Biomechanical analysis of practitioner's gesture for peripheral venous catheter insertion

Peripheral venous catheter insertion (PVCI) is one of the most common procedures performed by healthcare professionals but remains technically difficult. To develop new medical simulators with better representativeness of the human forearm, an experimental study was performed to collect data related to the puncturing of human skin and a vein in the antebrachial area. A total of 31 volunteers participated in this study. Force sensors and digital image correlation were used to measure the force during the palpation and puncturing of the vein and to retrieve the kinematics of the practitioner's gesture. The in vivo skin rupture load, vein rupture load, and friction loads for skin only and for both the skin and vein were (mean ± standard deviation) 0.85 ± 0.34 N, 1.25 ± 0.37 N, -0.49 ± 0.19 N, and -0.51 ± 0.16 N, respectively. The results of this study can be used to develop realistic skin and vein substitutes and mechanically assess them by reproducing the practitioner's gesture in a controlled fashion.

Ultrafast laser spatial beam shaping based on Zernike polynomials for surface processing

In femtosecond laser machining, spatial beam shaping can be achieved with wavefront modulators. The wavefront modulator displays a pre-calculated phase mask that modulates the laser wavefront to generate a target intensity distribution in the processing plane. Due to the non-perfect optical response of wavefront modulators, the experimental distribution may significantly differ from the target, especially for continuous shapes. We propose an alternative phase mask calculation method that can be adapted to the phase modulator optical performance. From an adjustable number of Zernike polynomials according to this performance, a least square fitting algorithm numerically determines their coefficients to obtain the desired wavefront modulation. We illustrate the technique with an optically addressed liquid-crystal light valve to produce continuous intensity distributions matching a desired ablation profile, without the need of a wavefront sensor. The projection of the experimental laser distribution shows a 5% RMS error compared to the calculated one. Ablation of steel is achieved following user-defined micro-dimples and micro-grooves targets on mold surfaces. The profiles of the microgrooves and the injected polycarbonate closely match the target (RMS below 4%).

Femtosecond laser ablation of polypropylene: A statistical approach of morphological data

We have investigated femtosecond (fs) laser (130 fs, 800 nm, 5 kHz) ablation of polypropylene (PP). The following laser process conditions were varied: power density and number of pulses. The morphological parameters' response (depth, ablation diameter, ablation volume) to the laser process conditions, measured by an optical profiler, was investigated by the statistical analysis technique to determine the relationship between them. For this, the simple linear regression and the multiple linear regressions are compared. The simple linear regression shows that the ablation volume follows a linear relationship with the product of the power and the number of pulse.

Chronic inflammation is negatively associated with prostate cancer and high-grade prostatic intraepithelial neoplasia on needle biopsy

Tissue inflammation has been linked to cancer in several disease models. We tested the association between chronic inflammation and prostate cancer (PCa), as well as high-grade prostatic intraepithelial neoplasia (HGPIN), in prostatic needle biopsy specimens. Tissues from 4526 men, who underwent systematic ultrasound-guided sextant needle biopsies of the prostate, were classified in the following order as PCa, or HGPIN, or chronic inflammation or benign. PCa was diagnosed in 1633 (36.1%), HGPIN in 535 (11.8%) and chronic inflammation in 347 (7.7%). Chronic inflammation conferred a protective effect from PCa: odds ratio (OR) = 0.20, 95% confidence interval (CI) = 0.15-0.28. Chronic inflammation was also inversely associated with HGPIN: OR = 0.11, 95% CI = 0.05-0.22. The ORs remained virtually unchanged after adjustment for age, serum prostate-specific antigen (PSA), digital rectal examination (DRE) and gland volume. Chronic inflammation is more frequent in the presence of benign histology than it is in the presence of PCa or HGPIN.

Myocardial tracking, a new method to calculate ejection fraction with gated SPECT: validation with (201)Tl versus planar angiography

Left ventricular ejection fraction (LVEF) and viability are essential variables for the prognosis of myocardial infarction and can be measured simultaneously by (201)Tl gated SPECT; however, most algorithms tend to underestimate LVEF. This study aimed to evaluate a new myocardial tracking algorithm, MyoTrack (MTK), for automatic LVEF calculation.

