas positive in 30% and QTB in 100%. Of the 49 non-progressive subjects, TST was positive in 10.4% and QTB in 16.3%. The agreement between TST and QTB assay in non-progressive subjects was poor (K = 0.43). False positive and false negative rates for TST were 40.0% and 9.3% respectively; positive and predictive values were 60.0% and 90.7%. We suggest adding the interferon assay to the skin test in the decision to perform chest X-ray or to start chemoprophylaxis at least in younger subjects (aged < 20 years).

Evaluation of an interferon-gamma release assay in young contacts of active tuberculosis cases

In a cross-sectional study in a hospital in Tehran in 2006-08 the QuantiFERON[Registered]-TB interferon-gamma release assay [QTB] was compared with the tuberculin skin test [TST] in 59 young people [aged<20 years] with close contact with immunocompetent cases of proven pulmonary tuberculosis. After 1 year follow-up 10 subjects had progressed to tuberculosis disease and received treatment; TST was positive in 30% and QTB in 100%. Of the 49 non-progressive subjects, TST was positive in 10.4% and QTB in 16.3%. The agreement between TST and QTB assay in non-progressive subjects was poor [Kappa=0.43]. False positive and false negative rates for TST were 40.0% and 9.3% respectively; positive and predictive values were 60.0% and 90.7%. We suggest adding the interferon assay to the skin test in the decision to perform chest X-ray or to start chemoprophylaxis at least in younger subjects [aged<20 years]

Socio-economic and medical determinants of low birth weight in Iran: 20 years after establishment of a primary healthcare network.

OBJECTIVE: Establishment of a primary healthcare network in Iran has provided free and universal access to primary health care. Although the health status of Iranians has improved since this network was established, the low-birthweight rate has not decreased. The objective of the present study was to describe socio-economic and medical factors related to low birth weight in the context of free and universal access to primary health care. DESIGN: Descriptive, hospital-based prospective study. METHODS: Data about socio-economic, reproductive and prenatal condition of 4510 live singleton births from June to October 2004 were gathered using a standard questionnaire by interview and record review. The effect of these conditions on birth weight was investigated using a logistic regression model. RESULTS: Of 4510 newborns, 305 (6.8%) were low birth weight. Among these low-birthweight newborns, there were 159 preterm and 146 term newborns. Mothers with a primary and secondary education [odds ratio (OR) 6.83, 95% confidence interval (CI) 2.35-7.34 and OR 4.81, 95%CI 1.95-6.37, respectively], who lived with farmer and unskilled worker husbands (OR 2.52, 95%CI 1.12-4.66 and OR 2.91, 95%CI 1.35-2.52, respectively), with a birth interval of 1 year or less (OR 3.54, 95%CI 1.80-5.95) and height less than 155cm (OR 1.82, 95%CI 1.12-3.31) were more likely to have low-birthweight infants. CONCLUSION: In the context of free and universal access to health care, it is recommended that policy makers should place more emphasis on education as it imparts knowledge and thus influences dietary habits and birth-spacing behaviour. This will lead to a better nutritional status, particularly in dealing with pregnancy, resulting in lower rates of low birth weight.