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Biomedical subjects

S Laporte

Publications and source records attributed to S Laporte.

At least 19 recordsLinked to original sources
PubMed2006

A randomized study comparing the efficacy and safety of nadroparin 2850 IU (0.3 mL) vs. enoxaparin 4000 IU (40 mg) in the prevention of venous thromboembolism after colorectal surgery for cancer.

BACKGROUND: The optimal thromboprophylactic dosage regimen of low-molecular-weight heparins in high-risk general surgery remains debatable. OBJECTIVES: We performed a randomized, double-blind study to compare the efficacy and safety of nadroparin 2850 IU (0.3 mL) and enoxaparin 4000 IU (40 mg) in the prevention of venous thromboembolism (VTE) after colorectal surgery for cancer. PATIENTS AND METHODS: Patients undergoing resection of colorectal adenocarcinoma were randomized to receive once daily either 2850 IU nadroparin or 4000 IU enoxaparin s.c. for 9 +/- 2 days. The primary efficacy outcome was the composite of deep vein thrombosis (DVT) detected by bilateral venography or documented symptomatic DVT or pulmonary embolism up to day 12. The main safety outcome was major bleeding. A blinded independent committee adjudicated all outcomes. RESULTS: Out of 1288 patients analyzed, efficacy was evaluable in 950 (73.8%) patients. The VTE rate was 15.9% (74/464) in nadroparin-treated patients and 12.6% (61/486) in enoxaparin-treated patients, a relative risk of 1.27 (95% confidence interval; CI: 0.93-1.74) that did not met the criterion for non-inferiority of nadroparin. The rate of proximal DVT was comparable in the two groups (3.2% vs. 2.9%, respectively), but that of symptomatic VTE was lower in nadroparin-treated patients (0.2% vs. 1.4%). There was significantly (P = 0.012) less major bleeding in nadroparin- than in enoxaparin-treated patients (7.3% vs. 11.5%, respectively). CONCLUSION: Compared with those receiving enoxaparin 4000 IU, patients treated with nadroparin 2850 IU showed a higher incidence of asymptomatic distal DVT, but a lower incidence of symptomatic VTE. Nadroparin treatment was safer in terms of bleeding risk.

Adult↗
PubMed2006

3D reconstruction of the pelvis from bi-planar radiography.

3D personalized models are more and more requested for clinical and biomechanical studies. Techniques based on bi-planar X-rays present the advantage of a low radiation dose for the patient. However, up to now, such techniques have shown limited accuracy in the case of pelvis reconstruction. This study proposes and validates a method providing accurate 3D personalized model of the pelvis from bi-planar X-rays. The algorithm is based on the fast computation of an initial solution followed by local deformations based on 2D anatomical points and contours that are digitized in both radiographs. Results were close to CT-scan reconstructions (mean difference 1.6 mm and differences under 4.3 mm for 95% of the points). Moreover, 3D morphometry of the pelvis could be obtained with an accuracy of 5%. This technique provides 3D patient specific model with a low radiation dose.

Aged↗
PubMed2005

[Is very old age a prognostic factor for outcome after a first stroke?].

AIM: To determine whether very old age, older than 80 years, after a stroke is a significant predictor of mortality, orientation to a specific care pathway after the acute phase and functional status at 6 months after the stroke. PATIENTS: A sample of 112 consecutive patients admitted to the emergency department because of a first stroke, with hemiplegia and/or aphasia over 6 months, who satisfied strict inclusion/exclusion criteria. Forty-seven patients were older than 80. METHOD: After initial diagnosis and enrolment in the study, follow-up assessments were conducted at 48 hours, 15 days and 6 months. Demographic, medical, and radiographic data were collected, and patients were evaluated on the NIHSS, MMSE, Barthel Index, FIM(TM) and FAM scales. Descriptive statistics were generated, as were uni- and multivariate between group comparisons. RESULTS: Our study shows that after a first stroke, old age is significantly associated with a high rate of death, a low rate of orientation to a physical medicine and rehabilitation unit and return to home but not poorer functional outcome. CONCLUSION: Old age is therefore a determinant of post stroke management. Further studies are needed to evaluate whether in patient rehabilitation would result in significant functional benefit, considering the high cost of care, high risk of recurrent stroke, and high rate of death.

Age Factors↗
PubMed2005

[Digestive surgery and varicose vein surgery].

