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- A'Roch, Roman, et al.
(författare)
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Left ventricular strain and peak systolic velocity : responses to controlled changes in load and contractility, explored in a porcine model
- 2012
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Ingår i: Cardiovascular Ultrasound. - : BioMed Central. - 1476-7120. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Tissue velocity echocardiography is increasingly used to evaluate global and regional cardiac function. Previous studies have suggested that the quantitative measurements obtained during ejection are reliable indices of contractility, though their load-sensitivity has been studied in different settings, but still remains a matter of controversy. We sought to characterize the effects of acute load change (both preload and afterload) and change in inotropic state on peak systolic velocity and strain as a measure of LV contractility.METHODS: Thirteen anesthetized juvenile pigs were studied, using direct measurement of left ventricular pressure and volume and transthoracic echocardiography. Transient inflation of a vena cava balloon catheter produced controlled load alterations. At least eight consecutive beats in the sequence were analyzed with tissue velocity echocardiography during the load alteration and analyzed for change in peak systolic velocities and strain during same contractile status with a controlled load alteration. Two pharmacological inotropic interventions were also included to generate several myocardial contractile conditions in each animal.RESULTS: Peak systolic velocities reflected the drug-induced changes in contractility in both radial and longitudinal axis. During the acute load change, the peak systolic velocities remain stable when derived from signal in the longitudinal axis and from the radial axis. The peak systolic velocity parameter demonstrated no strong relation to either load or inotropic intervention, that is, it remained unchanged when load was systematically and progressively varied (peak systolic velocity, longitudinal axis, control group beat 1- 5.72 +/- 1.36 with beat 8- 6.49 +/- 1.28 cm/sec, 95% confidence interval), with the single exception of the negative inotropic intervention group where peak systolic velocity decreased a small amount during load reduction (beat 1- 3.98 +/- 0.92 with beat 8- 2.72 +/- 0.89 cm/sec). Systolic strain, however, showed a clear degree of load-dependence.CONCLUSIONS: Peak systolic velocity appears to be load-independent as tested by beat-to-beat load reduction, while peak systolic strain appears to be load-dependent in this model. Peak systolic velocity, in a controlled experimental model where successive beats during load alteration are assessed, has a strong relation to contractility. Peak systolic velocity, but not peak strain rate, is largely independent of load, in this model. More study is needed to confirm this finding in the clinical setting.
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| 2. |
- A'Roch, Roman, et al.
(författare)
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Left ventricular twist is load-dependent as shown in a large animal model with controlled cardiac load
- 2012
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Ingår i: Cardiovascular Ultrasound. - : BioMed Central. - 1476-7120. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Left ventricular rotation and twist can be assessed noninvasively by speckle tracking echocardiography. We sought to characterize the effects of acute load change and change in inotropic state on rotation parameters as a measure of left ventricular (LV) contractility.METHODS: Seven anesthetised juvenile pigs were studied, using direct measurement of left ventricular pressure and volume and simultaneous transthoracic echocardiography. Transient inflation of an inferior vena cava balloon (IVCB) catheter produced controlled load reduction. First and last beats in the sequence of eight were analysed with speckle tracking (STE) during the load alteration and analysed for change in rotation/twist during controlled load alteration at same contractile status. Two pharmacological inotropic interventions were also included to examine the same hypothesis in additionally conditions of increased and decreased myocardial contractility in each animal. Paired comparisons were made for different load states using the Wilcoxon's Signed Rank test.RESULTS: The inferior vena cava balloon occlusion (IVCBO) load change compared for first to last beat resulted in LV twist increase (11.67degrees +/-2.65degrees vs. 16.17degrees +/-3.56degrees respectively, p < 0.004) during the load alteration and under adrenaline stimulation LV twist increase 12.56degrees +/-5.1degrees vs. 16.57degrees +/-4.6degrees (p < 0.013), and though increased, didn't reach significance in negative inotropic condition. Untwisting rate increased significantly at baseline from 41.7degrees/s +/-41.6degrees/s vs.122.6degrees/s +/-55.8degrees/s (P < 0.039) and under adrenaline stimulation untwisting rate increased (55.3degrees/s +/-3.8degrees/s vs.111.4degrees/s +/-24.0degrees/s (p < 0.05), but did not systematically changed in negative inotropic condition.CONCLUSIONS: Peak systolic LV twist and peak early diastolic untwisting rate are load dependent. Differences in LV load should be included in the interpretation when serial measures of twist are compared.
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| 3. |
- Ricard, Jean-Damien, et al.
(författare)
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A European survey of nosocomial infection control and hospital-acquired pneumonia prevention practices
- 2012
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Ingår i: Journal of Infection. - : Elsevier BV. - 0163-4453 .- 1532-2742. ; 65:4, s. 285-291
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: We aimed to examine organizational, structural and routine infection control measures provided by European ICUs and staff practices in ventilator-associated pneumonia prevention in relation with current recommendations.Methods: European ICU staffs were invited to complete a web-based 20 closed-item questionnaire.Results: 675 nurses and 886 physicians from 13 countries answered the questionnaire. Median number of respondents per country was 118.0 (64.5-155.5). Availability and organizational aspects of infection control revealed wide variations between countries. Among them, single-patient rooms was the aspect with the lowest availability (median availability 38%), but the largest variation ranging from 15 to 84%. Self-reported median adherence rate to recommendations was 72% (34.5-83.0) with a strong correlation between nurses and physicians responses (r(2) = 0.96; p < 0.0001). Sub-glottic drainage (31%), and infrequent ventilatory-circuit change (24%) were the measures with the lowest adherence rate whereas preferential use of oral intubation (90%) and of NIV (84%) and use of HMEs (82%) were the three with the highest rate. Organization of infection control was consistently self-reported. Disparities among countries were more frequent for specific actions regarding airway management, and even moreso for controversial issues (subglottic drainage, closed-suction systems).Conclusion: This European survey shows a 72% overall adherence rate to VAP prevention measures; with strong agreements between physician and nurses but considerable differences among countries for availability and organization aspects of infection control, providing healthcare authorities with figures for future programs.
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