METHODS

A rest/redistribution (20 min/4 h) (201)Tl gated SPECT protocol followed immediately by a (99m)Tc equilibrium radionuclide angiography (ERNA) was performed in 75 patients with history of myocardial infarction. Quality of myocardial uptake was evaluated from count statistics and automatic quantification of defect sizes and severities (CardioMatch). LVEFs were calculated both with Germano's quantitative gated SPECT (QGS) algorithm and with MTK. Briefly, the originality of this algorithm resides in the unique end-diastole segmentation, matching to a template and motion field tracking throughout the cardiac cycle.

RESULTS

ERNA LVEF averaged 33% +/- 14%. QGS significantly underestimated this value at 20 min (30% +/- 13%, P < 0.001) and at 4 h (30% +/- 13%, P < 0.0001). By contrast, MTK did not miscalculate LVEF at 20 min (34% +/- 14%, probability value was not significant) though a similar underestimation occurred at 4 h (31% +/- 13%, P < 0.02). Individual differences between early and late gated SPECT values and differences between gated SPECT and ERNA values did not correlate with the extension of perfusion defects, count statistics, or heart rate.

CONCLUSION

MTK algorithm accurately calculates LVEF on early/high-count images compared with ERNA [corrected], even in patients with severe perfusion defects, but tends to underestimate LVEF on delayed/low-contrast images, as other algorithms do.

The impact of combined inhaled bronchodilator therapy in the treatment of COPD

BACKGROUND

Treatment guidelines recommend concomitant use of ipratropium bromide and inhaled beta2-agonists as severity of COPD progresses. While the use of these two agents in a single inhaler may enhance patient compliance and result in cost savings, it may, by itself, increase medication use. We assessed whether the introduction of a combined inhaled bronchodilator in the treatment of COPD modifies the use and costs related to prescribed medications.

METHOD

A cohort of subjects > or =45 years old initiating treatment with either a combined inhaled bronchodilator (641 subjects) or ipratropium bromide and inhaled beta2 -agonist (411 subjects) between July 1, 1996, and June 30, 1997, was identified using the Saskatchewan Health databases. The primary outcomes were prescribed medication usage and the subsequent related costs during a 1-year follow-up period. Poisson regression analysis was used to estimate rate ratios (RRs) adjusted for drug use and hospitalization during the year prior to cohort entry.

RESULTS

The adjusted RR of inhaled bronchodilator use was elevated for combined inhaled bronchodilator therapy (adjusted RR, 1.16; 95% confidence interval [CI], 1.07 to 1.26). However, the overall costs associated with these inhaled bronchodilators were reduced with combined inhaled bronchodilator therapy (adjusted mean ratio, 0.83; 95% CI, 0.76 to 0.92). The rate of use of other respiratory drugs and antibiotics was similar (adjusted RR, 1.03; 95% CI, 0.93 to 1.16). Applying the rate ratio for cost savings to all new, combined inhaled bronchodilator users led to estimated annual savings in Canadian dollars of 103,468 dollars (95% CI, 48,694 dollars to 146,082 dollars) in this province.

CONCLUSION

The introduction of a simpler bronchodilator dosing regimen did not significantly alter the treatment of COPD and resulted in appreciable cost savings.

Low-dose inhaled corticosteroids and the prevention of death from asthma

BACKGROUND

Although inhaled corticosteroids are effective for the treatment of asthma, it is uncertain whether their use can prevent death from asthma.

METHODS

We used the Saskatchewan Health data bases to form a population-based cohort of all subjects from 5 through 44 years of age who were using antiasthma drugs during the period from 1975 through 1991. We followed subjects until the end of 1997, their 55th birthday, death, emigration, or termination of health insurance coverage; whichever came first. We conducted a nested case-control study in which subjects who died of asthma were matched with controls within the cohort according to the length of follow-up at the time of death of the case patient (the index date), the date of study entry, and the severity of asthma. We calculated rate ratios after adjustment for the subject's age and sex; the number of prescriptions of theophylline, nebulized and oral beta-adrenergic agonists, and oral corticosteroids in the year before the index date; the number of canisters of inhaled beta-adrenergic agonists used in the year before the index date; and the number of hospitalizations for asthma in the two years before the index date.