The thromboembolic risk related to surgery may be considered as low for varicose vein surgery and non major digestive surgery. It could be defined as moderate in case of large dissection, long duration of procedures and emergency cases. The risk may be considered as high for major abdominal surgery involving cancer surgery or not and bariatric surgery. The absence of prophylaxis can be proposed for low risk surgery (grade B). However, elastic compression stocking are effective for all cases of digestive surgery and suggested to be used (grade A). There are no data concerning the moderate risk situation. Therefore, experts recommend the use of elastic compression stockings or low doses of LMWH (grade D). High-risk surgery requires the use of high doses of LMWH recommended for reasons of efficacy, tolerance, and easiness to use (grade A). Associated elastic stockings is efficious (grade B). The duration of prophylaxis lasts generally 7-10 days. Extension to 1 month is recommended for major abdominal cancer surgery (grade A).

Ambulatory Surgical Procedures↗
PubMed2004

Rotations of three-joint fingers: a radiological study.

The aim of the current study was to test a protocol of quantification of phalangeal three-dimensional (3D) rotations during flexion of three-joint digits. Three-dimensional-specific software was developed to analyze CT reconstruction images. A protocol was carried out with six fresh-frozen upper limbs from human cadavers free from any visible pathology (three females, three males). CT millimetric slices were done for reconstruction of hand bone units. Orthonormal coordinate systems of inertia were calculated for each unit. Three-dimensional phalangeal rotations were estimated between two static positions (fingers in extension and in a fist position). Results were displayed for the joints of each three-joint finger with calculation of 3D rotations. Mean longitudinal axial rotations of metacarpophalangeal (MCP), proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints ranged from 14 degrees pronation to 19 degrees supination. The index finger was in a global pronation position (4/6 specimens). The fourth and fifth fingers were in a global supination position in every case. The third finger was in a more variable global rotation (pronation in 2/6 specimens). MCP, PIP and DIP flexion angles ranged respectively from 71 degrees to 89 degrees, 65 degrees to 87 degrees, and 41degrees to 77 degrees. Lateral angles ranged from 19 degrees (ulnar angulation) to 23 degrees (radial angulation). The study of phalangeal rotations was possible in spite of a heavy protocol. This protocol could be partially automatated to speed up the analyses. Longitudinal axial rotations could be analyzed, in addition to flexion/extension or abduction/adduction rotations. CT scan reconstructions would be helpful for investigating pathological fingers. Abnormal rotations of digits could be quantified more precisely than during a current clinical examination of the hand.

Aged↗
PubMed2004

Prevention of venous thromboembolism in orthopedic surgery with vitamin K antagonists: a meta-analysis.

BACKGROUND: The benefit-to-risk ratio of vitamin K antagonists (VKA), relative to active comparators, especially low-molecular-weight heparins (LMWH), for preventing venous thromboembolism in patients undergoing major orthopedic surgery is debated. OBJECTIVES: We performed a meta-analysis of all randomized trials in orthopedic surgery comparing adjusted doses of VKA to control treatments. PATIENTS AND METHODS: An exhaustive literature search, both manual and computer-assisted, was performed. Studies were selected on the basis of randomization procedure (VKA vs. a control group). At least one of the following outcome measures was to be evaluated: deep vein thrombosis (DVT), pulmonary embolism (PE), death, major hemorrhage or wound hematoma. Four reviewers assessed each article to determine eligibility for inclusion and outcome measures. RESULTS: VKAs were more effective than placebo or no treatment in reducing DVT [567 patients, relative risk (RR) = 0.56, 95% confidence interval (CI) 0.37, 0.84, P < 0.01] and clinical PE (651 patients, RR = 0.23, 95% CI 0.09, 0.59, P < 0.01). These results were obtained at the cost of a higher rate of wound hematoma (162 patients, RR = 2.91, 95% CI 1.09, 7.75, P = 0.03). VKAs were also more effective than intermittent pneumatic compression (534 patients, RR = 0.46, 95% CI 0.25, 0.82, P = 0.009) in preventing proximal DVT. In contrast, VKAs were less effective than LMWH in preventing total DVT and proximal DVT (9822 patients, RR = 1.51, 95% CI 1.27, 1.79, P < 0.001; and 6131 patients, RR = 1.51, 95% CI 1.04, 2.17, P = 0.028, respectively). The differences between VKA and LMWH in major hemorrhage and wound hematoma were not significant. CONCLUSIONS: In patients undergoing major orthopedic surgery, VKAs are less effective than LMWH, without any significant difference in the bleeding risk.

Fibrinolytic Agents↗
PubMed2004

3D reconstruction of the proximal femur with low-dose digital stereoradiography.