RESULTS

The cohort consisted of 30,569 subjects. Of the 562 deaths, 77 were classified as due to asthma. We matched the 66 subjects who died of asthma for whom there were complete data with 2681 controls. Fifty-three percent of the case patients and 46 percent of the control patients had used inhaled corticosteroids in the previous year, most commonly low-dose beclomethasone. The mean number of canisters was 1.18 for the patients who died and 1.57 for the controls. On the basis of a continuous dose-response analysis, we calculated that the rate of death from asthma decreased by 21 percent with each additional canister of inhaled corticosteroids used in the previous year (adjusted rate ratio, 0.79; 95 percent confidence interval, 0.65 to 0.97). The rate of death from asthma during the first three months after discontinuation of inhaled corticosteroids was higher than the rate among patients who continued to use the drugs.

CONCLUSIONS

The regular use of low-dose inhaled corticosteroids is associated with a decreased risk of death from asthma.

Computed tomographic diagnosis of bronchogenic carcinoma in HIV-infected patients

PURPOSE

To describe the features of bronchogenic carcinoma (BC) on plain radiography and computed tomography (CT) in human immunodeficiency virus (HIV)-infected patients; to evaluate percutaneous transthoracic needle biopsy (PTNB) in this setting; and to assess outcome.

PATIENTS AND METHODS

We reviewed the medical charts, radiographs and chest CT scans in 15 AIDS patients with histologically proven BC. All but one of the patients were young men (mean age 48 years) with a long history of smoking (mean 40 pack-years). Adenocarcinoma was the predominant cell type (46.6%). The stage of the malignancy did not correlate with the CD4 cell count (mean 189 per mm(3)). The diagnosis was obtained by means of PTNB (n=7), bronchoscopy (n=4), thoracotomy (n=2), pleural biopsy (n=1) or extrathoracic biopsy (n=1).

RESULTS

Parenchymal masses and nodules were the most common features (66.6%) on chest radiographs and CT. BC was peripheral in 11 cases (73%) and was located in the upper lobe in ten cases (66.6%). Enlarged lymph nodes were present in 60% of patients and metastases in 30%. PTNB was diagnostic in seven of the eight patients who underwent the procedure; complications included two pneumothoraces and one secondary implantation of tumor cells along the needle tract. Three lobectomies and one pneumonectomy were performed for stage I disease. The mean survival time among the patients who underwent surgery was 14 months. These survivals are more encouraging than some of those previously reported in the literature, furthermore, patients die of competing illnesses.

CONCLUSION

BC in HIV-infected patients is similar to that in the general population. Early diagnosis can be achieved by means of PTNB. Surgical resection, when feasible, significantly improves survival.

Primary pulmonary AIDS-related lymphoma: radiographic and CT findings

STUDY OBJECTIVES

To describe the radiographic and CT findings of primary AIDS-related lymphoma (ARL) of the lung (ARLL), and to evaluate percutaneous transthoracic needle biopsy (PTNB) in the diagnosis of primary ARLL.

MATERIALS AND METHODS

Seven chest radiographs and seven CT scans of HIV-infected patients with histologically proved primary pulmonary non-Hodgkin's lymphoma (PPL) were reviewed at our institution. All of the patients had fibroscopy with BAL. The diagnosis of PPL was established histologically by means of PTNB (n = 4), open-lung biopsy (n = 2), or autopsy (n = 1).

RESULTS

All but one patient had multiple peripheral well-defined nodules of various sizes on the chest X-ray film and CT scan. One patient had a subpleural parenchymal infiltrate and another had a main peripheral mass with spontaneous cavitation. Hilar/mediastinal adenopathies and pericardial/pleural effusion were never associated with the parenchymal abnormalities. Fibroscopy with BAL was always negative. PTNB, done in six cases, was diagnostic in four cases and suggested primary ARLL in two cases. No complications occurred during these procedures.

CONCLUSION

After excluding infectious causes, multiple peripheral nodules and/or masses without hilar or mediastinal adenopathies and without pleural effusion are suggestive of primary pulmonary ARL. A specific diagnosis can be obtained by means of PTNB.