OBJECTIVE: Accurate three-dimensional (3D) geometry of the proximal femur may be helpful for fracture risk evaluation, as well as for planning and assisting surgical procedures. The purpose of this study was to apply and validate a stereoradiographic 3D reconstruction method on the proximal femur from radiographic contours identified on bi-planar radiographs. MATERIALS AND METHODS: Twenty-five excised non-pathologic proximal femurs were investigated using a low-dose digital radiographic device. Three-dimensional personalized models were reconstructed using the Non-Stereo Corresponding Contours (NSCC) algorithm. Three-dimensional CT-scan reconstructions were defined as geometric references for the comparison protocol, in order to assess the accuracy and reproducibility of the personalized 3D stereoradiographic reconstructions. In addition, the reliability of a set of 3D parameters obtained from stereoradiographic models was evaluated. RESULTS: This study demonstrated the validity of the NSCC method when applied to the proximal femur, with good results for accuracy (mean error = 0.7 mm) and reproducibility (Wilcoxon test: p > 0.28). Moreover, a precision study for the set of 3D parameters yielded a coefficient of variation lower than 5%. CONCLUSIONS: Once this approach has been validated in vivo, it should find multiple applications in therapeutic fields (e.g., for surgical planning, computer assisted surgery, etc.), as well as in diagnostic contexts (e.g., equilibrium studies or osteoporosis fracture risk assessment).

Aged↗
PubMed2003

Explicit calibration method and specific device designed for stereoradiography.

The three-dimensional geometry of the human spine is noteworthy information that can be obtained by stereoradiographic methods. These methods are based on the identification of anatomical structures in several views which are obtained by rotation of a patient standing on a turntable. Calibration algorithms for computer vision or photogrammetry are well documented, but they generally yield calibration devices which are cumbersome for the use in clinical stereoradiography. This paper presents a calibration method adapted to a two-view stereoradiography calibration (frontal and lateral incidences) and based on a simplified geometric modeling of the radiological environment. The a priori knowledge yields four calibration equations related to the vertical and horizontal planes of both views, leading to a specific calibration procedure and device. Moreover this device is attached to the stereoradiographic system (directly integrated on the turntable) in order to facilitate clinical applications. A validation was performed on 26 dried lumbar vertebrae in order to evaluate clinical situation. The mean accuracy of the stereoradiographic reconstruction was 1.2mm.

Aged↗
PubMed2003

Poor anticoagulant response to tissue factor pathway inhibitor in patients with venous thrombosis.

Tissue factor pathway inhibitor (TFPI) is of major importance in regulating the coagulation triggering effects of tissue factor. An association between TFPI deficiency and thrombosis has still not been clearly demonstrated. We evaluated the anticoagulant activity of exogenous TFPI added either to the plasma of patients with venous thrombosis (n = 118) or to the plasma of healthy controls similar in terms of mean age and sex ratio (n = 107). A poor anticoagulant response to TFPI, defined as TFPI resistance, was observed in 4.7% of controls and in 11.0% of patients. TFPI resistance was associated with an almost threefold increase in the risk of thrombosis and could therefore represent a novel hemostatic risk factor for venous thrombosis.

Adult↗
PubMed2003

A biplanar reconstruction method based on 2D and 3D contours: application to the distal femur.

A three-dimensional (3D) reconstruction algorithm based on contours identification from biplanar radiographs is presented. It requires, as technical prerequisites, a method to calibrate the biplanar radiographic environment and a surface generic object (anatomic atlas model) representing the structure to be reconstructed. The reconstruction steps consist of: the definition of anatomical regions, the identification of 2D contours associated to these regions, the calculation of 3D contours and projection onto the radiographs, the associations between points of the X-rays contours and points of the projected 3D contours, the optimization of the initial solution and the optimized object deformation to minimize the distance between X-rays contours and projected 3D contours. The evaluation was performed on 8 distal femurs comparing the 3D models obtained to CT-scan reconstructions. Mean error for each distal femur was 1 mm.

Algorithms↗
PubMed2002

[Laparoscopic re-establishment of digestive continuity following Hartmann's procedure. Retrospective study of the French Society of Endoscopic Surgery].

STUDY AIM: Reversal of the Hartmann's procedure is associated with a high morbidity. The aim of this study was to evaluate the feasibility and results of laparoscopic reversal of the Hartmann's procedure. PATIENTS AND METHOD: Thirty eight consecutive patients, mean age 60 +/- 13.5 years were included in this retrospective study. The most common indication for the primary procedure was diverticular disease (70%). The mean time from the primary operation to the reconstruction was 136 +/- 124 days. The stoma was first dissected in 24 patients, allowing introduction of the first port. In the remaining 14 patients a standard umbilical port was inserted. The amount of adhesions was classified as low in 13 patients, mild in 15 patients and severe in 10 patients. All patients had a mechanical anastomosis. RESULTS: The conversion rate was 15%, due to adhesion problems in 5 patients and for a positive leakage test in one. The morbidity rate was 23.5% including 8 surgical complications. One patient died after post operative peritonitis complicating an anastomic leakage. The average hospital stay was 10 +/- 4.4 days. CONCLUSION: Our results indicate that laparoscopic reversal after Hartmann's procedure is feasible. The morbidity is lower than after classical open reconstruction. The presence of diffuse peritonitis at the primary operation as well as a short delay before the reconstruction, are important factors of conversion.

Aged↗
PubMed2002

Perioperative pharmacokinetics of factor VII concentrate during liver surgery in a patient with congenital factor VII deficiency: an individual mathematical model.

A patient with congenital factor VII deficiency (baseline activity, 7%) underwent surgery for hepatocellular carcinoma. No literature reference was found concerning the management of this coagulation defect in patients requiring liver surgery. We report one such case, with special reference to the peri-operative management of factor VII replacement therapy and the pharmacokinetic behavior of factor VII. As a result of accidental suprahepatic vein lesion, a bleeding episode occurred. This was associated with an increase in factor VII clearance and volume of distribution values from 1.30 to 3.85 l/h, and from 6.51 to 13.2 l, respectively. After surgery, the patient continued to receive the concentrate every 8 h during the first nine post-operative days. No post-operative bleeding or thrombotic event was observed. The patient was discharged in good condition.

Aged↗
PubMed2002

[What is the best timing to perform laparoscopic cholecystectomy in acute cholecystitis?].

Early laparascopic cholecystectomy within five days of onset of symptoms of acute cholecystitis has proved superior to open cholecystectomy. Feasability is well established; the conversion rate to open cholecystectomy and the post-operative morbidity are no higher than with delayed laparascopy after initial medical management. Total hospitalization is, on the other hand, significantly shorter. Only one study showed an increase in operative time with early surgery (on average 15 minutes). Both preoperative and perioperative risk factors for conversion to laparotomy were identified. Prompt laparascopic intervention avoids the complications which may arise with initial medical management, i.e., failure of medical management or biliary peritonitis. Early laparascopic cholecystectomy should be considered the gold standard for management of acute cholecystitis.

Acute Disease↗
PubMed2002

Simplified calibration system for stereoradiography in scoliosis.

Stereoradiography is a well known method to obtain 3D images of the spine and the thorax. The main algorithm used is the DLT, which is a very general one yielding to 11 implicit parameters per view. In order to calibrate the geometrical configuration of the stereoradiographic setup with this algorithm, there is a need of a wide calibrating object, leading to systems hard to use in clinical practice. The aim of this work was to modify the algorithm in order to simplify the calibration object. We used assumptions related to the specific case of stereoradiography, which reduced the problem of calibration to only 6 independent explicit parameters. A geometrical calibration performed plane by plane enabled to design a singular calibration object composed of steel balls along two vertical lines and three horizontal ones. A simulation of real configuration both for the previous method and the current algorithm associated to the singular calibrating object give for thirty 3D points a 2 RMS (95% confidence interval) error of reconstruction of respectively 0.6 and 0.3 mm. This study yielded to the transfer in clinics of two simplified systems of calibration which will be easier to use in clinical practice.

Calibration↗
PubMed2002

3D reconstruction of the pelvis using the NSCP technique.

Many authors have already pointed out the importance of the three dimensional aspect when dealing with pelvic and spinal pathologies. The purpose of the present study is to verify the feasibility on the pelvis and the accuracy of a recent 3D reconstruction technique based on biplanar X Rays with regard to direct measurements. The results on 8 dry non-pathologic pelvises show a mean error of 3.9 mm for the global geometry of the pelvis, with local maxima of 26 mm and 95% of errors inferior to 14.5 mm.

Aged↗
PubMed2002

3D detailed reconstruction of vertebrae with low dose digital stereoradiography.

As scoliosis requires a global and local 3D examination of the spine in standing position, stereoradiography appears as one of the most adequate 3D imaging tool for it diagnosis. Our purpose was to increase the geometry definition of the stereoradiographic reconstruction to obtain morpho-realistic models and to validate them using 41 dry vertebrae. Our results propose 2000 points 3D personalised models without any loss of accuracy in comparison to previous studies.

Algorithms↗